U.S. patent application number 09/791870 was filed with the patent office on 2001-08-09 for lock mechanism for valve timing regulation device.
Invention is credited to Sekiya, Mutsuo, Sugawara, Masafumi.
Application Number | 20010011534 09/791870 |
Document ID | / |
Family ID | 14236077 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010011534 |
Kind Code |
A1 |
Sugawara, Masafumi ; et
al. |
August 9, 2001 |
Lock mechanism for valve timing regulation device
Abstract
The present invention relates to a lock mechanism for a valve
timing regulation device which regulates the timing of the opening
and closing of engine valves, the lock mechanism locks or releases
a first rotating body and a second rotating body in response to the
operational condition of an engine. The lock mechanism includes a
radial groove 32 provided in either the first rotating body 21 or
the second rotating body 24 and extending in a radial direction of
the rotating body. A locking member 35 is slidably inserted into
the radial groove 32, and the locking member is urged towards a
center of the rotating body by an urging means 36. An oil pressure
is applied to the locking member 35 in a direction opposite to the
urging direction. In such a way, it is possible to assemble the
locking member 35 onto an end face in an axial direction other than
a vane 24a or a shoe 23a in either the first rotating body or the
second rotating body, as a result, each vane 24a or each shoe 23a
can be formed with approximately the same circumferential length.
Thus, it is possible to expand the angular range to be regulated by
the valve timing regulation device and to reduce the degree of
unbalance in the device by a large amount.
Inventors: |
Sugawara, Masafumi; (Tokyo,
JP) ; Sekiya, Mutsuo; (Tokyo, JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS, PLLC
2100 Pennsylvania Avneu N.W.
Washington
DC
20037-3213
US
|
Family ID: |
14236077 |
Appl. No.: |
09/791870 |
Filed: |
February 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09791870 |
Feb 26, 2001 |
|
|
|
PCT/JP99/03431 |
Jun 25, 1999 |
|
|
|
Current U.S.
Class: |
123/90.16 ;
123/90.15 |
Current CPC
Class: |
Y10T 74/2102 20150115;
F01L 2001/34453 20130101; F01L 1/3442 20130101 |
Class at
Publication: |
123/90.16 ;
123/90.15 |
International
Class: |
F01L 001/34 |
Claims
What is claimed is:
1. A lock mechanism for a valve timing regulation device which
performs locking to enable synchronous rotation of a first rotating
body and a second rotating body and releases the locking to enable
relative rotation of the first rotating body and the second
rotating body, said first and said second rotating bodies being
provided on a rotation shaft for opening and closing engine valves,
said lock mechanism comprising: an engaging projection disposed on
an end face in an axial direction of one of the first rotating body
and the second rotating body; a radial groove disposed on an end
face in an axial direction of the other of the first rotating body
and the second rotating body which faces said one of the first
rotating body and the second rotating body, said radial groove
extending in a radial direction of said rotating body; a
circumferential groove extending in a circumferential direction of
said rotating body from said radial groove, said circumferential
groove being engaged with said engaging projection to allowing
sliding of said engaging projection; a locking member which is
stored in said radial groove to slide in the radial direction of
said rotating body; a guide groove formed on said locking member
and selectively communicated with said circumferential groove; an
urging means for urging said locking member towards a center of
said rotating body from a position in which said guide groove
communicates with said circumferential groove; and an oil pressure
supply means for applying an oil pressure to said locking member in
a direction resisting said urging means.
2. The lock mechanism according to claim 1, wherein said
circumferential groove extends in the circumferential direction of
said rotating body from both sides of said radial groove and is
divided longitudinally by said radial groove, and wherein a groove
width of said guide groove gradually increases towards one of said
divided circumferential grooves.
3. The lock mechanism according to claim 1, wherein said locking
member is formed to be rectangular in cross section and said radial
groove storing the locking member is formed with a cross sectional
shape which is adjusted so that said locking member can slide
therein.
4. The lock mechanism according to claim 1, wherein a plate
covering said radial groove and said circumferential groove is
interposed between said first rotating body and said second
rotating body.
5. The lock mechanism according to claim 4, wherein said plate is
provided with a common oil pressure passage which communicates with
each of an advancing oil pressure chamber and a retarding oil
pressure chamber, and said oil pressure passage is provided with an
oil passage switching valve for switching an oil pressure applying
passage to said locking member between said advancing oil pressure
chamber and said retarding oil pressure chamber.
6. The lock mechanism according to claim 4, wherein engaging
projections are provided on both surfaces of said plate, said
engaging projection on one surface of said plate engaging with said
guide groove and said circumferential groove, said engaging
projection on the other surface of said plate being fitted into an
engagement hole provided in the rotating body which does not have
the radial groove and the circumferential groove, and wherein said
plate is adapted to rotate together with said rotating body and to
rotate relatively to the other rotating body.
7. The lock mechanism according to claim 6, wherein said engaging
projections are formed by a single engaging member which passes
through said plate.
Description
CROSS-REFERENCE TO THE RELATED APPLICATION
[0001] This application is a continuation of international
Application No. PCT/JP99/03431, whose international filing date is
Jun. 25, 1999, the disclosures of which Application are
incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a lock mechanism for a
valve timing regulation device which varies the opening and closing
timing of one or both of an intake valve and an exhaust valve by an
actuator in accordance with an operational condition of an
engine.
[0004] 2. Description of Related Art
[0005] A lock mechanism for a valve timing regulation device is
known which is provided with a rotor and a housing able to rotate
relative to a camshaft which opens and closes a valve of an engine
system. The rotor and housing are synchronously rotated by locking
them in response to engine operating conditions and are relatively
rotated by releasing the lock.
[0006] FIG. 1 is a cross sectional view along an axial direction
showing a lock mechanism for a valve timing regulation device in a
first conventional example as disclosed for example in
JP-A-9-280018. In the figure, reference numeral 1 denotes a
camshaft which drives the opening and closing of a valve in an
engine system and 2 is a timing pulley which is rotatably attached
on the camshaft 1. A rotational driving force is transmitted from a
crank shaft (not shown) of the engine to the timing pulley 2. 3 is
a housing which is fixed to rotate integrally with respect to the
timing pulley 2. 4 is a rotor which is linked to a tip of the
camshaft 1 and which is stored in the housing 3. The rotor 4 has a
plurality of vanes 4a which extend in a radial direction and
slidably abut with a side of the timing pulley 2 and an inner
peripheral surface of the housing 3. The rotor 4 can rotate
relatively to the housing 3. 5 is a cover which covers the open end
of the housing 3. 6 is a through hole which is provided on one vane
4a of the rotor 4 and which extends in an axial direction of the
camshaft 1. 7 is a locking hole which is provided on the timing
pulley 2 and which is communicated with the through hole 6. 8 is a
lock pin which is slidably inserted in the through hole. The lock
pin 8 is urged by a spring 9 and is inserted into the locking hole
7. The housing 3 and the rotor 4 are locked by the insertion of the
lock pin 8 into the locking hole 7, thereby to prevent the relative
rotation of them. 10a is an oil passage which is connected to the
locking hole 7, 10b is an oil passage which is connected to the
large diameter hole 6a of the through hole 6. The oil passages 10a,
10b are connected to an oil pressure supply means (oil pump)
through an oil control valve (not shown). When an oil pressure
supplied to the large diameter hole 6a of the through hole 6 and
the locking hole 7 from each oil passage 10a, 10b increases to
above a predetermined value, the locking pin 8 releases the lock of
the rotor 4 and the housing 3 by retracting from the locking hole 7
by the oil pressure against the urging force of the spring 9.
[0007] The operation of the first conventional lock mechanism for a
valve timing regulation device will be discussed below.
[0008] When the engine is stopped, the oil pressure applied to the
locking pin 8 is not more than the predetermined value, the locking
pin 8 on the rotor side is engaged with the locking hole 7 of the
timing pulley 2 by the urging force of the spring 9. Thus, the
rotor 4 and the housing 3 integrated with the timing pulley 2 are
in a locked state. After this state, when the oil pressure supplied
to the large diameter section 6a of the through hole 6 and the
locking hole 7 through the oil passage 10a, 10b exceeds the
predetermined value by the activation of the oil pump due to engine
startup, the locking pin 8 retracts from the locking hole 7 by the
oil pressure resisting the urging force of the spring 9. In this
way, the lock of the rotor 4 and the housing 3 is released and
these components can undergo relative rotation. As a result of this
relative rotation, the opening and closing timing of the valve is
regulated.
[0009] Since the first conventional lock mechanism for a valve
timing regulation device is constructed above, it is necessary to
store a locking pin 8 in the vane 4a (through hole 6) of the rotor
4 to slide along the axial direction of the camshaft 1. The vane 4a
storing the locking pin 8 must be formed to be longer in the
circumferential direction in comparison with other vanes which do
not store the locking pin 8. When the length in the circumferential
direction is lengthened, not only is the regulated angular range of
the valve timing regulation device reduced, but also the balance
with respect to the center of rotation of the rotor 4 is lost.
Thus, problems with respect to mechanical strength and the
generation of vibrations have arisen.
[0010] FIG. 2 is a cross sectional view in the radial direction of
a lock mechanism for a valve timing regulation device according to
a second conventional example as disclosed for example in
JP-A-9-303118. Those components which are the same or similar to
components in FIG. 1 are denoted by the same reference numerals and
further discussion will be omitted. In FIG. 2, reference numerals
3a, 3b are shoes which protrude from the inner peripheral surface
of the housing 3. Of the shoes 3a, 3b, one shoe 3a is formed to be
longer in the circumferential direction than the other shoe 3b in
order to store the lock mechanism. 11 is a pin hole which is
provided on the shoe 3a and extends in a radial direction of the
housing 3. 12 is a locking pin which is inserted slidably in the
pin hole 11. 13 is a spring which urges the locking pin 12 in a
direction of the rotor 4. 14 is a locking hole provided on the
rotor 4. The locking hole 14 is connectable with the pin hole 11.
15 is an oil passage which is connected with the locking hole 14.
An oil pressure from the oil pressure control system is supplied to
the oil passage 15.
[0011] The operation of the second conventional lock mechanism for
a valve timing regulation device will be discussed below.
[0012] The locking pin 12 on the housing 3 side is inserted into
the locking hole 14 of the rotor 4 by the urging force of the
spring 13, the housing 3 and the rotor 4 are locked to rotate
synchronously. When the oil pressure supplied to the oil passage 15
in response to an operational condition of the engine exceeds a
predetermined value, the locking pin 12 is displaced towards an
outer peripheral surface of the housing 3 by the oil pressure
against the urging force of the spring 13 and the locking pin 12
retracts from the locking hole 14. In such a way, in the same way
as the first conventional example, the locking of the rotor 4 and
the housing 3 is released and both components are retained in a
state allowing relative rotation.
[0013] Since the second conventional lock mechanism for a valve
timing regulation device is constructed above, of the shoes 3a, 3b
of the housing 3, it is required to make the shoe 3a which acts as
storage for the lock mechanism to be longer in the circumferential
direction than the other shoe 3b. When the length in the
circumferential direction is lengthened, in the same way as the
first conventional example, not only is the regulated angular range
of the valve timing regulation device reduced, but also the balance
with respect to the center of rotation of the rotor 4 is lost.
Thus, problems with respect to mechanical strength and the
generation of vibrations have arisen.
SUMMARY OF THE INVENTION
[0014] The present invention is proposed to solve the above
problems and has the object of providing a lock mechanism for a
valve timing regulation device in which a plurality of shoes
provided on the housing and a plurality of vanes provided on the
rotor have approximately the same length in the circumferential
direction. The lock mechanism of the present invention enables the
enlargement of the angular range to be regulated by the valve
timing regulation device and allows great reductions in the degree
of unbalance with respect to the rotational center. Furthermore,
problems with respect to mechanical strength and the generation of
vibrations are avoided.
[0015] The present invention has the further object of providing a
lock mechanism for a valve timing regulation device which can
accurately and smoothly perform locking and unlocking
operations.
[0016] The present invention has the further object of providing a
lock mechanism for a valve timing regulation device which can
improve productivity by the ease molding by sintering or the like
and which thus enables reduction in manufacturing costs.
[0017] The present invention has the further object of providing a
lock mechanism for a valve timing regulation device which enables
improvement of the operation of the locking member.
[0018] The present invention has the further object of providing a
lock mechanism for a valve timing regulation device which enables
the application of an oil pressure to a locking member in both an
advancing and retarding direction of the rotating body and which
can retain or release normal locking when the oil pressure is not
less than a predetermined value.
[0019] The present invention has the further object of providing a
lock mechanism for a valve timing regulation device in which a
function of mounting it on one of the first and second rotating
bodies and a function of slidable engagement with the other of the
first and second rotating bodies can be achieved by a single
component.
[0020] The present invention has the further object of providing a
lock mechanism for a valve timing regulation device which can
improve mass production efficiency by the simplification of
component structure.
[0021] According to the present invention, there is provided a lock
mechanism for a valve timing regulation device which performs
locking to enable synchronous rotation of a first rotating body and
a second rotating body and releases the locking to enable relative
rotation of the first rotating body and the second rotating body,
the first and second rotating bodies being provided on a rotation
shaft for opening and closing engine valves, the lock mechanism
comprising: an engaging projection disposed on an axial end face of
one of the first rotating body and the second rotating body; a
radial groove disposed on an axial end face of the other of the
first rotating body and the second rotating body which faces the
one of the first rotating body and the second rotating body, the
radial groove extending in a radial direction of the rotating body;
a circumferential groove extending in a circumferential direction
of the rotating body from the radial groove, the circumferential
groove being engaged with the engaging projection to allowing
sliding of the engaging projection; a locking member which is
stored in the radial groove to slide in the radial direction of the
rotating body; a guide groove formed on the locking member and
selectively communicated with the circumferential groove; an urging
means for urging the locking member towards a center of the
rotating body from a position in which the guide groove
communicates with the circumferential groove; and an oil pressure
supply means for applying an oil pressure to the locking member in
a direction resisting the urging means.
[0022] This type of lock mechanism for a valve timing regulation
device has an engaging projection provided on an axial end face of
one of the first and second rotating bodies, a radial groove
provided on an axial end face of the other of the first and second
rotating bodies, and a locking member slidably inserted in the
radial groove. Therefore, the formation region of the radial groove
on the rotating body can be formed with sufficient mechanical
strength by the locking member which is fit into the radial groove.
As a result, it is not necessary to lengthen the shoe or the vane
storing the locking member so as to be longer in the
circumferential direction than other vanes or shoes not storing the
locking member. Thus, it is possible to form each vane or each shoe
with approximately the same length in the circumferential
direction. As a result, the angular range regulated by the valve
timing regulation device can be enlarged and it is possible to
eliminate the problems such as mechanical strength and the
generation of vibration by large reductions in the degree of
unbalance with respect to the rotational center of the rotating
body. Furthermore, when the oil pressure of the oil pressure
control system provided in the valve timing regulation device is
not more than a predetermined value, the first rotating body and
the second rotating body can be rotated synchronously by the
locking member locking the engaging projection by the urging means.
When the oil pressure of the oil pressure control system becomes
more than the predetermined value, the locking of the engaging
projection by the locking member is released by the displacement of
the locking member due to the oil pressure resisting the urging
means and thus the first and second rotating bodies can rotate
relatively to one another. Therefore, it is possible to accurately
and smoothly perform both synchronous and relative rotations of the
first and second rotating bodies in response to the variation in
the oil pressure of the oil pressure control system.
[0023] In the lock mechanism for the valve timing regulation device
according to the present invention, the circumferential groove may
be adapted to extend in a circumferential direction of the rotating
body from both sides of the radial groove and to be divided
circumferentially by the radial groove. In such a structure, the
groove width of the guide groove gradually increases towards one of
the divided circumferential grooves.
[0024] The lock mechanism for a valve timing regulation device such
as the above allows the rapid introduction of the engaging
projection, which is not aligned with the guide groove, into the
guide groove of the locking member at a time when the locking
member is slightly displaced by the oil pressure in a direction
which resists the urging means. When the locking member is
displaced in the direction resisting the urging means, it is
possible to improve the response characteristics of the engaging
projection which is not aligned with the guide groove. Further,
when the second rotating body is positioned on an advancing side
and the engaging projection is not aligned with the guide groove,
an oil pressure which can resist the urging force of the urging
means may be reduced below the predetermined value. Even in such a
case, the second rotating body tends to displace in a retarding
direction by the reaction torque of the camshaft, the engaging
projection slides on the side wall of the guide groove. As a
result, the engaging projection displaces the locking member
mechanically in a radial direction towards an outer periphery of
the rotating body against the urging force of the urging means.
Therefore, even when no oil pressure exists, the locking member can
be surely retained in a lock released state up to a position of
maximum retardation of the second rotating body.
[0025] In the lock mechanism for the valve timing regulation device
according to the present invention, the locking member may be
formed to be rectangular in cross section, and the radial groove
storing the locking member may be formed with a cross sectional
shape which is adjusted so that the locking member can slide
therein.
[0026] According to the lock mechanism for the valve timing
regulation device such as the above, it is possible to increase
ease of manufacture of dies for molding and die formation of the
locking member by sintering metal or the like, productivity can be
improved, and costs can be reduced.
[0027] In the lock mechanism for the valve timing regulation device
according to the present invention, a plate covering the radial
groove and the circumferential groove may be interposed between the
first rotating body and the second rotating body.
[0028] In the lock mechanism for the valve timing regulation
device, since the circumferential groove and the exposed surface of
the locking member inserted into the radial groove are covered by
the plate, it is possible to prevent the advancing/retarding oil
chamber provided in the valve timing regulation device from being
communicated with the radial groove and the circumferential groove.
Furthermore, the sliding of the locking member is improved.
[0029] In the lock mechanism for the valve timing regulation device
according to the present invention, the plate may be provided with
a common oil pressure passage which communicates with each of an
advancing oil pressure chamber and a retarding oil pressure
chamber, the oil pressure passage may be provided with an oil
passage switching valve for switching an oil pressure applying
passage to the locking member between the advancing oil pressure
chamber and the retarding oil pressure chamber.
[0030] This type of lock mechanism for the valve timing regulation
device allows selective application of an oil pressure to the
locking member from either the advancing oil pressure chamber or
the retarding oil pressure chamber. Thus, it is possible to
maintain a lock released state of the first rotating body and the
second rotating body as long as the applied oil pressure is not
less than a predetermined value.
[0031] In the lock mechanism for the valve timing regulation device
according to the present invention, engaging projections may be
provided on both surfaces of the plate. The engaging projection on
one face of the plate engages with the guide groove and the
circumferential groove. The engaging projection on the other face
of the plate is fitted into an engagement hole provided in the
rotating body which does not have the radial groove and the
circumferential groove. Further, the plate is adapted to rotate
together with the rotating body and to rotate relatively to the
other rotating body.
[0032] In the lock mechanism for the valve timing regulation
device, of the engaging projections which are provided on both
sides of the plate, the engaging projection other than that engaged
with the guide groove and the circumferential groove is engaged
with the engagement hole of the rotating body. Thus, it is possible
to rotate the plate together with the rotating body with only this
mechanism. Namely, it is possible to assemble both components
simply.
[0033] In the lock mechanism for the valve timing regulation device
according to the present invention, the engaging projections may be
formed by a single engaging member which passes through the
plate.
[0034] In the lock mechanism for the valve timing regulation
device, it is not necessary to provide an engaging projection for
fixing the plate on one rotating body as a separate member from an
engaging projection which is engaged with the circumferential
groove and the guide groove provided in the other rotating body. As
a result, the structure of the unit including the engaging
projection and the plate can be simplified by the reduction in the
number of components, costs can be reduced and productivity can
also be increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a cross sectional view in the axial direction of a
lock mechanism for a valve timing regulation device according to a
first conventional example.
[0036] FIG. 2 is a cross sectional view in the radial direction of
a lock mechanism for a valve timing regulation device according to
a second conventional example.
[0037] FIG. 3 is a cross sectional view in the radial direction of
a lock mechanism for a valve timing regulation device according to
a first embodiment of the present invention.
[0038] FIG. 4 is a cross sectional view along the line A-A in FIG.
3.
[0039] FIG. 5 is an exploded perspective view of a lock mechanism
for a valve timing regulation device according to the first
embodiment of the present invention.
[0040] FIG. 6(a) to FIG. 6(d) are explanatory views describing the
operation of the present invention.
[0041] FIG. 7 is a cross sectional view of a lock mechanism for a
valve timing regulation device according to a second embodiment of
the present invention.
[0042] FIG. 8 is a plan view showing a plate of a valve timing
regulation device according to a third embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] In order to describe the invention in greater detail, the
preferred embodiments will be outlined below with reference to the
accompanying figures.
[0044] Embodiment 1
[0045] FIG. 3 is a cross sectional view in the radial direction of
a lock mechanism for a valve timing regulating device according to
a first embodiment of the present invention. FIG. 4 is a cross
sectional view along the line A-A in FIG. 3. In the figures,
reference numeral 21 denotes a first rotating body which is
provided on a camshaft for driving the opening and dosing of the
valves of an engine. The first rotating body 21 includes a first
housing 22 rotatably mounted on the camshaft and a second housing
23 fixed to the first housing 22.
[0046] 24 is a second rotating body (rotor) which is linked to the
camshaft and stored in the second housing 23. The second rotating
body 24 is comprised by a rotor which can rotate relatively to the
first rotating body 21. 23a denotes a plurality of shoes which are
disposed at fixed intervals on the inner peripheral surface of the
second housing 23 so as to protrude from the inner peripheral
surface of the second housing 23. The tips of the shoes 23a
slidably abut with a body portion of the second rotating body 24.
24a denotes a plurality of vanes which are arranged on the body
portion of the second rotating body 24 and extend in a radial
direction from the body portion of the second rotating body 24. The
tips of the vanes 24a slidably abut with the inner peripheral
surface of the second housing 23. 25 is an advancing oil pressure
chamber which rotates each vane 24a in an advancing direction. 26
is an retarding oil pressure chamber which rotates each vane 24a in
a retarding direction. The advancing oil pressure chamber 25 and
the retarding oil pressure chamber 26 are formed in a fan shape
between each shoe 23a and each vane 24a and between the second
housing 23 and the second rotating body 24.
[0047] 30 is a lock mechanism which locks the first rotating body
21 and the second rotating body 24 to enable synchronous rotation
of the first rotating body 21 and the second rotating body 24 and
which allows relative rotation of the first rotating body 21 and
the second rotating body 24 by releasing the lock.
[0048] FIG. 5 is an exploded perspective view of a lock mechanism
for a valve timing regulation device according to the first
embodiment of the present invention. The lock mechanism as shown in
FIG. 5 is shown from a vertical direction opposite to the lock
mechanism 30 as shown in FIG. 3 and FIG. 4 but has the same
structure. In FIG. 5, 31 denotes a concave portion which is formed
on an end face in an axial direction of the second housing 23 and
which opens towards an end face in the axial direction of the
second rotating body 24. 32 is a radial groove for storage of the
locking member which is formed on the bottom face of the concave
portion 31 and extends in a radial direction of the housing 23. 33a
is a drain hole which communicates with the radial groove 32 and
opens on an outer peripheral surface of the housing 23. 34a, 34b
are circumferential grooves which branch from both sides of the
radial groove 32 and extend in a circumferential direction of the
housing 23. The circumferential grooves 34a, 34b are separated
longitudinally by the radial groove 32. One circumferential groove
34a extends in an advancing direction and the other circumferential
groove 34b extends in a retarding direction. 35 is a locking member
which is fitted into the radial groove 32. The locking member 35
can slide in the radial direction of the first rotating body 21
within the radial groove 32. The locking member 35 has a
quadrangular cross section, and the radial groove 32 which stores
the locking member 35 has a cross section (squared groove shape)
adapted to the locking member 35. 35a is a guide groove which is
formed in approximately a central section of the locking member 35.
The guide groove 35a can communicate mutually with the
circumferential grooves 34a, 34b. After communicating, the lock
engaging projection 38a (discussed below) can be guided in a
direction from one circumferential groove 34a to the other
circumferential groove 34b or in the opposite direction. The guide
groove 35a is formed to gradually enlarge towards one of the
circumferential grooves 34a. In this way, the displacement of the
lock engaging projection 38a from the one of the circumferential
grooves 34a is facilitated. 35b is a pressure receiving portion
having a concave shape, which is provided on an end portion of the
first rotating body 21 towards a rotational center in the locking
member 35. 36 is a spring acting as an urging means which urges the
locking member 35 towards the rotational center of the first
rotational body 21. In the urged position of the locking member 35
due to the spring 36, the guide groove 35a of the locking member 35
does not align with the circumferential groove 34a, 34b so that the
lock engaging projection 38a can not pass through the guide groove
35a.
[0049] 37 is a plate which is fitted into the concave portion 31 of
the second housing 23. The plate 37 covers the guide groove 35a of
the locking member 35, the circumferential groove 34a, 34b and the
radial groove 32. 38 is an engaging projection which is provided on
the plate 37. The engaging projection 38 is composed of a single
engaging member (for example a single pin member) which is fixed
through the plate 37. The engaging projection 38 has a lock
engaging projection portion 38a which projects from one side of the
plate 37 towards the second housing 23 and a mounting engaging
projection portion 38b which projects towards the second rotating
body 24 from the other side of the plate 37 in order to fix the
plate 37 to the second rotating body 24. The lock engaging
projection portion 38a is attached to slide with respect to the
circumferential grooves 34a, 34b and the guide groove 35a and is
locked by the locking member 35.
[0050] 39 is an oil pressure passage which is provided in the plate
37. The oil pressure passage 39 acts as an oil pressure supply
means for supplying an oil pressure to the pressure receiving
portion 35b of the locking member 35. The oil pressure passage 39
has an advancing chamber communication passage 39a which
communicates with the advancing oil pressure chamber 25 and an
retarding chamber communication passage 39b which communicates with
the retarding oil pressure chamber 26. 40 is an oil passage
switching valve which is provided in the oil pressure passage 39.
The oil passage switching valve 40 selectively switches an oil
pressure applying passage for applying an oil pressure to the
pressure receiving portion 35b of the locking member 35 between
either the advancing chamber communication passage 39a or the
retarding chamber communication passage 39b.
[0051] 41 is an engaging protrusion which is integrated with the
plate 37 and is disposed at a position apart from the mounting
engaging projection portion 38b. 42 is an engaging concave portion
which is provided on a vane 24a of the second rotating body 24 so
as to face with the engaging protrusion 41. 43 is an engagement
hole which is provided on the vane 24a so as to face with the
mounting engaging projection portion 38b. The mounting engaging
projection portion 38b is fitted in the engagement hole 43 and the
plate 37 is mounted and fixed to the axial direction end face of
the second rotating body 24 by the engagement of the engaging
protrusion 41 and the engaging concave portion 42. Thus, the plate
37 is inserted into the concave portion 31 of the housing 23 in
this state. The plate 37 inserted into the concave portion 31 can
be displaced in the circumferential direction of the housing 23 by
a fixed distance. That is to say, when the plate 37 is inserted
into the concave portion 31, a gap with a distance of a is
generated between the wall face in the circumferential direction of
the concave portion 31 and the end face in the circumferential
direction of the plate 37 as shown by the broken line in FIG. 5.
The plate can be displaced in the circumferential direction within
the concave portion 31 by the distance a.
[0052] In FIG. 3 and FIG. 4, 33 is an oil pressure supply hole
which is provided in an inner peripheral portion of the housing 22.
The oil pressure supply hole 33 is connected to the radial groove
32 on the opposite side of the drain hole 33a and acts as an oil
pressure supply means which applies the oil pressure to the locking
member 35 in a direction resisting the urging force of the spring
36. The oil pressure supply hole 33 is selectively connected with
the advancing oil pressure chamber 25 and the retarding oil
pressure chamber 26 through the oil pressure passage 39 of the
plate 37 by the oil passage switching valve 40.
[0053] Next, the operation of a lock mechanism for a valve timing
regulation device according to the first embodiment of the present
invention will be described below.
[0054] When the oil pressure applied to the locking member 35 from
the oil pressure supply hole 33 is not more than a predetermined
value, the locking member 35 is maintained by the urging force of
the spring 36 in a position obstructing the communication between
the right and left circumferential grooves 34a, 34b. Thus, when the
lock engaging projection portion 38a is positioned in the
circumferential groove 34b situated on an retarding side, namely,
in a maximum retarding position, the lock engaging projection
portion 38a is maintained in a locked position by the locking
member 35 as shown in FIG. 3 and the first and second rotating
bodies 21, 24 rotate synchronously.
[0055] When the oil pressure becomes more than the predetermined
value, the locking member 35 is displaced by the oil pressure in
the radial direction towards an outer periphery of the rotating
body against the urging force of the spring 36, the guide groove
35a of the locking member 35 communicates with the circumferential
grooves 34a, 34b (refer to FIG. 6(a)). In this way, the lock of the
lock engaging projection portion 38a is released by the locking
member 35, the first and second rotating bodies 21, 24 can rotate
relatively to each other. Thus, by the rotation of the second
rotating body 24 in an advancing direction, the lock engaging
projection portion 38a displaces, together with the second rotating
body 24, from the retarding side circumferential groove 34b to the
advancing side circumferential groove 34a through the guide groove
35a of the locking member 35 (refer to FIG. 6 (b), (c)). Then, the
lock engaging projection portion 38a abuts with the end portion of
the circumferential groove 34a, the second rotating body 24 is
maintained in a maximum advanced position (refer to FIG. 6(d)).
[0056] As shown above, when the second rotating body 24 rotates
from a position situated on a retarding side towards an advancing
side, the oil pressure supply hole 33 is connected with the
advancing chamber communication passage 39a by the oil passage
switching valve 40 and an oil pressure is applied to the locking
member 35 from the advancing oil pressure chamber 25.
[0057] Hereafter, the displacement of the locking member when the
second rotating body 24 rotates in a retarding direction will be
described.
[0058] When the lock engaging projection portion 38a separates from
the guide groove 35a of the locking member 35 and is positioned in
the circumferential groove 34a, the locking member 35 is retained
in a balanced state by the oil pressure applied to its tip and the
urging force of the spring 36. Normally, in this state, an oil
pressure in the advancing oil pressure chamber 25 or the retarding
oil pressure chamber 26 is applied as a lock releasing oil
pressure. However, when the applied oil pressure is abnormally
reduced or the engine is stopped, the possibility arises that the
oil pressure may be reduced to zero. In such a state, it is
required to return it quickly to the maximum retarding position and
to lock the first and second rotating bodies 21, 24. Thus, in a
case where the lock engaging projection portion 38a is positioned
in the circumferential groove 34a and the oil pressure is
conspicuously reduced, a reverse rotation force is generated by the
reactive force of the camshaft 1 to return the second rotating body
24 to a position situated on a retarding side. As a result, the
lock engaging projection portion 38a enters the guide groove 35a of
the locking member 35 and returns to the circumferential groove 34b
on a maximum retarding side. At this time, even if there is no oil
pressure to retain or release the locking member 35, a force is
applied by which the lock engaging projection portion 38a presses
the outer wall face of the guide groove 35a in the radial direction
towards its outer periphery, and it is possible to displace the
locking member 35 mechanically in the radial direction towards the
outer periphery of the rotating body against the urging force of
the spring 36. Thus, the second rotating body 24 is displaced
quickly in the retarding direction and reaches the maximum
retarding position. As a result, the engaging projection portion
38a is displaced from the guide groove 35a of the locking member 35
to the circumferential groove 34b on the maximum retarded side. At
this time, the locking member 35 is displaced in the radial
direction towards a center of the rotating body by the urging force
of the spring 36, the movement of the engaging projection portion
38a is restricted by the side wall of the locking member 35, and
the relative rotation of the first and the second rotating body 21,
24 is restricted.
[0059] As described above, according to the first embodiment of the
present invention, a radial groove 32 is provided on an axial end
face of the first rotating body 21, and a locking member 35 is
inserted in the radial groove 32 so as to slide therein. Thus, it
is possible to form the radial groove 32 on the axial end face of
the first rotating body 21 (first housing 22) in the space region
between the shoes 23a which are adjacent to each other in the
circumferential direction of the first rotating body 21. Namely, it
is not necessary to form the radial groove 32 on the shoe 23a. As a
result, each shoes 23 of the first rotating body 21 (second housing
23) can be formed with approximately the same length in a
circumferential direction thereof and it is possible to expand the
angular range to be regulated by the valve timing regulation
device. Further, it is possible to greatly reduce the degree of
unbalance with respect to the rotation center of the first rotating
body 21 and thus solve problems such as the mechanical strength and
the generation of vibration. Furthermore, according to the first
embodiment of the present invention, a circumferential groove 34a,
34b extends in a circumferential direction of the housing 22 from
both sides of the radial groove 32, namely, the circumferential
groove 34a, 34b is divided in the longitudinal direction by the
radial groove 32, and the groove width of the guide groove 35a
gradually increases towards one of the divided circumferential
grooves 34a. As a result, the lock engaging projection portion 38a
which is displaced in the expanding direction of the groove width
of the guide groove 35a can quickly be introduced into the guide
groove 35a when the locking member 35 is slightly displaced by the
oil pressure against the urging force of the spring 36. Thus, the
advantage is obtained that the response characteristics of the lock
engaging projection portion 38a following the displacement of the
locking member 35 in a direction resisting the spring 36 are
improved. Furthermore, since the locking member 35 has a
quadrangular shape in cross section and the radial groove 32
storing the locking member 35 has a cross section adapted to allow
sliding of the locking member 35, it is possible to easily mold the
locking member by sintered metal or the like, thereby improving a
mass production efficiency. In addition, since the manufacture of
die for molding is also simplified, the cost can be reduced.
Furthermore, according to the first embodiment of the present
invention, a plate 37 is interposed between the first and second
rotating bodies 21, 24 so as to cover the circumferential grooves
34a, 34b and the radial groove 32, the circumferential grooves 34a,
34b and the exposed surface of the locking member 35 inserted into
the radial groove 32 are covered with the plate 37. Thus, the
communication of the circumferential grooves 34a, 34b and the
radial groove 32 with the advancing oil pressure chamber 25 and the
retarding oil pressure chamber 26 can be prevented and it is
possible to improve the sliding characteristics of the locking
member 35. Furthermore, a common oil pressure passage 39 which
communicates with each of the advancing oil pressure chamber 25 and
the retarding oil pressure chamber 26 is provided in the plate 37,
an oil passage switching valve 40 which switches the oil pressure
applying passage to the locking member 35 between either the
advancing oil pressure chamber 25 and the retarding oil pressure
chamber 26 is provided in the oil pressure passage 39. Thus, it is
possible to apply selectively an oil pressure to the locking member
35 from either the advancing oil pressure chamber 25 or the
retarding oil pressure chamber 26. Further, it is possible to
retain the first rotating body 21 and the second rotating body 24
in a normally lock released state as long as the applied oil
pressure is not less than a predetermined value. Furthermore, an
engaging projection portion 38 is provided on both surfaces of the
plate and one of the engaging projections 38a can engage with the
guide groove 35a and the circumferential grooves 34a, 34b. The
mounting engaging projection portion 38b on the opposite side of
the plate 37 is engaged and fixed to the engaging hole 43 provided
on the second rotating body 24, and the engaging protrusion 41 of
the plate 37 is engaged with the engaging concave portion 42 of the
second rotating body 24. Thus, it is possible to simply mount the
plate 37 on the second rotating body 24 to rotate together with the
second rotating body 24. Further, the engagement of the engaging
hole 43 with the mounting engaging projection 38b and the
engagement of the engaging concave portion 42 with the engaging
protrusion 41 allow sufficient strength when assembled.
Furthermore, the engaging projections 38 are formed by a single
engaging member which passes through the plate 37. The lock
engaging projection 38a projecting from one face of the plate 37 is
used for locking, and the mounting engaging projection 38b
projecting from the opposite face of the plate 37 is engaged with
the engagement hole 43. Thus, it is not necessary to provide the
lock engaging projection 38a and the mounting engaging projection
38b as separate members. As a result, the structure of the unit
including the engaging projections and the plate is simplified by
the reduction in number of components, costs can be reduced, and
mass production efficiency can be improved.
[0060] Embodiment 2
[0061] FIG. 7 is a cross sectional view of a lock mechanism for a
valve timing regulation device according to a second embodiment of
the present invention. In the above first embodiment, a plate 37 is
inserted into a concave portion 31 which is formed partially on an
end face in an axial direction of the first housing 22 of the first
rotating body 21. However, in the second embodiment, the plate 37
is composed of an annular plate which is co-axial with the housing
22, the plate 37 is adapted to rotate in an integrated manner with
the second rotating body 24 which slides on the end face in an
axial direction of the housing 22 in the circumferential direction.
Thus, in the second embodiment, it is possible to obtain the same
advantages as the above first embodiment.
[0062] Embodiment 3
[0063] FIG. 8 is a plan view of a plate of a valve timing
regulation device according to a third embodiment of the present
invention. In the figure, 37a denotes a circumferential slit
provided in the annular plate 37, and the lock engaging projection
38a is slidably inserted into the circumferential slit. 37b denotes
a plurality of through holes for bolts provided in the plate 37.
The plate 37 is fixed to the housing 22 shown in FIG. 7 by bolts
(not shown) through these through holes 37b. That is to say, in the
above second embodiment, the annular plate 37 is adapted to rotate
together with the second rotating body 24. On the other hand, in
this third embodiment, the annular plate 37 is disposed between the
housing 22 of the first rotating body 21 and the second rotating
body (rotor) 24 as shown in FIG. 7 and is adapted to rotate
together with the housing 22. In addition, in the third embodiment,
the lock engaging projection 38a is integrated with the second
rotating body 24 and a slit 37a is provided on the plate 37 for
inserting the lock engaging projection 38a so as to slide in the
circumferential direction of the plate 37. Thus, in the third
embodiment, the same advantage as the first embodiment can be
obtained.
[0064] In the first embodiment, a lock mechanism 30 is assembled
with the first rotating body 21. However, the same advantage can be
obtained by assembling the lock mechanism 30 with the second
rotating body 24.
[0065] As shown above, in a lock mechanism for a valve timing
regulation device according to the present invention, it is
possible to assemble a locking member onto an end face in an axial
direction other than that of a vane or a shoe in either a first
rotating body or a second rotating body. As a result, each vane or
each shoe can be formed with approximately the same circumferential
length. Thus, it is possible to expand the angular range regulated
by the valve timing regulation device and to reduce the degree of
unbalance in the device by a large amount.
* * * * *