U.S. patent application number 09/957508 was filed with the patent office on 2002-04-04 for variable valve timing system.
Invention is credited to Kanada, Yoji, Komazawa, Osamu.
Application Number | 20020038637 09/957508 |
Document ID | / |
Family ID | 18772810 |
Filed Date | 2002-04-04 |
United States Patent
Application |
20020038637 |
Kind Code |
A1 |
Kanada, Yoji ; et
al. |
April 4, 2002 |
Variable valve timing system
Abstract
A variable valve timing system includes a first controlling
mechanism through which operation fluid is supplied to and
discharged from an advanced angle chamber to restrict the relative
rotation to an advanced angle side at the lock phase, and a second
controlling mechanism through which operation fluid is supplied to
and discharged from a retarded angle chamber to restrict the
relative rotation to a retarded angle side at the lock phase. The
variable valve timing system further includes passages which
function as a throttle at the lock phase to connect the advanced
angle chamber with the first controlling mechanism and the retarded
angle chamber with the second controlling mechanism.
Inventors: |
Kanada, Yoji; (Gamagori-shi,
JP) ; Komazawa, Osamu; (Chita-shi, JP) |
Correspondence
Address: |
Platon N. Mandros, Esquire
BURNS, DOANE, SWECKER & MATHIS, L.L.P.
P.O. Box 1404
Alexandria
VA
22313-1404
US
|
Family ID: |
18772810 |
Appl. No.: |
09/957508 |
Filed: |
September 21, 2001 |
Current U.S.
Class: |
123/90.15 ;
123/90.17 |
Current CPC
Class: |
F01L 2001/0476 20130101;
F01L 2001/34476 20130101; F01L 1/3442 20130101; F01L 2001/34483
20130101 |
Class at
Publication: |
123/90.15 ;
123/90.17 |
International
Class: |
F01L 001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 22, 2000 |
JP |
2000-289400 |
Claims
What is Claimed is:
1. A variable valve timing system comprising: a housing member
rotatable as a unit with either a crankshaft or a camshaft of an
internal combustion engine; a rotor member relatively rotatably
assembled on a shoe portion of the housing member and forming an
advanced angle chamber and a retarded angle chamber at a vane
portion in the housing member, said rotor member rotating as a unit
with either the crankshaft or the camshaft of the internal
combustion engine; a relative rotation controlling mechanism
allowing relative rotation of the housing member and the rotor
member by an unlock operation through supply of an operation fluid,
and restricting relative rotation of the housing member and the
rotor member by a lock operation through discharge of the operation
fluid at a lock phase within an intermediate area from a most
advanced angle phase to a most retarded angle phase excluding
rotation limited phases of both ends; a fluid pressure circuit for
controlling the operation fluid to be supplied to and discharged
from the advanced angle chamber, the retarded angle chamber, and
the relative rotation controlling mechanism; the relative rotation
controlling mechanism being formed with a first controlling
mechanism restricting the relative rotation to an advanced angle
side when the first controlling mechanism is operated under the
lock operation at the lock phase, and a second controlling
mechanism restricting the relative rotation to a retarded angle
side when the second controlling mechanism is operated under the
lock operation at the lock phase; the fluid pressure circuit
supplying and discharging the operation fluid to or from the
advanced angle chamber through the first controlling mechanism, and
supplying and discharging the operation fluid to or from the
retarded angle chamber through the second controlling mechanism; a
first passage connecting the advanced angle chamber with the first
controlling mechanism and functioning as a throttle; and a second
passage connecting the retarded angle chamber with the second
controlling mechanism and functioning as a throttle.
2. The variable valve timing system according to claim 1, wherein
the throttle function of the first passage is canceled when the
rotor member is rotated relative to the housing member to the
advanced angle side from the lock phase by more than a
predetermined amount, and the throttle function of the second
passage is canceled when the rotor member is rotated relative to
the housing member to the retarded angle side from the lock phase
by more than the predetermined amount.
3. The variable valve timing system according to claim 1, wherein
each of the first and second controlling mechanisms includes a
spring and a lock plate slidably positioned in a radially directed
retracting groove formed in the housing member.
4. The variable valve timing system according to claim 3, wherein
each lock plate includes an end portion slidably positionable in a
respective lock groove formed in the rotor member.
5. The variable valve timing system according to claim 4, wherein
one of the lock grooves has a sloping bottom surface extending from
a deepest portion and becoming more shallow towards the retarded
angle side, the other lock groove having a sloping bottom surface
extending from a deepest portion and becoming more shallow towards
the advancing angle side.
6. The variable valve timing system according to claim 4, wherein
each of the lock grooves has a sloping bottom surface extending
from a deepest portion, the deepest portion of each lock groove
being positioned in opposition to the respective retracting grooves
when the rotor member is positioned at the lock phase relative to
the housing member.
7. The variable valve timing system according to claim 4, wherein
the first passage connects one of the lock grooves t o the advanced
angle chamber and the second passage connects the other lock groove
to the retarded angle chamber.
8. A variable valve timing system comprising: a housing member
rotating as a unit with either a crankshaft or a camshaft of an
internal combustion engine; a rotor member relatively rotatably
assembled on a shoe portion of the housing member and forming an
advanced angle chamber and a retarded angle chamber at a vane
portion in the housing member, said rotor member rotating as a unit
with either the crankshaft or the camshaft of the internal
combustion engine; a relative rotation controlling mechanism
allowing relative rotation of the housing member and the rotor
member by an unlock operation through supply of an operation fluid,
and restricting the relative rotation of the housing member and the
rotor member by a lock operation through the discharge of the
operation fluid at a lock phase within an intermediate area from a
most advanced angle phase to a most retarded angle phase excluding
rotation limited phase at both ends; a fluid pressure circuit
controlling the operation fluid to be supplied to and discharged
from the advanced angle chamber, the retarded angle chamber, and
the relative rotation controlling mechanism; the relative rotation
controlling mechanism comprising a first controlling mechanism
restricting the relative rotation to an advanced angle side when
the first controlling mechanism is operated under the lock
operation at the lock phase, and a second controlling mechanism
restricting the relative rotation to a retarded angle side when the
second controlling mechanism is operated under the lock operation
at the lock phase; the fluid pressure circuit supplying and
discharging the operation fluid to or from the advanced angle
chamber through the first controlling mechanism, and supplying and
discharging the operation fluid to or from the retarded angle
chamber through the second controlling mechanism; a first passage
having a first narrow portion which communicates between the
advanced angle chamber and the first controlling mechanism; and a
second passage having a second narrow portion which communicates
between the retarded angle chamber and the second controlling
mechanism.
9. The variable valve timing system according to claim 8, further
comprising: a first wide portion disposed next to the first narrow
portion; a second wide portion disposed next to the second narrow
portion; the first narrow portion being disposed a predetermined
distance toward the advanced angle side; and the second narrow
portion being disposed a predetermined distance toward the retarded
angle side.
10. The variable valve timing system according to claim 8, wherein
the first passage also includes a first wide portion disposed in
series with the first narrow portion in a peripheral direction of
the rotor member, the first wide portion having a greater
cross-sectional area than the first narrow portion.
11. The variable valve timing system according to claim 8, wherein
the second passage also includes a second wide portion disposed in
series with the second narrow portion in a peripheral direction of
the rotor member, the second wide portion having a greater
cross-sectional area than the second narrow portion.
12. The variable valve timing system according to claim 8, wherein
each of the first and second controlling mechanisms includes a
spring and a lock plate slidably positioned in a radially directed
retracting groove formed in the housing member.
13. The variable valve timing system according to claim 12, wherein
each lock plate includes an end portion slidably positionable in a
respective lock groove formed in the rotor member.
14. The variable valve timing system according to claim 13, wherein
one of the lock grooves has a sloping bottom surface extending from
a deepest portion and becoming more shallow towards the retarded
angle side, the other lock groove having a sloping bottom surface
extending from a deepest portion and becoming more shallow towards
the advancing angle side.
15. The variable valve timing system according to claim 13, wherein
each of the lock grooves has a sloping bottom surface extending
from a deepest portion, the deepest portion of each lock groove
being positioned in opposition to the respective retracting grooves
when the rotor member is positioned at the lock phase relative to
the housing member.
16. The variable valve timing system according to claim 13, wherein
the first passage connects one of the lock grooves to the advanced
angle chamber and the second passage connects the other lock groove
to the retarded angle chamber.
Description
[0001] This application is based on and claims priority under 35
U.S.C. .sctn. 119 with respect to Japanese Application 2000-289400
filed on Sep. 22, 2000, the entire content of which is incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] This invention generally relates to a variable valve timing
system of an internal combustion engine. More particularly, the
present invention pertains to a variable valve timing system for
controlling the opening and closing timing of an intake valve and
an exhaust valve in an internal combustion engine.
BACKGROUND OF THE INVENTION
[0003] A known variable valve timing system is disclosed in
Japanese Patent Laid-Open Publication No. 09(1997) 324613 published
on Dec. 16, 1997. The disclosed variable valve timing system
includes a housing member rotating as a unit with either a
crankshaft or a camshaft of the internal combustion engine, and a
rotor member rotating as a unit with either the camshaft or
crankshaft. The rotor member is rotatably assembled on a shoe
portion provided at the housing member and forms an advanced angle
chamber and a retarded angle chamber at a vane portion in the
housing member. The variable valve timing system also includes a
relative rotation controlling mechanism which allows relative
rotation of the housing member and the rotor member by an unlock
operation the supply of an operation fluid. The relative rotation
controlling mechanism also restricts relative rotation of the
housing member and the rotor member by a lock operation through the
discharge of the operation fluid at a lock phase within an
intermediate area from a most advanced angle phase to a most
retarded angle phase excluding rotation limited phases at both
ends. The variable valve timing system further includes a fluid
pressure circuit for controlling the operation fluid to be supplied
to and discharged from the advanced angle chamber, the retarded
angle chamber, and the relative rotation controlling mechanism.
[0004] In the above-mentioned variable valve timing system, the
passage connecting the advanced angle chamber and the relative
rotation controlling mechanism with the fluid pressure circuit, and
the passage connecting the retarded angle chamber and the relative
rotation controlling mechanism with the fluid pressure circuit
always communicate under the same condition. The fluid pressure of
the operation fluid supplied to the advanced angle chamber and the
relative rotation controlling mechanism, or the fluid pressure of
the operation fluid supplied to the retarded angle chamber and the
relative rotation controlling mechanism are each approximately the
same pressure all the time. Accordingly, when the relative rotation
of the rotor member and the housing member is restricted at the
lock phase by the relative rotation controlling mechanism, when the
operation fluid is rapidly supplied (phase control for quick
response) to the advanced angle chamber through the relative
rotation controlling mechanism or to the retarded angle chamber
through the relative rotation controlling mechanism both from the
fluid pressure circuit, the relative rotation of the rotor member
and the housing member is started before the unlock operation of
the relative rotation controlling mechanism is completed. Thus a
lock member of the relative rotation controlling mechanism can be
caught in the relative rotation of the rotor member and the housing
member.
[0005] Additionally, in the above-mentioned variable valve timing
system, the rotor member is rotated by the fluctuation torque of
the camshaft in the lock phase, and the pressure of the operation
fluid filled in the advanced angle chamber or the retarded angle
chamber is increased because the volume of the advanced angle
chamber or the retarded angle chamber becomes smaller by the
rotation of the vanes. The increased pressure of the operation
fluid causes movement of the lock member (unlock operation) and
unintended operation of the relative rotation controlling
mechanism.
[0006] In light of the foregoing, a need exists for an improved
variable valve timing system which is not as susceptible to the
drawbacks discussed above.
SUMMARY OF THE INVENTION
[0007] According to one aspect of the invention, a variable valve
timing system includes a housing member rotatable as a unit with
either a crankshaft or a camshaft of an internal combustion engine,
and a rotor member relatively rotatably assembled on a shoe portion
of the housing member and forming an advanced angle chamber and a
retarded angle chamber at a vane portion in the housing member,
with the rotor member rotating as a unit with either the crankshaft
or the camshaft of the internal combustion engine. A relative
rotation controlling mechanism allows relative rotation of the
housing member and the rotor member by an unlock operation through
supply of an operation fluid, and restricts relative rotation of
the housing member and the rotor member by a lock operation through
discharge of the operation fluid at a lock phase within an
intermediate area from a most advanced angle phase to a most
retarded angle phase excluding rotation limited phases at both
ends. A fluid pressure circuit controls the operation fluid to be
supplied to and discharged from the advanced angle chamber, the
retarded angle chamber, and the relative rotation controlling
mechanism. The relative rotation controlling mechanism includes a
first controlling mechanism restricting the relative rotation to an
advanced angle side when the first controlling mechanism is
operated under the lock operation at the lock phase, and a second
controlling mechanism restricting the relative rotation to a
retarded angle side when the second controlling mechanism is
operated under the lock operation at the lock phase. The fluid
pressure circuit supplies and discharges the operation fluid to or
from the advanced angle chamber through the first controlling
mechanism, and supplies and discharges the operation fluid to or
from the retarded angle chamber through the second controlling
mechanism. A first passage connects the advanced angle chamber with
the first controlling mechanism and functions as a throttle, and a
second passage connects the retarded angle chamber with the second
controlling mechanism and functions as a throttle.
[0008] When used in a variable valve timing system for an
automobile, the throttle function of the advanced angle side and
the retarded angle side is desirably canceled when the rotor member
is rotated relative to the housing member to the advanced angle
side or the retarded angle side from the lock phase by more than a
predetermined amount.
[0009] At an early stage of starting of the internal combustion
engine, the operation fluid is not sufficiently discharged from the
fluid pressure circuit to each advanced angle chamber, each
retarded angle chamber, the first controlling mechanism, and the
second controlling mechanism. Thus, the relative rotation phase of
the rotor member to the housing member cannot be adjusted or
maintained. If the relative rotation phase of the rotor member to
the housing member is not positioned at the intermediate lock
phase, the housing member and the rotor member are relatively
rotated by torque fluctuation affecting the camshaft. In this
manner, when the relative rotation phase of the rotor member to the
housing member is positioned at the intermediate lock phase, the
relative rotation to the advanced angle side is restricted by the
first controlling mechanism, and the relative rotation to the
retarded angle side is restricted by the second controlling
mechanism. Then the relative rotation of the housing member and the
rotor member is restricted and maintained at the intermediate lock
phase by the first controlling mechanism and the second controlling
mechanism, and the starting performance of the internal combustion
engine is improved.
[0010] As explained above, when relative rotation of the housing
member and the rotor member is restricted by the first controlling
mechanism and the second controlling mechanism at the intermediate
lock phase, when the operator fluid is sufficiently supplied to
each advanced angle chamber through the first controlling mechanism
from the fluid pressure circuit, or to each retarded angle chamber
through the second controlling mechanism from the fluid pressure
circuit, the first passage connecting the advanced angle chamber
which the first controlling mechanism functions as a throttle and
the second passage connecting the retarded angle chamber with the
second controlling mechanism also functions as a throttle.
[0011] Accordingly, in the passages to which the operation fluid is
supplied, the fluid pressure provided to the first controlling
mechanism or the second controlling mechanism is instantly
obtained, and the unlock operation is immediately conducted. At the
same time, the supply of operation fluid is controlled to the
advanced angle chamber and the retarded angle chamber by the
throttle function of both passages. Then the relative rotation of
the housing member and the rotor member is relatively slower
compared to the unlock operation. Thus, when the phase is
controlled for quick response, the lock members of the first
controlling mechanism and the second controlling mechanism cannot
be caught in the relative rotation of the housing member and the
rotor member.
[0012] When the rotor member is rotated to the advanced angle side
or the retarded angle side from the lock phase relative to the
housing member by more than the predetermined amount, the throttle
function of the advanced angle side and the retarded angle side is
configured to be canceled. Thus at the lock phase, the throttle
function is effectively operated, and when the rotor member is
rotated relative to the housing member to the advanced angle side
or the retarded angle side from the lock phase by more than the
predetermined amount, the operation fluid is thoroughly supplied to
the advanced angle chamber from the first controlling mechanism or
to the retarded angle chamber from the second controlling
mechanism. Then the rotor member is relatively rotated to the
housing member with a good response. Accordingly, a reliable or
certain unlock operation and good response can be obtained.
[0013] According to another aspect of the invention, a variable
valve timing system includes a housing member rotatable as a unit
with either a crankshaft or a camshaft of an internal combustion
engine, and a rotor member relatively rotatably assembled on a shoe
portion of the housing member and forming an advanced angle chamber
and a retarded angle chamber at a vane portion in the housing
member, with the rotor member rotating as a unit with either the
crankshaft or the camshaft of the internal combustion engine. A
relative rotation controlling mechanism allows relative rotation of
the housing member and the rotor member by an unlock operation
through supply of an operation fluid, and restricts relative
rotation of the housing member and the rotor member by a lock
operation through discharge of the operation fluid at a lock phase
within an intermediate area from a most advanced angle phase to a
most retarded angle phase excluding rotation limited phases at both
ends. A fluid pressure circuit controls the operation fluid to be
supplied to and discharged from the advanced angle chamber, the
retarded angle chamber, and the relative rotation controlling
mechanism. The relative rotation controlling mechanism includes a
first controlling mechanism restricting the relative rotation to an
advanced angle side when the first controlling mechanism is
operated under the lock operation at the lock phase, and a second
controlling mechanism restricting the relative rotation to a
retarded angle side when the second controlling mechanism is
operated under the lock operation at the lock phase. The fluid
pressure circuit supplies and discharges the operation fluid to or
from the advanced angle chamber through the first controlling
mechanism, and supplies and discharges the operation fluid to or
from the retarded angle chamber through the second controlling
mechanism. A first passage having a first narrow portion
communicates between the advanced angle chamber and the first
controlling mechanism, and a second passage having a second narrow
portion communicates between the retarded angle chamber and the
second controlling mechanism.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0014] The foregoing and additional features and characteristics of
the present invention will become more apparent from the following
detailed description considered with reference to the accompanying
drawing figures in which like reference numerals designate like
elements and wherein:
[0015] FIG. 1 is a schematic illustration of a variable valve
timing system according to an embodiment of the present
invention;
[0016] FIG. 2 is a cross-sectional view of a portion of the
variable valve timing system shown in FIG. 1 viewed from the
front;
[0017] FIG. 3 is a cross-sectional view of a portion of the
variable valve timing system shown in FIG. 2 illustrating the
structure of a passage connecting the first control mechanism with
the advanced angle chamber;
[0018] FIG. 4 shows an operational position of the main rotor shown
in FIG. 2 in which the main rotor is rotated a predetermined amount
relative to a housing body to the advanced angle side from an
intermediate lock phase; and
[0019] FIG. 5 shows an operational position of the main rotor shown
in FIG. 2 in which the main rotor is rotated a predetermined amount
relative to a housing body to the retarded angle side from an
intermediate lock phase.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Referring initially to FIGS. 1 and 2, the variable valve
timing system in accordance with the present invention includes a
rotor member 20 assembled as a unit with an end portion (left side
in FIG. 1) of a cam shaft 10 in an internal combustion engine, and
a housing member 30 supported by the rotor member 20 for rotation
within a predetermined range. The variable valve timing system also
includes a torsion spring S disposed between the housing member 30
and the rotor member 20, and a first controlling mechanism B1 and a
second controlling mechanism B2 forming a relative rotation
controlling mechanism for restricting relative rotation of the
housing member 30 and the rotor member 20. The variable valve
timing system further includes a fluid pressure circuit C for
controlling operation fluid to be supplied to and discharged from
the first controlling mechanism B1 and the second controlling
mechanism B2. The fluid pressure circuit C also controls operation
fluid to be supplied to or discharged from advanced angle chambers
R1 and retarded angle chambers R2, the details of which will be
described below.
[0021] The camshaft 10 having a known cam for controlling the
opening and closing of an intake valve is rotatably supported by a
cylinder head 40 of the internal combustion engine. An advanced
angle passage 11 and a retarded angle passage 12 are provided in
the camshaft 10 and extend in the axial direction. The advanced
angle passage 11 is connected with a connecting port 102 of a fluid
pressure controlling valve 100 through a radially extending passage
13 and an annular passage 14. The retarded angle passage 12 is
connected with a connecting port 101 of the fluid pressure
controlling valve 100 through a radially extending passage 15 and
an annular passage 16. The radially extending passages 13, 15 and
the annular passage 16 are formed in the camshaft 10 and the
annular passage 14 is formed in a stepped portion between the
camshaft 10 and the cylinder head 40.
[0022] The rotor member 20 includes a main rotor 21 and a front
rotor 22 which is assembled on the front of the main rotor 21
(i.e., the left side of the main rotor 21 in FIG. 1) as a unit and
has a cylindrical shape with a stepped portion. The rotor member 20
is engaged with or connected to the front end of the camshaft 10 as
a unit by a bolt 50. The central inner bores of the main motor 21
and the front rotor 22 are connected with the advanced angle
passage 11 provided in the camshaft 10 being blocked by a head
portion of the bolt 50 at the front end.
[0023] The main rotor 21 is provided with an inner bore 21a
coaxially assembled with the front rotor 22, and four vane grooves
21b for receiving respective vanes 23 and for assembling a spring
24 (shown in FIG. 1) biasing the four vanes 23 outward in the
radial direction. Each vane 23 assembled in the respective vane
groove 21b extends outwardly in the radial direction and divides
respective spaces in the housing member 30 into one of the advanced
angle chambers R1 and one of the retarded angle chambers R2.
[0024] The main rotor 21 includes three passages 21c extending
generally in the radial direction which communicate with the
advance angle passage 11 at the radial inner end through the
central inner bore and communicate with a respective one of the
advanced angle chambers R1 at the radial outer end. The main rotor
21 also includes a radially extending passage 21d in communication
with the advanced angle passage 11 at the radial inner end through
the central inner bore and in communication with one of the
advanced angle chambers R1 at the radial outer end through the
first controlling mechanism B1 and a passage P1.
[0025] The main rotor 21 further include four axially extending
passages 21e in communication with the retarded angle passage 12,
three radially extending passages 21f each communicating with one
of the respective passages 21e at the radial inner end and
communicating with one of the respective retarded angle chambers R2
at the radial outer end. Moreover, the main rotor 21 includes a
passage 21g in communication with one of the passages 21e at the
radial inner end and in communication with one of the retarded
angle chambers R2 at the radial outer end through the second
controlling mechanism B2 and a passage P2.
[0026] The housing member 30 is provided with a housing body 31, a
front plate 32, and a rear thin plate 33. Four bolts 34 which are
shown in FIG. 2 connect the housing body 31, the front plate 32 and
the rear thin plate 33 as a unit. The outer periphery of the
housing body 31 is provided with a sprocket 31a. The sprocket 31a
is connected to a crankshaft of the internal combustion engine
through a timing chain and is rotated in the clockwise direction in
FIG. 2 by the driving force transmitted from the crankshaft.
[0027] The housing body 31 is provided with four shoe portions 31b
projecting inward in the radial direction and rotatably supporting
the main rotor 21 at the radial inner end of each shoe portion 31b.
The axially opposing end surfaces of the front plate 32 and the
rear thin plate 33 are slidably in contact with the outer
peripheral end surfaces of the main rotor 21 and the end surfaces
of the vanes 23. As shown in FIG. 2, the housing body 31 is also
provided with a projection 31c defining the most retarded angle
phase and a projection 31d defining the most advanced angle phase
through contact with the vanes 23.
[0028] Through unlock operation of the first controlling mechanism
B1 by the supply of the operation fluid from the advanced angle
passage 11, the relative rotation of the housing member 30 and the
rotor member 20 is allowed. Also, through the lock operation of the
first controlling mechanism B1 by the discharge of the operation
fluid to the advanced angle passage 11, the relative rotation of
the housing member 30 and the rotor member 20 to the advanced angle
side is restricted at the intermediate lock phase (the condition
shown in FIG. 2) between the most advanced angle phase and the most
retarded angle phase. The first controlling mechanism B1 includes a
lock plate 61 and a lock spring 62.
[0029] The lock plate 61 is slidably movable in the radial
direction within a radial retracting groove 31e formed in the
housing body 31. The lock plate 61 is biased to be projected from
the retracting groove 31e by the lock spring 62 accommodated in a
receiving portion 31f of the housing body 31. The receiving portion
31f of the housing body 31 is atmospherically open through an open
bore (not shown) provided at the rear thin plate 33. Accordingly,
smooth movement of the lock plate 61 in the radial direction is
assured.
[0030] The end portion or radial inner end of the lock plate 61 is
slidably and detachably (i.e., can be disposed and detached)
supported in a lock groove 21h formed in the main rotor 21. By the
supply of the operation fluid to the lock groove 21h, the lock
plate 61 is moved in the radial direction and received in the
retracting groove 31e by overcoming the biasing force
(predetermined as a small value) of the lock spring 62. The end
portion of the lock plate 61 can be in contact with a bottom
surface of the lock groove 21h or the outer periphery of the main
rotor 21, and is slidably movable in the peripheral direction under
the contacting condition.
[0031] When the rotor member 20 is positioned at the intermediate
lock phase relative to the housing member 30 as shown in FIG. 2,
the deepest end portion (the advanced angle side) of the lock
groove 21h is opposed to the retracting groove 31e. The bottom
surface of the lock groove 21h becomes gradually shallower and is
sloped toward the retarded angle side, and the axial end portion of
the lock groove 21h is formed with a recess potion 21i where the
operation fluid can be stored. Because the bottom portion of the
lock groove 21h is sloped (toward the radial outer direction from
the radial inner direction), the lock plate 61 runs on the outer
periphery of the main rotor 21 and is slidably moved thereon.
Accordingly, the movement amount of the lock plate 61 in peripheral
direction relative to the displacement amount of the rotor member
20 can be assured without the lock groove 21h being extended in the
peripheral direction. The area of the advanced angle chambers R1
and the area of the retarded angle chambers R2 can be larger and
also the displacement amount (displacement angle) of the vanes 23
can be larger. The lock groove 21h is in communication with the
advanced angle passage 11 through the radially extending passage
21d and is in communication with the advanced angle chamber R1
through the peripherally extending passage P1.
[0032] When the rotor member 20 is rotated from the intermediate
lock phase as shown in FIG. 2 to the most retarded angle phase or
to the advanced angle side relative to the housing member 30 with a
predetermined amount, the lock groove 21h and the advanced angle
chamber R1 are connected to each other through the passage P1. As
shown in FIGS. 2 and 3, the passage P1 is provided with a small
notch 21j and a large notch 21k in series in the peripheral
direction and formed on the outer end periphery in the axial
direction of the main rotor 21. The small notch 2lj functions as a
throttle while the rotor member 20 is rotated to the advanced angle
side from the intermediate lock phase relative to the housing
member 30 over the predetermined amount. In this condition, the
advanced angle chamber R1 communicates with the passage 21d and the
lock groove 21h via the small notch 21j only. The quantity of
operation fluid supplied to the advance angle chamber R1 is limited
by the small notch 21j. Because the cross-sectional area of the
small notch 21j is smaller than the cross-sectional area of the
passage 21d, the small notch 2lj operates like an orifice.
Therefore, the small notch 21j functions as a throttle. When the
rotor member 20 is relatively rotated to the advanced angle side
more than the predetermined amount, the throttle function of the
small notch 2lj is canceled. That is, the small notch 2lj is no
longer connected with the shoe portion 31b and so the lock groove
21h is directly in communication with the advanced angle chamber
R1, or the advanced angle chamber R1 communicates with the passage
21d and the lock groove 21 via the large notch 21k.
[0033] With the unlock operation of the second controlling
mechanism B2 through the supply of the operation fluid from the
retarded angle passage 12, the relative rotation of the housing
member 30 and rotor member 20 is allowed. Also with the lock
operation of the second controlling mechanism B2 through the
discharge of operation fluid to the retarded angle passage 12, the
relative rotation of the housing member 30 and the rotor member 20
to the retarded angle side is restricted at the intermediate lock
phase (the condition shown in FIG. 2) between the most advanced
angle phase and the most retarded angle phase. The second
controlling mechanism B2 includes a lock plate 63 and a lock spring
64.
[0034] The lock plate 63 is slidable movable in the radial
direction within a radial retracting groove 31g formed in the
housing body 31. The lock plate 63 is biased to be projected from
the retracting groove 31g by the lock spring 64 accommodated in a
receiving portion 31h of the housing body 31. The receiving portion
31h of the housing body 31 is atmospherically open through an open
bore (not shown) provided at the rear thin plate 33. Accordingly,
smooth movement of the lock plate 63 in the radial direction is
assured.
[0035] The end portion or radial inner end of the lock plate 63 is
slidably and detachably (i.e., can be disposed in and detached
from) supported in a lock groove 21m formed in the main rotor 221.
Through the supply of the operation fluid to the lock groove 21m,
the lock plate 63 is moved in the radial direction and is received
in the retracting groove 31g by overcoming the biasing force
(predetermined as a small value) of the lock spring 64. The end
portion of the lock plate 63 can be in contact with the bottom
surface of the lock groove 21m or the outer periphery of the main
rotor 21, and is slidably movable in the peripheral direction under
the contacting condition.
[0036] When the rotor member 20 is positioned at the intermediate
lock phase relative to the housing member 30 as shown in FIG. 2,
the deepest end portion (on the retarded angle side) of the lock
groove 21m is opposed to the retracting groove 31g. The bottom
surface of the lock groove 21m gets more shallow and is sloped
toward the advanced angle side, and the axial end portion of the
lock groove 21m is formed with a recess portion 21n where the
operation fluid can be stored. Because the bottom portion of the
lock groove 21m is sloped (toward the radial outer direction from
the radial inner direction), the lock plate 63 runs on or moves
along the outer periphery of the main rotor 21 and is slidably
moved thereon. Accordingly, the movement amount of the lock plate
63 can be assured in the peripheral direction relative to the
displacement amount of the rotor member 20 without the lock grove
21m being extended in the peripheral direction. The area of the
advanced angle chambers R1 and the area of the retarded angle
chambers R2 can be larger and also the displacement amount
(displacement angle) of the vanes 23 can be larger. The lock grove
21m is in communication with the retarded angle passage 12 through
the radially extending passage 21g and is in communication with the
retarded angle chamber R2 through the peripherally extending
passage P2.
[0037] When the rotor member 20 is rotated from the intermediate
lock phase as shown in FIG. 2 to the most advanced angle phase or
to the retarded angle side relative to the housing member 30 by the
predetermined amount, the lock groove 21m and the retarded angle
chamber R2 are connected each other through the passage P2. The
passage P2 is provided with a small notch 21p and a large notch 21q
arranged in series in the peripheral direction and formed on the
outer end periphery in the axial direction of the main rotor 21.
The small notch 21p functions as throttle while the rotor member 20
is rotated to the retarded angle side from the intermediate lock
phase relative to the housing member 30 by the predetermined
amount. When the rotor member 20 is relatively rotated to the
retarded angle side by more than the predetermine amount, the
throttle function of the small notch 21p is canceled. That is,
because the small notch 21p is no longer connected with the shoe
portion 31b, the lock groove 21m is directly in communication with
the retarded angle chamber R2.
[0038] The tension spring S disposed between the housing member 30
and the rotor member 20 rotatably biases the rotor member 20 to the
advanced angle side relative to the housing member 30. The biasing
force of the torsion spring S is predetermined to be of such an
amount as to cancel the force derived from a spring (not shown)
biasing the intake valve towards the closing position, which
eventually biases the camshaft 10 and the rotor member 20 towards
the retarded angle side. Thus, good response can be obtained when
the relative rotation phase of the rotor member 20 to the housing
member 30 is varied to the advanced angle side.
[0039] The fluid pressure controlling valve 100 shown in FIG. 1
comprises a part of the fluid pressure circuit C together with an
oil pump 110 and an oil reservoir 120 of the internal combustion
engine. A spool 104 can be moved left from the position in FIG. 1
against the force of a spring 105 by the energization of a solenoid
103 in response to an output signal from an energization
controlling device 200. By varying a duty value (%), the operation
fluid can be controlled to be supplied to or discharged from the
advanced angle passage 11, the retarded angle passage 12, the first
controlling mechanism B1, and the second controlling mechanism
B2.
[0040] The oil pump 110 is actuated by the internal combustion
engine, whereby the operation fluid is supplied to a supply port
106 of the fluid pressure controlling valve 100 from the oil
reservoir 120 of the internal combustion engine. The oil reservoir
120 of the internal combustion engine is connected with a discharge
port 107 of the fluid pressure controlling valve 100. The operation
fluid is thus returned from the discharge port 107 to the reservoir
120. The energization controlling device 200 controls the output
(duty value) based on detected signals from various sensors,
including sensors for detecting the crank angle, the cam angle, the
throttle opening degree, the engine rpm, the temperature of the
engine cooling water and the vehicle speed, in response to the
operation condition of the internal combustion engine by following
a predetermined controlling pattern.
[0041] According to the described embodiment of the variable valve
timing system of the present invention, when the internal
combustion engine is not operated, the operation fluid is returned
to the oil reservoir 120 of the internal combustion engine from
each advanced angle chamber R1, each retarded angle chamber R2, the
lock groove 21h of the first controlling mechanism B1, and the lock
groove 21m of the second controlling mechanism B2 through gaps
formed amongst the various members. At an early stage of the
internal combustion engine starting or operation, the operation
fluid is not sufficiently discharged even though the oil pump 110
is actuated by the internal combustion engine. Further, the
operation fluid is not sufficiently supplied to each advanced angle
chamber R1, each retarded angle chamber R2, the lock groove 21h of
the first controlling mechanism B1 and the lock groove 21m of the
second controlling mechanism B2 from the fluid pressure circuit C
even though the energization to the solenoid 103 of the fluid
pressure controlling valve 100 is controlled by the energization
controlling device 200. Accordingly, the relative rotation phase of
the rotor member 20 with respect to the housing member 30 cannot be
adjusted or maintained. If the relative rotation phase of the rotor
member 20 with respect to the housing member 30 is not the
intermediate lock phase, the housing member 30 and the rotor member
20 are relatively rotated by torque fluctuations affecting the
camshaft.
[0042] In this manner, when the relative rotation phase of the
rotor member 20 with respect to the housing member 30 is positioned
at the intermediate lock phase, the lock plate 61 of the first
controlling mechanism B1 is received in the lock groove 21h by the
biasing force of the lock spring 62. Then, relative rotation to the
advanced angle side is restricted. Also the lock plate 63 of the
second controlling mechanism B2 is received in the lock groove 21m
by the biasing force of the lock spring 64, and then relative
rotation to the retarded angle side is restricted. Accordingly,
relative rotation of the housing member 30 and the rotor member 20
is restricted and maintained at the intermediate lock phase by the
first controlling mechanism B1 and the second controlling mechanism
B2. Thus adequate variable valve timing is obtained for starting
the internal combustion engine, and the starting performance of the
internal combustion engine is improved.
[0043] With relative rotation of the rotor member 20 with respect
to the housing member 30 being restricted by the first controlling
mechanism B1 and the second controlling mechanism B2 at the
intermediate lock phase as explained above, when the operation
fluid is sufficiently supplied to each advanced angle chamber R1
through the first controlling mechanism B1 from the fluid pressure
circuit C, the passage P1 functions as a throttle connecting the
advanced angle chamber R1 with the first controlling mechanism B1.
In the same say and under the same condition, when the operation
fluid is sufficiently supplied to each retarded angle chamber R2
through the second controlling mechanism B2 from the fluid pressure
circuit C, the passage P2 functions as a throttle connecting the
retarded angle chamber R2 with the second controlling mechanism
B2.
[0044] Then first, in the passages P1, P2 to which the operation
fluid is supplied, the fluid pressure being provided for the first
controlling mechanism B1 and the second controlling mechanism B2 is
instantly obtained. Next, the unlock operation is immediately
conducted as the lock plates 61, 63 are retracted and received in
the retracting grooves 31e, 31g respectively by overcoming the
force of the respective lock springs 62, 64. By virtue of the
throttle function associated with the passage P1, P2, the supply of
operation fluid is controlled to the advanced angle chamber R1 and
the retarded angle chamber R2. The quantity of operation fluid
supplied to the advanced angle chamber R1 is decreased by the
throttling function of the passage P1 (the small notch 21j).
However, the quantity of operation fluid supplied to the lock
groove 21h is enough, and the lock plate 61 can move toward the
retracting groove 31e by the pressure of the operation fluid filled
in the lock groove 21h, so the first controlling mechanism is in
the unlock operation. After the unlock operation of the first
control mechanism, the operation fluid is filled into the advanced
angle chamber B1 so as to rotate the rotor member 21.
[0045] Similarly, the quantity of operation fluid supplied to the
retarded angle chamber R2 is decreased by the throttling function
of the passage P2 (the small notch 21p). However, the quantity of
operation fluid supplied to the lock groove 21m is enough, and the
lock plate 63 can move toward the retracting groove 31g by the
pressure of the operation fluid filled in the lock groove 21m, so
the second controlling mechanism is in the unlock operation. After
the unlock operation of the second control mechanism B2, the
operation fluid is filled to the retarded angle chamber R2 so as to
rotate the rotor member 21. Thus the relative rotation of the rotor
member 20 and the housing member 30 is relatively slower compared
to the unlock operation. Accordingly, when the phase is controlled
for quick response, the lock plate 61 of the first controlling
mechanism B1 and the lock plate 63 of the second controlling
mechanism B2 cannot be caught in the relative rotation of the rotor
member 20 and the housing member 30.
[0046] Under the condition above with the internal combustion
engine being started and when the rotor member 20 is rotated to the
advanced angle side or the retarded angle side from the
intermediate lock phase relative to the housing member 30 by more
than the predetermined amount as shown in FIGS. 4 and 5, the
throttling function of the passages P1, P2 of the advanced angle
side and the retarded angle side is canceled. Accordingly, when the
rotor member 20 is rotated to the advanced angle side or the
retarded angle side from the intermediate lock phase relative to
the housing member 30 by more than the predetermined amount, the
operation fluid is thoroughly supplied to the advanced angle
chamber R1 or the retarded angle chamber R2 from the first
controlling mechanism B1 or the second controlling mechanism B2 via
the large notches 21k, 21q and the lock grooves 21h, 21m, or via
the lock grooves 21, 21m directly. The cross-sectional area of the
passage becomes larger and the quantity of the operation fluid is
decreased. Then the rotor member 20 is rotated relative to the
housing member 30 with a good response. Accordingly, certain or
reliable unlock operation and good response can be obtained.
[0047] Meanwhile, when the internal combustion engine is under the
normal operation condition (i.e., excluding the starting
operation), the oil pump 110 is actuated by the internal combustion
engine and the operation fluid is sufficiently discharged. Then the
operation fluid is sufficiently supplied to each advanced angle
chamber R1, each retarded angle chamber R2, the lock groove 21h of
the first controlling mechanism B1, and the lock groove 21m of the
second controlling mechanism B2 through the fluid pressure circuit
C. Thus the rotation phase of the rotor member 20 relative to the
housing member 30 can be adjusted and maintained at a desired phase
within the range from the most retarded angle phase (the phase in
which the volume of the advanced angle chamber R1 is a minimum and
the volume of the retarded angle chamber R2 is a maximum) to the
most advanced angle phase (the phase in which the volume of the
advanced angle chamber R1 is a maximum and the volume of the
retarded angle chamber R2 is a minimum) through the energization of
the solenoid 103 of the fluid pressure controlling valve 100 being
controlled by the energization controlling device 200. Under the
normal operation condition of the internal combustion engine, the
variable valve timing of the intake valve can be appropriately
adjusted between the operation at the most retarded angle phase and
the operation at the most advanced angle phase.
[0048] In this case, the rotation phase of the rotor member 20 to
the advanced angle side relative to the housing member 30 is
adjusted by the supply of the operation fluid to each advanced
angle chamber R1 and the lock groove 21h of the first controlling
mechanism B1 through the fluid pressure controlling valve 100, and
by the discharge of the operation fluid from each retarded angle
chamber R2 and the lock groove 21m of the second controlling
mechanism B2 through the fluid pressure controlling valve 100.
[0049] At this time, under the following condition, the rotor
member 20 is rotated to the advanced angle side relative to the
housing member 30 because the operation fluid is supplied to each
advanced angle chamber R1 and the lock groove 21h, and is
discharged from each retarded angle chamber R2 and the lock groove
21m. The condition is that once the operation fluid is supplied to
the lock groove 21h of the first controlling mechanism B1, the lock
plate 61 is unlocked by overcoming the force of the lock spring 62
and is received in the retracting groove 31e, or is slidably in
contact with the outer periphery of the main rotor 21 (as shown in
FIG. 4). In addition, the lock plate 63 is slidably in contact with
the outer periphery of the main rotor 21 or is slidably in contact
with the bottom surface of the lock groove 21m (as shown in FIG.
4).
[0050] The rotation phase of the rotor member 20 to the retarded
angle side relative to the housing 30 is adjusted by the supply of
the operation fluid to each retarded angle chamber B2 and the lock
groove 21m of the second controlling mechanism 32 and by the
discharge of the operation fluid from each advanced angle chamber
R1 and the lock groove 21h of the first controlling mechanism B1
through the fluid pressure controlling valve 100.
[0051] At this time, under the following condition, the rotor
member 20 is rotated to the retarded angle side relative to the
housing member 30 because the operation fluid is supplied to each
retarded angle chamber R2 and the lock groove 21m, and is
discharged from each advanced angle chamber R1 and the lock groove
21h. The condition is that once the operation fluid is supplied to
the lock groove 21m of the second controlling mechanism B2, the
lock plate 63 is unlocked by overcoming the force of the lock
spring 64 and is received in the retracting groove 31g, or is
slidably in contact with the outer periphery of the main rotor 21
(as shown in FIG. 5). In addition, the lock plate 61 is slidably in
contact with the outer periphery of the main rotor 21 or is
slidably in contact with the bottom surface of the lock groove 21h
(as shown in FIG. 4).
[0052] In the embodiment of the variable valve timing system of the
present invention described above, the housing member 30 is
integrally rotated with the crankshaft, and the rotor member 20 is
integrally rotated with the camshaft 10. However, the present
invention has useful application to another type of variable valve
timing system in which the housing member is integrally rotated
with the camshaft and the rotor member is integrally rotated with
the crankshaft. The present invention can also be used in
connection with variable valve timing systems in which the vane is
formed as a unit with the rotor body.
[0053] In the lock phase, the torque fluctuation of the camshaft
rotates the rotor member 21, and the pressure of the operation
fluid filled in the advanced angle chamber R1, or the retarded
angle chamber R2, is increase because the volume of the advanced
angle chamber R1, or the retarded angle chamber R2, is made smaller
or reduced by the rotation of the vanes 23. The pressure of the
operation fluid causes movement (unlock operation) of the lock
member 31e, 31g because the advanced angle chamber R1 or the
retarded angle chamber R2 communicates with the lock groove 21h,
21m via the passage P1, P2 respectively. However, the throttling
function of the small notch 21j, 21p prevents the transmission of
the pressure. Therefore, the first and second control mechanisms do
not operate without supplying operation fluid via the passage 21d,
21g.
[0054] Although the present invention is described above as being
applied to the variable valve timing system equipped with the
camshaft for controlling the opening and the closing of the intake
valve, the present invention can also be applied to variable valve
timing systems quipped with the camshaft for controlling the
opening and closing of the exhaust valve.
[0055] The principles, preferred embodiment and modes of operation
of the present invention have been described in the foregoing
specification. However, the invention which is intended to be
protected is not to be construed as limited to the particular
embodiment disclosed. Further, the embodiment described herein is
to be regarded as illustrative rather than restrictive. Variations
and changes may be made by others, and equivalents employed,
without departing from the spirit of the present invention.
Accordingly, it is expressly intended that all such variations,
changes and equivalents which fall within the spirit and scope of
the present invention as defined in the claims, be embraced
thereby.
* * * * *