Title: Friction clutch with intermediate plate mounting system
Abstract: A friction clutch is provided that includes a clutch cover, an intermediate plate that is spaced apart from an engine flywheel, a first friction disk positioned between the flywheel and the intermediate plate, a pressure plate spaced apart from the intermediate plate and a second friction disk positioned between the intermediate plate and the pressure plate. The clutch further includes a first drive strap for applying a load to the intermediate plate, a second drive strap for applying a load to the pressure plate and a separator arm attached to the intermediate plate. The separator arm engages the second drive strap such that axial movement of the intermediate plate relative to the clutch cover is a fraction of the corresponding axial movement of the pressure plate during engagement and disengagement of the clutch.
Patent Number: 6,866,132 Issued on 03/15/2005 to Gochenour, et al.
| Inventors:
|
Gochenour; Daniel V. (Auburn, IN);
Peterson; Steven M. (Fort Wayne, IN);
Schlosser; Kevin (Auburn, IN)
|
| Assignee:
|
Eaton Corporation (Cleveland, OH)
|
| Appl. No.:
|
107514 |
| Filed:
|
March 27, 2002 |
| Current U.S. Class: |
192/70.18; 192/70.28 |
| Intern'l Class: |
F16D 013//56 |
| Field of Search: |
192/70.25,70.18,70.28
|
References Cited [Referenced By]
U.S. Patent Documents
| 4257502 | Mar., 1981 | Riese | 192/70.
|
| 4431097 | Feb., 1984 | Scheer | 192/70.
|
| 4437555 | Mar., 1984 | Tomm et al. | 192/70.
|
| 4751990 | Jun., 1988 | Schraut et al.
| |
| 4848555 | Jul., 1989 | Riese et al. | 192/70.
|
| 4958714 | Sep., 1990 | Cooke et al. | 192/70.
|
| 5090537 | Feb., 1992 | Fukuda | 192/70.
|
| 5170873 | Dec., 1992 | Fukuda | 192/70.
|
| 5226515 | Jul., 1993 | Hartshorn | 192/70.
|
| 6039161 | Mar., 2000 | Tanaka et al. | 192/70.
|
| Foreign Patent Documents |
| 3041342 | Jun., 1982 | DE.
| |
| 2 629 881 | Oct., 1989 | FR.
| |
Other References
Derwent English Abstract for FR 2 629 881 A1.
International Search Report, 3 pages.
|
Primary Examiner: Lorence; Richard M.
Attorney, Agent or Firm: Rader, Fishman & Grauer PLLC
Claims
What is claimed is:
1. A friction clutch comprising:
a flywheel rotatable about an axis of rotation;
a clutch cover fixed to the flywheel for rotation therewith;
an intermediate plate spaced apart from the flywheel and disposed within
the cover;
a first friction disk positioned between the flywheel and intermediate
plate;
a pressure plate disposed within the cover between the intermediate plate
and the cover and spaced apart from the intermediate plate;
a second friction disk positioned between the intermediate plate and the
pressure plate;
a first drive strap disposed between the intermediate plate and the cover,
the first drive strap rotatively fixing the intermediate plate to the
cover and biasing the intermediate plate away from the flywheel;
a second drive strap disposed between the pressure plate and the cover, the
second drive strap rotatively fixing the pressure plate to the cover and
biasing the pressure plate away from the flywheel; and
at least one fastener that removably connects the first drive strap to the
cover, the intermediate plate configured to slide axially on a portion of
the fastener that extends beyond the cover.
2. The clutch according to claim 1, further including a sleeve disposed
between the fastener and the intermediate plate.
3. The clutch according to claim 2, wherein the intermediate plate includes
a lug portion having an aperture therethrough that is sized to slidingly
receive the sleeve.
4. The clutch according to claim 1, wherein the fastener is configured to
limit axial movement of the intermediate plate.
5. A friction clutch comprising:
a flywheel rotatable about an axis of rotation;
a clutch cover fixed to the flywheel for rotation therewith;
an intermediate plate spaced apart from the flywheel and disposed within
the cover;
a first friction disk positioned between the flywheel and intermediate
plate;
a pressure plate disposed within the cover between the intermediate plate
and the cover and spaced apart from the intermediate plate;
a second friction disk positioned between the intermediate plate and the
pressure plate;
a first drive strap disposed between the intermediate plate and the cover,
the first drive strap rotatively fixing the intermediate plate to the
cover and biasing the intermediate plate away from the flywheel;
a second drive strap disposed between the pressure plate and the cover, the
second drive strap rotatively fixing the pressure plate to the cover and
biasing the pressure plate away from the flywheel;
a fastener that removably connects the first drive strap to the cover, the
intermediate plate configured to slide axially on a portion of the
fastener that extends beyond the cover; and
a separator arm attached to the intermediate plate, the separator arm
engaging the second drive strap such that axial movement of the
intermediate plate relative to the clutch cover is a fraction of the
corresponding axial movement of the pressure plate during engagement and
disengagement of the clutch.
6. The clutch according to claim 5, wherein the separator arm includes a
head portion that engages the second drive strap and a base portion
connected to the intermediate plate.
7. The clutch according to claim 6, wherein the head portion is secured to
the base portion by a press fit connection.
8. The clutch according to claim 6, wherein the head portion is secured to
the base portion by a snap-together connection.
9. The clutch according to claim 5, further including a sleeve disposed
between the fastener and the intermediate plate.
10. The clutch according to claim 9, wherein the intermediate plate
includes a lug portion having an aperture therethrough that is sized to
slidingly receive the sleeve.
11. The clutch according to claim 5, wherein the fastener is configured to
limit axial movement of the intermediate plate.
12. A friction clutch comprising:
a flywheel rotatable about an axis of rotation;
a clutch cover fixed to the flywheel for rotation therewith;
an intermediate plate spaced apart from the flywheel and disposed within
the cover;
a first friction disk positioned between the flywheel and intermediate
plate;
a pressure plate disposed within the cover between the intermediate plate
and the cover and spaced apart from the intermediate plate;
a second friction disk positioned between the intermediate plate and the
pressure plate;
a first drive strap disposed between the intermediate plate and the cover
and the first drive strap rotatively fixing the intermediate plate to the
cover and biasing the intermediate plate away from the flywheel;
a second drive strap disposed between the pressure plate and the cover and
the second drive strap rotatively fixing the pressure plate to the cover
and biasing the pressure plate away from the flywheel; and
a separator arm having
a base portion fixed to the intermediate plate, and
a separate friction reducing head portion secured to the base portion and
engaging the second drive strap so as to follow deflection of the second
drive strap at a location of engagement therebetween such that axial
travel of the intermediate plate relative the clutch cover associated with
moving between a clutch engaged condition and a clutch disengaged
condition is a fraction of the corresponding axial movement of the
pressure plate during engagement and disengagement of the clutch.
13. The friction clutch according to claim 12, wherein the head portion is
circumferentially and axially offset from the base portion and
cantilevered over the first drive strap, thereby permitting deflection of
the first drive strap toward the head portion in the engaged condition.
14. The friction clutch according to claim 12, wherein the head portion
engages the second drive strap directly.
15. The friction clutch according to claim 12, wherein a friction reducing
member is disposed between the head portion and the second drive strap.
16. The clutch according to claim 12, wherein the head portion includes a
substantially flat land where the separator arm contacts the second drive
strap.
17. The clutch according to claim 12, wherein the base portion includes an
aperture therethrough that receives a fastener to connect the separator
arm and the first drive strap to the intermediate plate.
18. The clutch according to claim 12, wherein at least one of the head
portion and the base portion includes a connector adapter to secure the
head portion to the base portion.
19. The clutch according to claim 18, wherein the connector is a press fit
style connection.
20. The clutch according to claim 18, wherein the connector is a
snap-together connection.
21. The clutch according to claim 12, wherein the head portion is made from
a friction reducing material.
22. The clutch according to claim 21, wherein the friction reducing
material is PTFE.
23. A friction clutch comprising:
a flywheel rotatable about an axis of rotation;
a clutch cover fixed to the flywheel for rotation therewith;
an intermediate plate spaced apart from the flywheel and disposed within
the cover;
a first friction disk positioned between the flywheel and intermediate
plate;
a pressure plate disposed within the cover between the intermediate plate
and the cover and spaced apart from the intermediate plate;
a second friction disk positioned between the intermediate plate and the
pressure plate;
a first drive strap disposed between the intermediate plate and the cover,
the first drive strap rotatively fixing the intermediate plate to the
cover and biasing the intermediate plate away from the flywheel;
a second drive strap disposed between the pressure plate and the cover and
the second drive strap rotatively fixing the pressure plate to the cover
and biasing the pressure plate away from the flywheel; and
a separator arm having
a base portion fixed to the intermediate plate, and
a head portion engaging the second drive strap so as to follow deflection
of the second drive strap at a location of engagement therebetween such
that axial travel of the intermediate plate relative the clutch cover
associated with moving between a clutch engaged condition and a clutch
disengaged condition is a fraction of the corresponding axial movement of
the pressure plate during engagement and disengagement of the clutch, the
head portion including a first generally curved portion and a second
generally flat portion where the separator arm contacts the second drive
strap.
24. The clutch according to claim 23, wherein the separator arm includes at
least one shoulder to inhibit rotation of the separator arm relative to
the intermediate plate.
25. A friction clutch comprising:
a flywheel rotatable about an axis of rotation;
a clutch cover fixed to the flywheel for rotation therewith;
an intermediate plate spaced apart from the flywheel and disposed within
the cover;
a first friction disk positioned between the flywheel and intermediate
plate;
a pressure plate disposed within the cover between the intermediate plate
and the cover and spaced apart from the intermediate plate;
a second friction disk positioned between the intermediate plate and the
pressure plate;
a first drive strap disposed between the intermediate plate and the cover,
the first drive strap rotatively fixing the intermediate plate to the
cover and biasing the intermediate plate away from the flywheel;
a second drive strap disposed between the pressure plate and the cover, the
second drive strap rotatively fixing the pressure plate to the cover and
biasing the pressure plate away from the flywheel;
a separator arm fixed to the intermediate plate;
a friction reducing member slidingly attached to the second drive strap and
disposed between the separator arm and the second drive strap, the
separator arm engaging the friction reducing member so as to follow
deflection of the second drive strap at a location of engagement
therebetween such that axial travel of the intermediate plate relative the
clutch cover associated with moving between a clutch engaged condition and
a clutch disengaged condition is a fraction of the corresponding axial
movement of the pressure plate during engagement and disengagement of the
clutch.
26. The clutch according to claim 25, wherein the friction reducing member
is made from a friction reducing material.
27. The clutch according to claim 26, wherein the friction reducing
material is PTFE.
28. The clutch according to claim 25, wherein the friction reducing member
includes a contoured engagement surface and a duct therethrough for
receiving the second drive strap.
29. The clutch according to claim 25, wherein the friction reducing member
includes a contoured engagement surface and at least one bendable clamp.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a multi-disk friction clutch.
More particularly, the present invention relates to a multi-disk friction
clutch having means for promoting uniform engagement and wear of the
friction disks.
2. Description of the Related Art
Friction clutches for use in transmitting rotational torque between a motor
vehicle engine and a transmission are well known in the art. One known
friction clutch design includes two friction disks, a pressure plate, an
intermediate plate, and a clutch cover mounted for rotation about a common
axis. The clutch disks, pressure plate and intermediate plate are axially
moveable relative to each other so that the pressure plate may be moved
relative to the cover to press the two friction disks and the interposed
intermediate plate axially against an engine flywheel. A series of drive
straps, each generally including one or more resilient elements that are
layered to form a leaf spring, are placed around the peripheries of the
intermediate plate and pressure plate to provide a biasing force against
the plates. During engagement of the clutch, the intermediate plate,
pressure plate and friction disks are pressed against the engine flywheel,
such that rotation of the flywheel causes rotation of the friction disks.
During disengagement of the clutch, the drive straps bias the intermediate
plate and pressure plate in a direction away from the flywheel to separate
the intermediate plate and pressure plate from the friction disks.
A basic problem with conventional friction clutches is that the
intermediate plate is uncontrolled during engagement and disengagement of
the clutch. In other words, it is generally difficult to achieve
simultaneous engagement of the intermediate plate and the pressure plate
with the friction disks and simultaneous disengagement of the friction
disks from the interposed intermediate plate. If the friction disks are
engaged sequentially rather than simultaneously, the friction material on
one friction disk may be consumed more rapidly than the friction material
on the other friction disk, thereby reducing the useful life of the
clutch.
To ensure virtually simultaneous engagement of the friction disks, several
designs have been proposed that force the travel of the intermediate plate
to closely coincide with pressure plate travel. One known design
incorporates a mechanism that includes a separator element bolted to the
radially outer side of the intermediate plate and a lever attached to the
mid-point of the drive straps that bias the pressure plate. Engagement of
the separator element with the lever limits axial movement of the
intermediate plate to approximately half of the axial movement of the
pressure plate during engagement and disengagement of the clutch.
Accordingly, the friction disks are engaged by the intermediate plate and
pressure plate nearly simultaneous, providing substantially uniform wear
of the friction disks and a smooth engagement of the clutch.
One limitation of the aforementioned design is that it requires a hole
and/or slot to be machined into the radially outer surface of the
intermediate plate to connect the mechanism. Another limitation is that
the mechanism must be affixed to the intermediate plate using a separate
fastener(s), which, together with the machined holes and/or slot in the
intermediate plate, add to the complexity and cost of manufacturing the
prior art clutch assembly. Still another limitation is that the separator
element must directly engage the lever to protect the drive straps from
direct and damaging engagement by the separator element, and to provide a
more precise control of the displacement of the pressure plate relative to
the intermediate plate. Yet another limitation is that maximum axial
movement of the intermediate plate is generally uncontrolled, permitting
the connected drive straps to be overextended and damaged.
Accordingly, there exists a need for a simplified device that can be easily
and cost effectively affixed to a clutch to achieve the desired control of
intermediate plate travel relative to the pressure plate.
SUMMARY OF THE INVENTION
In a preferred embodiment of the present invention a friction clutch is
provided that includes a clutch cover, an intermediate plate that is
spaced apart from an engine flywheel, a first friction disk positioned
between the flywheel and the intermediate plate, a pressure plate spaced
apart from the intermediate plate and a second friction disk positioned
between the intermediate plate and the pressure plate. The clutch further
includes at least one first drive strap for applying a load to the
intermediate plate, at least one second drive strap for applying a load to
the pressure plate and at least one separator arm attached to the
intermediate plate. The separator arm engages the second drive strap such
that axial movement of the intermediate plate relative to the clutch cover
is a fraction of the corresponding axial movement of the pressure plate
during engagement and disengagement of the clutch.
In another embodiment of the present invention, at least one fastener is
provided for removably connecting the first drive strap to the cover. The
intermediate plate is configured to slide axially on a portion of the
fastener that extends beyond the cover. The axial movement of the
intermediate plate is limited by the fastener to prevent permanent
deformation of or otherwise damage the first drive strap.
Among other advantages, the separator arm of the present invention can be
attached to the intermediate plate using existing fasteners, i.e., the
fasteners used to secure the first drive straps to the intermediate plate,
thereby eliminating one or more manufacturing steps. Another advantage is
that the separator arm material can be readily tailored to the
requirements of a particular clutch assembly to reduce friction between
the separator arm and the engaged second drive strap. Unlike the prior
art, the separator arm can directly engage the second drive strap, without
the use of a lever. Still another advantage is that the intermediate plate
can be easily removed from the clutch to facilitate repair or replacement
of the friction disks. Yet another advantage is that axial movement of the
intermediate plate is precisely controlled to prevent damage to the first
drive straps during operation of the clutch.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic representation of a double-disk friction clutch
according to a preferred embodiment of the present invention;
FIG. 2 is a partial sectional view of the clutch of FIG. 1;
FIG. 3A is a side view of a separator arm shown in FIG. 2 according to a
preferred embodiment of the present invention;
FIG. 3B is a front cross-sectional view of the separator arm of FIG. 3A;
FIG. 4 is a partial cross-sectional view of the clutch of FIGS. 1 and 2
showing a separator arm according to an alternate embodiment of the
present invention;
FIGS. 5A and 5B are front views of the separator arm of FIG. 4 illustrating
the preferred methods of connecting a head portion of the separator arm to
a base portion;
FIG. 6 is a partial cross-sectional view of the clutch of FIGS. 1 and 2
showing a separator arm according to another alternate embodiment of the
present invention;
FIG. 7 is a partial cross-sectional view of the clutch of FIG. 6 showing
the separator arm and a friction reducing member;
FIG. 8 is a cross-sectional view of the friction reducing member of FIG. 7;
FIG. 9 is a partial cross-sectional view of the clutch of FIG. 7 showing an
alternate embodiment of the friction reducing member; and
FIG. 10 is a cross-sectional view of the friction reducing member of FIG.
9.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, the preferred embodiments of the present
invention are shown in detail. Referring to FIG. 1, a diagrammatic
representation of a double-disk friction clutch 20 is illustrated, while a
partial sectional view of clutch 20 is illustrated in FIG. 2. Clutch 20
includes a cover 22 that is detachably secured to a flywheel 24 of an
internal combustion engine (not illustrated). Within cover 22 is disposed
a first friction disk 26 adjacent flywheel 24 and an intermediate plate 28
adjacent first friction disk 26. A second friction disk 30 is disposed
adjacent a transmission-facing side 32 of intermediate plate 28 and a
pressure plate 34 is disposed adjacent a transmission-facing side 36 of
second friction disk 30. First and second friction disks 26, 30 are
secured for rotation on a transmission input shaft 38, but are axially
moveable in relation thereto.
Intermediate plate 28 and pressure plate 34 are secured for rotation with
cover 22 and, like friction disks 26 and 30, are axially moveable in
relation thereto. In the illustrated embodiment, pressure plate 34 abuts a
diaphragm spring 40 that moveably connects pressure plate 34 to a release
mechanism 42. Release mechanism 42 is selectively controlled by a vehicle
operator to engage and disengage clutch 20. However, it will be
appreciated that the present invention can be used with a variety of
clamp-load generating release mechanisms besides a diaphragm spring. One
example well known in the art is the use of a plurality of levers and
compression springs. Another alternative is a centrifugally actuated
clutch having both an intermediate plate and a pressure plate. In the
centrifugally actuated clutch, the clamping load is generated by pivoted
weights, which swing radially outwardly with rotation of the clutch
assembly.
Referring now to FIGS. 1 and 2, intermediate plate 28 and pressure plate 34
are moveably connected to cover 22 by first and second drive straps 44 and
46, respectively. Drive straps 44, 46 preferably include a plurality of
resilient elements that are layered together to form a leaf spring, as is
known in the art. First drive strap 44 provides a force on intermediate
plate 28 for biasing intermediate plate 28 in a direction toward pressure
plate 34. Similarly, second drive strap 46 provides a force against
pressure plate 34 to ensure that pressure plate 34 is in continuous
contact with diaphragm spring 40. In return, diaphragm spring 40 applies a
clamping force against pressure plate 34 when engagement of clutch 20 is
desired. While FIGS. 1 and 2 show only one drive strap 44, 46 for each of
intermediate plate 28 and pressure plate 34, respectively, a plurality of
drive straps 44 and 46 are preferably distributed about the peripheries of
intermediate plate 28 and pressure plate 34.
Referring exclusively to FIG. 2, a first end 48 of second drive strap 46 is
fixedly secured to a flange portion 50 of pressure plate 34 by a fastener
52, such as a rivet or the like. A second end 54 of second drive strap 46
is removably connected to cover 22 by a fastener 56, such as a threaded
bolt or the like. A washer 58 may be disposed between a head 59 of
fastener 56 and second drive strap 46 to ensure adequate contact pressure
is distributed over second end 54 of second drive strap 46.
Referring still to FIG. 2, a first end 60 of first drive strap 44 is
fixedly secured to intermediate plate 28, while a second end 62 of first
drive strap 44 is removably connected to cover 22. To facilitate easy
removal of intermediate plate 28 from clutch 20, first drive strap 44 is
preferably attached to cover 22 by a threaded fastener 64, such as a
threaded bolt or the like. Once secured to cover 22, a significant portion
of threaded fastener 64 extends beyond cover 22. This "extended" portion
of threaded fastener 64 is preferably provided with a generally
cylindrical sleeve 66 that extends between first drive strap 44 and a head
68 of threaded fastener 64. A washer 70, such as a beveled washer, may be
provided between sleeve 66 and first drive strap 44 to increase the
clamping force applied by threaded fastener 64 against first drive strap
44. Similarly, a generally flat washer 72 may be provided between head 68
and sleeve 66, or a flange may be provided on head 68, to ensure that
sufficient contact pressure is distributed from head 68 through the
fastened components.
Intermediate plate 28 preferably includes a lug portion 74 through which
threaded fastener 64 and sleeve 66 extend to moveably secure intermediate
plate 28 to cover 22. As illustrated in FIG. 2, lug portion 74 is provided
with an aperture 76 therethrough that is sized to slidingly receive sleeve
66, so that intermediate plate 28 is free to slide on sleeve 66 during
operation. The length of sleeve 66, or the degree of axial movement
afforded to intermediate plate 28, will generally depend on various
factors, including, but not limited to, the size of clutch 20 and the
amount of travel needed to compensate for wear in first friction disk 26.
However, care must be taken to ensure that the axial movement afforded
intermediate plate 28 does not permanently deform or otherwise damage
first drive strap 44. Accordingly, washer 72 acts as a "stop" against
which intermediate plate 28 is precluded from further axial travel.
First end 60 of first drive strap 44 is fixedly secured to intermediate
plate 28 by a fastener 78, such as a rivet or the like. Fastener 78 is
also used to attach a separator arm 79 to intermediate plate 28 for
movement therewith. In a preferred embodiment, separator arm 79 is made of
a relatively high strength material, such as metal or plastic, and
includes a base portion 80 secured to intermediate plate 28 and a head
portion 82 that engages second drive strap 46. Head portion 82 preferably
engages second drive strap 46 proximate a mid-point between fastener 52
and fastener 56, for reasons that will be explained below, but may engage
other points on second drive strap 46 as required. Head portion 82
preferably includes a substantially flat land 77 where it contacts second
drive strap 46 to reduce contact pressure and friction.
Referring to FIGS. 3A and 3B, base portion 80 includes an aperture 84
therethrough that is sized to receive fastener 78 and a lip 86 that
extends along at least a portion of base 80. Once assembled onto
intermediate plate 28, lip 86 abuts first drive strap 44 and substantially
prevents rotation of separator arm 79 about a longitudinal axis (not
shown) of fastener 78 during operation of clutch 20. Alternatively, lip 86
may take other forms, such as, for example, lip 86' illustrated in FIGS.
4-8.
Referring to FIG. 4, an alternate embodiment of the present invention is
shown in detail. In this embodiment, a clutch 20' is provided that is
substantially similar to clutch 20 described in the first embodiment with
a least one exception, namely, the configuration of separator arm 79. In
this embodiment, a separator arm 79' is provided that includes a separate
base portion 80' that is secured to a head portion 82' prior to assembly
of separator arm 79' onto intermediate plate 28. As illustrated in FIG.
5A, head portion 82' may be secured to base portion 80' by press fitting a
shaft 87 on head portion 82' into an aperture 88 in base portion 80'.
Alternatively, other methods may be used to secure head portion 82' to
base portion 80', such as using snap hooks, as illustrated in FIG. 5B, or
welding head portion 82' to base portion 80'. An advantage of the
embodiment illustrated in FIG. 4 is that head portion 82' can be
manufactured out of a low friction material, such as PTFE, whereas base
portion 80' can be manufactured out of a second, perhaps less costly
material.
Referring to FIGS. 6, 7 and 9, another alternate embodiment of the present
invention is shown in detail. In this embodiment, a separator arm 79" is
provided that includes a generally round head portion 82", as opposed to
substantially flat head portion 82 provided in the preferred embodiment.
Separator arm 79" provides a concentrated point of contact between head
portion 82" and second drive strap 46, which more precisely defines the
axial movement of intermediate plate 28.
Optionally, in clutch assemblies that exhibit a relatively high level of
friction between separator arm 79" and second drive strap 46, a friction
reducing member 90 may be disposed between second drive strap 46 and head
portion 82", as illustrated in FIG. 7. However, friction reducing member
90 is not necessary due to the friction reducing characteristics of
separator arm 79 and adequate control of the displacements of intermediate
plate 28 and pressure plate 34 can be achieved with the simplified
intermediate plate control system.
Referring to FIG. 8, friction reducing member 90 includes a contoured
surface 92 that engages head portion 82" and a duct 94 therethrough for
receiving second drive strap 46. Friction reducing member 90 may be
manufactured out of any suitable friction reducing material, such as PTFE.
Referring to FIGS. 9 and 10, an alternate embodiment of friction reducing
member 90 is shown in detail. In this embodiment a friction reducing
member 90' is provided that includes a pair bendable clamps 96 that are
bent around second drive strap 46 and an contoured portion 98 that engages
head portion 82". An advantage of this embodiment is that can be more cost
effectively manufactured, such as by stamping the shape of friction
reducing member 90' out of a suitable metal.
Advantages of the present invention will become apparent upon review of the
assembly and operation of clutch 20, as described herein below. In the
assembly of clutch 20, first clutch disk 26 is moved into contact with
flywheel 24 and then a pre-assembled cover assembly, which includes
intermediate plate 28, second friction disk 30, pressure plate 34,
diaphragm spring 40 and cover 22, are secured to flywheel 24. Cover 22 may
be divided into two parts for simpler assembly and disassembly of the
intermediate plate 28, however, such a division of cover 22 is not
necessary.
When clutch 20 is disengaged, that is, when diaphragm spring 40 is moved to
the position shown in FIG. 1, pressure plate 34 automatically moves away
from flywheel 24 due to the biasing force of second drive strap 46.
Virtually simultaneously, intermediate plate 28 automatically moves away
from flywheel 24 due to the biasing force of first drive strap 44.
However, due to the contact of separator arm 79 proximate the mid-point of
second drive strap 46, the axial distance intermediate plate 28 moves is
approximately one-half the axial distance pressure plate 34 moves. In this
manner, it is ensured that first and second friction disks 26, 30 are
disengaged virtually simultaneously. It will be appreciated that axial
movement of intermediate plate 28 relative to pressure plate 34 can be
easily modified by altering the point of engagement between separator arm
79 and second drive strap 46. For example, the dimensions of separator arm
79 can be modified to alter the engagement point of separator arm 79 on
second drive strap 46.
When clutch 20 is engaged, the various components move in a direction
opposite the direction of disengagement, i.e., to the left in FIG. 1.
Again, due to the engagement of separator arm 79 with second drive strap
46, intermediate plate 28 will move approximately one-half the distance
pressure plate 34 moves. In this manner, it is ensured that first and
second friction disks 26, 30 are engaged virtually simultaneously and
smoothly, due to axial movement of intermediate plate 28 relative to cover
22 being a precisely defined fraction of the corresponding axial movement
of pressure plate 34. Additionally, axial movement of intermediate plate
28, and indirectly pressure plate 34, is limited by fasteners 64 to
substantially prevent first and second drive straps 44, 46 from becoming
damaged due to excessive wear in friction disk 26, 30.
Among other advantages, separator arm 79 can be attached to intermediate
plate 28 using existing fasteners, i.e., fastener 78 used to secure first
drive strap 44 to intermediate plate 28, thereby eliminating one or more
manufacturing steps. Another advantage is that the material of separator
arm 79, more particularly head portion 82, can be easily tailored to the
requirements of a particular clutch assembly to reduce friction between
separator arm 79 and second drive strap 46, and decrease component wear.
Unlike the prior art, separator arm 79 can be engaged directly with second
drive strap 46, without the use of a lever. Still another advantage is
that intermediate plate 28 can be easily removed from clutch 20 to
facilitate repair or replacement of friction disks 23, 30. Yet another
advantage is that axial movement of intermediate plate 28 is precisely
controlled by fasteners 64 to prevent damage to first and second drive
straps 44, 46 during operation of clutch 20.
Although certain preferred embodiments of the present invention have been
described, the invention is not limited to the illustrations described and
shown herein, which are deemed to be merely illustrative of the best modes
of carrying out the invention. A person of ordinary skill in the art will
realize that certain modifications and variations will come within the
teachings of this invention and that such variations and modifications are
within its spirit and the scope as defined by the claims.
*
