U.S. patent application number 11/790074 was filed with the patent office on 2007-11-01 for diagnosis system for vane-type variable valve timing controller.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Toshifumi Hayami, Wataru Nagashima, Masaei Nozawa.
Application Number | 20070251477 11/790074 |
Document ID | / |
Family ID | 38647141 |
Filed Date | 2007-11-01 |
United States Patent
Application |
20070251477 |
Kind Code |
A1 |
Nozawa; Masaei ; et
al. |
November 1, 2007 |
Diagnosis system for vane-type variable valve timing controller
Abstract
One-way valves are provided in a hydraulic pressure supply
passage in an advance hydraulic chamber and a hydraulic pressure
supply passage in a retard hydraulic chamber respectively. A drain
oil passage bypassing each of the one-way valves is provided in the
hydraulic pressure supply passage in the each hydraulic chamber to
be in parallel therewith. A drain switching valve is provided in
the each drain oil passage. A drain switching control function for
switching the hydraulic pressure driving the each drain switching
valve is integral with a function of the hydraulic control valve
for controlling the hydraulic pressure supplied to the advance
hydraulic chamber and the retard hydraulic chamber. It is
determined whether the responsiveness of an advance/retard
operation is in a normal range based upon a changing rate of the
VTC displacement angle during advance/retard operating, thereby
determining presence/absence of abnormality in the advance/retard
operation.
Inventors: |
Nozawa; Masaei;
(Okazaki-city, JP) ; Hayami; Toshifumi;
(Kariya-city, JP) ; Nagashima; Wataru;
(Kariya-city, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
38647141 |
Appl. No.: |
11/790074 |
Filed: |
April 23, 2007 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 2001/34426
20130101; F01L 1/3442 20130101; F01L 2001/34436 20130101; F01L
1/022 20130101; F01L 2820/041 20130101; F01L 2800/00 20130101; F01L
2001/34469 20130101; F01L 2820/042 20130101 |
Class at
Publication: |
123/090.17 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 24, 2006 |
JP |
2006-119354 |
Apr 27, 2006 |
JP |
2006-122763 |
Apr 28, 2006 |
JP |
2006-124825 |
Claims
1. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a one-way valve
disposed in each of a hydraulic supply passage of the advance
hydraulic chamber and a hydraulic supply passage of the retard
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the each
hydraulic chamber; a drain oil passage disposed in parallel to the
hydraulic supply passage of the each hydraulic chamber for
bypassing the one-way valve; a drain switching valve disposed in
the each drain oil passage and driven by hydraulic pressure; and a
hydraulic switching valve for switching the hydraulic pressure
driving the each drain switching valve, wherein: during hold
operating of holding a displacement angle of the variable valve
timing controller (hereinafter, referred to as VTC displacement
angle) to a target displacement angle, both the drain switching
valves in a side of the advance hydraulic chamber and a side of the
retard hydraulic chamber are closed to effectively function both
the one-way valves in the side of the advance hydraulic chamber and
the side of the retard hydraulic chamber; the hydraulic switching
valve is controlled to prevent reverse flow of the operating oil
from the each hydraulic chamber and also a control current of a
hydraulic control valve controlling the hydraulic pressure in the
each hydraulic chamber is controlled to a predetermined holding
current; during advance/retard operating of displacing the VTC
displacement angle to the advance direction or the retard
direction, either one of the drain switching valves in the side of
the advance hydraulic chamber and the side of the retard hydraulic
chamber is opened in accordance with the displacement direction to
control the hydraulic switching valve so that either one of the
one-way valves does not operate; and the control current of the
hydraulic control valve is controlled to vary the hydraulic
pressure in the each hydraulic chamber, displacing the VTC
displacement angle toward the target displacement angle, further
comprising: abnormality diagnosis means adapted to determine
presence/absence of abnormality in the advance/retard operation
based upon a changing rate of the VTC displacement angle when a
predetermined abnormality diagnosis execution condition is met
during the advance/retard operating.
2. A diagnosis device for a vane-type variable valve timing
controller according to claim 1, wherein: at least one of
abnormality diagnosis execution conditions is a condition that an
engine rotational speed is in a low rotational region less than a
predetermined rotational speed.
3. A diagnosis device for a vane-type variable valve timing
controller according to claim 1, wherein: at least one of
abnormality diagnosis execution conditions is a condition that a
deviation between the VTC displacement angle and the target
displacement angle is more than a predetermined value.
4. A diagnosis device for a vane-type variable valve timing
controller according to claim 1, wherein: at least one of
abnormality diagnosis execution conditions is a condition that a
predetermined time elapses after the target displacement angle has
changed.
5. A diagnosis device for a vane-type variable valve timing
controller according to claim 1, wherein: the abnormality diagnosis
means determines presence/absence of the abnormality in the
advance/retard operation in consideration of continuing time of a
state where a changing rate of the VTC displacement angle is less
than a predetermined value.
6. A diagnosis device for a vane-type variable valve timing
controller according to claim 1, wherein: the abnormality diagnosis
means includes means for determining presence/absence of
abnormality regarding the hydraulic control value and the hydraulic
switching valve, wherein when the abnormality of the advance
operation is detected, if it is determined that the hydraulic
control valve and the hydraulic switching valve are normal, the
means determines occurrence of a closed abnormality state where at
least one of the drain switching valve in the side of the retard
hydraulic chamber and the one-way valve in the side of the advance
hydraulic chamber remains to be closed or an open abnormality state
where at least one of the drain switching valve in the side of the
advance hydraulic chamber and the one-way valve in the side of the
advance hydraulic chamber remains to be opened; and wherein when
the abnormality of the retard operation is detected, if it is
determined that the hydraulic control valve and the hydraulic
switching valve are normal, the means determines occurrence of a
closed abnormality state where at least one of the drain switching
valve in the side of the advance hydraulic chamber and the one-way
valve in the side of the retard hydraulic chamber remains to be
closed or an open abnormality state where at least one of the drain
switching valve in the side of the retard hydraulic chamber and the
one-way valve in the side of the retard hydraulic chamber remains
to be opened.
7. A diagnosis device for a vane-type variable valve timing
controller according to claim 1, wherein: the hydraulic switching
valve is integral with the hydraulic control valve.
8. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a first one-way
valve disposed in a hydraulic supply passage of the advance
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the
advance hydraulic chamber; a first drain control valve disposed in
a first drain oil passage bypassing the first one-way valve and
driven by hydraulic pressure; a second one-way valve disposed in a
hydraulic supply passage of the retard hydraulic chamber in at
least one of the vane accommodating chambers for preventing reverse
flow of operating oil from the retard hydraulic chamber; a second
drain control valve disposed in a second drain oil passage
bypassing the second one-way valve and driven by the hydraulic
pressure; a first hydraulic control valve for controlling the
hydraulic pressure supplied to the variable valve timing
controller; a second hydraulic control valve for controlling the
hydraulic pressure driving the first and second drain control
valves, wherein: during hold operating of holding a displacement
angle of the variable valve timing controller (hereinafter,
referred to as VTC displacement angle) to a target displacement
angle, both the drain control valves in a side of the advance
hydraulic chamber and a side of the retard hydraulic chamber are
closed to effectively function both the one-way valves in the side
of the advance hydraulic chamber and the side of the retard
hydraulic chamber; the second hydraulic control valve is controlled
to prevent reverse flow of the operating oil from the advance
hydraulic chamber and the retard hydraulic chamber and also a
control current of the first hydraulic control valve controlling
the hydraulic pressure supplied to the variable valve timing
controller is controlled to a predetermined holding current; during
advance/retard operating of displacing the VTC displacement angle
to the advance direction or the retard direction, either one of the
drain control valves in the side of the advance hydraulic chamber
and the side of the retard hydraulic chamber is opened in
accordance with the displacement direction to control the second
hydraulic control valve so that either one of the one-way valves
does not operate; and the control current of the first hydraulic
control valve is controlled to vary the hydraulic pressure supplied
to the variable valve timing controller, displacing the VTC
displacement angle toward the target displacement angle, further
comprising: abnormality diagnosis means adapted to determine
presence/absence of abnormality in the advance/retard operation
based upon a changing rate of the VTC displacement angle when a
predetermined abnormality diagnosis execution condition is met
during the advance/retard operating.
9. A diagnosis device for a vane-type variable valve timing
controller according to claim 8, wherein: at least one of
abnormality diagnosis execution conditions is a condition that an
engine rotational speed is in a low rotational region less than a
predetermined rotational speed.
10. A diagnosis device for a vane-type variable valve timing
controller according to claim 8, wherein: at least one of
abnormality diagnosis execution conditions is a condition that a
deviation between the VTC displacement angle and the target
displacement angle is more than a predetermined value.
11. A diagnosis device for a vane-type variable valve timing
controller according to claim 8, wherein: at least one of
abnormality diagnosis execution conditions is a condition that a
predetermined time elapses after the target displacement angle has
changed.
12. A diagnosis device for a vane-type variable valve timing
controller according to claim 8, wherein: the abnormality diagnosis
means determines presence/absence of the abnormality in the
advance/retard operation in consideration of continuing time of a
state where a changing rate of the VTC displacement angle is less
than a predetermined value.
13. A diagnosis device for a vane-type variable valve timing
controller according to claim 8, wherein: the abnormality diagnosis
means includes means for determining presence/absence of the
abnormality regarding the first hydraulic control value and the
second hydraulic control valve, wherein when the abnormality of the
advance operation is detected, if it is determined that the first
hydraulic control valve and the second hydraulic control valve are
normal, the means determines occurrence of a closed abnormality
state where at least one of the drain switching valve in the side
of the retard hydraulic chamber and the one-way valve in the side
of the advance hydraulic chamber remains to be closed or an open
abnormality state where at least one of the drain switching valve
in the side of the advance hydraulic chamber and the one-way valve
in the side of the advance hydraulic chamber remains to be opened;
and wherein when the abnormality of the retard operation is
detected, if it is determined that the first hydraulic control
valve and the second hydraulic control valve are normal, the means
determines occurrence of a closed abnormality state where at least
one of the drain control valve in the side of the advance hydraulic
chamber and the one-way valve in the side of the retard hydraulic
chamber remains to be closed or an open abnormality state where at
least one of the drain control valve in the side of the retard
hydraulic chamber and the one-way valve in the side of the retard
hydraulic chamber remains to be opened.
14. A diagnosis device for a vane-type variable valve timing
controller according to claim 8, wherein: a shaft for driving the
first hydraulic control valve is integral with a shaft for driving
the second hydraulic control valve.
15. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a first one-way
valve disposed in a hydraulic supply passage of the advance
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the
advance hydraulic chamber; a first drain control valve disposed in
a first drain oil passage bypassing the first one-way valve and
driven by hydraulic pressure; a second one-way valve disposed in a
hydraulic supply passage of the retard hydraulic chamber in at
least one of the vane accommodating chambers for preventing reverse
flow of operating oil from the retard hydraulic chamber; a second
drain control valve disposed in a second drain oil passage
bypassing the second one-way valve and driven by the hydraulic
pressure; a single first hydraulic control valve for controlling
the hydraulic pressure supplied to the first and second drain
control valves and the variable valve timing controller; wherein:
during hold operating of holding a displacement angle of the
variable valve timing controller (hereinafter, referred to as VTC
displacement angle) to a target displacement angle, a control
current of the hydraulic control valve is controlled to a
predetermined holding current to close both the drain control
valves in a side of the advance hydraulic chamber and a side of the
retard hydraulic chamber to effectively function both the one-way
valves in the side of the advance hydraulic chamber and the side of
the retard hydraulic chamber; thereby preventing reverse flow of
the operating oil from the advance hydraulic chamber and the retard
hydraulic chamber and also controlling the hydraulic pressure
supplied to the variable valve timing controller; during
advance/retard operating of displacing the VTC displacement angle
to the advance direction or the retard direction, the control
current of the hydraulic control valve is controlled to open either
one of the drain control valves in a side of the advance hydraulic
chamber and a side of the retard hydraulic chamber in accordance
with the displacement direction so that either one of the one-way
valves does not operate; and further, the hydraulic pressure
supplied to the variable valve timing controller is varied, thereby
displacing the VTC displacement angle toward the target
displacement angle, further comprising: abnormality diagnosis means
adapted to determine presence/absence of abnormality in the
advance/retard operation based upon a changing rate of the VTC
displacement angle when a predetermined abnormality diagnosis
execution condition is met during the advance/retard operating.
16. A diagnosis device for a vane-type variable valve timing
controller according to claim 15, wherein: at least one of
abnormality diagnosis execution conditions is a condition that an
engine rotational speed is in a low rotational region less than a
predetermined rotational speed.
17. A diagnosis device for a vane-type variable valve timing
controller according to claim 15, wherein: at least one of
abnormality diagnosis execution conditions is a condition that a
deviation between the VTC displacement angle and the target
displacement angle is more than a predetermined value.
18. A diagnosis device for a vane-type variable valve timing
controller according to claim 15, wherein: at least one of
abnormality diagnosis execution conditions is a condition that a
predetermined time elapses after the target displacement angle has
changed.
19. A diagnosis device for a vane-type variable valve timing
controller according to claim 15, wherein: the abnormality
diagnosis means determines presence/absence of the abnormality in
the advance/retard operation in consideration of continuing time of
a state where a changing rate of the VTC displacement angle is less
than a predetermined value.
20. A diagnosis device for a vane-type variable valve timing
controller according to claim 15, wherein: the abnormality
diagnosis means includes means for determining presence/absence of
the abnormality regarding the hydraulic control value, wherein when
the abnormality of the advance operation is detected, if it is
determined that the hydraulic control valve is normal, the means
determines occurrence of a closed abnormality state where at least
one of the drain control valve in the side of the retard hydraulic
chamber and the one-way valve in the side of the advance hydraulic
chamber remains to be closed or an open abnormality state where at
least one of the drain control valve in the side of the advance
hydraulic chamber and the one-way valve in the side of the advance
hydraulic chamber remains to be opened; and wherein when the
abnormality of the retard operation is detected, if it is
determined that the hydraulic control valve is normal, the means
determines occurrence of a closed abnormality state where at least
one of the drain control valve in the side of the advance hydraulic
chamber and the one-way valve in the side of the retard hydraulic
chamber remains to be closed or an open abnormality state where at
least one of the drain control valve in the side of the retard
hydraulic chamber and the one-way valve in the side of the retard
hydraulic chamber remains to be opened.
21. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a one-way valve
disposed in each of a hydraulic supply passage of the advance
hydraulic chamber and a hydraulic supply passage of the retard
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the each
hydraulic chamber; a drain oil passage disposed in parallel to the
hydraulic supply passage of the each hydraulic chamber for
bypassing the one-way valve; a drain switching valve disposed in
the each drain oil passage and driven by hydraulic pressure; and a
hydraulic switching valve for switching the hydraulic pressure
driving the each drain switching valve, wherein: during hold
operating of holding a displacement angle of the variable valve
timing controller (hereinafter, referred to as VTC displacement
angle) to a target displacement angle, both the drain switching
valves in a side of the advance hydraulic chamber and a side of the
retard hydraulic chamber are closed to effectively function both
the one-way valves in the side of the advance hydraulic chamber and
the side of the retard hydraulic chamber; thereby, the hydraulic
switching valve is controlled to prevent reverse flow of the
operating oil from both the hydraulic chambers and also a control
current of the hydraulic control valve controlling the hydraulic
pressure in the each hydraulic chamber is controlled to a
predetermined holding current; during advance/retard operating of
displacing the VTC displacement angle to the advance direction or
the retard direction, either one of the drain switching valves in a
side of the advance hydraulic chamber and a side of the retard
hydraulic chamber is opened in accordance with the displacement
direction to control the hydraulic switching valve so that either
one of the one-way valves does not operate; and the control current
of the hydraulic control valve is controlled to vary the hydraulic
pressure in the each hydraulic chamber, displacing the VTC
displacement angle toward the target displacement angle, further
comprising: when at the time of meeting a predetermined abnormality
diagnosis execution condition during the advance/retard operating,
the holding current is vibrated in a predetermined amplitude,
abnormality diagnosis means adapted to determine presence/absence
of the abnormality in at least one of the drain switching valve and
the one-way valve based upon a changing degree of the VTC
displacement angle due to the vibration of the holding current.
22. A diagnosis device for a vane-type variable valve timing
controller according to claim 21, wherein: the hydraulic switching
valve is integral with the hydraulic control valve.
23. A diagnosis device for a vane-type variable valve timing
controller according to claim 21, wherein: the abnormality
diagnosis means sets an amplitude and a cycle in the vibration of
the holding current so that a changing degree of the VTC
displacement angle at a normal operation is within a range of an
allowance changing amount in the VTC displacement angle during a
usual holding operating.
24. A diagnosis device for a vane-type variable valve timing
controller according to claim 21, wherein: the abnormality
diagnosis means sets an amplitude in the vibration of the holding
current so that a changing amount of the VTC displacement angle due
to an increasing direction amplitude of the holding current is
substantially equal to a changing amount in the VTC displacement
angle due to a decreasing direction amplitude thereof.
25. A diagnosis device for a vane-type variable valve timing
controller according to claim 21, wherein: the abnormality
diagnosis means sets a cycle in the vibration of the holding
current close to the minimum time of being capable of transmitting
the hydraulic pressure to the each hydraulic chamber in an
increasing direction amplitude and a decreasing direction amplitude
of the holding current in consideration of a delay of a hydraulic
transmission system to the each hydraulic chamber.
26. A diagnosis device for a vane-type variable valve timing
controller according to claim 21, wherein: the abnormality
diagnosis means starts the vibration of the holding current after a
predetermined time elapses from start of the holding operation and
determines presence/absence of the abnormality by performing the
vibration of the holding current for a predetermine time.
27. A diagnosis device for a vane-type variable valve timing
controller according to claim 21, further comprising: holding
current learning means for learning the holding current, wherein:
the abnormality diagnosis means vibrates the holding current
centered at a holding current learning value learned by the holding
current learning means.
28. A diagnosis device for a vane-type variable valve timing
controller according to claim 21, wherein: the each drain switching
valve is structured in such a manner as to be all the time opened
in a region of a high rotational side where an engine generated
hydraulic pressure is high; and in a region of a low rotational
side where both of the drain switching valves are closed, the
abnormality diagnosis means determines whether or not there occurs
an open abnormality state where at least one of the drain switching
valve and the one-way valve in the side of the advance hydraulic
chamber or the retard hydraulic chamber remains to be opened, based
upon whether or not a changing degree of the VTC displacement angle
exceeds a predetermined abnormality determination threshold value
to increase in an advance or a retard direction, and in a region of
a high rotational side where both of the drain switching valves are
opened, the abnormality diagnosis means determines whether or not
there occurs a closed abnormality state where the drain switching
valve in the side of the advance hydraulic chamber or the retard
hydraulic chamber remains to be closed, based upon whether or not a
changing degree of the VTC displacement angle exceeds a
predetermined abnormality determination threshold value to increase
in an advance or a retard direction.
29. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a first one-way
valve disposed in a hydraulic supply passage of the advance
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the
advance hydraulic chamber; a first drain control valve disposed in
a first drain oil passage bypassing the first one-way valve and
driven by hydraulic pressure; a second one-way valve disposed in a
hydraulic supply passage of the retard hydraulic chamber in at
least one of the vane accommodating chambers for preventing reverse
flow of operating oil from the retard hydraulic chamber; a second
drain control valve disposed in a second drain oil passage
bypassing the second one-way valve and driven by the hydraulic
pressure; a first hydraulic control valve for controlling the
hydraulic pressure supplied to the variable valve timing
controller; a second hydraulic control valve for controlling the
hydraulic pressure driving the first and second drain control
valves, wherein: during hold operating of holding a displacement
angle of the variable valve timing controller (hereinafter,
referred to as VTC displacement angle) to a target displacement
angle, both the drain control valves in a side of the advance
hydraulic chamber and a side of the retard hydraulic chamber are
closed to effectively function both the one-way valves in the side
of the advance hydraulic chamber and the side of the retard
hydraulic chamber; thereby, the second hydraulic control valve is
controlled to prevent reverse flow of the operating oil from the
advance hydraulic chamber and the retard hydraulic chamber and also
a control current of the first hydraulic control valve controlling
the hydraulic pressure supplied to the variable valve timing
controller is controlled to a predetermined holding current; during
advance/retard operating of displacing the VTC displacement angle
to the advance direction or the retard direction, either one of the
drain control valves in the side of the advance hydraulic chamber
and the side of the retard hydraulic chamber is opened in
accordance with the displacement direction to control the second
hydraulic control valve so that either one of the one-way valves
does not operate; and the control current of the first hydraulic
control valve is controlled to vary the hydraulic pressure supplied
to the variable valve timing controller, displacing the VTC
displacement angle toward the target displacement angle, further
comprising: when at the time of meeting a predetermined abnormality
diagnosis execution condition during the advance/retard operating,
the holding current is vibrated in a predetermined amplitude,
abnormality diagnosis means adapted to determine presence/absence
of abnormality in at least one of the drain control valve and the
one-way valve based upon a changing rate of the VTC displacement
angle due to the vibration of the holding current.
30. A diagnosis device for a vane-type variable valve timing
controller according to claim 29, wherein: a shaft for driving the
first hydraulic control valve is integral with a shaft for driving
the second hydraulic control valve.
31. A diagnosis device for a vane-type variable valve timing
controller according to claim 29, wherein: the abnormality
diagnosis means sets an amplitude and a cycle in the vibration of
the holding current so that a changing degree of the VTC
displacement angle at a normal operation is within a range of an
allowance changing amount in the VTC displacement angle during a
usual holding operating.
32. A diagnosis device for a vane-type variable valve timing
controller according to claim 29, wherein: the abnormality
diagnosis means sets an amplitude in the vibration of the holding
current so that a changing amount of the VTC displacement angle due
to an increasing direction amplitude of the holding current is
substantially equal to a changing amount in the VTC displacement
angle due to a decreasing direction amplitude thereof
33. A diagnosis device for a vane-type variable valve timing
controller according to claim 29, wherein: the abnormality
diagnosis means sets a cycle in the vibration of the holding
current close to the minimum time of being capable of transmitting
the hydraulic pressure to the each hydraulic chamber in an
increasing direction amplitude and a decreasing direction amplitude
of the holding current in consideration of a delay of a hydraulic
transmission system supplying the hydraulic pressure to the
variable valve timing controller.
34. A diagnosis device for a vane-type variable valve timing
controller according to claim 29, wherein: the abnormality
diagnosis means starts the vibration of the holding current after a
predetermined time elapses from start of the holding operation and
determines presence/absence of the abnormality by performing the
vibration of the holding current for a predetermine time.
35. A diagnosis device for a vane-type variable valve timing
controller according to claim 29, further comprising: holding
current learning means for learning the holding current, wherein:
the abnormality diagnosis means vibrates the holding current
centered at a holding current learning value learned by the holding
current learning means.
36. A diagnosis device for a vane-type variable valve timing
controller according to claim 29, wherein: the each drain control
valve is structured in such a manner as to be all the time opened
in a region of a high rotational side where an engine generated
hydraulic pressure is high; and in a region of a low rotational
side where both of the drain control valves are closed at a normal
operation, the abnormality diagnosis means determines whether or
not there occurs an open abnormality state where at least one of
the drain control valve and the one-way valve in the side of the
advance hydraulic chamber or the retard hydraulic chamber remains
to be opened, based upon whether or not a changing degree of the
VTC displacement angle exceeds a predetermined abnormality
determination threshold value to increase in an advance or a retard
direction, and in a region of a high rotational side where both of
the drain control valves are opened at a normal operation, the
abnormality diagnosis means determines whether or not there occurs
a closed abnormality state where the drain control valve in the
side of the advance hydraulic chamber or the retard hydraulic
chamber remains to be closed, based upon whether or not a changing
degree of the VTC displacement angle exceeds a predetermined
abnormality determination threshold value to increase in an advance
or a retard direction.
37. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a first one-way
valve disposed in a hydraulic supply passage of the advance
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the
advance hydraulic chamber; a first drain control valve disposed in
a first drain oil passage bypassing the first one-way valve and
driven by hydraulic pressure; a second one-way valve disposed in a
hydraulic supply passage of the retard hydraulic chamber in at
least one of the vane accommodating chambers for preventing reverse
flow of operating oil from the retard hydraulic chamber; a second
drain control valve disposed in a second drain oil passage
bypassing the second one-way valve and driven by the hydraulic
pressure; a single first hydraulic control valve for controlling
the hydraulic pressure supplied to the first and second drain
control valves and the variable valve timing controller; wherein:
during holding operating of holding a displacement angle of the
variable valve timing controller (hereinafter, referred to as VTC
displacement angle) to a target displacement angle, a control
current of the hydraulic control valve is controlled to a
predetermined holding current to close both the drain control
valves in a side of the advance hydraulic chamber and a side of the
retard hydraulic chamber to effectively function both the one-way
valves in the side of the advance hydraulic chamber and the side of
the retard hydraulic chamber; thereby preventing reverse flow of
the operating oil from the advance hydraulic chamber and the retard
hydraulic chamber and also controlling the hydraulic pressure
supplied to the variable valve timing controller; during
advance/retard operating of displacing the VTC displacement angle
to the advance direction or the retard direction, the control
current of the hydraulic control valve is controlled to open either
one of the drain control valves in the side of the advance
hydraulic chamber and the side of the retard hydraulic chamber in
accordance with the displacement direction so that either one of
the one-way valves does not operate; and further, the hydraulic
pressure supplied to the variable valve timing controller is
varied, thereby displacing the VTC displacement angle toward the
target displacement angle, further comprising: when at the time of
meeting a predetermined abnormality diagnosis execution condition
during the advance/retard operating, the holding current is
vibrated in a predetermined amplitude, abnormality diagnosis means
adapted to determine presence/absence of abnormality in at least
one of the drain control valve and the one-way valve based upon a
changing degree of the VTC displacement angle due to the vibration
of the holding current.
38. A diagnosis device for a vane-type variable valve timing
controller according to claim 37, wherein: the abnormality
diagnosis means sets an amplitude and a cycle in the vibration of
the holding current so that a changing degree of the VTC
displacement angle at a normal operation is within a range of an
allowance changing amount in the VTC displacement angle during a
usual holding operating.
39. A diagnosis device for a vane-type variable valve timing
controller according to claim 37, wherein: the abnormality
diagnosis means sets an amplitude in the vibration of the holding
current so that a changing amount of the VTC displacement angle due
to an increasing direction amplitude of the holding current is
substantially equal to a changing amount in the VTC displacement
angle due to a decreasing direction amplitude thereof
40. A diagnosis device for a vane-type variable valve timing
controller according to claim 37, wherein: the abnormality
diagnosis means sets a cycle in the vibration of the holding
current close to the minimum time of being capable of transmitting
the hydraulic pressure to the each hydraulic chamber in an
increasing direction amplitude and a decreasing direction amplitude
of the holding current in consideration of a delay of a hydraulic
transmission system supplying the hydraulic pressure to the
variable valve timing controller.
41. A diagnosis device for a vane-type variable valve timing
controller according to claim 37, wherein: the abnormality
diagnosis means starts the vibration of the holding current after a
predetermined time elapses from start of the holding operation and
determines presence/absence of the abnormality by performing the
vibration of the holding current for a predetermine time.
42. A diagnosis device for a vane-type variable valve timing
controller according to claim 37, further comprising: holding
current learning means for learning the holding current, wherein:
the abnormality diagnosis means vibrates the holding current
centered at a holding current learning value learned by the holding
current learning means.
43. A diagnosis device for a vane-type variable valve timing
controller according to claim 37, wherein: the each drain control
valve is structured in such a manner as to be all the time opened
in a region of a high rotational side where an engine generated
hydraulic pressure is high; and in a region of a low rotational
side where both of the drain control valves are closed at a normal
operation, the abnormality diagnosis means determines whether or
not there occurs an open abnormality state where at least one of
the drain control valve and the one-way valve in the side of the
advance hydraulic chamber or the retard hydraulic chamber remains
to be opened based upon whether or not a changing degree of the VTC
displacement angle exceeds a predetermined abnormality
determination threshold value to increase in an advance or a retard
direction, and in a region of a high rotational side where both of
the drain control valves are opened at a normal operation, the
abnormality diagnosis means determines whether or not there occurs
a closed abnormality state where the drain control valve in the
side of the advance hydraulic chamber or the retard hydraulic
chamber remains to be closed based upon whether or not a changing
degree of the VTC displacement angle exceeds a predetermined
abnormality determination threshold value to increase in an advance
or retard direction.
44. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a one-way valve
disposed in each of a hydraulic supply passage of the advance
hydraulic chamber and a hydraulic supply passage of the retard
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the each
hydraulic chamber; a drain oil passage disposed in parallel to the
hydraulic supply passage of the each hydraulic chamber for
bypassing the one-way valve; a drain switching valve disposed in
the each drain oil passage and driven by hydraulic pressure; and a
hydraulic switching valve switching the hydraulic pressure driving
the each drain switching valve, wherein: during hold operating of
holding a displacement angle of the variable valve timing
controller (hereinafter, referred to as VTC displacement angle) to
a target displacement angle, both the drain switching valves in a
side of the advance hydraulic chamber and a side of the retard
hydraulic chamber are closed to effectively function both the
one-way valves in the side of the advance hydraulic chamber and the
side of the retard hydraulic chamber; thereby, the hydraulic
switching valve is controlled to prevent reverse flow of the
operating oil from both the hydraulic chambers and also a control
current of the hydraulic control valve controlling the hydraulic
pressure in the each hydraulic chamber is controlled to a
predetermined holding current; during advance/retard operating of
displacing the VTC displacement angle to the advance direction or
the retard direction, either one of the drain switching valves in
the side of the advance hydraulic chamber and the of the retard
hydraulic chamber side is opened in accordance with the
displacement direction to control the hydraulic switching valve so
that either one of the one-way valves does not operate; and
further, the control current of the hydraulic control valve is
controlled to vary the hydraulic pressure in the each hydraulic
chamber, displacing the VTC displacement angle toward the target
displacement angle, further comprising: abnormality diagnosis means
adapted to determine whether or not there occurs an open
abnormality state where at least one of the drain switching valve
and the one-way valve remains to be opened, based upon a changing
amount of the VTC displacement angle within a predetermined period
during the holding operating.
45. A diagnosis device for a vane-type variable valve timing
controller according to claim 44, wherein: the abnormality
diagnosis means calculates a difference between a VTC displacement
angle immediately after start of the holding operation and a VTC
displacement angle at elapse of the predetermined period to
determine presence/absence of the open abnormality state in at
least one of the drain switching valve and the one-way valve based
upon this difference.
46. A diagnosis device for a vane-type variable valve timing
controller according to claim 44, wherein: the abnormality
diagnosis means detects a maximum value and a minimum value of a
VTC displacement angle from a point immediately after start of the
holding operation until a point at elapse of the predetermined
period to calculate a difference between the maximum value and the
minimum value, determining presence/absence of the open abnormality
state in at least one of the drain switching valve and the one-way
valve based upon this difference.
47. A diagnosis device for a vane-type variable valve timing
controller according to claim 44, wherein: the abnormality
diagnosis means detects a maximum value and a minimum value of a
VTC displacement angle from a point immediately after start of the
holding operation until a point at elapse of the predetermined
period to calculate a deviation between a target displacement angle
during the holding operating and the maximum value and a deviation
between the target displacement angle and the minimum value,
determining presence/absence of the open abnormality state in at
least one of the drain switching valve and the one-way valve based
upon these two deviations.
48. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a one-way valve
disposed in each of a hydraulic supply passage of the advance
hydraulic chamber and a hydraulic supply passage of the retard
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the each
hydraulic chamber; a drain oil passage disposed in parallel to the
hydraulic supply passage of the each hydraulic chamber for
bypassing the one-way valve; a drain switching valve disposed in
the each drain oil passage and driven by hydraulic pressure; and a
hydraulic switching valve for switching the hydraulic pressure
driving the each drain switching valve, wherein: during hold
operating of holding a displacement angle of the variable valve
timing controller (hereinafter, referred to as VTC displacement
angle) to a target displacement angle, both the drain switching
valves in a side of the advance hydraulic chamber and a side of the
retard hydraulic chamber are closed to effectively function both
the one-way valves in the side of the advance hydraulic chamber and
the side of the retard hydraulic chamber; thereby, the hydraulic
switching valve is controlled to prevent reverse flow of the
operating oil from both the hydraulic chambers and also a control
current of the hydraulic control valve controlling the hydraulic
pressure in the each hydraulic chamber is controlled to a
predetermined holding current; during advance/retard operating of
displacing the VTC displacement angle to the advance direction or
the retard direction, either one of the drain switching valves in
the side of the advance hydraulic chamber and the side of the
retard hydraulic chamber side is opened in accordance with the
displacement direction to control the hydraulic switching valve so
that either one of the one-way valves does not operate; and
further, the control current of the hydraulic control valve is
controlled to vary the hydraulic pressure in the each hydraulic
chamber, displacing the VTC displacement angle toward the target
displacement angle, further comprising: abnormality diagnosis means
determines a convergent state to the target displacement angle of
the VTC displacement angle at changing the target displacement
angle to determine whether or not there occurs a closed abnormality
state where the drain switching valve remains to be closed, based
upon the convergent state.
49. A diagnosis device for a vane-type variable valve timing
controller according to claim 48, wherein: the abnormality
diagnosis means measures, as data representing the convergent
state, continuing time of a state where a deviation between the
target displacement angle and the VTC displacement angle is more
than a predetermined value to determine presence/absence of the
closed abnormality state in the drain switching valve based upon
this continuing time.
50. A diagnosis device for a vane-type variable valve timing
controller according to claim 48, wherein: the abnormality
diagnosis means measures, as data representing the convergent
state, elapse time from a point where a deviation between the
target displacement angle and the VTC displacement angle is more
than a first predetermined value until a point where the deviation
is less than a second predetermined value smaller than the first
predetermined value to determine presence/absence of the closed
abnormality state in the drain switching valve based upon this
elapse time.
51. A diagnosis device for a vane-type variable valve timing
controller according to claim 48, wherein: the abnormality
diagnosis means determines the convergent state by setting as a
precondition that a supply hydraulic pressure to the hydraulic
control valve is more than a predetermined value.
52. A diagnosis device for a vane-type variable valve timing
controller according to claim 51, wherein: the abnormality
diagnosis means determines whether or not the supply hydraulic
pressure to the hydraulic control valve is more than the
predetermined value, based upon information regarding at least one
of an engine rotational speed and an oil temperature.
53. A diagnosis device for a vane-type variable valve timing
controller according to claim 44, wherein: the hydraulic switching
valve is integral with the hydraulic control valve.
54. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a first one-way
valve disposed in a hydraulic supply passage of the advance
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the
advance hydraulic chamber; a first drain control valve disposed in
a first drain oil passage bypassing the first one-way valve and
driven by hydraulic pressure; a second one-way valve disposed in a
hydraulic supply passage of the retard hydraulic chamber in at
least one of the vane accommodating chambers for preventing reverse
flow of operating oil from the retard hydraulic chamber; a second
drain control valve disposed in a second drain oil passage
bypassing the second one-way valve and driven by hydraulic
pressure; a first hydraulic control valve for controlling the
hydraulic pressure supplied to the variable valve timing
controller; a second hydraulic control valve for controlling the
hydraulic pressure driving the first and second drain control
valves, wherein: during hold operating of holding a displacement
angle of the variable valve timing controller (hereinafter,
referred to as VTC displacement angle) to a target displacement
angle, both the drain control valves in a side of the advance
hydraulic chamber and a side of the retard hydraulic chamber are
closed to effectively function both the one-way valves in the side
of the advance hydraulic chamber and the side of the retard
hydraulic chamber; thereby, the second hydraulic control valve is
controlled to prevent reverse flow of the operating oil from the
advance hydraulic chamber and the retard hydraulic chamber and also
a control current of the first hydraulic control valve controlling
the hydraulic pressure supplied to the variable valve timing
controller is controlled to a predetermined holding current; during
advance/retard operating of displacing the VTC displacement angle
to the advance direction or the retard direction, either one of the
drain control valves in the side of the advance hydraulic chamber
and the side of the retard hydraulic chamber is opened in
accordance with the displacement direction to control the second
hydraulic control valve so that either one of the one-way valves
does not operate; and further, the control current of the first
hydraulic control valve is controlled to vary the hydraulic
pressure supplied to the variable valve timing controller,
displacing the VTC displacement angle toward the target
displacement angle, further comprising: abnormality diagnosis means
adapted to determine whether or not there occurs an open
abnormality state where at least one of the drain control valve and
the one-way valve remains to be opened, based upon a changing
amount of the VTC displacement angle within a predetermined period
during the holding operating.
55. A diagnosis device for a vane-type variable valve timing
controller according to claim 54, wherein: the abnormality
diagnosis means calculates a difference between a VTC displacement
angle immediately after start of the holding operation and a VTC
displacement angle at elapse of the predetermined period to
determine presence/absence of the open abnormality state in at
least one of the drain control valve and the one-way valve based
upon this difference.
56. A diagnosis device for a vane-type variable valve timing
controller according to claim 54, wherein: the abnormality
diagnosis means detects a maximum value and a minimum value of a
VTC displacement angle from a point immediately after start of the
holding operation until a point at elapse of the predetermined
period to calculate a difference between the maximum value and the
minimum value, determining presence/absence of the open abnormality
state in at least one of the drain control valve and the one-way
valve based upon this difference.
57. A diagnosis device for a vane-type variable valve timing
controller according to claim 54, wherein: the abnormality
diagnosis means detects a maximum value and a minimum value of a
VTC displacement angle from a point immediately after start of the
holding operation until a point at elapse of the predetermined
period to calculate a deviation between a target displacement angle
during the holding operating and the maximum value and a deviation
between the target displacement angle and the minimum value,
determining presence/absence of the open abnormality state in at
least one of the drain control valve and the one-way valve based
upon these two deviations.
58. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a first one-way
valve disposed in a hydraulic supply passage of the advance
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the
advance hydraulic chamber; a first drain control valve disposed in
a first drain oil passage bypassing the first one-way valve and
driven by hydraulic pressure; a second one-way valve disposed in a
hydraulic supply passage of the retard hydraulic chamber in at
least one of the vane accommodating chambers for preventing reverse
flow of operating oil from the retard hydraulic chamber; a second
drain control valve disposed in a second drain oil passage
bypassing the second one-way valve and driven by the hydraulic
pressure; a first hydraulic control valve for controlling the
hydraulic pressure supplied to the variable valve timing
controller; a second hydraulic control valve for controlling the
hydraulic pressure driving the first and second drain control
valves, wherein: during hold operating of holding a displacement
angle of the variable valve timing controller (hereinafter,
referred to as VTC displacement angle) to a target displacement
angle, both the drain control valves in a side of the advance
hydraulic chamber and a side of the retard hydraulic chamber are
closed to effectively function both the one-way valves in the side
of the advance hydraulic chamber and the side of the retard
hydraulic chamber; thereby, the second hydraulic control valve is
controlled to prevent reverse flow of the operating oil from the
advance hydraulic chamber and the retard hydraulic chamber and also
a control current of the first hydraulic control valve controlling
the hydraulic pressure supplied to the variable valve timing
controller is controlled to a predetermined holding current; during
advance/retard operating of displacing the VTC displacement angle
to the advance direction or the retard direction, either one of the
drain control valves in the side of the advance hydraulic chamber
and the side of the retard hydraulic chamber is opened in
accordance with the displacement direction to control the second
hydraulic control valve so that either one of the one-way valves
does not operate; and further, the control current of the first
hydraulic control valve is controlled to vary the hydraulic
pressure supplied to the variable valve timing controller,
displacing the VTC displacement angle toward the target
displacement angle, further comprising: abnormality diagnosis means
determines a convergent state to the target displacement angle of
the VTC displacement angle at changing the target displacement
angle to determine whether or not there occurs a closed abnormality
state where the drain control valve remains to be closed, based
upon the convergent state.
59. A diagnosis device for a vane-type variable valve timing
controller according to claim 58, wherein: the abnormality
diagnosis means measures, as data representing the convergent
state, continuing time of a state where a deviation between the
target displacement angle and the VTC displacement angle is more
than a predetermined value to determine presence/absence of the
closed abnormality state in the drain control valve based upon this
continuing time.
60. A diagnosis device for a vane-type variable valve timing
controller according to claim 58, wherein: the abnormality
diagnosis means measures, as data representing the convergent
state, elapse time from a point where a deviation between the
target displacement angle and the VTC displacement angle is more
than a first predetermined value until a point where the deviation
is less than a second predetermined value smaller than the first
predetermined value to determine presence/absence of the closed
abnormality state in the drain control valve based upon this elapse
time.
61. A diagnosis device for a vane-type variable valve timing
controller according to claim 58, wherein: the abnormality
diagnosis means determines the convergent state by setting as a
precondition that a supply hydraulic pressure to the hydraulic
control valve is more than a predetermined value.
62. A diagnosis device for a vane-type variable valve timing
controller according to claim 61, wherein: the abnormality
diagnosis means determines whether or not the supply hydraulic
pressure to the hydraulic control valve is more than the
predetermined value, based upon information regarding at least one
of an engine rotational speed and an oil temperature.
63. A diagnosis device for a vane-type variable valve timing
controller according to claim 54, wherein: a shaft for driving the
first hydraulic control valve is integral with a shaft for driving
the second hydraulic control valve.
64. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a first one-way
valve disposed in a hydraulic supply passage of the advance
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the
advance hydraulic chamber; a first drain control valve disposed in
a first drain oil passage bypassing the first one-way valve and
driven by hydraulic pressure; a second one-way valve disposed in a
hydraulic supply passage of the retard hydraulic chamber in at
least one of the vane accommodating chambers for preventing reverse
flow of operating oil from the retard hydraulic chamber; a second
drain control valve disposed in a second drain oil passage
bypassing the second one-way valve and driven by the hydraulic
pressure; a single first hydraulic control valve for controlling
the hydraulic pressure supplied to the first and second drain
control valves and the variable valve timing controller; wherein:
during hold operating of holding a displacement angle of the
variable valve timing controller (hereinafter, referred to as VTC
displacement angle) to a target displacement angle, a control
current of the hydraulic control valve is controlled to a
predetermined holding current to close both the drain control
valves in a side of the advance hydraulic chamber and a side of the
retard hydraulic chamber to effectively function both the one-way
valves in the side of the advance hydraulic chamber and the side of
the retard hydraulic chamber; thereby preventing reverse flow of
the operating oil from the advance hydraulic chamber and the retard
hydraulic chamber and also controlling the hydraulic pressure
supplied to the variable valve timing controller; during
advance/retard operating of displacing the VTC displacement angle
to the advance direction or the retard direction, the control
current of the hydraulic control valve is controlled to open either
one of the drain control valves in the side of the advance
hydraulic chamber and the side of the retard hydraulic chamber in
accordance with the displacement direction so that either one of
the one-way valves does not operate; and further, the hydraulic
pressure supplied to the variable valve timing controller is
varied, thereby displacing the VTC displacement angle toward the
target displacement angle, further comprising: abnormality
diagnosis means adapted to determine whether or not there occurs an
open abnormality state where at least one of the drain control
valve and the one-way valve remains to be opened, based upon a
changing amount of the VTC displacement angle within a
predetermined period during the holding operating.
65. A diagnosis device for a vane-type variable valve timing
controller according to claim 64, wherein: the abnormality
diagnosis means calculates a difference between a VTC displacement
angle immediately after start of the holding operation and a VTC
displacement angle at elapse of the predetermined period to
determine presence/absence of the open abnormality state in at
least one of the drain control valve and the one-way valve based
upon this difference.
66. A diagnosis device for a vane-type variable valve timing
controller according to claim 64, wherein: the abnormality
diagnosis means detects a maximum value and a minimum value of a
VTC displacement angle from a point immediately after start of the
holding operation until a point at elapse of the predetermined
period to calculate a difference between the maximum value and the
minimum value, determining presence/absence of the open abnormality
state in at least one of the drain control valve and the one-way
valve based upon this difference.
67. A diagnosis device for a vane-type variable valve timing
controller according to claim 64, wherein: the abnormality
diagnosis means detects a maximum value and a minimum value of a
VTC displacement angle from a point immediately after start of the
holding operation until a point at elapse of the predetermined
period to calculate a deviation between a target displacement angle
during the holding operating and the maximum value and a deviation
between the target displacement angle and the minimum value,
determining presence/absence of the open abnormality state in at
least one of the drain control valve and the one-way valve based
upon these two deviations.
68. A diagnosis device for a vane-type variable valve timing
controller in which each of a plurality of vane accommodating
chambers formed in a housing of the vane-type variable valve timing
controller is divided into an advance hydraulic chamber and a
retard hydraulic chamber by a vane comprising: a first one-way
valve disposed in a hydraulic supply passage of the advance
hydraulic chamber in at least one of the vane accommodating
chambers for preventing reverse flow of operating oil from the
advance hydraulic chamber; a first drain control valve disposed in
a first drain oil passage bypassing the first one-way valve and
driven by hydraulic pressure; a second one-way valve disposed in a
hydraulic supply passage of the retard hydraulic chamber in at
least one of the vane accommodating chambers for preventing reverse
flow of operating oil from the retard hydraulic chamber; a second
drain control valve disposed in a second drain oil passage
bypassing the second one-way valve and driven by the hydraulic
pressure; a single first hydraulic control valve for controlling
the hydraulic pressure supplied to the first and second drain
control valves and the variable valve timing controller; wherein:
during hold operating of holding a displacement angle of the
variable valve timing controller (hereinafter, referred to as VTC
displacement angle) to a target displacement angle, both the drain
switching valves in a side of the advance hydraulic chamber and a
side of the retard hydraulic chamber are closed to effectively
function both the one-way valves in the side of the advance
hydraulic chamber and the side of the retard hydraulic chamber;
thereby, the hydraulic switching valve is controlled to prevent
reverse flow of the operating oil from both the hydraulic chambers
and also a control current of the hydraulic control valve
controlling the hydraulic pressure in the each hydraulic chamber is
controlled to a predetermined holding current; during
advance/retard operating of displacing the VTC displacement angle
to the advance direction or the retard direction, either one of the
drain switching valves in the side of the advance hydraulic chamber
and the side of the retard hydraulic chamber is opened in
accordance with the displacement direction to control the hydraulic
switching valve so that either one of the one-way valves does not
operate; and further, the control current of the hydraulic control
valve is controlled to vary the hydraulic pressure in the each
hydraulic chamber, displacing the VTC displacement angle toward the
target displacement angle, further comprising: abnormality
diagnosis means determines a convergent state to the target
displacement angle of the VTC displacement angle at changing the
target displacement angle to determine whether or not there occurs
a closed abnormality state where the drain switching valve remains
to be closed, based upon the convergent state.
69. A diagnosis device for a vane-type variable valve timing
controller according to claim 68, wherein: the abnormality
diagnosis means measures, as data representing the convergent
state, continuing time of a state where a deviation between the
target displacement angle and the VTC displacement angle is more
than a predetermined value to determine presence/absence of the
closed abnormality state in the drain control valve based upon this
continuing time.
70. A diagnosis device for a vane-type variable valve timing
controller according to claim 68, wherein: the abnormality
diagnosis means measures, as data representing the convergent
state, elapse time from a point where a deviation between the
target displacement angle and the VTC displacement angle is more
than a first predetermined value until a point where the deviation
is less than a second predetermined value smaller than the first
predetermined value to determine presence/absence of the closed
abnormality state in the drain control valve based upon this elapse
time.
71. A diagnosis device for a vane-type variable valve timing
controller according to claim 68, wherein: the abnormality
diagnosis means determines the convergent state by setting as a
precondition that a supply hydraulic pressure to the hydraulic
control valve is more than a predetermined value.
72. A diagnosis device for a vane-type variable valve timing
controller according to claim 51, wherein: the abnormality
diagnosis means determines whether or not the supply hydraulic
pressure to the hydraulic control valve is more than the
predetermined value, based upon information regarding at least one
of an engine rotational speed and an oil temperature.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Applications
No. 2006-119354 filed on Apr. 24, 2006, No. 2006-122763 filed on
Apr. 27, 2006, and No. 2006-124825 filed on Apr. 28, 2006, the
disclosures of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a diagnosis system for a
vane-type variable valve timing controller in which one-way valves
are disposed in a hydraulic supply passage of an advance hydraulic
chamber and in a hydraulic supply passage of a retard hydraulic
chamber respectively for preventing reverse flow of operating oil
from the respective hydraulic chambers.
BACKGROUND OF THE INVENTION
[0003] A basic arrangement of a vane-type variable valve timing
controller is, as shown in U.S. Pat. No. 6,330,870B1, adapted in
such a manner that a housing rotating in a timed relation to a
crank shaft of an engine is disposed coaxially with a vane rotor
connected to a cam shaft of an intake valve (or exhaust valve) and
a plurality of vane-accommodating chambers formed in the housing
respectively are divided into an advance hydraulic chamber and a
retard hydraulic chamber by vanes (blade portions) at the outer
periphery of the vane rotor. In addition, the hydraulic pressure in
each hydraulic chamber is designed to be controlled by a hydraulic
control valve to rotate the vane rotor relative to the housing, so
that a displacement angle of the cam shaft (cam shaft phase) to the
crankshaft is varied to variably control valve timing.
[0004] In such vane-type variable valve timing controller, at the
time of opening/closing the intake valve or the exhaust valve
during engine operating, fluctuations of friction torque which the
cam shaft receives from the intake valve or the exhaust valve are
transmitted to the vane rotor. In consequence, torque fluctuations
in the retard direction or in the advance direction are exerted on
the vane rotor. Thereby, when the vane rotor is subjected to torque
fluctuations in the retard direction, the operating oil in the
advance hydraulic chamber is to be subjected to such pressure as to
be pushed out of the advance hydraulic chamber or when the vane
rotor is subjected to torque fluctuations in the advance direction,
the operating oil in the retard hydraulic chamber is to be
subjected to such pressure as to be pushed out of the retard
hydraulic chamber. In consequence, in a low-rotation region where
pressures supplied from a hydraulic supply source are low, even
when a displacement angle of the cam shaft is designed to be
advanced by supplying the hydraulic pressure to the advance
hydraulic chamber, the vane rotor is, as shown in a dotted line of
FIG. 3, pushed back in the retard direction due to the torque
fluctuations. As a result, the response time to a target
displacement angle of the vane rotor is longer.
[0005] In order to solve this problem, as shown in U.S. Pat. No.
6,763,791B2, a one-way valve is disposed in each of a hydraulic
supply passage of an advance hydraulic chamber and a hydraulic
supply passage of a retard hydraulic chamber for preventing reverse
flow of operating oil from the advance hydraulic chamber or the
retard hydraulic chamber. Thereby, as shown in a solid line of FIG.
3, it is considered that this one-way valve is adapted to prevent
the vane rotor from being pushed back in the reverse direction to
the direction of a target displacement angle during variable valve
timing controlling, improving responsiveness of the variable valve
timing control.
[0006] In the variable valve timing controller described in U.S.
Pat. No. 6,763,791B2, the one-way valve is disposed in each of the
hydraulic supply passage of the advance hydraulic chamber and the
hydraulic supply passage of the retard hydraulic chamber (hydraulic
introduction line) and also a returning line (hydraulic discharge
line) is disposed in parallel to the hydraulic supply passage of
each hydraulic chamber for bypassing the one-way valve. As a
result, this controller provides a structure where a function as a
line switching valve for opening/closing the returning line of each
hydraulic chamber is united to a hydraulic control valve
(spool-type electromagnetic valve) controlling the hydraulic
pressure supplied to each hydraulic chamber. Further, a control
current value of the hydraulic control valve is controlled to
control the hydraulic pressure supplied to each hydraulic chamber
and at the same time, to control the switching in opening/closing
of the returning line of each hydraulic chamber. Hereby, when the
hydraulic pressure in each hydraulic chamber is required to be
released, this controller is adapted to release the hydraulic
pressure through the returning line by opening the returning line
of the corresponding hydraulic chamber.
[0007] In this variable valve timing controller, however, an
armature in the hydraulic control valve is driven by an electric
variable force solenoid to increase the entire length of the
controller in the cam shaft direction, deteriorating the mounting
properties.
[0008] The present applicant has proposed a variable valve timing
controller having the structure where drain oil passages bypassing
one-way valves are provided with drain switching valves disposed
therein and driven by hydraulic pressures, and an electromagnetic
type hydraulic switching valve for switching the hydraulic pressure
driving each drain switching valve is disposed. Since in this
structure, the drain switching valve can be small-sized and
electrical wiring to the drain switching valve is not required, the
drain switching valve together with the one-way valve can be
downsized to be incorporated in a narrow space inside the variable
valve timing controller. Further, since the hydraulic switching
valve and the hydraulic control valve for controlling the hydraulic
pressure supplied to each hydraulic chamber in the variable valve
timing controller are not required to be mounted directly to the
cam shaft, this variable valve timing controller has an advantage
that the mounting properties thereof improve. It should be noted
that the present applicant has further improved the aforementioned
variable valve timing controller and has also proposed a variable
valve timing controller having a structure where a single hydraulic
control valve switches the hydraulic pressure driving each drain
switching valve and controls the hydraulic pressure supplied to
each hydraulic chamber in the variable valve timing controller.
[0009] It is found out during the developing process of the
variable valve timing mechanism that it has the possibility that
when an engine operates for a long term in an endurance test or the
like, foreign matter is forced to be entered into a drain switching
valve or a one-way valve or these valve bodies are stuck, so that
the drain switching valve or the one-way valve does not operate
normally (possibility that an advance/retard operation becomes
abnormal). Since this abnormality deteriorates the engine
performance, it is required to detect it as soon as possible to let
a driver to be informed of it for repair.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide a diagnosis
system of a vane-type variable valve timing controller which can
quickly detect abnormality in an advance/retard operation thereof
during engine operating.
[0011] In order to achieve the above object, the present invention
is provided with a one-way valve disposed in each of a hydraulic
supply passage of an advance hydraulic chamber and a hydraulic
supply passage of a retard hydraulic chamber in at least one of
vane accommodating chambers for preventing reverse flow of
operating oil from each hydraulic chamber, a drain oil passage
disposed in parallel to the hydraulic supply passage of each
hydraulic chamber for bypassing the one-way valve, a drain
switching valve disposed in each drain oil passage and driven by
hydraulic pressures and a hydraulic switching valve switching the
hydraulic pressure driving each drain switching valve. During hold
operating of holding a displacement angle of the variable valve
timing controller (hereinafter, referred to as VTC displacement
angle) to a target displacement angle, both drain switching valves
in a side of the advance hydraulic chamber and a side of the retard
hydraulic chamber are closed to effectively function both the
one-way valves in the side of the advance hydraulic chamber and the
side of the retard hydraulic chamber, controlling the hydraulic
switching valve so as to prevent reverse flow of the operating oil
from both the hydraulic chambers and also controlling a control
current of the hydraulic control valve controlling the hydraulic
pressure in the each hydraulic chamber to a predetermined holding
current. During advance/retard operating of displacing the VTC
displacement angle to the advance direction or the retard
direction, the drain switching valve in either one of the advance
hydraulic chamber side and the retard hydraulic chamber side is
opened in accordance with the displacement direction to control the
hydraulic switching valve so that either one of the one-way valves
does not operate. Further, the control current of the hydraulic
control valve is controlled to vary the hydraulic pressure in each
hydraulic chamber, displacing the VTC displacement angle toward the
target displacement angle. In addition, diagnosis means is adapted
to determine presence/absence of abnormality in the advance/retard
operation based upon a changing rate of the VTC displacement angle
when a predetermined abnormality diagnosis execution condition is
met during the advance/retard operating.
[0012] When the entire system is operating normally, during retard
operating, the drain switching valve in the side of the advance
hydraulic chamber is opened, making the operating oil in the
advance hydraulic chamber be easily drained through the drain
switching valve and at the same time, the drain switching valve in
the side of the retard hydraulic chamber is closed to make the
function of the one-way valve in the side of the retard hydraulic
chamber be effected well, preventing reverse flow of the operating
oil from the retard hydraulic chamber with the one-way valve, while
performing control of filling the operating oil in the retard
hydraulic chamber. Hereby, even at a low hydraulic pressure, coping
with the torque fluctuations in the advance direction transmitted
from the cam shaft, the reverse flow of the operating oil from the
retard hydraulic chamber is prevented with the one-way valve and at
the same time, the hydraulic pressure is efficiently supplied to
the retard hydraulic chamber, improving the retard
responsiveness.
[0013] In addition, during advance operating, the drain switching
valve in the side of the retard hydraulic chamber is opened, making
the operating oil in the retard hydraulic chamber be easily drained
through the drain switching valve and the drain switching valve in
the side of the advance hydraulic chamber is closed to make the
function of the one-way valve in the side of the advance hydraulic
chamber be effected well, preventing reverse flow of the operating
oil from the advance hydraulic chamber with the one-way valve,
while performing control of filling the operating oil in the
advance hydraulic chamber. Hereby, even at a low hydraulic
pressure, coping with the torque fluctuations in the retard
direction transmitted from the cam shaft, the reverse flow of the
operating oil from the advance hydraulic chamber is prevented with
the one-way valve and at the same time, the hydraulic pressure is
efficiently supplied to the advance hydraulic chamber, improving
the advance responsiveness.
[0014] In consideration of such characteristic, the present
invention determines whether or not responsiveness in an
advance/retard operation is within a normal range based upon a
changing rate of a VTC displacement angle during advance/retard
operating to determine presence/absence of abnormality in the
corresponding advance/retard operation, thereby enabling
abnormality in the advance/retard operation during engine operating
to be quickly detected.
[0015] According to the present invention, during hold operating,
when a predetermined abnormality diagnosis execution condition is
met, the holding current may be vibrated in a certain amplitude to
determine presence/absence of abnormality in the drain switching
valve and/or the one-way valve based upon a changing rate of the
VTC displacement angle by the vibration of the holding current.
[0016] When both of the drain switching valves in the side of the
advance hydraulic chamber and the side of the retard hydraulic
chamber operate normally during hold operating, both of the drain
switching valves close. Therefore, if both the one-way valves are
normal, the reverse flow-preventing function of both the one-way
valves can be effectively applied. However, when there occurs an
open abnormality state where either one of the drain switching
valves (or one-way valves) stops at a state of being opened, even
during hold operating, either one of the drain switching valves (or
one-way valves) is fixed at the state of being opened. Accordingly,
when the holding current is vibrated in a certain amplitude during
hold operating to determine a changing amount of the VTC
displacement angle due to the vibration of the holding current, if
both of the drain switching valves normally close and the function
of the one-way valve is effectively applied, leak of the hydraulic
pressure from both of the hydraulic chambers is effectively
prevented with both of the one-way valves and therefore, a changing
amount of the VTC displacement angle is reduced. When either one of
the drain switching valves (or one-way valves) is at an open
abnormality state, the hydraulic pressure in the hydraulic chamber
at a side where the open abnormality occurs is leaked through the
drain switching valve (or one-way valve) and reduced. In
consequence, a balance in hydraulic pressure between both of the
hydraulic chambers is off and it is hard to maintain the VTC
displacement angle at a constant position, so that a changing
amount of the VTC displacement angle increases. Accordingly, if the
holding current is vibrated during hold operating as in the case of
the present invention, the determination can be made as to
presence/absence of abnormality in a drain switching valve and/or a
one-way valve based upon whether or not the changing degree of the
VTC displacement angle due to the vibration of the holding current
is great. As a result, abnormality in the drain switching valve or
the one-way valve can be quickly detected.
[0017] According to the diagnosis system of the present invention,
when both of the drain switching valves (or one-way valves) in the
side of the advance hydraulic chamber and in the side of the retard
hydraulic chamber are simultaneously at an open abnormality state,
it may be hard to detect the abnormality, but probability that both
of the drain switching valves (or one-way valves) are
simultaneously abnormal is extremely small as compared to the
probability that either one of the drain switching valves (or
one-way valves) is abnormal. Therefore, abnormality in most cases
can be quickly detected by the abnormality diagnosis method of the
present invention.
[0018] Further, according to the present invention, the
determination may be made, based upon a changing amount of the VTC
displacement angle within a certain period, as to occurrence of
open abnormality where the drain switching valve and/or the one-way
valve stops at a state of being opened during holding
operating.
[0019] When both of the drain switching valves in the side of the
advance hydraulic chamber and in the side of the retard hydraulic
chamber operate normally during hold operating, both of the drain
switching valves close. Therefore, if both of the one-way valves
are normal, the reverse flow preventing function of both of the
one-way valves can be effectively applied. However, when there
occurs an open abnormality state where either one of the drain
switching valves (one-way valves) stops at a state of being opened,
even during hold operating either one of the drain switching valves
(or one-way valves) is fixed at the state of being opened.
Therefore, When either one of the drain switching valves (or
one-way valves) is at an open abnormality state during hold
operating, the hydraulic pressure in the hydraulic chamber at a
side where the open abnormality occurs is leaked through the drain
switching valve (or one-way valve) and reduced. In consequence, a
balance in hydraulic pressure between both of the hydraulic
chambers is off and it is hard to maintain the VTC displacement
angle at a constant position, so that there occurs the phenomenon
that a changing amount of the VTC displacement angle increases.
Considering this characteristic, the present invention is designed,
during hold operating, to determine whether or not open abnormality
occurs in a drain switching valve and/or a one-way valve based upon
the changing amount of the VTC displacement angle within a certain
period. As a result, open abnormality in the drain switching valve
or the one-way valve can be quickly detected.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic diagram showing a variable valve
timing controller and a hydraulic control circuit thereof. Example
1 of the present invention.
[0021] FIGS. 2A, 2B and 2C are diagrams each explaining a retard
operation, a holding operation and an advance operation in the
variable valve timing controller.
[0022] FIG. 3 is a characteristic diagram explaining a difference
in VTC response rate at advance operating depending on
presence/absence of a one-way valve.
[0023] FIG. 4 is a characteristic diagram showing one example of a
response characteristic of the variable valve timing controller
with a one-way valve.
[0024] FIG. 5 is a diagram explaining a relation between
abnormality in an advance/retard operation and open
abnormality/closed abnormality of a drain switching valve or a
one-way valve.
[0025] FIG. 6 is a flow chart explaining the process order in an
abnormality diagnosis routine.
[0026] FIG. 7 is a time chart explaining a behavior of an
abnormality diagnosis process at a point when abnormality of an
advance operation occurs.
[0027] FIG. 8 is a time chart explaining an abnormality diagnosis
method in Example 2 of the present invention.
[0028] FIG. 9 is a flow chart explaining the process order in an
abnormality diagnosis routine.
[0029] FIG. 10 is a flow chart explaining the process order in an
abnormality diagnosis routine.
[0030] FIG. 11 is a flow chart explaining the process order in an
abnormality diagnosis routine.
[0031] FIG. 12 is a flow chart explaining the process order in a
dither correction duty calculation routine.
[0032] FIG. 13 is a diagram showing one example of a map of an
increasing direction amplitude dizp of a dither in a hold duty.
[0033] FIG. 14 is a diagram showing one example of a map of a
reducing direction amplitude dizm of a dither in a hold duty.
[0034] FIG. 15 is a diagram showing one example of a map of an
amplitude direction switching time tmdiz of a dither in a hold
duty.
[0035] FIG. 16 is a time chart explaining an abnormality diagnosis
method in Example 3 of the present invention.
[0036] FIG. 17 is a time chart explaining an abnormality diagnosis
method in Example 3 of the present invention.
[0037] FIG. 18 is a flow chart explaining the process order in an
abnormality diagnosis routine in Example 3 of the present
invention.
[0038] FIG. 19 is a flow chart explaining the process order in an
abnormality diagnosis routine in Example 3 of the present
invention.
[0039] FIG. 20 is a flow chart explaining the process order in an
abnormality diagnosis routine in Example 3 of the present
invention.
[0040] FIG. 21 is a time chart explaining an abnormality diagnosis
method in Example 4 of the present invention.
[0041] FIG. 22 is a flow chart explaining the process order in an
abnormality diagnosis routine in Example 4 of the present
invention.
[0042] FIG. 23 is a flow chart explaining the process order in an
abnormality diagnosis routine in Example 4 of the present
invention.
[0043] FIG. 24 is a schematic diagram showing a variable valve
timing controller and a hydraulic control circuit thereof in
Example 5 of the present invention.
[0044] FIG. 25 is a schematic diagram showing a variable valve
timing controller and a hydraulic control circuit thereof in
Example 6 of the present invention.
DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENT
Embodiment 1
[0045] First, a structure of a vane-type variable valve timing
controller 11 will be explained with reference to FIG. 1. A housing
12 of the variable valve timing controller 11 is clamped and fixed
to a sprocket rotatably supported at an outer periphery of a cam
shaft in an intake side or an exhaust side (not shown) by bolts 13.
In consequence, rotation of a crankshaft for an engine is
transmitted through a timing chain to the sprocket and the housing
12 and the sprocket and the housing 12 rotate in a timed relation
to the crankshaft. A vane rotor 14 is accommodated inside the
housing 12 so as to rotate relative thereto and is clamped and
fixed to one end of the camshaft by a bolt 15.
[0046] A plurality of vane accommodating chambers 16 for
accommodating a plurality of vanes 17 at an outer periphery of the
vane rotor 14 so as to rotate in the advance direction or the
retard direction relative to the housing 12 are defined inside the
housing 12 and each vane accommodating chamber 16 is divided into
an advance hydraulic chamber 18 and a retard hydraulic chamber
19.
[0047] At a state where a hydraulic pressure beyond a predetermined
pressure is supplied to the advance hydraulic chamber 18 and the
retard hydraulic chamber 19, the vane 17 is held by the hydraulic
pressures in the advance hydraulic chamber 18 and the retard
hydraulic chamber 19 to transmit rotation of the housing 12 caused
by rotation of the crank shaft to the vane rotor 14 through the
hydraulic pressures, thereby rotating the cam shaft integrally with
the vane rotor 14. During engine operating, the hydraulic pressures
in the advance hydraulic chamber 18 and the retard hydraulic
chamber 19 are controlled by a hydraulic control valve 21 to rotate
the vane rotor 14 relative to the housing 12, thereby controlling a
displacement angle of the cam shaft (cam shaft phase) to the crank
shaft to vary valve timing of an intake valve (or exhaust
valve).
[0048] In addition, stoppers 22 and 23 for controlling a relative
rotational range of the vane rotor 14 to the housing 12 are formed
at both side portions of either one of the vanes 17, and the
maximum retard position and the maximum advance position of the
displacement angle of the cam shaft (cam shaft phase) are
restricted by the stoppers 22 and 23. In addition, either one of
the vanes 17 is provided with a lock pin 24 disposed therein for
locking a changing angle of the cam shaft at a certain lock
position at engine stopping or the like. This lock pin 24 is
inserted into a lock hole (not shown) disposed in the housing 12,
causing the changing angle of the camshaft to be locked at a
certain lock position. This lock position is set to a position
suitable for engine startup (for example, substantially
intermediate position within an adjustment possible range of a
changing angle of the cam shaft).
[0049] Oil inside an oil pan 26 (operating oil) is supplied to a
hydraulic control circuit of the variable valve timing controller
11 through the hydraulic control valve 21 by an oil pump 27. The
hydraulic control circuit includes a hydraulic supply oil passage
28 supplying oil discharged from an advance pressure port of the
hydraulic control valve 21 to a plurality of advance hydraulic
chambers 18 and a hydraulic supply oil passage 29 supplying oil
discharged from a retard pressure port of the hydraulic control
valve 21 to a plurality of retard hydraulic chambers 19.
[0050] Further, One-way valves 30 and 31 are disposed in the
hydraulic supply oil passage 28 of the advance hydraulic chamber 18
and the hydraulic supply oil passage 29 of the retard hydraulic
chamber 19 for preventing reverse flow of the operating oil from
the respective chambers 18 and 19. In the present embodiment, the
one-way valves 30 and 31 are disposed in the hydraulic control oil
passages 28 and 29 of the advance hydraulic chamber 18 and the
retard hydraulic chamber 19 in the single vane accommodating
chamber 16 only.
[0051] The one-way valves 30 and 31 may be disposed in the
hydraulic control oil passages 28 and 29 of the advance hydraulic
chamber 18 and the retard hydraulic chamber 19 in each of a
plurality of the vane accommodating chambers 16 without
mentioning.
[0052] Drain oil passage 32 and 33 for bypassing the one-way valves
30 and 31 respectively are disposed in parallel in the hydraulic
supply oil passages 28 and 29 of the respective chambers 18 and 19,
and drain switching valves 34 and 35 are disposed in the drain oil
passages 32 and 33 respectively. The drain switching valves 34 and
35 respectively are formed of spool valves driven in a closing
direction by hydraulic pressure (pilot pressure) supplied from the
hydraulic control valve 21. When the hydraulic pressure is not
applied, the drain switching valves 34 and 35 are held in an
opening position. When the drain switching valves 34 and 35 are
opened, the drain oil passages 32 and 33 are opened, causing
functions of the one-way valves 30 and 31 to be stopped. When the
drain switching valves 34 and 35 are closed, the drain oil passages
32 and 33 are closed, causing functions of the one-way valves 30
and 31 to be effectively performed. Therefore, the reverse flow of
the oil from the hydraulic chambers 18 and 19 is prevented,
maintaining the hydraulic pressures in the hydraulic chambers 18
and 19.
[0053] The drain switching valves 34 and 35 respectively do not
require electrical wiring and therefore, are downsized to be
incorporated in the vane rotor 14 inside the variable valve timing
controller 11, together with the one-way valves 30 and 31. In
consequence, the drain switching valves 34 and 35 are located near
the hydraulic chambers 18 and 19 respectively and are adapted to
open/close the respective drain oil passages 32 and 33 near the
respective hydraulic chambers 18 and 19 at advance/retard operating
in good response.
[0054] Further, in the present embodiment, considering that the
entire variable valve timing controller 11 rotates along with
rotation of the crank shaft during engine operating to apply a
rotational centrifugal force to the respective drain switching
valves 34 and 35, a mounting direction of each of the drain
switching valves 34 and 35 to the vane rotor 14 is set in such a
manner as to exert the rotational centrifugal force in the opening
direction of the valve body. Thereby, in a region of a
high-rotation side where an engine rotational speed is more than a
predetermined value, the drain switching valves respectively are
forcibly opened due to the rotational centrifugal force all the
time regardless of the control hydraulic pressures in the drain
switching valves 34 and 35 respectively, causing the functions of
the respective one-way valves 30 and 31 to be stopped. As a result,
the present embodiment is adapted to be capable of using, in a
region of the high-rotation side, the same control program as in
the conventional example without the one-way valves 30 and 31.
[0055] On the other hand, the hydraulic control valve 21 is formed
of a spool valve driven by a linear solenoid 36, where an
advance/retard hydraulic control valve 37 controlling the hydraulic
pressures supplied to the advance hydraulic chamber 18 and the
retard hydraulic chamber 19 is integral with the a drain switching
control valve 38 switching the hydraulic pressure driving the drain
switching valves 34 and 35 respectively. A current value (control
duty) supplied to the linear solenoid 36 of the hydraulic control
valve 21 is controlled by an engine control circuit (hereinafter
referred to as "ECU") 43.
[0056] The ECU 43 calculates actual valve timing (actual
displacement angle) of the intake valve (exhaust valve) based upon
output signals of a crank angle sensor 44 and a cam angle sensor 45
and also calculates target valve timing (target displacement angle)
of the intake valve (exhaust valve) based upon outputs of various
sensors such as an intake pressure sensor and a water temperature
sensor for detecting an engine operating condition. In addition,
the ECU 43 performs feedback control (or feedforward control) of a
control current value of the hydraulic control valve 21 in the
variable valve timing controller 11 so that the actual valve timing
is equal to the target valve timing. Thereby, the hydraulic
pressures in the advance hydraulic chamber 18 and the retard
hydraulic chamber 19 are controlled to rotate the vane rotor 14
relative to the housing 12, causing a displacement angle of the cam
shaft to be varied for making the actual valve timing be equal to
the target valve timing.
[0057] Here, when the intake valve or the exhaust valve is
opened/closed during engine operating, the torque fluctuation the
cam shaft receives from the intake valve or the exhaust valve is
transmitted to the vane rotor 14, causing the torque fluctuation in
the retard direction and in the advance direction to be exerted on
the vane rotor 14. In consequence; when the vane rotor 14 is
subjected to the torque fluctuation in the retard direction, the
operating oil in the advance hydraulic chamber 18 receives the
pressure to be pushed out of the advance hydraulic chamber 18 and
on the other hand, when the vane rotor 14 is subjected to the
torque fluctuation in the advance direction, the operating oil in
the retard hydraulic chamber 19 receives the pressure to be pushed
out of the retard hydraulic chamber 19. Therefore, in a
low-rotation region where a discharge hydraulic pressure of the oil
pump 27 as a hydraulic supply source is low, without the one-way
valves 30 and 31, even if the hydraulic pressure is designed to be
supplied to the advance hydraulic chamber 18 to advance a
displacement angle of the cam shaft, as shown in a dotted line of
FIG. 3, the vane rotor 14 is pushed back in the retard direction
due to the torque fluctuation, raising the problem that the
response time until the vane rotor 14 reaches a target displacement
angle is longer.
[0058] On the other hand, in the present embodiment, the one-way
valves 30 and 31 are disposed in the hydraulic supply oil passage
28 of the advance hydraulic chamber 18 and the hydraulic supply oil
passage 29 of the retard hydraulic chamber 19 for preventing
reverse flow of the operating oil from the respective chambers 18
and 19. Further, the drain oil passage 32 and 33 for bypassing the
one-way valves 30 and 31 respectively are disposed in parallel in
the hydraulic supply oil passages 28 and 29 of the respective
chambers 18 and 19, and drain switching valves 34 and 35 are
disposed in the drain oil passages 32 and 33 respectively. As a
result, as shown in FIGS. 2A, 2B and 2C, the hydraulic pressures in
the chambers 18 and 19 respectively are controlled in response to a
retard operation, a holding operation and an advance operation as
follows.
[Retard Operation]
[0059] As shown in FIG. 2A, during retard operating where the
actual valve timing is retarded toward the target valve timing in
the retard side, the hydraulic pressure is added to the drain
switching valve 34 in the advance hydraulic chamber 18 from the
hydraulic control valve 21 to open the drain switching valve 34 in
the advance hydraulic chamber 18, creating the state where the
one-way valve 30 in the advance hydraulic chamber 18 does not
function. Further, the hydraulic supply to the drain switching
valve 35 in the retard hydraulic chamber 19 is stopped to close the
drain switching valve 35 in the retard hydraulic chamber 19,
creating the state where the one-way valve 31 in the retard
hydraulic chamber 19 functions. In consequence, even at a low
hydraulic pressure, upon occurrence of the torque fluctuation in
the advance direction of the vane rotor 14, the reverse flow of oil
from retard hydraulic chamber 19 is prevented with the one-way
valve 31, while efficiently supplying the hydraulic pressure to the
retard hydraulic chamber 19, thereby to improve retard
responsiveness.
[0060] It should be noted that in the present embodiment, in a
region of a high-rotation side where an engine rotational speed is
more than a predetermined value, the drain switching valves 34 and
35 respectively are forcibly opened due to the rotational
centrifugal force all the time regardless of the control hydraulic
pressure in the drain switching valves 34 and 35 respectively,
creating the state where the functions of the respective one-way
valves 30 and 31 do not work. As a result, in a region of the
high-rotation side, even at retard operating, the drain switching
valves 34 and 35 respectively are forcibly opened due to the
rotational centrifugal force all the time, causing the functions of
the respective one-way valves 30 and 31 to be stopped. However,
since in a region of the high-rotation side, the discharge
hydraulic pressure of the oil pump 27 can be sufficiently high to
supply a sufficiently high hydraulic pressure to the retard
hydraulic chamber 19, the retard responsiveness is not
deteriorated.
[Holding Operation]
[0061] As shown in FIG. 2B, during holding operating where the
actual valve timing is held to the target valve timing, the
hydraulic supply to both of the drain switching valves 34 and 35 in
the advance hydraulic chamber 18 and in the retard hydraulic
chamber 19 is stopped to close the drain switching valves 34 and
35, creating the state where the one-way valves 30 and 31 in the
advance hydraulic chamber 18 and in the retard hydraulic chamber 19
function. In this state, even if the torque fluctuations in the
retard direction and in the advance direction are applied to the
vane rotor 14 due to the torque fluctuations the cam shaft receives
from the intake valve or the exhaust valve, the reverse flow of oil
from both of the advance hydraulic chamber 18 and the retard
hydraulic chamber 19 is prevented with the one-way valve 31 to
prevent reduction in the hydraulic pressures holding the vane 17
from both side thereof, thereby to improve holding stability.
[0062] In this holding operation also, in a region of a
high-rotation side, the drain switching valves 34 and 35
respectively are forcibly opened due to the rotational centrifugal
force, causing the state where the functions of the respective
one-way valves 30 and 31 are stopped, but since in a region of the
high-rotation side, the discharge hydraulic pressure of the oil
pump 27 can be sufficiently high to supply a sufficiently high
hydraulic pressure to both of the advance hydraulic chamber 18 and
the retard hydraulic chamber 19, the holding stability is not
reduced.
[Advance Operation]
[0063] As shown in FIG. 2C, during advance operating where the
actual valve timing is advanced toward the target valve timing in
the advance side, the hydraulic pressure supply to the drain
switching valve 34 in the advance hydraulic chamber 18 is stopped
to close the drain switching valve 34 in the advance hydraulic
chamber 18, causing the state where the one-way valve 30 in the
advance hydraulic chamber 18 functions. Further, the hydraulic
pressure from the hydraulic control valve 21 is applied to the
drain switching valve 35 in the retard hydraulic chamber 19 is
added to open the drain switching valve 35 in the retard hydraulic
chamber 19, creating the state where the one-way valve 31 in the
retard hydraulic chamber 19 does not function. In consequence, even
at a low hydraulic pressure, the reverse flow of oil from the
advance hydraulic chamber 18 upon occurrence of the torque
fluctuation in the retard direction of the vane rotor 14 is
prevented with the one-way valve 30, while efficiently supplying
the hydraulic pressure to the advance hydraulic chamber 18, thereby
to improve advance responsiveness.
[0064] In this advance operation also, in a region of a
high-rotation side, the drain switching valves 34 and 35
respectively are forcibly opened due to the rotational centrifugal
force, causing the state where the functions of the respective
one-way valves 30 and 31 are stopped, but since in a region of the
high-rotation side, the discharge hydraulic pressure of the oil
pump 27 can be sufficiently high to supply a sufficiently high
hydraulic pressure to the advance hydraulic chamber 18, the advance
responsiveness is not deteriorated.
[0065] Next, the response characteristic of the variable valve
timing controller 11 (hereinafter referred to as "VTC response
characteristic") will be explained with reference to FIG. 4. FIG. 4
shows one example of a response characteristic obtained by
measuring a relation between a control current value of the
hydraulic control valve 21 (hereinafter, referred to as "OCV
current value") and a response rate of the variable valve timing
controller 11 (hereinafter, referred to as "VTC response
rate").
[0066] In Embodiment 1, since the one-way valves 30 and 31 and the
drain switching valves 34 and 35 are disposed in both of the
advance hydraulic chamber 18 and the retard hydraulic chamber 19, a
VTC response rate does not change linearly to a change of an OCV
current value and opening/closing of the drain switching valves 34
and 35 is switched, causing the VTC rate to rapidly change at two
locations. In the VTC response characteristic of FIG. 4, the
rapidly changing point of the VTC response rate at the retard side
is a point where the drain switching valve 34 in the advance
hydraulic chamber 18 switches from closing state to opening state,
and the rapidly changing point of the VTC response rate at the
advance side is a point where the drain switching valve 35 in the
retard hydraulic chamber 19 switches from closing state to opening
state. The holding operation is made in a region where a grade of a
VTC response rate change between the rapidly changing point of the
VTC response rate at the retard side and the rapidly changing point
of the VTC response rate at the advance side is small.
[0067] Here, when the use term is long, foreign materials are
entered into the drain switching valves 34 and 35 or the one-way
valves 30 and 31 or these valve bodies are stuck, possibly
producing "an open abnormality" state where the drain switching
valves 34 and 35 or the one-way valves 30 and 31 stop at a state of
being opened or "a closed abnormality" state where the drain
switching valves 34 and 35 or the one-way valves 30 and 31 stop at
a state of being closed. Such open abnormality state is the cause
of deteriorating the engine performance and therefore, it is
required to detect it as soon as possible and inform a driver of it
for repair.
[0068] Therefore, the present embodiment is adapted to determine
whether or not the responsiveness of the advance/retard operation
is within a normal range based upon a changing rate of the VTC
displacement angle during advance/retard operating, determining
presence/absence of abnormality in the advance/retard operation.
Here, it is considered that the causes of generating abnormality of
an advance/retard operation include a case of abnormality in the
hydraulic control 21 and a case of abnormality in the drain
switching valves 34 and 35 or the one-way valves 30 and 31.
Hereinafter, the causes of generation abnormality in the
advance/retard operation will be examined.
[Cause of Generating Abnormality in an Advance Operation]
[0069] In a case where the hydraulic control valve 21 operates
normally, as causes of generating abnormality in the advance
operation, as shown in FIG. 5, the next four abnormal modes (or the
combination) are considered.
[0070] (A1) Closed Abnormality in the Drain Switching Valve 35 at
the Side of the Retard Hydraulic Chamber 19
[0071] During advance operating, there is performed control of
draining oil in the retard hydraulic chamber 19 is drained and at
the same time, filling oil into the advance hydraulic chamber 18.
However, when the drain switching valve 35 at the side of the
retard hydraulic chamber 19 is in a closed abnormality state, it is
hard to drain the oil of the retard hydraulic chamber 19.
Therefore, it is hard to fill oil into the advance hydraulic
chamber 18, causing a changing rate of the VTC displacement angle
at advance operating to be excessively slow.
[0072] (A2) Closed Abnormality in the One-Way Valve 30 at the Side
of the Advance Hydraulic Chamber 18
[0073] Since during advance operating, the drain switching valve 34
at the side of the advance hydraulic chamber 18 is closed, when the
one-way valve 30 at the side of the advance hydraulic chamber 18 is
in a closed abnormality state, the oil can not be filled into the
advance hydraulic chamber 18 at all, causing a changing rate of the
VTC displacement angle at advance operating to be excessively
slow.
[0074] (A3) Open Abnormality in the Drain Switching Valve 34 at the
Side of the Advance Hydraulic Chamber 18
[0075] When during advance operating, the drain switching valve 35
at the side of the advance hydraulic chamber 18 is in an open
abnormality state, the hydraulic pressure in the advance hydraulic
chamber 18 tends to easily flow back through the drain switching
valve 34 due to the torque fluctuation in the retard direction
transmitted from the cam shaft, causing a changing rate of the VTC
displacement angle at advance operating to be slow.
[0076] (A4) Open Abnormality in the One-Way Valve 30 at the Side of
the Advance Hydraulic Chamber 18
[0077] When during advance operating, the one-way valve 30 at the
side of the advance hydraulic chamber 18 is in an open abnormality
state, the hydraulic pressure in the advance hydraulic chamber 18
tends to easily flow back through the one-way valve 30 due to the
torque fluctuation in the retard direction transmitted from the cam
shaft, causing a changing rate of the VTC displacement angle at
advance operating to be slow.
[Cause of Generating Abnormality in a Retard Operation]
[0078] In a case where the hydraulic control valve 21 operates
normally, as causes of generating abnormality in the retard
operation, as shown in FIG. 5, the next four abnormal modes (or the
combination) are considered.
[0079] (B1) Closed Abnormality in the Drain Switching Valve 34 at
the Side of the Advance Hydraulic Chamber 18
[0080] During retard operating, there is performed control of
draining oil in the advance hydraulic chamber 18 and at the same
time, filling oil into the retard hydraulic chamber 19. However,
when the drain switching valve 34 at the side of the advance
hydraulic chamber 18 is in a closed abnormality state, it is hard
to drain the oil in the advance hydraulic chamber 18. Therefore, it
is hard to fill oil into the retard hydraulic chamber 19, causing a
changing rate of the VTC displacement angle at retard operating to
be excessively slow.
[0081] (B2) Closed Abnormality in the One-Way Valve 31 at the Side
of the Retard Hydraulic Chamber 19
[0082] Since during retard operating, the drain switching valve 35
at the side of the retard hydraulic chamber 19 is closed, when the
one-way valve 31 at the side of the retard hydraulic chamber 19 is
in a closed abnormality state, the oil can not be filled into the
retard hydraulic chamber 19 at all, causing a changing rate of the
VTC displacement angle at retard operating to be excessively
slow.
[0083] (B3) Open Abnormality in the Drain Switching Valve 35 at the
Side of the Retard Hydraulic Chamber 19
[0084] When during retard operating, the drain switching valve 35
at the side of the retard hydraulic chamber 19 is in an open
abnormality state, the oil in the retard hydraulic chamber 19 tends
to easily flow back through the drain switching valve 35 due to the
torque fluctuation in the advance direction transmitted from the
cam shaft, causing a changing rate of the VTC displacement angle at
retard operating to be slow.
[0085] (B4) Open Abnormality in the One-Way Valve 31 at the Side of
the Retard Hydraulic Chamber 19
[0086] When during retard operating, the one-way valve 31 at the
side of the retard hydraulic chamber 19 is in an open abnormality
state, the oil in the retard hydraulic chamber 19 tends to easily
flow back through the one-way valve 31 due to the torque
fluctuation in the advance direction transmitted from the cam
shaft, causing a changing rate of the VTC displacement angle at
retard operating to be slow.
[0087] Using the aforementioned determination criteria, the open
abnormality or the closed abnormality in the drain switching valves
34 and 35 or the one-way valves 30 and 31 can be determined based
upon the changing rate of the VTC displacement angle.
[0088] In the present embodiment, the ECU 43 executes an
abnormality diagnosis routine in FIG. 6. Thereby, it is determined
whether or not the responsiveness of an advance/retard operation is
within a normal range based upon a changing rate of the VTC
displacement angle during advance/retard operating, determining
presence/absence in abnormality in the advance/retard operation as
follows.
[0089] The abnormality diagnosis routine in FIG. 6 is executed at
every calculation timing of an engine rotational speed during
engine operating (for example, each of 180 degrees in a case of a
four-cylinder engine). When the present routine is activated, first
at step 101, it is determined whether or not the VTC displacement
angle is in the middle of changing (in the middle of advance or
retard operating). When the VTC displacement angle is not in the
middle of changing, the present routine ends without execution of
the subsequent processes.
[0090] On the other hand, when the VTC displacement angle is
determined at step 101 to be in the middle of changing (during
advance or retard operating), the process goes to step 102, wherein
it is determined whether or not the abnormality diagnosis execution
condition is met based upon, for example, whether or not the next
conditions (1) to (3) are all satisfied. [0091] (1) An engine
rotational speed is in a low rotation region less than a
predetermined rotational speed Ne1 (however, more than a
predetermined rotational speed Ne2 where the discharge hydraulic
pressure of the oil pump 27 is stable) [0092] (2) A deviation
between a VTC displacement angle and a target displacement angle is
more than a predetermined value. [0093] (3) In a certain time
elapse after the target displacement angle has changed. Here, the
reason for the condition (1) is that in a low rotation region where
the engine rotational speed is less than a predetermined rotational
speed Ne1, the hydraulic pressure supplied from the oil pump 27 as
the hydraulic supply source is low and therefore, when the drain
switching valves 34 and 35 or the one-way valves 30 and 31 do not
operate normally, the responsiveness at advance/retard operating
tends to significantly deteriorate, easily detecting the
abnormality. In addition, this is because there is a case where in
a region of a high rotation side, even in a case of the operation
in either one of the advance and retard directions, both of the
drain switching valves 34 and 35 in the side of the advance
hydraulic chamber 18 and in the side of the retard hydraulic
chamber 19 are adapted to be automatically opened by a rotational
centrifugal force or the like.
[0094] However, when the engine rotational speed becomes
excessively low, the discharge hydraulic pressure of the oil pump
27 becomes excessively low to reduce the responsiveness in the
advance/retard operation. Therefore, it is preferable to set the
requirement that the engine rotational speed is more than a
predetermined rotational speed Ne2 where the discharge hydraulic
pressure of the oil pump 27 can be stably obtained. Besides, since
the responsiveness in the advance/retard operation has also a
relation with viscosity of oil (oil temperature), the requirement
that the oil temperature or temperature information (for example,
engine cooling water temperature) correlating thereto is more than
a predetermined temperature may be used as the abnormality
diagnosis execution condition.
[0095] In addition, the condition (2) is made in consideration of
the characteristic of the VTC displacement angle feedback control
that when the a deviation between a VTC displacement angle and a
target displacement angle is smaller, a changing rate of the VTC
displacement is slower and is the condition required for a changing
rate of the VTC displacement angle at normal operation time to be
greater than a threshold value to be described later.
[0096] In addition, the condition (3) is made, in consideration of
the response delay by which a changing rate of the VTC displacement
angle increases with a change of a target displacement angle, for
determining a changing rate of the VTC displacement after an elapse
of a predetermined time corresponding to the maximum allowance
response delay time at a normal operation time until the changing
rate exceeds the determination threshold value to be described
later after the target displacement angle has changed.
[0097] When even one of these three conditions (1) to (3) is not
satisfied, the abnormality diagnosis execution condition is to be
not met and the present routine ends without performing the
subsequent processes.
[0098] On the other hand, when the three conditions (1) to (3) are
all satisfied, it is determined that the abnormality diagnosis
execution condition is met and the process goes to step 103,
wherein an abnormality diagnosis execution flag is set as "1"
meaning "during abnormality diagnosis executing". After that, the
process goes to step 104, wherein it is determined whether the
present VTC operating state is an advance operation or a retard
operation. As a result, when it is determined that it is the
advance operation, the process goes to step 105, wherein it is
determined whether or not the hydraulic control valve 21 is normal
by the other abnormality diagnosis function. If it is determined
that the hydraulic control valve 21 is abnormal, the present
routine ends without performing the subsequent processes.
[0099] When at step 105, it is determined that the hydraulic
control valve 21 is normal, the process goes to step 106, wherein
it is determined whether or not a changing rate in the advance
direction of the VTC displacement angle (hereinafter referred to as
"advance rate") exceeds a predetermined determination threshold
value. When the advance rate exceeds a predetermined determination
threshold value, the process goes to step 107, wherein an advance
operation abnormality determination flag is set as "0" which means
that the advance operation is normal, and the present routine
ends.
[0100] On the other hand, when at step 106, it is determined that
the advance rate is less than a determination threshold value, the
process goes to step 108, wherein there is counted up an advance
operation abnormality counter for measuring continuing time of the
state where the advance rate remains to be is less than the
determination threshold value. In addition, at next step 109, it is
determined whether or not the measurement time of the advance
operation abnormality counter (continuing time of the state where
the advance rate is less than the determination threshold value)
exceeds a predetermined time T. When it is determined that the
measurement time of the advance operation abnormality counter is
less than the predetermined time T, the present routine ends as it
is.
[0101] On the other hand, at step 109 when it is determined that
the measurement time of the advance operation abnormality counter
exceeds the predetermined time T, it is determined that the advance
operation is abnormal, the process goes to step 110, wherein the
advance operation abnormality determination flag is set as "1"
which means that the advance operation is abnormal, and the present
routine ends.
[0102] In a case where it is thus determined that the advance
operation is abnormal, it is determined that the cause of
generating the abnormality in the advance operation is, as shown in
FIG. 5, any of (A1) Closed abnormality in the drain switching valve
35 at the side of the retard hydraulic chamber 19, (A2) Closed
abnormality in the one-way valve 30 at the side of the advance
hydraulic chamber 18, (A3) Open abnormality in the drain switching
valve 34 at the side of the advance hydraulic chamber 18, and (A4)
Open abnormality in the one-way valve 30 at the side of the advance
hydraulic chamber 18.
[0103] In addition, at step 104, when it is determined that the VTC
operation state is the retard operation, the process goes to step
115, wherein it is determined whether or not the hydraulic control
valve 21 is normal by the other abnormality diagnosis function. If
it is determined that the hydraulic control valve 21 is abnormal,
the present routine ends without performing the subsequent
processes.
[0104] When at step 115, it is determined that the hydraulic
control valve 21 is normal, the process goes to step 116, wherein
it is determined whether or not a changing rate in the retard
direction of the VTC displacement angle (hereinafter referred to as
"retard rate") exceeds a predetermined determination threshold
value. When the retard rate exceeds a predetermined determination
threshold value, the process goes to step 117, wherein a retard
operation abnormality determination flag is set as "0" which means
that the retard operation is normal, and the present routine
ends.
[0105] On the other hand, when at step 116, it is determined that
the retard rate is less than a determination threshold value, the
process goes to step 118, wherein there is counted up a retard
operation abnormality counter for measuring continuing time of the
state where the retard rate remains to be is less than the
determination threshold value. In addition, at step 119, it is
determined whether or not the measurement time of the retard
operation abnormality counter (continuing time of the state where
the retard rate remains to be is less than the determination
threshold value) exceeds a predetermined time T. When it is
determined that the measurement time of the retard operation
abnormality counter is less than the predetermined time T, the
present routine ends as it is.
[0106] On the other hand, at step 119, when it is determined that
the measurement time of the retard operation abnormality counter is
less than the predetermined time T, it is determined that the
retard operation is abnormal, and the process goes to step 120,
wherein the retard operation abnormality determination flag is set
as "1" which means that the retard operation is abnormal, and the
present routine ends.
[0107] In a case where it is thus determined that the retard
operation is abnormal, it is determined that the cause of
generating the abnormality in the retard operation is, as shown in
FIG. 5, any of (B1) Closed abnormality in the drain switching valve
34 at the side of the advance hydraulic chamber 18, (B2) Closed
abnormality in the one-way valve 31 at the side of the retard
hydraulic chamber 19, (B3) Open abnormality in the drain switching
valve 35 at the side of the retard hydraulic chamber 19, and (B4)
Open abnormality in the one-way valve 31 at the side of the retard
hydraulic chamber 19.
[0108] One example of the abnormality diagnosis in the present
embodiment is shown in a time chart of FIG. 7. In the example of
FIG. 7, at time t1 a target displacement angle changes in the
advance direction and according to it, a VTC displacement angle is
feedback-controlled in such a manner as to change in the advance
direction.
[0109] At time t2 where a predetermined time elapses after the
change of the target displacement angle and the abnormality
diagnosis execution condition is met, the abnormality diagnosis
execution flag is set as "1" and the abnormality diagnosis starts.
During executing the abnormality diagnosis, the advance operation
abnormality counter measures continuing time of the state where the
retard rate remains to be less than the determination threshold
value and at time t3 where the measurement time of the advance
operation abnormality counter (continuing time of the state where
the advance rate remains to be less than the determination
threshold value) exceeds a predetermined time T, it is determined
that advance operation is abnormal, and the advance operation
abnormality determination flag is set as "1" which means that the
advance operation is abnormal.
[0110] According to the present embodiment explained above, it is
determined whether or not the responsiveness of an advance/retard
operation is within a normal range based upon a changing rate of
the VTC displacement angle during advance/retard operating, thus
determining presence/absence in abnormality in the advance/retard
operation. Therefore, during engine operating, abnormality in the
advance/retard operation, finally the drain switching valves 34 and
35 or the one-way valves 30 and 31 can be quickly detected.
[0111] It should be noted that a hydraulic switching valve for
switching the hydraulic pressure driving the drain switching valves
34 and 35 may be separated from the hydraulic control valve 21, but
the present embodiment is so structured that the hydraulic
switching valve is integral with the hydraulic control valve 21,
and therefore, has an advantage of being capable of meeting the
requirements such as reduction in the number of component parts,
reduction in costs and downsizing.
[0112] Besides, the present invention may alter the structure of
the variable valve timing controller 11 as needed and can make
various modifications within the scope of the technical spirit
thereof.
Embodiment 2
[0113] Embodiment 2 detects abnormality by using the following
method, considering that in a region of a high-rotation side where
an engine rotational speed is more than a predetermined value, the
drain switching valves 34 and 35 respectively are forcibly opened
due to the rotational centrifugal force all the time regardless of
the control hydraulic pressure in the drain switching valves 34 and
35 respectively, creating the state where the functions of the
respective one-way valves 30 and 31 do not work.
[Abnormality Diagnosis in a Region at a Low Rotation Side]
[0114] During holding operating, in a region of a low rotation side
less than a predetermined rotational speed where the drain
switching valves 34 and 35 of both the sides are closed if they are
normal, as shown in FIG. 8, the holding current (hold duty) of the
hydraulic control valve 21 is vibrated (dither) in a predetermined
amplitude/cycle to determine a changing degree of the VTC
displacement angle by the vibration of the holding current. In
addition, occurrence of an open abnormality state where the drain
switching valve 34 and/or the one-way valve 30 at the side of the
advance hydraulic chamber 18 stop at a state of being opened is
determined based upon whether or not the changing degree of the VTC
displacement angle exceeds a predetermined abnormality
determination threshold value and increases in the retard
direction.
[0115] In a case of performing the holding operation at a region of
the low rotation side, when the drain switching valves 34 and 35 at
both the sides of the advance hydraulic chamber 18 and at the side
of the retard hydraulic chamber 19 operate normally, the drain
switching valves 34 and 35 at both the sides close. Therefore, when
the drain switching valves 34 and 35 at both the sides are normal,
the reverse flow prevention functions of the drain switching valves
34 and 35 at both the sides can be effectively performed. However,
when the drain switching valve 34 and/or the one-way valve 30 at
the side of the advance hydraulic chamber 18 are in an open
abnormality state, the hydraulic pressure in the advance hydraulic
chamber 18 where the open abnormality state is occurring is leaked
through the drain switching valve 34 or the one-way valve 30 and is
reduced. Therefore, the hydraulic pressure in the retard hydraulic
chamber 19 is greater than the hydraulic pressure in the advance
hydraulic chamber 18, creating the phenomenon that the VTC
displacement angle displaces in the advance direction. Embodiment 2
uses this characteristic to detect an open abnormality state of the
drain switching valve 34 and/or the one-way valve 30 at the side of
the advance hydraulic chamber 18 based upon whether or not the
changing degree of the VTC displacement angle exceeds a
predetermined abnormality determination threshold value and
increases in the retard direction.
[0116] Likewise, occurrence of an open abnormality state where the
drain switching valve 35 and/or the one-way valve 31 at the side of
the retard hydraulic chamber 19 do not move at a state of being
opened is determined based upon whether or not the changing degree
of the VTC displacement angle by vibration of the holding current
exceeds a predetermined abnormality determination threshold value
and increases in the advance direction. This is made based upon the
following phenomenon. When the drain switching valve 35 and/or the
one-way valve 31 at the side of the retard hydraulic chamber 19 are
in an open abnormality state, the hydraulic pressure in the retard
hydraulic chamber 19 where the open abnormality state is occurring
is leaked through the drain switching valve 35 or the one-way valve
31 and is reduced. Therefore, the hydraulic pressure in the advance
hydraulic chamber 18 is greater than the hydraulic pressure in the
retard hydraulic chamber 19, creating the phenomenon that the VTC
displacement angle displaces in the retard direction. Embodiment 2
uses this characteristic to detect an open abnormality state of the
drain switching valve 35 and/or the one-way valve 31 at the side of
the retard hydraulic chamber 19.
[Abnormality Diagnosis in a Region at a High Rotation Side]
[0117] During holding operating, in a region of a high rotation
side where the drain switching valves 34 and 35 at both the sides
are forcibly opened by a rotational centrifugal force if they are
normal, creating the state where the functions of the one-way
valves 30 and 31 at both the sides are not performed, the holding
current (hold duty) of the hydraulic control valve 21 is vibrated
(dither) in a predetermined amplitude/cycle to determine a changing
degree of the VTC displacement angle by the vibration of the
holding current as in the case of a region of a low rotation side.
In addition, occurrence of a closed abnormality state where the
drain switching valve 34 at the side of the advance hydraulic
chamber 18 stops at a state of being closed is determined based
upon whether or not the changing degree of the VTC displacement
angle exceeds a predetermined abnormality determination threshold
value and increases in the advance direction.
[0118] In a case of performing the holding operation at a region of
the high rotation side, when the drain switching valves 34 and 35
at both the sides of the advance hydraulic chamber 18 and the
retard hydraulic chamber 19 operate normally, the drain switching
valves 34 and 35 at both the sides are forcibly opened by a
rotational centrifugal force. However, when the drain switching
valve 34 at the side of the advance hydraulic chamber 18 is in a
closed abnormality state, the hydraulic pressure in the advance
hydraulic chamber 18 where the closed abnormality state is
occurring relatively increases by the vibration of the holding
current. Therefore, the hydraulic pressure in the advance hydraulic
chamber 18 is greater than the hydraulic pressure in the retard
hydraulic chamber 19, creating the phenomenon that the VTC
displacement angle displaces in the advance direction. Embodiment 2
uses this characteristic to detect a closed abnormality state of
the drain switching valve 34 at the side of the advance hydraulic
chamber 18 based upon whether or not the changing degree of the VTC
displacement angle exceeds a predetermined abnormality
determination threshold value and increases in the advance
direction.
[0119] Likewise, occurrence of a closed abnormality state where the
drain switching valve 35 at the side of the retard hydraulic
chamber 19 does not move at a state of being closed is determined
based upon whether or not the changing degree of the VTC
displacement angle exceeds a predetermined abnormality
determination threshold value and increases in the retard
direction. This is made based upon the following phenomenon. When
the drain switching valve 35 at the side of the retard hydraulic
chamber 19 is in a closed abnormality state, the hydraulic pressure
in the retard hydraulic chamber 19 where the closed abnormality
state is occurring relatively increases by vibration of the holding
current. Therefore, the hydraulic pressure in the retard hydraulic
chamber 19 is greater than the hydraulic pressure in the advance
hydraulic chamber 18, creating the phenomenon that the VTC
displacement angle displaces in the retard direction. Embodiment 2
uses this characteristic to detect a closed abnormality state of
the drain switching valve 35 at the side of the retard hydraulic
chamber 19.
[0120] In addition, in the present embodiment, the amplitude and
the cycle of the vibration (dither) of the holding current during
abnormality diagnosis execution period are set in such a manner
that a changing degree of the VTC displacement angle at a normal
operation state is within a region of an allowance changing amount
of the VTC displacement angle during usual holding operating. In
this case, the holding operation is made in a region where a grade
of a VTC response rate change between a VTC response rate rapid
changing point at the retard side and a VTC response rate rapid
changing point at the advance side is small and the amplitude of
the holding current is set not to exceed the VTC response rate
rapid changing point at the retard side and the VTC response rate
rapid changing point at the advance side. In this way, in a case
where the drain switching valves 34 and 35 at both the sides are
normal, a changing amount of the VTC displacement angle during
holding operating is made within a usual allowance range even
during the vibration period of the holding current, enabling an
abnormality diagnosis without adverse influence on the engine
performance.
[0121] In this case, the amplitude of the holding current may be
set in such a manner that the increasing direction is equal to the
decreasing direction, but considering the characteristic that the
hydraulic pressure in the advance hydraulic chamber 18 easier leaks
than the hydraulic pressure in the retard hydraulic chamber 19 due
to the structure of the vane-type variable valve timing controller
11, the amplitude of the vibration of the holding current is set so
that an increasing direction amplitude (advance direction
amplitude) of the holding current is slightly greater than a
decreasing direction amplitude (retard direction amplitude) thereof
in order that a VTC displacement angle changing amount of the
increasing direction amplitude (advance direction amplitude) of the
holding current is substantially the same as the decreasing
direction amplitude (retard direction amplitude) thereof (refer to
FIGS. 13 and 14). In this way, it is possible to effectively reduce
the fluctuation of the VTC displacement angle during the vibration
period of the holding current.
[0122] In addition, the present embodiment sets a cycle (dither
cycle) of vibration of the holding current close to the minimum
time in which the hydraulic pressure can be transmitted to each
hydraulic chamber 18 and 19 in the increasing direction amplitude
and the decreasing direction amplitude of the holding current in
consideration of a delay of a hydraulic transmission system to the
hydraulic chambers 18 and 19 respectively. In this way, the VTC
displacement angle changing amount at a normal operation state is
reduced and at the same time, the VTC displacement angle changing
amount at an abnormal operation state can be increased. In
consequence, a difference in VTC displacement angle changing amount
between at a normal operation state and at an abnormal operation
state is clarified, making it possible to easily detect the
abnormality.
[0123] In addition, considering that there occurs a delay from a
point of holding operation start until a point where the VTC
displacement angle is stably held, the present embodiment, as shown
in FIG. 8, starts vibration of the holding current after a
predetermined period corresponding to the delay has elapsed from
the holding operation start and is adapted to perform an
abnormality diagnosis by making the vibration of the holding
current for a predetermined period. This prevents erroneous
determination that the fluctuation of the VTC displacement angle
occurring immediately after the holding operation start is
determined to be abnormal, and can improve accuracy and reliability
in abnormality diagnosis.
[0124] The abnormality diagnosis process explained above is
executed according to each routine in FIGS. 9 to 12 by the ECU 43.
Hereinafter, the process content of each routine will be
explained.
[Abnormality Diagnosis Routine]
[0125] An abnormality diagnosis routine in FIGS. 9 and 11 is
executed at each calculating timing of an engine rotational speed
during engine operating (for example, every 180.degree. CA in a
case of a four-cylinder engine). When the present routine is
activated, first at step 1101, a target displacement angle vvttgt
(target valve timing) in accordance with the present engine
operating condition (engine rotational speed, intake pressure or
the like) is calculated by a map or the like. After that, the
process goes to step 1102, wherein an OCV current value (control
duty dutyvvt) is feedback-controlled so that a deviation between
the present VTC displacement angle vvt and the target displacement
angle vvttgt is small.
[0126] Thereafter, the process goes to step 1103, wherein it is
determined whether or not an abnormality diagnosis executing flag
xvvtchk is set as "0" which means "not during abnormality diagnosis
executing" (during dither control executing). When the abnormality
diagnosis executing flag xvvtchk is set as "1", it is determined
that it is during abnormality diagnosis executing, and the process
goes to the determination process at step 1105.
[0127] On the other hand, when it is determined at step 1103 that
the abnormality diagnosis executing flag xvvtchk is set as "0", it
is determined that it is not during abnormality diagnosis executing
(during dither control executing), and the process goes to step
1104, wherein it is determined whether or not an absolute value
|vvttgt-vvt| of a deviation between the present target displacement
angle vvttgt and the VTC displacement angle vvt is less than a
first holding operation determination threshold value K1 (for
example, one degree or less). As a result, when it is determined
that the absolute value |vvttgt-vvt| of the deviation is greater
than the first holding operation determination threshold value K1,
it is determined that the holding operation execution condition is
not met, and the process goes to step 1106, wherein a holding
operation flag xvvtret is maintained to "0" and further, the
present target displacement angle vvttgt is stored as the target
displacement angle vvttgt 0 at holding operation start and also the
abnormality diagnosis executing flag xvvtchk is reset as "0",
proceeding to step 1121 in FIG. 10.
[0128] On the other hand, when it is determined at step 1104 that
the absolute value |vvttgt-vvt| of the deviation is less than the
first holding operation determination threshold value K1, the
process goes to step 1105, wherein it is determined whether or not
a deviation |vvttgt-vvttgt 0| between the present target
displacement angle vvttgt and the target displacement angle vvttgt
0 at holding operation start is less than a second holding
operation determination threshold value K2 (for example, two
degrees or less). As a result, when it is determined that the
absolute value |vvttgt-vvttgt 0| of the deviation is less than the
second holding operation determination threshold value K2, it is
determined that the requirement of the target displacement angle
change has occurred during holding operation executing and the
process does not go to the holding operation execution steps
subsequent to step 1107, but goes to step 1106, wherein the holding
operation flag xvvtret is maintained to "0" and further, the
present target displacement angle vvttgt is stored as the target
displacement angle vvttgt 0 at holding operation start and also the
abnormality diagnosis executing flag xvvtchk is reset as "0",
proceeding to step 1121 in FIG. 10.
[0129] When it is determined at step 1105 that a required value of
the target displacement angle has changed even after entering into
the holding operation, the holding operation and the abnormality
diagnosis process are interrupted, and a usual target displacement
angle F/B process may be executed.
[0130] In addition, when at step 1105, it is determined that the
deviation |vvttgt-vvttgt 0| between the present target displacement
angle vvttgt and the target displacement angle vvttgt 0 at holding
operation start is less than the second holding operation
determination threshold value K2, it is determined that the holding
operation execution condition is met, and the process goes to step
1107, wherein the holding operation flag xvvtret is set as "1"
which means "during holding operating". After that, the process
goes to step 1108, wherein holding operation start timing is
determined based upon whether or not the previous value of the
holding operation flag xvvtret is "0".
[0131] As a result, when it is determined that it is not the
holding operation timing, the process goes to step 1109 in FIG. 10
and when it is determined that it is the holding operation timing,
the process goes to step 1109, wherein the holding operation time
counter cvvtret is initialized to "0". This holding operation time
counter cvvtret is a time counter for counting an elapse time after
the holding operation start by a timed relation process different
from the present routine. In addition, at next step 1110, the
present target displacement angle vvttgt is stored as the target
displacement angle vvttgt 0 at holding operation start.
[0132] After that, at steps 1111 and 1112 in FIG. 10, it is
determined whether or not a predetermined abnormality diagnosis
execution condition (dither control execution condition) is met, as
follows. First at step 1111, it is determined whether or not an
elapse time after the holding operation start counted by the
holding operation time counter cvvtret is more than a predetermined
time K3 (for example, equal to 500 ms or more). This predetermined
time K3 is set to time required from a point the holding operation
start to a point the VTC displacement angle vvt corresponds to the
target displacement angle and is stably held. When at step 1111, it
is determined that the elapse time cvvtret after the holding
operation start is less than the predetermined time K3, the
abnormality diagnosis execution condition (dither control execution
condition) is to be not met.
[0133] When at step 1111, it is determined that the elapse time
cvvtret after the holding operation start is more than the
predetermined time K3, whether or not the abnormality diagnosis
execution precondition is met is determined based upon whether or
not .the following conditions (1) to (3) are all satisfied. [0134]
(1) An engine rotational speed is more than a predetermined
rotational speed. [0135] (2) An oil temperature of an engine is
more than a predetermined temperature. [0136] (3) A discharge
hydraulic pressure of the oil pump 27 is stable.
[0137] When at either one of steps 1111 and 1112, it is determined
that the determination result is "NO" (i.e., in a case where an
elapse time cvvtret after the holding operation start is less than
the predetermined time K3 or, in a case where the abnormality
diagnosis execution precondition is not met), it is determined that
the abnormality diagnosis execution condition (dither control
execution condition) is not met and the process goes to step 1116,
wherein after a dither correction duty diz [%] of the hold duty is
set as "0", the process goes to step 1117. The present VTC
displacement angle vvt is stored as a VTC displacement angle vvtret
0 at the time of no dither and at next step 1118, the abnormality
diagnosis executing flag xvvtchk is reset as "0", proceeding to
step 1119.
[0138] On the other hand, when at both of steps 1111 and 1112, the
determination result is "Yes" (i.e., in a case where an elapse time
cvvtret after the holding operation start is more than the
predetermined time K3 or, in a case where the abnormality diagnosis
execution precondition is met), it is determined that the
abnormality diagnosis execution condition (dither control execution
condition) is met and the process goes to step 1113, wherein by
referring to an increasing direction amplitude map in FIG. 13, an
increasing direction amplitude dizp [%] of the hold duty is
calculated in accordance with the present engine rotational speed
ne and by referring to a decreasing direction amplitude map in FIG.
14, a decreasing direction amplitude dizm [%] of dither in the hold
duty is calculated in accordance with the present engine rotational
speed ne.
[0139] An amplitude map in each of both directions of the dither in
FIGS. 13 and 14 is made in such a manner that as the engine
rotational speed ne is higher (as the discharge hydraulic pressure
of the oil pump 27 is higher), amplitudes dizp and dizm in both
directions of the dither increase in stages. However, the present
invention may be adapted such that amplitudes dizp and dizm in both
directions of the dither are constant regardless of an engine
rotational speed ne.
[0140] In addition, considering the characteristic that the
hydraulic pressure in the advance hydraulic chamber 18 easier leaks
than the hydraulic pressure in the retard hydraulic chamber 19 due
to the structure of the vane-type variable valve timing controller
11, an increasing direction amplitude dizp (advance direction
amplitude) of the dither of the hold duty is set to be slightly
greater than a decreasing direction amplitude dizm thereof (retard
direction amplitude). Thereby, a VTC displacement angle changing
amount by the increasing direction amplitude dizp of the dither
(advance direction amplitude) of the hold duty is designed to be
substantially the same as the decreasing direction amplitude dizm
thereof (retard direction amplitude). However, the present
invention may be adapted such that the increasing direction
amplitude dizp (advance direction amplitude) of the dither of the
hold duty is equal to the decreasing direction amplitude dizm
thereof (retard direction amplitude).
[0141] Thereafter, the process goes to step 1114, wherein the
abnormality diagnosis executing flag xvvtchk is set as "1".
Thereafter, the process goes to step 1115, wherein a dither
correction duty [%] to the hold duty drets is calculated by
executing a dither correction duty calculation routine in FIG. 12
to be described later.
[0142] After that, the process goes to step 1119, wherein the hold
duty drets (holding current) in advance learned is read out. In
regard to the learning of the hold duty drets, if a certain hold
duty learning condition is met for each execution of the holding
operation, a learning value of the hold duty drets may be updated
or a learning frequency of the hold duty drets is smaller for the
each time. Further, the hold duty drets may be learned in each
region of the target displacement angle vvttgt (or each engine
operating condition) or a single hold duty drets which is common in
all target displacement angles vvttgt (or all engine operating
conditions) may be learned. The hold duty drers thus learned is
stored in a writable, involatile memory such as a backup RAM of the
ECU 43. In addition, at next step 1120 the dither correction duty
diz is added to the hold duty drets to obtain a control duty
dutyvvt. dutyvvt=drets+diz.
[0143] Thereafter, the process goes to step 1121, wherein the
control duty dutyvvt is outputted to the hydraulic control valve
21. Thereby, the dither is applied to the control duty dutyvvt by
the dither correction duty diz during the dither control period of
the control duty dutyvvt.
[0144] After that, the process goes to step 1122, wherein it is
determined whether or not the VTC displacement control is during
holding operating based upon whether or not the holding operation
flag xvvtret is set as "1". When the valve timing control is not
during holding operating, the present routine ends as it is.
[0145] On the other hand, when at step 1122 it is determined that
the VTC displacement control is during holding operating
(xvvtret=1), the process goes to step 1123, wherein it is
determined whether or not the VTC displacement control is during
abnormality diagnosis executing (dither control executing), based
upon whether or not the abnormality diagnosis executing flag
xvvtchk is set as "1". When the VTC displacement control is not
during abnormality diagnosis executing, the present routine ends as
it is.
[0146] In addition, when at step 1123, wherein it is determined
that the VTC displacement control is during abnormality diagnosis
executing (xvvtchk=1), the process goes to step 1124, wherein it is
determined whether or not an elapse time counted by the holding
operation time counter cvvtret after the holding operation start is
more than a predetermined time K4 (for example, 2000 ms or more).
This predetermined time K4 is time required from the holding
operation start to termination of the abnormality diagnosis (dither
control). When at step 1124, it is determined that the elapse time
cvvtret counted by the holding operation time counter after the
holding operation start is less than the predetermined time K4, it
is determined that the VTC displacement control is during
abnormality diagnosis executing and the present routine ends as it
is.
[0147] After that, at a point where the elapse time cvvtret counted
by the holding operation time counter after the holding operation
start reaches the predetermined time K4, at step 1124 the
determination result is "Yes", the process goes to step 1125,
wherein a deviation between a VTC displacement angle vvtret 0
without the dither (immediately before the dither control start)
and the present VTC displacement angle vvt (at the abnormality
diagnosis termination) is calculated as an abnormality diagnosis
deviation dvvtdg. dvvtdg=vvtret 0-vvt.
[0148] Thereafter, the process goes to step 1126, wherein it is
determined whether or not an engine rotational speed is in a region
of a low rotational side, based upon the present engine rotational
speed is less than a predetermined value ne1 (for example, 1800 rpm
or less). In this region the drain switching valves 34 and 35 are
securely closed if the drain switching valve 34 and 35 are normal
during holding operating. When the engine rotational speed is in
this region of the low rotational side (engine rotational
speed.ltoreq.ne1), by steps 1128 to 1134, "open abnormality
determination process" where presence/absence of open abnormality
state in the drain switching valves 34 and 35 and/or the one-way
valves 30 and 31 is determined is executed as follows
[0149] First, at step 1128 the abnormality diagnosis deviation
dvvtdg is compared with a determination threshold value K5 (for
example, +5.degree. CA) of the open abnormality in the side of the
advance hydraulic chamber 18. When it is determined that the
abnormality diagnosis deviation dvvtdg is more than the
determination threshold value K5 of the open abnormality in the
side of the advance hydraulic chamber 18 (that is, a changing
amount in the retard side of the VTC displacement angle during
abnormality diagnosis period is more than the determination
threshold value K5), it is determined that the open abnormality
occurs in the drain switching valve 34 and/or the one-way valve 30
in the side of the advance hydraulic chamber 18, the process goes
to step 1129, wherein the abnormality flag in the side of the
advance hydraulic chamber xladvfail is set as "1" which means that
there occurs the open abnormality. On the other hand, When it is
determined that the abnormality diagnosis deviation dvvtdg is less
than the determination threshold value K5 of the open abnormality
in the side of the advance hydraulic chamber 18 (that is, a
changing amount in the retard side of the VTC displacement angle
during abnormality diagnosis period is less than the determination
threshold value K5), it is determined that the open abnormality
does not occur in the drain switching valve 34 and/or the one-way
valve 30 in the side of the advance hydraulic chamber 18, and the
process goes to step 1130, wherein the abnormality flag in the side
of the advance hydraulic chamber xladvfail is set as "0" which
means no occurrence of the open abnormality (normal).
[0150] Thereafter, the process goes to step 1131, wherein the
abnormality diagnosis deviation dvvtdg is compared with a
determination threshold value K6 (for example, -5.degree. CA) of
the open abnormality in the side of the retard hydraulic chamber
19. When it is determined that the abnormality diagnosis deviation
dvvtdg is less than the determination threshold value K6 of the
open abnormality in the side of the retard hydraulic chamber 19
(that is, a changing amount in the advance side of the VTC
displacement angle during abnormality diagnosis period is more than
an absolute value of the determination threshold value K6), it is
determined that the open abnormality occurs in the drain switching
valve 35 and/or the one-way valve 31 in the side of the retard
hydraulic chamber 19, and the process goes to step 1132, wherein
the abnormality flag in the side of the retard hydraulic chamber
xlretfail is set as "1" which means that there occurs the open
abnormality. On the other hand, When it is determined that the
abnormality diagnosis deviation dvvtdg is more than the
determination threshold value K6 of the open abnormality in the
side of the retard hydraulic chamber 19 (that is, a changing amount
in the advance side of the VTC displacement angle during
abnormality diagnosis period is smaller than the absolute value of
the determination threshold value K6), it is determined that the
open abnormality does not occur in the drain switching valve 35
and/or the one-way valve 31 in the side of the retard hydraulic
chamber 19, and the process goes to step 1133, wherein the
abnormality flag in the side of the retard hydraulic chamber
xlretfail is set as "0" which means no occurrence of the open
abnormality (normal).
[0151] Thereafter, the process goes to step 1134, wherein an open
abnormality determination process end flag xldiagend is set as "1"
which means the open abnormality determination process end and the
present routine ends. The open abnormality determination process
end flag xldiagend is cleared to "0" by an initialization process
at power supply to the ECU 43 and thereafter, is used for
determining whether or not the aforementioned open abnormality
determination process is executed during the subsequent engine
operating.
[0152] On the other hand, when it is determined at step 1126 that
the present engine rotational speed is not in a region of the low
rotational side (engine rotational speed.ltoreq.ne1), the process
goes to step 1127, wherein it is determined whether or not the
engine rotational speed is in a region of a high rotational side
where the drain switching valves 34 and 35 are forcibly opened by a
rotational centrifugal force during holding operating if they are
normal to create the state where the one-way valves 30 and 31 at
both the sides do not function, based upon whether or not the
present rotational speed is more than a predetermined value ne2
(for example, 1800 rpm or more). When the present engine rotational
speed is not in a region of the high rotational side, either, that
is, when the present engine rotational speed is in an intermediate
region between the determination threshold value ne1 in a region of
the low rotational side and the determination threshold value ne2
in a region of the high rotational side, since it is not clear
whether or not the drain switching valves 34 and 35 are forcibly
opened by the rotational centrifugal force, the abnormality
diagnosis process is not executed at all and the present routine
ends as it is.
[0153] In contrast, when at step 1127, the present rotational speed
is more than the predetermined value ne2, it is determined that the
engine rotational speed is in a region of the high rotational side
where the drain switching valves 34 and 35 are forcibly opened by a
rotational centrifugal force during holding operating if they are
normal to create the state where the one-way valves 30 and 31 at
both the sides do not function. In consequence, by steps 1135 to
1141, "closed abnormality determination process" where
presence/absence of the closed abnormality state in the drain
switching valves 34 and 35 is determined is executed as
follows.
[0154] First, at step 1128 the abnormality diagnosis deviation
dvvtdg is compared with a determination threshold value K7 (for
example, +5.degree. CA) of the closed abnormality in the side of
the retard hydraulic chamber 19. When it is determined that the
abnormality diagnosis deviation dvvtdg is more than the
determination threshold value K7 of the closed abnormality in the
side of the retard hydraulic chamber 19 (that is, a changing amount
in the retard side of the VTC displacement angle during abnormality
diagnosis period is more than the determination threshold value
K7), it is determined that the closed abnormality occurs in the
drain switching valve 35 in the side of the retard hydraulic
chamber 19, and the process goes to step 1136, wherein the closed
abnormality flag in the side of the retard hydraulic chamber
x2retfail is set as "1" which means that there occurs the closed
abnormality. On the other hand, When it is determined that the
abnormality diagnosis deviation dvvtdg is less than the
determination threshold value K7 of the closed abnormality in the
side of the retard hydraulic chamber 19 (that is, a changing amount
in the retard side of the VTC displacement angle during abnormality
diagnosis period is less than the determination threshold value
K7), it is determined that the closed abnormality does not occur in
the drain switching valve 35 in the side of the retard hydraulic
chamber 19, and the process goes to step 1137, wherein the closed
abnormality flag in the side of the retard hydraulic chamber
x2retfail is set as "0" which means no occurrence of the closed
abnormality (normal).
[0155] Thereafter, the process goes to step 1138, wherein the
abnormality diagnosis deviation dvvtdg is compared with a
determination threshold value K8 (for example, -5.degree. CA) of
the closed abnormality in the side of the advance hydraulic chamber
18. When it is determined that the abnormality diagnosis deviation
dvvtdg is less than the determination threshold value K8 of the
closed abnormality in the side of the advance hydraulic chamber 18
(that is, a changing amount in the advance side of the VTC
displacement angle during abnormality diagnosis period is more than
an absolute value of the determination threshold value K8), it is
determined that the closed abnormality occurs in the drain
switching valve 34 in the side of the advance hydraulic chamber 18,
and the process goes to step 1139, wherein the closed abnormality
flag in the side of the advance hydraulic chamber x2advfail is set
as "1" which means that there occurs the closed abnormality. On the
other hand, When it is determined that the abnormality diagnosis
deviation dvvtdg is more than the determination threshold value K8
of the closed abnormality in the side of the advance hydraulic
chamber 18 (that is, a changing amount in the advance side of the
VTC displacement angle during abnormality diagnosis period is
smaller than the absolute value of the determination threshold
value K8), it is determined that the closed abnormality does not
occur in the drain switching valve 34 in the side of the advance
hydraulic chamber 18, and the process goes to step 1140, wherein
the closed abnormality flag in the side of the advance hydraulic
chamber x2advfail is set as "0" which means no occurrence of the
closed abnormality (normal).
[0156] Thereafter, the process goes to step 1141, wherein a closed
abnormality determination process end flag x2ldiagend is set as "1"
which means the closed abnormality determination process end and
the present routine ends. The closed abnormality determination
process end flag x2diagend is cleared to "0" by an initialization
process at power supply to the ECU 43 and thereafter, is used for
determining whether or not the aforementioned closed abnormality
determination process is executed during the subsequent engine
operating.
[0157] [Dither Correction Duty Calculation Routine]
[0158] A dither correction duty calculation routine in FIG. 12 is a
subroutine executed at step 1115 in FIG. 10. However, the present
routine is executed for each predetermined time (for example, each
of 2 ms).
[0159] When the present routine is activated, first at step 1201 it
is determined whether or not the previous diz is "0", that is, this
process is a cycle for executing calculation of diz for the first
time. When at step 1201 it is determined that the previous diz is
"0", the process goes to step 1202, wherein an amplitude direction
switching counter cdiz for counting an elapse time after having
switched an amplitude direction of a dither is initialized to "0".
At next step 1203, an increasing direction amplitude dizp (advance
direction amplitude) calculated at step 1113 in FIG. 10 is set as a
dither correction duty and further, an amplitude direction
determination flag xdiz is set as "0" which means the increasing
direction amplitude, proceeding to step 1204.
[0160] On the other hand, when at step 1201 it is determined that
the previous diz is not "0", the steps 1202 and 1203 are skipped
and the process goes to step 1204. At step 1204, the amplitude
direction switching counter cdiz is made by counting up the
previous value cdiz [I-1] by "1". cdiz=cdiz[I-1]+1.
[0161] After that, the process goes to step 1205, wherein by
referring to an amplitude direction switching time map in FIG. 15,
an amplitude direction switching time tmdiz is calculated in
accordance with the present engine rotational speed ne. This
amplitude direction switching time tmdiz is time required for
switching the amplitude direction and corresponds to 1/2 of the
dither cycle. The amplitude direction switching time map in FIG. 15
is set in a manner that, considering that as an engine rotational
speed ne is higher, a discharge hydraulic pressure of the oil pump
27 is higher, as the engine rotational speed ne is higher, the
amplitude direction switching time tmdiz is shorter by stages.
However, the present invention may set the amplitude direction
switching time tmdiz to be constant regardless of an engine
rotational speed ne.
[0162] In addition, in the amplitude direction switching time map
in FIG. 15, an amplitude direction switching time tmdiz (dither
cycle/2) in each of the present engine rotational speed ne is set
close to the minimum time in which the hydraulic pressure can be
transmitted to each hydraulic chamber 18 and 19 in the increasing
direction amplitude and the decreasing direction amplitude of the
holding current in consideration of a delay of a hydraulic
transmission system to the hydraulic chambers 18 and 19
respectively. In this way, the VTC displacement angle changing
amount at a normal operation state is reduced and at the same time,
the VTC displacement angle changing amount at an abnormal operation
state is increased. In consequence, a difference in VTC
displacement angle changing amount between at a normal operation
state and at an abnormal operation state is clarified, making it
possible to easily detect the abnormality.
[0163] Thereafter, the process goes to step 1206, wherein it is
determined whether or not the time counted in the amplitude
direction switching counter cdiz reaches more than the amplitude
direction switching time tmdiz calculated at step 1205. When the
time counted in the amplitude direction switching counter cdiz does
not reach the amplitude direction switching time tmdiz yet, the
present routine ends as it is.
[0164] After that, at a point when the time counted in the
amplitude direction switching counter cdiz has reached the
amplitude direction switching time tmdiz calculated at step 1205,
the process goes to step 1207, wherein it is determined whether or
not the amplitude direction determination flag xdiz is set as "1"
which means the decreasing direction amplitude. Since at the dither
starting, at step 1203 the amplitude direction determination flag
xdiz is set as "0" which means the increasing direction amplitude,
it is determined at step 1207 that the determination result is
"No". Therefore, the process goes to step 1209, wherein a
decreasing direction amplitude dizm (retard direction amplitude)
calculated at step 1113 in FIG. 10 is set as a dither correction
duty diz and further, and an amplitude direction determination flag
xdiz is set as "1" which means the decreasing direction amplitude.
At next step 1210, 04 the amplitude direction switching counter
cdiz is initialized to "0" and the present routine ends. Thereby,
the amplitude direction of the dither is reversed from increasing
direction to decreasing direction.
[0165] After that, at a point when the time counted in the
amplitude direction switching counter cdiz has reached the
amplitude direction switching time tmdiz calculated at step 1205,
at step 1207 the determination result is "Yes", and the process
goes to step 1208, wherein an increasing direction amplitude dizp
(advance direction amplitude) calculated at step 1113 in FIG. 10 is
set as a dither correction duty diz and further, an amplitude
direction determination flag xdiz is set as "0" which means the
increasing direction amplitude. At next step 1210, the amplitude
direction switching counter cdiz is initialized to "0" and the
present routine ends. Thereby, the amplitude direction of the
dither is reversed from decreasing direction to increasing
direction.
[0166] By repetition of the aforementioned processes, the amplitude
direction of the dither is reversed each time the time counted in
the amplitude direction switching counter cdiz reaches the
amplitude direction switching time tmdiz.
[0167] One example of the abnormality diagnosis in the present
embodiment described above is shown in a time chart of FIG. 8. In
the example of FIG. 8, at time t1 a target displacement angle
vvttgt changes in the advance direction and according to it, a VTC
displacement angle vvt is feedback-controlled in such a manner as
to change in the advance direction. In consequence, at time t2 when
an absolute value of a deviation between the target displacement
angle vvttgt and the VTC displacement angle vvt is less than a
predetermined value and a predetermined holding operation execution
condition is met, the holding operation starts. The period from
this holding operation start until the elapse of the predetermined
time K3 is determined to be a period required for the VTC
displacement angle vvt to correspond to the target displacement
angle vvttgt for stable holding, and the control duty dutyvvt is
set only to a learning value of the hold duty drets and the dither
is not applied to the control duty dutyvvt.
[0168] Thereafter, at time t3 when the predetermined time K3 has
elapsed from the holding operation start, the abnormality diagnosis
condition (dither control execution condition) is met to start the
dither control. During this dither controlling, the increasing
direction amplitude dizp (advance direction amplitude) and the
decreasing direction amplitude dizm (retard direction amplitude)
are alternately added to the hold duty (learning value) of the
hydraulic control valve 21 for each amplitude direction switching
time tmdiz. Thereby, the control duty of the hydraulic control
valve 21 is alternately switched in the amplitude direction of the
dither centered at the hold duty drets for each amplitude direction
switching time tmdiz to perform the dither control of the
amplitudes dizp and dizm.
[0169] In an example in FIG. 8, a chain line shows a behavior of a
VTC displacement angle vvt when the open abnormality state occurs
where the drain switching valve 34 and/or the one-way valve 30 in
the side of the advance hydraulic chamber 18 remain to be
opened.
[0170] In a case of performing the holding operation at a region of
the low rotation side, when both of the drain switching valves 34
and 35 at the side of the advance hydraulic chamber 18 and at the
side of the retard hydraulic chamber 19 operate normally, both of
the drain switching valves 34 and 35 close. Therefore, when both of
the one-way valves 30 and 31 are normal, the reverse flow
prevention function of both of the one-way valves 30 and 31 can be
effectively achieved. Therefore, even when the dither is applied to
the hold duty drets, the VTC displacement angle vvt is held close
to the target displacement angle vvttgt. However, when the drain
switching valve 34 and/or the one-way valve 30 at the side of the
advance hydraulic chamber 18 is in an open abnormality state, the
hydraulic pressure in the advance hydraulic chamber 18 where the
open abnormality state is occurring is leaked through the drain
switching valve 34 or the one-way valve 30 and is reduced.
Therefore, the hydraulic pressure in the retard hydraulic chamber
19 is greater than the hydraulic pressure in the advance hydraulic
chamber 18, creating the phenomenon that the VTC displacement angle
displaces in the retard direction.
[0171] At time t4 when the dither control is executed for a
predetermined time (at time t4 when a predetermined time K4 elapses
from the holding operation start), the dither control is terminated
to return the control duty dutyvvt of the hydraulic control valve
21 to the hold duty drets only, and further, a deviation between a
VTC displacement angle vvtret 0 without dither (immediately before
the dither control start) and a VTC displacement angle vvt at time
t4 of dither control termination (at abnormality diagnosis
termination) is calculated as an abnormality diagnosis deviation
dvvtdg. In addition, the abnormality diagnosis deviation dvvtdg is
compared with a determination threshold value K5 (for example,
+5.degree. CA) of the open abnormality in the side of the advance
hydraulic chamber 18. Based upon whether or not the abnormality
diagnosis deviation dvvtdg is more than the determination threshold
value K5 of the open abnormality in the side of the advance
hydraulic chamber 18 (a changing amount in the retard side of the
VTC displacement angle during abnormality diagnosis period is more
than the determination threshold value K5), it is determined
whether or not the open abnormality occurs in the drain switching
valve 34 and/or the one-way valve 30 in the side of the advance
hydraulic chamber 18.
[0172] In a behavior of the VTC displacement angle shown in one
chain line of FIG. 8, when the abnormality diagnosis deviation
dvvtdg is more than the determination threshold value K5 as the
open abnormality in the side of the advance hydraulic chamber 18,
the open abnormality in the side of the advance hydraulic chamber
18 is determined, setting the open abnormality flag xladvfail in
the side of the advance hydraulic chamber to "1" which means that
there occurs the open abnormality.
[0173] According to the present embodiment described above, since
the control duty in the hydraulic control chamber 21 dutyvvt is
vibrated during hold operating, the determination can be made as to
presence/absence of abnormality in the drain switching valves 34
and 35 and/or the one-way valves 30 and 31, based upon whether or
not the changing degree of the VTC displacement angle vvt due to
vibration of the control duty dutyvvt is great. As a result, the
abnormality in the drain switching valves 34 and 35 or the one-way
valves 30 and 31 can be quickly detected.
[0174] It should be noted that according to the abnormality
diagnosis system of the present embodiment, when both the drain
switching valves 34 and 35 (or one-way valves 30 and 31) in the
side of the advance hydraulic chamber 18 and the side of the retard
hydraulic chamber 19 are simultaneously in an open abnormality
state, it may be hard to detect the abnormality, but probability
that both the drain switching valves 34 and 35 (or one-way valves
30 and 31) are simultaneously abnormal is extremely small as
compared to the probability that either one of the drain switching
valves (or one-way valves) is abnormal, and therefore, the
abnormality in most cases can be quickly detected by the
abnormality diagnosis method of the present embodiment.
[0175] In addition in the present invention, a hydraulic switching
valve for switching the hydraulic pressure driving the drain
switching valves 34 and 35 may be separated from the hydraulic
control valve 21, but the present embodiment is so structured that
the hydraulic switching valve is integral with the hydraulic
control valve 21, and therefore, has an advantage of being capable
of meeting the requirements such as reduction in the number of
component parts, reduction in costs and downsizing.
[0176] Further, the present embodiment detects the abnormality by
using the following method, considering that in a region of a
high-rotation side where an engine rotational speed is more than a
predetermined value, the drain switching valves 34 and 35
respectively are forcibly opened due to the rotational centrifugal
force all the time regardless of the control hydraulic pressure in
the drain switching valves 34 and 35 respectively, creating the
state where the functions of the respective one-way valves 30 and
31 do not work. That is, in a case of performing the holding
operation in a region of a low rotational side, the control duty in
the hydraulic control chamber 21 dutyvvt is vibrated to determine
presence/absence of the open abnormality states in the drain
switching valves 34 and 35 and/or the one-way valves 30 and 31 and
also in a case of performing the holding operation in a region of a
high rotational side, the control duty in the hydraulic control
chamber 21 dutyvvt is vibrated to determine presence/absence of the
closed abnormality states in the drain switching valves 34 and 35.
As a result, both of "open abnormality" and "closed abnormality"
can be quickly detected.
[0177] However, the present invention may be structured such that
in a region of a high rotational side, respective drain switching
valves 34 and 35 are not opened by a rotational centrifugal
force.
Embodiment 3
[0178] In Embodiment 3, the open abnormality will be detected as
follows.
[0179] When both of the drain switching valves 34 and 35 in the
side of the advance hydraulic chamber 18 and in the side of the
retard hydraulic chamber 19 operate normally during holding
operating, both of the drain switching valves 34 and 35 close.
Therefore, when both of the one-way valves 30 and 31 are normal, a
reverse flow prevention function of each of the one-way valves 30
and 31 can be made to effectively operate. However, when there
occurs the open abnormality state where either one of the drain
switching valves 34 and 35 (or the one-way valves 30 and 31)
remains to be opened, either one of the drain switching valves 34
and 35 (or the one-way valves 30 and 31) is fixed in a state of
being opened even during the holding operating. Accordingly, when
either one of the drain switching valves 34 and 35 (or the one-way
valves 30 and 31) is in an open abnormality state, the hydraulic
pressures in the hydraulic chambers 18 and 19 in the side where the
open abnormality occurs are leaked through the drain switching
valves 34 and 35 (or the one-way valves 30 and 31) and reduced. In
consequence, the balance in hydraulic pressure between the
hydraulic chambers 18 and 19 is off, being unable of maintaining
the VTC displacement angle at a constant position, so that there
occurs the phenomenon where a changing amount of the VTC
displacement angle increases.
[0180] Considering this characteristic, Embodiment 3 is adapted to
determine whether or not the drain switching valves 34 and 35
and/or the one-way valves 30 and 31 are in an open abnormality
state based upon whether or not a changing amount of the VTC
displacement angle within a predetermined period exceeds a normal
range during holding operating.
[0181] In this case, there are considered various methods of
detecting a changing amount of the VTC displacement angle within a
predetermined period during holding operating. For example, the
following methods are considered.
[0182] [Method (1) of Detecting a Changing Amount of the VTC
Displacement Angle During Holding Operating]
[0183] A difference between a VTC displacement angle immediately
after start of the holding operation and a VTC displacement angle
at elapse of a predetermined period is calculated and the
determination is made as to presence/absence of open abnormality
states of the drain switching valves 34 and 35 and/or the one-way
valves 30 and 31 based upon this difference. In this way, a case
where the VTC displacement angle at the elapse of a predetermined
period displaces largely in the retard direction relative to the
VTC displacement angle immediately after the start of the holding
operation and a case where it displaces excessively in the advance
direction are distinguished and determined, so that it can be
determined which side of the advance hydraulic chamber 18 and the
retard hydraulic chamber 19 the open abnormality states of the
drain switching valves 34 and 35 (or the one-way valves 30 and 31)
have occurred in, being capable of identifying the occurrence
location of the open abnormality state.
[0184] For example, as shown in a chain line of FIG. 16, when the
VTC displacement angle during holding operating displaces
excessively in the retard direction, it can be determined that the
drain switching valve 34 (or the one-way valve 30) in the side of
the advance hydraulic chamber 18 for effecting the hydraulic
pressure in the advance direction relative to the vane 17 is in an
open abnormality state and the hydraulic pressure in the advance
hydraulic chamber 18 is leaked through the drain switching valve 34
(or the one-way valve 30) and reduced. In addition, when the VTC
displacement angle during holding operating displaces excessively
in the advance direction, it can be determined that the drain
switching valve 35 (or the one-way valve 31) in the side of the
retard hydraulic chamber 19 for effecting the hydraulic pressure in
the retard direction relative to the vane 17 is in an open
abnormality state and the hydraulic pressure in the retard
hydraulic chamber 19 is leaked through the drain switching valve 35
(or the one-way valve 31) and reduced.
[0185] [Method (2) of Detecting a Changing Amount of the VTC
Displacement Angle During Holding Operating]
[0186] In a case where both of the drain switching valves 34 and 35
in the side of the advance hydraulic chamber 18 and in the side of
the retard hydraulic chamber 19 are in an open abnormality, since
during holding operating (particularly during holding operating in
a low rotational region where the supply hydraulic pressure from
the oil pump 27 is low), return of the VTC displacement angle due
to friction torque of the cam shaft occurs in a timed relation to
rotation of the cam shaft, there occurs the phenomenon that the VTC
displacement angle vibrates relatively largely cantered at a target
displacement angle alternately in the advance direction and in the
retard direction in a timed relation to rotation of the cam shaft
as shown in FIG. 17.
[0187] Considering this characteristic, Embodiment 3 detects the
maximum value and the minimum value of the VTC displacement angle
from a point immediately after start of the holding operation to a
point at elapse of a predetermined period and calculates a
difference therebetween, determining presence/absence of open
abnormality states of the drain switching valves 34 and 35 and/or
the one-way valves 30 and 31 based upon this difference. In this
case, the maximum margin in the vibration range of the VTC
displacement angle is found from the difference between the maximum
value and the minimum value of the VTC displacement angle.
Accordingly when the difference between the maximum value and the
minimum value of the VTC displacement angle (the maximum margin of
the vibration range) exceeds a normal range, it can be determined
that the drain switching valve 34 and 35 and/or the one-way valves
30 and 31 in the side of the advance hydraulic chamber 18 and the
side of the retard hydraulic chamber 19 are in an open abnormality
state.
[0188] [Method (3) of Detecting a Changing Amount of the VTC
Displacement Angle Period During Holding Operating]
[0189] Embodiment 3 detects the maximum value and the minimum value
of the VTC displacement angle from a point immediately after start
of the holding operation to a point at elapse of a predetermined
period and calculates a deviation between a target displacement
angle during holding operating and the maximum value and a
deviation between the target displacement angle and the minimum
value, determining presence/absence of open abnormality states of
the drain switching valves 34 and 35 and/or the one-way valves 30
and 31 based upon these two deviations. In consequence, when a
changing amount (deviation) in the advance direction of the VTC
displacement angle and a changing amount (deviation) in the retard
direction of the VTC displacement angle are compared by using a
target displacement angle as reference and the changing amounts
(deviations) in both directions are substantially equal, it can be
determined that the drain switching valve 34 and 35 and/or the
one-way valves 30 and 31 in the side of the advance hydraulic
chamber 18 and the side of the retard hydraulic chamber 19 are in
an open abnormality state. On the other hand, in a case where the
changing amount (deviation) in the one side only is excessively
large, it can be determined that the drain switching valve 34 and
35 (or the one-way valves 30 and 31) in the one side only are in an
open abnormality state. Accordingly, the open abnormality states in
both of the side of the advance hydraulic chamber 18 and the side
of the retard hydraulic chamber 19 and the open abnormality state
in the one side only can be distinguished and determined.
[0190] In the following description, for convenient explanation, a
combination of "one-way valve" and "drain switching valve" is
described in "one-way valve mechanism" and "open abnormality
(state) of one-way valve and/or drain switching valve" is described
in "open abnormality (state) of one-way valve mechanism".
[0191] Embodiment 3 executes an abnormality diagnosis routine of
each in FIGS. 18 to 20 by the ECU 43 and determines a changing
amount of the VTC displacement angle within a predetermined period
during holding operating by combining three methods (1) to (3) of
detecting a changing amount of the VTC displacement angle,
determining presence/absence of open abnormality states in the
drain switching valves 34 and 35 and/or the one-way valves 30 and
31 as follows.
[0192] An abnormality diagnosis routine in FIGS. 18 and 20 is
executed at each calculating timing of an engine rotational speed
during engine operating (for example, every 180.degree. CA in a
case of a four-cylinder engine). When the present routine is
activated, first at step 2101 a target displacement angle vvttgt
(target valve timing) in accordance with the present engine
operating condition (engine rotational speed, intake pressure or
the like) is calculated by a map or the like. After that, the
process goes to step 2102, wherein an OCV current value (control
duty dutyvvt) is feedback-controlled so that a deviation between
the present VTC displacement angle vvt and the target displacement
angle vvttgt becomes small.
[0193] Thereafter, the process goes to step 2103, wherein it is
determined whether or not an abnormality diagnosis executing flag
xvvtchk is cleared to "0" which means "not during abnormality
diagnosis executing". When the abnormality diagnosis executing flag
xvvtchk is set as "1", it is determined that it is during
abnormality diagnosis executing, the process goes to the
determination process at step 2105.
[0194] On the other hand, when it is determined at step 2103 that
the abnormality diagnosis executing flag xvvtchk is cleared to "0",
it is determined that it is not during abnormality diagnosis
executing, and the process goes to step 2104, wherein it is
determined whether or not an absolute value |vvttgt-vvt| of a
deviation between the present target displacement angle vvttgt and
the VTC displacement angle vvt is less than a holding operation
determination threshold value K1 (for example, one degree or less).
As a result, when it is determined that the absolute value
|vvttgt-vvt| of the deviation is greater than the holding operation
determination threshold value K1, it is determined that the holding
operation execution condition is not met, and the process goes to
step 2106, wherein the abnormality operation executing flag xvvtchk
is cleared to "0", proceeding to step 2117 in FIG. 19.
[0195] On the other hand, when it is determined at step 2104 that
the absolute value |vvttgt-vvt| of the deviation is less than the
holding operation determination threshold value K1, the process
goes to step 2105, wherein whether or not the abnormality diagnosis
execution condition is met is determined based upon whether or not
.the following conditions (1) to (3) are all satisfied, for
example. [0196] (1) An engine rotational speed is more than a
predetermined rotational speed. [0197] (2) An oil temperature of an
engine (cooling water temperature) is more than a predetermined
temperature. [0198] (3) A discharge hydraulic pressure of the oil
pump 27 is more than a predetermined value.
[0199] When any one of these three conditions (1) to (3) is not
satisfied, it results in that the abnormality diagnosis execution
condition is not met and the process goes to step 2106, wherein the
abnormality operation executing flag xvvtchk is cleared to "0",
proceeding to step 2117 in FIG. 19.
[0200] On the other hand, when these three conditions (1) to (3)
are all satisfied, it is determined that the abnormality diagnosis
execution condition is met and the process goes to step 2107,
wherein the pre-learned hold duty (holding current) is read out to
start the holding operation and at the same time, start the
abnormality diagnosis process.
[0201] It should be noted that, as for the learning of the hold
duty, when a predetermined hold duty learning condition is met, a
learning value of the hold duty may be updated for each time or the
learning frequency of the hold duty may be smaller than this.
Further, the hold duty may be learned at each region of the target
displacement angle vvttgt (or each engine operating region) and a
single hold duty which is in common among all target displacement
angles (or all engine operating regions) may be learned. Such
learned hold duty is updated and stored in a rewritable, involatile
memory such as a backup RAM in the ECU 43.
[0202] And it is determined at step 2108 whether or not the
abnormality diagnosis executing flag xvvtchk is set as "0". When
the abnormality diagnosis executing flag xvvtchk is set as "1,", it
is determined that it is during abnormality diagnosis executing,
and the process skips initialization processes at start of the
abnormality diagnosis at steps 2109 to 2112 and goes to the
determination process step 2113 in FIG. 19.
[0203] On the other hand, in a case where it is determined at step
2105 that the abnormality diagnosis execution condition is met and
also it is determined at step 2108 that the abnormality diagnosis
executing flag xvvtchk is "0", it is determined that the VTC
displacement control is at start of the abnormality diagnosis and
the initialization processes at start of the abnormality diagnosis
at steps 2109 to 2112 are executed.
[0204] At the initialization process at start of the abnormality
diagnosis, at step 2109 an abnormality diagnosis execution time
counter cvvtret is initialized to "0". This abnormality diagnosis
execution time counter cvvtret is a time counter for counting an
elapse time after starting the abnormality diagnosis (after
starting the holding operation) by a time-related process different
from the present routine. In addition, at next step 2110 the
present VTC displacement angle vvt is stored as a VTC displacement
angle vvtret 0 at start of the abnormality diagnosis (start of the
holding operation). Thereafter, the process goes to step 2111,
wherein the present VTC displacement angle wt is stored as each of
an initial value of the minimum value of the VTC displacement angle
vvtmin and an initial value of the maximum value of the VTC
displacement angle vvtmax. After that, the process goes to step
2112, wherein the abnormality diagnosis executing flag xvvtchk is
set as "1" which means "during abnormality diagnosis executing" and
the process goes to the determination process at step 2113 in FIG.
19.
[0205] In addition, at step 2113 in FIG. 19 the stored value of the
minimum value of the VTC displacement angle vvtmin and the present
VTC displacement angle vvt are compared. When the present VTC
displacement angle vvt is smaller than the stored value of the
minimum value of the VTC displacement angle vvtmin, the process
goes to step 2114, wherein the present VTC displacement angle vvt
is updated and stored as the minimum value of the VTC displacement
angle vvtmin. However, when the present VTC displacement angle vvt
is greater than the stored value of the minimum value of the VTC
displacement angle vvtmin, the stored value of the minimum value of
the VTC displacement angle vvtmin is not updated. During the
abnormality diagnosis period, the processes at steps 2113 and 2114
are repeated, thereby updating and storing the minimum value of the
VTC displacement angle vvtmin during the abnormality diagnosis
period.
[0206] Thereafter, the process goes to step 2115, wherein the
stored value of the maximum value of the VTC displacement angle
vvtmax and the present VTC displacement angle vvt are compared.
When the present VTC displacement angle vvt is greater than the
stored value of the maximum value of the VTC displacement angle
vvtmax, the process goes to step 2116, wherein the present VTC
displacement angle vvt is updated and stored as the maximum value
of the VTC displacement angle vvtmax. However, when the present VTC
displacement angle vvt is smaller than the stored value of the
maximum value of the VTC displacement angle vvtmax, the stored
value of the maximum value of the VTC displacement angle vvtmax is
not updated. During the abnormality diagnosis period, the processes
at steps 2115 and 2116 are repeated, thereby updating and storing
the maximum value of the VTC displacement angle vvtmax during the
abnormality diagnosis period.
[0207] And it is determined at next step 2117 whether or not the
abnormality diagnosis executing flag xvvtchk is set as "1". When
the abnormality diagnosis executing flag xvvtchk is not set as "1",
it is determined that it is not during abnormality diagnosis
executing, and the present routine ends as it is.
[0208] On the other hand, when it is determined at next step 2117
that the abnormality diagnosis executing flag xvvtchk is set as
"1", it is determined that it is during abnormality diagnosis
executing and the process goes to step 2118, wherein it is
determined whether or not the abnormality diagnosis execution time
(elapse time from start of the abnormality diagnosis) measured by
the abnormality diagnosis execution time counter cvvtret is more
than a predetermined time K2 (for example, 3000 ms or more). When
it does not reach the predetermined time K2, the present routine
ends as it is.
[0209] Thereafter, at a point when the measured time by the
abnormality diagnosis execution time counter cvvtret has reached
the predetermined time K2, the determination result at step 2118 is
"Yes", and the process goes to step 2119. A deviation between the
VTC displacement angle at start of the abnormality diagnosis vvtret
0 and the VTC displacement angle at the present time (at
termination of the abnormality diagnosis) is calculated and this
deviation is stored as a first abnormality diagnosis deviation
dvvtdg1. dvvtdg1=vvtret 0-vvt.
[0210] The first abnormality diagnosis deviation dvvtdg1 is an
abnormality diagnosis parameter representing how much the VTC
displacement angle vvt at termination of the abnormality diagnosis
has changed in the advance or retard direction relative to the VTC
displacement angle vvtret o at start of the abnormality diagnosis.
When the deviation is a plus value, it represents that the VTC
displacement angle vvt at termination of the abnormality diagnosis
has changed in the retard direction and when the deviation is a
minus value, it represents that the VTC displacement angle vvt at
termination of the abnormality diagnosis has changed in the advance
direction.
[0211] Thereafter, the process goes to step 2120, wherein a
deviation between the maximum value of the VTC displacement angle
vvtmax and the minimum value of the VTC displacement angle vvtmin
is calculated and this deviation is stored as a second abnormality
diagnosis deviation dvvtdg2. dvvtdg2=vvtmax-vvtmin.
[0212] The second abnormality diagnosis deviation dvvtdg2 is an
abnormality diagnosis parameter representing the maximum margin of
the vibration range of the VTC displacement angle vvt during
abnormality diagnosing.
[0213] Thereafter, at next step 2121, a deviation between the
maximum value of the VTC displacement angle vvtmax during
abnormality diagnosing and the present (during abnormality
diagnosing) target displacement angle vvttgt is calculated
(vvtmax-vvttgt) and also a deviation between the minimum value of
the VTC displacement angle vvtmin and the present (during
abnormality diagnosing) target displacement angle vvttgt is
calculated (vvtmin-vvttgt). An absolute value by addition of these
two deviations is stored as a third abnormality diagnosis deviation
dvvtdg3. dvvtdg3=|(vvtmax-vvttgt)+(vvtmin-vvttgt)|.
[0214] The third abnormality diagnosis deviation dvvtdg3 is an
abnormality diagnosis parameter representing how much the vibration
range of the VTC displacement angle vvt during abnormality
diagnosing deviates in the advance direction or in the retard
direction from the vibration range centered at the target
displacement angle vvttgt. As shown in FIG. 3, in a case where the
center of the vibration range of the VTC displacement angle vvt
during abnormality diagnosing is close to the target displacement
angle vvttgt, one deviation (vvtmax-vvttgt) becomes a plus value
and the other deviation (vvtmin-vvttgt) becomes a minus value and
also since an absolute vale of the one deviation is close to an
absolute value of the other deviation, the third abnormality
diagnosis deviation dvvtdg3 is close to "0". That is, as the third
abnormality diagnosis deviation dvvtdg3 becomes greater, the
vibration range of the VTC displacement angle vvt during
abnormality diagnosing deviates largely in the advance direction or
in the retard direction. The third abnormality diagnosis deviation
dvvtdg3 and the second abnormality diagnosis deviation dvvtdg2 are
used for distinguishing and determining the open abnormality of the
one-way valve mechanisms in both of the side of the advance
hydraulic chamber 18 and the side of the retard hydraulic chamber
19 and the open abnormality of the one-way valve mechanism in one
side only of the advance hydraulic chamber 18 and the retard
hydraulic chamber 19.
[0215] Thereafter, the process goes to step 2122 in FIG. 20,
wherein it is determined whether or not the third abnormality
diagnosis deviation dvvtdg3 is smaller than a predetermined value
K3 (for example, one degree). When it is determined that the third
abnormality diagnosis deviation dvvtdg3 is more than the
predetermined value K3, since the vibration range of the VTC
displacement angle vvt during abnormality diagnosing displaces
largely in the advance direction or in the retard direction, it is
determined that there does not occur the state where the one-way
valve mechanisms in both of the side of the advance hydraulic
chamber 18 and the side of the retard hydraulic chamber 19 are in
an open abnormality state and the process goes to step 2124. The
open abnormality flag for both one-way valve mechanisms xwopenfail
is cleared to "0".
[0216] In contrast, when it is determined at step 2122 that the
third abnormality diagnosis deviation dvvtdg3 is smaller than the
predetermined value K3, the process goes to step 2123, wherein it
is determined whether or not the second abnormality diagnosis
deviation dvvtdg2 is smaller than a predetermined value K4 (for
example, 7 degrees). As a result, when it is determined that the
second abnormality diagnosis deviation dvvtdg2 is more than the
predetermined value K4, since the maximum margin in the vibration
range of the VTC displacement angle vvt during abnormality
diagnosing exceeds a normal range, it is determined that there
occurs the state where the one-way valve mechanisms in both of the
side of the advance hydraulic chamber 18 and the side of the retard
hydraulic chamber 19 are in an open abnormality state and the
process goes to step 2125. The open abnormality flag for both the
one-way valve mechanisms xwopenfail is set as "1" and thereafter,
the process goes to step 2132, wherein an abnormality diagnosis
process end flag xdiagend is set as "1," which means an abnormality
diagnosis process termination. Then the present routine ends. The
abnormality diagnosis process end flag xdiagend is cleared to "0"
by the initialization process at power supply to the ECU 43 and is
used to determine whether or not the aforementioned open
abnormality determination process is executed during subsequent
engine operating.
[0217] On the other hand, when it is determined at step 2122 that
the third abnormality diagnosis deviation dvvtdg3 is smaller than
the predetermined value K3 and also when at step 2123 it is
determined that the second abnormality diagnosis deviation dvvtdg2
is smaller than the predetermined value K4, it is determined that
there does not occur the state where the one-way valve mechanisms
in both the sides are not in an open abnormality state and the
process goes to step 2124. The open abnormality flag for both
one-way valve mechanisms xwopenfail is cleared to "0".
[0218] In other words, only when the third abnormality diagnosis
deviation dvvtdg3 is smaller than the predetermined value K3 and
also when the second abnormality diagnosis deviation dwwtdg2 is
greater than the predetermined value K4 (that is, a case where the
VTC displacement angle vibrates centered at close to a target
displacement angle vvttgt and the maximum margin of the vibration
range exceeds a normal range), it is determined that there occurs
the state where the one-way valve mechanisms in both the sides are
in an open abnormality state and the process goes to step 2125. The
open abnormality flag for both the one-way valve mechanisms
xwopenfail is set as "1". Other than that, the open abnormality
flag for both the one-way valve mechanisms xwopenfail is cleared to
"0".
[0219] Thereafter, the process goes to step 2126, wherein it is
determined whether or not the first abnormality diagnosis deviation
dvvtdg1 is more than a predetermined value K5 (for example, 5 deg
or more). When the first abnormality diagnosis deviation dvvtdg1 is
more than the predetermined value K5, since the VTC displacement
angle vvt at a termination of the abnormality diagnosis changes
excessively largely in the advance direction relative to the VTC
displacement angle vvtret 0 at start of the abnormality diagnosis,
it is determined that the one-way valve mechanism in the side of
the advance hydraulic chamber 18 is in an open abnormality state
and the process goes to step 2127. The open abnormality flag for
the one-way valve mechanism in the side of the advance hydraulic
chamber xadvfail is set as "1". On the other hand, when the first
abnormality diagnosis deviation dvvtdg1 is less than the
predetermined value K5, the process goes to step 2128. The open
abnormality flag for the one-way valve mechanism in the side of the
advance hydraulic chamber xadvfail is cleared to "0".
[0220] Thereafter, the process goes to step 2129, wherein it is
determined whether or not the first abnormality diagnosis deviation
dvvtdg1 is less than a predetermined value K6 (for example, -5 deg
or less). When the first abnormality diagnosis deviation dvvtdg1 is
less than the predetermined value K6, since the VTC displacement
angle vvt at a termination of the abnormality diagnosis changes
excessively largely in the retard direction from the VTC
displacement angle vvtret 0 at start of the abnormality diagnosis,
it is determined that the one-way valve mechanism in the side of
the retard hydraulic chamber 19 is in an open abnormality state and
the process goes to step 2130. The open abnormality flag for the
one-way valve mechanism in the side of the retard hydraulic chamber
xretfail is set as "1". On the other hand, when the first
abnormality diagnosis deviation dvvtdg1 is greater than the
predetermined value K6, the process goes to step 2131. The open
abnormality flag for the one-way valve mechanism in the side of the
retard hydraulic chamber xretfail is cleared to "0".
[0221] Thereafter, the process goes to step 2132, wherein the
abnormality diagnosis process end flag xdiagend is set as "1" which
means the abnormality diagnosis process termination, and the
present routine ends.
[0222] An example of an abnormality diagnosis in Embodiment 3
described above is shown in each of time charts in FIGS. 16 and 17.
In the example of FIGS. 16 and 17, at time t1 a target displacement
angle vvttgt changes in the advance direction and, based upon it, a
VTC displacement angle vvt is feedback-controlled so as to change
in the advance direction. In consequence, at a point where an
absolute value of a deviation between the target displacement angle
vvttgt and the VTC displacement angle vvt is less than a
predetermined value and a predetermined holding operation execution
condition is met, the holding operation starts and at the same
time, the abnormality diagnosis process starts. During the
executing of the holding operation (abnormality diagnosis), a
control duty dutyvvt of the hydraulic control valve 21 is
maintained to the pre-learned hold duty and also the target
displacement angle vvttgt is maintained to be constant.
[0223] The example of FIG. 16 shows by a chain line a behavior of
the VTC displacement angle vvt at the time of occurrence of the
open abnormality state where the one-way valve mechanism in the
side of the advance hydraulic chamber 18 remains to be opened. When
the one-way valve mechanism in the side of the advance hydraulic
chamber 18 is in an open abnormality state, since the hydraulic
pressure in the side of the advance hydraulic chamber 18 where the
open abnormality is occurring is leaked through the one-way valve
mechanism to be reduced, the hydraulic pressure in the side of the
retard hydraulic chamber 19 is higher than the hydraulic pressure
in the side of the advance hydraulic chamber 18, creating the
phenomenon that the VTC displacement angle vvt displaces in the
retard direction.
[0224] Accordingly, in a case where the open abnormality of the
hydraulic pressure in the side of the advance hydraulic chamber 18
occurs, at time t3 of the abnormality diagnosis termination the
first abnormality diagnosis deviation dvvtdg1(=vvtret 0-vvt) as an
abnormality diagnosis parameter evaluating a changing amount in the
retard direction of the VTC displacement angle vvt during
abnormality diagnosing is more than a predetermined value K5 (for
example, 5 deg or more). As a result, it is determined that the
one-way valve mechanism in the side of the advance hydraulic
chamber 18 is in an open abnormality state and the open abnormality
flag for the one-way valve mechanism in the side of the advance
hydraulic chamber xadvfail is set as "1". In this case, since the
third abnormality deviation dvvtdg3 as an abnormality diagnosis
parameter evaluating how much the vibration range of the VTC
displacement angle during abnormality diagnosing displaces in the
advance direction or in the retard direction is more than the
predetermined value K3 (for example, 1 deg or more), it is
determined that there does not occur the state where the one-way
valve mechanisms in both of the side of the advance hydraulic
chamber 18 and the side of the retard hydraulic chamber 19 are in
an open abnormality state.
[0225] The example of FIG. 17 shows a behavior of the VTC
displacement angle vvt when the one-way valve mechanisms in the
side of the advance hydraulic chamber 18 and the side of the retard
hydraulic chamber 19 are in an open abnormality state. When the
one-way valve mechanisms in both the sides are in an open
abnormality state, since a return of the VTC displacement angle vvt
due to friction torque of the cam shaft occurs in a time relation
to rotation of the cam shaft during holding operation, there occurs
the phenomenon that the VTC displacement angle vvt relatively
largely vibrates alternately in the advance direction and in the
retard direction in a time relation to rotation of the cam shaft
during holding operation centered at the target displacement angle
vvttgt
[0226] Accordingly, in a case where the one-way valve mechanisms in
both the sides are in an open abnormality state, since the third
abnormality diagnosis deviation dvvtdg3 as the abnormality
diagnosis parameter evaluating how much the vibration range of the
VTC displacement angle during abnormality diagnosing displaces in
the advance direction or in the retard direction is smaller than
the predetermined value K3 (for example one degree) and also since
the second abnormality diagnosis deviation dvvtdg2 as an
abnormality diagnosis parameter evaluating the maximum margin of
the vibration range of the VTC displacement angle vvt during
abnormality diagnosing is more than the predetermined value K4 (for
example 7 deg or more), it is determined that there occurs the
state where the one-way valve mechanisms in both the sides are in
an open abnormality state, setting the open abnormality flag
xwopenfail for both the one-way valve mechanisms as "1".
[0227] According to Embodiment 3 described above, it is determined
whether or not the one-way valve mechanism in the side of the
advance hydraulic chamber 18 or the retard hydraulic chamber 19 is
in an open abnormality state based upon whether or not the first
abnormality diagnosis deviation dvvtdg1(=vvtret0-vvt) as the
abnormality diagnosis parameter evaluating a changing amount of the
VTC displacement angle vvt within a predetermined period after
start of the holding operation exceeds a normal range. Therefore,
an open abnormality of the one-way valve mechanism in the side of
the advance hydraulic chamber 18 or the retard hydraulic chamber 19
during engine operating can be quickly detected.
[0228] Yet, Embodiment 3 calculates a deviation (the maximum margin
of the vibration range of the VTC displacement angle vvt) between
the maximum value of the VTC displacement angle vvtmax and the
minimum value of the VTC displacement angle vvtmin during
abnormality diagnosing as a second abnormality diagnosis deviation
dvvtdg2 and further, calculates a deviation between the maximum
value of the VTC displacement angle vvtmax during abnormality
diagnosing and the target displacement angle vvttgt (vvtmax-vvttgt)
and also a deviation between the minimum value of the VTC
displacement angle vvtmin and the target displacement angle vvttgt
(vvtmin-vvttgt) and calculates an absolute value by addition of
these two deviations as a third abnormality diagnosis deviation
dvvtdg3. Since the third abnormality diagnosis deviation dvvtdg3
and the second abnormality diagnosis deviation dvvtdg2 are used as
an abnormality diagnosis parameter evaluating a changing amount and
a vibration range of the VTC displacement angle vvt during
abnormality diagnosing, the open abnormality of the one-way valve
mechanisms in both the sides and the open abnormality of the
one-way valve mechanism in one side only can be distinguished and
determined.
[0229] It should be noted that whether or not a changing amount or
a vibration range of the VTC displacement angle vvt during
abnormality diagnosing is within a normal range may be determined
by comparing a deviation between the maximum value of the VTC
displacement angle vvtmax during abnormality diagnosing and the
target displacement angle vvttgt with a predetermined value or by
comparing a deviation between the minimum value of the VTC
displacement angle vvtmin during the abnormality diagnosing and the
target displacement angle vvttgt with a predetermined value.
[0230] In addition, Embodiment 3 starts the abnormality diagnosis
process at the same time with start of the holding operation, but
may start the abnormality diagnosis process after a predetermined
time elapses from start of the holding operation.
[0231] In addition, in the present invention, a hydraulic switching
valve for switching the hydraulic pressure driving the drain
switching valves 34 and 35 may be separated from the hydraulic
control valve 21, but the present embodiment is so structured that
the hydraulic switching valve is integral with the hydraulic
control valve 21, and therefore, has an advantage of being capable
of meeting the requirements such as reduction in the number of
component parts, reduction in costs and downsizing.
Embodiment 4
[0232] When there occurs an open abnormality state where the drain
switching valves 34 and 35 remain to be closed, even in a control
region where it is required to drain oil from the hydraulic
chambers 18 and 19 (it is required to discharge the hydraulic
pressure) where the closed abnormality has occurred, the drain is
blocked by the one-way valves 30 and 31. Therefore, it is difficult
for the VTC displacement angle vvt to follow a change of the target
displacement angle vvttgt and change in good response.
[0233] Considering this characteristic, Embodiment 4 of the present
invention shown in FIGS. 21 to 23 is adapted to determine a
convergent state of the VTC displacement angle to a target
displacement angle vvttgt at a change of the target displacement
angle vvttgt and determine whether or not there occurs the state
where the drain switching valves 34 and 35 remain to be closed,
based upon the convergent state.
[0234] Embodiment 4 measures at a change of the target displacement
angle vvttgt a continuing time of the state where an absolute value
of a deviation between a target displacement angle vvttgt and a VTC
displacement angle vvt is more than a predetermined value K7 (for
example, 4 deg or more) as data representing a convergent state,
and determines whether or not the drain switching valves 34 and 35
are in a closed abnormality state, based upon whether or not this
continuing time cvvtchkc exceeds a closed abnormality determination
threshold value K8 (for example, 3000 ms). In this case, if the
state where the VTC displacement angle vvt displaces in the retard
direction relative to the target displacement angle vvttgt
continues, it is determined that the drain switching valve 35 in
the side of the retard hydraulic chamber 19 is in a closed
abnormality state (abnormality state where it is difficult to
advance due to no drain of the retard hydraulic chamber 19). If the
state where the VTC displacement angle vvt displaces in the advance
direction relative to the target displacement angle vvttgt
continues, it is determined that the drain switching valve 35 in
the side of the retard hydraulic chamber 19 is in a closed
abnormality state (abnormality state where it is difficult to
retard due to no drain of the advance hydraulic chamber 18).
[0235] The abnormality diagnosis process of Embodiment 4 described
above is executed according to the abnormality diagnosis routine in
FIGS. 21 and 22 by the ECU 43. The present routine is executed at
each calculating timing of an engine rotational speed during engine
operating (for example, every 180.degree. CA in a case of a
four-cylinder engine) and serves as abnormality diagnosis means.
When the present routine is activated, first at step 2201 a target
displacement angle vvttgt (target valve timing) in accordance with
the present engine operating condition (engine rotational speed,
intake pressure or the like) is calculated by a map or the like.
After that, the process goes to step 2202, wherein an OCV current
value (control duty dutyvvt) is feedback-controlled so that a
deviation between the present VTC displacement angle vvt and the
target displacement angle vvttgt becomes small.
[0236] Thereafter, the process goes to step 2203, wherein it is
determined whether or not the VTC displacement control is during
holding operating. When it is during holding operating, the
abnormality diagnosis execution condition is not met and the
process goes to step 2212, wherein a convergent time counter
cvvtchkc is initialized to "0" and an advance deviation detection
flag xadvjdg and a retard deviation detection flag xretjdg are
cleared to "0". Then, the present routine ends.
[0237] On the other hand, when it is determined at step 2203 that
it is not during holding operating, the process goes to step 2204,
wherein it is determined whether or not an absolute value
|vvttgt-vvt| of a deviation between the present target displacement
angle vvttgt and the VTC displacement angle vvt is greater than a
predetermined value K7 (for example, 4 deg). As a result, when it
is determined that the absolute value |vvttgt-vvt| of the deviation
is less than the predetermined K7, it is determined that the
convergent state of the VTC displacement angle vvt to the target
displacement angle vvttgt is within a normal range and the process
goes to step 2212, wherein the convergent time counter cvvtchkc is
initialized and the advance deviation detection flag xadvjdg and
the retard deviation detection flag xretjdg are cleared. Then, the
present routine ends.
[0238] On the other hand, when it is determined at step 2204 that
the absolute value |vvttgt-vvt| of the deviation is greater than
the predetermined value K7, the process goes to step 2205, wherein
whether or not the abnormality diagnosis execution condition is met
is determined based upon whether or not .the following conditions
(1) to (3) are all satisfied, for example. [0239] (1) An engine
rotational speed is more than a predetermined rotational speed.
[0240] (2) An oil temperature of an engine (cooling water
temperature) is more than a predetermined temperature. [0241] (3) A
discharge hydraulic pressure of the oil pump 27 is more than a
predetermined value.
[0242] When any one of these three conditions (1) to (3) is not
satisfied, it results in that the abnormality diagnosis execution
condition is not met and the process goes to step 2212, wherein the
convergent time counter cvvtchkc is initialized and the advance
deviation detection flag xadvjdg and the retard deviation detection
flag xretjdg are cleared. Then, the present routine ends.
[0243] On the other hand, when these three conditions (1) to (3)
are all satisfied, it is determined that the abnormality diagnosis
execution condition is met and the process goes to step 2206,
wherein it is determined whether or not a deviation (vvttgt-vvt) of
between the present target displacement angle vvttgt and the VTC
displacement angle vvt is a plus value. When the deviation
(vvttgt-vvt) is a plus value, it is determined that the present VTC
displacement angle vvt displaces in the retard direction relative
to the target displacement angle vvttgt and the process goes to
step 2207, wherein it is determined whether or not the retard
deviation detection flag xretjdg storing the deviation direction in
the retard side of the previous VTC displacement angle vvt is "0"
(that is, the deviation direction of the previous VTC displacement
angle vvt is the advance direction). As a result, when it is
determined that the retard deviation detection flag xretjdg is "0",
it is determined that the deviation direction of the VTC
displacement angle vvt is reversed from the previous advance
direction to the retard direction, and the process goes to step
2209, wherein the convergent time counter cvvtchkc is initialized
and also the retard deviation detection flag xretjdg is set as "1"
and the process goes to step 2211.
[0244] It should be noted that when the determination result at
step 2207 is "No", it is determined that the previous deviation
direction and the present deviation direction of the VTC
displacement angle vvt are the same retard direction, the process
goes to step 2211 by skipping the process of step 2209.
[0245] On the other hand, at step 2206, when it is determined that
a deviation (vvttgt-vvt) between the present target displacement
angle vvttgt and the VTC displacement angle vvt is less than "0"
(minus value), it is determined that the present VTC displacement
angle vvt displaces in the advance direction relative to the target
displacement angle vvttgt and the process goes to step 2208,
wherein it is determined whether or not the advance deviation
detection flag xadvjdg storing the deviation direction in the
advance side of the previous VTC displacement angle vvt is "0"
(that is, the deviation direction of the previous VTC displacement
angle vvt is the retard direction). As a result, when it is
determined that the advance deviation detection flag xadvjdg is
"0", it is determined that the deviation direction of the VTC
displacement angle vvt is reversed from the previous retard
direction to the advance direction, and the process goes to step
2210, wherein the convergent time counter cvvtchkc is initialized
and also the advance deviation detection flag xadvjdg is set as "1"
and the process goes to step 2211.
[0246] It should be noted that when the determination result at
step 2208 is "No", it is determined that the previous deviation
direction and the present deviation direction of the VTC
displacement angle vvt are the same advance direction, and the
process goes to step 2211 by skipping the process of step 2210. At
step 2211, it is determined whether or not the advance deviation
detection flag xadvjdg and the retard deviation detection flag
xretjdg both are "1". When the advance deviation detection flag
xadvjdg and the retard deviation detection flag xretjdg both are
"1", it is determined that the deviation of the advance direction
and the deviation of the retard direction are reversed in one
calculation cycle and the process goes to step 2212, wherein the
convergent time counter cvvtchkc is initialized and the advance
deviation detection flag xadvjdg and the retard deviation detection
flag xretjdg are cleared. Then, the present routine ends.
[0247] When at step 2211, the determination result is "No", it is
determined that the deviation direction of the VTC displacement
angle vvt is not reversed, and the process goes to step 2213 of
FIG. 23, wherein the convergent time counter cvvtchkc measures a
continuing time of the state where an absolute value of a deviation
between a target displacement angle vvttgt and a VTC displacement
angle vvt is more than a predetermined value K7 (for example, 4 deg
or more) and it is determined whether or not any of the drain
switching valves 34 and 35 is in a closed abnormality state, based
upon whether or not this measurement time exceeds a closed
abnormality determination threshold value K8 (for example, 300 ms).
This convergent time counter cvvtchkc is a time counter for
counting an elapse time after start of the abnormality diagnosis
(after measurement start of the convergent state) by a time related
process different from the present routine and is initialized by
any one of steps 2209, 2210 and 2212.
[0248] When it is determined at step 2213 that the measurement time
of the convergent time counter cvvtchkc does not reach the closed
abnormality determination threshold value K8, the present routine
ends as it is. Thereafter, at a point when the measurement time of
the convergent time counter cvvtchkc has exceeded the closed
abnormality determination threshold value K8, it is determined that
any of the drain switching valves 34 and 35 is in a closed
abnormality state, and the process goes to step 2214, wherein it is
determined whether or not the deviation direction of the VTC
displacement angle vvt is the retard direction based upon whether
or not the retard deviation detection flag xretjdg is "1". As a
result, when it is determined that the retard deviation detection
flag xretjdg is "1" (the deviation direction of the VTC
displacement angle vvt is the retard direction), it is determined
that the drain switching valve 35 in the side of the retard
hydraulic chamber 19 is in a close abnormality state (abnormality
state where it is difficult to advance due to no drain of the
hydraulic pressure in the retard hydraulic chamber 19), and the
process goes to step 2215, wherein a closed abnormality flag
xretchkf of the drain switching valve in the side of the retard
hydraulic chamber is set as "1".
[0249] On the other hand, when it is determined that the retard
deviation detection flag xretjdg is "0" (the deviation direction of
the VTC displacement angle vvt is the advance direction), it is
determined that the drain switching valve 34 in the side of the
advance hydraulic chamber 18 is in a close abnormality state
(abnormality state where it is difficult to retard due to no drain
of the hydraulic pressure in the advance hydraulic chamber 18), and
the process goes to step 2216, wherein a closed abnormality flag
xadvchkf of the drain switching valve in the side of the advance
hydraulic chamber is set as "1".
[0250] Thereafter, the process goes to step 2217, wherein it is
determined whether or not the closed abnormality flag xretchkf of
the drain switching valve in the side of the retard hydraulic
chamber and the closed abnormality flag xadvchkf of the drain
switching valve in the side of the advance hydraulic chamber both
are "1". When the determination result is "No", the present routine
ends as it is and when the determination result is "Yes", it is
determined that the drain switching valves 34 and 35 in both of the
side of the advance hydraulic chamber 18 and the side of the retard
hydraulic chamber 19 are in a closed abnormality state, and the
process goes to step 2218, wherein a closed abnormality flag
xchkvaivef of both the drain switching valves is set as "1", and
the present routine ends.
[0251] An example of the abnormality diagnosis in Embodiment 4
described above is shown in a time chart of FIG. 21. In the example
of FIG. 21, at time t1, a target displacement angle vvttgt is
changed in the advance direction and, for following this change, a
VTC displacement angle vvt is feedback-controlled so as to be
changed in the advance direction. By such change of the target
displacement angle vvttgt to the advance direction, at time t2 when
a deviation between the target displacement angle vvttgt and the
VTC displacement angle vvt is more than a predetermined value K7
(for example, 4 deg), the measurement operation of the convergent
time counter cvvtchkc starts to measure a continuing time of a
state where an absolute value of the deviation between the target
displacement angle vvttgt and the VTC displacement angle vvt is
more than the predetermined value K7.
[0252] During advance operating, the drain switching valve 35 in
the side of the retard hydraulic chamber 19 is opened to drain oil
from the retard hydraulic chamber 19, reducing the hydraulic
pressure in the retard hydraulic chamber 19 and also to fill the
oil into the advance hydraulic chamber 18, increasing the hydraulic
pressure in the advance hydraulic chamber 18. Thereby, the VTC
displacement angle vvt is controlled to be converged into the
target displacement angle vvttgt in good response. Accordingly,
when during advance operating, the drain switching valve 35 in the
side of the retard hydraulic chamber 19 is normally opened, the
continuing time of the state where then absolute value of the
deviation between the target displacement angle vvttgt and the VTC
displacement angle vvt is more than the predetermined value K7 (the
measurement time t2 to t3 of the convergent time counter cvvtchkc)
is smaller than a closed abnormality determination threshold value
K8. In consequence, the closed abnormality flag xretchkf of the
drain switching valve in the side of the retard hydraulic chamber
is maintained to "0".
[0253] In contrast, when the closed abnormality in the drain
switching valve 35 in the side of the retard hydraulic chamber 19
occurs, it is difficult to advance due to no drain of the hydraulic
pressure in the retard hydraulic chamber 19. Therefore, the
continuing time of the state where then absolute value of the
deviation between the target displacement angle vvttgt and the VTC
displacement angle vvt is more than the predetermined value K7 (the
measurement time of the convergent time counter cvvtchkc) is
longer. At time t4 when the continuing time exceeds the closed
abnormality determination threshold value K8, it is determined that
the close abnormality in the drain switching valve 35 in the side
of the retard hydraulic chamber 19 occurs, and the closed
abnormality flag xretchkf of the drain switching valve in the side
of the retard hydraulic chamber is maintained to "1".
[0254] Embodiment 4 described above measures the continuing time of
the state where the absolute value of the deviation between the
target displacement angle vvttgt and the VTC displacement angle vvt
is more than the predetermined value K7 as data representing the
convergent state and determines whether or not the drain switching
valves 34 and 35 are in a closed abnormality state, based upon
whether or not this continuing time cvvtchkc exceeds the closed
abnormality determination threshold value K8. Therefore. The closed
abnormality of each of the drain switching valves 34 and 35 can be
quickly detected during engine operating.
[0255] However, in a region where an engine rotational speed is
low, the hydraulic pressure supplied to the hydraulic control valve
21 (discharge pressure of the oil pump 27) is reduced to
deteriorate the response characteristic of the VTC displacement
angle. As a result, it is unavoidable that the convergent
characteristic of the VTC displacement angle to the target
displacement angle is deteriorated.
[0256] In consideration of it, Embodiment 4 is adapted to determine
the convergent state of the VTC displacement angle to the target
displacement angle by assuming as a precondition (one of the
abnormality diagnosis execution conditions) that the supply
hydraulic pressure to the hydraulic control valve 21 is more than a
predetermined value. Therefore, an erroneous determination of the
convergent state at a low hydraulic pressure in a low rotational
region, finally an erroneous determination of the closed
abnormality is prevented beforehand, enabling an increase on
accuracy and reliability of the abnormality diagnosis.
[0257] In this case, a hydraulic pressure sensor for detecting the
supply hydraulic pressure to the hydraulic control valve 21 may be
disposed, but Embodiment 4, considering that the hydraulic pressure
supplied to the hydraulic control valve 21 (discharge pressure of
the oil pump 27) changes with an engine rotational speed or an oil
temperature (viscosity of operating oil), is adapted to determine
whether or not the supply hydraulic pressure to the hydraulic
control valve 21 is more than a predetermined value based upon
information such as an engine rotational speed and/or an oil
temperature (for example, a cooling water). In this way, since the
supply hydraulic pressure to the hydraulic control valve 21 can be
generally estimated by using information used in an engine control,
it is not required to dispose a hydraulic pressure sensor for
detecting the supply hydraulic pressure, thereby satisfying the
demand for low costs.
[0258] It should be noted that Embodiment 4 described above
measures the continuing time of the state where the absolute value
of the deviation between the target displacement angle vvttgt and
the VTC displacement angle vvt at a change of the target
displacement angle is more than the predetermined value K7 as data
representing the convergent state, but may measure, as data
representing the convergent state, elapse time from a point where a
deviation (absolute value) between the target displacement angle
and the VTC displacement angle at a change of the target
displacement angle is more than a first predetermined value until a
point where the deviation (absolute value) is less than a second
predetermined value smaller than the first predetermined value to
determine presence/absence of the closed abnormality in each of the
drain switching valves 34 and 35 based upon this elapse time.
[0259] The present invention may be carried out with various
modifications within the spirit of the present invention, such as
by a combination of the abnormality diagnosis process of Embodiment
3 and the abnormality diagnosis process of Embodiment 4 or a
modification of a structure of the variable valve timing controller
11.
Embodiment 5
[0260] FIG. 24 shows Embodiment 5. Embodiment 5 differs in the
following point from the variable valve timing controller shown in
FIG. 1. It should be noted that components in FIG. 24 identical to
those in FIG. 1 are referred to as the identical numbers.
[0261] First, the hydraulic control valve 21 in FIG. 1 drives the
advance/retard hydraulic control valve 37 and the drain switching
valve 38 by a single linear solenoid 36, but in FIG. 24, solenoids
36 and 51 are disposed in the advance/retard hydraulic control
valve 37 and the drain switching valve 38 respectively and are
respectively controlled by the ECU 43 and 52.
[0262] Embodiment 1 shown in FIG. 1 uses, as the drain switching
valves 34 and 35, normally open-type switching valves, which are
held in an open position by springs 41 and 42 when the hydraulic
pressure is not applied to the drain switching valves 34 and 35. In
contrast, in FIG. 24, when the hydraulic pressure is not applied to
the drain switching valves 34 and 35, normally closed-type
switching valves held in a closed open position by springs 41 and
42 are used as the drain switching valves 34 and 35. In
consequence, the drain switching control function 38 is structured
to supply the hydraulic pressure at the time of closing the drain
switching valve, but in FIG. 24, is structured to stop the
hydraulic pressure supply at the time of closing the drain
switching valve.
[0263] In addition, in FIG. 1, the one-way valve and the drain
switching valve are disposed in the hydraulic pressure supply
passages corresponding to the advance hydraulic chamber and the
retard hydraulic chamber in the single vane-accommodating chamber
defined by a single vane, but in FIG. 24, the one-way valve and the
drain switching valve are disposed in the hydraulic pressure supply
passage corresponding to the advance hydraulic chamber in one
vane-accommodating chamber and also in the hydraulic pressure
supply passage corresponding to the retard hydraulic chamber in the
other vane-accommodating chamber.
Embodiment 6
[0264] Regarding the structure of Embodiment 6, mainly difference
points from FIG. 1 will be explained. It should be noted that
components in FIG. 25 identical to those in FIG. 1 are referred to
as the identical numbers.
[0265] In FIG. 1, two valves composed of a valve for switching a
hydraulic passage for an advance/retard hydraulic control function
and a valve for switching a hydraulic passage for a drain switching
control function are provided. In contrast, in FIG. 25, a single
valve achieves an advance/retard hydraulic control function and a
drain switching control function. For this reason, the hydraulic
pressure supply passages 28 and 29 are branched between the
hydraulic control valve and the one-way valve and are in
communication with the drain switching valves 34 and 35
respectively.
* * * * *