U.S. patent number RE38,580 [Application Number 09/707,769] was granted by the patent office on 2004-09-14 for clutch operating mechanism.
This patent grant is currently assigned to Exedy Corporation. Invention is credited to Yasuyuki Hashimoto.
United States Patent |
RE38,580 |
Hashimoto |
September 14, 2004 |
Clutch operating mechanism
Abstract
A clutch cover 25 is disposed opposite to a pressure surface 26a
of a pressure plate 26 and is fixed to a flywheel. The pressure
plate 26 has the pressure surface 26a facing a friction surface 15
of a clutch disk. An annular lever plate 28 is supported at its
outer circumferential edge to a clutch cover 25 and is contacted at
a radially intermediate portion to the pressure plate 26. The
pressure plate 26 is biased to be disengaged from the friction
surface 15 of the clutch disk. A release bearing 31 is in contact
with an inner circumferential edge of the lever plate 28 on the
transmission side. A hydraulic cylinder 32 serves to move the
release bearing 31 in the axial direction.
Inventors: |
Hashimoto; Yasuyuki (Neyagawa,
JP) |
Assignee: |
Exedy Corporation (Osaka,
JP)
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Family
ID: |
32931067 |
Appl.
No.: |
09/707,769 |
Filed: |
November 8, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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639823 |
Apr 29, 1996 |
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Reissue of: |
934517 |
Sep 22, 1997 |
05833041 |
Nov 10, 1998 |
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Foreign Application Priority Data
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May 12, 1995 [JP] |
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7-114951 |
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Current U.S.
Class: |
192/85.51;
192/89.25; 192/99A |
Current CPC
Class: |
F16D
13/50 (20130101); F16D 25/087 (20130101) |
Current International
Class: |
F16D
13/50 (20060101); F16D 13/00 (20060101); F16D
25/08 (20060101); F16D 013/02 (); F16D
025/08 () |
Field of
Search: |
;192/85CA,70.3,89.25,89.24,99A,91A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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19958 |
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Apr 1956 |
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DE |
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30 24 196 |
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Jan 1982 |
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DE |
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30 43 861 |
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Aug 1982 |
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DE |
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35 06 349 |
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Aug 1985 |
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DE |
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34 23 499 |
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Jan 1986 |
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DE |
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0 185 176 |
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Jun 1986 |
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EP |
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1 398 339 |
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Mar 1965 |
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FR |
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2 536 141 |
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May 1984 |
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FR |
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2 546 592 |
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Nov 1984 |
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FR |
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2 554 190 |
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May 1985 |
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FR |
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689432 |
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Mar 1953 |
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GB |
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2 010 422 |
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Jun 1979 |
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GB |
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2 087 026 |
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May 1982 |
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GB |
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4-210127 |
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Jul 1992 |
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JP |
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Primary Examiner: Bonck; Rodney H.
Attorney, Agent or Firm: Shinjyu Global IP Counselors,
LLP
Parent Case Text
The present application is a file wrapper continuation of Ser. No.
08/639,823, filed Apr. 29, 1996, now abandoned.
Claims
What is claimed:
1. A clutch mechanism comprising: a clutch cover; an annular
pressure plate disposed within said clutch cover and attached to
said clutch cover for limited axial movement with respect to said
clutch cover, said annular pressure plate having a pressure surface
engagable with a friction face of a clutch disk; an annular lever
plate having an outer circumferential edge engaging a portion of
said clutch cover, said annular lever plate being in contact with
said annular pressure plate radially inward from said outer
circumferential edge; a plurality of strap plates attached to a
radially outward portion of said clutch cover, said strap plates
further connected to a radially outward portion of said annular
pressure plate, and said strap plates are configured to bias said
annular pressure plate away from the clutch disk; a bearing
assembly disposed adjacent to said annular lever plate and
supported about a transmission input shaft for axial movement along
said input shaft, a portion of said bearing assembly configured to
contact an inner circumferential edge of said lever plate; and
wherein said lever plate is formed with a plurality of first slits
extending radially inwardly from an outer circumferential edge
thereof and a plurality of second slits extending radially
outwardly from an inner circumferential edge thereof in an
alternating manner and said annular lever plate has generally no
biasing effect on said annular pressure plate, and wherein each of
said plurality of second slits of said lever plate is further
formed with engagement holes at a terminus thereof, and said clutch
cover is formed with a plurality of support portions, said support
portions being bent to extend in an axial direction such that said
support portions extend through corresponding ones of said
engagement holes.
2. The clutch mechanism as in claim 1 wherein said annular lever
plate has a length R.sub.5 measured from an inner circumferential
edge to an outer circumferential edge thereof, said first slits
have a radial length R.sub.3 and said second slits have a radial
length R.sub.4 such that the radial lengths R.sub.3 and R.sub.4 are
approximately 80% of the length R.sub.5.
3. The clutch mechanism as in claim 1 further comprising a
hydraulic drive mechanism for effecting movement of said
bearing.
4. The clutch mechanism as in claim 1 further comprising a
pneumatic drive mechanism for effecting movement of said
bearing..Iadd.
5. The clutch mechanism according to claim 1, wherein said support
portions extending axially through said engagement holes are
arranged radially inward of said outer circumferential edge of said
lever plate and radially outward of an intermediate portion of said
lever plate, said intermediate portion contacting said pressure
plate. .Iaddend..Iadd.
6. The clutch mechanism according to claim 5, wherein said annular
lever plate has a central hole. .Iaddend..Iadd.
7. The clutch mechanism according to claim 6, wherein said first
slits arranged in an alternating manner with said second slits
extending radially outward from said inner circumferential edge of
said lever plate. .Iaddend..Iadd.
8. The clutch mechanism according to claim 6, wherein said annular
lever plate has a length R.sub.5 measured from said inner
circumferential edge to said outer circumferential edge and each of
said second slits have a length R.sub.4, length R.sub.4 being
approximately 80% of length R.sub.5. .Iaddend..Iadd.
9. The clutch mechanism according to claim 1, wherein said annular
lever plate has a central hole. .Iaddend..Iadd.
10. A clutch mechanism comprising: a clutch cover, said clutch
cover being formed with a plurality of support portions; an annular
pressure plate disposed within said clutch cover and attached to
said clutch cover for limited axial movement with respect to said
clutch cover, said annular pressure plate having a pressure surface
engageable with a friction face of a clutch disk; an annular lever
plate having an outer circumferential edge engaging a portion of
said clutch cover and being in contact with said annular pressure
plate radially inward from said outer circumferential edge, said
lever plate being formed with a plurality of slits, each of said
plurality of slits of said lever plate being further formed with
engagement holes at a terminus thereof, said support portions being
bent to extend in an axial direction such that said support
portions extend through corresponding ones of said engagement
holes, said annular lever plate having generally no biasing effect
on said annular pressure plate; a plate member attached to said
clutch cover, said plate member further connected to said annular
pressure plate, said plate member being configured to bias said
annular pressure plate away from the clutch disk; a bearing
assembly disposed adjacent said annular lever plate and adapted to
be supported about a transmission input shaft for axial movement
along the input shaft, a portion of said bearing assembly
configured to contact said lever plate; and a controller arranged
to apply selectively a load in an axial direction toward said
annular pressure plate to an inner circumferential edge of said
lever plate such that said lever plate moves said pressure plate
toward the clutch disk when the load is applied and said pressure
plate moves away from the clutch disk when the load is removed,
said pressure plate arranged to move away from the clutch disk by
said plate member. .Iaddend..Iadd.
11. The clutch mechanism according to claim 10, further comprising
a hydraulic drive mechanism arranged to move said bearing assembly.
.Iaddend..Iadd.
12. The clutch mechanism according to claim 10, further comprising
a pneumatic drive mechanism arranged to move said bearing assembly.
.Iaddend..Iadd.
13. A clutch mechanism comprising: a clutch cover; an annular
pressure plate disposed within said clutch cover and attached to
said clutch cover for limited axial movement with respect to said
clutch cover, said annular pressure plate having a pressure surface
engageable with a friction face of a clutch disk; an annular lever
plate having an outer circumferential edge arranged to engage a
portion of said clutch cover and arranged to contact said annular
pressure plate radially inward from said outer circumferential
edge, said lever plate being formed with a plurality of slits, each
of said plurality of slits of said lever plate being further formed
with engagement holes at a terminus thereof, and said clutch cover
being formed with a plurality of support portions, said support
portions arranged to extend in an axial direction such that said
support portions extend through corresponding ones of said
engagement holes, said annular lever plate having generally no
biasing effect on said annular pressure plate; a plate number
arranged to move said pressure plate away from the clutch disk when
a force applied to said pressure plate from said lever plate is
eliminated; and a controller arranged to selectively apply a load
in an axial direction toward said annular pressure plate to an
inner circumferential edge of said lever plate such that said lever
plate moves said pressure plate toward the clutch disk when the
load is applied and said pressure plate moves away from the clutch
disk when the load is removed, said pressure plate arranged to move
away from the clutch disk by said plate member. .Iaddend..Iadd.
14. The clutch mechanism according to claim 13, wherein said
support portions extending axially through said engagement holes
are arranged radially inward of said outer circumferential edge of
said lever plate and radially outward of an intermediate portion of
said lever plate, said intermediate portion contacting said
pressure plate. .Iaddend..Iadd.
15. The clutch mechanism according to claim 14, wherein said
annular lever plate has a central hole and said slits extend
radially outward from an inner circumferential edge of said lever
plate. .Iaddend..Iadd.
16. The clutch mechanism according to claim 15, wherein said
annular lever plate has a length R.sub.5 measured from said inner
circumferential edge to said outer circumferential edge and each of
said slits have a length R.sub.4, length R.sub.4 being
approximately 80% of length R.sub.5. .Iaddend..Iadd.
17. The clutch mechanism according to claim 13, wherein said
annular lever plate has a central hole and said slits extend
radially outward from an inner circumferential edge of said lever
plate. .Iaddend..Iadd.
18. A clutch mechanism comprising: a clutch cover; an annular
pressure plate disposed within said clutch cover and attached to
said clutch cover for limited axial movement with respect to said
clutch cover, said annular pressure plate having a pressure surface
engageable with a friction face of a clutch disk; an annular lever
plate having a central hole, said annular lever plate having an
outer circumferential edge arranged to engage a portion of said
clutch cover and arranged to contact said annular pressure plate
radially inward from said outer circumferential edge, said lever
plate being formed with a plurality of slits, said plurality of
slits extending radially outward from an inner circumferential edge
of said lever plate, each of said plurality of slits of said lever
plate being further formed with engagement holes at a terminus
thereof, and said clutch cover being formed with a plurality of
support portions, said support portions arranged to extend in an
axial direction such that said support portions extend through
corresponding ones of said engagement holes, said support portions
being arranged radially inward of said outer circumferential edge
of said lever plate and radially outward of an intermediate portion
of said lever plate, said intermediate portion contacting said
pressure plate, said annular lever plate having a plurality of
outer slits extending radially inward from said outer
circumferential edge of said lever plate, said outer slits arranged
in an alternating manner with said slits extending radially outward
from said inner circumferential edge of said lever plate, said
annular lever plate having generally no biasing effect on said
annular pressure plate; a plate member arranged to move said
pressure plate away from the clutch disk when a force applied to
said pressure plate from said lever plate is eliminated; and a
controller arranged to selectively apply a load to an inner
circumferential edge of said lever plate such that said lever plate
moves said pressure plate toward the clutch disk when the load is
applied and said pressure plate moves away from the clutch disk
when the load is removed, said pressure plate arranged to move away
from the clutch disk by said plate member. .Iaddend.
Description
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates to a clutch operating mechanism, and
more particularly to a clutch operating mechanism used with a
clutch disk, clutch cover and pressure plate, where the clutch
operating mechanism produces force which urges the pressure plate
into engagement with the clutch disk and a flywheel of an
associated engine.
B. Description of Related Art
A conventional clutch mechanism usually includes a clutch disc, a
clutch cover assembly and an actuating mechanism.
The clutch disc typically includes friction surfaces, a plate
member that is coupled to and supports the friction surfaces and a
spline hub elastically coupled to the plate member. Usually, the
elastic coupling between the spline hub and the plate member
includes a spring for dampening unwanted vibrations produced during
the transmission of torque. An input shaft that extends from a
transmission usually extends through the spline hub.
The clutch cover assembly usually includes a clutch cover connected
to the flywheel of the engine, an annular pressure plate disposed
within the clutch cover, and a diaphragm spring. The clutch cover
and pressure plate confine and engage the clutch disk between the
pressure plate and a flywheel.
The release mechanism is provided with a release bearing which
engages an inner circumferential edge of the diaphragm spring. A
drive mechanism connected to the release mechanism provides control
for moving the release bearing in axial directions to move the
diaphragm spring. In the case where the drive mechanism includes,
for example, a hydraulic cylinder, the hydraulic cylinder is
connected to a master cylinder. When a driver or operator
manipulates a switch or lever, hydraulic fluid is forced from the
master cylinder to the hydraulic cylinder. As a result, a piston
within the hydraulic cylinder is moved in a predetermined axial
direction so that the release bearing is also moved in the axial
direction. The release bearing causes the inner circumferential
edge of the diaphragm spring to move, so that the biasing force
from the diaphragm spring to the pressure plate is released. As a
result, the clutch is disengaged.
In the above-described clutch device, the movement of the piston
works against the force or pressure from the diaphragm spring. As
the diaphragm spring is moved, it is necessary to simultaneously
control the load from the piston imparted to the release bearing
that works against the force of the spring and control the distance
the diaphragm spring moves. The distance the diaphragm spring is
often referred to as the displacement of the diaphragm spring or
stroke of the diaphragm spring. Since both force and stroke must be
controlled, the structure of the control section is complicated,
otherwise the reliability of the clutch control may be compromised.
Also, since the spring characteristics of the diaphragm spring
affect the pressure load, the reliability of the clutch control may
be further compromised.
SUMMARY OF THE INVENTION
An object of the present invention is to enhance the reliability of
a clutch control in a clutch device.
In accordance with a first aspect of the present invention, a
clutch mechanism includes a clutch cover and an annular pressure
plate disposed within the clutch cover and attached to a radially
outward portion thereof for limited axial movement with respect to
the clutch cover, the annular pressure plate having a pressure
surface engageable with a friction face of a clutch disk. An
annular lever plate is supported at an outer circumferential edge
of the clutch cover, the annular lever plate being in contact with
the annular pressure plate radially inward from the outer
circumferential edge of the clutch cover. The annular pressure
plate is biased away from engagement with the clutch disk.
Preferably, the clutch cover includes a plurality of strap plates
attached to a radially outward portion thereof, the strap plates
further connected to a radially outward portion of the annular
pressure plate.
Preferably, the strap plates are configured to bias the annular
pressure plate away from the clutch disk.
Preferably, the strap plates and the annular lever plate are both
configured to bias the annular pressure plate away from the clutch
disk.
Preferably, a bearing assembly is disposed adjacent to the annular
pressure plate and supported about a transmission input shaft for
axial movement along the input shaft, a portion of the bearing
assembly configured to contact an inner circumferential edge of the
lever plate. A hydraulic drive mechanism is connected to the
bearing for effecting movement of the bearing.
Preferably, the lever plate is formed with a plurality of first
slits extending radially inwardly from an outer circumferential
edge thereof and a plurality of second slits extending radially
outwardly from an inner circumferential edge thereof in an
alternating manner.
Alternatively, a pneumatic drive mechanism may be employed for
effecting movement of the bearing.
In accordance with another aspect of the present invention, the
clutch mechanism includes a clutch cover having a plurality of
strap plates attached to a radially outward portion thereof and an
annular pressure plate disposed within the clutch cover and
attached to the strap plate for limited axial movement with respect
to the clutch cover, the annular pressure plate having a pressure
surface engageable with a friction face of a clutch disk. An
annular lever plate is supported at an outer circumferential edge
of the clutch cover, the annular lever plate being in contact with
the annular pressure plate radially inward from the outer
circumferential edge of the clutch cover. The annular pressure
plate is biased away from engagement with the clutch disk by the
strap plates.
Preferably, the strap plates are configured to bias the annular
pressure plate away from the clutch disk and the annular lever
plate is formed with a plurality of first slits extending radially
inwardly from an outer circumferential edge thereof and a plurality
of second slits extending radially outwardly from an inner
circumferential edge thereof in an alternating manner such that
biasing effects of the annular lever plate are less than the strap
plates.
Preferably, the strap plates and the annular lever plate are
configured to bias the annular pressure plate away from the clutch
disk.
In another aspect of the invention, a clutch mechanism includes a
clutch cover having a plurality of strap plates attached to a
radially outward portion thereof and an annular pressure plate
disposed within the clutch cover and attached to the strap plate
for limited axial movement with respect to the clutch cover, the
annular pressure plate having a pressure surface engageable with a
friction face of a clutch disk. An annular lever plate is supported
at an outer circumferential edge of the clutch cover, the annular
lever plate being in contact with the annular pressure plate
radially inward from the outer circumferential edge of the clutch
cover. The annular pressure plate is biased away from engagement
with the clutch disk by the strap plates and the annular lever
plate.
Preferably, the annular lever plate is formed with a plurality of
first slits extending radially inwardly from an outer
circumferential edge thereof and a plurality of second slits
extending radially outwardly from an inner circumferential edge
thereof in an alternating manner.
Preferably, the annular lever plate has a length R.sub.5 measured
from an inner circumferential edge to an outer circumferential edge
thereof, the first slits have a radial length R.sub.3 and the
second slits have a radial length R.sub.4 such that the radial
lengths R.sub.3 and R.sub.4 are approximately 80% of the length
R.sub.5.
In the clutch mechanism according to the one aspect of the
invention, when the bearing is moved toward the flywheel by the
drive mechanism, the annular lever plate is deformed along the
outer circumferential edge thereof as a fulcrum so that a radially
intermediate portion thereof presses the pressure plate toward the
flywheel. As a result, the pressure surface of the pressure plate
causes the friction surface of the clutch disc to frictionally
engage with the flywheel. In this case, a load which is several
times larger than a load from the bearing to the inner
circumferential edge of the diaphragm spring is applied to the
pressure plate, corresponding to a ratio (lever ratio) of a length
from the inner circumferential edge of the lever plate to the outer
circumferential edge thereof to a length from the outer
circumferential edge to the radially intermediate portion.
When the bearing returns to a position toward the transmission by
release of fluid pressure by the drive mechanism, the force
transmitted by the annular lever plate to the pressure plate is
overcome by the force of the strap plates and thus, the clutch is
disengaged.
In this clutch mechanism, a conventional diaphragm spring is not
used for biasing the pressure plate. The pressure transmitted from
the lever plate to the pressure plate is provided only by movement
of the bearing against the inner circumferential edge of the
annular lever plate. Thus, it is possible to control the clutch
mechanism only by controlling the position of the bearing. The
forces normally associated with a diaphragm spring are eliminated
thus reducing the force required to operate the clutch mechanism.
Further, the lever action of the annular lever mechanism multiplies
the force from the bearing against the pressure plate, thus further
reducing the force necessary to control engagement and
disengagement of the clutch mechanism. Therefore, the reliability
of the clutch control is enhanced.
In the clutch mechanism according to the present invention, since
the first slits and second slits are formed in the lever plate, the
lever plate has only the minimal rigidity.
These and other objects, features, aspects and advantages of the
present invention will become more fully apparent from the
following detailed description of the present invention when taken
in conjunction with the accompanying drawings where like reference
numerals denote corresponding parts throughout, in which:
BRIEF DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic side cross-section view showing a clutch
assembly having a clutch disk and a clutch disk actuation
mechanism, in accordance with one embodiment of the present
invention, with the clutch disk shown in a dis-engaged
position;
FIG. 2 is a schematic side cross-section view similar to FIG. 1,
showing the clutch disk in an engaged position; and
FIG. 3 is a plan view of a lever plate shown removed from the
clutch assembly depicted in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be described with reference to the
accompanying drawings.
A clutch assembly mechanism 1 is shown in FIG. 1 according to one
embodiment of the present invention. In this clutch assembly
mechanism 1, the line O--O denotes a rotary axis of the clutch
assembly mechanism 1. The clutch assembly mechanism 1 serves to
selectively transmit torque from a flywheel 2 to an input shaft 3
of a transmission (not shown, but disposed on the right side in
FIG. 1). The clutch assembly mechanism 1 is mainly composed of a
clutch disc assembly 6, a clutch cover assembly 7 and a hydraulic
release device 8. The outer circumference of the clutch assembly
mechanism 1 is covered by a housing 11. Also, a transmission
housing 12 is disposed on the housing 11.
The disc assembly 6 is provided with friction surfaces 15 which are
connected the radially outer circumferential sides of a clutch
plate 16 and a retaining plate 17. The disc assembly 6 also
includes a hub 14 having a flange 18 formed therewith, the flange
18 extending between the plates 16 and 17. A plurality of coil
springs 20 elastically couple the flange 18 of the hub 14 with the
plates 16 and 17 in a circumferential direction. A friction
generating mechanism 21 is disposed between the plate 16 and the
hub 14 for producing friction resistance in response to relative
rotation between the hub 14 and the plates 16 and 17. The friction
surfaces 15 are disposed adjacent to a frictional surface on the
flywheel 2. The inner circumferential portion of the hub 14 is
formed with spline gear teeth (not shown) which engage the main
drive shaft 3.
The clutch cover assembly 7 is mainly composed of a clutch cover
25, a pressure plate 26, a plurality of strap plate 27 (although
only one strap plate 27 is shown) and a lever plate 28. The clutch
cover 25 is dish-shaped with a large hole in the central portion.
The outer circumferential edge of the clutch cover 25 is fixed to
the flywheel 2 by bolts (not shown). The pressure plate 26 is
disposed within the clutch cover 25. As a result, a surface of the
pressure plate 26 on the outer circumferential side is covered by
the clutch cover 25. The pressure plate 26 has a pressure surface
26a facing the friction surfaces 15 of the clutch disc assembly 6.
An annular projection 26b is formed on the inner circumferential
side of the pressure plate 26 and extends toward the
transmission.
The strap plates 27 couple the pressure plate 26 and the clutch
cover 25 with each other at three spaced apart positions so that
the pressure plate 26 and the clutch cover 25 are confined for
rotation with each other. Further, the strap plates 27 bias the
pressure plate 26 to pull away from the flywheel 2 such that in an
unstressed state (where no force is applied by the hydraulic
release device 8), the pressure plate 26 is maintained generally in
the position shown in FIG. 1.
The lever plate 28 is made of an annular planar member having a
central hole 28a as best shown in FIG. 3. The central hole 28a has
a radius R.sub.1. The lever plate 28 has an overall radius of
R.sub.2. A plurality of first slits 28b extending radially inwardly
from the outer circumferential edge are formed in the lever plate
28 and have a radial length R.sub.3. Furthermore, a plurality of
second slits 28c are formed in the lever plate 28 and extend
radially outwardly from the inner circumferential edge of the
central hole 28a. The second slits 28c have a radial length
R.sub.4. The first slits 28b and the second slits 28c are
alternately formed in an alternative manner in the circumferential
direction in the lever plate 28. Due to the slits 28b and 28c, the
lever plate 28 has a generally low level of rigidity. Further, the
lever plate 28 has little biasing effect on the pressure plate
26.
Also, engagement holes 28d are formed at the outermost ends of the
second slits 28c. Support portions 25a of the clutch cover 25
extend into the engagement holes 28d. With such an arrangement, the
lever plate 28 rotates together with the clutch cover 25 as
one-piece. The surface of the lever plate 28, on the transmission
side, at the outer circumferential edge are in contact with the
clutch cover 25. Furthermore, an intermediate portion of the lever
plate 28 radially inward from the engagement holes 28d is in
contact with the projection 26b of the pressure plate 26.
The hydraulic release device 8 is mainly composed of a release
bearing 31 and a hydraulic cylinder 32. In the release bearing 31,
a contact member 31a that engages an inner race thereof is in
contact with the inner circumferential edge of the lever plate
28.
The hydraulic cylinder 32 is mainly composed of an annular housing
35, an annular piston 36, an annular carrier 37 and a hydraulic
pressure supplying pipe 38. The annular housing 35 is fixed to the
transmission housing 12 and is disposed coaxially with the rotary
axis O--O of the clutch assembly mechanism 1. An annular oil
chamber 35a extending axially about the input shaft 3 is formed in
the annular housing 35. One end face of the oil chamber 35a is open
toward the flywheel 2.
The annular piston 36 is disposed within the oil chamber 35a
extending into the open end face of the oil chamber 35a. The
annular carrier 37 is fixed to the distal end of the annular piston
36 and covers the outer circumferential portion of the release
bearing 31. The annular carrier 37 is also connected to the outer
race of the release bearing near to the transmission housing
12.
The hydraulic pressure supplying pipe 38 and an air bleeder pipe
(not shown) are fixed to the annular housing 35 and are in
communication with the oil chamber 35a. The hydraulic pressure
supplying pipe 38 is connected to a hydraulic controller 50 having
a master cylinder (not shown) and an actuation mechanism (not
shown) for manipulating fluid pressure within the oil chamber
35a.
The operation of the invention will now be explained.
Clutch Engagement (FIG. 1 to FIG. 2)
When a driver or an operator wishes to engage the clutch assembly
mechanism 1, the operator manipulates, for example, a switch or the
lever associated to the hydraulic controller 50, to a clutch
engagement position. In response, the hydraulic drive device 50
causes a predetermined pressure of hydraulic fluid to be fed from
the hydraulic drive device 50 through the hydraulic pressure
supplying pipe 38 to the oil chamber 35a of the hydraulic cylinder
32. As a result, the annular piston 36 is moved toward the flywheel
2, and simultaneously therewith, the release bearing 31 is moved
from the position shown in FIG. 1 to the position shown in FIG. 2.
In this case, the release bearing 31 imparts a load or force to the
inner circumferential edge of the annular lever plate 28 such that
the position of the lever plate 28 is changed. Because of lever
action, a load from the movement of the release bearing 31 is
multiplied several times by the lever plate 28 and the multiplied
load is applied to the pressure plate 26. The pressure surface 26a
of the pressure plate 26 causes the friction surface 15 to be
engaged with the flywheel 2. As a result, the torque from the
flywheel is transmitted to the clutch disc assembly 6 and is output
to the main drive shaft 3.
Incomplete Clutch Engagement
When a driver or an operator wishes to partially engage the clutch
assembly mechanism 1, the operator manipulates, for example, the
switch or the lever associated to the hydraulic controller 50, to
an incomplete clutch engagement position. In response, the
hydraulic drive device 50 causes a predetermined pressure of
hydraulic fluid to be fed from the hydraulic drive device 50
through the hydraulic pressure supplying pipe 38 to the oil chamber
35a of the hydraulic cylinder 32. In the hydraulic cylinder 32, a
hydraulic pressure by which the annular piston 36 is pressed on the
engine side may be reduced within the oil chamber 35a. As a result,
the load given from the release bearing 31 to the lever plate 28 is
reduced from the load in the above-described clutch engagement
state, so that the pressure load to the pressure plate 26 is
reduced. Thus, the clutch is kept in the incomplete clutch
engagement and may slip.
Clutch Disengagement (FIG. 2 to FIG. 1)
When a driver or an operator wishes to dis-engage the clutch
assembly mechanism 1, the operator manipulates, a switch or the
lever associated to the hydraulic controller 50, to a clutch
dis-engagement position. In response, the hydraulic drive device 50
causes hydraulic fluid to be drained from the hydraulic drive
device 50 through the hydraulic pressure supplying pipe 38 from the
oil chamber 35a of the hydraulic cylinder 32. As a result, the load
given from the lever plate 28 to the pressure plate 26 is
eliminated. In this case, the pressure plate 26 is moved toward the
transmission by the biasing force from the strap plates 27.
Consequently, the friction surfaces 15 of the clutch disc assembly
6 separate away from the flywheel 2 and the pressure plate 26 to
dis-engage the clutch.
In the above-described clutch operation, a conventional diaphragm
spring is not used for imparting the pressure load to the pressure
plate 26. Namely, the pressure transmitted to the pressure plate 26
urging it toward the flywheel 2 comes from the movement of the
release bearing 31, not from any biasing from the lever plate 28.
Movement of the release bearing 31 is controlled by the fluid
pressure within the chamber 35a. Thus, to control the clutch
pressure load, since it is sufficient to control the load only from
the release bearing 31 to the lever plate 28, the reliability of
the clutch control is enhanced.
Also, since the first slits 28b and the second slits 28c are formed
in the lever plate 28, the lever plate 28 has minimal rigidity as a
lever. As a result, the reliability of the clutch control is
improved.
It should be appreciated that the lever plate 28 and the slits 28b
and 28c may formed therein may be dimensioned to provide the lever
plate 28 with sufficient biasing force to assist the strap plates
27 in biasing the pressure plate 26 away from the friction surface
15. Alternatively, the lever plate 28 and the slits 28b and 28c may
be configured to provide little or no biasing force whatsoever.
Further, the lever plate 28 and the slits 28b and 28c may be
configured to slightly counteract the biasing force of the strap
plates 27 so that the pressure plate 26 biased away from the
friction surface 15 by a minimal amount of force thus reducing the
load necessary from the hydraulic controller 100 to engage the
pressure plate 26 with the friction surface 15. Determination of
the biasing effects of the strap plates 27 and the lever plate 28
are determined by application of the clutch assembly 1 and the
usage thereof. Changes in the biasing effects of the lever plate 28
may be made by, for instance, changing the dimensions of the radii
R.sub.3 and R.sub.4. In the embodiment shown in FIG. 3, the radii
R.sub.3 and R.sub.4 are about 80% of the length R.sub.5 of the
lever plate 28. However, regardless of the biasing effects of the
strap plate 27 and the lever plate 28, the pressure plate 26 is
biased away from engagement with the friction surface 15.
As another embodiment, it is possible to use a pneumatic drive
device instead of the hydraulic drive device 50. The other
structure is the same as that described above.
Since the first slits and the second slits are formed in the lever
plate, the lever plate has minimal rigidity, which reduces possible
affects to the pressure load.
Various details of the invention may be changed without departing
from its spirit nor its scope. Furthermore, the foregoing
description of the embodiments according to the present invention
is provided for the purpose of illustration only, and not for the
purpose of limiting the invention as defined by the appended claims
and their equivalents.
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