U.S. patent application number 13/032931 was filed with the patent office on 2011-08-25 for valve timing adjuster.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Ichiro KATO.
Application Number | 20110203540 13/032931 |
Document ID | / |
Family ID | 44356975 |
Filed Date | 2011-08-25 |
United States Patent
Application |
20110203540 |
Kind Code |
A1 |
KATO; Ichiro |
August 25, 2011 |
VALVE TIMING ADJUSTER
Abstract
A valve timing adjuster includes a housing and a vane rotor. A
hub portion of the vane rotor includes an advance passage and a
retard passage. One of a shoe of the housing and the hub portion
includes an advance groove and a retard groove. The advance groove
provides communication between an advance chamber and the advance
passage at a full retard position. The retard groove provides
communication between a retard chamber and the retard passage at a
full advance position. The advance groove and the retard groove are
spaced apart from each other along a longitudinal axis of the
housing.
Inventors: |
KATO; Ichiro;
(Gamagori-city, JP) |
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
44356975 |
Appl. No.: |
13/032931 |
Filed: |
February 23, 2011 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 2001/34423
20130101; F01L 2001/34433 20130101; F01L 1/3442 20130101; F01L
2001/34479 20130101 |
Class at
Publication: |
123/90.17 |
International
Class: |
F01L 1/344 20060101
F01L001/344 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 23, 2010 |
JP |
2010-37086 |
Claims
1. A valve timing adjuster for adjusting timing of opening and
closing at least one of an intake valve and an exhaust valve by
changing a phase between a drive shaft of an internal combustion
engine and a driven shaft, which opens and closes the at least one
of the intake valve and the exhaust valve based on a driving force
of the drive shaft, the valve timing adjuster comprising: a housing
that is rotatable synchronously with one of the drive shaft and the
driven shaft, wherein the housing having: a tubular peripheral
wall; a shoe that radially inwardly projects from the peripheral
wall; a front plate that is provided on one side of the peripheral
wall along a longitudinal axis of the housing; and a rear plate
that is provided on the other side of the peripheral wall along the
longitudinal axis; and a vane rotor that is rotatable synchronously
with the other one of the drive shaft and the driven shaft,
wherein: the vane rotor includes: a hub portion that is provided
coaxially with the housing, wherein the hub portion slidably
contacts a slidably contacting surface of the shoe located on a
radially inner side thereof, wherein the hub portion has a
generally hollow cylindrical shape, wherein the peripheral wall,
the shoe, and the hub portion defines therebetween a pressure
chamber; and a vane that radially outwardly projects from the hub
portion to divide the pressure chamber into an advance chamber and
a retard chamber that are arranged in a circumferential direction
of the housing; the vane rotor rotates relative to the housing
based on pressure of working fluid that is supplied to one of the
advance chamber and the retard chamber; the hub portion includes:
an advance passage that has an opening, which faces an advance side
of the slidably contacting surface adjacent the advance chamber
when the vane rotor is located at a full retard position relative
to the housing; and a retard passage that has an opening, which
faces a retard side of the slidably contacting surface adjacent the
retard chamber when the vane rotor is located at a full advance
position relative to the housing; one of the shoe and the hub
portion includes: an advance groove that provides communication
between the advance chamber and the opening of the advance passage
when the vane rotor is located at the full retard position relative
to the housing; and a retard groove that provides communication
between the retard chamber and the opening of the retard passage
when the vane rotor is located at the full advance position
relative to the housing; and the advance groove and the retard
groove are spaced apart from each other along the longitudinal axis
of the housing.
2. The valve timing adjuster according to claim 1, wherein: the one
of the shoe and the hub portion is the shoe; the advance groove and
the retard groove are formed on the slidably contacting surface of
the shoe; one of the advance groove and the retard groove is
provided on a side of the slidably contacting surface adjacent the
rear plate; and the other one of the advance groove and the retard
groove is provided on the other side of the slidably contacting
surface adjacent the front plate.
3. The valve timing adjuster according to claim 2, wherein: the
advance groove and the retard groove extend in the circumferential
direction without extending along the longitudinal axis.
4. The valve timing adjuster according to claim 1, wherein: the one
of the shoe and the hub portion is the hub portion; the advance
groove and the retard groove are formed on an outer wall of the hub
portion; one of the advance groove and the retard groove is
provided on a side of the outer wall of the hub portion adjacent
the rear plate; and the other one of the advance groove and the
retard groove is provided on the other side of the outer wall of
the hub portion adjacent the front plate.
5. The valve timing adjuster according to claim 4, wherein: the
advance groove and the retard groove extend in the circumferential
direction without extending along the longitudinal axis.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2010-37086 filed on Feb.
23, 2010.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a valve timing adjuster for
an internal combustion engine, which adjuster adjusts timing of
opening and closing at least one of an intake valve and an exhaust
valve.
[0004] 2. Description of Related Art
[0005] Conventionally, a valve timing adjuster is known to adjust
timing of opening and closing at least one of an intake valve and
an exhaust valve by changing a phase between a crankshaft and a
camshaft. The crankshaft serves as a drive shaft of an internal
combustion engine (hereinafter referred to as an engine). The
camshaft serves as a driven shaft that opens and closes the intake
valve and/or the exhaust valve based on the driving force of the
crankthaft.
[0006] In general, the valve timing adjuster has a housing and a
vane rotor. The housing rotates synchronously with the crankshaft,
and receives therein the vane rotor. The vane rotor is rotatable
synchronously with the camshaft. The housing has shoes that
radially inwardly project from the tubular peripheral wall of the
housing, and shoes slides on an outer wall of the vane rotor.
Multiple pressure chambers are sectioned by the shoes between an
inner wall of the housing and the outer wall of the vane rotor.
Also, the vane rotor has multiple vanes that divide the multiple
pressure chambers into advance chambers and retard chambers. When
pressures of oil supplied to the advance chambers or the retard
chambers are applied to pressure receiving surfaces of the multiple
vanes, the housing rotates relative to the vane rotor, and thereby
the phase between the crankshaft and the camshaft is changed
accordingly.
[0007] The enlargement of a phase changeable angle of the valve
timing adjuster has been demanded in order to address various
operational conditions of the engine, and in order to improve the
engine performance and the exhaust gas purification capability.
Also, in order to improve the easiness of mounting the valve timing
adjuster to the engine, the reduction in the size of the valve
timing adjuster has been also demanded.
[0008] In order to enlarge the phase changeable angle of the valve
timing adjuster, the numbers of the pressure chambers and the vanes
are reduced, and thereby the dimensions of the remaining pressure
chambers are increased in the circumferential direction to increase
the volumes thereof. However, the total area of the vanes, which
receive oil pressure, is reduced with the reduction of the number
of the vanes accordingly, and thereby torque applied to the housing
and the vane rotor are reduced accordingly. When the torques are
reduced below the reaction force of the camshaft, it becomes
difficult to rotate the vane rotor relative to the housing. As a
result, the range of the engine rotational speed, in which the
valve timing adjuster is effectively phase-controlled, may be
limited disadvantageously.
[0009] In contrast, in a case where pressure receiving surfaces of
the vanes are increased in order to increase torque applied to the
housing and the vane rotor, the size of the valve timing adjuster
may be increased disadvantageously.
[0010] In JP3906482, a valve timing adjuster operates oil pressure
higher in the advance control than in the retard control. In the
above, oil pressure is supplied to the advance chambers through
advance passages, which are formed on a vane rotor. Oil pressure is
supplied to the retard chambers through retard passages, which are
formed on a rear plate. An angle .theta. is defined between the
advance passage and the retard passage when controlled at the full
retard position. An angle .phi. is defined between the advance
passage and the retard passage when controlled at the full advance
position. The advance passage and the retard passage are formed
such that the angle .theta. is greater than the angle .phi.. Thus,
leakage (erroneous communication) of oil between the advance
chamber and the retard chamber is limited during an advance
operation, in which the phase of the vane rotor is advanced from
the full retard position.
[0011] However, in JP3906482, the advance passage is formed on a
longitudinal end surface of the vane rotor to have a curved shape,
and the retard passage is formed on the opposed surface of the rear
plate that races the end surface of the vane rotor. If the advance
passage is formed to have the above curved shape, and
simultaneously if the advance passage and the retard passage are
separately formed from each other, each passage has to have a
complex structure, and thereby man hour of processing the product
is disadvantageously increased.
SUMMARY OF THE INVENTION
[0012] The present invention is made in view of the above
disadvantages. Thus, it is an objective of the present invention to
address at least one of the above disadvantages.
[0013] To achieve the objective of the present invention, there is
provided a valve timing adjuster that adjusts timing of opening and
closing at least one of an intake valve and an exhaust valve by
changing a phase between a drive shaft of an internal combustion
engine and a driven shaft, which opens and closes the at least one
of the intake valve and the exhaust valve based on a driving force
of the drive shaft. The valve timing adjuster includes a housing
and a vane rotor. The housing is rotatable synchronously with one
of the drive shaft and the driven shaft. The housing has a tubular
peripheral wall, a shoe, a front plate, and a rear plate. The shoe
radially inwardly projects from the peripheral wall. The front
plate is provided on one side of the peripheral wall along a
longitudinal axis of the housing. The rear plate is provided on the
other side of the peripheral wall along the longitudinal axis. The
vane rotor is rotatable synchronously with the other one of the
drive shaft and the driven shaft. The vane rotor includes a hub
portion and a vane. The hub portion is provided coaxially with the
housing, wherein the hub portion slidably contacts a slidably
contacting surface of the shoe located on a radially inner side
thereof, wherein the hub portion has a generally hollow cylindrical
shape, wherein the peripheral wall, the shoe, and the hub portion
defines therebetween a pressure chamber. The vane radially
outwardly projects from the hub portion to divide the pressure
chamber into an advance chamber and a retard chamber that are
arranged in a circumferential direction of the housing. The vane
rotor rotates relative to the housing based on pressure of working
fluid that is supplied to one of the advance chamber and the retard
chamber. The hub portion includes an advance passage and a retard
passage. The advance passage has an opening, which faces an advance
side of the slidably contacting surface adjacent the advance
chamber when the vane rotor is located at a full retard position
relative to the housing. The retard passage has an opening, which
faces a retard side of the slidably contacting surface adjacent the
retard chamber when the vane rotor is located at a full advance
position relative to the housing. One of the shoe and the hub
portion includes an advance groove and a retard groove. The advance
groove provides communication between the advance chamber and the
opening of the advance passage when the vane rotor is located at
the full retard position relative to the housing. The retard groove
provides communication between the retard chamber and the opening
of the retard passage when the vane rotor is located at the full
advance position relative to the housing. The advance groove and
the retard groove are spaced apart from each other along the
longitudinal axis of the housing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention, together with additional objectives, features
and advantages thereof, will be best understood from the following
description, the appended claims and the accompanying drawings in
which:
[0015] FIG. 1 is a cross-sectional view of a valve timing adjuster
according to the first embodiment of the present invention, the
view being taken along a line I-I in FIG. 2;
[0016] FIG. 2 is a cross-sectional view of the valve timing
adjuster taken along a line II-II in FIG. 1;
[0017] FIG. 3 is a schematic diagram of a driving force
transmission system having the valve timing adjuster according to
the first embodiment;
[0018] FIG. 4 is a diagram exclusively illustrating a peripheral
wall and shoes, of the valve timing adjuster according to the first
embodiment
[0019] FIG. 5 is a view observed in a direction V in FIG. 4;
[0020] FIG. 6 is an enlarged view of a peripheral wall and shoes of
a valve timing adjuster according to the second embodiment of the
present invention;
[0021] FIG. 7 is a cross-sectional view of a valve timing adjuster
according to the third embodiment of the present invention, the
view being taken along a line VII-VII in FIG. 8;
[0022] FIG. 8 is a cross-sectional view of the valve timing
adjuster taken along a line VIII-VIII in FIG. 7;
[0023] FIG. 9 is a diagram exclusively illustrating a vane rotor of
the valve timing adjuster according to the third embodiment;
[0024] FIG. 10 is a view observed in a direction X of FIG. 9;
[0025] FIG. 11 is an enlarged view of a vane rotor of a valve
timing adjuster according to the fourth embodiment of the present
invention; and
[0026] FIG. 12 is an enlarged view of a peripheral wall and shoes
of a valve timing adjuster according to a comparison example.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0027] Embodiments of the present invention will be described below
with reference to accompanying drawings.
First Embodiment
[0028] A valve timing adjuster according to the first embodiment of
the present invention is shown in FIGS. 1 to 5.
[0029] In a driving force transmission system, as shown in FIG. 3,
a gear 3 is fixed to a crankshaft 2 that serves as a drive shaft of
an engine 1. Gears 6, 113 are respectively fixed to camshafts 4, 5
that serve as driven shafts. A chain 7 is installed over the gear 3
and the gears 6, 113, and transmits a driving force from the
crankshaft 2 to the camshafts 4, 5. The camshaft 4 opens and closes
an intake valve 8, and the other camshaft 5 opens and closes an
exhaust valve 9. A valve timing adjuster 10 of the present
embodiment is a hydraulic control adjuster that employs hydraulic
oil as working fluid. The valve timing adjuster 10 adjusts timing
of opening and closing the intake valve 8 in a state, where the
gear 113 is connected to the chain 7, and where a vane rotor is
connected to the camshaft 4.
[0030] As shown in FIGS. 1 and 2, the valve timing adjuster 10 has
a housing 12 and a vane rotor 20.
[0031] The housing 12 includes a tubular peripheral wall 13, four
shoes 14 to 17, a front plate 18 and a rear plate 11. The four
shoes 14 to 17 radially inwardly projects from the peripheral wall
13. The front plate 18 is provided on one side of the peripheral
wall 13 along a longitudinal axis of the housing 12, and the rear
plate 11 is provided on the other side of the peripheral wall 13
along the longitudinal axis. In other words, the front plate 18 is
provided on one longitudinal side of the peripheral wall 13 in a
longitudinal direction of the housing 12, and the rear plate 11 is
provided on the other longitudinal side of the peripheral wall 13
opposite from the one longitudinal side.
[0032] Each of the shoes 14 to 17 has a generally trapezoidal
shape, and the shoes 14 to 17 are provided in a circumferential
direction of the peripheral wall 13 of the housing 12 at equal
intervals. Four pressure chambers 50 are defined between the
adjacent shoes arranged in the circumferential direction.
[0033] The front plate 18 has an axial hole 18a, through which the
camshaft 4 extends in the longitudinal direction.
[0034] The rear plate 11 has the gear 113 at a position radially
outward of the rear plate 11. Also, the rear plate 11 has an axial
hole 11a, through which the camshaft 4 extends in the longitudinal
direction. The front plate 18 and the rear plate 11 are rotatable
relative to the camshaft 4.
[0035] The vane rotor 20 is coaxially received within the housing
12. The vane rotor 20 has a hub portion 21 and four vanes 24 to 27.
The hub portion 21 has a generally hollow cylindrical shape, and
vanes 24 to 27 radially outwardly project from the hub portion
21.
[0036] The hub portion 21 has an axial hole 21a, through which the
camshaft 4 extends in the longitudinal direction. The hub portion
21 is fixed to the camshaft 4 though a method, such as press
fitting, welding, or a bolt. Due to the above, the vane rotor 20 is
rotatable synchronously with the camshaft 4.
[0037] The vanes 24 to 27 divide corresponding pressure chambers 50
into retard chambers 51 to 54 and advance chambers 55 to 58, and
the retard chambers 51 to 54 and the advance chambers 55 to 58 are
arranged in a circumferential direction of the housing 12.
[0038] The hub portion 21 has an outer diameter that is slightly
smaller than an inner diameter of the shoes 14 to 17. Therefore,
the shoes 14 to 17 have slidably contacting surfaces 41 to 44 at
radially inner side thereof, and the slidably contacting surfaces
41 to 44 slidably contact a radially outer wall of the hub portion
21. The above arrangement of the slidably contacting surfaces 41 to
44 of the shoes 14 to 17 and the outer wall of the hub portion 21
limits leakage or circulation of hydraulic oil between (a) the
retard chambers 51 to 54, which are formed on one circumferential
side of the shoes 14 to 17, and (b) the advance chambers 55 to 58,
which are formed on the other circumferential side of the shoes 14
to 17.
[0039] Each of the vanes 24 to 27 has an outer diameter that is
slightly smaller than an inner diameter of the peripheral wall 13
of the housing 12. Seal members 28 are made of, for example, a
resin, and the seal members 28 are fitted into radially outer walls
of the vanes 24 to 27. The seal members 28 are pressed against the
peripheral wall 13 by resilient force of respective leaf springs
(not shown). The seal members 28 limit leakage of hydraulic oil
through clearances between (a) the radial outer walls of the vanes
24 to 27 and (b) the peripheral wall 13, and thereby limiting
communication of hydraulic oil between (a) the retard chambers 51
to 54 and (b) the advance chambers 55 to 58.
[0040] The vane 27 is provided with a hole 29, and the hole 29 is
provided with a stopper piston (not shown). The rear plate 11 has a
fitting ring, and the stopper piston is fitted into the fitting
ring of the rear plate 11 to regulate the relative rotation between
the housing 12 and the vane rotor 20. The description of the
configuration of the stopper piston is omitted.
[0041] The valve timing adjuster 10 of the present embodiment
rotates clockwise when observed in a direction indicated by an
arrow A in FIG. 2. The above rotational direction is defines as an
advance direction.
[0042] Arrows labeled as "advance" and "retard" in FIG. 1 indicate
an advance direction and a retard direction of the vane rotor 20
relative to the housing 12.
[0043] The housing 12 is rotatable relative to the vane rotor 20.
In other words, when pressure of oil supplied to each of the retard
chambers 51 to 54 is applied to the inner wall the housing 12 and
the outer wall of the vane rotor 20, the vane rotor 20 rotates
relative to the housing 12 in the retard direction. In contrast,
when pressure of oil supplied to the advance chambers 55 to 58 is
applied to the inner wall of the housing 12 and the outer wall of
the vane rotor 20, the vane rotor 20 rotates relative to the
housing 12 in the advance direction. FIG. 1 shows a phase
changeable angle 81 of the valve timing adjuster 10. For example,
the phase of the vane rotor 20 relative to the housing 12 is
changeable within the phase changeable angle .theta.1.
[0044] It should be noted that in FIG. 1, the phase of the vane
rotor 20 relative to the housing 12 is controlled such that the
vane rotor 20 is positioned at a full advance position.
[0045] Next, a supply passage of oil pressure of the valve timing
adjuster 10 will be described.
[0046] The camshaft 4 and the hub portion 21 define therein retard
passages 31 to 34 and advance passages 35 to 38, each of which
extends in a radial direction. The retard passages 31 to 34 are
formed at positions such that the openings of the retard passages
31 to 34 are located at respective retard sides of the slidably
contacting surfaces 41 to 44 adjacent the retard chambers 51 to 54
when the phase of the vane rotor 20 relative to the housing 12 is
controlled to the full advance position. In contrast, the advance
passages 35 to 38 are formed at positions such that the openings of
the advance passages 35 to 38 are located at respective advance
sides of the slidably contacting surfaces 41 to 44 adjacent the
advance chambers 55 to 58 when the phase of the vane rotor 20
relative to the housing 12 is controlled to the full retard
position.
[0047] The slidably contacting surfaces 41 to 44 have retard
grooves 61 to 64 and advance grooves 65 to 68, respectively. The
retard grooves 61 to 64 are formed at positions such that the
retard grooves 61 to 64 provide communication between the openings
of the retard passages 31 to 34 and the retard chambers 51 to 54
when the phase of the vane rotor 20 relative to the housing 12 is
controlled to the full advance position. In contrast, the advance
grooves 65 to 68 are formed at positions such that the advance
grooves 65 to 68 provide communication between the openings of the
advance passages 35 to 38 and the advance chambers 55 to 58 when
the phase of the vane rotor 20 relative to the housing 12 is
controlled to the full retard position.
[0048] The retard groove, the advance groove, and the slidably
contacting surface, which is provided with the retard and advance
grooves, will be detailed with reference to FIG. 4 and FIG. 5. FIG.
4 shows only the peripheral wall 13 and the shoes 14 to 17 of the
valve timing adjuster 10. FIG. 5 is a view observed in a direction
V in FIG. 4. In other words, FIG. 5 shows the shoe 14 and a part of
the peripheral wall 13 in the vicinity of the shoe 14.
[0049] It should be noted that FIG. 5 shows a position of the
opening of the retard passage 31 by a dashed line when the phase of
the vane rotor 20 relative to the housing 12 is controlled to the
full advance position. Also, FIG. 5 shows a position of the opening
of the advance passage 35 by another dashed line when the phase of
the vane rotor 20 relative to the housing 12 is controlled to the
full retard position.
[0050] The retard groove 61 is provided to one longitudinal end of
the slidably contacting surface 41, and the advance groove 65 is
provided the other longitudinal end of the slidably contacting
surface 41 opposite from the one longitudinal end. Specifically,
the retard groove 61 opens to a wall'surface 181 of the shoe 14
adjacent the front plate 18, and also opens to a wall surface 145
of the shoe 14 adjacent the retard chamber 51. In contrast, the
advance groove 65 opens to a wall surface 111 of the shoe 14
adjacent the rear plate 11, and also opens to a wall surface 146 of
the shoe 14 adjacent the advance chamber 55. For example, the
retard groove 61 and the advance groove 65 are spaced apart from
each other in the longitudinal direction of the housing 12. Also,
the retard groove 61 and the advance groove 65 are spaced apart
from each other in the circumferential direction of the housing 12.
Thus, the retard groove 61 and the advance groove 65 are positioned
on the slidably contacting surface 41 diagonally with respect to
each other. Thus, a distance L2 measured between the retard groove
61 and the advance groove 65 is maximized. Also, because the retard
groove 61 and the advance groove 65 are provided to the slidably
contacting surface 41 diagonally with each other as above, it is
possible to shorten a distance L5 measured between the retard
groove 61 and the advance groove 65 in a circumferential direction.
Also, it is possible to shorten a distance L1 of the slidably
contacting surface 41 in the circumferential direction accordingly.
It should be noted that the retard groove 61 may overlap with the
advance groove 65 when observed in the longitudinal direction (a
direction B in FIG. 5).
[0051] A distance L3 is measured between the retard groove 61 and
the wall surface 146 of the shoe 14 adjacent the advance chamber
55. A distance L4 is measured between the advance groove 65 and the
wall surface 145 of the shoe 14 adjacent the retard chamber 51. The
distance L1 is a dimension of the slidably contacting surface 41 in
the circumferential direction as above. The distance L2 is
diagonally measured between the retard groove 61 and the advance
groove 65. All of the distances L1, L2, L3, and L4 are determined
such that the sealing performance of the clearance between the
slidably contacting surface 41 and the outer wall of the hub
portion 21 is substantially achievable. Due to the above
configuration, the leakage (erroneous communication) of hydraulic
oil between (a) the retard chamber 51 formed on one circumferential
side of the shoe 14 and (b) the advance chamber 55 formed on the
other circumferential side of the shoe 14 is effectively
limited.
[0052] Next, the operation of the valve timing adjuster 10 will be
described.
<During Starting of Engine>
[0053] When the engine 1 is not running, the stopper piston is
fitted into the fitting ring. Immediately after the engine 1 is
started, a hydraulic pump 90 has not sufficiently supplied
hydraulic oil to the retard chambers 51 to 54 and the advance
chambers 55 to 58. Thus, the stopper piston remains fitted into the
fitting ring, and thereby the phase of the camshaft 4 relative to
the crankshaft 2 is held at the full retard position. As a result,
it is possible to prevent the noise of the collision between the
housing 12 and the vane rotor 20 caused by variation of torque
applied to the camshaft 4 before hydraulic oil is sufficiently
supplied to each pressure chamber 50.
<After Engine Start>
[0054] After the engine start, when the hydraulic pump 90 supplies
hydraulic oil, the stopper piston moves out of the fitting ring or
is disengaged from the fitting ring, and thereby the vane rotor 20
is allowed to rotate relative to the housing 12. Then, by
controlling the pressure of oil in the retard chambers 51 to 54 and
the advance chambers 55 to 58, it is possible to adjust the phase
difference of the camshaft 4 relative to the crankshaft 2.
<During Advance Operation>
[0055] When the valve timing adjuster 10 is controlled under the
advance operation, an electronic control device (ECU) 91 controls
drive electric current supplied to a switching valve 92. As a
result, the switching valve 92 connects the hydraulic pump 90 with
an advance passage 93, and connects a retard passage 94 with an oil
pan 95. Hydraulic oil discharged from the hydraulic pump 90 is
delivered through the advance passage 93, 35 to 38 and the advance
grooves 65 to 68, and is supplied to the advance chambers 55 to 58.
In contrast, hydraulic oil in the retard chambers 51 to 54 is
delivered through the retard grooves 61 to 64 and the retard
passages 31 to 34, 94, and is drained to the oil pan 95. Oil
pressure in the advance chambers 55 to 58 is applied to the housing
12 and to the vanes 24 to 27, and generates a torque that urges the
vane rotor 20 in the advance direction. Thus, the vane rotor 20
rotates relative to the housing 12 in the advance direction.
<During Retard Operation>
[0056] When the valve timing adjuster 10 is controlled under the
retard operation, the ECU 91 controls drive electric current
supplied to the switching valve 92. Thus, the switching valve 92
connects the hydraulic pump 90 with the retard passage 94, and
connects the advance passage 93 with the oil pan 95. Hydraulic oil
discharged from the hydraulic pump 90 is delivered through the
retard passage 94, 31 to 34 and the retard grooves 61 to 64, and is
supplied to the retard chambers 51 to 54. In contrast, hydraulic
oil the advance chambers 55 to 58 is delivered through the advance
passages 35 to 38, 93 and the advance grooves 65 to 68, and is
drained to the oil pan 95. Oil pressure in the retard chambers 51
to 54 is applied to the housing 12 and the vanes 24 to 27, and
generates a torque that urges the vane rotor 20 in the retard
direction. As a result, the vane rotor 20 rotates relative to the
housing 12 in the retard direction.
<Holding at Intermediate Position>
[0057] When the vane rotor 20 reaches a target phase, the ECU 91
controls a duty ratio of the drive electric current supplied to the
switching valve 92. Then, the switching valve 92 disconnects the
hydraulic pump 90 from the retard passage 94 and also disconnects
the hydraulic pump 90 from the advance passage 93. Thus, discharge
of hydraulic oil from the retard chambers 51 to 54 and the advance
chambers 55 to 58 to the oil pan 95 is prevented. Thus, the vane
rotor 20 is held at the target phase.
<During Stopping Engine>
[0058] When a command of stopping the engine 1 is issued during the
operation of the valve timing adjuster 10, the vane rotor 20 is
rotated relative to the housing 12 in the retard direction in a
manner similar to the retard operation, and the rotation of the
vane rotor 20 is stopped at the full retard position. In the above
state, the ECU 91 stops the operation of the hydraulic pump 90, and
causes the switching valve 92 to connect the retard passage 94 with
the oil pan 95. Due to the above operation, the stopper piston is
brought into fitting with the fitting ring.
Comparison Example
[0059] FIG. 12 shows an enlarged view of a peripheral wall and a
shoe of a valve timing adjuster according to the comparison
example. It should be noted that similar components of the
comparison example and multiple later-described embodiments, which
are similar to the components of the first embodiment will be
indicated by the same numerals, and the description will be
omitted.
[0060] In the comparion example, a retard groove 611 and an advance
groove 651 are formed on the slidably contacting surface 411 to
extend over the length of the slidably contacting surface 411 in
the longitudinal direction. In other words, the retard groove 611
and the advance groove 651 are formed from (a) the end surface 181
of the slidably contacting surface 411 adjacent the front plate to
the other end surface 111 of the slidably contacting surface 411
adjacent the rear plate. In FIG. 12, in order to clearly describe
the positions of the retard groove 611 and the advance groove 651,
the positions of the retard groove 611 and the advance groove 651
are shaded by diagonal lines.
[0061] In the comparison example, a distance L9 measured between
the retard groove 611 and the advance groove 651 is determined such
that the sealing performance is substantially achievable. As a
result, a distance L10 of the shoe 141 in the circumferential
direction measured as shown in FIG. 12 is made longer than the
distance L1 of the shoe 14 in the circumferential direction
according to the first embodiment.
Advantages of First Embodiment
[0062] In the first embodiment, the retard grooves 61 to 64 and the
advance grooves 65 to 68 are provided to the slidably contacting
surfaces 41 to 44 diagonally with respect to each other. When the
distance L2 measured between the retard grooves 61 to 64 and the
advance grooves 65 to 68 is maximized as above, it is possible to
enlarge the sealing area, and thereby improving the sealing
performance (or sealing capability) of limiting hydraulic oil from
leaking through the clearance between the slidably contacting
surfaces 41 to 44 and the outer wall of the hub portion 21.
[0063] In the valve timing adjuster 10 of the first embodiment, the
retard groove 61 and the advance groove 65 are provided to the
slidably contacting surface 41 at positions diagonally with each
other as described above. Thus, even when the sealing performance
in the first embodiment is equivalent to the sealing performance in
the comparison example, or in other words, even when the distance
L9 in the comparison example is generally equivalent to any one of
the distances L2, L3, L4 in the first embodiment, it is possible to
reduce the distance L5 of the first embodiment, and thereby
reducing the distance L1 of the first embodiment. As a result, it
is possible to enlarge the dimension of the pressure chambers 50 in
the circumferential direction by an amount equivalent to the
seduction in the distance L1 or in the distance L5. Therefore, it
is possible to increase the phase changeable angle .theta.1
effectively.
[0064] Also, for example, if the distance L1 of the shoe 14 in the
circumferential direction is reduced, and simultaneously the outer
diameters the housing 12 and the vane rotor 20 are reduced in a
state, where the phase changeable angle 01 of the first embodiment
remains unchanged, it is possible to reduce the size of the valve
timing adjuster in the radial direction.
[0065] Furthermore, for example, if the distance L2 of the first
embodiment is reduced as much as possible within a range that
achieves the substantial sealing performance of hydraulic oil
between the slidably contacting surface 41 and the outer wall of
the hub portion 21, it is possible to reduce the size of the valve
timing adjuster in the longitudinal direction.
[0066] Also, for example, even in a condition, where the phase
changeable angle .theta.1 of the first embodiment remains unchanged
and the size of the valve timing adjuster remains unchanged, it is
possible to increase the torque of the valve timing adjuster
through increasing the number of vanes by an amount correspondingly
to an amount, by which the dimension of the shoe 14 in the
circumferential direction is reduced.
[0067] In the present embodiment, both of the advance passages and
the retard passages are provided to the vane rotor 20, and
accordingly, all the supply passages are intensively formed on one
component (or vane rotor). As a result, the configurations of the
supply passages are effectively simplified, and thereby the man
hour of machining or processing the component is effectively
reduced. Also, because the supply passages are not provided to the
rear plate, but to the vane rotor, it is possible to limit the
leakage of working fluid from the supply passages to the advance
chambers or to the retard chambers through the clearance between
the vane rotor and the rear plate.
Second Embodiment
[0068] FIG. 6 shows only a shoe and a part of the peripheral wall
around the shoe of a valve timing adjuster according to the second
embodiment of the present invention. The second embodiment is a
modification of the first embodiment.
[0069] In the present embodiment, the retard groove 610 and the
advance groove 650 are provided to the slidably contacting surface
41 to extend in the circumferential direction but not in the
longitudinal direction. Specifically, the retard groove 610 does
not open to the wall surface 181 of the shoe 14 adjacent the front
plate 18. However, the retard groove 610 opens only to the wall
surface 145 of the shoe 14 adjacent the retard chamber 51. Also,
the advance groove 65 does not open to the wall surface 111 of the
shoe 14 adjacent the rear plate 11. However, the advance groove 65
opens only to the wall surface 146 of the shoe 14 adjacent the
advance chamber 55.
[0070] In the present embodiment, the retard groove 610 and the
advance groove 650 may be relatively easily formed by cutting off
the slidably contacting surface 41 in the circumferential direction
through a method, such as milling. By forming the retard groove 610
and the advance groove 650 as above, it is possible to reduce the
man hour of the processing the product.
Third Embodiment
[0071] A valve timing adjuster 103 according to the third
embodiment of the present invention is shown in FIGS. 7 to 10. In
the present embodiment, retard grooves 71 to 74 and advance grooves
75 to 78 are formed at the outer wall of the hub portion 21.
[0072] FIG. 9 shows only the vane rotor 20 of the valve timing
adjuster 103, and FIG. 10 shows a view of the vane rotor 20
observed in a direction X in FIG. 9. FIG. 10 shows two vanes 25, 26
and a part of the outer wall the hub portion 21 around the vanes
25, 26.
[0073] It should be noted that in FIG. 10, positions of both ends
431, 432 of the slidably contacting surface 43 of the shoe 16 are
indicated by dashed lines when the phase of the vane rotor 20
relative to the housing 12 is controlled to the full advance
position.
[0074] A retard groove 73 is provided on one longitudinal side of
the outer wall of the hub portion 21, and an advance groove 77 is
provided on the other longitudinal side of the outer wall of the
hub portion 21 opposite from the one longitudinal side.
Specifically, the retard groove 73 opens to a wall surface 182 of
the hub portion 21 adjacent the front plate 18, and extends to a
boundary line 250 between the hub portion 21 and the vane 25. The
advance groove 77 opens to a wall surface 112 of the hub portion 21
adjacent the rear plate 11, and extends to a boundary line 260
between the hub portion 21 and the other vane 26. As above, the
retard groove 73 and the advance groove 77 are provided at the
outer wall of the hub portion 21 diagonally relative to each
other.
[0075] Another comparison example will be described. In the
comparison example, the retard groove and the advance groove are
provided to the hub portion to extend over a length of the hub
portion in the longitudinal direction. Thus, the retard groove and
the advance groove are formed to extend from the front plate side
to the rear plate side. The above configuration shortens a
distance, which is measured between the retard groove and the end
portion of the slidably contacting surface of the shoe in the
circumferential direction when the phase is controlled to the full
advance position. As a result, the area of the slidably contacting
surface becomes smaller, and thereby the sealing performance
deteriorates. Thereby, a distance L7, which is diagonally measured
between the retard groove 73 and an end portion 432 of the slidably
contacting surface 43, of the valve timing adjuster 103 according
to the third embodiment is longer than the above circumferential
distance of the comparison example. Due to the above configuration,
it is possible to increase the area of the slidably contacting
surface 43, and thereby it is possible to limit the leakage of
hydraulic oil between (a) the retard chamber 53, which is defined
between the vane 25 and the shoe 16, and (b) the advance chamber
57, which is defined between the vane 26 and the shoe 16.
[0076] In the present embodiment, the retard grooves 71 to 74 and
the advance grooves 75 to 78 are diagonally provided relative to
each other at positions on the outer wall of the hub portion 21
between the vanes 14 to 17. As a result, the sealing performance
between the slidably contacting surfaces 41 to 44 and the outer
wall of the hub portion 21 is effectively improved. Furthermore, in
the valve timing adjuster 10 of the present embodiment 3, the
distance L7, which is diagonally measured between the retard groove
73 and the end portion 432 of the slidably contacting surface 43,
is made longer than the distance L2, which is diagonally measured
between the retard groove 61 and the advance groove 65 in the first
embodiment. As a result, in the valve timing adjuster 10 of the
present embodiment 3, it is possible to furthermore improve the
sealing performance between the slidably contacting surfaces 41 to
44 and the outer wall of the hub portion 21 compared with the first
embodiment. Thereby, it is possible to effectively enlarge the
phase changeable angle, and effectively reduce the size of the
valve timing adjuster.
Fourth Embodiment
[0077] FIG. 11 shows only a vane rotor of a valve timing adjuster
according to the fourth embodiment of the present invention. The
fourth embodiment is a modification of the third embodiment.
[0078] In the present embodiment, a retard groove 730 and an
advance groove 770 are formed on the outer wall of the hub portion
21 to extend in the circumferential direction instead of in the
longitudinal direction. More specifically, the retard groove 730
extends to a position near the boundary line 250 between the hub
portion 21 and the vane 25. Also, the retard groove 730 does not
open to the wall surface 182 of the hub portion 21 adjacent the
front plate 18. Similarly, the advance groove 770 extends to a
position near the boundary line 260 between the hub portion 21 and
the vane 26. Also, the advance groove 770 does not open to the wall
surface 112 of the hub portion 21 adjacent the rear plate 11.
[0079] In the present embodiment, the retard groove 730 and the
advance groove 770 may be formed by cutting off the outer wall of
the hub portion 21 in the circumferential direction through a
method, such as milling. By forming the retard groove 730 and the
advance groove 770 as above, the man hour of processing the product
is effectively reduced.
Other Embodiment
[0080] In the above embodiments, the valve timing adjuster controls
the intake valve of the internal combustion engine. However, the
present invention may be applicable to a valve timing adjuster that
controls an exhaust valve of the internal combustion engine.
[0081] In the above embodiments, the front plate 18 and the rear
plate 11 are formed separately from the peripheral wall 13 of the
housing 12 and from the shoes 14 to 17. However, in another
embodiment of the present invention, the peripheral wall, the
shoes, the front plate, and the rear plate are all integrated with
each other.
[0082] Also, in the above embodiments, the gear 113 is provided to
the rear plate 11 at a position radially outward of the rear plate
11. However, in another embodiment of the present invention, the
gear may be provided at a position radially outward of the
peripheral wall of the housing or of the front plate.
[0083] As above, the present invention is not limited to the above
embodiments, and thereby the present invention may be modified in
various manners provided that the modification does not deviate
from gist and the scope of the present invention.
[0084] Additional advantages and modifications will readily occur
to those skilled in the art. The invention in its broader terms is
therefore not limited to the specific details, representative
apparatus, and illustrative examples shown and described.
* * * * *