U.S. patent application number 09/768677 was filed with the patent office on 2001-06-21 for hydraulic clutch release mechanism.
Invention is credited to Meyer, Gerhard, Winkelmann, Ludwig.
Application Number | 20010004038 09/768677 |
Document ID | / |
Family ID | 26047672 |
Filed Date | 2001-06-21 |
United States Patent
Application |
20010004038 |
Kind Code |
A1 |
Winkelmann, Ludwig ; et
al. |
June 21, 2001 |
Hydraulic clutch release mechanism
Abstract
A hydraulic clutch release mechanism, particularly for use in
the power train of a motor vehicle, employs a circular piston which
is reciprocable in a plenum chamber between a cylindrical housing
and a guide centrally located within the housing. One end portion
of the piston is form-lockingly connected with a plastic seal at
the plenum chamber. Such form-locking connection is provided
adjacent one of two lips forming part of the seal. The one lip
engages the external surface of the guide and the other lip engages
the internal surface of the housing and is adjacent another
form-locking connection established between the seal and an annular
plastic or metallic retainer which is affixed to the piston with
limited axial play. The other end portion of the piston is
operatively connected with a clutch, e.g., by way of a release
bearing.
Inventors: |
Winkelmann, Ludwig;
(Erlangen, DE) ; Meyer, Gerhard; (Lehrberg,
DE) |
Correspondence
Address: |
DARBY & DARBY P.C.
805 Third Avenue
New York
NY
10022
US
|
Family ID: |
26047672 |
Appl. No.: |
09/768677 |
Filed: |
January 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09768677 |
Jan 24, 2001 |
|
|
|
PCT/EP99/04113 |
Jun 15, 1999 |
|
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Current U.S.
Class: |
192/85.51 ;
92/107 |
Current CPC
Class: |
F16D 2300/08 20130101;
F16D 25/083 20130101 |
Class at
Publication: |
192/85.0CA ;
192/91.00A; 92/107 |
International
Class: |
F16D 025/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 1998 |
DE |
198 33 342.0 |
Aug 7, 1998 |
DE |
198 35 707.9 |
Claims
What is claimed is:
1. A hydraulic clutch release mechanism, comprising: a
cylinder-piston unit including a cylindrical housing having an
internal surface, a guide having an external surface spacedly
surrounded by and defining with said internal surface a plenum
chamber, and a piston having first and second end portions and
being reciprocable in said chamber; a seal disposed in said chamber
at one end portion of said piston and including a first section
contacting said internal surface, a second section contacting said
external surface and a third section form-lockingly engaging said
one end portion of said piston; and an annular retainer affixed to
said piston and including a portion form-lockingly engaging said
seal.
2. The mechanism of claim 1, wherein said first and second sections
of said seal include lips.
3. The mechanism of claim 1, further comprising means for
operatively connecting the other end portion of said piston with a
friction clutch in a motor vehicle.
4. The mechanism of claim 1, wherein said third section of said
seal includes a first part which form-lockingly engages said one
end portion of said piston and a second part which form-lockingly
engages said portion of said retainer.
5. The mechanism of claim 4, wherein one of said retainer and said
second part of said third section of said seal has an annular
groove extending at least substantially radially of said housing
and the other of said retainer and said second part of said third
section of said seal has an annular bead in said groove.
6. The mechanism of claim 5, wherein said annular bead is provided
on said retainer.
7. The mechanism of claim 4, wherein said one end portion of said
piston has first and second surfaces making an angle which at least
approximates 90.degree., said first part of said third section of
said seal having third and fourth surfaces respectively abutting
said first and second surfaces.
8. The mechanism of claim 4, wherein one of said one end portion of
said piston and said first part of the third section of said seal
includes an undercut recess and the other of said one end portion
of said piston and said first part of the third section of said
seal at least substantially fills said undercut recess.
9. The mechanism of claim 8, wherein said recess is provided in
said one end portion of said piston.
10. The mechanism of claim 1, wherein one of said retainer and said
piston has at least one projection received in a recess of the
other of said retainer and said piston.
11. The mechanism of claim 10, wherein said at least one projection
is received in said recess by snap action.
12. The mechanism of claim 10, wherein said at least one projection
is received in said recess with at least some play in the axial
direction of said housing.
13. The mechanism of claim 1, wherein said one end portion of said
piston includes a stepped cylinder.
14. The mechanism of claim 1, wherein one of said one end portion
of said piston and said portion of said retainer includes an
undercut annular groove and said seal has a projection
complementary to and received in said groove.
15. The mechanism of claim 1, wherein said retainer is affixed to
said piston by one of the undertakings including crimping, beading
and burnishing.
16. The mechanism of claim 1, wherein said retainer is bonded to
said piston.
17. The mechanism of claim 1, wherein said retainer contains
steel.
18. The mechanism of claim 1, wherein said retainer is a deep drawn
article.
19. The mechanism of claim 1, wherein said retainer is a converted
blank which has undergone a material removing treatment.
20. The mechanism of claim 1, wherein said retainer is an
extrusion.
21. The mechanism of claim 1, wherein said retainer contains
aluminum.
22. The mechanism of claim 1, wherein said retainer contains a
plastic material.
23. The mechanism of claim 1, wherein said retainer has at least
one opening and further comprising means for coupling said retainer
to said piston including a portion received in said at least one
opening.
24. The mechanism of claim 23, wherein said portion of said
coupling means extends substantially radially of said housing.
25. The mechanism of claim 23, wherein said piston has a recess for
said portion of said coupling means.
26. The mechanism of claim 25, wherein said portion of said
coupling means extends into said recess with at least some freedom
of movement in the axial direction of said housing.
27. The mechanism of claim 26, wherein said portion of said
coupling means is resilient and is received in said at least one
opening and said recess in a prestressed condition as seen radially
of said piston.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to fluid-operated clutch release
mechanisms, and more particularly to improvements in hydraulic
mechanisms which can be utilized with advantage to release
clutches, such as friction clutches, in the power trains of motor
vehicles. Still more particularly, the invention relates to
improvements in hydraulic clutch release mechanisms of the type
wherein a cylinder-piston unit employs a cylindrical housing and an
internal guide which defines with the housing an annular plenum
chamber for a reciprocable piston adapted to actuate the clutch by
way of a release bearing or the like.
[0002] A hydraulic clutch release mechanism which is disclosed in
published German patent application Serial No. 196 35 101 A1
employs a piston which is arranged to change the condition of a
diaphragm spring in a friction clutch of the character often
employed in the power trains of motor vehicles. The piston of the
release mechanism carries a lip seal which is secured thereto by a
connector. The latter is anchored in or recessed into the lip seal,
and an axially extending leg of such connector is recessed into the
peripheral surface of the piston.
[0003] A drawback of the just described conventional clutch release
mechanism is that the seal is apt to jam and/or to be tilted in the
plenum chamber; this exerts an adverse influence upon the guidance
of the piston and can affect the ability of the piston to actuate
the clutch.
OBJECTS OF THE INVENTION
[0004] An object of the present invention is to provide a hydraulic
clutch release mechanism which is more reliable and lasts longer
than heretofore known release mechanisms including that disclosed
in the aforementioned German patent application Serial No. 196 35
101 A1.
[0005] Another object of the invention is to provide a novel and
improved piston-seal combination for use in a hydraulic clutch
release mechanism.
[0006] A further object of the invention is to provide a novel and
improved arrangement for coupling the seal to the piston in a
hydraulic clutch release mechanism.
[0007] An additional object of the invention is to provide a clutch
release mechanism wherein the seal is not likely to leave its
desirable optimum position relative to the piston.
[0008] Still another object of the invention is to provide a novel
and improved method of securing the seal to the piston in the
plenum chamber of a hydraulic clutch release mechanism.
[0009] A further object of the invention is to provide a novel and
improved piston for use in the above outlined hydraulic clutch
release mechanism.
[0010] Another object of the invention is to provide a novel and
improved seal for use in a clutch release mechanism of the above
outlined character.
[0011] An additional object of the invention is to provide a novel
and improved retainer which couples the seal to the piston in a
hydraulic clutch release mechanism.
[0012] Still another object of the invention is to provide a power
train which can be utilized in a motor vehicle and employs the
above outlined improved clutch release mechanism.
SUMMARY OF THE INVENTION
[0013] The instant invention is embodied in a clutch release
mechanism which comprises a cylinder-piston unit including a
cylindrical housing having an internal surface, a centrally located
guide having an external surface spacedly surrounded by the
internal surface of the housing and defining with such internal
surface a plenum chamber, and a piston which has spaced-apart first
and second end portions and is reciprocable in the plenum chamber.
The improved clutch release mechanism further comprises a seal
which is disposed in the chamber at one end portion of the piston
and includes a first section (such as an annular lip) contacting
the internal surface of the housing, a second section (such as an
annular lip) which contacts the external surface of the guide, and
a third section which form-lockingly engages the one end portion of
the aforementioned piston, and an annular retainer which is affixed
to the piston and includes a portion form-lockingly engaging the
seal.
[0014] The improved release mechanism can further comprise means
(such as a bearing) for operatively connecting the other end
portion of the piston with a friction clutch in a motor vehicle,
e.g., with the prongs of a diaphragm spring.
[0015] The third section of the seal can include a first part which
form-lockingly engages the one end portion of the piston and a
second part which form-lockingly engages the aforementioned portion
of the retainer. The retainer or the second part of the third
section of the seal can be provided with an annular groove which
extends substantially radially of the housing, and the other of
these components is then provided with an annular bead which
extends into and preferably fills the groove. It is presently
preferred to provide the bead on the retainer.
[0016] The one end portion of the piston can be configurated in
such a way that it includes mutually inclined first and second
surfaces which preferably make an angle at least approximating
90.degree.; the first part of the third section of the seal is then
provided or can be provided with mutually inclined third and fourth
surfaces which respectively abut (such as lie flush against) the
first and second surfaces.
[0017] The one end portion of the piston or the first part of the
third section of the seal can be provided with an undercut recess,
and the other of these components is then provided with a portion
which at least substantially fills the undercut recess. For
example, the recess can be provided in the one end portion of the
piston.
[0018] Furthermore, the retainer or the piston can be provided with
at least one projection which is received in a recess of the other
of these components. The at least one projection can be received in
the recess by snap action. Furthermore, the at least one projection
can be received in the recess with at least some play as seen in
the axial direction of the housing.
[0019] The one end portion of the piston can constitute a stepped
cylinder having a first annular portion slidable along the guide
and a second annular portion which is axially and radially offset
relative to the first portion and is slidable along the
housing.
[0020] Furthermore, the one end portion of the piston or the
aforementioned portion of the retainer can be provided with an
undercut annular groove for a projection which is complementary to
the undercut annular groove and is provided on the seal.
[0021] The retainer can be affixed to the piston in any one of a
plurality of different ways, e.g., by crimping, beading or
burnishing. It is also possible to bond the retainer to the piston
(e.g., by welding, soldering, brazing and/or by resorting to a
suitable adhesive substance).
[0022] The retainer can be made of or can contain steel, aluminum
or another suitable metallic material. It is also possible to make
the retainer, at least in part, of a suitable plastic material.
Furthermore, the retainer can constitute an extrusion, it can
constitute a deep drawn article, or it can constitute a converted
blank which has undergone a material removing treatment, e.g., in a
lathe.
[0023] The retainer can be secured to the piston in a number of
suitable ways. A presently preferred mode includes the utilization
of a coupling which is carried by the piston and at least a portion
of which extends into an opening of the retainer. Such portion of
the coupling extends or can extend substantially radially of the
housing, and the piston can be provided with a recess for the
aforementioned portion of the coupling; this portion can extend
into the recess of the piston with at least some freedom of
movement as seen in the axial direction of the housing.
Furthermore, the aforementioned portion of the coupling can be
made, at least in part, of a resilient material and can be mounted
in the at least one opening of the retainer and in the recess of
the piston in prestressed condition (as seen radially of the
piston).
[0024] The novel features which are considered as characteristic of
the invention are set forth in particular in the appended claims.
The improved clutch release mechanism itself, however, both as to
its construction and the modes of assembling, installing and
utilizing the same, together with numerous additional important and
advantageous features and attributes thereof, will be best
understood upon perusal of the following detailed description of
certain presently preferred specific embodiments with reference to
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a fragmentary axial sectional view of a hydraulic
clutch release mechanism which embodies one form of the present
invention and employs a plastic piston, a plastic seal and a
metallic retainer;
[0026] FIG. 2 is an enlarged view of a detail in the structure
shown in FIG. 1;
[0027] FIG. 3 is a fragmentary axial sectional view of a second
hydraulic clutch release mechanism wherein the piston is
operatively connected with a clutch release bearing in a manner
different from that shown in FIG. 1;
[0028] FIG. 4a is a fragmentary axial sectional view of a piston
and of a retainer which is connected to the piston in a manner
different from those shown in FIGS. 1-2 and 3;
[0029] FIG. 4b illustrates the retainer of FIG. 4a and a modified
piston in a view corresponding to that of FIG. 4a;
[0030] FIG. 5a is a fragmentary axial sectional view of a clutch
release mechanism which employs a plastic retainer; and
[0031] FIG. 5b is a similar fragmentary axial sectional view but
showing a different piston, a different seal and a different
retainer.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0032] FIG. 1 shows certain relevant details of a hydraulic clutch
release mechanism which includes a cylinder-piston unit 1 having a
cylindrical housing 2 and a guide 3 which is coaxial with and is
surrounded by the housing. The internal surface 7 of the housing 2
and the external surface 8 of the guide 3 define an annular plenum
chamber 4 for an annular piston 5 which is coaxial with and is
reciprocable along the surfaces 7, 8 of the parts 2, 3. The piston
5 includes an annular end portion 12 which is movable away from and
toward the lower end of the chamber 4 (as viewed in FIG. 1). The
housing 2 has a suitably configurated channel 26 which can receive
a hydraulic fluid (such as oil or a transmission fluid) serving to
move the piston 5 axially of the housing 2 and guide 3.
[0033] The end portion 12 of the piston 5 carries an annular seal 6
having a first annular section or lip 9 sealingly engaging and
slidable along the internal surface 7 of the housing 2, and a
second annular section or lip 10 which sealingly engages the
external surface 8 of the guide 3. The seal 6 further includes a
third or median section 13 which is form-lockingly connected to the
end portion 12 of the piston 5 and which is also form-lockingly
connected with a portion 16 (see FIG. 2) of a cylindrical retaining
member 11 (hereinafter called retainer for short).
[0034] That end portion of the piston 5 which is remote from the
aforementioned end portion 12 is connected with a fastener 25 which
is further connected with a clutch release bearing or disengaging
bearing 27 serving to operatively connect the piston with the
prongs of a diaphragm spring forming part of a friction clutch.
Reference may be had, for example, to the friction clutch which is
described and shown in commonly owned U.S. Pat. No. 5,135,092
granted Aug. 4, 1992 to Johann Jackel for "APPARATUS FOR
TRANSMITTING TORQUE". A helical coil spring 28 is provided to bias
the release bearing 27 in the axial direction of the housing 2,
guide 3 and piston 5.
[0035] The fastener 25 comprises a resilient projection 22 which is
yieldably received in a recess or socket 20 of the second end
portion of the piston 5, e.g., by snap action. FIG. 1 shows the
piston 5 in that end position in which a radial shoulder 32 of the
piston abuts a cylindrical protuberance 33 (e.g., the respective
end portion) of the housing 2.
[0036] FIG. 1 further shows that the third section 13 of the seal 6
is form-lockingly connected with the end portion 12 of the piston 5
in a first manner and that this section 13 is form-lockingly
connected with the portion 14 of the retainer 11 in a different
second manner. Thus, and in contrast with the teachings of prior
art, the section 13 of the seal 6 is form-lockingly connected not
only with the end portion 12 of the piston 5 (adjacent the second
section or lip 10) but also with the adjacent portion 14 of the
retainer 11. This is tantamount to the establishment of two
form-locking connections between the piston 5 and the seal 6 (one
adjacent the lip 9 and the other adjacent the lip 10) because the
retainer 11 is affixed to the piston. The establishment of such
twin form-locking connections (one of which operates directly
between the end portion 12 of the piston and the seal 6 adjacent
the lip 10 and the other of which operates between the end portion
12 of the piston and the section 13 adjacent the lip 9 by way of
the retainer 11) contributes significantly to a desirable fixing of
the seal 6 to the piston 5 as well as to retention of the seal in
an optimum position or orientation relative to the surfaces 7 and
8.
[0037] FIG. 2 shows (drawn to a larger scale) the details of the
form-locking connections between the third section 13 of the seal 6
on the one hand, and the end portion 12 of the piston 5 and the
respective portion 14 of the retainer 11 on the other hand. This
Figure further shows the details of one presently preferred manner
in which the retainer 11 is fastened to the piston 5 adjacent the
latter's end portion 12. The portion 14 of the retainer 11 is
provided with an annular bead 16 which is form-lockingly received
in and preferably fills a complementary groove or socket 17 in the
third section 13 of the seal 6. The form-locking connection between
the end portion 12 of the piston 5 and the section 13 of the seal 6
is established by two surfaces 12a, 12b of the piston and by the
adjacent surfaces 15a, 15b of the section 13; the surfaces 15a, 15b
make an angle of close to or exactly 90.degree. and lie flush
against the respective surfaces 12a, 12b. The end portion 12 of the
piston 5 is stepped, i.e., it includes a first cylindrical part
having a rectangular cross-sectional outline and being adjacent the
guide 3 (this first cylindrical part is partially bounded by the
surface 12a) and a second part extending from the retainer 11 to
the guide 3 and bounded in part by the surface 12b.
[0038] The form-locking connection (at 16, 17) between the section
13 of the seal 6 and the portion 14 of the retainer 11 cooperates
with the form-locking connection (at 12a, 12b and 15a, 15b) between
the section 13 and the end portion 12 of the piston 5 to ensure
that the orientation of the sections or lips 9, 10 relative to the
piston 5, the housing 2 and the guide 3 remains unchanged
regardless of whether the piston is idle or moves axially of the
housing 2 and guide 3.
[0039] The retainer 11 is provided with a circumferentially
complete or composite projection 21 which is received, preferably
by snap action, in an adjacent recess 19 of the piston 5. The
recess 19 is axially spaced apart from the third section 13 of the
seal 6 and from the bead 16 of the retainer 11; this recess is
dimensioned in such a way that the retainer 11 has limited freedom
of axial movement relative to the piston 5 and vice versa. The
clearance or axial play between the projection 21 and the surfaces
bonding the axial ends of the recess 19 is shown at 29. The
provision of such clearance is desirable or advisable because it
reduces the likelihood of problems due to suction and/or axial
vibrations.
[0040] An advantage of the piston 5 is that its end portion 12 is
provided with a cylindrical end face 13c confronting the adjacent
section or lip 10 of the seal 6. Thus, the configuration of this
end face 12c is similar to that of the cylindrical surface 12b.
Such configuration of the end portion 12 renders it possible to
ensure that the radial forces exerted by the seal 6 upon the piston
5 (when the pressure of hydraulic fluid in the chamber 4 rises) are
normal to the adjacent cylindrical surfaces of the end portion 12;
this is desirable because such orientation of the aforementioned
forces greatly reduces the likelihood of undesirable shifting of
the seal 6 relative to the end portion 12 of the piston 5. The
cylindrical surface 12a of the end portion 12 can be bonded (e.g.,
glued) to the adjacent cylindrical surface 15a of the section 12.
This also applies for the surfaces 12b and 15b.
[0041] The portion 14 of the retainer 11 can be provided with
several concentric axially spaced apart beads 16, and the section
13 of the seal 6 is then provided with an equal number of
complementary grooves 17. Such beads and grooves greatly enhance
the sealing action between the retainer 11 and the seal 6.
[0042] The retainer 11 can be produced or shaped in a deep drawing
machine or it can constitute an extrusion. Such retainer can be
made of steel, aluminum or another suitable metallic material. It
is also possible to employ a laminate containing two or more layers
made of one and the same material or of different materials.
[0043] FIG. 3 illustrates a portion of a second hydraulic clutch
release mechanism wherein the lower end portion of the piston 5 (as
seen in the drawing) is connected with the bearing 27 in a
different way. The fastener 25' comprises a modified snap-on
projection 22' which is received in a socket or recess 20' of the
piston 5. The rigid non-rotatable inner race 35 of the bearing 27
is biased by a diaphragm spring 34 (which reacts against a portion
of the fastener 25') when the piston 5 assumes the end position
which is shown in FIG. 3; the inner race 35 then abuts the
projection 33 of the housing 2. The manner in which the third
section 13 of the seal 6 is form-lockingly connected with the end
portion 12 of the piston 5 and with the portion 14 of the retainer
11 is identical with that described with reference to FIGS. 1 and
2.
[0044] FIG. 4a shows a metallic retainer 11 having a projection 21'
extending into an undercut portion 19' of the piston 5. The manner
in which the portion 14 of the retainer 11 is form-lockingly
connected with the seal (not shown in FIG. 4a) is the same as
described with reference to FIGS. 1 and 2. The same applies for the
form-locking connection between the mutually inclined surfaces 12a,
12b of the end portion 12 of the piston 5 and the third section of
the seal.
[0045] FIG. 4b illustrates a different form-locking connection
between the end portion 12 of the piston 5 and the third section 13
of the seal 6 (not shown in FIG. 4b). The end portion 12 has an
annular recess 18 which is provided in the surface 12a and receives
a complementary bead of the third section (12) of the
non-illustrated seal. The connection 19', 21' between the retainer
11 and the piston 5 is the same as the aforedescribed connection
shown in FIG. 4a. The form-locking connection between the end
portion 12 of the piston 5 of FIG. 4b and the third section of the
non-illustrated seal is even more reliable than those described in
FIGS. 1-2, 3 and 4a. The two form-locking connections (one of which
includes the bead 16 and the other of which includes the recess 18)
are or can be mirror images of each other.
[0046] In accordance with a modification, the form-locking
connection between the retainer 11 and the third section 13 of the
seal 6 and/or between the third section 13 and the end portion 12
of the piston 5 can be established by resorting to a crimping or
burnishing technique.
[0047] FIG. 5a shows a portion of a further hydraulic clutch
release mechanism wherein the retainer 11" is made (e.g., in an
extruder) of a suitable synthetic plastic material. This retainer
is bonded (e.g., welded or glued) to the seal 6 and to the end
portion 12 of the piston 5 against axial movement relative thereto.
The form-locking connection (including the recess 18) between the
section 13 of the seal 6 and the end portion 12 of the piston 5 is
identical with or similar to that shown in FIG. 4b. That portion of
the plastic retainer 11" which is bonded to the piston 5 is stepped
to increase the area of contact.
[0048] The recess 18 and that portion of the section 13 which fills
this recess contribute to the stability of this embodiment of
form-locking connection between the section 13 of the seal 6 and
the end portion 12 of the piston 5.
[0049] FIG. 5b shows a modified plastic retainer 11'" and a
coupling device 24 which fixes the retainer to the adjacent portion
of the piston 5. The coupling device 24 has a radially extending
leg 31 a first portion of which extends (with axial play) into the
recess or socket 19 of the piston 5. A second portion of the leg 31
extends into an opening 23 of the retainer 11'". The latter can be
bonded (such as welded or glued) to the seal 6 and/or to the
adjacent portion of the piston 5. The coupling device 24 is or can
be installed in the recess 19 and/or in the opening 23 in a
radially prestressed condition. The extent of possible radial play
between the leg 31 of the coupling device 24 and the piston 5 is
shown at 29.
[0050] The radially extending surface 15a of the piston 5 serves to
take up radial forces acting between the end portion 12 of the
piston 5 and the section 13 of the seal 6 shown in FIG. 5b. This
also applies for the embodiments of FIGS. 1-2, 3 and 4a.
[0051] The plastic retainers 11",11'" shown in FIGS. 5a and 5b can
constitute extrusions. Such retainers can be made of any one of a
variety of suitable synthetic plastic materials which can be
readily bonded to the adjacent surfaces of normally or often
preferably plastic seal 6 and/or piston 5.
[0052] As already mentioned hereinbefore, the form-locking
connection(s) between the section 13 of the seal 6 and the adjacent
portion of the retainer (such as the portion 14 of the retainer 11
shown in FIGS. 1-2, 3, 4a and 4b) can be established by resorting
to a crimping, beading, or burnishing technique. Other modes of
establishing such or similar or equivalent form-locking connections
include bonding (such as welding or the resort to a suitable
adhesive) as well as the utilization of resilient parts which can
be reliably coupled to each other by snap action. If the retainer
(such as 11" or 11'") is made of a plastic material, it is or it
can be ultrasonically welded to the seal 6 and/or to the piston 5.
The connection between the retainer and the section 13 of the seal
6 and/or the adjacent portion of the piston can be
circumferentially complete or can consist of several parts, e.g.,
of a ring-shaped array of discrete connections.
[0053] An important advantage of the improved clutch release
mechanism is that the third section 13 of the seal 6 is
form-lockingly connected with the retainer 11, 11" or 11'" and
preferably also with the adjacent end portion 12 of the piston 5.
This not only enhances the quality of the connection between the
seal 6 on the one hand, and the piston 5 and the retainer 11, 11"
or 11'" on the other hand, but such connection further reduces the
likelihood of undesirable changes of orientation of the sections 9,
10 relative to the housing 2 and guide 3.
[0054] Another advantage of the improved clutch release mechanism
is that it can dispense with a discrete carrier for the seal 6.
Moreover, the entire axial length of the piston 5 remains available
for guidance of the seal 6 and for displacement of the release
bearing 27.
[0055] The radial play between the retainer and the piston (refer,
for example, to FIGS. 1-3 and 5b) is preferably selected in such a
way that it permits a preselected range of radial movements of the
retainer (and hence of the seal 6) relative to the piston. This
reduces or eliminates several problems, such as those due to
suction and/or vibrations.
[0056] The features which distinguish the illustrated embodiments
from each other and/or the features which are characteristic of
certain specific embodiments of the present invention can be
utilized individually, exchangeably and/or in any desired practical
combination with each other. For example, the coupling device 24 of
FIG. 5b can be utilized in the embodiment of FIG. 5a or as a
substitute for projection 21 and vice versa. Furthermore, the
plastic retainer 11'" can be replaced with a metallic retainer, the
embodiment of FIG. 5b can employ several coupling devices and so
forth.
[0057] Without further analysis, the foregoing will so fully reveal
the gist of the present invention that others can, by applying
current knowledge, readily adapt it for various applications
without omitting features that, from the standpoint of prior art,
fairly constitute essential characteristics of the generic and
specific aspects of the above outlined contribution to the art of
hydraulic release mechanisms, especially of release mechanisms for
friction clutches in the power trains of motor vehicles and,
therefore, such adaptations should and are intended to be
comprehended within the meaning and range of equivalence of the
appended claims.
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