U.S. patent application number 11/665064 was filed with the patent office on 2009-01-29 for variable valve timing control apparatus with supplementary oil pump.
This patent application is currently assigned to AISIN SEIKI KABUSHIKI KAISHA. Invention is credited to Katsuhiko Eguchi, Takeshi Hashizume, Yoji Kanada, Masanobu Matsusaka, Shigemitsu Suzuki, Naoto Yumisashi.
Application Number | 20090025668 11/665064 |
Document ID | / |
Family ID | 35615526 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090025668 |
Kind Code |
A1 |
Matsusaka; Masanobu ; et
al. |
January 29, 2009 |
Variable valve timing control apparatus with supplementary oil
pump
Abstract
A variable valve timing control apparatus includes: a relative
rotational phase adjusting mechanism capable of adjusting a
relative rotational phase between a drive-side rotational member
and a driven-side rotational member between the most advanced angle
phase and the most retarded angle phase; and a lock mechanism
capable of locking the relative rotational phase at an intermediate
phase between the most advanced angle phase and the most retarded
angle phase; a first pump operated by a driving force of an engine;
and an electrically driven second pump operated as an electrically
driven pump. Hydraulic fluid is supplied from at least one of the
first pump and the second pump, and the second pump is capable of
operating even if the first pump is inoperative when the engine is
not running.
Inventors: |
Matsusaka; Masanobu; (Aichi,
JP) ; Yumisashi; Naoto; (Aichi, JP) ; Eguchi;
Katsuhiko; (Aichi, JP) ; Suzuki; Shigemitsu;
(Aichi, JP) ; Kanada; Yoji; (Aichi, JP) ;
Hashizume; Takeshi; (Aichi, JP) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
AISIN SEIKI KABUSHIKI
KAISHA
Kariya-shi
JP
|
Family ID: |
35615526 |
Appl. No.: |
11/665064 |
Filed: |
October 18, 2005 |
PCT Filed: |
October 18, 2005 |
PCT NO: |
PCT/JP05/19732 |
371 Date: |
April 11, 2007 |
Current U.S.
Class: |
123/90.17 ;
464/160; 701/103 |
Current CPC
Class: |
F01L 1/3442 20130101;
F01L 2001/34483 20130101; F01L 2001/34426 20130101; F01L 2001/34476
20130101 |
Class at
Publication: |
123/90.17 ;
464/160; 701/103 |
International
Class: |
F01L 1/344 20060101
F01L001/344 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2004 |
JP |
2004-305439 |
Jan 27, 2005 |
JP |
2005-019300 |
Claims
1. A variable valve timing control apparatus comprising: a
drive-side rotational member rotatable in synchronization with a
crankshaft; a driven-side rotational member positioned coaxially
with the drive-side rotational member and being rotatable
integrally with a camshaft; a fluid pressure chamber defined
between the drive-side rotational member and the driven-side
rotational member; a vane dividing the fluid pressure chamber into
an advanced angle chamber and a retarded angle chamber; a relative
rotational phase adjusting mechanism changing a position of the
vane relative to the fluid pressure chamber by supplying hydraulic
fluid to or draining hydraulic fluid from at least one of the
advanced angle chamber and the retarded angle chamber the relative
rotational phase adjusting mechanism adjusting a relative
rotational phase between the drive-side rotational member and the
driven-side rotational member between the most advanced angle
phase, in which a volume of the advanced angle chamber reaches
maximum, and the most retarded angle phase, in which a volume of
the retarded angle chamber reaches maximum; a lock mechanism
locking the relative rotational phase at an intermediate phase
between the most advanced angle phase and the most retarded angle
phase; a first pump operated by a driving force of an engine; an
electrically driven second pump wherein the hydraulic fluid is
supplied from at least one of the first pump and the second pump
and the second pump is operated when the engine is stopped; an
engine start-up predicting means for predicting a start-up of the
engine; and an engine start-up controlling means for implementing
an engine start-up control by operating the second pump when an
engine start-up is predicted by the engine start-up predicting
means.
2. (canceled)
3. (canceled)
4. (canceled)
5. (canceled)
6. A variable valve timing control apparatus according to claim 1,
wherein the engine start-up control implemented by the engine
start-up controlling means is an engine start-up lock control
wherein the lock mechanism is operated to lock the relative
rotational phase at a first start-up phase that is suitable for an
engine start-up.
7. A variable valve timing control apparatus according to claim 1,
wherein the engine start-up control implemented by the engine
start-up controlling means is an engine start-up phase control
which changes the relative rotational phase to a second start-up
phase that is different from the first start-up phase at which the
relative rotational phase is locked by the lock mechanism.
8. A variable valve timing control apparatus according to claim 7,
wherein the second start-up phase is determined based upon at least
one of an engine oil temperature, a water temperature, and intake
air temperature, and an outside air temperature.
9. A variable valve timing control apparatus according to claim 7,
wherein, after stopping the engine and prior to starting the
engine, the lock mechanism is operated so as to implement an engine
lock control whereby the relative rotational phase is locked at the
first start-up phase suitable for an engine start-up.
10. A variable valve timing control apparatus comprising: a
drive-side rotational member rotatable in synchronization with a
crankshaft; a driven-side rotational member positioned coaxially
with the drive-side rotational member and being rotatable
integrally with a camshaft; a fluid pressure chamber defined
between the drive-side rotational member and the driven-side
rotational member; a vane dividing the fluid pressure chamber into
an advanced angle chamber and a retarded angle chamber; a relative
rotational phase adjusting mechanism changing a position of the
vane relative to the fluid pressure chamber by supplying hydraulic
fluid to or draining hydraulic fluid from at least one of the
advanced angle chamber and the retarded angle chamber, the relative
rotational phase adjusting mechanism adjusting a relative
rotational phase between the drive-side rotational member and the
driven-side rotational member between the most advanced angle
phase, in which a volume of the advanced angle chamber reaches
maximum, and the most retarded angle phase, in which a volume of
the retarded angle chamber reaches maximum; a lock mechanism
locking the relative rotational phase at an intermediate phase
between the most advanced angle phase and the most retarded angle
phase; a first pump operated by a driving force of an engine; an
electrically driven second pump; wherein the hydraulic fluid is
supplied from at least one of the first pump and the second pump,
and the second pump is capable of operating when the engine is
stopped; an engine stop predicting means for predicting an engine
stop; an engine stop controlling means for implementing an engine
stop control by operating the second pump when the engine stop
predicting means predicts an engine stop; and wherein the engine
stop control implemented by the engine stop controlling means is an
engine stop lock control wherein a sweep operation, which adjusts
the relative rotational phase to the most advanced angle phase or
the most retarded angle phase, is performed, and the lock mechanism
is operated to lock the relative rotational phase at the first
start-up phase which is suitable for an engine start-up.
11. (canceled)
12. A variable valve timing control apparatus according to claim
10, further comprising: an engine stop delaying means for
outputting, to an engine controlling means for controlling the
engine, an engine stop delay signal for delaying the engine stop
for a predetermined time when the engine stop predicting means
predicts an engine stop.
13. A variable valve timing control apparatus according to claim
10, further comprising: an engine stop operation predicting means
for predicting a stop operation of the engine, wherein, when the
engine stop operation predicting means predicts the stop operation
of the engine, the engine stop controlling means allows the second
pump to perform a standby operation at a predetermined output.
14. A variable valve timing control apparatus according to claim
13, wherein the engine stop operation predicting means predicts the
stop operation of the engine based upon at least one of a
rotational speed of the engine and a running condition of a driven
system to which a driving force of the engine is transmitted.
15. A variable valve timing control apparatus according to claim 1,
wherein the first pump and the second pump are arranged in parallel
with each other.
16. A variable valve timing control apparatus according to claim 1,
wherein the second pump is arranged in series with and on the
downstream side of the first pump, and wherein a oil reservoir is
positioned between the first pump and the second pump.
17. A variable valve timing control apparatus according to claim 16
further comprising a bypass passage that allows hydraulic fluid to
bypass the second pump.
18. A variable valve timing control apparatus according to claim
10, wherein the first pump and the second pump are arranged in
parallel with each other.
19. A variable valve timing control apparatus according to claim
10, wherein the second pump is arranged in series with and on the
downstream side of the first pump, and wherein a oil reservoir is
positioned between the first pump and the second pump.
20. A variable valve timing control apparatus according to claim 19
further comprising a bypass passage that allows hydraulic fluid to
bypass the second pump.
Description
TECHNICAL FILED
[0001] This invention generally relates to a variable valve timing
control apparatus which controls opening and closing timings of one
of, or both of, an intake valve and an exhaust valve, in response
to running conditions of an engine mounted for example on a
vehicle.
BACKGROUND ART
[0002] This type of variable valve timing control apparatus is
mainly configured with a variable valve timing control unit and a
relative rotational phase adjusting mechanism. The variable valve
timing control unit incorporates, therein, a drive-side rotational
member, which rotates in synchronization with a crankshaft; a
driven-side rotational member, which is positioned coaxially with
the drive-side rotational member and rotates integrally with a
camshaft; at least one fluid pressure chamber defined in at least
one of the drive-side rotational member and the driven-side
rotational member; at least one vane dividing the fluid pressure
chamber into an advanced angle chamber and a retarded angle
chamber; and a relative rotational phase adjusting mechanism
capable of changing a position of the at least one vane relative to
the fluid pressure chamber by supplying, or draining, hydraulic
fluid to or from at least one of the advanced angle chamber and the
retarded angle chamber. The relative rotational phase adjusting
mechanism is capable of adjusting a relative rotational phase
between the drive-side rotational member and the driven-side
rotational member between the most advanced angle phase, in which a
volume of the advanced angle chamber reaches the maximum, and the
most retarded angle phase, in which a volume of the retarded angle
chamber reaches the maximum.
[0003] Further, in order to have the best condition for an engine
start-up, a lock mechanism is provided for the purpose of locking
the relative rotational phase between the drive-side rotational
member and the driven-side rotational member at an intermediate
phase between the most advanced angle phase and the most retarded
angle phase. With this lock mechanism, a locked condition is
established, for example by biasing, by a spring, a lock body
provided to the drive-side rotational member towards the
driven-side rotational member, and by inserting the lock body into
lock oil chamber formed in the driven-side rotational member,
preventing a relative rotation. This locked condition is released,
for example by applying oil pressure to the lock oil chamber to
retract the lock body towards the drive-side rotational member.
[0004] Conventionally, a variable valve timing control device has
been provided with a mechanical pump, which is operated by a
driving force from an engine, a mechanical pump which supplies
hydraulic fluid employed for adjusting a relative rotational phase
and lock oil employed for a lock operation by the lock mechanism.
This type of variable valve timing control apparatus for an
internal combustion engine is disclosed in JP2001-227308A (FIG.
6).
[0005] However, according to the above-described apparatus, supply
of hydraulic fluid and lock oil depends on a so-called engine pump.
In such a case, it is not possible to control opening and closing
timings of valves when the engine is not running. Further, for
example when an engine is started up, there is a valve timing
suitable for an engine start-up, while there is a different valve
timing suitable for a normal engine operation following the engine
start-up. In order to establish the valve timing suitable for an
engine start-up, a relative rotational phase between a driven-side
rotational member and a drive-side rotational member is fixed
(locked) at an initial phase by operating the lock mechanism. A
lock condition of the relative rotational phase includes an engine
stop lock performed immediately prior to an engine stop, and an
engine start-up lock performed at a time of an engine start-up.
[0006] In the case of the engine stop lock, the relative rotational
phase needs to be changed when an oil pressure level is declining
immediately before an engine stop. Therefore, there is no guarantee
that a reliable lock condition can be achieved.
[0007] In contrast, in the case of the engine start-up lock, the
relative rotational phase is changed after turning on an ignition
switch, i.e., when an oil pressure is unstable during an engine
start-up. Therefore, the engine start-up could possibly be delayed
by the time required for an engine start-up lock, and moreover, it
is also possible that a reliable lock may not be achieved.
[0008] Further, a lock phase, at which the lock mechanism is
operated and the relative rotational phase is fixed, is a phase or
a valve timing which enables a good engine start-up when the engine
has stopped running for a relatively long time and the engine
temperature is low. At the lock phase, it is possible to assure a
stable intake of air to the engine and sufficient level of actual
compression ratio for stable combustion. Here, if the engine is
stopped and is started again in a relatively short period of time
at the lock phase set by the lock mechanism, cranking of the engine
would require more work than required for the actual compression
ratio necessary for stable combustion, thus requiring higher input
voltage to a motor for cranking possibly with increased vibration
of the motor.
[0009] The present invention has been made in view of the above
circumstances, and provides a variable valve timing control
apparatus which enables a good and smooth engine start-up
operation.
DISCLOSURE OF THE INVENTION
[0010] According to an aspect of the present invention, a variable
valve timing control apparatus includes: a drive-side rotational
member rotatable in synchronization with a crankshaft; a
driven-side rotational member positioned coaxially with the
drive-side rotational member and being rotatable integrally with a
camshaft; at least one fluid pressure chamber defined at least one
of the drive-side rotational member and the driven-side rotational
member; at least one vane diving the fluid pressure chamber into an
advanced angle chamber and a retarded angle chamber; a relative
rotational phase adjusting mechanism capable of changing a position
of the at least one vane relative to the fluid pressure chamber by
supplying hydraulic fluid to or draining hydraulic fluid from at
least one of the advanced angle chamber and the retarded angle
chamber, the relative rotational phase adjusting mechanism being
capable of adjusting a relative rotational phase between the
drive-side rotational member and the driven-side rotational member
between the most advanced angle phase, in which a volume of the
advanced angle chamber reaches maximum, and the most retarded angle
phase, in which a volume of the retarded angle chamber reaches
maximum; a lock mechanism capable of locking the relative
rotational phase at an intermediate phase between the most advanced
angle phase and the most retarded angle phase; a first pump
operated by a driving force of an engine; and an electrically
driven second pump. Hydraulic fluid is supplied from at least one
of the first pump and the second pump, and the second pump is
capable of operating when the engine is stopped (i.e. when the
engine is not running).
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] 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
drawings, wherein:
[0012] FIG. 1 is a block view illustrating a variable valve timing
control apparatus according to a first embodiment of the present
invention;
[0013] FIG. 2 is a cross sectional view of the variable valve
timing control apparatus illustrated in FIG. 1;
[0014] FIG. 3 is a cross sectional view illustrating a lock
released condition in which a relative rotational phase control is
achieved;
[0015] FIG. 4 is a cross sectional view illustrating a locked
condition by a lock mechanism;
[0016] FIG. 5 is a cross sectional view illustrating the variable
valve timing unit in which the most retarded angle phase is
established;
[0017] FIG. 6 is an operation diagram of a control valve;
[0018] FIG. 7 is a flowchart for explaining an engine stop control
according to the first embodiment of the present invention;
[0019] FIG. 8 is a flowchart for explaining an engine stop control
according to a second embodiment of the present invention;
[0020] FIG. 9 is a flowchart for explaining an engine start-up
control;
[0021] FIG. 10 is another example of the variable valve timing
apparatus provided with another control valve in terms of a
relative rotational phase control and a lock control;
[0022] FIG. 11 is a block view illustrating a variable valve timing
control apparatus according to the second embodiment of the present
invention;
[0023] FIG. 12 is a block view illustrating a variable valve timing
control apparatus according to a third embodiment of the present
invention;
[0024] FIG. 13 is a block view illustrating a variable valve timing
control apparatus according to a fourth embodiment of the present
invention;
[0025] FIG. 14 is a flowchart for explaining an engine stop control
according to the third embodiment of the present invention; and
[0026] FIG. 15 is a flowchart for explaining an engine stop
operation predicting control according to a fourth embodiment of
the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0027] Embodiments of the present invention will be described
hereinbelow in detail with reference to the accompanying
drawings.
[0028] According to a first embodiment of the present invention, as
is illustrated in FIG. 1, variable valve timing control units 100
are provided to an intake camshaft 3a and an exhaust camshaft 3b,
respectively.
[0029] 1. An Entire Structure of a Variable Valve Timing Control
Apparatus
[0030] As is illustrated in FIG. 1, a variable valve timing control
apparatus 1 includes an intake camshaft rotational angle sensor 9a
for detecting a rotational speed of the intake camshaft 3a for
opening and closing an intake valve Ei of an engine E, an exhaust
camshaft rotational angle sensor 9b for detecting a rotational
speed of the exhaust camshaft 3b for opening and closing an exhaust
valve Eo, a crankshaft rotational angle sensor (an engine
rotational speed sensor) 9c for detecting a rotational speed of a
crankshaft 12, a throttle valve 14 located in an intake passage 13
and capable of controlling an amount of intake air, an electronic
control throttle 16, which is configured with a throttle valve
opening degree sensor 9d for detecting an opening degree of the
throttle valve 14 and a throttle motor 15 for operating the
throttle valve 14, and an electronic control unit (ECU) 9 for
controlling the electronic control throttle 16 among other
components.
[0031] As is illustrated in FIG. 1, the ECU 9 incorporates,
therein, modules that are characteristic to the first embodiment of
the present invention, such as a relative rotational phase
controlling module (i.e., a relative rotational phase controlling
means) 90, an engine start-up predicting module (i.e., an engine
start-up predicting means, E-start predicting module) 91, an engine
start-up controlling module (i.e., an engine start-up controlling
means) 92, an engine stop predicting module (i.e., an engine stop
predicting means, E-stop predicting module) 93, and an engine stop
controlling module (i.e., an engine stop controlling means) 94. The
ECU 9 serves as a control unit for controlling the variable valve
timing control apparatus 1. The ECU 9 has, among other necessary
components, one or more memory units for storing predetermined
programs and data, one or more central processing unit(s) (CPU),
and input/output interfaces. Each of the modules is a part of
software that runs in the ECU 9 together with any associated
hardware required to carry out the function(s) and algorism
associated with the module, which will be described below. The
associated hardware may be shared or not shared by different
modules. While a separate subroutine may be associated with each
module, a group of interdependent subroutines may configure a group
of modules. It is also possible to have one main program that has
all the algorisms for performing all the functions of the
modules.
[0032] Relative rotational phase control implemented by the ECU 9
is described below in terms of the variable valve control unit 100
at an exhaust side. The ECU 9 receives signals from the crankshaft
rotational angle sensor 9c and the exhaust camshaft rotational
angle sensor 9b. The relative rotational phase controlling module
90 obtains, on the basis of a difference between the received
signals, a relative rotational phase, or a phase difference of the
exhaust valve Eo relative to the angular position of the crankshaft
12. The phase difference substantially corresponds to an actual
timing for opening and closing the exhaust valve Eo.
[0033] On the other hand, in a memory module (a memory means, a
memory) 95 of the ECU 9, relative rotational phases optimized for
respective driving conditions of the engine E have been stored. The
relative rotational phase controlling module 90 is capable of
identifying the optimum relative rotational phase in response to an
actually detected engine driving condition, for example an engine
rotational speed and a temperature of cooling water. This relative
rotational phase controlling module 90 then generates and outputs a
control command by which an actual relative rotational phase is
controlled at the optimum relative rotational phase suitable for
the actual driving condition of the engine E.
[0034] As is illustrated in FIG. 2, the control command from the
ECU 9 is transmitted to a control valve 76 so as to adjust the
position of its spool appropriately. This control valve 76 is
supplied with oil pressure from a first pump 70a or a second pump
70b, which is characteristic to the first embodiment of the present
invention to effect the relative rotational phase control, the
engine start-up control, and the engine stop control. The first
pump 70a is a mechanical pump operated by a driving force from the
engine E, while the second pump 70b is an electrically driven pump
that is connected to a motor and is supplied with electric power
from an electric system. The first pump 70a is operated while the
engine E is running, primarily for implementing the relative
rotational phase control. The second pump 70b is operated primarily
for the above-described engine start-up control or engine stop
control.
[0035] According to the first embodiment of the present invention,
as is illustrated in FIG. 1, the first pump 70a and the second pump
70b are arranged in parallel with each other. With this
arrangement, since both the first pump 70a and the second pump 70b
directly communicate with an oil pan 75, even when the engine E is
stopped, it is possible to supply oil to other portions which still
remain at a high temperature, for example bearings of a
supercharger (not illustrated) by operating the second pump 70b
after the engine E has stopped running. Therefore, oil degradation
can be effectively prevented.
[0036] The ECU 9 is further capable of controlling an opening
degree of the throttle valve 14, on the basis of an engine
rotational speed, which is calculated from signals from the
crankshaft rotational angle sensor 9c, signals from a timer
provided to the ECU 9, and signals from the throttle valve opening
degree sensor 9d. Therefore, the ECU 9 can appropriately control
the engine, for example, at an engine start-up.
[0037] The ECU 9 further receives information on the position (i.e.
on or off position) of an ignition key 9e (IG key), information on
a door opening operation from a door opening and closing sensor 9f,
information on an engine oil temperature from an oil temperature
sensor 9g, information on a temperature of an engine cooling water
from a cooling water temperature sensor 9h, and information on an
outside air temperature from an air temperature sensor 9i.
[0038] 2. Variable Valve Timing Control Unit 100
[0039] As is illustrated in FIG. 2, the variable valve timing
control unit 100, for example for the exhaust side, is mainly
configured with an external rotor 2 (a drive-side rotational
member), which rotates in synchronization with the crankshaft 12 of
the engine E of a vehicle, and an internal rotor 1 (a driven-side
rotational member), which is located coaxially with the external
rotor 2 and rotates integrally with the camshaft 3.
[0040] The internal rotor 1 is integrally attached to the tip end
of respective camshaft 3a or 3b, which is supported by a cylinder
head. The external rotor 2 is mounted outside of the internal rotor
1 so as to be rotatable relative to the internal rotor 1 within a
predetermined relative rotational phase, and is mainly configured
with a front plate 22, a rear plate 23 and a timing sprocket 20
that is integrally provided to an external periphery of the
external rotor 2.
[0041] A power transmission member 24 such as a timing chain or a
timing belt is provided between the timing sprocket 20 and a gear
attached to the crankshaft 12 of the engine E.
[0042] According to the variable valve timing control unit 100
according to the first embodiment of the present invention, when
the crankshaft 12 of the engine E is rotated, rotational force is
transmitted to the timing sprocket 20 via the power transmission
member 24, and the external rotor 2 with the timing sprocket 20
rotates in the rotational direction S shown in FIG. 3. Further, the
internal rotor 1 rotates in the rotational direction S to rotate
the camshaft 3. A cam fixedly mounted on the camshaft 3 pushes down
the intake valve Ei or the exhaust valve Eo to open the valve.
[0043] (Fluid Pressure Chamber)
[0044] As is illustrated in FIG. 3, a plurality of protrusions 4,
serving as shoes projected radially inwardly from an inner
periphery of the external rotor 2, are arranged at the external
rotor 2 with intervals from each other along the rotational
direction. A fluid pressure chamber 40, which is defined between
the internal rotor 1 and the external rotor 2, is formed between
the adjacent protrusions 4 of the external rotor 2. For example,
four fluid pressure chambers 40 are formed according to the first
embodiment of the present invention. The fluid pressure chamber 40
may be formed in at least one of the external rotor 2 and the
internal rotor 1.
[0045] A vane groove 41 is formed on an external peripheral portion
of the internal rotor 1 facing each fluid pressure chamber 40. A
vane 5 for dividing the fluid pressure chamber 40 into an advanced
angle chamber 43 and a retarded angle chamber 42 in a relative
rotational direction (i.e., in the direction of arrows S1, S2 of
FIG. 3) is slidably located in the vane groove 41 in a radial
direction.
[0046] The advanced angle chamber 43 of the fluid pressure chamber
40 communicates with an advanced angle passage 11 formed at the
internal rotor 1, while the retarded angle chamber 42 communicates
with a retarded angle passage 10. The advanced angle passage 11,
and the retarded angle passage 10, for each fluid pressure chamber
40 is connected to an hydraulic circuit 7.
[0047] (Hydraulic Circuit)
[0048] As is illustrated in FIGS. 2 and 3, the hydraulic circuit 7
supplies and drains, via the advanced angle passage 11 and the
retarded angle passage 10, engine oil as hydraulic fluid for one
of, or both of, the advanced angle chamber 43 and the retarded
angle chamber 42. Thus, the hydraulic circuit 7 is capable of
acting as a relative rotational phase adjusting mechanism, whereby
a relative position of the vane 5 in each fluid pressure chamber 40
can be altered, and a relative rotational phase between the
internal rotor 1 and the external rotor 2 (hereinafter, referred to
as a relative rotational phase) can be adjusted between the most
advanced angle phase and the most retarded angle phase. The most
advanced angle phase corresponds to a relative rotational phase
between the rotors 1 and 2 where the volume of the advanced angle
chamber 43 reaches maximum, while the most retarded angle phase
corresponds to a relative rotational phase between the rotors 1 and
2 where the volume of the retarded angle chamber 42 reaches
maximum. FIG. 5 illustrates the most retarded angle phase in the
variable valve timing control unit 100.
[0049] In more detail, as is illustrated in FIGS. 1 and 2, the
hydraulic circuit 7 incorporates the first pump 70a, which is
operated by a driving force from the engine E and is capable of
supplying, to the control valve 76, engine oil as hydraulic fluid
or locking oil described later, and the electrically driven second
pump 70b. The second pump 70b is switched on and off in response to
a control command from the ECU 9. Further, the control valve 76 is
provided at a predetermined portion of the hydraulic circuit 7, for
example at a position downstream of the pump 70 and upstream of the
advanced angle chamber 43, the retarded angle chamber 42 and lock
oil chamber 62. According to the first embodiment of the present
invention, the control valve 76 is for example a solenoid-type
valve in which a position of a spool can be changed in response to
control of an amount of electricity supplied from the ECU 9, and
engine oil can be supplied and drained through its plurality of
ports. The hydraulic circuit 7 further incorporates the oil pan 75
for storing engine oil therein. The advanced angle passage 11, and
the retarded angle passage 10, of each fluid pressure chamber 40
are connected to predetermined ports of the control valve 76.
[0050] (Biasing Mechanism)
[0051] As is illustrated in FIG. 2, a torsion spring 8, which
serves as a biasing mechanism capable of biasing the relative
rotational phase between the rotors 1 and 2 towards the advanced
angle side, is provided between the internal rotor 1 and the
external rotor 2. As is illustrated in FIG. 3, this torsion spring
8 biases the external rotor 2 relative to the internal rotor 1 in
the direction denoted with S1. This torsion spring 8 enables a
start-up lock which is characteristic of the present invention.
[0052] (Lock Mechanism and Lock Oil Chamber)
[0053] A lock mechanism 6 is provided between the internal rotor 1
and the external rotor 2. The lock mechanism 6 is capable of
locking or preventing a relative rotation between the internal
rotor 1 and the external rotor 2 when the relative rotational phase
between the rotors 1 and 2 is at a predetermined intermediate phase
(lock phase) defined between the most advanced angle phase and the
most retarded angle phase. According to the first embodiment of the
present invention, this intermediate phase corresponds to the first
start-up phase.
[0054] As is illustrated in FIG. 3, the lock mechanism 6 is
configured with a lock portion 6A for a retarded angle, a lock
portion 6B for an advanced angle, both of which are provided to the
external rotor 2, and a recessed lock oil chamber 62 provided in an
external peripheral portion of the internal rotor 1.
[0055] The lock portion 6A for a retarded angle and the lock
portion 6B for an advanced angle each includes a lock body 60
provided in the external rotor 2 to be freely slidable in a radial
direction, and a spring 61 for biasing the lock body 60 in a
radially inward direction. The lock body 60 may be shaped in a
plate configuration, pin configuration and other
configurations.
[0056] The lock portion 6A for a retarded angle prevents, by
inserting the lock body 60 into the lock oil chamber 62, a relative
rotation of the internal rotor 1 relative to the external rotor 2
in the retarded angle direction (in the direction denoted with S1
in FIG. 3) from the lock phase. The lock portion 6B for an advanced
angle prevents, by inserting its lock body 60 into the lock oil
chamber 62, a relative rotation of the internal rotor 1 relative to
the external rotor 2 in the advanced angle direction (in the
direction denoted with S2 in FIG. 3) from the lock phase. That is,
in case one of the lock portion 6A for a retarded angle and the
lock portion 6B for an advanced angle is being projected into the
lock oil chamber 62, a phase change to the side of the one of the
retarded angle side and the advanced angle side is prevented while
allowing a phase change to the opposite side.
[0057] As is illustrated in FIG. 4, by inserting the lock bodies
60, 60 for the lock portion 6A for a retarded angle and for the
lock portion 6B for an advanced angle into the lock oil chamber 62,
the so-called locked condition is established in which a relative
rotational phase between the rotors 1 and 2 is locked at the
predetermined intermediate phase (the lock phase) defined between
the most advanced angle phase and the most retarded angle phase.
The lock phase is set to be a phase at which the opening and
closing timings, of the intake valve Ei and the exhaust valve Eo,
are appropriate for obtaining smooth start-up of the engine E.
[0058] The lock oil chamber 62 communicates with a lock oil passage
63 formed in the internal rotor 1, and the lock oil passage 63 is
connected to a predetermined port of the control valve 76 of the
hydraulic circuit 7. That is, the hydraulic circuit 7 is configured
to supply, or drain, engine oil as lock oil from or to the lock oil
chamber 62. When lock oil is supplied from the control valve 76 to
the lock oil chamber 62, as is illustrated in FIG. 3, the lock
bodies 60 are retracted to the side of the external rotor 2,
wherein the rotors 1 and 2 are released from the locked condition
thereby allowing a relative rotation. This release of the locked
condition is effected when, for example, a variable valve control,
such as an advanced angle control and a retarded angle control, is
commenced after a smooth engine start-up has been executed in the
intermediate locked condition.
[0059] (Oil Pressure Passage)
[0060] As is illustrated in FIGS. 1 and 6, a spool of the control
valve 76 of the hydraulic circuit 7 is selectively positioned from
a position W1 to a position W5, in proportion to or as a function
of an amount of electricity supplied from the ECU 9 to supply,
drain, or stop the flow of engine oil (either as hydraulic fluid or
lock oil) to or from the advanced angle chamber 43, the retarded
angle chamber 42, and the lock oil chamber 62.
[0061] In more detail, when the spool of the control valve 76 is
located at the position W1, a drain operation is performed wherein
lock oil in the lock oil chamber 62 as well as hydraulic fluid in
the advanced angle chamber 43 and the retarded angle chamber 42 are
drained to the oil pan 75.
[0062] When the spool of the control valve 76 is located at the
position W2 (either W2a or W2b), either one of the advanced angle
chamber 43 and the retarded angle chamber 42 is supplied with
hydraulic fluid so that the vane 5 is shifted towards the advanced
angle side or the retarded angle side while lock oil in the lock
oil chamber 62 is drained to the oil pan 75. In this case, as long
as the relative rotational phase has not reached the intermediate
phase (i.e. the lock phase), the relative rotational phase is
changed either to the advanced angle side or to the retarded angle
side. The locked condition is established when the relative
rotational phase reaches the intermediate phase.
[0063] When the spool of the control valve 76 is located at the
position W3, an advanced angle operation is implemented wherein the
relative rotation between the rotors 1 and 2 is released from the
locked condition by supplying lock oil to the lock oil chamber 62,
and hydraulic fluid is supplied to the advanced angle chamber 43
while draining hydraulic fluid from the retarded angle chamber 42,
whereby the relative rotational phase between the rotors 1 and 2 is
shifted in the advanced angle direction denoted by S2. When the
spool of the control valve 76 is located at the position W4, a
phase maintaining operation is implemented wherein the relative
rotation between the rotors 1 and 2 is released from the locked
condition, and a supply of hydraulic fluid to the advanced angle
chamber 43 and the retarded angle chamber 42 is halted, wherein the
relative rotational phase between the rotors 1 and 2 is maintained
as it is at that time.
[0064] When the spool of the control valve 76 is located at a
position W5, a retarded angle operation is implemented wherein the
relative rotation between the rotors 1 and 2 is released from the
locked condition, and the retarded angle chamber 42 is supplied
with hydraulic fluid while draining hydraulic fluid from the
advanced angle chamber 43, whereby the relative rotational phase
between the rotors 1 and 2 is shifted in the retarded angle
direction denoted by S1. The operation, and the structure, of the
control valve 76 is not limited to the above, and any modifications
can be applied.
[0065] 3. Structure Characteristic to the Present Invention
[0066] The structure of the variable valve timing control apparatus
1 according to the first embodiment of the present invention was
described above. Next, described below are controls implemented by
the variable valve timing control apparatus 1.
[0067] The variable valve timing control apparatus 1 mainly
implements the following three controls: 1) a relative rotational
phase control while the engine E is running in normal operation; 2)
an engine start-up control when the engine E is started up; and 3)
an engine stop control during the engine stop operation. According
to the first embodiment of the present invention, while the
relative rotational phase control is being implemented, the first
pump 70a is operated, and at a time of the engine start-up control
or the engine stop control, the second pump 70b is operated so as
to implement an engine start-up lock or an engine stop lock. The
relative rotational phase control is implemented by the relative
rotational phase controlling module 90, the start-up control is
implemented by the engine start-up controlling module 92, and the
engine stop control is implemented by the engine stop controlling
module 94. The memory module 95 stores, therein, second start-up
phases, which are appropriate phases for starting up the engine E
and are determined based upon at least one of an engine oil
temperature, a water temperature, an intake air temperature, and an
outside air temperature, as well as information required for the
relative rotational phase control. Therefore, by setting the
relative rotational phase at the second start-up phase appropriate
for an engine start-up, it is possible to achieve a good engine
start up. For example, by memorizing engine oil temperatures, water
temperatures, outside air temperatures and so on in a table as a
parameter, it is possible to set a relative rotational phase
experientially appropriate.
[0068] (1) Relative Rotational Phase Control
[0069] The relative rotational phase control is carried out in such
a manner that the relative rotational phase between the rotors 1
and 2 is suitable for a operating condition of the engine E. While
the relative rotational phase control is being carried out, the
lock mechanism 6 is not in operation. That is, the advanced angle
control, the retarded angle control, and the phase maintaining
control are implemented with the lock oil chamber 62 supplied with
lock oil and thus with the lock bodies 60 retracted from the lock
chamber 62 as shown in FIG. 3.
[0070] Therefore, for the duration of the relative rotational phase
control, the spool 76a of the control valve 76 is controlled to be
positioned within a range that includes the positions W3, W4 and W5
but that excludes the positions W1 and W2 as illustrated in FIG. 6.
The relative rotational phase controlling module 90 of the ECU 9
obtains, on the basis of a relationship between a rotational angle
of the crankshaft 12 and a rotational angle of the camshaft 3, the
actual value of the relative rotational phase between the external
rotor 2 and the internal rotor 1. At the same time, based on the
operating condition (an engine rotational speed, a cooling water
temperature and so on) of the engine E, the ECU 9 determines a
target value of a relative rotational phase, which is suitable for
the engine operating condition, from the values stored in the
memory module 95. Based on the relationship between the value
actually derived, and the target value, of the relative rotational
phase, the ECU 9 generates and outputs a control command to the
control valve 76. For example, this control command is outputted in
the form of an electric current value, and this electric current
value can be increased, maintained, and reduced, in accordance with
the relationship between the actual value, and the target value, of
the relative rotational phase.
[0071] (2) Start-Up Control and Stop Control
[0072] According to the first embodiment of the present invention,
not only the first pump 70a, which has been conventionally employed
and supplies oil pressure using a driving force of the engine E, is
provided, but also the electrically driven second pump 70b is
provided. Therefore, even when the engine E is not running (or
halted), it is possible, by appropriately controlling an operation
of the second pump 70b, to implement the relative rotational phase
control or to obtain the oil pressure required for carrying out a
lock control. As a result, even when an engine stop lock is
implemented in response to an engine halting, or even when the
engine start-up lock is implemented in response to a start-up of
the engine E, the second pump 70b makes it possible to effect these
controls with high reliability and precision, which was not
achieved by a conventional variable valve timing control
apparatus.
[0073] When the engine stop operation is implemented, preparations
needed for an appropriate engine start-up are made on the basis of
a signal representing this engine stop operation, e.g., an off
operation of the ignition key 9e. Also, when the engine is started
again, regardless of completion of the preparations during the
engine stop, likewise, the relevant parts are controlled in order
to achieve an appropriate engine start-up.
[0074] Next, described below are an engine stop control and an
engine start control that is carried out after the engine stop
control, with reference to flowcharts illustrated in FIGS. 7, 8 and
9. In each flowchart, the module (means), which acts each step, is
indicated on the left side thereof, and operating conditions, of
the first pump 70a and the second pump 70b, which are
characteristics of the present invention, are indicated on the
right side thereof.
[0075] (2-1) Engine Stop Control
[0076] As described above, the engine stop control is implemented
starting from the intermediate locked condition when the engine E
is started again. Or, the engine stop control is implemented so as
to establish the intermediate locked condition smoothly and easily
when the engine E is stared again. This engine stop control
involves the engine stop predicting module 93 and the engine stop
controlling module 94.
[0077] According to the first embodiment of the present invention,
there are two examples with regard to this engine stop control.
FIG. 7 illustrates the first engine stop control, while FIG. 8
illustrates the second engine stop control. In these examples, the
operation of the first pump 70a is discontinued in response to the
halting of the engine E. The subsequent operation for maintaining
the oil pressure level is carried out by the second pump 70b,
wherein the engine stop control is performed in order to perform a
predetermined intermediate lock.
[0078] The two examples differ in that the first example of the
engine stop control concerns whether a relative rotational phase is
at the intermediate lock phase, and whether a predetermined period
of time has passed after turning the ignition key 9e to its off
position whereas the second example concerns the number of sweep
operations described later is referred to as the basis for
determining termination of the engine stop control. Each example is
described in detail next.
[0079] (2-1-1) First Example of the Engine Stop Control
[0080] This engine stop control is implemented following the
flowchart illustrated in FIG. 7.
[0081] Step 71
[0082] The engine stop-predicting module 93 determines whether the
ignition key 9e is turned to its off position. If the ignition key
9e is not turned to the off position (i.e. No at step 71), the
program proceeds to step 70 so as to perform the above-described
relative rotational phase control. Since the engine E is still
running, the first pump 70a continues to operate. Further, the
spool of the control valve 76 is located at one of the positions
W3, W4 and W5 described above.
[0083] Step 72
[0084] If the ignition key 9e is turned to the off position
resulting in "Yes" in step 71, the program proceeds to step 72 to
initiate the operation of the second pump 70b on the basis of the
control command from the engine stop controlling module 94.
[0085] Steps 73 and 74
[0086] At or about the same time, the ECU 9 outputs a control
command to the control valve 76 to shift the spool of the control
valve 76 from one of the positions W3, W4, and W5 to the position
W2. That is, in order to operate the lock mechanism 6, the oil is
drained from the lock oil chamber 62. This drain operation at step
73 is continued until an engine rotational speed drops down to
zero. When the engine rotational speed reaches zero, oil supply by
the first pump 70a stops completely.
[0087] Step 75
[0088] When oil supply by the first pump 70a is completely stopped,
a sweep control is performed by oil pressure from the second pump
70b. This sweep control is a control where an advanced angle
operation is carried out over a predetermined period of time while
the oil pressure in the lock oil chamber 62 is approximately zero.
The spool of the control valve 76 is located at the position W2a
where the volume of the advanced angle chamber 43 is increased.
Normally, in such circumstances, because the engine E has stopped
after idling, the relative rotational phase is set at the most
retarded angle phase. Therefore, by gradually moving the vane 5
towards the advanced angle side by this sweep control, it is
possible to shift the relative rotational phase to the intermediate
phase, where the locked condition can be established, by means of
the oil pressure from the second pump 70b. The program then
proceeds from step 75 to step 76 during this advanced angle
operation, or after performing this advanced angle operation over
the predetermined period of time.
[0089] Step 76
[0090] The ECU 9 determines whether the relative rotational phase
has reached the intermediate phase at which the locked condition
can be established in step 76. If it has, and a positive answer yes
is obtained at step 76, the program proceeds to step 78, wherein
the engine stop control is terminated. In constant, If the
intermediate phase has not been reached, and a negative answer no
is obtained at step 76, the program proceeds to step 77.
[0091] Step 77
[0092] This decision step 77 is to set a limit to the maximum
period of time for performing the engine stop control. The ECU 9
determines, on the basis of an elapsed time after turning the
ignition key 9a to its off position, whether the sweep control at
step 75 should be repeated or the engine stop control at step 78
should be terminated. When the predetermined period of time has
passed at step 77, the program proceeds to step 78 so as to
terminate the engine stop control. On the other hand, when the
predetermined period of time has not passed at step 77, the program
returns to step 75 so as to further perform the advanced angle
operation and to shift the relative rotational phase from the
retarded angle side to the intermediate phase.
[0093] (2-1-2) Second Example of the Engine Stop Control
[0094] This engine stop control is implemented following the
flowchart illustrated in FIG. 8.
[0095] The second example of the engine stop control differs from
the first example in that the number of implementing the sweep
control at steps 85 and 86 are limited; therefore, when the
predetermined number of sweep controls is performed, the engine
stop control is terminated.
[0096] Step 81
[0097] The engine stop predicting module 93 determines whether the
ignition key 9e is turned to the off position. If it is, and a
negative answer no is obtained at step 81, the program proceeds to
step 80 so as to perform the above-described relative rotational
phase control. Since the engine E is still running, the first pump
70a remains operative. Further, the spool of the control valve 76
is located at one of the positions W3, W4 and W5.
[0098] Step 82
[0099] If the ignition key 9e was turned to the off position
resulting in "Yes" at step 71, the program proceeds to step 72 to
initiate the operation of the second pump 70b on the basis of the
control command from the engine stop controlling module 94.
[0100] Steps 83 and 84
[0101] At or about the same time, the ECU 9 outputs a control
command to the control valve 76 to shift the spool of the control
valve 76 from one of the positions W3, W4, and W5 to the position
W2. That is, in order to operate the lock mechanism 6, the oil is
drained from the lock oil chamber 62. This drain operation at step
73 is continued until an engine rotational speed drops down to
zero. When the engine rotational speed reaches zero, oil supply by
the first pump 70a stops completely.
[0102] Steps 85 and 86
[0103] When oil supply by the first pump 70a is completely stopped,
a sweep control is performed by oil pressure from the second pump
70b. This sweep control is a control where an advanced angle
operation or the retarded angle operation is repeatedly carried out
at a predetermined time interval while an oil pressure in the lock
oil chamber 62 is approximately zero. That is, at step 85, a
predetermined procedure is implemented each time step 85 is carried
out. For example, when the program passes step 85 for the first
time, the advanced angle operation is implemented for two seconds.
When the program passes step 85 for the second time, the retarded
angle operation is implemented for two seconds. When the program
passes step 85 for the third time, the advanced angle operation is
again implemented for two seconds. When the program passes step 85
for the fourth time, the retarded angle operation is again
implemented for two seconds. The spool of the control valve 76 is
located at the position W2a for the advanced angle operation or at
the position W2b for the retarded angle operation. Here, the period
of time for performing a single retarded or advanced angle
operation corresponds to a time required for the relative
rotational phase to move past the intermediate lock phase. As
described above, during one of the sweep operations, the relative
rotational phase reaches the intermediate phase, wherein the locked
condition is established appropriately. The number of times for
implementing the sweep operations is determined at step 86.
[0104] As a result, by performing the predetermined number of sweep
operations, it is possible to establish the locked condition
appropriately. Further, this algorism allows the sweep operation to
discontinue even when the locked condition is not established for
some reason, and at step 87, the engine stop control is
terminated.
[0105] (2-2) Engine Start-Up Control
[0106] This engine start-up control is implemented to achieve an
appropriate engine start-up responsive to the condition of the
starting engine E regardless of the condition of the engine at the
time of the previous engine stop operation. This engine start-up
control involves the engine start-up predicting module 91 and the
engine start-up controlling module 92.
[0107] In recent vehicles, when a door opening operation is
detected after the engine E has been inactive for a relatively long
time, the vehicle controller expects an engine start-up. Likewise,
in a keyless entry system, when a user with a vehicle key
approaches a vehicle, the system recognizes this approach, and
prepares to release the door from the locked condition. These
recognition systems can understand that an engine start-up is to be
expected soon. It is also advantageous for a variable valve timing
control apparatus to be able to prepare for an engine start-up for
the purpose of appropriately starting an engine. Therefore,
according to the first embodiment of the present invention, the
engine start-up predicting module 91 recognizes, for example on the
basis of a door opening operation, that an engine start-up is soon
performed even when the engine is not yet started.
[0108] Here, this engine start-up control is performed by operating
the second pump. In this case, preparations for starting the engine
E is made, for example by setting the relative rotational phase
between the drive-side rotational member and the driven-side
rotational member suitable for an engine start-up. Accordingly, by
performing this engine start-up control prior to an actual engine
start-up, or at or about the same time as the actual engine start
up, it is possible to start up the engine E smoothly and
appropriately.
[0109] The engine start-up control according to the first
embodiment of the present invention is illustrated by the flowchart
illustrated in FIG. 9. This engine start-up control is based on the
premise that the engine E has not been started yet. Therefore,
after the second pump 70b has been operated to bring certain parts
to speed, the engine E is started and the first pump 70a starts to
operate.
[0110] Further, according to this engine start-up control, a water
temperature of the engine cooling water is monitored. The phase for
the engine start-up may be selected between the intermediate phase
(the locked phase) at which the lock mechanism 6 is operated, and a
phase which is different from the intermediate phase depending on
the water temperature.
[0111] The engine start-up lock phase is determined to be the phase
at which an appropriate engine start-up can be performed when the
temperature of the engine E remains relatively low. Therefore, when
the temperature of the engine E is relatively high, it is not so
good to perform an engine start-up at this engine start-up lock
phase. In light of the foregoing, by setting the relative
rotational phase at the second start-up phase, which is different
from this engine start-up lock phase, it is possible to
appropriately start the engine E even when the temperature of the
engine E is still at a relatively high level. The second start-up
phase is, for example, a phase at which an engine can be
appropriately started even when the engine E is relatively
warm.
[0112] In case the second start-up phase is set when the engine E
is started, for example, after stopping the engine E and prior to
starting the engine E, a sweep operation is implemented for
adjusting the relative rotational phase to the most advanced angle
phase side or the most retarded angle phase side. By operating the
lock mechanism 6, even when the engine stop lock control is being
implemented for fixing the relative rotational phase at the first
start-up phase appropriate for an engine start-up, it is possible
to set a relative rotational phase which is suitable for an actual
engine operating condition when the engine is actually running,
thereby achieving a good engine start-up.
[0113] Step 91
[0114] The engine start-up predicting module 91 determines the
presence, or absence, of the possibility of the ignition key 9e
being turned to its on position. For example, when a signal
representing a door opening operation is detected while the engine
E is not running, the engine star-up predicting module 91
determines the presence of the possibility of the ignition key 9e
being turned to its on position. In other words, the engine
start-up predicting module 91 predicts the soon-to-be-performed
start-up of the engine E on the basis of the operation of the
ignition key 9e. The program then proceeds to step 92.
[0115] As described above, the engine start-up control is commenced
when the engine start-up is predicted. Therefore, when a door
opening operation is not detected at step 91, the program proceeds
to step 90 so as to establish an engine start-up standby condition
in which a door opening operation is waited and in which both the
first pump 70a and the second pump 70b are not operated. Further,
the spool of the control valve 76 is located at the position
W1.
[0116] Step 92
[0117] The ECU 9 detects an engine water temperature in this step.
The ECU 9 determines, on the basis of the engine water temperature,
whether the engine E should be started at the intermediate phase or
at a phase different from the intermediate phase. For example, when
the temperature of the engine E has dropped down to a normal
temperature, the engine can be started up at the intermediate
phase. When the engine E is still warm because it has not been long
since it stopped running, the engine can be started up at a
different phase, for example a phase more toward the side of the
retarded angle with respect to the intermediate phase (the lock
phase).
[0118] Step 93
[0119] Here, the ECU 9 selects an appropriate control on the basis
of the engine water temperature detected at step 92. When the
engine water temperature is lower than 20 degrees, the program
proceeds to step 93-1, wherein the intermediate locked condition is
maintained. This intermediate locked condition is established
during the engine stop control described above. Therefore, the
algorism waits for an engine start-up (step 101) in such a state
that the engine E can be started up smoothly when the engine E is
at a relatively low temperature.
[0120] Step 93-2
[0121] When the engine water temperature is higher than 20 degrees
at step 93, the program proceeds to step 93-2, wherein the second
pump 70b is operated.
[0122] Step 94
[0123] The ECU 9 calculates, on the basis of the detected engine
water temperature, a relative rotational phase which is optimal for
the engine start-up. As described above, the optimal relative
rotational phase can be obtained by selecting a value from the
relative rotational phase values stored in the memory module 95, or
by interpolating discrete values of the relative rotational phase.
The calculated relative rotational phase will be a phase different
from the intermediate lock phase, and is recognized as a target
phase employed at step 99.
[0124] Step 95
[0125] Lock oil is supplied to the lock oil chamber 62 to make it
possible for implementing the retarded angle control wherein the
relative rotational phase at step 96 is controlled to the most
retarded angle phase. The spool of the control valve 76 is located
at one of the positions W3, W4 and W5 where the locked condition is
released. Accordingly, the lock bodies 60 are released from the
lock oil chamber 62, wherein the relative rotational phase control
can be implemented.
[0126] Step 96
[0127] The relative rotational phase is controlled to the most
retarded angle phase in this step. The spool of the control valve
76 is located at the position W5 for increasing the volume of the
retarded angle chamber 42.
[0128] Step 97
[0129] The ECU 9 implements initial phase learning. In this initial
phase learning, the relative rotational phase in step 96 is
recognized as the most retarded angle phase. For example, when the
most retarded angle phase is recognized as zero degree, and the
most advanced angle phase is recognized as 60 degrees, the relative
rotational phase reached at step 96 is updated as a zero phase.
Therefore, it is possible to guarantee a zero point of the relative
rotational phase, which is determined independently for each
variable valve timing control unit.
[0130] Steps 98 and 99
[0131] As described above, when the engine water temperature is
relatively high, it is preferable to start up the engine E with the
relative phase on the side of the retarded angle with respect to
the intermediate lock phase, and an appropriate phase is obtained
at step 94. Therefore, in step 98, the ECU 9 implements, over a
predetermined period of time, a relative rotational phase control
wherein the relative rotational phase is shifted to the advanced
angle side. In step 99, the ECU 9 determines whether the relative
rotational phase reached the target phase. In this case, the spool
of the control valve 76 is located at the position W3 for the
advanced angle operation. Here, the actual relative rotational
phase is controlled to remain within plus or minus 10 degrees
relative to the target phase with respect to the crank shaft
angle.
[0132] Step 100
[0133] The ECU 9 implements a relative rotational phase maintaining
control for maintaining the relative rotational phase reached in
steps 98 and 99.
[0134] Step 101
[0135] The ECU 9 implements the engine start-up standby control by
which a start-up of the engine E is waited. As described above, the
engine start-up control is completed. According to the first
embodiment of the present invention, on the basis of the engine
water temperature, the engine start-up is waited with the relative
phase between the intermediate lock phase and a phase being
different from the intermediate lock phase. Therefore, prior to
operating the ignition key 9e, the actual relative rotational phase
can be shifted to a phase which is suitable for an actual engine
driving condition, and the engine E can then be started up, making
it possible to have a smooth and accurate engine start up. As
described above, according to the first embodiment of the present
invention, as illustrated in FIG. 2, both the relative rotational
phase control and the lock control are performed by means of a
single control valve. As is illustrated in FIG. 10, a control valve
760 (for example, a normally used three way valve) for a relative
rotational phase control and another control valve 761 (for
example, a normally used three way valve) for a lock control may be
provided. This may make it less likely to have an accidental lock
during the relative rotational phase control.
SECOND EMBODIMENT
[0136] As is illustrated in FIG. 11, in a variable valve timing
control apparatus 1 according to the second embodiment of the
present invention, the first pump 70a is arranged in series with
the second pump 70b, while other configuration thereof is
substantially identical to the first embodiment.
[0137] According to the second embodiment of the present invention,
the second pump 70b is arranged in series with and on the
downstream side of the first pump 70a. An oil reservoir 71 is
provided between the first pump 70a and the second pump 70b. This
oil reservoir 71 can store an amount of oil drawn from the oil pan
75 by the first pump 70a. When the first pump 70a is operating, oil
is supplied to each portion of the engine E via a main oil passage
72 from the oil reservoir 71, and is supplied to the variable valve
timing control unit 100 via the control valve 76. When the first
pump 70a is inoperative in response to the halt of the engine E,
the second pump 70b draws oil accumulated in the oil reservoir 71
and supplies the oil to the variable valve timing control unit 100.
Here, a volume of the oil reservoir 71 can be determined to be the
volume required for the variable valve timing control unit 100 to
implement the engine start-up control or the engine stop control.
For example, if the vane 5 is shifted from the most advanced angle
side to the most retarded angle side with a volume change of about
30 cc, it is preferable that the oil reservoir 71 has a volume of
approximately 60 cc which substantially corresponds to an amount
required for the variable valve timing control unit 100 to cause
the vane 5 to move from one end to the other and back. One of
advantages in positioning the first pump 70a and the second pump
70b in series, compared with a configuration in which the second
pump 70b draws oil directly from the oil pan 75 is that it is
possible to reduce the drawing power of the second pump 70b. With a
reduced drawing power requirement for the second pump 70b, it is
possible to employ a smaller-sized electric pump as the second pump
70b, thereby enabling to reduce the size, and weight, of the entire
structure of the variable valve timing control unit 100. As another
advantage of arranging the first pump 70a and the second pump 70b
in series, the total length of piping can be reduced, thereby
making it possible to reduce an efficiency loss due to frictional
resistance of the flowing oil.
[0138] It is preferable to provide a bypass passage 73 for
bypassing the second pump 70b. Therefore, if the second pump 70b
becomes inoperative and an oil passage in the second pump 70b is
closed, the oil drawn by the first pump 70a can be fed to the
bypass passage 73 thus assuring secure oil supply to the variable
valve timing control unit 100 while the engine E is running.
THIRD EMBODIMENT
[0139] As is illustrated in FIG. 12, a variable valve timing
control apparatus 1 according to a third embodiment of the present
invention is provided with an engine stop delaying module (an
engine stop delaying means) 96, while other configuration thereof
is substantially identical to the first embodiment. Further, FIG.
12 illustrates an engine-controlling module (an engine controlling
means) 110 which is not shown in other figures. However, this
engine-controlling module 110 is provided in the apparatus 1
according to the other embodiments.
[0140] According to this third embodiment, in accordance with
predetermined conditions described later, the engine stop control
is performed in such a manner that the predetermined intermediate
lock is carried out after delaying the halting of the operation of
the first pump 70a. The operations relevant to this engine stop
control are illustrated in the flowchart in FIG. 14. In this
flowchart, the module (means), which carries out respective step,
is indicated on the left side thereof, and operating conditions of
the first pump 70a and the second pump 70b, which are
characteristic of the present invention, are indicated on the right
side thereof.
[0141] Here, when the engine stop predicting module 93 predicts the
stop of the engine E, i.e., when the ignition key 9e is turned to
the off position, the engine stop delaying module 96 outputs an
engine stop delay signal for delaying an engine stop for a
predetermined time (e.g., one or two seconds) from the time an
engine stop is predicted. An elapsed time after outputting an
engine stop delay signal, and an elapsed time after actually
stopping the engine E are used as bases for decisions made in the
algorism.
[0142] This engine stop control is implemented by the flowchart
illustrated in FIG. 14.
[0143] Step 131
[0144] The engine stop-predicting module 93 determines whether the
ignition key 9e is turned to the off position. If it is not and a
negative answer no is obtained at step 131, the program proceeds to
step 130 so as to perform the above-described relative rotational
phase control. Since the engine E is still running, the first pump
70a continues to operate. Further, the spool of the control valve
76 is located at one of the positions W3, W4 and W5.
[0145] Steps 132 and 133
[0146] If the ignition key 9e is turned to the off position
resulting in "Yes" in step 131, the program proceeds to step 132,
and the engine stop delaying means module 96 outputs an engine stop
delay signal to the engine controlling module 110. At or about the
same time, in step 133, the second pump 70b is started on the basis
of a control command from the engine stop-controlling module 94.
Here, because an engine stop is delayed, the operation of the first
pump 70a is continued for a predetermined period of time, the first
pump 70a acts to assist the operation of the second pump 70b whose
operation was just started. Therefore, it is possible to reduce a
load applied to the second pump 70b when the engine E is started.
Therefore, a smaller electric pump may be used, which leads to a
smaller and lighter apparatus 1.
[0147] Steps 134 and 135
[0148] At or about the same time, the control valve 76 receives a
control command to shift the spool of the control valve 76 from one
of the positions W3, W4 and W5 to the position W2. That is, in step
134, the oil pressure in the lock oil chamber 62 is drained in
order to operate the lock mechanism 6. After this drain operation
in step 134, a sweep control is implemented in step 135.
[0149] Step 136
[0150] Following step 135, at step 136, the ECU 9 determines
whether the relative rotational phase has reached the intermediate
phase at which the locked condition is established. If it has and a
positive answer yes is obtained in step 136, the program proceeds
to step 137, and the engine E is stopped at step 138. On the other
hand, if the phase has not reached the intermediate phase and a
negative answer no is obtained in step 136, the program proceeds to
step 139.
[0151] Step 139
[0152] This decision step 139 is to set a limit to the maximum
period of time for performing the engine stop control. The ECU 9
determines, on the basis of an elapsed time after the ignition key
9a is turned to the off position, whether the sweep control in step
135 should be repeated or the engine stop control in step 149
should be performed. When the predetermined period of time was
determined to have passed in step 139, the program proceeds to step
140 to stop the engine E. On the other hand, if the predetermined
period of time has not passed, the program returns to step 135 so
as to further perform the sweep control.
[0153] Steps 141 and 142
[0154] After halting the engine E in step 140, the sweep control is
implemented in step 141. Because the engine E has halted, this
sweep control is performed only by the second pump 70b. In step
142, the ECU 9 determines whether the relative rotational phase has
reached the intermediate phase at which the locked condition is
established. If it has and a positive answer yes is obtained in
step 142, the program proceeds to step 143. On the other hand, if
the phase has not reached the intermediate phase and a negative
answer no is obtained at step 142, the program proceeds to step
144.
[0155] Step 144
[0156] Here, the ECU 9 determines whether a predetermined period of
time has passed after halting the engine E at step 140. When the
predetermined period of time is determined to have passed, the
program proceeds to step 143 to terminate the engine stop control.
When the predetermined period of time is determined to have not
passed, the program returns to step 142, wherein the sweep control
is further implemented by the second pump 70b.
[0157] As described above, irrespective of implementing the engine
start-up control, in the variable valve timing control apparatus 1
with the first pump 70a and the second pump 70b, for example, it is
preferable to include the engine stop predicting module 93 for
predicting an engine stop, and an engine stop controlling module
94, which, when the engine stop predicting module 93 predicts an
engine stop, implements an engine stop control by operating the
second pump 70b. These arrangements make it possible to obtain an
oil pressure reliably when the engine E is stopped, and further to
complete preparations for an engine startup while the engine E is
not running.
FOURTH EMBODIMENT
[0158] As is illustrated in FIG. 13, the variable valve timing
control apparatus according to the fourth embodiment of the present
invention is provided with an engine stop operation predicting
module (an engine stop operation predicting means) 97, while other
configuration thereof is substantially identical to the first
embodiment. FIG. 13 illustrates a driven system 160 which is not
illustrated in other figures. However, this driven system 160 is
provided in the apparatus 1 according to the other embodiments.
[0159] Here, an engine stop operation predicting control is
performed by means of the engine stop operation-predicting module
97. The engine stop operation predicting control is a one
implemented based on a predetermined predicted condition such as an
engine stop operation (e.g. a turning of the ignition key 9e to its
off position). This predetermined condition is described later.
[0160] The engine stop operation-predicting module 97 is
incorporated in the ECU 9 illustrated in FIG. 13, for example, and
can be hardware or software or a combination of both. This engine
stop operation-predicting module 97 outputs, in response to
prediction of the stop operation of the engine E, a command to the
engine stop-controlling module 94 such that a standby operation of
the second pump 70b is performed with a predetermined output (e.g.,
20 to 30% output). With this arrangement, because the second pump
70b is preliminarily operated before an actual engine stop
operation, it allows the second pump 70b to make sufficient output
immediately after the engine stop operation. Therefore, the
arrangement makes it possible to smoothly and rapidly supply oil to
the variable valve timing control unit 100 by the second pump 70b
immediately after the engine stop. This engine stop operation
predicting control is described below with reference to the
flowchart illustrated in FIG. 15.
[0161] Steps 151, 152, 153
[0162] In step 151, the engine stop operation-predicting module 97
determines whether engine stop operation predicting conditions are
satisfied. The engine stop operation predicting conditions can be
determined on the basis of one or the other of the rotational speed
of the engine E, and a running condition of the driven system 160
to which the driving force of the engine E is transmitted. For
example, the engine rotational speed is considered to satisfy the
engine stop operation predicting condition if it is at or
approximately at an idling speed (for example, the idling
rotational speed +500 rpm or less). Further, for example, the
running condition of the driven system 160 to which driving force
of the engine E is transmitted is determined on the basis of a
position of a shift lever or a speed value indicated by a
speedometer. Specifically, when the transmission is in the park
position, the engine stop operation predicting condition is
satisfied if the vehicle speed outputted, for example, by a vehicle
speed sensor is substantially zero. Since the engine stop operation
is predicted on the basis of at least one piece of information, it
is possible to supply oil more reliably to the variable valve
timing control apparatus 1 immediately after an engine stop. When
the engine stop operation predicting module 97 determines that the
engine stop operation predicting condition is satisfied, in
response to a control command from the engine stop controlling
module 94, the standby operation of the second pump 70b is started
(step 152). During this time, the relative rotational phase control
is implemented (step 153) as long as the engine E is running. If
the engine stop operation predicting condition is not satisfied,
this routine is repeated.
[0163] Step 154
[0164] Here, the engine stop predicting module 93 determines
whether the ignition key 9e was turned to its off position. When
the ignition key 9e is determine to have been turned to the off
position, the program proceeds to step 157, wherein the engine stop
control described above is implemented. That is, steps 73-78 in
FIG. 7, steps 83-87 in FIG. 8, and steps 134-143 in FIG. 14 are
carried out. On the other hand, if the ignition key 9e is
determined to have not been turned to the off position, the program
proceeds to step 155.
[0165] Steps 155 and 156
[0166] In step 155, the engine stop operation predicting module 97
determines whether the engine stop operation predicting condition
is not satisfied any more. For example, when the position of the
shift lever is shifted from the parking position to a drive
position (D), when the engine rotational speed increases to well
beyond the idling speed, or when the speedometer indicates a
non-zero speed, the ECU 9 determines that the engine stop operation
predicting condition is not satisfied any more. In this case, the
program proceeds to step 156, wherein the engine stop operation
predicting control is terminated.
[0167] As described above, the arrangement according to the fourth
embodiment of the present invention makes it possible to
preliminarily operate the second pump 70b prior to turning the
ignition key 9e to the off position. Therefore, the second pump 70b
is brought to its full capacity immediately after the first pump
70a is stopped in response to the engine stop, thereby allowing
smooth and stable supply of oil to the variable valve controlling
unit 100 immediately after an engine stop.
FURTHER EMBODIMENT
[0168] According to the above described embodiments, the second
pump 70b is employed as an oil pressure source for the variable
valve timing control unit 100. Alternatively or in addition to any
of the foregoing embodiments, this second pump can be used to pump
lubrication oil to the bearing portion of a supercharger of a
vehicle. With this arrangement, because an oil pump can be operated
even after an engine stop, by supplying oil to a bearing portion of
a supercharger that still remains at a high temperature, the
bearing seizure can be prevented. Further, it is possible to
effectively prevent engine oil from being degraded, which on
occasions occurs due to seizures of mechanical parts. As described
above, because oil can be circulated only to a portion of a
supercharger after an engine stop, a turbo timer, which circulates
oil by running the engine, is not needed. Further, because the
engine does not have to be running, the arrangement helps improve
fuel efficiency.
[0169] A system for detecting an intake air temperature is not
described above. This intake air temperature can be detected by
providing a temperature-detecting unit at an air intake portion.
The second start-up phase, which is needed for the engine start-up
control, can be determined on the basis of this temperature.
[0170] The principles, the preferred embodiments and mode of
operation of the present invention have been described in the
foregoing specification. However, the invention, which is intended
to be protected, is not to be construed as limited to the
particular embodiment disclosed. Further, the embodiments described
herein are 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 intended that all such
variations, changes and equivalents that fall within the spirit and
scope of the present invention as defined in the claims, be
embraced thereby.
* * * * *