Information
-
Patent Grant
-
6386164
-
Patent Number
6,386,164
-
Date Filed
Tuesday, November 2, 199924 years ago
-
Date Issued
Tuesday, May 14, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 123 9012
- 123 9015
- 123 9016
- 123 9017
- 123 9018
- 123 9031
-
International Classifications
-
Abstract
A valve timing control apparatus for an internal combustion engine has a lock pin that is movably provided in an accommodation hole of one of vanes of a rotor. A screw portion is formed along part of the outer circumference of the lock pin, which is fixed to a shaft of a motor. When hydraulic pressure control is performed to maintain a housing and the rotor in a predetermined intermediate phase, the lock pin moves in the axial direction of a cam shaft in response to rotation of the motor independently of the hydraulic pressure control, and engages a lock recess portion formed in a sprocket.
Description
The disclosure of Japanese Patent Application No. HEI 10-347198 filed on Dec. 7, 1998 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve timing control apparatus for variably controlling at least one of intake valves and exhaust valves of an internal combustion engine, in accordance with an operation state of the engine.
2. Description of the Related Art
Various valve timing control apparatuses have been put into practice which change valve timings of intake valves and exhaust valves in accordance with an operation state of an internal combustion engine. Further, Japanese Patent Publication Laid-Open No. HEI 9-324613 discloses a valve timing control apparatus employing vanes equipped with a lock pin. The outline of the valve timing control apparatus disclosed in this publication will be described with reference to
FIGS. 11 and 12
.
FIG. 11
schematically shows the structure of the valve timing control apparatus. As shown in
FIG. 11
, the valve timing control apparatus is composed of a variable valve timing mechanism (VVT)
212
, an oil control valve (OCV)
240
, an engine control unit (not shown) and the like. The engine control unit drive-controls the OCV
240
in accordance with operation control of the engine, thereby variably controlling the VVT
212
.
FIG. 12
shows in cross section the structure of the VVT
212
. The VVT
212
is provided on an intake-side cam shaft
211
(FIG.
11
). The VVT
212
is composed of a housing
216
integrated with a sprocket
217
, a rotor
219
incorporated in the housing
216
and the sprocket
217
, a rear plate
214
(FIG.
11
), and a front cover
220
(
FIG. 11
) for covering a front face of the housing
216
. The rotor
219
, the rear plate
214
and the like are coupled to the intake-side cam shaft
211
by means of bolts or the like such that they can rotate integrally. Further, as shown in
FIG. 12
, the rotor
219
is provided with four vanes
224
that are arranged at, equal intervals along an outer circumference thereof and project radially.
On the other hand, in the aforementioned VVT
212
, the sprocket
217
has a in substantially cylindrical shape and is disposed on the outer circumference of the rear plate
214
. The sprocket
217
is supported such that it can rotate relative to the rear plate
214
and the intake-side cam shaft
211
. The sprocket
217
is drivingly coupled to a crank shaft (not shown). When the engine is started (comes into operation), the sprocket
217
rotates clockwise in
FIG. 12
in response to rotation of the crank shaft.
Further, the housing
216
, which is integrated with the sprocket
217
, is provided with four protruding portions
225
, which are arranged at equal intervals. Four concave portions
226
are provided to accommodate the vanes
224
of the rotor
219
, and each of the concave portions
226
is formed between adjacent ones of the in protruding portions
225
. With each of the vanes
224
being disposed in a corresponding one of the concave portions
226
, an advancement hydraulic chamber
230
and a retardation hydraulic chamber
231
are formed on opposite sides of each of the vanes
224
.
In a state where oil is supplied to both the hydraulic chambers
230
and
231
, the rotor
219
and the sprocket
217
are coupled to each other at a relative angle corresponding to a pressure balance of the oil. In response to rotation of the sprocket
217
, the rotor
219
and the cam shaft
211
are rotated.
If the pressure in the retardation hydraulic chamber
231
becomes higher than the pressure in the advancement hydraulic chamber
230
, the vanes
224
rotate counterclockwise in FIG.
12
. Then, each of the vanes
224
comes into abutment on one of the inner walls of a corresponding one of the protruding portions
225
. In this state, the cam shaft
211
is in its most receded position with respect to the crank shaft. At this moment, the valve timing of intake valves (not shown), which are driven in response to rotation of the cam shaft
211
, is also most retarded. Conversely, if the pressure in the advancement hydraulic chamber
230
becomes higher than the pressure in the retardation hydraulic chamber
211
, the vanes
224
rotate clockwise in FIG.
12
. Then, each of the vanes
224
comes into abutment on the other of the inner walls of a corresponding one of the protruding portions
225
. In this state, the cam shaft
211
is in its most advanced position with respect to the crank shaft. At this moment, the valve timing of the intake valves (not shown), which are driven in response to rotation of the cam shaft
211
, is also most advanced.
The VVT
212
is provided with a lock mechanism employing a lock pin. This lock mechanism will now be described.
As shown in
FIG. 12
, an accommodation hole
232
, which extends parallel to the axis of the cam shaft
211
, is formed in one of the protruding portions
225
within the housing
216
. A lock pin
233
is slidably accommodated in the accommodation hole
232
. A lock recess portion
234
(FIG.
11
), which is opposed to the accommodation hole
232
, is formed in the rear plate
214
.
Further, a ring-like hydraulic chamber
249
is formed in the accommodation hole
232
. The pressure of the oil supplied to the hydraulic chamber
249
acts on the lock pin
233
. For this purpose, the oil supplied to the advancement hydraulic chamber
230
or the retardation hydraulic chamber
231
is used. The lock pin
233
is constantly urged in such a direction as to engage the lock recess portion
234
by a spring
235
, which is interposed between the lock pin
233
and the front cover
220
.
Accordingly, in the case where the force acting on the lock pin
233
based on an oil pressure becomes smaller than an urging force of the spring
235
, for example, in stopping or starting, the engine, the lock pin
233
engages the lock recess portion
234
of the rear plate
214
at a predetermined angle relative to the sprocket
217
. At this moment, the sprocket
217
is mechanically coupled to the rear plate
214
. Then, the rotor
219
and the sprocket
217
rotate integrally, for example, at a predetermined relative angle β as shown in FIG.
12
. That is, each of the vanes
224
is advanced from the most retarded position by the predetermined angle β.
On the contrary, in the case where the force acting on the lock pin
233
based on an oil pressure becomes greater than an urging force of the spring
235
, for example, during operation of the engine, the lock pin
233
is released from the lock recess portion
234
. Then, relative rotation between the sprocket
217
and the rear plate
214
, namely, between the sprocket
217
and the rotor
219
is permitted.
In this valve timing control apparatus, the relative angle between the rotor
219
and the sprocket
217
at the time of engagement of the lock pin
233
with the lock recess portion
234
is selected so as to correspond to a valve timing that does not adversely affect startability of the engine. By selecting the relative angle between the two members, as it were, as an intermediate phase, the variable valve timing zone can be enlarged in response to assurance of startability of the engine.
In this manner, by setting the phase between the rotor
219
and the sprocket
217
at the time of engagement of the lock pin
233
with the lock recess portion
234
to the aforementioned intermediate phase, desirable characteristics of the valve timing control apparatus such as assurance of startability of the engine, enlargement of the variable valve timing zone, and the like can be obtained. However, an apparatus that performs the aforementioned phase control or operation control of the lock pin
233
using a hydraulic pressure in the engine cannot avoid the following inconveniences.
That is, according to the aforementioned valve timing control apparatus, in a state where the hydraulic pressure is low in stopping or starting the engine, appropriate engagement of the lock pin
233
cannot be achieved. In other words, the controllability in the aforementioned intermediate phase deteriorates significantly.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a valve timing control apparatus for an internal combustion engine that can enhance controllability in an intermediate phase even when stopping or starting the engine with certainty.
In a first aspect of the present invention, there is provided a valve timing control apparatus for an internal combustion engine which includes a rotational body, a cam shaft, a hydraulic chamber, a hydraulic pressure control system, a lock mechanism and a lock mechanism control system. The rotational body is drivingly coupled to an output shaft of the internal combustion engine. The cam shaft drivingly opens and closes valves of the internal combustion engine. The hydraulic chamber changes a rotational phase between the output shaft and the cam shaft through supply of a hydraulic pressure. The hydraulic chamber is formed between the rotational body and the cam shaft. The hydraulic pressure control system controls the hydraulic pressure supplied to the hydraulic chamber. The lock mechanism maintains the rotational phase between the output shaft and the cam shaft in a predetermined intermediate phase through a force other than the hydraulic pressure. The lock mechanism control system drivingly controls the lock mechanism.
In this construction, the control for driving the lock mechanism, namely, for preventing and allowing relative rotation between the output shaft and the cam shaft is performed independently of the hydraulic pressure control for controlling the rotational phase between the output shaft and the cam shaft. Therefore, even in the case where the hydraulic pressure in the internal combustion engine becomes unstable, for example, when stopping or starting the vehicle-mounted engine, the control for maintaining the intermediate phase can be suitably performed by driving the lock mechanism with a high degree of reliability. Accordingly, the engine can be stopped or started at predetermined valve timings.
In the aforementioned aspect, the lock mechanism control system may be designed to electrically drive-control the lock mechanism.
In this construction, the lock mechanism is electrical drive-controlled. Therefore, even in the case where the hydraulic pressure becomes unstable, for example, when stopping or starting the vehicle-mounted engine, the control for maintaining the intermediate phase can be suitably performed by the lock mechanism with a high degree of reliability.
Further, in the aforementioned first aspect, the lock mechanism control system may be designed to drive-control the lock mechanism through a hydraulic pressure control system that is provided separately from the hydraulic pressure control system.
In this construction, the lock mechanism is drive-controlled through a hydraulic pressure control system that is provided separately from the hydraulic pressure control system. Therefore, even in the case where the hydraulic pressure becomes unstable, for example, in stopping or starting the vehicle-mounted engine, the control for maintaining the intermediate phase can be suitably performed by driving the lock mechanism with a high degree of reliability.
In a second aspect of the present invention, there is provided a valve timing control apparatus for an internal combustion engine including a rotational body, a cam shaft, a hydraulic chamber, a hydraulic pressure control system, a lock mechanism and an electric stopper. The rotational body is drivingly coupled to an output shaft of the internal combustion engine. The cam shaft drivingly opens and closes valves of the internal combustion engine. The hydraulic chamber changes a rotational phase between the output shaft and the cam shaft through supply of a hydraulic pressure. The hydraulic chamber is formed between the rotational body and the cam shaft. The hydraulic pressure control system controls the hydraulic pressure supplied to the hydraulic chamber. The lock mechanism maintains the rotational phase between the output shaft and the cam shaft in a predetermined intermediate phase through a force other than the hydraulic pressure. The electric stopper selectively restrains relative rotation between the cam shaft and the rotational body in the predetermined intermediate phase so as to assist retainment of the intermediate phase by the lock mechanism.
This construction is provided with the electric stopper for selectively restraining relative rotation between the cam shaft and the rotational body in the predetermined intermediate phase so as to assist retainment of the intermediate phase by the lock mechanism. Thus, the locking operation can be reliably performed by means of the lock mechanism, and the aforementioned intermediate phase can be suitably controlled.
The electric stopper makes it possible to set the lock pin opposed to its engagement hole and to ensure engagement of the lock pin thereinto.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and further objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings, wherein:
FIG. 1
is a partial sectional view of a valve timing control apparatus according to a first embodiment of the present invention;
FIG. 2
is a sectional view taken along line II—II in
FIG. 2
;
FIG. 3
is a sectional view showing an example of operation mode of an OCV;
FIG. 4
is a schematic view of the overall structure of the first embodiment;
FIG. 5A
is an enlarged sectional view of a state where a lock pin of the first embodiment is in engagement with a lock recess portion, and
FIG. 5B
is an enlarged sectional view of a state where the lock pin of the first embodiment has been released from the lock recess portion;
FIG. 6
is a partial sectional view of a valve timing control apparatus according to a second embodiment of the present invention;
FIG. 7
is a sectional view taken along line VII—VII in
FIG. 6
;
FIG. 8
is a schematic view of the overall structure of the second embodiment;
FIG. 9
is a schematic view of the overall structure of a valve timing control apparatus according to a third embodiment of the present invention;
FIG. 10
is an enlarged sectional view of a lock pin and the like of the third embodiment;
FIG. 11
is a schematic view of the overall structure of an example of the valve timing control apparatus; and
FIG. 12
is a partial sectional view of the structure of the valve timing control apparatus.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
A valve timing control apparatus of an internal combustion engine according to a first embodiment of the present invention will now be described with reference to
FIGS. 1
to
5
,
As shown in
FIGS. 1 and 2
, the valve timing control apparatus of this embodiment is mainly composed of a variable valve timing mechanism (VVT)
12
, an oil control valve (OCV)
40
, an engine control unit (ECU)
65
and the like. The engine control apparatus
65
performs variable control of the VVT
12
by controlling the OCV
40
in accordance with an operation control of the engine.
FIG. 1
mainly shows a cross-sectional structure of the VVT
12
at a leading end portion of an intake-side cam shaft (hereinafter referred to simply as “cam shaft”)
11
, and shows a partial cross-sectional structure of the OCV
40
.
FIG. 2
is a sectional view take along line II—II in
FIG. 1
, while
FIG. 1
is a sectional view taken along line I—I in FIG.
2
.
Referring to
FIGS. 1 and 2
, the structure of respective portions of the valve timing control apparatus according to the first embodiment will be described.
As shown in
FIG. 1
, an upper end portion of cylinder head
14
and a bearing cap
15
rotatably support a cam shaft
11
through a journal portion
11
a
thereof. The cam shaft
11
has at a leading end portion thereof a radially widened portion
11
b
. A sprocket
17
, which is rotatably provided on an outer periphery of the radially widened portion
11
b
, has outer teeth
17
a
. A timing chain (not shown) is hung over outer peripheries of the outer teeth
17
a
. The timing chain transmits a rotational force of a crank shaft (not shown) to the sprocket
17
.
The cam shaft
11
has on the side of its base end (on the right side in
FIG. 1
) a plurality of cams (not shown). These cams abut on upper end portions of intake valves (not shown). In accordance with a rotation of the cam shaft
11
, the respective cams open and close the intake valves.
A housing
16
and a housing cover (front cover)
20
are fixed to the sprocket
17
by means of a bolt
21
and rotate integrally with the sprocket
17
. On the other hand, a rotor
19
, which is attached to a leading end face of the cam shaft
11
by means of a bolt
22
, is fixed to the cam shaft
11
by means of a knock pin (not shown) and rotates integrally with the cam shaft
11
.
As shown in
FIG. 2
, the rotor
19
is provided with a cylindrical boss
23
and four vanes (pressure-receiving vanes)
24
. The boss
23
is located in a central portion of the rotor
19
. The four vanes
24
are formed at angular intervals of 90° around the boss
23
.
The housing
16
has therein four protruding portions
25
, which protrude toward the center and are disposed at predetermined intervals. Each of concave portions
26
formed between two of the protruding portions
25
accommodates a corresponding one of the vanes
24
of the rotor
19
. An outer peripheral face of each of the vanes
24
is in contact with an inner peripheral face of the concave portion
26
. An inner peripheral face of each of the protruding portions
25
is in contact with an outer peripheral face of the boss
23
.
The vanes
24
have grooves
27
, each of which is formed in an outer peripheral face of a corresponding one of the vanes
24
. Each of seal plates
28
is disposed in a corresponding one of the grooves
27
. Each of the seal plates
28
is in contact with the inner peripheral face of a corresponding one of the concave portions
26
, each of which is formed between two of the protruding portions
25
. Each of leaf springs
29
designed as an elastic member is disposed between one of the seal plates
28
and a bottom wall of a corresponding one of the groove portions Each of the leaf springs
29
presses a corresponding one of the seal plates
28
toward an inner peripheral face of a corresponding one of the conclave portions
26
. Each of the seal plates
28
seals a gap between an outer peripheral face of a corresponding one of the vanes
24
and an inner peripheral face of a corresponding one of the concave portions
26
formed in the housing
16
.
On the other hand, a housing cover
20
(
FIG. 1
) covers leading end side faces of the housing
16
and the rotor
19
. Each of the vanes
24
divides each of four spaces surrounded by the cover
20
, a corresponding one of the concave portions
26
of the housing
16
, the boss
23
and a side plate
18
into two hydraulic chambers
30
and
31
.
To advance the valve timing, oil is supplied to the advancement hydraulic chamber
30
, which is located on the side of the vane in a direction (hereinafter referred to as a “retardation direction”) opposite to a rotational direction (indicated by an arrow in
FIG. 2
) of the sprocket
17
. On the other hand, retard the valve timing, oil is supplied to the retardation hydraulic chamber
31
, which is located on the side of the vane in the same direction (hereinafter refer red to as an “advancement” direction) as the rotational direction of the sprocket
17
.
As shown in
FIGS. 1 and 2
, one of the vanes
24
is circular in cross section and has an accommodation hole
32
extending along an axial direction of the cam shaft
11
. A lock pin
33
is movably disposed in the accommodation hole
32
. As shown in
FIG. 1
, a screw portion
33
a
is formed along part of an outer circumference of the lock pin
33
. The lock pin
33
is fixed to a shaft
70
a
of a motor
70
and moves in the axial direction of the cam shaft
11
in accordance with rotation of the motor
70
. The lock pin
33
engages a lock recess portion
34
formed in the sprocket
17
, whereby the location of the rotor
19
relative to the sprocket
17
(the housing
16
) is fixed as shown in
FIG. 2
such that a side face of each of the vanes
24
on the side of the advancement hydraulic chamber
30
is spaced apart from a corresponding one of the protruding portions
25
by a predetermined phase α. Thereby, relative rotation between the rotor
19
and the housing
16
is restrained, and the cam shaft
11
and the housing
16
rotate integrally. Restraint of relative rotation between the rotor
19
and the housing
16
by means of the lock pin
33
prevents generation of noise resulting from an unstable operation state of the VVT
12
, for example, at the time of engine start. Such noise is generated, for example, when the side face of each of the vanes
24
on the side of the advancement hydraulic chamber
30
comes into abutment on the side face of a corresponding one of the protruding portions
25
.
In this embodiment, as shown in
FIG. 4
, electric power for driving the motor
70
for moving the lock pin
33
is supplied from a power source portion
80
through a line
71
. The power source portion
80
is provided at an end portion of the cam shaft
11
opposite to a side where the VVT
12
is provided.
The power source portion
80
has a generation portion
81
and a storage portion
82
. The generation portion
81
is composed of a fixture (excitation) portion
81
a
provided in the cylinder head
14
and a rotation portion
81
b
provided on the cam shaft
11
. The generation portion
81
generates electricity as the cam shaft
11
rotates. The storage portion
82
is composed of, for example, a secondary cell, and stores the electricity generated by the generation portion
81
. The electricity stored in the storage portion
82
is supplied to the motor
70
at a predetermined timing based on a command from the ECU
65
. During this period, the lock pin
33
engages the lock recess portion
34
or is released therefrom. Thus, in this embodiment, the lock pin
33
engages and is released from the lock recess portion
34
independently of hydraulic pressure control for controlling phases of the housing
16
, and the rotor
19
. The hydraulic pressure control will be described later.
Hydraulic passages P
1
and P
2
, through which oil is supplied to or drained from the respective advancement hydraulic chambers
30
an d the respective retardation chambers
31
, will now be described with reference to
FIGS. 1
to
3
.
As shown in
FIG. 1
, an advancement-side oil path
38
and a retardation-side oil path
39
are formed inside the cylinder head
14
. The oil paths
38
and
39
are Hi connected to first and second ports
55
and
56
of the OCV
40
respectively. The first and second ports
55
and
56
will be described later. The OCV
40
leads to an oil pan
43
through an oil filter
41
, a pump
13
and an oil strainer
42
.
The advancement-side oil path
38
leads to an oil passage
4
,
6
formed inside the cam shaft
11
through an oil groove
44
formed over the entire circumference of the journal
11
a
and an oil hole
45
formed inside the journal
11
a
. The oil passage
46
opens on the side of a leading end thereof to an annular space
47
, which is defined by a base end side inner peripheral portion of the boss
23
of the rotor
19
, the bolt
22
and the sprocket
17
. As shown in
FIG. 2
, four oil holes
48
that are radially formed in part of the respective vanes
24
and the respective protruding portions
25
connect the annular space
47
with the respective advancement hydraulic chambers
30
. The oil supplied to the annular space
47
is supplied to the respective advancement hydraulic chambers
30
through the oil holes
48
.
On the other hand, as shown in
FIG. 1
, the retardation-side oil path
39
leads to an oil groove
50
formed in the upper end portion of the cylinder head
14
and the bearing cap
15
. An oil hole
53
formed in the radially widened portion
11
b
connects the oil groove
50
with an annular oil space
51
formed between the sprocket
17
and the leading end side face of the radially widened portion
11
b
. As shown in
FIGS. 1 and 2
, the sprocket
17
has four oil holes
52
, each of which opens in the vicinity of the side face of a corresponding one of the protruding portions
25
. Each of the oil holes
52
connects the oil space
51
with a corresponding one of the retardation hydraulic chambers
31
. The oil in the oil space
51
is supplied to the hydraulic chambers
31
.
The advancement-side oil path
38
, the oil groove
44
, the oil hole
45
, the oil passage
46
, the annular space
47
and the respective oil holes
48
constitute an advancement hydraulic passage P
1
for supplying oil to the respective advancement hydraulic chambers
30
. On the other hand, the retardation-side oil path
39
, the oil groove
50
, the oil hole
53
, the oil space
51
and the respective oil holes
52
constitute a retardation hydraulic passage P
2
for supplying oil to the respective retardation hydraulic chambers
31
.
The OCV
40
switches a communication state between the advancement hydraulic passage P
1
and the retardation hydraulic passage P
2
on one side and the pump
13
and the oil pan
43
on the other side.
As shown in
FIG. 1
, a casing
54
constituting the OCV
401
has first to fifth ports
55
to
59
. The first port
55
leads to the advancement-side oil path
38
, and the second port
56
leads to the retardation-side oil path
39
. The third and fourth ports
57
and
58
lead to the oil pan
43
, and the fifth port
59
leads to a discharge side of the pump
13
through the oil filter
41
.
A spool
60
, which is reciprocally provided in the casing
54
, has four cylindrical valve bodies
61
. An electromagnetic solenoid
62
moves the spool
60
between a “retardation position” shown in FIG.
1
and an “advancement position” shown in
FIG. 3. A
spring
64
, which is provided in the casing
54
, urges the spool
60
toward the “retardation position”.
The ECU
65
performs duty control for changing a driving mode of the electromagnetic solenoid
62
. That is, the ECU
65
holds the spool
60
at the “advancement position” by driving the electromagnetic solenoid
62
with a duty ratio of 100%. Thus, as shown in
FIG. 3
, the advancement-side oil path
38
is connected to the discharge side of the pump
13
through the first port
55
and the fifth port
59
. The retardation-side oil path
39
is connected to oil pan
43
through the second port
56
and the fourth port
58
. As a result, oil is supplied to the respective advancement hydraulic chambers
30
through the advancement hydraulic passage P
1
, while the oil in the respective retardation hydraulic chambers
31
is returned to the oil pan
43
through the retardation hydraulic passage P
2
.
On the other hand, the ECU
65
holds the spool
60
at the “retardation” position by stopping conduction control for the electromagnetic solenoid
62
(with a duty ratio of 0%). Thus, as shown in
FIG. 1
, the retardation-side oil path
39
is connected to the discharge side of the pump
13
through the second port
56
and the fifth port
59
, while the advancement-side oil path
38
is connected to the oil pan
43
through the first port
55
and the third port
57
. As a result, oil is supplied to the respective retardation hydraulic chambers
31
through the retardation hydraulic passage P
2
, while the oil in the respective advancement hydraulic chambers
30
is returned to the oil pan
43
through the advancement hydraulic pass age P
1
.
Furthermore, the ECU
65
holds the spool
60
at a “holding position” by driving the electromagnetic solenoid
62
with a duty ratio of 50%. At this moment, the valve body
61
of the spool
60
is held at such a position that oil can be homogeneously supplied to the advancement hydraulic passage P
1
and the retardation hydraulic passage P
2
, so as to maintain the pressures in the advancement hydraulic chambers
30
and the retardation hydraulic chambers
31
.
A rotational speed sensor
66
and an intake pressure sensor
67
(FIG.
1
), which are connected to the ECU
65
, detect a rotational speed of the engine and an intake pressure respectively. Likewise, a crank angle sensor
68
and a cam angle sensor
69
, which are connected to the ECU
65
, detect rotational phases of a crank shaft (not shown) and the cam shaft
11
, respectively. Based on detection signals inputted from the respective sensors
66
to
69
, the ECU
65
calculates a target rotational phase (target valve timing) of the cam shaft
11
suited for an operation state of the engine. The ECU
65
also detects an actual rotational phase (actual valve timing) of the cam shaft
11
. The ECU
65
then controls the OCV
40
such that the difference between the actual and target rotational phases of the cam shaft
11
becomes equal to or smaller than a predetermined value.
Then, the operation of the thus-constructed valve timing control apparatus of this embodiment will be described. The following description will focus on the operation regarding engagement and release of the lock pin
33
.
First of all, it will be described how the lock pin
33
engages the lock recess portion
34
. In accordance with the first embodiment, the lock pin
33
engages the lock recess portion
34
when the engine is stopped.
When the engine shifts from an operation state to a stopped state by turning off an ignition switch (not shown), the ECU
65
ensures certain hydraulic pressure by controlling the OCV
40
, with a view to holding the VVT
12
in a controllable stat e for a predetermined length of time. Based on the thus-ensured hydraulic pressure, the ECU
65
surely stops the VVT
12
in a predetermined intermediate phase where the lock pin
33
engages the lock recess portion
34
. The ECU
65
also supplies the motor
70
with the electricity that has been generated by the generation portion
81
during operation of the engine and stored in the storage portion
82
. Thus, as shown in
FIG. 5A
, the lock pin
33
surely engages the lock recess portion
34
in accordance with rotation of the motor
70
. This state is then held until the engine is restarted.
Thus, in this embodiment, the lock pin
33
engages the lock recess portion
34
independently of hydraulic pressure control for controlling the VVT
12
. Therefore, even in a state where the hydraulic pressure is relatively unstable, for example, immediately after stopping the engine, the lock pin
33
can surely engage the lock recess portion
34
. The electric energy required in this process is obtained from the electric power generated in response to rotation of the cam shaft
11
. Consequently, the effective use of energy can be accomplished.
Then, if the hydraulic pump
13
stops and the supply of oil to the engine is stopped, the oil in the retardation hydraulic chambers
31
and the advancement hydraulic chambers
30
is returned to the oil pan. Hence, the pressures in the retardation hydraulic chambers
31
and the advancement hydraulic chambers
30
also fall.
Next, it will be described how the lock pin
33
is released from the lock recess portion
34
. The lock pin
33
is released from the lock recess portion
34
when starting the engine.
When starting the engine that has been stopped for a long time, immediately after turning on the ignition switch, oil has not been supplied to the advancement hydraulic chambers
30
and the retardation hydraulic chambers
31
. Also, at the moment of subsequent cranking of the crank shaft, the advancement hydraulic chambers
30
and the retardation hydraulic chambers
31
have not reached a sufficient level of hydraulic pressure. When the sprocket
17
is turned in accordance with the cranking, the sprocket
17
, the rotor
19
and the cam shaft
11
start rotating such that they are mechanically coupled to one another in the aforementioned predetermined intermediate phase. This is because the lock pin
33
is in engagement with the lock recess portion
34
as described above.
As shown in
FIG. 2
, the cam shaft
11
is locked into they sprocket
17
in a phase that is advanced by, for example, a predetermined phase (angle) α with respect to a phase exhibiting the most delayed valve timing. Thus, unlike a valve timing control apparatus wherein the engine is started at a most retarded position, it is also possible to further retard the valve timing during operation of the engine with respect to the valve timing at the time of engine start. As described above, the predetermined phase α is set such that good startability of the engine can be ensured.
Then, the supply of engine oil to the advancement hydraulic passage P
1
is started in response to operation of the OCV
40
and the hydraulic pump
13
. The oil is supplied to the advancement hydraulic chambers
30
through the advancement hydraulic passage P
1
, so that the advancement hydraulic chambers
30
are maintained at a predetermined hydraulic pressure. After that, oil is also supplied to the retardation hydraulic chambers
31
through the retardation hydraulic passage P
2
in a similar manner. Then, at the timing corresponding to when the predetermined hydraulic pressure is applied to the advancement hydraulic chambers
30
and the retardation hydraulic chambers
31
, the ECU
65
causes the motor
70
to rotate reversely, thereby removing the lock pin
33
from the lock recess portion
34
and storing the lock pin
33
in the accommodation hole
32
. Thus, smooth rotation of the rotor
19
relative to the sprocket
17
is permitted.
FIG. 5B
shows a state where the lock pin
33
has been released from the lock recess portion
34
.
If the pressure in the advancement hydraulic chambers
30
further increases and the pressure in the retardation hydraulic chambers
31
decreases after release of the lock pin
33
, the rotor
19
rotates relative to the sprocket
17
clockwise in
FIG. 2
, based on a difference in pressure between the advancement hydraulic chambers
30
and the retardation hydraulic chambers
31
that are located on opposite sides of the respective vanes
24
. As a result, the rotational phase of the intake-side cam shaft
11
with respect to the crank shaft is advanced, so that the valve timing of the intake valves is advanced.
On the other hand, if the pressure in the retardation hydraulic chambers
31
further increases and the pressure in the advancement hydraulic chambers
30
decreases, the rotor
19
rotates relative to the sprocket
17
counterclockwise in
FIG. 2
, based on a difference in pressure between the advancement hydraulic chambers
30
and the retardation hydraulic chambers
31
that are located on opposite sides of the respective vanes
24
. As a result, the rotational phase of the intake-side cam shaft
11
with respect to the sprocket
17
, namely, with respect to the crank shaft is retarded, so that the valve timing of the intake valves is retarded.
Furthermore, after release of the lock pin
33
, if oil is supplied to the advancement hydraulic chambers
30
and the retardation hydraulic chambers
31
homogeneously due to the control of the OCV
40
, the cam shaft
11
stops rotating relative to the sprocket
17
. As a result, the valve timing of the intake valves is maintained as it is.
As described hitherto, the following effects can be achieved by this embodiment.
In accordance with the first embodiment, the lock pin
33
engages the lock recess portion
34
through control of the motor
70
, which is independent of hydraulic pressure control for controlling the VVT
12
. Therefore, the lock pin
33
can surely engage the lock recess portion
34
even in a state where the hydraulic pressure for controlling the VVT
12
becomes unstable, for example, immediately after stopping the engine. The electric energy required in this process is obtained from the electric power generated in response to rotation of the cam shaft
11
. Consequently, the effective use of energy can be accomplished.
It is also possible to modify the first embodiment as will be described below.
In accordance with the first embodiment, the electric power for driving the motor
70
to move the lock pin
33
is supplied from the power source portion
80
, which is located at the end portion of the cam shaft
11
that is opposite to the side where the VVT
12
is provided. However, such a construction is not obligatory. That is, the power source portion may also be located at the end, portion of the cam shaft
11
on the side where the VVT
12
is provided. Furthermore, the power source portion need not be disposed at the end portion of the cam shaft
11
. The electric power for driving the motor
70
may be supplied from a component outside the engine, such as a battery mounted in the vehicle.
According to the first embodiment, a construction wherein the lock pin
33
is locked into the sprocket
17
is illustrated. However, the present invention is not limited to such a construction. For example, the lock pin
33
may be designed to be locked into the housing cover
20
.
Although an example in which the storage portion
82
is composed of a secondary cell (battery) is illustrated, the storage portion
82
may be composed of, for example, a capacitor or the like.
According to the first embodiment, an example in which the motor
70
electrically drive-controls a locking mechanism (the lock pin
33
) is illustrated. However, the present invention is not limited to such an example. For example, the locking mechanism may be designed to be electrically drive-controlled by an actuator such as a linear solenoid. In addition, it is not necessary that the locking mechanism be electrically drove-controlled. What is important is that the locking mechanism is drive-controlled by a control system separate from the one for controlling the supply of hydraulic chamber
31
(the first and second hydraulic chambers).
A second embodiment of the present invention will now be described with reference to
FIGS. 6
to
8
. The following description will focus on the features that are different from those of the first embodiment. In the first and second embodiments, like members are denoted by like reference numerals, and the description of those members which are commonly employed in both the embodiments will be omitted.
FIG. 6
shows in cross section the structure of a VVT
12
a
, the OCV
40
and the like of a valve timing control apparatus according to the second embodiment of the present invention. Like those shown in
FIG. 1
, the VVT
12
a
, the OCV
40
and the like are provided on the side of the leading end of the intake-side cam shaft
11
.
FIG. 6
is a sectional view taken along line VI—VI in
FIG. 7
, while
FIG. 7
is a sectional view taken along line VII—VII in FIG.
6
.
FIG. 8
schematically shows the structure of the valve timing control apparatus of this embodiment.
As shown in
FIGS. 6
to
8
, the valve timing control apparatus of this embodiment is different from that of the first embodiment in that the VVT
12
a
is provided with an electric stopper
96
.
As in the aforementioned previously employed valve timing control apparatus, the displacement of a lock pin
33
A of this embodiment is hydraulically controlled. That is, a hydraulic chamber
49
, which is surrounded by the outer peripheral wall of the lock pin
33
A and the inner peripheral wall of a through hole
32
, leads to the annular space
47
through one of the oil holes
48
. If the hydraulic pressure in the hydraulic chamber
49
increases after engine start, the lock pin
33
A is disengaged from an engagement hole
34
.
In these respects, this embodiment is different from the first embodiment. The construction and operation relating to the electric stopper
96
will specifically be described hereinafter.
As shown in
FIG. 6
, an accommodation portion
90
for the electric stopper
96
is provided in a front face of the VVT
12
a
(at the left end in FIG.
6
). A through hole
95
is formed in a side wall of the accommodation portion
90
. The through hole
96
has a circular cross section, extends in the axial direction of the cam shaft
11
, and opens to one of the concave portions
26
.
The electric stopper
96
, which is movable within the through hole
95
, is provided in the accommodation portion
90
. The electric stopper
96
has therein an accommodation hole
96
a
in which a spring
97
is provided. The spring
97
urges the electric stopper
96
in such a direction as to project into the corresponding concave portion
26
. As can be seen from
FIG. 7
, because the electric stopper
96
thus projects into the predetermined concave portion
26
, the rotor
19
is kept from moving relative to the housing
16
at a position where the side face of each of the vanes
24
is spaced apart from a corresponding one of the protruding portions
25
by a predetermined phase α on the side of the respective advancement hydraulic chambers
30
. In the valve timing control apparatus of this embodiment, the lock pin
33
A engages the lock recess portion
34
at the aforementioned position. That is, when the lock pin
33
A engages the lock recess portion
34
A, the cam shaft
11
is locked into the sprocket
17
in a phase that is advanced by a predetermined phase (angle) α with respect to a phase realizing the most retarded valve timing.
As shown in
FIG. 6
, an electromagnetic coil
94
for putting the electric stopper
96
into the accommodation portion
90
from the concave portion
26
against an urging force of the spring
97
is provided in the accommodation portion
90
. Also, a storage portion
92
for supplying electricity to the electromagnetic coil
94
and a control portion
93
for charging and discharging the storage portion
92
are provided in the accommodation portion
90
. It is to be noted herein that the storage portion
92
is composed of a capacitor having a capacitance corresponding to the drive of the electric stopper
96
. In this manner, the storage portion
92
is made compact. Furthermore, a rotation portion
91
b
of a generation portion
91
for charging the storage portion
92
is provided in the accommodation portion
90
. A fixed (excitation) portion
91
a
of the generation portion
91
is provided, for example, on a chain cover
98
(FIG.
8
).
The ECU
65
performs control for supplying electricity to the electromagnetic coil
94
from the storage portion
92
. More specifically, upon detecting through the rotational speed sensor
66
that the rotational speed of the engine has reached a predetermined value, the ECU
65
outputs a command signal to the control portion
93
so as to discharge electricity from the storage portion
92
to the electromagnetic coil
94
. At this moment, the electromagnetic coil
94
is excited and operates to displace the electric stopper
96
from the concave portion
26
toward the accommodation portion
90
against an urging force of the spring
97
. Owing to such operation of the electromagnetic coil
94
, the electric stopper
96
is kept from projecting into the concave portion
26
.
On the other hand if the rotational speed of the engine remains below the predetermined value, the ECU
65
stops outputting the discharge command signal to the control portion
93
. Thereby the electromagnetic coil
94
is kept from being excited, and the electric stopper
96
projects again into the concave portion
26
due to the urging force of the spring
97
.
The electric power generated by the generation portion
91
in response to rotation of the cam shaft
11
is supplied to the storage portion
92
, and the control portion
93
performs control for charging the storage portion
92
. At this moment, the electric power supplied to the electromagnetic coil
94
is temporarily stored in the storage portion
92
and therefore stabilized. The power source for driving the electric stopper
96
is provided in the VVT
12
a
, whereby connecting lines and the like can be omitted, which would be necessitated in the case where the power source is provided outside the VVT
12
a.
Next, the operation of the aforementioned construction of this embodiment will be described. As in the first embodiment, the following description will focus on operations relating to engagement and release of the lock pin
33
A.
First of all, it will be described how the lock pin
33
A engages the lock recess portion
34
.
In accordance with the second embodiment, the lock pin
33
A engages the lock recess portion
34
basically in stopping the engine. That is, if the engine is stopped, the supply of oil to the engine is stopped, and the oil in the retardation hydraulic chambers
31
and the advancement hydraulic chambers
30
is returned to the oil pan.
If the oil is returned, the hydraulic pressure applied to the lock pin
33
A drops, and the lock pin
33
A is displaced toward the sprocket
17
due to an urging force of the spring
35
. Furthermore, in thus stopping the engine, based on counterforces generated by the intake valves, the rotor
19
of the VVT
12
a
rotates relative to the sprocket
17
counterclockwise (See FIG.
7
). In response to such relative rotation, one of the vanes
24
a
comes into abutment on the electric stopper
96
, whose side face on the side of the advancement hydraulic chambers
30
projects into the concave portion
26
in response to the stopping of the engine.
At this moment, as described above, the lock pin
33
A faces the lock recess portion
34
, which the lock pin
33
A surely engages due to the urging force of the spring
35
.
Even in the case where the lock pin
33
A has happened to fail to engage the lock recess portion
34
in stopping the engine, for example, because one of the vanes
24
a
abuts on the electric stopper
96
insufficiently, the engagement is ensured the next time the engine is started.
That is, immediately after starting the engine, the respective portions of the VVT
12
a
are not at a sufficient level of hydraulic pressure, and the rotor
19
is pressed toward the retardation side in response to rotation of the sprocket
17
. Hence, the side face of one of the vanes
24
a
that is located on the side of the advancement hydraulic chambers
30
again comes into abutment on the electric stopper
96
, and the lock pin
33
A again comes to a location facing the lock recess portion
34
. At this moment, the lock pin
33
A engages the lock recess portion
34
due to the urging force of the spring
35
. Since the engine is being started, the rotational speed thereof has not reached the aforementioned predetermined value. Therefore, the electric stopper
96
projects into the concave portion
26
owing to the urging force of the spring
97
.
Thus, according to the second embodiment, even if the lock pin
33
A has happened to fail to engage the lock recess portion
34
when the engine is stopped, the engagement is ensured when the engine is started. In other words, the reliability of the lock pin
33
A when engaging the lock recess portion
34
is enhanced.
Next, it will be described how the lock pin
33
A is released from the lock recess portion
34
.
If the engine is started, the oil that has been sucked by the pump
13
into the oil pan
43
is forcibly delivered into the advancement hydraulic passage P
1
through control of the OCV
40
. After the lapse of a predetermined length of time, the hydraulic pressure in the hydraulic chamber
49
that is in communication with the advancement hydraulic passage P
1
increases, and the lock pin
33
A is released from the lock recess portion
34
due to the thus-increased hydraulic pressure. At this moment, the rotational speed of the engine has already reached the predetermined value. The electromagnetic coil
94
is excited and operates to displace the electric stopper
96
from the concave portion
26
toward the accommodation portion
90
.
Thereby the rotor
19
is allowed to rotate relative to the sprocket
17
(the housing
16
) to the maximum possible extent. The intake valves are opened and closed at predetermine valve timings corresponding to the phase of the rotor
19
relative to the sprocket
17
.
As described hitherto, the following effects can be achieved by the second embodiment of the present invention.
In the second embodiment, the electric stopper
96
is provided to regulate a phase relationship between the sprocket
17
(the housing
16
) and the rotor
19
in the predetermined intermediate phase that enables the lock pin
33
to engage the lock recess portion
34
. Therefore, even if the hydraulic pressure for controlling the VVT
12
a
drops, for example, when the engine is stopped, the urging force of the spring
35
ensures that the lock pin
33
A engages the lock recess portion
34
.
Also, in the second embodiment, the electricity stored in the storage portion
92
is supplied to the electromagnetic coil
94
if it is detected that the rotational speed of the engine has reached the predetermined value. Therefore, even if the lock pin
33
A has happened to fail to engage the lock recess portion
34
in stopping the engine, when the engine is still at a low rotational speed immediately after the starting thereof, the electric stopper
96
remains projecting into the concave portion
26
. Thus, another attempt can be made for engagement of the lock pin
33
A with the lock recess portion
34
. In other words, the reliability of the lock pin
33
A when engaging the recess portion
34
is enhanced.
In addition, according to the second embodiment, the power source (the generation portion
91
) for driving the electric stopper
96
is provided in the VVT
12
a
(in front of the housing
16
), and the electric energy required to drive the electric stopper
96
is obtained from the electric power generated in response to rotation of the cam shaft
11
. Consequently, the effective use of energy can be accomplished, and connecting lines and the like can be omitted, which would be necessitated in the case where the power source is not provided in front of the housing
16
. The amount of electric energy required to drive the electric stopper
96
is small. Thus, the electric stopper
96
can be driven with a compact generation portion and with a small amount of electric power.
The electric power supplied to the electromagnetic coil
94
is temporarily stored in the storage portion
92
and therefore stabilized.
It is also possible to modify the second embodiment as will be described below.
In the second embodiment, there is a storage portion
92
composed of a capacitor. However, the storage portion may be an accumulator battery (battery) or the like.
In the second embodiment, there is a power source (the generation portion
91
or the like) for driving the electric stopper
96
provided in the VVT
12
a
(in front of the housing
16
). However, the power source may be provided at an end portion of the cam shaft
11
opposite to a side where the VVT
12
is provided. Alternatively, the power source may be provided outside the engine.
In accordance with the second embodiment, there is a lock pin
33
A hydraulically driven. However, as in the first embodiment, the lock pin may be electrically driven.
A third embodiment of the present invention will now be described with reference to
FIGS. 9 and 10
. The following description will focus on the features that are different from those of the first and second embodiments.
FIG. 9
schematically shows the structure of the third embodiment.
FIG. 10
shows a partial cross section in the vicinity of the lock pin. In the first, second and third embodiments, like members are denoted by like reference numerals, and the description of those members which are commonly employed in these embodiments will be omitted.
In the valve timing control apparatus of the third embodiment, as shown in
FIG. 9
, the VVT
12
b
is composed of a hydraulic passage L
1
for activating the lock pin and a hydraulic passage L
2
for releasing the lock pin. The hydraulic passages L
1
and L
2
are controlled separately from the advancement hydraulic passage P
1
and the retardation hydraulic passage P
2
.
The hydraulic passage L
1
for activating the lock pin connects an oil switching valve (hereinafter referred to as an OSV)
40
A with a spring accommodation hole
33
b
through an oil path
36
and the like formed in the housing cover
20
. The hydraulic passage L
2
for releasing the lock pin connects the OSV
40
A with the lock recess portion
34
through an oil path
37
and the like formed in the sprocket
17
. Like the aforementioned OCV
40
, the OSV
40
A is connected to the hydraulic pump
13
and the like. Based on a command from the ECU
65
, the hydraulic pressure switching control for the hydraulic passages L
1
and L
2
is carried out separately from the control for the advancement hydraulic passage P
1
and the retardation hydraulic passage P
2
.
Next, the operation of the aforementioned construction of the third embodiment will be described. As in the first and second embodiments, the following description will focus on operations relating to engagement and release of the lock pin
33
B.
First of all, it will be described how the lock pin
33
B engages the lock recess portion
34
.
According to the third embodiment, as in the first and second embodiments, the lock pin
33
B engages the lock recess portion
34
basically in stopping the engine. That is, when the engine transitions from an operative state to a nonoperative state after the ignition switch is turned-off, the ECU
65
controls the OCV
40
to ensure a predetermined hydraulic pressure, so that the VVT
12
b
can be controlled for a predetermined length of time. Based on the thus-ensured hydraulic pressure, the ECU
65
surely stops the VVT
12
b
in a predetermined intermediate phase where the lock pin
33
B engages the lock recess portion
34
. At this moment, the ECU
65
further controls the OSV
40
A such that a hydraulic pressure is supplied to the hydraulic passage L
1
for activating the lock pin and that a hydraulic pressure is released from the hydraulic passage L
2
for releasing the lock pin. Thus, the lock pin
33
B surely engages the lock recess portion
34
due to an urging force of the spring
35
as well as a hydraulic pressure supplied to the accommodation hole
33
b
. This state is thereafter maintained by the urging force of the spring
35
until the engine is restarted.
That is, according to the third embodiment, the engagement of the lock pin
33
B with the lock recess portion
34
is carried out independently of the hydraulic pressure control for the advancement hydraulic passage P
1
and the retardation hydraulic passage P
2
. Therefore, even in a state where the hydraulic pressure becomes relatively unstable, for example, immediately after stopping the engine, the lock pin
33
B can surely engage the lock recess portion
34
.
Next, it will be described how the lock pin
33
B is released from the lock recess portion
34
.
If the engine is started, the oil that has been sucked by the pump
13
into the oil pan is forcibly delivered into the OCV
40
and the OSV
40
by means of the pump
13
. After the lapse of a predetermined length of time, the ECU
65
controls the OSV
40
A such that a hydraulic pressure is released from the hydraulic passage L
1
for activating the lock pin and that a hydraulic pressure is supplied to the hydraulic passage L
2
for releasing the lock pin. This, the lock pin
33
B is surely released from the lock recess portion
34
through a hydraulic pressure supplied thereto, against the urging force of the spring
35
. After that, the released state of the lock pin
33
B is maintained as long as the engine is in operation.
On the other hand, the phase of the rotor
19
relative to the sprocket
17
(the housing
16
) is controlled through the OCV
40
, as described above. The intake valves are opened and closed at predetermined valve timings corresponding to the phase of the rotor
19
relative to the sprocket
17
(the housing
16
).
As described hitherto, the following effects can be achieved by the third embodiment.
In accordance with the third embodiment, in order to cause the lock pin
33
B to engage the lock recess portion
34
or to be released therefrom, the hydraulic passage L
1
for activating the lock pin and the hydraulic passage L
2
for releasing the lock pin are provided, which are controlled separately form the advancement hydraulic passage P
1
and the retardation hydraulic pressure P
2
, therefore, even if the hydraulic pressure for controlling the VVT
12
b
becomes unstable, the lock pin
33
B can surely engage the lock recess portion
34
.
In addition, because there is no need to use the hydraulic pressure for controlling the VVT
12
b
in order to operate the lock pin
33
B, the intermediate phase control on the side of the VVT
12
b
can be performed more reliably.
It is also possible to modify the third embodiment as will be described below.
In accordance with the third embodiment, a construction wherein the lock pin
33
B is retained in the lock recess portion
34
by the urging force of the spring
35
until the engine is restarted is illustrated. However, it is possible to dispense with the spring
35
. In this case, in order to ensure that the lock pin
33
B is securely locked, the apparatus may be designed such that the hydraulic pressure in the hydraulic passage L
1
for activating the lock pin can be maintained even after the engine is stopped.
Moreover, the first to third embodiments can also be modified as will be described below.
In the first to third embodiments, the number of the vanes
24
belonging to the rotor
19
may not be more than 3 or may not be less than 5.
In the first to third embodiments, the housing
16
and the rotor
19
are movably fixed to the sprocket
17
and the cam shaft
11
respectively. However, as a different combination, the rotor
19
and the housing
16
may be movably fixed to the sprocket
17
and the cam shaft
11
respectively.
In accordance with the first to third embodiments, shown a construction of the VVT wherein one of the vanes
24
is provided with the lock pin
33
,
33
A or
33
B is illustrated. However, the present invention can also be applied to a construction of the VVT wherein the protruding portion of the housing
16
is provided with a lock pin.
In accordance with the first to third embodiments, an example in which the VVT is provided on the intake-side cam shaft
11
is illustrated. However, the VVT may also be provided on an exhaust-side cam shaft. Alternatively, it Is also possible to provide each of the intake-side and exhaust-side cam shafts with a VVT.
While the present invention has been described with reference to what are presently considered to be preferred embodiments thereof, it is to be understood that the present invention is not limited to the disclosed embodiments or construction. On the contrary, the present invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosed invention are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single embodiment, are also within the spirit and scope of the present invention.
Claims
- 1. A valve timing control apparatus for an internal combustion engine including valves and an output shaft, comprising:a rotational body drivingly coupled to the output shaft of the internal combustion engine; a cam shaft configured to drivingly open and drivingly close the valves of the internal combustion engine; a hydraulic chamber configured to change a rotational phase between the output shaft and the cam shaft through supply of a hydraulic pressure, the hydraulic chamber being formed between the rotational body and the cam shaft; a first hydraulic pressure control system configured to control the hydraulic pressure supplied to the hydraulic chamber; a lock mechanism configured to maintain the rotational phase between the output shaft and the cam shaft in a predetermined intermediate phase through a force other than the hydraulic pressure; a lock mechanism control system configured to drivingly control the lock mechanism; and a second hydraulic pressure control system provided separately from the first hydraulic pressure control system, wherein the lock mechanism control system is configured to drive-control the lock mechanism through the second hydraulic pressure control system such that rotational movement between the output shaft and the cam shaft in a predetermined intermediate phase can be prevented with a second supply of hydraulic pressure supplied through the second hydraulic pressure control system.
- 2. The valve timing control apparatus according to claim 1, wherein the lock mechanism includes a lock pin projecting from one of the rotational body and the cam shaft and a lock recess portion formed in the other of the rotational body and the cam shaft for engagement of the lock pin, and wherein the lock mechanism control system controls projection and non-projection of the lock pin.
- 3. The valve timing control apparatus according to claim 1, wherein the hydraulic chamber includes first and second hydraulic chambers, and wherein the rotational phase between the output shaft and the cam shaft is changed by changing a ratio of hydraulic pressure in the first and second hydraulic chambers.
- 4. The valve timing control apparatus according to claim 1, wherein the second hydraulic pressure control system includes a lock activating hydraulic passage configured to activate the lock mechanism and a lock releasing hydraulic passage configured to release the lock mechanism.
- 5. A valve timing control apparatus for an internal combustion engine including valves and an output shaft, comprising:a rotational body drivingly coupled to the output shaft of the internal combustion engine; a cam shaft configured to drivingly open and drivingly close the valves of the internal combustion engine; a first hydraulic chamber configured to change a rotational phase between the output shaft and the cam shaft through supply of a first hydraulic pressure, the first hydraulic chamber being formed between the rotational body and the cam shaft; a first hydraulic pressure control system configured to control the hydraulic pressure supplied to the first hydraulic chamber; a lock mechanism configured to maintain the rotational phase between the output shaft and the cam shaft in a predetermined intermediate phase through supply of a second hydraulic pressure to a second hydraulic chamber, which is provided in the lock mechanism; and a second hydraulic pressure control system configured to control the second hydraulic pressure supplied to the second hydraulic chamber, wherein the second hydraulic pressure control system includes a lock activating hydraulic passage configured to supply the second hydraulic pressure to activate the lock mechanism and a lock releasing hydraulic passage configured to supply the second hydraulic pressure to release the lock mechanism.
- 6. The valve timing control apparatus according to claim 5, wherein the lock mechanism includes a lock pin projecting from one of the rotational body and the cam shaft and a lock recess portion formed in the other of the rotational body and the cam shaft for engagement of the lock pin, and wherein the second hydraulic pressure control system controls projection and non-projection of the lock pin.
- 7. The valve timing control apparatus according to claim 5, wherein the first hydraulic chamber includes at least two hydraulic chambers, and wherein the rotational phase between the output shaft and the cam shaft is changed by changing a ratio of hydraulic pressure in the at least two hydraulic chambers.
- 8. The valve timing control apparatus according to claim 7, wherein the at least two hydraulic chambers comprise an advancement hydraulic chamber and a retardation hydraulic chamber.
- 9. The valve timing control apparatus according to claim 5, wherein the second hydraulic pressure control system is provided separately from the first hydraulic pressure control system, and the second hydraulic pressure control system is configured to drive-control the lock mechanism.
- 10. A valve timing control apparatus for an interns combustion engine including valves and an output shaft, comprising:a rotational body drivingly coupled to the output shaft of the internal combustion engine; a cam shaft configured to drivingly open and drivingly close the valves of the internal combustion engine; a first hydraulic chamber configured to change a rotational phase between the output shaft and the cam shaft through supply of a first hydraulic pressure; a first hydraulic pressure control system configured to control the hydraulic pressure supplied to the first hydraulic chamber; a second hydraulic chamber provided separately from the first hydraulic chamber; a lock mechanism configured to maintain the rotational phase between the output shaft and the cam shaft in a predetermined intermediate phase through supply of a second hydraulic pressure to the second hydraulic chamber, the second hydraulic chamber being provided in the lock mechanism; and a second hydraulic pressure control system configured to control the second hydraulic pressure supplied to the second hydraulic chamber such that the rotational phase between the output shaft and the cam shaft can be maintained in or released from a predetermined intermediate phase, wherein the second hydraulic pressure control system is controlled separately from the first hydraulic pressure control system.
- 11. The valve timing control apparatus according to claim 10, wherein the lock mechanism includes a lock pin projecting from one of the rotational body and the cam shaft and a lock recess portion formed in the other of the rotational body and the cam shaft for engagement of the lock pin, and wherein the second hydraulic pressure control system controls projection and non-projection of the lock pin.
- 12. The valve timing control apparatus according to claim 10, wherein the first hydraulic chamber includes at least two hydraulic chambers, and wherein the rotational phase between the output shaft and the cam shaft is changed by changing a ratio of hydraulic pressure in the at least two hydraulic chambers.
- 13. The valve timing control apparatus according to claim 12, wherein the at least two hydraulic chambers comprise an advancement hydraulic chamber and a retardation hydraulic chamber.
- 14. The valve timing control apparatus according to claim 10, wherein the second hydraulic pressure control system is configured to drive-control the lock mechanism.
- 15. The valve timing control apparatus according to claim 10, wherein the second hydraulic pressure control system includes a lock activating hydraulic passage configured to activate the lock mechanism and a lock releasing hydraulic passage configured to release the lock mechanism.
Priority Claims (1)
Number |
Date |
Country |
Kind |
10-347198 |
Dec 1998 |
JP |
|
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
5901674 |
Fujiwaki |
May 1999 |
A |
5941202 |
Jung |
Aug 1999 |
A |
6089198 |
Goppelt et al. |
Jul 2000 |
A |
Foreign Referenced Citations (4)
Number |
Date |
Country |
19914767 |
Oct 1999 |
DE |
4-140407 |
May 1992 |
JP |
7-189621 |
Jul 1995 |
JP |
9-324613 |
Dec 1997 |
JP |