U.S. patent application number 09/734277 was filed with the patent office on 2001-07-05 for thrust plate assembly.
This patent application is currently assigned to Mannesmann Sachs AG. Invention is credited to Lindner, Joachim, Weidinger, Reinhold.
Application Number | 20010006140 09/734277 |
Document ID | / |
Family ID | 7932142 |
Filed Date | 2001-07-05 |
United States Patent
Application |
20010006140 |
Kind Code |
A1 |
Lindner, Joachim ; et
al. |
July 5, 2001 |
Thrust plate assembly
Abstract
A thrust plate assembly for a motor vehicle friction clutch with
automatic wear compensation includes a housing fixedly connectable
to a flywheel for joint rotation with the flywheel about an axis of
rotation, a pressure plate arranged in the housing such that the
pressure plate is fixed with respect to rotation relative to the
housing and axially displaceable relative to the housing, an energy
accumulator such as a diaphragm spring having one side supported at
the housing and another side supported at the pressure plate, and a
wear adjustment device arranged in the support path of the energy
accumulator between the energy accumulator and a component of the
housing and pressure plate. The wear adjustment device has at least
one adjustment element which is displaceable to compensate for wear
and is operatively arranged for effecting wear compensation in
proportion to the occurring wear. The ratio of movement of the wear
adjustment device to the amount of occurring wear differs from
1:1.
Inventors: |
Lindner, Joachim;
(Dittelbrunn, DE) ; Weidinger, Reinhold;
(Unterspiesheim, DE) |
Correspondence
Address: |
Thomas C. Pontani, Esq.
Cohen, Pontani, Lieberman & Pavane
Suite 1210
551 Fifth Avenue
New York
NY
10176
US
|
Assignee: |
Mannesmann Sachs AG
|
Family ID: |
7932142 |
Appl. No.: |
09/734277 |
Filed: |
December 11, 2000 |
Current U.S.
Class: |
192/70.252 |
Current CPC
Class: |
F16D 13/757 20130101;
F16D 2013/581 20130101 |
Class at
Publication: |
192/111.00A ;
192/70.25 |
International
Class: |
F16D 013/75 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 10, 1999 |
DE |
199 59 584.4 |
Claims
We I claim:
1. A thrust plate assembly for a motor vehicle friction clutch with
automatic wear compensation, comprising: a housing fixedly
connectable to a flywheel for joint rotation with the flywheel
about an axis of rotation; a pressure plate arranged in said
housing so that said pressure plate is fixed with respect to
rotation relative to said housing and axially displaceable relative
to said housing; an energy accumulator having one side supported at
said housing and another side supported at said pressure plate; and
a wear adjustment device arranged in a support path of said energy
accumulator between said energy accumulator and a component of one
of said housing and said pressure plate, wherein said wear
adjustment device includes at least one adjustment element
displaceable to compensate for wear and said wear adjustment device
is operatively arranged for effecting a wear compensation in
proportion to the occurring wear, wherein a ratio of said wear
compensation effected by said wear adjustment device to said
occurring wear differs from 1:1.
2. The thrust plate assembly of claim 1, wherein said at least one
adjustment element is movable in a wear adjustment movement
direction corresponding to the occurring wear, wherein a movement
of said at least one adjustment element in said wear adjustment
movement direction displaces said at least one adjustment element
in a compensating movement direction different than the wear
adjustment movement direction, and wherein an extent of movement in
the compensating movement direction for wear to the amount of
occurring wear is in a ratio other than 1:1.
3. The thrust plate assembly of claim 2, wherein said at least one
adjustment element comprises a first surface so that when said at
least one wear adjustment element is moving in the wear adjustment
movement direction, said first surface moves along a
counter-surface, wherein one of said first surface and said
counter-surface is inclined in the wear adjustment movement
direction, and wherein an angle of inclination of said at least one
of said first surface and counter-surface is selected such that the
extent of movement in the compensating movement direction to the
amount of occurring wear is in a ratio to wear other than 1:1.
4. The thrust plate assembly of claim 2, further comprising at
least one play sensor arrangement arranged on a further component
of said thrust plate assembly for detecting wear and a blocking
element, said blocking element being displaceable relative to said
further component in response to the occurring wear, wherein said
at least one play sensor arrangement comprises a detection element
having a detection portion arrangeable for interacting with said
blocking element for detecting wear, wherein said detection element
is displaceable to a position corresponding to the occurring wear
by interaction with said blocking element, said thrust plate
assembly further comprising a stopping element operatively arranged
for stopping said detection element in the position corresponding
to the occurring wear.
5. The thrust plate assembly of claim 4, wherein said stopping
element is displaceable in a stopping movement direction by a
movement extent corresponding to the occurring wear to stop said
detection element in the position corresponding to the occurring
wear, and wherein said stopping element comprises a blocking member
operatively arranged for cooperating with said at least one
adjustment element to limit the movement of said at least one
adjastment element in said wear adjustment movement direction to an
extent corresponding to the occurring wear.
6. The thrust plate assembly of claim 5, wherein said wear
adjustment movement direction and said stopping movement direction
are the same direction.
7. The thrust plate assembly of claim 6, wherein said stopping
movement direction and said wear adjustment movement direction
comprise a circumferential movement direction.
8. The thrust plate assembly of claim 6, wherein said blocking
member comprises a stop acting in said wear adjustment movement
direction.
9. The thrust plate assembly of claim 4, wherein said at least one
adjustment element comprises a first surface so that when said at
least one wear adjustment element is moving in the wear adjustment
movement direction, said first surface moves along a
counter-surface, wherein one of said first surface and said
counter-surface is inclined in the wear adjustment movement
direction, and wherein an angle of inclination of said at least one
of said first surface and counter-surface is selected such that the
extent of movement in the compensating movement direction to the
amount of occurring wear is in a ratio to wear other than 1:1, and
wherein said stopping element comprises a wedge-shaped element with
a wedge angle, said wedge angle of said stopping element being
different from an angle of inclination of said at least one of said
first surface and counter-surface.
10. The thrust plate assembly of claim 9, wherein one of said wedge
angle of said stopping element in said stopping movement direction
and said angle of inclination of said at least one of said first
surface and counter-surface in said wear adjustment direction is
not constant.
11. The thrust plate assembly of claim 1, wherein said ratio is in
the range including 0.6 to 0.95.
12. The thrust plate assembly of claim 1, wherein said ratio
changes as a compensation of wear increases.
13. The thrust plate assembly of claim 12, wherein said ratio
increases as the compensation of wear increases.
14. A thrust plate assembly for a motor vehicle friction clutch
with automatic wear compensation, comprising: a housing fixedly
connectable to a flywheel for joint rotation with the flywheel
about an axis of rotation; a pressure plate arranged in said
housing so that said pressure plate is fixed with respect to
rotation relative to said housing and axially displaceable relative
to said housing; an energy accumulator having one side supported at
said housing and and another side supported at said pressure plate;
a wear adjustment device arranged in the support path of said
energy accumulator between said energy accumulator and a component
of one of said housing and said pressure plate, said wear
adjustment device having at least one adjustment element
displaceable to compensate for wear, wherein said at least one
adjustment element is pretensioned for movement in a wear
adjustment movement direction, wherein said at least one adjustment
element comprises a surface which moves along a counter-surface
when said at least one adjustment element moves in said wear
adjustment movement direction, wherein one of said surface and said
counter-surface is inclined in the wear adjustment movement
direction; at least one blocking member operatively arranged for
blocking said at least one adjustment element to prevent movement
of said at least one adjustment element in the wear adjustment
movement direction; and at least one play sensor arrangement for
detecting occurring wear and a blocking element displaceable with
respect to another component of said thrust plate assembly in
response to occurring wear, wherein said at least one play sensor
arrangement comprises a detection element arrangeable for
interacting with said blocking element and said detection element
is displaceable to a position corresponding to the occurring wear
by the interaction with said blocking element, said at least one
play sensor arrangement further comprising a stopping element
operatively arranged for stopping said detection element in the
position corresponding to the occurring wear, and wherein said at
least one blocking member is arranged on said stopping element.
15. The thrust plate assembly of claim 14, wherein said at least
one blocking member is arrangeable for interacting with said at
least one adjustment element to block said at least one adjustment
element in said wear adjustment movement direction.
16. The thrust plate assembly of claim 14, wherein said
counter-surface is formed at said component of one of said housing
and said pressure plate.
17. The thrust plate assembly of claim 14, wherein said at least
one detection element is arranged at said component of one of said
housing and said pressure plate and further comprises a detection
portion operatively arranged for interacting with said one of said
component and subassembly.
18. The thrust plate assembly of claim 14, wherein at least a
portion of said detection element is arranged between said at least
one adjustment element and said pressure plate.
19. The thrust plate assembly of claim 17, wherein said at least
one adjustment element comprises an adjustment ring arranged
substantially concentric to the axis of rotation, said component of
one of said housing and said pressure plate comprises said pressure
plate, and said detection portion projects through an intermediate
space formed between said adjustment ring and said pressure
plate.
20. The thrust plate assembly of claim 14, wherein said stopping
element is displaceable in a stopping movement direction by a
movement amount corresponding to the occurring wear to stop said
detection element in the position corresponding to the occurring
wear.
21. The thrust plate assembly of claim 20, wherein said at least
one adjustment element moves in a wear adjustment movement
direction and said stopping element moves in a stopping movement
direction, and wherein said wear adjustment movement direction and
said stopping movement direction are in the same direction.
22. A friction clutch comprising a thrust plate assembly, wherein
said thrust plate assembly comprises: a housing fixedly connectable
to a flywheel for joint rotation with the flywheel about an axis of
rotation; a pressure plate arranged in said housing so that said
pressure plate is fixed with respect to rotation relative to said
housing and axially displaceable relative to said housing; an
energy accumulator having one side supported at said housing and
another side supported at said pressure plate; and a wear
adjustment device arranged in a support path of said energy
accumulator between said energy accumulator and a component of one
of said housing and said pressure plate, wherein said wear
adjustment device includes at least one adjustment element
displaceable to compensate for wear and said wear adjustment device
is operatively arranged for effecting a wear compensation in
proportion to the occurring wear, wherein a ratio of said wear
compensation effected by said wear adjustment device to said
occurring wear differs from 1:1.
23. A friction clutch comprising a thrust plate assembly, wherein
said thrust plate assembly comprises: a housing fixedly connectable
to a flywheel for joint rotation with the flywheel about an axis of
rotation; a pressure plate arranged in said housing so that said
pressure plate is fixed with respect to rotation relative to said
housing and axially displaceable relative to said housing; an
energy accumulator having one side supported at said housing and
and another side supported at said pressure plate; a wear
adjustment device arranged in the support path of said energy
accumulator between said energy accumulator and a component of one
of said housing and said pressure plate, said wear adjustment
device having at least one adjustment element displaceable to
compensate for wear, wherein said at least one adjustment element
is pretensioned for movement in a wear adjustment movement
direction, wherein said at least one adjustment element comprises a
surface which moves along a counter-surface when said at least one
adjustment element moves in said wear adjustment movement
direction, wherein one of said surface and said counter-surface is
inclined in the wear adjustment movement direction; at least one
blocking member operatively arranged for blocking said at least one
adjustment element to prevent movement of said at least one
adjustment element in the wear adjustment movement direction; and
at least one play sensor arrangement for detecting occurring wear
and a blocking element displaceable with respect to another
component of said thrust plate assembly in response to occurring
wear, wherein said at least one play sensor arrangement comprises a
detection element arrangeable for interacting with said blocking
element for detecting wear, and said detection element being
displaceable to a position corresponding to the occurring wear by
the interaction with said blocking element, said at least one play
sensor arrangement further comprising a stopping element
operatively arranged for stopping said detection element in the
position corresponding to the occurring wear, and wherein said at
least one blocking member is arranged on said stopping element.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is directed to a thrust plate assembly
for a motor vehicle friction clutch with automatic wear
compensation including a housing that is fixedly connectable to a
flywheel for joint rotation with the flywheel about an axis of
rotation, a pressure plate arranged in the housing such that the
pressure plate is fixed with respect to rotation relative to the
housing and axially displaceable relative to the housing, an energy
accumulator having one side supported at the housing and another
side supported at the pressure plate, and a wear adjustment device
arranged in the support path of the energy accumulator between the
energy accumulator and a component of the housing and pressure
plate and including at least one adjustment element which is
displaceable to compensate for wear, the wear adjustment device
being operatively arranged for compensating for wear in proportion
to the occurring wear.
[0003] 2. Description of the Related Art
[0004] A prior art thrust plate assembly is disclosed in German
reference DE-A-29 20 932 having a wear adjustment device with an
adjustment ring with a plurality of surface regions arranged
successively in circumferential direction. These plural surface
regions are inclined relative to the circumferential direction and
contact corresponding counter-surfaces of a pressure plate which
are inclined relative to the circumferential direction. During a
rotation of this adjustment ring in circumferential direction,
i.e., in a wear adjustment movement direction, the surfaces and
counter-surfaces slide against one another so that the adjustment
ring is displaced axially in relation to the pressure plate and
compensates, e.g., for wear occurring in the region of friction
facings. The adjustment ring is pretensioned by an adjusting spring
for movement in the circumferential movement direction. In this
known thrust plate assembly, an area of a diaphragm spring acting
on the adjustment ring is swiveled during a disengaging or
releasing movement and the pressure plate follows this movement of
the diaphragm spring essentially completely. However, if wear which
is detectable by a play sensor of the thrust plate assembly has
occurred previous to the disengaging movement, the release path of
the pressure plate is limited so that at the end of the movement
travel or lift of the diaphragm spring, the pressure plate no
longer follows this lift and the wear adjustment device, i.e., the
adjustment ring, is consequently released for carrying out the
compensating movement mentioned above. The extent to which the
pressure plate no longer follows the lifting off movement of the
diaphragm spring corresponds precisely to the wear previously
detected by the play sensor. The precise amount of this release
path that is no longer traveled is compensated by the wear
adjustment device. Therefore, the adjustment ring initially
directly contacts the diaphragm spring again during an engagement
process to be carried out subsequently and finally the diaphragm
spring acts upon the subassembly formed of the pressure plate and
adjustment ring to the precise extent and manner as with a clutch
disk which does not exhibit any wear. Even when wear occurs, the
installation position of the diaphragm spring does not change over
the life of a thrust plate assembly of this type so that the
releasing force required remains essentially the same and the
clutch characteristic remains essentially unaltered.
SUMMARY OF THE INVENTION
[0005] An object of the present invention to provide a thrust plate
assembly which has an improved capacity for adapting to operating
conditions which change over the operating life of a clutch.
[0006] The object is met according to an embodiment of the present
invention by a thrust plate assembly for a friction clutch in a
motor vehicle with automatic wear compensation, comprising a
housing fixedly connectable to a flywheel for joint rotation with
the flywheel about an axis of rotation, a pressure plate arranged
in the housing such that the pressure plate is fixed with respect
to rotation relative to the housing and axially displaceable
relative to the housing, an energy accumulator such as a diaphragm
spring having one side supported at the housing and another side
supported at the pressure plate, and a wear adjustment device
arranged in the support path of the energy accumulator between the
energy accumulator and a component of the housing and pressure
plate. The wear adjustment device has at least one adjustment
element which is displaceable to compensate for wear and is
operatively arranged for effecting wear compensation in proportion
to the occurring wear.
[0007] In the thrust plate assembly according to the present
invention, the ratio of movement of the wear adjustment device to
the amount of wear differs from 1:1.
[0008] As was already noted, the axial expansion of the subassembly
formed of the pressure plate and adjustment ring when carrying out
wear compensation in the prior art is exactly the same as the
extent to which friction linings become thinner. However, it has
been determined that other characteristics of the thrust plate
assembly which change over its useful life are not accounted for by
this arrangement. It has been recognized, for example, that the
operating characteristic, i.e., force characteristic, of a spring
element such as an energy accumulator changes over the operating
life. This property of the spring element is taken into account by
the present invention in that a compensation process is not
implemented in a ratio of 1:1 to the actually occurring wear.
Rather, it is ensured by diverging from this ratio of 1:1 in a
defined manner that the installation position of the energy
accumulator changes in spite of the occurrence of wear and the
execution of a compensating movement compelled by the occurrence of
wear.
[0009] According to the present invention, when a spring force
decreases in a determined installation position due to fatigue,
wear compensation may be effected to a determined degree while
simultaneously bringing the energy accumulator into a position
which allows the spring to generate a higher force than in the
original installation position, i.e., in the new state. Therefore,
the defined selection of the ratio, which now no longer takes into
account the exact wear actually occurring, accounts for many
different variables which are known to change over the operating
life of a clutch. In this way, the operating characteristic of a
thrust plate assembly of this type and a clutch outfitted with this
thrust plate assembly may be maintained in an improved manner.
[0010] The thrust plate assembly according to the present invention
may, for example, comprise at least one adjustment element that is
movable in a wear adjustment movement direction corresponding to
occurring wear and that the movement in the wear adjustment
movement direction causes a displacement of at least one adjustment
element in a compensating movement direction different than the
wear adjustment movement direction, and that the extent of movement
in the compensating movement direction for wear and the wear itself
is in a ratio other than 1:1.
[0011] A desired ratio between the wear which occurs and is
detected and the compensation that is actually implemented is
achieved in that the at least one adjustment element moves in the
wear adjustment movement direction with a surface inclined in the
wear adjustment movement direction along a counter-surface.
Alternatively, the desired ratio may be achieved in that the at
least one adjustment element moves along a counter-surface inclined
in the wear adjustment movement direction. In both cases, the angle
of inclination of the surface or counter-surface is selected in
such a way that the extent of movement in the compensating movement
direction is in a ratio to wear other than 1:1.
[0012] To detect wear in operation, the thrust plate assembly
according to the invention may have at least one play sensor
arrangement with a detection element having a detection portion
arranged for interacting with a component or subassembly for
detecting wear. The component or subassembly with which the
detection portion is interactable is displaceable with respect to
another component when wear occurs. Therefore, when wear occurs,
the detection element is positioned corresponding to the wear
detected by the interaction with the component or subassembly.
[0013] To achieve the desired stopping of the movement of each
detection element, an embodiment of the present invention includes
a stopping element displaceable in a stopping movement direction by
a movement extent or distance corresponding to the wear to stop the
detection element when wear occurs. The stopping element has a
blocking member for cooperating with the at least one adjustment
element to limit the movement of the adjustment element in the wear
adjustment movement direction to an extent corresponding to the
wear.
[0014] The wear adjustment movement direction of the at least one
adjustment element is in the same direction as the movement of the
stopping element in the stopping movement direction so that the
cooperation between the stopping element and the at least one
adjustment element in the simplest possible manner.
[0015] For example, the stopping movement direction and the wear
adjustment movement direction may correspond essentially to a
circumferential movement direction. The blocking member then
preferably forms a stop acting substantially in the wear adjustment
movement direction. In this arrangement, the stop acts directly in
the direction in which the at least one adjustment element moves
under pretensioning to effect a compensating movement. In contrast
to the prior art in which the generated compensating movement,
i.e., the axial movement, is directly limited by a stop which acts
axially in a corresponding manner, the present invention limits a
movement which may, for example, be in the circumferential
direction which does not necessarily require an axial stop.
Therefore, the movement in the compensating movement direction,
i.e., the actual axial expansion of the wear adjustment device, may
be configured to be different than the wear that has occurred in
any desired manner. The movement in the compensating movement
direction is decoupled from a determined extent of axial movement
and the extent of axial movement is predetermined by this movement
in the wear adjustment movement direction.
[0016] The stopping element may, for example, be wedge-shaped with
an angle of the wedge-shaped stopping element differing from an
angle of inclination of the surface or counter-surface. Therefore,
a movement distance of the stopping element in its stopping
movement direction is equal to the movement distance of the at
least one adjustment element in the wear adjustment movement
direction. However, the axial expansion of the wear adjustment
device or of the subassembly formed of the pressure plate and the
at least one adjustment element which occurs is different from the
actual or detected wear because of the different angle of
inclination between the wedge-shaped stopping element and the
surface or counter-surface. Accordingly, the ratio differing from
1:1 is achieved.
[0017] In a further embodiment, one of the wedge angle of the
stopping movement direction and the angle of the
surface/counter-surface may be arranged so that it is not constant
in the wear adjustment direction. This allows characteristics of
the thrust plate assembly which do not change linearly over the
operating life of a thrust plate assembly of this kind to be taken
into account.
[0018] In particular, if the setting of a spring used as energy
accumulator is to be taken into account with the present invention,
the ratio is less than 1:1 and preferably in the range including
0.6 to 0.95.
[0019] As discussed above, the ratio may change as compensation of
wear increases, i.e., over the operating life of the thrust plate
assembly, to take into account influencing variables which do not
change linearly. For this purpose, the ratio preferably increases
as the compensation of wear increases. The increase of the ratio as
the compensation of wear increases allows the influence of "spring
setting", as it is called, to be accounted for in which springs,
e.g., diaphragm springs, which are used as energy accumulators
change their characteristic relatively dramatically in the initial
phase of their operating life and remain virtually unchanged or
change only slightly after this initial relatively sharp change in
characteristic.
[0020] According to another embodiment of the present invention,
the object is met by a thrust plate assembly for a motor vehicle
friction clutch with automatic wear compensation, comprising a
housing fixedly connectable to a flywheel for joint rotation
jointly with the flywheel about an axis of rotation, a pressure
plate which is arranged in the housing so that th e pressure plate
is fixed with respect to rotation relative to the housing and is
axially displaceable relative to the housing, an energy accumulator
such as a diaphragm spring having one side supported at the housing
and another side supported at the pressure plate, and a wear
adjustment device arranged in the support path of the energy
accumulator between the energy accumulator and a component of the
housing and pressure plate. The wear adjustment device has at least
one adjustment element displaceable to compensate for wear and is
pretensioned for movement in a wear adjustment movement direction.
When the wear adjustment device moves in the wear adjustment
movement direction, a surface of the at least one adjustment
element inclined in the wear adjustment movement direction moves
along a counter-surface. Furthermore, the at least one adjustment
element may be blocked by at least one blocking member to prevent
movement in the wear adjustment movement direction. The thrust
plate assembly further comprises at least one play sensor
arrangement for detecting wear, wherein the at least one play
sensor arrangement comprises a detection element which interacts
with or can be made to interact with a component or subassembly for
detecting wear. The component or subassembly is displaceable with
respect to another component of the thrust assembly when wear
occurs so that the detection element is brought into a position
corresponding to the wear by the interaction with the component or
subassembly.
[0021] This thrust plate assembly includes a stopping element for
stopping the detection element of the at least one play sensor
arrangement in its position corresponding to the wear. Furthermore,
the at least one blocking member is provided at the stopping
element.
[0022] According to this embodiment, a blocking of the movement of
the at least one detection element is not required to act in axial
direction as was the case in the prior art. Therefore, a desired
conversion of the amount of detected wear into the compensating
movement associated with the operating life may be effected.
[0023] For this purpose, the at least one blocking member may be
arranged to interact with the at least one adjustment element so as
to block essentially in the wear adjustment movement direction.
[0024] The counter-surface may be formed at the one component on
which the wear adjustment device is arranged. Also, the at least
one detection element may be arranged with a detection portion for
interacting with the component or subassembly. For example, the
component or subassembly that interacts with the detection element
may comprise the housing or the energy accumulator or any component
which moves relative to the pressure plate when wear occurs.
[0025] At least a portion of the detection element may be located
between the at least one adjustment element and the one component
on which the adjustment element is arranged. The at least one
adjustment element may, for example, comprise an adjustment ring
which is arranged substantially concentric to the axis of rotation.
Furthermore, the one component is the pressure plate and the
detection portion of the at least one detection element projects
through an intermediate space formed between the adjustment ring
and the pressure plate. Further, the stopping element is
displaceable in a stopping movement direction when wear occurs by a
movement amount corresponding to the wear to stop the detection
element in its position corresponding to wear. In this respect, it
is preferable for the wear adjustment movement direction of the at
least one adjustment element to be the same direction as the
stopping movement direction of the stopping element. The wear
adjustment movement direction and the stopping movement direction
is preferably a circumferential direction.
[0026] The present invention is further directed to a friction
clutch with a thrust plate assembly according to the present
invention.
[0027] Other objects and features of the present invention will
become apparent from the following detailed description considered
in conjunction with the accompanying drawings. It is to be
understood, however, that the drawings are designed solely for
purposes of illustration and not as a definition of the limits of
the invention, for which reference should be made to the appended
claims. It should be further understood that the drawings are not
necessarily drawn to scale and that, unless otherwise indicated,
they are merely intended to conceptually illustrate the structures
and procedures described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] In the drawings, wherein like reference characters denote
similar elements throughout the several views:
[0029] FIG. 1 is a partial axial sectional view of a thrust plate
assembly according to an embodiment of the present invention in
which the housing and energy accumulator are omitted;
[0030] FIG. 2 is a sectional view of the thrust plate assembly of
FIG. 1 along line II-II in FIG. 1;
[0031] FIG. 3 is a sectional view of the thrust plate assembly of
FIG. 1 along line III-III in FIG. 1;
[0032] FIG. 4 is a perspective view of a stopping element used in
the thrust plate assembly of FIG. 1;
[0033] FIG. 4A is a view of a further embodiment of the stopping
element of FIG. 4 having a non-linear wedge angle;
[0034] FIG. 5 is a perspective view of the thrust plate assembly
according to FIG. 1;
[0035] FIG. 6 is a force diagram of an energy accumulator formed as
a diaphragm spring or disk spring showing the dependency of the
spring force on the spring path;
[0036] FIG. 7 is a diagram corresponding to FIG. 6 which shows the
influence of aging on a spring force characteristic;
[0037] FIG. 8 is a perspective partial view of an alternative
embodiment of the thrust plate assembly according to the present
invention; and
[0038] FIG. 9 is a view of the thrust plate assembly shown in FIG.
8 from the radial outer side.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0039] FIGS. 1 to 5 show a thrust plate assembly 10 according to an
embodiment of the present invention. The thrust plate assembly 10
includes a housing 12 (shown schematically in FIG. 2) via which the
thrust plate assembly 10 is connectable to a flywheel (not shown)
which may comprise any type of flywheel such as, for example, a
dual mass flywheel. A pressure plate 14 is arranged in the housing
12 and is held at the housing 12 by tangential leaf springs (also
not shown) so that the pressure plate 14 is fixed with respect to
rotation relative to the housing 12 and axially movable relative to
the housing 12. Friction facings of a clutch disk, for example, may
then be clamped between the pressure plate 14 and the flywheel as
is known in the art. The thrust plate assembly 10 shown in FIG. 2
is a push-type thrust plate assembly with an energy accumulator 16
such as, for example, a diaphragm spring, having a radial outer
area supported at the pressure plate 14 via a wear adjustment
device 18 and a radial central area supported at the housing 12
via, for example, spacer pins (not shown). The radial inner area of
the energy accumulator 16 is actuatable by a clutch release
mechanism, so that it is pushed into the housing 12 for
implementing a release process to at least partially cancel the
action of the energy accumulator upon the pressure plate 14.
[0040] In the embodiment of FIGS. 1-5, the wear adjustment device
18 comprises an adjustment ring 20 which is substantially
concentric to an axis of rotation, not shown. The adjustment ring
20 has a plurality of inclined surface regions 22 facing the
pressure plate 14 which are arranged successively in
circumferential direction and inclined relative to the
circumferential direction (see FIG. 5). These inclined surface
regions 22 rest on counter-inclined surface regions 24 of the
pressure plate 14 which are inclined in circumferential direction
in a corresponding manner. When the adjustment ring 22 moves in
circumferential direction with respect to the pressure plate 14 as
will be described in the following, the inclined surface regions 22
slide along the counter-inclined surface regions 24 so that the
adjustment ring 20 is simultaneously displaced in axial direction
during the circumferential movement by the surface regions 22, 24
which slide against one another and which are inclined with respect
to the circumferential direction. As a result of this displacement
in axial direction, a portion 26 of the adjustment ring 20 acted
upon by the diaphragm spring 16 is displaced axially with respect
to the pressure plate 14.
[0041] A detection element 28 is arranged as play sensor at the
pressure plate 14. The detection element 28 is located radially
inside the adjustment ring 20 and extends approximately in
circumferential direction proceeding from an end portion of the
adjustment ring 20 that is fixed to the pressure plate 14. The
detection element 28 may be produced from spring steel such as, for
example, a leaf spring. The detection element 28 has a detection
portion 32 that projects radially outward through a through-opening
34 formed between the adjustment ring 20 and the pressure plate 14.
In this area, the detection portion 32 overlaps in circumferential
direction and in radial direction with a blocking element 37 which
is shown only schematically in the drawings and which may, for
example, be fastened to the housing 12 or constructed as in
integral part therewith.
[0042] Further, the thrust plate assembly 10 includes a stopping
element 36 associated with the detection element 28. The stopping
element 36 extends essentially in circumferential direction and is
located at the inner side of the adjustment ring 20 between the
adjustment ring 20 and the detection element 28. The stopping
element 36 is wedge-shaped and extends in an intermediate space 35
formed between the detection portion 32 and the pressure plate
14.
[0043] The thrust plate assembly 10 further comprises an adjustment
spring 38 associated with the adjustment ring 20. A first end area
40 of the adjustment spring 38 is attached to the adjustment ring
20 and a second end area, not shown, is fastened to the pressure
plate 14. The adjustment spring 38 pretensions or biases the
adjustment ring 20 toward movement in a wear adjustment movement
direction, i.e., a circumferential movement direction. It is noted
that guide projections or guide elements are provided with the
thrust plate assembly, respectively, to ensure that the adjustment
spring 38 and the adjustment ring 20 are held in their installation
position surrounding the axis of rotation. Further, a pretensioning
spring 42 is arranged to ensure that the stopping element 36 is
pulled, accompanied by pretensioning, into the intermediate space
35 formed between the detection portion 32 and the pressure plate
14. The pretensioning spring 42 includes one side which acts on the
adjustment ring 20 and another side acting on a locating projection
44 of the stopping element 36. The other circumferential end area
of the stopping element 36 has a blocking projection 46 which
engages in a corresponding circumferential recess 48 of the
adjustment ring 20. The circumferential recess 48 has a larger
circumferential extension than the blocking projection 46, thereby
allowing relative circumferential movement of the stopping element
36 and the adjustment ring 20 to an extent limited by the recess
48.
[0044] The following describes the function and operation of the
thrust plate assembly described above and a friction clutch
outfitted with the thrust plate assembly during the occurrence of
wear.
[0045] It is first assumed that in a state without wear the energy
accumulator 16 acts on the wear adjustment device 18 and,
therefore, on the pressure plate 14 and urges the pressure plate 14
toward the flywheel. During a release process, the radial outside
of the energy accumulator 16 releases the wear adjustment device
18. The pressure plate 14 follows the releasing movement of the
energy accumulator 16 via the pretensioning force provided by the
tangential leaf springs holding the pressure plate 14 at the
housing 12. However, a circumferential end face 50 of the blocking
projection 46 of the stopping element 36 abuts an oppositely
located circumferential surface of the recess 48 of the adjustment
ring 20. Therefore, circumferential movement of the adjustment ring
20 which is pretensioned by the adjustment spring 38 is prevented.
The stopping element 36 is also blocked against circumferential
movement against the pretensioning of the pretensioning spring 42
and the pretensioning by the adjustment spring 38, which
pretensioning is transferred to the stopping element 36 via the
adjustment ring 20, in that the stopping element 36 abuts against
the detection portion 32 of the detection element 28. When the
clutch is engaged subsequently, the wear adjustment device 18 is
acted upon again by the diaphragm spring 16, so that the adjustment
ring 20 is clamped in any case between the energy accumulator 16
and the counter-inclined surface regions 24 of the pressure plate
14.
[0046] When wear occurs, for example, during a clutch engagement
process, the friction facings of the clutch disk become thinner and
the pressure plate 14 moves slightly closer to the flywheel. If the
wear is so extensive that the detection portion 32 strikes against
the blocking element 37, which will not move when wear occurs, at
least the detection portion 32 of the detection element 28 is
prevented from further following the axial movement of the pressure
plate 14. Consequently, the axial intermediate space 35 between the
pressure plate 14 and the detection portion 32 of the detection
element 28 becomes larger. The stopping element 36 which is
pretensioned in circumferential direction directly enters this
enlarged intermediate space with its stopping surface 52. This
stopping surface 52 is inclined at a predetermined angle with
respect to a base surface or base side 54 of the stopping element
36 supported at the pressure plate 14. The inclination of the
stopping surface achieves the wedge shape of the stopping element
36 mentioned above. Accordingly, as a result of the wedge shape,
the stopping element 36 moves in a stopping movement direction,
i.e., the circumferential direction, until the entire enlarged
intermediate space 35 between the pressure plate 14 and the
detection portion 32 of the detection element 28 is again filled.
Accordingly, the stopping element 36--as predetermined by the wedge
angle of the stopping element 36--moves in the stopping movement
direction to an extent corresponding to the occurring wear, i.e.,
corresponding to the axial displacement of the detection portion 32
with respect to the pressure plate 14.
[0047] The movement of the stopping element 36 to fill the space 35
causes the blocking projection 46 to move in circumferential
direction so that the blocking surface 50 moves away from the
oppositely located surface of the recess 48. When the blocking
surface 50 moves, the adjustment ring 20 is not blocked by the
stopping element 36 against movement in the wear adjustment
movement direction, i.e., the circumferential movement direction.
Because the clutch and thrust plate assembly is still in the
engaged state, the adjustment ring 20 is acted upon by the energy
accumulator 16 and is accordingly prevented from rotating.
[0048] However, as was already described, during a subsequent
release process, the diaphragm spring 16 ceases at least partially
to act upon the wear adjustment device 18 and the contact pressing
force acting between the adjustment ring 20 and the diaphragm
spring 16 is essentially predetermined by the tangential leaf
springs. The tangential leaf springs exert a force so slight that
the adjustment ring 20 is now movable in the circumferential
direction under pretensioning by the adjustment spring 38 until the
surface of the recess 48 again strikes the blocking face 50 of the
stopping element 36. As a result, the adjustment ring 20 moves in
circumferential direction by the same amount as the stopping
element 36 has moved to fill the intermediate space caused by the
wear. Therefore, the adjustment ring 20 has likewise moved in its
wear adjustment movement direction by an amount corresponding to
the wear that has occurred.
[0049] During this movement in the wear adjustment movement
direction, the adjustment ring 20 slides by its inclined surface
regions 22 along the counter-inclined surface regions 24 and is
accordingly displaced in axial direction, i.e., the compensating
movement direction, with respect to the pressure plate 14. This
displacement or movement in the compensating movement direction is
also in a determined ratio to the occurring wear. That is, the
ratio by which the movement in the wear adjustment movement
direction, is converted into a movement in axial direction, i.e.,
in the compensating movement direction, is determined by the angle
of inclination of the inclined surface regions 22 and
counter-inclined surface regions 24. A flatter angle of inclination
of these surface regions 22 and 24 produces a smaller movement in
the axial direction for a given circumferential movement than a
steep angle of inclination. Therefore, adjusting the angle of
inclination of the inclined surface regions 22 or counter-inclined
surface regions 24 allows a determination of the extent to which a
circumferential movement of the stopping element 36, and therefore
of the adjustment ring 20, is converted into an axial movement and
accordingly into a compensating movement. However, the extent of
the circumferential movement may again be set in a determined ratio
to the occurring wear by predetermining the wedge angle of the
stopping element 36. To obtain a compensation ratio other than 1,
it must accordingly be ensured that the circumferential movement of
the adjustment ring 20, which measures the same as the
circumferential movement of the stopping element 36, does not
produce an axial movement of the adjustment ring 20 which measures
the same as the axial relative movement of the detection portion 32
with respect to the pressure plate 14 which occurred previously.
This can be achieved, for example, by arranging the wedge angle of
the stopping element 36, i.e., the angle between the two surfaces
52 and 54, so that it is different from the angle of inclination of
the surface regions 22 or 24 with reference to a circumferential
line. To achieve undercompensation of wear, the angle of
inclination of the surface regions 22 and 24 must be flatter than
the wedge angle of the stopping element 36. To obtain
overcompensation, the angle of inclination of the surface regions
22, 23 must be greater than that of the stopping element 36.
[0050] This principle according to the present invention, whereby
the extent of wear compensation is adjusted by corresponding
constructional design and does not depend on the occurring wear in
a 1:1 ratio, is enabled by directly limiting the movement of the
wear adjustment device 18 in the wear adjustment movement direction
and not by an axial stop when the wear adjustment device 18 has
also axially moved to a determined extent. In other words, the
stopping which is achieved by the blocking projection 46 acts in
the circumferential movement direction, i.e., in the wear
adjustment movement direction, and not directly in the axial
direction, i.e., the compensating movement direction, as was the
case in the prior art.
[0051] With an arrangement of this kind, as was described in the
beginning, a characteristic of the thrust plate assembly that
changes over time may be taken into account. This is described with
reference to the diagrams of FIGS. 6 and 7. FIG. 6 shows a force
curve over the spring path or spring travel of a diaphragm spring
used as energy accumulator. The installation position occupied by a
diaphragm spring of this type when no wear has occurred, i.e., when
it is new, is designated by EL. The installation position occupied
by a diaphragm spring of this kind after wear has occurred is
designated by EL'. It will be seen that the change in installation
position has caused the force to approach the force maximum, for
example, in the clutch engagement position. Wear compensation is
peformed for purposes of compensation as was described in the
beginning, so that the installation position represented in the
diagram in FIG. 6 is held constant by the spring path
parameter.
[0052] However, the present invention also allows variables other
than occurring wear to be taken into account such as, for example,
the effect of so-called spring setting. The term "spring setting"
relates to the changing of a spring constant of a diaphragm spring
or disk spring over their operating life. The setting is more
dramatic in the initial period of operating life than at the end
and is represented in the graph in FIG. 7 by the transition from
curve K for the new state to curve K". Basically, it will be seen
that the force characteristic, while remaining essentially intact
qualitatively, shifts to lower forces, i.e., a lower force is
associated with a corresponding installation position of a spring
of this type. If it is taken into account, as shown in FIG. 6 and
as described above, only that wear occurs in the operation of a
clutch of this kind and if this wear is compensated in a ratio of
1:1 as is the case in the prior art, the result would be a steady
decrease in spring force in the clutch due to the decrease in
spring force, with installation position EL maintained constant, as
a result of overcompensation. However, when it is ensured by the
mechanism described in the preceding that the wear which actually
occurs is not compensated in its entirety but only in a ratio of
less than 1, a transition takes place to an installation position
EL" which, although it is closer to the force maximum in the spring
force curve for the used state, essentially corresponds to the new
state of the clutch because of the drop in the curve. That is, the
installation position changes to account for the changing spring
characteristic so that the force generated in the clutch is
maintained at a constant value. When a "setting" of an energy
accumulator 16 comprising a diaphragm spring is to be accounted
for, the ration is preferably whtin the range including
0.6-0.95.
[0053] Accordingly, the thrust plate assembly according to the
present invention allows adaptation to very different operating
parameters which change over the operating life of the thrust plate
assembly. Furthermore, non-linearly changing variables may also be
taken into account, for example, by a suitable construction of the
stopping element 36. For example, when more undercompensation is
required at the start of the operating life than toward the end of
operating life, the wedge angle of the stopping element 36 may be
arranged so that it is not constant, but rather has a greater wedge
angle in an area of the stopping element 36 that cooperates with
the detection portion 32 of the detection element 28 at the start
of operating life than in an area of the stopping element 36 that
cooperates with the detection portion 32 at the end of operating
life. That is, the same extent of wear at the start of the period
of operating life will lead to a smaller circumferential movement
of the stopping element 36 and to a correspondingly smaller
movement of the adjustment ring 20 in the compensation movement
direction than at the end of the useful operating period. An
exaggerated example of a non-linear or not constant wedge angle is
shown in FIG. 4A. Appropriate variations of the stopping element 36
may be made to achieve any desired characteristics. The same result
may also be achieved by arranging the inclined surface regions 22
or the counter-inclined surface regions 24 so that they do not have
a constant angle of inclination relative to the circumferential
direction and can then move along a supporting portion of the other
respective subassembly.
[0054] The thrust plate assembly 10 according to the present
invention has the further advantage that the stopping element 36
cooperates with the adjustment ring 20 so that the adjustment ring
20 blocked against movement in a wear adjustment movement direction
when it is not acted upon by the energy accumulator 16. The
stopping element 36 simultaneously forms a transport or assembly
safety mechanism for the adjustment ring 20, so that no unwanted
wear compensation occurs before assembling the thrust plate
assembly, for example, with a flywheel, or before a subassembly
formed of a pressure plate 14 and adjustment ring 20 is joined
together with the housing 12 and energy accumulator 16. The
location of the detection portion 32 of the detection element 28
partially axially between the adjustment ring 20 and the pressure
plate 14 in the embodiment shown in FIGS. 1 to 5 simplifies
construction. This embodiment also obviates the need to provide a
relatively large circumferential cutout in the adjustment ring 20
in the region associated with the energy accumulator 16 for the
detection portion 32 which is guided past the adjustment ring 20
from the radial inside to the radial outside, the function of this
circumferential cutout being to allow the adjustment ring 20 to
rotate freely with respect to the detection portion 32 over the
entire operating life, that is, over the entire circumferential
movement of the adjustment ring 20. Accordingly, the energy
accumulator 16 acts upon the wear adjustment device 18 in a more
uniform manner. The location of the detection portion 32 axially
between the adjustment ring 20 and the pressure plate 14 is allowed
because the detection element 28 does not have to act directly on
the adjustment ring 20 or the wear adjustment device 18 to limit
its adjusting movement with an axial stop. Rather, a limiting of
the circumferential movement is provided for the adjustment ring 20
by the stopping element 36.
[0055] Construction the thrust plate assembly 10 in FIGS. 1-5 is
relatively simple because only an adjustment ring 20 is used in
this embodiment. However, the principle of operation according to
the present invention is also applicable in principle when using
other adjustment elements, for example, wedge-shaped and/or
radially moving adjustment elements. Furthermore, an embodiment
form of the wear adjustment device 18 with two adjustment rings is
also possible. An embodiment of the thrust plate assembly 10 having
two adjustment rings is shown in FIGS. 8 and 9. In this embodiment,
the wear adjustment device 18 has two adjustment rings 20 and 20'
which contact one another by respective inclined surface regions 22
and counter-inclined surface regions 24. The first end portion 40
of the adjustment spring 38 is attached the adjustment ring 20' and
the second end portion of the adjustment spring is fastened, for
example, to the adjustment ring 20 or to the pressure plate 14.
[0056] In FIGS. 8 and 9, the detection portion 32 penetrates a
circumferential recess 68 of the adjustment ring 20. The detection
element 28 is fastened to the pressure plate 14 to ensure that the
adjustment ring 20 is not movable in circumferential direction.
Further, FIG. 9 shows that the detection portion 32 is not
supported axially at the adjustment ring, i.e., it does not
obstruct or block the axial movement of the adjustment ring 20 in
the compensation movement direction.
[0057] The blocking projection 46 of the stopping element 36
engages the circumferential recess 48 of the adjustment ring 20' as
in the previous embodiment of FIGS. 1-5. When wear occurs and
application of the energy accumulator 16 is released, the wear
adjustment device 18 functions such that the adjustment ring 20'
moves in a circumferential direction until it strikes the blocking
surface 50 of the blocking projection 46. The adjustment ring 20
which is held against rotation is displaced axially while the
adjustment ring 20' moves in the circumferential direction for
performing compensation by the inclined surfaces 22, 24 which slide
against one another. The extent of the axial movement of the
adjustment ring 20 is dependent on the ratio of the inclination of
the inclined surfaces 22, 24 to the wedge angle of the stopping
element 36. Thus, in this embodiment form the function of wear
adjustment movement in the wear adjustment movement direction is
performed by adjustment ring 20' and compensation movement in the
compensation movement direction is performed by adjustment ring
20.
[0058] It is noted that in the examples described above the
detection of wear is carried out with reference to the housing 12
when the play sensor, i.e., the detection element 28, is provided
at the pressure plate 14. Of course, the wear could also be
detected with reference to the energy accumulator 16, namely, in
that the detection portion 32 acts at the energy accumulator 16.
The detection portion 32 may pass through corresponding openings in
the energy accumulator and contact the energy accumulator from the
rear. The energy accumulator 16 also moves, that is, when wear
occurs, relative to the pressure plate 14 and accordingly enables
detection of wear.
[0059] Thus, while there have shown and described and pointed out
fundamental novel features of the invention as applied to a
preferred embodiment thereof, it will be understood that various
omissions and substitutions and changes in the form and details of
the devices illustrated, and in their operation, may be made by
those skilled in the art without departing from the spirit of the
invention. For example, it is expressly intended that all
combinations of those elements which perform substantially the same
function in substantially the same way to achieve the same results
are within the scope of the invention. Moreover, it should be
recognized that structures and/or elements shown and/or described
in connection with any disclosed form or embodiment of the
invention may be incorporated in any other disclosed or described
or suggested form or embodiment as a general matter of design
choice. It is the intention, therefore, to be limited only as
indicated by the scope of the claims appended hereto.
* * * * *