U.S. patent application number 09/920646 was filed with the patent office on 2002-02-28 for variable valve timing system.
Invention is credited to Kanada, Yoji, Komazawa, Osamu, Ogawa, Kazumi.
Application Number | 20020023602 09/920646 |
Document ID | / |
Family ID | 26597315 |
Filed Date | 2002-02-28 |
United States Patent
Application |
20020023602 |
Kind Code |
A1 |
Komazawa, Osamu ; et
al. |
February 28, 2002 |
Variable valve timing system
Abstract
A variable valve timing system includes a hydraulic pressure
circuit for controlling an operation fluid supply/discharge of the
relative rotation controlling mechanism and for controlling an
operation fluid supply/discharge of each of the advanced angle
chamber and the retarded angle chamber. The hydraulic pressure
circuit, upon initiation of the internal combustion engine,
discharges the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
until a pressure of the operation fluid reaches a controllable
pressure value. The hydraulic pressure circuit, after the pressure
of the operation fluid reaches the controllable pressure value,
effecting filling of one of the advanced and retarded angle
chambers which is at the superior side of in phase transfer
response with operation fluid, subsequently effecting filling of
the other of the advanced and retarded angle chambers, and being
adapted to supply the operation fluid to the relative rotation
controlling mechanism.
Inventors: |
Komazawa, Osamu; (Chita-shi,
JP) ; Ogawa, Kazumi; (Toyota-shi, JP) ;
Kanada, Yoji; (Gamagori-shi, JP) |
Correspondence
Address: |
Platon N. Mandros, Esquire
BURNS, DOANE, SWECKER & MATHIS, L.L.P.
P.O. Box 1404
Alexandria
VA
22313-1404
US
|
Family ID: |
26597315 |
Appl. No.: |
09/920646 |
Filed: |
August 3, 2001 |
Current U.S.
Class: |
123/90.15 ;
123/90.17 |
Current CPC
Class: |
F01L 2001/34426
20130101; F01L 2001/34483 20130101; F01L 1/34 20130101; F01L
2001/34476 20130101; F01L 2800/00 20130101; Y02T 10/12 20130101;
F02D 13/02 20130101; Y02T 10/18 20130101; F02D 41/06 20130101; F01L
1/344 20130101 |
Class at
Publication: |
123/90.15 ;
123/90.17 |
International
Class: |
F01L 001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2000 |
JP |
2000-236010 |
May 25, 2001 |
JP |
2001-157080 |
Claims
What is claimed is:
1. A variable valve timing system comprising: a housing member
provided in a driving force transmitting system in which is
transmitted a driving force from a crankshaft of an internal
combustion engine to a camshaft for controlling opening/closing of
one of an intake valve and an exhaust valve of the internal
combustion engine; the housing member rotating together with one of
the crankshaft and the camshaft; a rotor member relatively
rotatably assembled on a shoe portion provided on the housing
member and forming an advanced angle chamber and a retarded angle
chamber at a vane portion in the housing member; the rotor member
rotating together with the other of the camshaft and the
crankshaft; a relative rotation controlling mechanism which, upon
unlock operation established by being supplied with an operation
fluid, allows relative rotation between the housing member and the
rotor member and which, upon lock operation established by
discharge of the operation fluid, restricts the relative rotation
between the housing member and the rotor member at a lock phase
position in an intermediate region located at a position other than
rotation limit ends corresponding to advanced and retarded angle
phase positions, respectively; and a hydraulic pressure circuit for
controlling the operation fluid supply and discharge for the
relative rotation controlling mechanism as well as for controlling
the operation fluid supply and discharge of each of the advanced
angle chamber and the retarded angle chamber; the hydraulic
pressure circuit, upon initiation of the internal combustion
engine, discharging the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
until a pressure of the operation fluid reaches a controllable
pressure value; the hydraulic pressure circuit being adapted, after
the pressure of the operation fluid reaches the controllable
pressure value, to effect filling of one of the advanced and
retarded angle chambers which is at a superior side of in phase
transfer response characteristics with the operation fluid, and to
subsequently effect filling of the other of the advanced and
retarded angle chambers with operation fluid, the hydraulic
pressure circuit being adapted to supply the operation fluid to the
relative rotation controlling mechanism.
2. The variable valve timing system as set forth in claim 1,
wherein the hydraulic pressure circuit includes a hydraulic
pressure control valve, with a control value of the hydraulic
pressure control valve being updated, when effecting filling of one
of the advanced and retarded angle chambers which is at the
superior side of in phase transfer response characteristics, based
on the control value for retaining a phase of the relative rotation
controlling mechanism while the internal combustion engine is in a
steady operation stage before the internal combustion engine is
terminated.
3. The variable valve timing system as set forth in claim 2,
wherein the control value of the hydraulic pressure control valve
is updated based on a temperature of the operation fluid.
4. The variable valve timing system as set forth in claim 1,
wherein after elapse of a time duration measured from initiation of
the internal combustion engine a decision is made whether or not
the pressure of the operation fluid has reached the controllable
pressure.
5. The variable valve timing system as set forth in claim 4,
wherein the elapse of the time duration is changed depending on a
temperature of the operation fluid or a number of revolutions of
the internal combustion engine.
6. The variable valve timing system as set forth in claim 1,
wherein switching the supply of the operation fluid from one of the
advanced and retarded angle chambers which is at the superior side
of in phase transfer response characteristics to the other of the
advanced and retarded angle chambers is established based on a
detected value derived from a phase detection means.
7. A variable valve timing system as set forth in claim 6, wherein
the relative rotation controlling mechanism is made up of a first
control mechanism and a second control mechanism, the first control
mechanism restricting the relative rotation in an advancing angle
direction upon lock operation at the lock phase position, the
second control mechanism restricting the relative rotation in a
retarding angle direction upon lock operation at the lock phase
position, the operation fluid being permitted to flow between the
hydraulic pressure circuit and the advanced angle chamber by way of
the first control mechanism and being permitted to flow between the
hydraulic pressure circuit and the retarded angle chamber by way of
the second control mechanism, the hydraulic pressure circuit
controlling the operation fluid by a sole hydraulic pressure
control valve.
8. The variable valve timing system as set forth in claim 7,
wherein the hydraulic pressure control valve is adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or at a minimized level; (2)
discharge the operation fluid from one of the advanced and retarded
angle chambers which is at the superior side of in phase transfer
response and supply the operation fluid to the other of the
advanced and retarded angle chambers when the control current value
is at a low level; (3) interrupt the operation fluid supply to and
the operation fluid discharge from each of the advanced angle
chamber and the retarded angle chamber when the control current
value is at an intermediate level; and (4) supply the operation
fluid to one of the advanced and retarded angle chambers which is
at the superior side of in phase transfer response and discharge
the operation fluid from the other of the advanced and retarded
angle chambers when the control current value is at a high level,
the control current value being changed to the high level from zero
or the minimized level in a relatively short time duration measured
from a time when the pressure of the operation fluid becomes equal
to or greater than the value of the controllable pressure.
9. The variable valve timing system as set forth in claim 7,
wherein the hydraulic pressure control valve is adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or at a minimized level; (2)
discharge the operation fluid from one of the advanced and retarded
angle chambers and supply the operation fluid to the other of the
advanced and retarded angle chambers when the control current value
is at a low level; (3) interrupts the operation fluid supply to and
the operation fluid discharge from each of the advanced angle
chamber and the retarded angle chamber when the control current
value is at an intermediate level; and (4) supplies the operation
fluid to one of the advanced and retarded angle chambers and
discharges the operation fluid from the other of the advanced and
retarded angle chambers when the control current value is at a high
level, the control current value being set at the high level
temporarily such that thereafter the control current value is
controlled to a predetermined control current value after the
pressure of the operation fluid becomes equal to or greater than
the value of the controllable pressure, when a transfer is made
from a first condition to one of a second condition and a third
condition, the first condition permitting discharge of the
operation fluid from the relative rotation controlling mechanism
and the advanced and retarded angle chambers, the second condition
preventing supply of the operation fluid to and discharge of the
operation fluid from each of the advanced and retarded angle
chambers, the third condition permitting discharge of the operation
fluid from one of the advanced and retarded angle chambers and
supply of the operation fluid to the other of the advanced and
retarded angle chambers.
10. The variable valve timing system as set forth in claim 6,
wherein the hydraulic pressure control valve is adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or at a minimized level; (2)
discharge the operation fluid from one of the advanced and retarded
angle chambers which is at the superior side of in phase transfer
response and supply the operation fluid to the other of the
advanced and retarded angle chambers when the control current value
is at a low level; (3) interrupt the operation fluid supply to and
the operation fluid discharge from each of the advanced angle
chamber and the retarded angle chamber when the control current
value is at an intermediate level; and (4) supply the operation
fluid to one of the advanced and retarded angle chambers which is
at the superior side of in phase transfer response and discharge
the operation fluid from the other of the advanced and retarded
angle chambers when the control current value is at a high level,
the control current value being changed to the high level from zero
or the minimized level in a relatively short time duration measured
from a time when the pressure of the operation fluid becomes equal
to or greater than the value of the controllable pressure.
11. The variable valve timing system as set forth in claim 6,
wherein the hydraulic pressure control valve is adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or at a minimized level; (2)
discharge the operation fluid from one of the advanced and retarded
angle chambers and supply the operation fluid to the other of the
advanced and retarded angle chambers when the control current value
is at a low level; (3) interrupts the operation fluid supply to and
the operation fluid discharge from each of the advanced angle
chamber and the retarded angle chamber when the control current
value is at an intermediate level; and (4) supplies the operation
fluid to one of the advanced and retarded angle chambers and
discharges the operation fluid from the other of the advanced and
retarded angle chambers when the control current value is at a high
level, the control current value being set at the high level
temporarily such that thereafter the control current value is
controlled to a predetermined control current value after the
pressure of the operation fluid becomes equal to or greater than
the value of the controllable pressure, when a transfer is made
from a first condition to one of a second condition and a third
condition, the first condition permitting discharge of the
operation fluid from the relative rotation controlling mechanism
and the advanced and retarded angle chambers, the second condition
preventing supply of the operation fluid to and discharge of the
operation fluid from each of the advanced and retarded angle
chambers, the third condition permitting discharge of the operation
fluid from one of the advanced and retarded angle chambers and
supply of the operation fluid to the other of the advanced and
retarded angle chambers.
12. A variable valve timing system as set forth in claim 1, wherein
the relative rotation controlling mechanism is made up of a first
control mechanism and a second control mechanism, the first control
mechanism restricting the relative rotation in an advancing angle
direction upon lock operation at the lock phase position, the
second control mechanism restricting the relative rotation in a
retarding angle direction upon lock operation at the lock phase
position, the operation fluid being permitted to flow between the
hydraulic pressure circuit and the advanced angle chamber by way of
the first control mechanism and being permitted to flow between the
hydraulic pressure circuit and the retarded angle chamber by way of
the second control mechanism, the hydraulic pressure circuit
controlling the operation fluid by a sole hydraulic pressure
control valve.
13. The variable valve timing system as set forth in claim 12,
wherein the hydraulic pressure control valve is adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or at a minimized level; (2)
discharge the operation fluid from one of the advanced and retarded
angle chambers which is at the superior side of in phase transfer
response and supply the operation fluid to the other of the
advanced and retarded angle chambers when the control current value
is at a low level; (3) interrupt the operation fluid supply to and
the operation fluid discharge from each of the advanced angle
chamber and the retarded angle chamber when the control current
value is at an intermediate level; and (4) supply the operation
fluid to one of the advanced and retarded angle chambers which is
at the superior side of in phase transfer response and discharge
the operation fluid from the other of the advanced and retarded
angle chambers when the control current value is at a high level,
the control current value being changed to the high level from zero
or the minimized level in a relatively short time duration measured
from a time when the pressure of the operation fluid becomes equal
to or greater than the value of the controllable pressure.
14. The variable valve timing system as set forth in claim 12,
wherein the hydraulic pressure control valve is adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or at a minimized level; (2)
discharge the operation fluid from one of the advanced and retarded
angle chambers and supply the operation fluid to the other of the
advanced and retarded angle chambers when the control current value
is at a low level; (3) interrupts the operation fluid supply to and
the operation fluid discharge from each of the advanced angle
chamber and the retarded angle chamber when the control current
value is at an intermediate level; and (4) supplies the operation
fluid to one of the advanced and retarded angle chambers and
discharges the operation fluid from the other of the advanced and
retarded angle chambers when the control current value is at a high
level, the control current value being set at the high level
temporarily such that thereafter the control current value is
controlled to a predetermined control current value after the
pressure of the operation fluid becomes equal to or greater than
the value of the controllable pressure, when a transfer is made
from a first condition to one of a second condition and a third
condition, the first condition permitting discharge of the
operation fluid from the relative rotation controlling mechanism
and the advanced and retarded angle chambers, the second condition
preventing supply of the operation fluid to and discharge of the
operation fluid from each of the advanced and retarded angle
chambers, the third condition permitting discharge of the operation
fluid from one of the advanced and retarded angle chambers and
supply of the operation fluid to the other of the advanced and
retarded angle chambers.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to variable valve
timing systems. More particularly, the present invention pertains
to a variable valve timing system for controlling the opening and
closing time of an intake valve and an exhaust valve of a
vehicle-mounted internal combustion engine.
BACKGROUND OF THE INVENTION
[0002] A known variable valve timing system is described in
Japanese Patent Laid-Open Publication No.Hei. 09(1997)-324613. The
disclosed variable valve timing system includes a housing member
disposed in the driving force transmitting system for transmitting
the driving force from the crankshaft of the combustion engine to
the camshaft for controlling the opening and closing of either one
of the intake valve and the exhaust valve of the combustion engine.
The housing member rotates as a unit with one of the crankshaft and
the camshaft.
[0003] The variable valve timing system also includes a rotor
member rotatably assembled on a shoe portion provided on the
housing member. The rotor member forms an advanced angle chamber
and a retarded angle chamber at a vane portion in the housing
member and integrally rotates with one of the camshaft and the
crankshaft.
[0004] The variable valve timing system further includes a relative
rotation controlling mechanism. The relative rotation controlling
mechanism allows the relative rotation of the housing member and
the rotor member by an unlock operation by the supply of an
operation fluid. The relative rotation controlling mechanism
restricts the relative rotation of the housing member and the rotor
member at an intermediate angle phase between a retarded angle
phase and an advanced angle phase by a lock operation by the
discharge of the operation fluid. The variable valve timing system
still further includes a hydraulic pressure circuit for controlling
the supply and discharge of the operation fluid to the relative
rotation controlling mechanism as well as for controlling the
supply and discharge of the operation fluid to the advanced angle
chamber and the retarded angle chamber.
[0005] In the aforementioned variable valve timing system, to make
the internal combustion engine start in a smooth manner, the
open/close timing of one of the intake valve and the exhaust valve
is set, under the condition that the relative rotation controlling
mechanism restricts the relative rotation between the housing
member and the rotor member at a lock phase position within an
intermediate region which is located at a position other than the
rotation limit ends corresponding to the advanced and retarded
angle phase positions, respectively. Thus, at the initial stage of
the internal combustion engine, if such the restriction at the lock
phase position is not performed, the starting ability of the
internal combustion engine may become worse.
[0006] With respect to the relative rotation controlling mechanism
which restricts the relative rotation between the rotor member and
the housing member at the lock phase position, the restriction may
be inhibited due to the design of the hydraulic pressure circuit
and/or the remaining operation fluid in at least one of the
relative rotation controlling mechanism, the advanced angle
chamber, and the retarded angle chamber. In addition, in the
conventional hydraulic pressure circuit, no consideration has been
made as to how to control a hydraulic control pressure valve, which
is connected into the hydraulic pressure circuit, upon initiation
of the internal combustion engine. This results in the relative
rotation phase between the housing member and the rotor member
becoming unstable temporally when the internal combustion engine is
transferred from its initiation to steady operation condition.
[0007] Thus, a need exists for a variable valve timing system for
overcoming the aforementioned drawbacks.
SUMMARY OF THE INVENTION
[0008] In accordance with an aspect of the present invention, a
variable valve timing system includes a housing member provided in
a driving force transmitting system in which is transmitted a
driving force from a crankshaft of an internal combustion engine to
a camshaft for controlling opening/closing of one of an intake
valve and an exhaust valve of the internal combustion engine, with
the housing member rotating together with one of the crankshaft and
the camshaft. A rotor member is relatively rotatably assembled on a
shoe portion provided on the housing member and forms an advanced
angle chamber and a retarded angle chamber at a vane portion in the
housing member, with the rotor member rotating together with the
other of the camshaft or the crankshaft. A relative rotation
controlling mechanism, upon unlock operation thereof established by
being supplied with an operation fluid, allows relative rotation
between the housing member and the rotor member. The relative
rotation controlling mechanism, upon lock operation thereof
established by a discharge of the operation fluid therefrom,
restricts the relative rotation between the housing member and the
rotor member at a lock phase position in an intermediate region
located at a position other than the rotation limit ends
corresponding to the advanced and retarded angle phase positions,
respectively. A hydraulic pressure circuit controls an operation
fluid supply/discharge of the relative rotation controlling
mechanism and controls an operation fluid supply/discharge of each
of the advanced angle chamber and the retarded angle chamber. The
hydraulic pressure circuit, upon initiation of the internal
combustion engine, discharges the operation fluid from the relative
rotation controlling mechanism and the advanced and retarded angle
chambers until a pressure of the operation fluid reaches a
controllable pressure value. The hydraulic pressure circuit, after
the pressure of the operation fluid reaches the controllable
pressure value, is adapted to make one of the advanced and retarded
angle chambers which is at a superior side of the in phase transfer
response characteristic operation fluid filled, is adapted to
subsequently make the other of the advanced and retarded angle
chambers operation fluid filled, and is adapted to supply the
operation fluid to the relative rotation controlling mechanism.
[0009] The hydraulic pressure circuit includes a hydraulic pressure
control valve in which a control value of the hydraulic pressure
control valve is updated, when making one of the advanced and
retarded angle chambers which is at the superior side of the in
phase transfer response characteristic operation fluid filled, on
the basis of a control value for retaining a phase of the relative
rotation controlling mechanism while the internal combustion engine
is in a steady operation stage before operation of the internal
combustion engine is terminated. The control value of the hydraulic
pressure control valve can be amended or changed on the basis of
the temperature of the operation fluid.
[0010] After a time duration has elapsed as measured from the
initiation of the internal combustion engine, a decision is made
whether or not the pressure of the operation fluid has reached the
controllable pressure. The elapse of the time duration is amended
depending on one of the temperature of the operation fluid and the
revolution number of the internal combustion engine.
[0011] A sixth aspect of the present invention is to provide a
variable valve timing system whose gist is to modify the structure
of the first aspect, wherein switching the supply of the operation
fluid from one of the advanced and retarded angle chambers which is
at a superior side of in phase transfer response characteristic to
the other is established on the basis of a detected value derived
from phase detection means. The relative rotation controlling
mechanism is made up of a first control mechanism and a second
control mechanism, with the first control mechanism restricting the
relative rotation in an advancing angle direction upon lock
operation at the lock phase position, and the second control
mechanism restricting the relative rotation in a retarding angle
direction upon lock operation at the lock phase position. The
operation fluid is allowed to flow between the hydraulic pressure
circuit and the advanced angle chamber by way of the first control
mechanism, and the operation fluid is allowed to flow between the
hydraulic pressure circuit and the retarded angle chamber by way of
the second control mechanism. The hydraulic pressure circuit is
capable of being configured to establish that the operation fluid
can be controlled by a sole hydraulic pressure control valve.
[0012] The hydraulic pressure control valve is adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or minimized; (2) discharge
the operation fluid from one of the advanced and retarded angle
chambers which is at a superior side of in phase transfer response
and supplying the operation fluid to the other when the control
current value is at its low level; (3) interrupt the operation
fluid supply to and the operation fluid discharge from each of the
advanced angle chamber and the retarded angle chamber when the
control current value is at its intermediate level; and (4) supply
the operation fluid to one of the advanced and retarded angle
chambers which is at a superior side of in phase transfer response
and discharge the operation fluid from the other when the control
current value is at Its high level, with the control current value
being made high from zero or the minimized level in a short time
duration measured from a time when the pressure of the operation
fluid becomes equal to or above the value of the controllable
pressure.
[0013] The hydraulic pressure control valve is also adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or minimized, (2) discharge
the operation fluid from one of the advanced and retarded angle
chambers and supply the operation fluid to the other when the
control current value is at its low level; (3) interrupt the
operation fluid supply to and the operation fluid discharge from
each of the advanced angle chamber and the retarded angle chamber
when the control current value is at its intermediate level; and
(4) supply the operation fluid to one of the advanced and retarded
angle chambers and discharge the operation fluid from the other
when the control current value is at its high level, wherein the
control current value is made high temporally such that thereafter
the control current value is controlled to a predetermined control
current value after the pressure of the operation fluid becomes
equal to or above the value of the controllable pressure, when a
transfer is made from a first condition to one of a second
condition and a third condition, the first condition permitting the
discharge of operation fluid from the relative rotation controlling
mechanism and the advanced and retarded angle chambers, the second
condition making it impossible to supply the operation fluid to and
discharge the operation fluid from each of the advanced and
retarded angle chambers, and the third condition permitting the
discharge of the operation fluid from one of the advanced and
retarded angle chambers and the supply of the operation fluid to
the other of the advanced and retarded angle chambers.
[0014] Upon initiation of the internal combustion engine, in an
initial stage of the initiation of the internal combustion, the
hydraulic pressure circuit makes it possible to discharge the
operation fluid from the advancing angle and retarded angle
chambers and the relative rotation controlling mechanism. Thus, the
operation fluid remaining in each of the advancing angle and
retarded angle chambers can be discharged, resulting in that the
remaining operation fluid fails to inhibit or disturb the relative
rotation between the rotation member and the housing member, which
causes the torque variation in the driving force transmitting
system to make it possible to rotate the rotor member quickly
relative to the housing member into the lock phase position between
the advanced angle phase position and the retarded angle phase
positions. In addition, at the initial stage of the internal engine
initiation, the remaining operation fluid can be discharged from
the relative rotation controlling mechanism, which results in that
the lock operation performed therein can be made correct, thereby
making it possible to regulate in a relatively precise or correct
manner the relative rotation between the housing member and the
rotor member at the lock phase position. Thus, the starting ability
of the internal combustion engine can be improved.
[0015] Upon initiation of the internal combustion engine, in a
later stage of the initiation of the internal combustion which
comes after the pressure of the operation fluid becomes equal to or
greater than the controllable pressure value, after the hydraulic
pressure circuit makes one of the advanced and retarded angle
chambers which is at the superior side of phase transfer response
characteristic operation fluid filled, the other can be made
operation fluid filled and the relative rotation controlling
mechanism is capable of being supplied with the operation fluid.
Thus, while the internal combustion engine transfers its later
stage of the initiation operation to a steady operation stage, the
relative rotation phase between the housing member and the rotor
member can be made to substantially coincide with the lock phase
position under the condition that the regulation of the relative
rotation control mechanism is released (i. e., the locked state
between the housing member and rotor member is released), the
relative rotation phase between the housing member and the rotor
member can be made stable in an intermediate phase or region.
[0016] The variable valve timing system is configured such that the
hydraulic pressure circuit includes a hydraulic pressure control
valve in which a control value of the hydraulic pressure control
valve is updated, when making one of the advanced and retarded
angle chambers which is at a superior side of in phase transfer
response characteristic operation fluid filled, on the basis of a
control value for retaining a phase of the relative rotation
controlling mechanism while the internal combustion engine is in
normal operation before the internal combustion engine is
terminated. Thus, instrumental errors and deteriorations over time
can be compensated, which makes it possible to provide constant
operation fluid supply characteristics, thereby obtaining a
specified operation response characteristic.
[0017] The control value of the hydraulic pressure control valve is
amended on the basis of the temperature of the operation fluid. In
more detail, the opening area of the hydraulic pressure control
valve is made smaller (larger) due to lower (higher) viscosity of
the operation fluid when the temperature of the operation fluid is
high (low). This makes it possible to provide a constant operation
fluid supply characteristic freely from the temperature of the
operation fluid, thereby obtaining a specified operation response
characteristic.
[0018] After the elapse of a time duration measured from the
initiation of the internal combustion engine, a decision is made
whether or not the pressure of the operation fluid reaches the
controllable pressure. Thus, detecting whether or not the pressure
of the operation fluid reaches the controllable pressure can be
made without using a specially prepared hydraulic pressure
detecting means.
[0019] The elapse of the time duration is amended or changed
depending on one of the temperature of the operation fluid and the
revolution number of the internal combustion engine. More
specifically, making the time duration longer (shorter) when the
temperature of the operation is low (high) or when the revolution
number of the internal combustion engine is low (high) makes it
possible to provide a constant operation fluid supply
characteristic freely from the temperature of the operation fluid,
thereby obtaining a specified operation response
characteristic.
[0020] Switching the supply of the operation fluid from one of the
advanced and retarded angle chambers which is at the superior side
of the in phase transfer responsive to the other is established on
the basis of a detected value derived from a phase detection
mechanism such as a crank angle detector or cam angle sensors. This
makes it possible to establish a switching of the operation fluid
at a relative rotation phase in a precise or correct manner,
thereby continually obtaining operation response
characteristics.
[0021] The relative rotation controlling mechanism is made up of a
first control mechanism and a second control mechanism, with the
first control mechanism restricting the relative rotation in an
advancing angle direction upon lock operation at the lock phase
position, and the second control mechanism restricting the relative
rotation in a retarding angle direction upon lock operation at the
lock phase position. The operation fluid is allowed to flow between
the hydraulic pressure circuit and the advanced angle chamber by
way of the first control mechanism and is allowed to flow between
the hydraulic pressure circuit and the retarded angle chamber by
way of the second control mechanism so that the hydraulic pressure
circuit is capable of being configured to establish control of the
operation fluid by a sole hydraulic pressure control valve. Thus, a
portion of a flow passage of the operation fluid which extends from
the hydraulic pressure circuit to the advanced angle chamber can be
used as a flow passage of the operation fluid which extends from
the hydraulic pressure circuit to the first control mechanism,
while a portion of a flow passage of the operation fluid which
extends from the hydraulic pressure circuit to the retarded angle
chamber can be used as a flow passage of the operation fluid which
extends from the hydraulic pressure circuit to the second control
mechanism. Accordingly, the hydraulic pressure circuit can be made
much simpler, which results in the hydraulic pressure circuit being
capable of being produced in a much smaller size and at a lower
cost.
[0022] The hydraulic pressure control valve is adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or minimized; (2) discharge
the operation fluid from one of the advanced and retarded angle
chambers which is at a superior side of in phase transfer response
and supply the operation fluid to the other when the control
current value is at its low level; (3) interrupt the operation
fluid supply to and the operation fluid discharge from each of the
advanced angle chamber and the retarded angle chamber when the
control current value is at its intermediate level; and (4) supply
the operation fluid to one of the advanced and retarded angle
chambers which is at a superior side of in phase transfer response
and discharge the operation fluid from the other when the control
current value is at its high level. The control current value is
made high from zero or the minimized level in a relatively short
time duration measured from when the pressure of the operation
fluid becomes equal or above the value of the controllable
pressure. Thus, when the control current shifts from zero or the
minimized level (under which the operation fluid can be discharged
from the advancing and retarded angle chambers) to the high level
(under which the operation fluid can be supplied to one of the
advanced and retarded angle chambers which is at the superior side
of phase transfer response characteristic, while the operation
fluid can be discharged from the other), the time required for such
a shift can be minimized.
[0023] As a result, even though at the time when the pressure of
the operation fluid becomes equal or above the controllable
pressure value the operation fluid remains in the advancing and
retarded angle chambers and for example the retarded angle chamber
is supplied with the operation fluid under the condition that the
control current value is at a low level temporally while the
control current value shifts from zero or the minimized level to a
high level, due to the fact that the condition that the control
current value is at a low level temporally lasts for a very small
time duration and the amount of operation fluid supplied to the
retarded angle chamber is very small, the second control mechanism
fails to perform the unlock operation. In the aforementioned
temporal period, for example, if the amount of the operation fluid
supplied to the retarded angle chamber is large (i.e., the time
duration is long during which the control current value takes low
level), the supplied operation fluid is added to the remaining
operation fluid in the retarded angle chamber, which may make the
relative rotation phase between the housing member and the rotor
member unstable temporally due to unlock operation of the second
control mechanism.
[0024] The hydraulic pressure control valve is also adapted to: (1)
discharge the operation fluid from the relative rotation
controlling mechanism and the advanced and retarded angle chambers
when a control current value is zero or minimized; (2) discharge
the operation fluid from one of the advanced and retarded angle
chambers and supply the operation fluid to the other when the
control current value is at its low level; (3) interrupt the
operation fluid supply to and the operation fluid discharge from
each of the advanced angle chamber and the retarded angle chamber
when the control current value is at its intermediate level; and
(4) supply the operation fluid to one of the advanced and retarded
angle chambers and discharge the operation fluid from the other
when the control current value is at its high level. The control
current value is made high temporally such that thereafter the
control current value is controlled to a predetermined control
current value after the pressure of the operation fluid becomes
equal to or above the value of the controllable pressure, when a
transfer is made from a first condition to one of a second
condition and a third condition, with the first condition being
made possible to discharge the operation fluid from the relative
rotation controlling mechanism and the advanced and retarded angle
chambers, the second condition being made impossible to supply the
operation fluid to and discharge the operation fluid from each of
the advanced and retarded angle chambers, and the third condition
being made possible to discharge the operation fluid from one of
the advanced and retarded angle chambers and supply the operation
fluid to the other of the advanced and retarded angle chambers.
Thus, temporally changing the control current value from zero or
the minimized level to a high level makes it possible to minimize
correctly the time duration during which the control current takes
a low level (which shows that the operation fluid can be supplied
to and discharged from the retarded angle chamber and the advanced
angle chamber, respectively). This results in correct or precise
supply/discharge of the operation fluid (e.g., supplying the
operation fluid to the advanced angle chamber is made possible,
while discharging the operation fluid from the retarded angle
chamber is made possible.) and subsequent control of the control
current value (e.g., supplying the operation fluid to and
discharging the operation fluid from each of supplying the
advancing and retarded angle chambers are impossible).
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0025] The foregoing and additional features and characteristics of
the present invention will become more apparent from the following
detailed description considered with reference to the accompanying
drawing figures in which like reference numerals designate like
elements and wherein;
[0026] FIG. 1 is a schematic view of a variable valve timing system
according to an embodiment of the present invention;
[0027] FIG. 2 is a cross sectional view of a portion of the
variable valve timing system in FIG. 1 viewed from the front;
[0028] FIG. 3 is a cross sectional view of the upper lock pin
portion shown in FIG. 2;
[0029] FIG. 4 is a cross-sectional view of the lower lock pin
portion shown in FIG. 2;
[0030] FIG. 5 is an enlarged cross-sectional view of the hydraulic
pressure controlling valve shown in FIG. 1;
[0031] FIG. 6 is a cross-sectional view of the hydraulic pressure
controlling valve shown in FIG. 5 under a first energization
condition;
[0032] FIG. 7 is a cross-sectional view of the hydraulic pressure
controlling valve shown in FIG. 5 under a second energization
condition;
[0033] FIG. 8 is a cross-sectional view of the hydraulic pressure
controlling valve shown in FIG. 5 under a third energization
condition;
[0034] FIG. 9 is a cross-sectional view of the hydraulic pressure
controlling valve shown in FIG. 5 under a fourth energization
condition;
[0035] FIG. 10 is a cross-sectional view of the hydraulic pressure
controlling valve shown in FIG. 5 under fifth energization
condition;
[0036] FIG. 11 is a cross-sectional view of the hydraulic pressure
controlling valve shown in FIG. 5 under a sixth energization
condition;
[0037] FIG. 12 is a flowchart which represents the valve open/close
timing control of the variable valve timing system shown in FIG. 1;
and
[0038] FIG. 13 is a schematic view of a variable valve timing
system according to another embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0039] Referring to FIGS. 1-12, the variable valve timing system
includes a rotor member 20 assembled as one unit with the tip
portion of a camshaft 10 and a housing member 30 supported by the
rotor member 20 and rotatable within a predetermined range. The
variable valve timing system also includes a torsion spring S
disposed between the housing member 30 and the rotor member 20, and
a relative rotation controlling mechanism B (shown in FIG. 2) for
restricting relative rotation of the housing member 30 and the
rotor member 20. The variable valve timing system further includes
a hydraulic pressure circuit C for controlling the supply and
discharge of operation fluid to the relative rotation controlling
mechanism B as well as for controlling the supply and discharge of
the operation fluid to an advanced angle chamber R1 and a retarded
angle chamber R2.
[0040] The camshaft 10 has a known cam profile for controlling the
opening and closing of an intake valve and is rotatably supported
by a cylinder head 40 of the combustion engine. The camshaft 10
includes an advanced angle passage 11 and a retarded angle passage
12 extending in the axial direction of the camshaft 10. The
advanced angle passage 11 is connected to a first connecting port
101 of a hydraulic pressure controlling valve 100 via a first
passage 13 formed in the radial direction, a first annular passage
14, and a first connecting passage P1. The retarded angle passage
12 is connected to a second connecting port 102 of the hydraulic
pressure controlling valve 100 via a second passage 15 formed in
the radial direction, a second annular passage 16, and a second
connecting passage P2. The first and second passages 13, 15 formed
in the radial direction and the second annular passage 16 are
formed in the cam shaft 10. The first annular passage 14 is formed
in a stepped portion between the camshaft 10 and the cylinder head
40.
[0041] The rotor member 20 includes a main rotor 21 and a front
rotor 22 having a cylindrical shape with stepped portion assembled
as one unit on the front (i.e., left side of FIG. 1) of the main
rotor 21. The rotor member 20 is engaged with the front end of the
camshaft 10 as one unit by a bolt 50. The central inner bores of
the main rotor 21 and the front rotor 22 whose front end are closed
by a head portion of the bolt 50 communicate with the advanced
angle passage 11 provided on the camshaft 10.
[0042] The main rotor 21 includes an inner bore 21a coaxially
assembled with the front rotor 22 and four vane grooves 21b for
receiving four vanes 23 respectively and four springs 24 biasing
the vanes 23 in the radially outward direction. Respective vanes 23
assembled in the vane grooves 21b extend in the radially outward
direction and thus form the advanced angle chambers R1 and the
retarded angle chambers R2 respectively in the housing member
30.
[0043] The main rotor 21 includes four third passages 21c extending
in the radial direction in fluid communication with the advanced
angle passage 11 at the radial inner end via the central inner
bores and in fluid communication with the advanced angle chambers
R1 at the radial outer end. The main rotor 21 also includes four
passages 21d extending in the axial direction in fluid
communication with the retarded angle passage 12 and four fourth
passages 21e extending in the radial direction in fluid
communication with the respective passages 21d at the radially
inner end and in fluid communication with the retarded angle
chamber R2 at the radially outer end.
[0044] The housing member 30 includes a housing body 31, a front
plate 32, a rear thin plate 33, and five bolts 34 (shown in FIG. 2)
connecting the parts of the housing member as one unit. The housing
body 31 integrally includes a sprocket 31a on the outer rear
periphery so that the sprocket 31a is formed as one unit with the
housing body 31. The sprocket 31a is connected to the crankshaft of
the combustion engine via a timing chain and is rotated in the
clockwise direction of FIG. 2 by the driving force transmitted from
the crankshaft.
[0045] The housing body 31 has four shoe portions 31b projecting in
the radially inward direction and rotatably supports the main rotor
21 by the radial inner ends of respective shoe portions 31b. The
opposing end face of the front plate 32 and the rear thin plate 33
slidably contact the outer peripheral end face of the main rotor 21
and the end face of the respective vanes 23. The housing body 31 is
also formed with a lug 31c restricting the retarded angle phase
with the vanes 23 and a lug 31d restricting the advanced angle
phase with the vanes 23.
[0046] Upon unlocking operation of the relative rotation
controlling mechanism B through the supply of the operation fluid,
the relative rotation of the housing member 30 and the rotor member
20 is allowed. Upon locking operation of the relative rotation
controlling mechanism B through the discharge of the operation
fluid, the relative rotation of the housing member 30 and the rotor
member 20 is restricted at the intermediate angle phase or the lock
phase angle (the condition shown in FIG. 2) between the retarded
angle phase position and the advanced angle phase position. As
shown in FIGS. 2-4, the relative rotation controlling mechanism B
is provided with a pair of lock pins 61, 62 and a pair of lock
springs 63, 64. The relative rotation controlling mechanism B is
made up of a first control mechanism which includes the lock pin 61
and the lock spring 63, and a second control mechanism which
includes the look pin 62 and the lock spring 6 4.
[0047] The first control mechanism performs an unlock operation
when the operation fluid is supplied thereto from the advanced
angle passage 11, to allow relative rotation between the housing
member 30 and the rotor member 20, while the first control
mechanism performs a lock operation when the operation fluid is
discharged therefrom into the advanced angle passage 11 to
restricts at the lock phase position (the condition shown in FIG.
2) relative rotation between the housing member 30 and the rotor
member 20 in the advanced angle direction.
[0048] The second control mechanism performs an unlock operation
when the operation fluid is supplied thereto from the retarded
angle passage 12 to allows relative rotation between the housing
member 30 and the rotor member 20, while the second control
mechanism performs a lock operation when the operation fluid is
discharged therefrom into the retarded angle passage 12 to restrict
at the lock phase position (the condition shown in FIG. 2) the
relative rotation between the housing member 30 and the rotor
member 20 in the retarded angle direction.
[0049] Each of the look pin 61, 62 is slidable in the axially
outward direction within the axially extending retracting bores
32a, 32b provided in the front plate 32. Each lock pin 61, 62 is
biased in the outward direction of the retracting bores 32a, 32b by
the lock springs 63, 64. The lock springs 63, 64 are accommodated
in the retracting bores 32a, 32b. Each retracting bore 32a, 32b is
provided with open bores 32c, 32d for smoothly moving the lock pins
61, 62 in the axial direction.
[0050] The tip portion of each lock pin 61, 62 can be detachably
supported by an arc-shaped lock grooves 21f, 21g formed in the main
rotor 21. By supplying the operation fluid to the arc-shaped lock
grooves 21f, 21g, the lock pins 61, 62 move in the axially outward
direction by overcoming the biasing force (predetermined as a small
value) of the lock springs 63, 64 thus being retracted to be
accommodated in the retracting bores 32a, 32b. The tip portion of
each lock pin 61, 62 is in contact with the end face of the main
rotor 21, and is slidably movable under the contact condition.
[0051] When the rotor member 20 is positioned at the lock phase
position relative to the housing member 30 as shown in FIG. 2, each
end portion of the arc-shaped lock grooves 21f, 21g is positioned
to oppose the corresponding retracting bore 32a, 32b. Each bottom
portion of the arc-shaped lock grooves 21f, 21g is provided with
circular connecting grooves 21h, 21i and bores 21j, 21k in the
axial direction. As shown in FIGS. 2 and 3, the arc-shaped lock
groove 21f is connected with the advanced angle passage 11 through
the circular connecting groove 21h, the axially extending bore 21j,
and the radially extending bore 21c. The arc-shaped lock groove 21f
is also connected with the advanced angle chamber R1 through a
connecting groove 21m extending in the radially outward
direction.
[0052] As shown in FIGS. 2 and 4, the arc-shaped lock groove 21g is
connected with the retarded angle passage 12 through the circular
connecting groove 21i, the axially extending bore 21k, the radially
extending bore 21e, and the axially extending bore 21d. The
arc-shaped look groove 21g is also connected with the retarded
angle chamber R2 through a connecting groove 21n extending in the
radially outward direction.
[0053] The torsion spring S disposed between the housing member 30
and the rotor member 20 rotates the rotor member 20 toward the
advanced angle side relative to the housing member 30. The biasing
force of the torsion spring S is predetermined to be of a value for
canceling the biasing force (i.e., derived from the spring biasing
the intake valve in the closing direction) for the camshaft 10 and
the rotor member 20 rotating towards the retarded angle side. Thus,
good response can be obtained when the relative rotation phase of
the rotor member 20 relative to the housing member 30 is varied to
the advanced angle side.
[0054] The hydraulic pressure controlling valve 100 which is shown
in FIG. 1 constitutes the hydraulic pressure circuit C, with an oil
pump 110 actuated by the internal combustion engine and an oil
reservoir 120 of the combustion engine. A spool 104 of the
hydraulic pressure controlling valve 100 is moved in the left
direction as viewed in FIG. 1 against the urging force of a spring
105 by the energization of a solenoid 103 in response to an output
signal from an energization controlling device 200. By varying duty
value, the spool 104 is operated in the manner shown in FIGS. 5-11.
The energization controlling device 200 controls the output (i.e.,
duty value) in accordance with the operational condition of the
internal combustion by following a predetermined controlling
routine and by being based on the detected signal from sensors
(i.e., sensors 201, 202, 203, 204, 205, 206, and 207 for detecting
the crank angle, cam angle, throttle opening degree, engine rpm,
temperature of the engine cooling water, vehicle speed, and oil
pump discharge pressure, respectively).
[0055] As shown in FIG. 5 in more detail, the spool 104 is provided
with five land portions 104a, 104b, 104c, 104d, 104e, four annular
grooves 104f, 104g, 104h, 104i each formed between adjacent pairs
of land portions, and a pair of connecting bores 104j, 104k
connecting the annular grooves 104f, 104i to a discharge port 107.
The overlapping amount of each portion as shown in FIG. 5 is set to
be L1<L2<L3<L4<LS<L6.
[0056] When the spool 104 is under the condition shown in FIG. 5
(duty value=0% : de-energized condition due to the control current
value=0), the fluid communication between the supply port 106
connected to an outlet opening of the oil pump 110 and both
connecting ports 101, 102 is blocked by the land portions 104b,
104c. Both connecting ports 101, 102 are connected with the
discharge port 107 connected to the oil reservoir 120 through the
annular grooves 104f, 104i and the connecting bores 104j, 104k. The
operation fluid can be discharged from both connecting ports 101,
102 to the discharge port 107. Accordingly, the operation fluid can
be discharged from each advanced angle chamber R1, retarded angle
chamber R2, and both arc-shaped lock grooves 21f, 21g of the
relative rotation controlling mechanism B to the oil reservoir
120.
[0057] When the spool 104 is under the condition shown in FIG. 6,
the fluid communication between the supply port 106 and both
connecting ports 101, 102 is blocked by the land portions 104b,
104c. The fluid communication between the first connecting port 101
and the discharge port 107 is established by way of the annular
groove 104f and the connecting bore 104j and the operation fluid
can be discharged from the connecting port 101 to the discharge
port 107. The fluid communication between the second connecting
port 102 and the discharge port 107 is blocked by the land portions
104d, 104e. Accordingly, the operation fluid can be discharged from
each advanced angle chamber R1 and the arc-shaped lock groove 21f
of the relative rotation controlling mechanism B through the
hydraulic pressure controlling valve 100 to the oil reservoir 120.
The operation fluid can be blocked in each retarded angle chamber
R2 and the arc-shaped lock groove 21g of the relative rotation
controlling mechanism B.
[0058] When the spool 104 is under the condition shown in FIG. 7
(under which the control current value is at a low level), the
fluid communication between the supply port 106 and the first
connecting port 101 is blocked by the land portion 104b. The fluid
communication between the supply port 106 and the second connecting
port 102 is established through the annular groove 104h. The fluid
communication between the connecting port 101 and the discharge
port 107 is established through the annular groove 104f, and the
connecting bore 104j. Thus, the operation fluid can be supplied
from the supply port 106 to the second connecting port 102. Then
the operation fluid can be discharged from the connecting port 101
to the discharge port 107. Accordingly, the operation fluid can be
supplied to the retarded angle chamber R2, and the arc-shaped lock
grooves 21g of the relative rotation controlling mechanism B
through the hydraulic pressure controlling valve 100. Further, the
operation fluid can be discharged from each advanced angle chamber
RI and the arc-shaped lock groove 21f of the relative rotation
controlling mechanism B to the oil reservoir 120 by way of the
hydraulic pressure controlling valve 100.
[0059] When the spool 104 is under the condition shown in FIG. 8,
the fluid communication between the supply port 106 and the first
connecting port 101 is blocked by the land portion 104b. The fluid
communication between the supply port 106 and the second connecting
port 102 is established through the annular groove 104h. The fluid
communication between the connecting port 101 and the discharge
port 107 is blocked by the land portion 104b. Thus, the operation
fluid can be supplied from the supply port 106 to the second
connecting port 102. Accordingly, the operation fluid can be
supplied to the retarded angle chamber R2 and the arc-shaped look
groove 21g of the relative rotation controlling mechanism B through
the hydraulic pressure controlling valve 100. The operation fluid
can be blocked in each the advanced angle chamber R1 and the
arc-shaped lock groove 21f of the relative rotation controlling
mechanism B.
[0060] When the spool 104 is under the condition shown in FIG. 9
(under which the control current value is at its intermediate
level), the fluid communication between the supply port 106 and
both connecting ports 101, 102 is blocked by the land portions
104b, 104d respectively. The fluid communication between the
discharge port 107 and the connecting port 101 is blocked by the
land portion 104b while the fluid communication between the
discharge port 107 and the connecting port 102 is blocked by the
land portions 104d, 104e. Accordingly, the operation fluid can be
blocked in each advanced angle chamber R3, retarded angle chamber
R2, and both arc-shaped lock grooves 21f, 21g of the relative
rotation controlling mechanism B.
[0061] When the spool 104 is under the condition shown in FIG. 10,
the fluid communication between the supply port 106 and the land
portion 102 is blocked by the land portion 104d. The fluid
communication between the supply port 106 and the connecting port
101 is established by way of the annular groove 104g. The fluid
communication between the connecting port 102 and the discharge
port 107 is blocked by both land portions 104d, 104e. The operation
fluid can thus be supplied from the supply port 106 to the
connecting port 101. Accordingly, the operation fluid can be
supplied to each advanced angle chamber R1, and the arc-shaped lock
groove 21f of the relative rotation controlling mechanism B through
the hydraulic pressure controlling valve 100. The operation fluid
can be blocked in each retarded angle chamber R2, and the
arc-shaped lock groove 21g of the relative rotation controlling
mechanism B.
[0062] When the spool 104 is under the condition shown in FIG. 11
(under which the duty value is 100%, i.e. the control current value
is at a high level), the fluid communication between the supply
port 106 and the connecting port 102 is blocked by the land portion
104d. The fluid communication between the supply port 106 and the
connecting port 101 is established through the annular groove 104g.
The connecting port 102 is connected with the discharge port 107
through the annular groove 1041 and the connecting bore 104k. The
operation fluid can thus be supplied from the supply port 106 to
the connecting port 101. The operation fluid can be discharged from
the connecting port 102 to the discharge port 107. Accordingly, the
operation fluid can be supplied to each advanced angle chamber R1
and the arc-shaped lock groove 21f of the relative rotation
controlling mechanism B by way of the hydraulic pressure
controlling valve 100. The operation fluid can be discharged from
each retarded angle chamber R2, and the arc-shaped lock groove 21g
of the relative rotation controlling mechanism B through the
hydraulic pressure controlling valve 100.
[0063] In the present embodiment, upon initiation of operation of
the internal combustion engine, the solenoid 103 of the hydraulic
pressure control valve 100 is energized under the control of a
control routine which is previously set by the energization
controlling device 200 (using the valve open/close timing control
routine shown in FIG. 12). In this valve open/close timing control
routine, at an earlier stage of the internal combustion engine
initiation or operation during which a hydraulic supply pressure P
of the operation fluid discharged from the oil pump 110 (the oil
pump discharging pressure) reaches a controllable hydraulic
pressure P1, steps 301, 303 and 305 are executed in such order
repeatedly to maintain the hydraulic pressure control valve 100 at
a position shown in FIG. 5, whereby the operation fluid is
discharged into the oil reservoir 120 from each of the advanced
angle chambers RI, each of the retarded angle chambers R2, and the
relative rotation controlling mechanism B in the hydraulic pressure
circuit C. In step 301, it is determined whether or not an oil
filling-up flag is `0` which is to be reset to `0` upon internal
combustion engine initiation. In step 303, on the basis of the
detection signal from the oil pump discharge pressure sensor 207,
it is determined whether or not the hydraulic supply pressure P is
equal to or greater than the controllable hydraulic pressure P1. In
step 305, the solenoid 103 is energized by the duty value to make
the hydraulic pressure control valve 100 at the illustrated state
in FIG. 5.
[0064] Thus, at the earlier stage of the internal combustion engine
initiation or operation, the operation fluid remaining in the
advanced angle chambers R1 and the retarded angle chambers R2 can
be discharged therefrom, which makes the relative rotation between
the housing member 30 and the rotor member 20 free from such
remaining operation fluid which may otherwise disturb such relative
rotation. Thus, due to the torque variation in the driving force
transmission system, the rotor member 20 can be rotated quickly
relative to the housing member 30 into the lock phase position
between the advanced angle position and the retarded angle
position. In addition, at the earlier stage of the internal
combustion engine initiation, the operation fluid can be discharged
from the lock grooves 21f, 21g, thus making it possible to
establish a correct lock operation (wherein the lock pins 61, 62
are urged by the respective lock springs 63, 64). As a result, the
relative rotation between the housing member 30 and the rotor
member 20 can be restricted correctly or precisely at the lock
phase position. Thus, the starting ability of the internal
combustion engine can be improved.
[0065] Moreover, at the later stage of the internal combustion
engine initiation after the hydraulic supply pressure P discharged
from the oil pump 110 becomes equal to or above the controllable
pressure P1, until the relative rotation angle .alpha. between the
housing member 30 and the rotor member 20, which is measured from
the retarded position, exceeds a set value A which corresponds to
the pre-set lock phase position (i.e. until the advanced angle
chamber R1 is filled with the operation fluid which is at the side
of excellent phase transfer response characteristics), steps 301,
303, 307, 309 and 311 are executed repeatedly. This causes the
hydraulic pressure control valve 100 to be held at the illustrated
state in FIG. 11 (or may be held alternatively at the illustrated
state in FIG. 10). As a result, in the hydraulic pressure circuit
C, the advanced angle chambers R1 and the arc-shape lock grooves
21f can be supplied with the operation fluid.
[0066] In step 307, it is determined whether or not a retarded
angle supply flag is `1` which is to be reset to `0` by the
initialization upon internal combustion engine initiation. In step
309, the solenoid 103 is energized by the duty value to cause the
hydraulic pressure control valve 100 to be held in the illustrated
state in FIG. 11. In step 311, it is determined whether or not the
relative rotation angle a exceeds the set value A on the basis of
detection signals from the respective crank angle sensor 201 and
the cam angle sensor 202. It is to be noted that the set value A
can be amended or corrected based on the actual relative rotation
angle a of the intermediate phase angle when the hydraulic pressure
control valve 100 is held in the state illustrated in FIG. 5. This
makes it possible to compensate for instrument error.
[0067] When the relative rotation angle a exceeds the set value A,
until the relative rotation angle a becomes equal to or less than
the set value A (i.e. the retarded angle chambers R2 are filled
with the operation fluid), steps 313, 315, 319, 301, 303 and 307
are executed repeatedly to supply the operation fluid to the
retarded angle chambers R2 and the arc-shaped lock grooves 21g in
the hydraulic pressure circuit C in such manner that the supplied
operation fluid is capable of being locked in the advanced angle
chamber R1, and the arc-shaped lock groove 21f of the relative
rotation controlling mechanism B. In step 313, the solenoid 103 is
energized by the duty value to cause the hydraulic pressure control
valve 100 to be held in the illustrated state in FIG. 8. In step
315, it is determined whether or not the relative rotation angle
.alpha. is lower than the set value A on the basis of detection
signals from the respective crank angle sensor 201 and the cam
angle sensor 202. In step 319, a retarded angle supply flag is set
to `1.` It is to be noted that it is desirable to determine the
aforementioned set value A in consideration of the system
hysteresis for supplying the operation fluid in a correct or
precise fashion.
[0068] Moreover, after the relative rotation angle becomes equal to
or less than the set value A, until the internal combustion engine
is terminated, steps 301 and 330 are executed repeatedly for
performing the steady operation control routine after executing
steps 317 and 321. In step 317, the solenoid 103 is energized by
the duty value to cause the hydraulic pressure control valve 100 to
be held in the illustrated state in FIG. 9. In step 321, the oil
filling-up flag is set to `1`
[0069] Thus, while the internal combustion engine transfers from
its later stage of initiation to a steady operation stage, the
relative rotation phase between the housing member 30 and the rotor
member 20 can be substantially held in the aforementioned lock
phase position. As a result, the relative rotation phase between
the housing member 30 and the rotor member 20 can be made stable at
the intermediate phase. In addition, switching from the operation
fluid supply to the advanced angle chambers R1 to the operation
fluid supply to the retarded angle chambers R2 is performed on the
basis of the phase detection means (which is made up of the crank
angle sensor 201 and the cam angle sensor 202), which makes it
possible to establish the operating fluid supply switching action
at the predetermined relative rotation phase, thereby continually
ensuring the expected operation response characteristics.
[0070] In addition, in the present embodiment, while the internal
combustion engine is in its steady operation stage, step 330 in
FIG. 12 is executed to control the solenoid 103 of the hydraulic
pressure control valve 100 by the control routine which is pre-set
by the energization controlling device 200. This results in the
rotation phase of the rotor member 20 relative to the housing
member 30 being held in an arbitrary position between a position at
which the relative rotation phase becomes the retarded angle phase
(i.e. the volume of the advanced angle chamber R1 becomes the
minimum, while the volume of the retarded angle chamber R2 becomes
the maximum) and a position at which the relative rotation phase
becomes the advanced angle phase (i.e. the volume of the advanced
angle chamber R1 becomes the maximum, while the volume of the
retarded angle chamber R2 becomes the minimum), thereby suitably
adjusting the valve open/close timing of the intake valve between
the retarded controlled state and the advanced controlled
state.
[0071] In such a case, adjusting the rotation phase of the rotor
member 20 relative to the housing member 30 in the direction of the
advanced angle is performed such that the spool 104 of the
hydraulic pressure control valve 100 is held in the illustrated
state in FIG. 11, in which each advanced angle chamber R1 and the
arc-shaped look groove 21f of the relative rotation controlling
mechanism B is supplied with the operation fluid by way of the
hydraulic pressure control valve 100, while the operation fluid is
discharged from each of the retarded angle chambers R2 and the
arc-shaped lock groove 21g of the relative rotation controlling
mechanism B by way of the hydraulic pressure control valve 100.
[0072] At this time, the operation fluid is supplied to the
arc-shaped lock groove 21f of the relative rotation controlling
mechanism B, which results in: (1) the lock pin 61 being fitted in
the retraction groove 32a in a retraction-fit state due to the
unlock operation against the lock spring 63 or being brought into
sliding engagement with the outer surface of the main rotor 21; and
(2) the look pin 62 being brought into sliding engagement with the
outer surface of the main rotor 21 and the lock pin 62 being
slidably fitted in the arc-shaped look groove 21g, whereby the
operation fluid is supplied to and discharged from the advanced
angle chambers R1 and the retarded angle chambers R2, respectively,
thereby rotating the rotor member 20 relative to the housing member
30 in the advanced angle direction.
[0073] On the other hand, the adjustment of the rotation phase of
the rotor member 20 relative to the housing member 30 in the
direction of retarded angle is performed such that the spool 104 of
the hydraulic pressure control valve 100 is held in the state
illustrated in FIG. 7 in which each of the advanced angle chambers
R2 and the arc-shaped lock groove 21g of the relative rotation
controlling mechanism B is supplied with the operation fluid by way
of the hydraulic pressure control valve 100, while the operation
fluid is discharged from each of the retarded angle chambers R1 and
the arc-shaped lock groove 21f of the relative rotation controlling
mechanism B by way of the hydraulic pressure control valve 100.
[0074] At this time, the operation fluid is supplied to the
arc-shaped lock groove 21g of the relative rotation controlling
mechanism B, which results in: (1) the lock pin 62 being fitted in
the retraction groove 32b in a retraction-fit state due to the
unlock operation against the look spring 64 or being brought into
sliding engagement with the outer surface of the main rotor 21; and
(2) the lock pin 61 being brought into sliding engagement with the
outer surface of the main rotor 21 or the look pin 61 being
slidably fitted in the arc-shaped lock groove 21f, whereby the
operation fluid is supplied to and discharged from the retarded
angle chambers R1 and the advanced angle chambers R2, respectively,
thereby rotating the rotor member 20 relative to the housing member
30 in the retarded angle direction.
[0075] When the described embodiment is put into practice, if the
energization duty value (i.e., the control value) of the hydraulic
pressure control valve which serves for holding the phase during
steady operation of the internal combustion engine before the
internal combustion engine is terminated is made amended or changed
on the basis of the temperature of the operation fluid during
execution of step 309 in FIG. 12, compensation can be made for
instrumental errors and deteriorations over time. This makes it
possible to provide constant operation fluid supply
characteristics, thereby obtaining a specified operation response
characteristic. In such a case, if the energization duty value
(i.e., the control value) is amended, changed or updated based on
the temperature of the operation fluid which is represented by the
detection signal from the engine cooling water temperature sensor
205 in order that the opening area of the hydraulic pressure
control valve is made smaller (larger) due to a lower (higher)
viscosity of the operation fluid when the temperature of the
operation fluid is high (low), this makes it possible to provide
constant operation fluid supply characteristics freely from the
temperature of the operation fluid, thereby obtaining a specified
operation response characteristic.
[0076] When the present embodiment is put into practice, if a
decision (corresponding to step 303 in FIG. 12) is made whether or
not the discharged pressure P of the fluid from the oil pump (i.e.
the pressure of the operation fluid) reaches the controllable
pressure after a time duration elapses as measured from the
initiation of operation of the internal combustion engine (i.e. a
pre-measured time duration from initiation of the internal
combustion engine to a time when the discharge pressure P of the
oil pump 110 driven by the initiated internal combustion engine
becomes equal to or above the controllable hydraulic pressure P1),
it is possible to detect whether or not the pressure of the
operation fluid reaches the controllable pressure without using a
specially prepared hydraulic pressure detecting means such as the
aforementioned oil pump discharge pressure sensor 207, thus
reducing the cost. In such a case, by making the time duration
longer (shorter) when the temperature of the operation is low
(high) or when the revolution number of the internal combustion
engine is high (low), it is possible to provide constant operation
fluid supply characteristics freely from the temperature of the
operation fluid, thereby obtaining a specified operation response
characteristic.
[0077] In the present embodiment, the relative rotation controlling
mechanism B comprises the first control mechanism which includes
the lock pin 61 and the lock spring 63 for restricting the relative
rotation in the advancing angle direction upon lock operation at
the lock phase position and the second control mechanism which
includes the lock pin 62 and the lock spring 64 for restricting the
relative rotation in the retarded angle direction upon lock
operation at the lock phase position, thus allowing the operation
fluid to flow between the hydraulic pressure circuit C and the
advanced angle chamber R1 by way of the first control mechanism
while also allowing the operation fluid to flow between the
hydraulic pressure circuit C and the retarded angle chamber R2 by
way of the second control mechanism. As a result, the hydraulic
pressure circuit C is capable of being configured to establish
control of the operation fluid by the sole hydraulic pressure
control valve 100.
[0078] Thus, a portion of a flow passage of the operation fluid
which extends from the hydraulic pressure circuit C to the advanced
angle chamber R1 can be used as a flow passage of the operation
fluid which extends from the hydraulic pressure circuit C to the
first control mechanism, while a portion of a flow passage of the
operation fluid which extends from the hydraulic pressure circuit C
to the retarded angle chamber R2 can be used as a flow passage of
the operation fluid which extends from the hydraulic pressure
circuit to the second control mechanism. Thus, the load for
producing the passage can be reduced. Accordingly, the hydraulic
pressure circuit C can be made much simpler, which means that the
hydraulic pressure circuit C can be produced in a much smaller size
and at a lower cost.
[0079] Moreover, in the described embodiment, in addition to the
hydraulic pressure control valve 100 being capable of: (1)
discharging the operation fluid from the advanced and retarded
angle chambers when the duty value is 0% (i.e. the control current
value is zero) as shown in FIG. 5; (2) discharging the operation
fluid from the advanced angle chamber R1 and supplying the
operation fluid to the retarded angle chamber R2 when the control
current value is at its low level as shown in FIG. 7, (3)
interrupting the operation fluid supply to and the operation fluid
discharge from each of the advanced angle chamber and the retarded
angle chamber when the control current value is at its intermediate
level as shown in FIG. 9; and (4) supplying the operation fluid to
the advanced angle chamber R1 and discharging the operation fluid
from the retarded angle chamber R2 when the control current value
is ai its high level as shown in FIG. 11, the control current value
is made high from zero or the minimized level in a relatively short
time duration (required for executing steps 307 and 309 in FIG. 12)
measured from when the pressure of the operation fluid becomes
equal or greater than the value of the controllable pressure
P1.
[0080] Thus, when the control current shifts from zero or the
minimized level (under which the operation fluid can be discharged
from the advanced angle chamber R1 and retarded angle chamber R2)
to the high level (under which the operation fluid can be supplied
to one of the advanced angle chambers R1 and the retarded angle
chamber R2 which is at a superior side of the phase transfer
response characteristic, while the operation fluid can be
discharged from the other), the time required for such a shift can
be reduced or minimized.
[0081] Moreover, at a time when the pressure of the operation fluid
becomes equal to or greater than the controllable pressure value
P1, the state under which the advanced angle chamber R1, the
retarded angle chamber R2, and the relative rotation controlling
mechanism B are ready for discharging the operation fluid is
shifted to the state under which the advanced angle chamber R1 and
the retarded angle chamber R2 are ready for discharging and being
supplied with the operation fluid at the high level of the control
current value, the control current value is made temporally high
such that thereafter the control current value is controlled to the
predetermined value, resulting in that for example when the spool
104 is shifted to a position at which the operation fluid cannot be
supplied to and discharged from each of the advanced angle chamber
R1 and the retarded angle chamber R2 or the operation fluid can be
discharged from the retarded angle chamber R2 and supplied to the
advanced angle chamber R1, the time duration can be reduced or
minimized under which the spool 104 enables and non-enables the
operation fluid to be supplied to the retarded angle chamber R2 and
to be discharged from the advance angle chamber R1,
respectively.
[0082] As a result, even though at the time when the pressure of
the operation fluid becomes equal to or greater than the
controllable pressure value P1 the operation fluid remains in the
advanced angle chamber R1 and the retarded angle chamber R2 and for
example the retarded angle chamber R2 is supplied with the
operation fluid under the condition that the control current value
is at a low level temporally while the control current value shifts
from zero or a minimized level to a high level as shown in FIG. 7,
due to the fact that the state in which the control current value
is at a low level temporally lasts for a very small time duration
and the amount of the operation fluid supplied to the retarded
angle chamber R2 is very small, the lock pin 62 (i.e., the second
control mechanism) does not perform the unlock operation. In the
aforementioned temporal period, for example, if the amount of the
operation fluid supplied to the retarded angle chamber R2 is large
(i.e. the time duration is long during which the FIG. 7 illustrated
state is held), the supplied operation fluid is added to the
remaining operation fluid in the retarded angle chamber R2, which
may make the relative rotation phase between the housing member 30
and the rotor member 20 temporally unstable due to the unlock
operation of the lock pin 62 (the second control mechanism).
[0083] In the present invention, in the hydraulic pressure control
circuit C which includes only the one hydraulic pressure control
valve 100, the operation fluid is supplied to and is discharged
from each of the advance angle chambers R1, the retarded angle
chambers R2, and the relative rotation controlling mechanism B. As
an alternative, as shown in FIG. 13, a hydraulic pressure control
circuit Ca can include a set of two hydraulic pressure control
valves 100a, 100b, and the operation fluid can be also supplied to
and discharged from each of the advance angle chambers R1, the
retarded angle chambers R2, and the relative rotation controlling
mechanism B. In the FIG. 13 illustrated relative rotation
controlling mechanism, each of the lock pins 61, 62 (lock plates
could alternatively be used) is assembled in a radially extending
retracting bore formed in the housing member 31 so as to be
slidable in the axial direction in such a manner that the lock pins
61, 62 are urged to project from the retracting bore by the springs
63, 64 accommodated in the retracting bore. The relative rotation
controlling mechanism illustrated in FIG. 13 can be used as an
alternative to the relative rotation controlling mechanism B
illustrated in FIGS. 1-12.
[0084] As described above, the housing member 30 rotates as one
unit with the crankshaft and the rotor member 20 rotates as one
unit with the camshaft 10. However, the present invention can be
used for other types of variable valve timing system in which the
housing member rotates in one unit with the camshaft and the rotor
member rotates as one unit with the crankshaft. The present
invention can also be used for variable valve timing systems in
which the vane is formed as one unit with the rotor body.
[0085] Although the present invention as described above is applied
to a variable valve timing system equipped on the camshaft for
controlling the opening and closing of the intake valve, the
present invention can also be applied, as it is or by being
suitably modified, to other variable valve timing systems equipped
on the camshaft for controlling the opening and closing of the
exhaust valve. In the variable valve timing system equipped on the
camshaft for controlling the opening and closing of the exhaust
valve, sometimes the urging force of the torsion spring may be
increased for assisting the rotor member to rotate toward the
advanced angle side relative to the housing member 30. In such a
structure, due to the fact that the direction which is superior in
phase transfer response characteristics is in coincidence with the
advanced angle direction, after the pressure of the operation fluid
becomes equal to or above the controllable pressure value during
the internal combustion engine initiation, the operation fluid
fills the retarded angle chamber prior to filling the operation
fluid in the advanced angle chambers R1.
[0086] As an alternative to the aforementioned hydraulic pressure
control valve 100, it is possible to employ a hydraulic pressure
control valve which is capable of: (1) discharging the operation
fluid from the relative rotation controlling mechanism and both the
advanced and retarded angle chambers when a control current value
is at its high lever; (2) discharging the operation fluid from one
of the advanced and retarded angle chambers and supplying the
operation fluid to the other when the control current value is at
its intermediate level; (3) interrupting the operation fluid supply
to and the operation fluid discharge from each of the advanced
angle chamber and the retarded angle chamber when the control
current value is at its low level; and (4) supplying the operation
fluid to one of the advanced and retarded angle chambers and
discharging the operation fluid from the other when the control
current value is zero or at a minimized level.
[0087] In such a case, the aforementioned advantages can be
provided by making the control current value at its zero or
minimized level temporally such that thereafter the control current
value is controlled to a predetermined control current value after
the pressure of the operation fluid becomes equal to or above the
value of the controllable pressure, when a transfer is made from a
state which makes it possible to discharge the operation fluid from
the relative rotation controlling mechanism and the advanced and
retarded angle chambers to another state which makes it impossible
to supply the operation fluid to and discharge the operation fluid
from each of the advanced and retarded angle chambers or which
makes it possible to discharge the operation fluid from one of the
advanced and retarded angle chambers and supply the operation fluid
to the other of the advanced and retarded angle chambers.
[0088] The principles, preferred embodiments and modes of operation
of the present invention have been described in the foregoing
specification. However, the invention which is in tended to be
protected is not to be construed as limited to the particular
embodiment disclosed. Further, the embodiment described herein is
to be regarded as illustrative rather than restrictive. Variations
and changes may be made by others, and equivalents employed,
without departing from the spirit of the present invention.
Accordingly, it is expressly in tended that all such variations,
changes and equivalents which fall within the spirit and scope of
the present invention as defined in the claims, be embraced
thereby.
* * * * *