Title of Invention

A CLUTCH FOR A TRANSMISSION

Abstract The disclosed clutch includes a reaction plate, a friction plate, a friction layer, at least one non-compressible member and a fluid lubricant. The friction layer has a coefficient of friction that is sufficient to prevent relative rotation of the reaction and friction plates when the friction layer is compressed by the reaction plate. Further, the friction layer has at least one groove. At least one non-compressible member is disposed in the at least one groove to prevent further compression of the friction layer by the reaction plate. The at least one non-compressible member is mechanically fastened to the friction plate.
Full Text Attorney Docket No. P000022-PTT-DLT
A CLUTCH FOR A TRANSMISSION
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S. Provisional
Application No. 60/862,829, filed on October 25, 2006. The disclosure of the above
application is incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a torque-transmitting device and to
clutches or brakes for controlling the operation of mechanisms such as transmissions or
limited slip differentials.
BACKGROUND
[0003] Torque transmitting devices such as clutches or brakes are used
throughout the automotive industry. For example, vehicle transmissions employ multiple
clutches to engage and disengage the gearsets of the transmission to provide forward and
reverse gear ratios.
[0004] Generally, a clutch includes a friction plate and a reaction plate. The
friction plate has a layer of friction material attached to the surface that opposes the
reaction plate. Conventional friction materials are (a) cellulose/Kevlar/resin based
materials; (b) sintered and/or metallic friction materials; and (c) woven carbon fiber
friction materials.
[0005] Attempts have been made to use woven carbon fiber as a friction
material for shifting/launch clutches. Carbon fiber material is typically more durable
and has higher thermal conductivity as well as permeability in comparison with
cellulose-based material, which favorably affect the friction characteristics of the
clutch. The carbon fiber woven friction material is attached to the core steel plate by
polymer-based adhesive. The adhesive has low thermal conductivity.
[0006] US Patent 6,360,864 ('864) issued March 26, 2002 to Ford Global
Technologies Inc, of Dearborn, MI attempts to decrease the instant temperature of the
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Attorney Docket No. P000022-PTT-DLT
lubrication fluid in the clutch. The '864 patent increasing the area of contact between
the fluid and steel reaction plates by providing either internal channels open for the
fluid to flow through the reaction plate or having reaction plate split into two halves
with a spacer between in an attempt to decrease the instant lubrication fluid
temperature.
[0007] While the device of the '864 patent and other prior art devices work for
their intended purpose improvements are still needed. For example, it would be
desirable to provide a device that reduces the temperature of the lubricating fluid and
addresses clutch overloading.
SUMMARY
[0008] In an aspect of the present invention a clutch is provided. The clutch
includes a reaction plate, a friction plate, a friction layer, at least one non-compressible
member and a fluid lubricant. The reaction plate is configured to provide a compression
force. The friction plate is disposed adjacent the reaction plate and configured to
frictionally engaging the reaction plate to transfer a driving torque between the reaction
plate and the friction plate when the compression force is applied. The friction layer is
attached to the friction plate opposite the reaction plate. The friction layer has a
coefficient of friction that is sufficient to prevent relative rotation of the reaction and
friction plates when the friction layer is compressed by the reaction plate. Further, the
friction layer has at least one groove. Additionally, at least one non-compressible
member is disposed in the at least one groove to prevent further compression of the
friction layer by the reaction plate. The at least one non-compressible member is
mechanically fastened to the friction plate. The fluid lubricant is disposed between the
reaction plate and the friction plate and provides a lubrication layer between the plates.
[0009] In another aspect of the present invention, the mechanical fastening of
the at least one non-compressible member to the friction plate provides a conductive
heat flow path from the lubrication fluid through the at least one non-compressible
member to the friction plate.
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Attorney Docket No. P000022-PTT-DLT
[0010] In yet another aspect of the present invention, the at least one non-
compressible member is mechanically fastened to the friction plate by rivets.
[0011] In yet another aspect of the present invention, the three grooves in the
friction layer have three non-compressible members disposed in each of the three grooves
for preventing further compression of the friction layer by the reaction plate.
[0012] In still another aspect of the present invention, the at least one non-
compressible member is made primarily of metal.
[0013] In still another aspect of the present invention, the friction layer is made
primarily of a porous material that allows the lubricating fluid to move through the
friction layer.
[0014] In still another aspect of the present invention, the friction layer is a
compressible resilient material that will return to an initial height of the friction layer
prior to being compressed by the reaction plate.
[0015] In still another aspect of the present invention, the friction layer is made
substantially of a woven carbon fiber.
[0016] In still another aspect of the present invention, the at least one non-
compressible member has a height that is less than a thickness of the friction layer before
the friction layer is compressed by the reaction plate.
[0017] In still another aspect of the present invention, the at least one non-
compressible member has a predefined height that prevents the friction layer from being
plastically deformed.
[0018] In another aspect of the present invention, the at least one non-
compressible member has a predefined height that is substantially equal to the thickness
of the friction material layer after the friction layer has been compressed when the
clutch is in a high speed slip operating condition.
[0019] In another aspect of the present invention, the at least one non-
compressible member has a predefined height that is greater than the thickness of the
friction material layer after the friction layer has been compressed when the clutch is in a
low speed slip operating condition.
[0020] Further areas of applicability will become apparent from the description
provided herein. It should be understood that the description and specific examples are
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Attorney Docket No. P000022-PTT-DLT
intended for purposes of illustration only and are not intended to limit the scope of the
present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIGURE 1 is a side view of a torque transmitting device connected
between a drive shaft and a driven shaft, in accordance with an embodiment of the
present invention;
[0022] FIGURE 2 is a partial cutaway view of the torque transmitting device of
Figure 1 having mechanically secured inserts, in accordance with an embodiment of the
present invention;
[0023] FIGURE 3a is a cross-sectional view of the torque transmitting device of
Figure 1 having mechanically secured inserts at a location shown in Figure 2 and in an
initial engagement condition, in accordance with an embodiment of the present invention;
[0024] FIGURE 3b is a magnified cross-sectional view of the torque transmitting
device of Figure 1 having mechanically secured inserts at a location shown in Figure 3a,
in accordance with an embodiment of the present invention;
[0025] FIGURE 4 is a cross-sectional view of the torque transmitting device of
Figure 1 having mechanically secured inserts at a location shown in Figure 2 and in a
high speed slip condition, in accordance with an embodiment of the present invention;
and
[0026] FIGURE 5 is a cross-sectional view of the torque transmitting device of
Figure 1 having mechanically secured inserts at a location shown in Figure 2 and in a low
speed slip condition, in accordance with an embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Referring to the drawings, wherein like reference numbers refer to like
components, in Figure 1 a side view of a torque-transmitting device 10 is illustrated, in
accordance with an embodiment of the invention. Torque-transmitting device 10 is
commonly referred to in automotive applications as a clutch or brake. Device 10 has a
first plate or friction plate 12 and a second plate or reaction plate 16. Friction plate 12 is
separated from reaction plate 16 by a layer of lubrication fluid 14. Fluid lubricant 14
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Attorney Docket No. P000022-PTT-DLT
disposed between the reaction plate 16 and the friction plate 12 provides a lubrication
barrier between the plates. Torque-transmitting device 10 is connected between a drive
shaft 28 and a driven shaft 30. More specifically, friction plate 12 is coupled to drive
shaft 28 and reaction plate 16 is coupled to driven shaft 30. Drive shaft 28 is typically
connected to a torque-producing device such as an internal combustion engine (not
shown). Driven shaft 30 may be connected to a planetary gearset (not shown) for
transmitting a driving torque from the engine to the planetary gearset to drive the road
wheels of a vehicle. Both friction plate 12 and reaction plate 16 are planar and have a
substantially circular shape. Further, plates 12 and 16 are made of steel or similar
material. However, the teachings of the present invention may be applied to plates made
of other materials, such as metal alloys, composites and the like.
[0028] Referring now to Figure 2, a partial cutaway view of the torque
transmitting device 10 of Figure 1 is illustrated, in accordance with an embodiment of the
present invention. Portions of reaction plate 16 have been removed to reveal the
lubrication layer 14 and a friction material layer 36. Friction material layer 36 is adhered
to a surface of the friction plate 12. Friction material layer 36 is one of a variety of
friction materials currently in use in torque transmitting mechanisms today. For example,
in an embodiment of the invention friction material layer 36 is the friction material shown
and described in US patent number 5,676,577 issued to Robert Chi-Chiu Lam and Yih
Fang Chen and assigned to Borg-Warner Automotive, Inc of Sterling Heights, MI, and
hereby incorporated by reference. Further, friction material layer 36 may be made of a
friction material offered by Borg-Warner Automotive, Inc of Sterling Heights. MI
having the product identification number BW-6500. However, the present invention
contemplates that friction material layer 36 is made of cellulose, Kevlar, resin, sintered
metal, woven carbon fiber or any combination of these materials in varying percentages
by weight that may or may not be in use in clutch applications currently. Friction
material layer 36 is a porous layer that allows lubricating fluid 14 to move through layer
36. Further, friction material layer 36 is a compressible resilient material that will return
to its initial height and shape prior to being compressed by reaction plate 16, if layer 36 is
not compressed beyond its elastic limit. In a preferred embodiment of the present
invention friction layer 36 is made of woven carbon fiber.
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Attorney Docket No. P000022-PTT-DLT
[0029] In another embodiment of the present invention, grooves 38 are formed in
friction material layer 36. The depth of grooves 38 is substantially equal to the thickness
of the friction material layer 36. Preferably, at least three grooves are formed in friction
material layer 36. However, the present invention contemplates that fewer than three or
more than three grooves maybe formed in friction material layer 36. Moreover, grooves
38 are spaced apart and disposed circumferentially around friction plate 12. The present
invention contemplates that grooves 38 are formed to extend radially out from the center
of plate 12 or are disposed on an angle relative to a line passing through the center of
plate 12 and extending radially outward.
[0030] Further, in a preferred embodiment of the present invention, a ridge or
insert member 40 is placed in each of the grooves 38. Insert member 40, for example is a
separate component that is mechanically fastened to friction plate 12. Insert member 40
is made of carbon fiber, steel, a metal alloy or similar material. In an embodiment of the
present invention, the width Wi of the insert members 40 is no wider than a typical
lubrication fluid groove width in a conventional friction plate. Furthermore, width Wi of
insert 40 is dimensioned to be sufficient to accommodate any overloading received from
clutch engagement.
[0031] In a preferred embodiment of the present invention, insert members 40
have a plurality of apertures 42 through which rivets 43 are passed to mechanically fasten
insert members 40 to friction plate 12, as shown in Figure 3a and the magnified view of
Figure 3b. Further, rivets 43 are positioned in recess apertures 45 to locate the head of
the rivet below top surfaces 47 of insert members 40. Rivets 43 have hollow center
tubular members 49 that are configured to receive and transport lubrication fluid 14 to the
interface of the friction plate 12 and reaction plate 16. The mechanical fastening of
insert members 40 to friction plate 12 provides a conductive heat flow path from the
lubrication fluid 14 through insert members 40 to friction plate 12. Moreover, the overall
effective surface area of the friction plate 12 is significantly increased to enhance cooling
of lubrication fluid 14. Of course, the present invention contemplates the use of other
mechanical fasteners such as, bolts, screws and the like.
[0032] With continuing reference to 3a, a cross-sectional view of the torque-
transmitting device 10 of Figure 1 at a location shown in Figure 2 and at initial
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Attorney Docket No. P000022-PTT-DLT
engagement is illustrated, in accordance with an embodiment of the present invention. At
initial engagement, friction material layer 36 preferably has an uncompressed thickness
Tuc that is greater than the height Hi of insert members 40. Thus, grooves 38 exist at
initial engagement. Grooves 38 promote the flow of lubrication fluid 14 through torque
transmitting device 10 and work to break through the hydrodynamic film and avoid
hydroplaning. An important characteristic of friction material layer 36 is the elastic
property of layer 36. More specifically, friction material layer 36 has an elastic zone Ez
that extends from its uncompressed thickness Tuc to just below the height of the insert
members 40. as referenced in Figure 3a. When friction material layer 36 is compressed
to a thickness such that the top surface of friction material layer 36 is within elastic zone
Ez, layer 36 will remain resilient and return to its initial thickness when uncompressed.
Further, insert members 40 are specifically configured to ensure that friction material
layer 36 is not compressed below elastic zone Ez by preventing reaction plate 16 from
moving closer to friction plate 12. In other words, friction plate 12 and reaction plate 16
will move towards each other until reaction plate 16 contacts insert members 40 attached
to friction plate 12.
[0033] As shown in Figure 4, a cross-sectional view of the torque transmitting
device 10 of Figure 1 at a location shown in Figure 2 and during high speed slip, in
accordance with an embodiment of the present invention. As the load on reaction plate
16 reaches its maximum capacity grooves 38 will disappear, friction material layer 36
will transfer the majority of the torque in elastic deformation region with initial or close
to initial permeability, and insert members 40 will carry some of the torque. More
specifically, during high-speed slip friction material layer 36 is compressed such that
the thickness Ths of the friction material is substantially equal to the height of insert
members 40. In this condition, grooves 38 are no longer present. Insert members 40
have a predefined height Hi that prevents friction material layer 12 from being
compressed beyond its elastic deformation range or zone Ez. Moreover, insert
members 40 will provide parallelism between friction plate 12 and reaction plate 16
resulting in an enhanced load distribution. Further, insert members 40 will absorb any
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Attorney Docket No. P000022-PTT-DLT
additional temporary loading, thus avoiding friction material plastic deformation and
permeability loss.
[0034] Reference is now made to Figure 5, a cross-sectional view of the torque-
transmitting device 10 of Figure 1 at a location shown in Figure 2 and during low speed
slip. During low speed slip friction material layer 36 is compressed such that the
thickness Tis of the friction material is slightly below the height of insert members 40.
In this condition, grooves 38 are no longer present. Moreover, friction material layer
36 during low speed slip is fully compressed and at its elastic deformation limit. If
friction material layer 36 were compressed beyond its elastic deformation limit, layer
36 would enter plastic deformation. Friction material layer 36 would lose its resilience
if it enters plastic deformation. However, the present invention ensures that friction
material layer will not be plastically deformed by providing insert members 40 having a
predefined height Hi that prevents reaction plate 16 from further compressing friction
material layer 36 beyond its elastic deformation zone Ez.
[0035] Thus, the present invention has many advantages and benefits over the
prior art. Moreover, the teachings of the present invention may be employed to
overcome many problems found in prior art torque-transmitting devices. For example,
the present invention overcomes the problem of shudder and other problems discussed
in a technical paper authored by Robert C. Lam, Bulent Chavdar, and Tim Newcomb,
New Generation Friction Materials and Technologies and published by The Society of
Automotive Engineers (Ref. # SAE 2006-01-0150), hereby incorporated by reference.
Further, the increase in surface area of the metal friction plate in contact with the
lubrication fluid during clutch engagement significantly decreases the maximum instant
fluid temperature of the lubrication fluid. Advantageously, the clutch of the present
invention reduces the maximum instant temperature of the lubricating fluid, which in
turn reduces the depletion rate of the high pressure/high temperature additives needed
to minimize the static friction coefficient and avoid shudder. Thus, with the same
amount of lubrication fluid flow and the same transmission configuration, the fluid
temperature is reduced due to enhanced heat transfer. Additionally, the lower
temperature of the lubrication fluid provides higher EHD friction and thicker film at the
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Attorney Docket No. P000022-PTT-DLT
low relative velocities due to an increase in viscosity, while decreasing the depletion
rate of the high pressure/high temperature additives needed to minimize the static
friction coefficient.
[0036] While the best modes for carrying out the invention have been described
in detail, it is to be understood that the terminology used is intended to be in the nature of
words and description rather than of limitation. Those familiar with the art to which this
invention relates will recognize that many modifications of the present invention are
possible in light of the above teachings. It is, therefore, to be understood that within the
scope of the appended claims, the invention may be practiced in a substantially
equivalent way other than as specifically described herein.
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Attorney Docket No. P000022-PTT-DLT
CLAIMS
1. A clutch comprising:
a reaction plate for exerting a compression force;
a friction plate disposed adjacent the reaction plate for frictionally engaging the
reaction plate to transfer a driving torque between the reaction plate and the friction plate
when the compression force is applied;
a friction layer attached to the friction plate and opposing the reaction plate, the
friction layer has a coefficient of friction that is sufficient to prevent relative rotation of
the reaction and friction plates when the friction layer is compressed by the reaction
plate, and wherein the friction layer has at least one groove;
at least one non-compressible member disposed in the at least one groove for
preventing further compression of the friction layer by the reaction plate, wherein the at
least one non-compressible member is mechanically fastened to the friction plate; and
a fluid lubricant disposed between the reaction plate and the friction plate for
providing a lubrication layer between the plates.
2. The clutch of claim 1 wherein the mechanical fastening of the at least one
non-compressible member to the friction plate provides a conductive heat flow path from
the lubrication fluid through the at least one non-compressible member to the friction
plate.
3. The clutch of claim 2 wherein the at least one non-compressible member
is mechanically fastened to the friction plate by rivets.
4. The clutch of claim 1 further comprising three grooves in the friction layer
having three non-compressible members disposed in each of the three grooves for
preventing further compression of the friction layer by the reaction plate.
5. The clutch of claim 1 wherein the at least one non-compressible member
is made primarily of metal.
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Attorney Docket No. P000022-PTT-DLT
6. The clutch of claim 1 wherein the friction layer is made primarily of a
porous material that allows the lubricating fluid to move through the friction layer.
7. The clutch of claim 6 wherein the friction layer is a compressible resilient
material that will return to an initial height of the friction layer prior to being compressed
by the reaction plate.
8. The clutch of claim 6 wherein the friction layer is made substantially of a
woven carbon fiber.
9. The clutch of claim 1 wherein the at least one non-compressible member
has a height that is less than a thickness of the friction layer before the friction layer is
compressed by the reaction plate.
10. The clutch of claim 1 wherein the at least one non-compressible member
has a predefined height that prevents the friction layer from being plastically deformed.
11. The clutch of claim 1 wherein the at least one non-compressible member
has a predefined height that is substantially equal to the thickness of the friction material
layer after the friction layer has been compressed when the clutch is in a high speed slip
operating condition.
12. The clutch of claim 1 wherein the at least one non-compressible member
has a predefined height that is greater than the thickness of the friction material layer
after the friction layer has been compressed when the clutch is in a low speeds slip
operating condition

11

The disclosed clutch includes a reaction plate, a friction plate, a friction layer, at
least one non-compressible member and a fluid lubricant. The friction layer has a
coefficient of friction that is sufficient to prevent relative rotation of the reaction and
friction plates when the friction layer is compressed by the reaction plate. Further, the
friction layer has at least one groove. At least one non-compressible member is disposed
in the at least one groove to prevent further compression of the friction layer by the
reaction plate. The at least one non-compressible member is mechanically fastened to the
friction plate.

Documents:

01131-kol-2007-abstract.pdf

01131-kol-2007-assignment.pdf

01131-kol-2007-claims.pdf

01131-kol-2007-correspondence others 1.1.pdf

01131-kol-2007-correspondence others 1.2.pdf

01131-kol-2007-correspondence others 1.3.pdf

01131-kol-2007-correspondence others.pdf

01131-kol-2007-description complete.pdf

01131-kol-2007-drawings.pdf

01131-kol-2007-form 1.pdf

01131-kol-2007-form 18.pdf

01131-kol-2007-form 2.pdf

01131-kol-2007-form 3.pdf

01131-kol-2007-form 5.pdf

01131-kol-2007-priority document.pdf

1131-KOL-2007-(01-09-2011)-ASSIGNMENT.pdf

1131-KOL-2007-(01-09-2011)-FORM 16.pdf

1131-KOL-2007-(01-09-2011)-PA.pdf

1131-KOL-2007-ABSTRACT 1.1.pdf

1131-KOL-2007-AMANDED CLAIMS.pdf

1131-KOL-2007-AMANDED PAGES OF SPECIFICATION.pdf

1131-KOL-2007-CORRESPONDENCE 1.4.pdf

1131-KOL-2007-CORRESPONDENCE-1.5.pdf

1131-KOL-2007-DESCRIPTION (COMPLETE) 1.1.pdf

1131-KOL-2007-DRAWINGS 1.1.pdf

1131-KOL-2007-EXAMINATION REPORT REPLY RECIEVED.pdf

1131-KOL-2007-FORM 1-1.1.pdf

1131-KOL-2007-FORM 2-1.1.pdf

1131-KOL-2007-FORM 3-1.1.pdf

1131-KOL-2007-OTHERS 1.1.pdf

1131-KOL-2007-OTHERS.pdf

1131-KOL-2007-PA.pdf

1131-KOL-2007-PETITION UNDER RULE 137.pdf

abstract-01131-kol-2007.jpg


Patent Number 247880
Indian Patent Application Number 1131/KOL/2007
PG Journal Number 22/2011
Publication Date 03-Jun-2011
Grant Date 30-May-2011
Date of Filing 16-Aug-2007
Name of Patentee GM GLOBAL TECHNOLOGY OPERATIONS, INC.
Applicant Address 300 GM RENAISSANCE CENTER DETROIT, MICHIGAN
Inventors:
# Inventor's Name Inventor's Address
1 GREGORY MORDUKHOVICH 1997 KLINGENSMITH ROAD NUMBER 54 BLOOMFIELD HILLS, MICHIGAN 48302
PCT International Classification Number G12B3/06
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/862,829 2006-10-25 U.S.A.