Title: Clutch release mechanism with a device for compensating for lack of precision in a friction clutch of a motor vehicle
Abstract: A clutch-release mechanism for actuating the friction clutch of a motor vehicle, installed concentrically around a guide sleeve, includes a release bearing with an inner ring and an outer ring as well as a sliding sleeve. The inner ring is in working contact with a release spring of the friction clutch and the outer ring is in working contact with the sliding sleeve by way of a sliding surface, and the release mechanism has both a first device for compensating for a tilt of the center axis of the friction clutch with respect to the center axis of the guide sleeve and/or for a wobbling eccentricity of the release spring, and a second device for compensating for an offset between the above-mentioned center axes. The first device consists of a modified raceway for the balls, where the race has both a first race radius and a second race radius to form a surface in the form of a spherical segment, where differences between the angles of the release spring and of the release bearing are compensated. Because the raceway can be produced in any case with high precision in the outer ring and because the rolling contact of the parts is lubricated with grease and protected from the outside environment by seals, no additional components are required for the release mechanism, and there are no additional friction points to be lubricated and sealed.
Patent Number: 6,997,619 Issued on 02/14/2006 to Reuter
| Inventors:
|
Reuter; Klaus (Oberthulba-Hetzlos, DE)
|
| Assignee:
|
ZF Sachs AG (Schweinfurt, DE)
|
| Appl. No.:
|
465082 |
| Filed:
|
June 19, 2003 |
Foreign Application Priority Data
| Current U.S. Class: |
384/615 |
| Current Intern'l Class: |
F16C 19/10 (20060101) |
| Field of Search: |
384/615,612,617,620,609
|
References Cited [Referenced By]
U.S. Patent Documents
| 6126324 | Oct., 2000 | Ponson et al.
| |
| Foreign Patent Documents |
| 0 241 810 | Oct., 1987 | EP.
| |
| 2 805 579 | Aug., 2001 | FR.
| |
| 2 339 000 | Jan., 2000 | GB.
| |
Primary Examiner: Footland; Lenard A.
Attorney, Agent or Firm: Cohen, Pontani, Lieberman & Pavane
Claims
What is claimed is:
1. A clutch release bearing for installation around a guide sleeve mounted on
a transmission shaft between an internal combustion engine and a transmission in
a motor vehicle, said friction clutch and said guide sleeve having respective center
axes, said bearing comprising:
an inner ring having an inner race, said inner ring, when installed, being in
working connection with one of said friction clutch and said guide sleeve; and
an outer ring having an outer race, said outer ring, when installed, being in
working connection with the other of said friction clutch and said guide sleeve; and
a plurality of balls between said inner race and said outer race;
wherein one of said inner race and said outer race has a first race portion with
a first race radius and a second race portion with a second race radius which is
larger than said first race radius, said radii lying in a plane containing said
central axis of said guide sleeve, said second race radius being centered on the
center axis of the guide sleeve.
2. A clutch release mechanism as in claim 1 wherein said bearing is an angular
contact bearing, said first race radius having a conventional osculation with respect
to said balls.
3. A clutch release bearing as in claim 1 wherein said one of said races has
two said first race portions, said second race portion interrupting said first
race portions.
4. A clutch release bearing as in claim 1 wherein said outer race has said first
and second race portions.
5. A clutch release bearing as in claim 4 wherein said second race portion has
a width which defines a deflection angle about which said second ring can oscillate
relative to said first ring.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a clutch release mechanism for actuating a friction
clutch between an internal combustion engine and a transmission of a motor vehicle.
This mechanism is installed as concentric assembly around a guide sleeve mounted
on a transmission shaft, comprising a release bearing with an inner ring and an
outer ring as well as a sliding sleeve, where one of the rings, preferably the
inner ring, is in working connection with a release spring of the friction clutch
and the outer ring is in working connection with the sliding sleeve. The assembled
release mechanism has a first device for compensating for a tilt of the center
axis of the friction clutch with respect to the center axis of the guide sleeve
and/or for a wobbling eccentricity of the release spring and a second device for
compensating for an offset between the previously mentioned center axes.
2. Description of the Related Art
DE 199 12 431 A1 (equivalent to UK patent application GB 2 339 000) discloses
a clutch release mechanism for a friction clutch of a motor vehicle. This mechanism
includes a release bearing, which is mounted on a sliding sleeve, and a disk spring,
which belongs to the friction clutch and is in working connection with the release
bearing. Particularly, the disclosed mechanism includes two areas with complementary
surfaces in the form of segments of a sphere which are provided between the disk
spring and the release bearing. The two areas with the surfaces in the form of
spherical segments are provided directly or indirectly on the disk spring, and
the areas forming the surfaces in the form of spherical segments can be shifted
radially toward the release bearing.
The areas connected in this way by surfaces in the form spherical segments are
slide on each other and are formed from in part by the tongues or a compensating
ring which is mounted between the disk spring and a flange part provided to serve
as the pressure plate of the release bearing. In addition, the spherical surfaces
on the rings are produced primarily by a grinding process, which increases costs
related to both the production and the material of the rings.
SUMMARY OF THE INVENTION
As the first device for compensating for a tilt of the center axis of the friction
clutch with respect to the center axis of the guide sleeve and/or for a wobbling
eccentricity of the release spring, the proposed clutch-release mechanism according
to the invention has a modified race for the balls of the release bearing, preferably
in the outer ring. As is known in the art, this race includes a first race radius,
which, as the osculation radius, is only slightly larger than the radius of the
balls. According to the present invention, this race radius is interrupted by a
second race radius, which is much larger than the osculation radius and has its
starting point on the center axis of the guide sleeve. It can be concluded from
the fact that the second race radius has its starting point on the center axis
of the guide sleeve that the ring-shaped surface formed by the second race radius
is a surface in the form of a spherical segment, which, in functional terms, represents
a ball joint for the inner ring. As an angular-contact ball bearing with the ability
to oscillate, the inner ring of the release bearing can therefore react to an eccentric
wobbling of the release spring by following the imprecise course of the rotating
tongues during which process the balls in the spherically shaped surface of the
first race radius do not roll in a plane perpendicular to the center axis of the
guide sleeve but rather along a track which is at an angle to this plane. This
track, which oscillates from one side to another, can deflect only as far as a
specific maximum deflection angle, where the width of the surface in the shape
of a spherical segment is determined by the adjacent halves of the first race radius.
The force exerted by the balls on the spherical surface depends on the position
of the second race radius, where the resulting bearing pressure angle decreases
as the starting point of the second race radius moves closer to the release bearing.
According to the present invention, a second device has a sliding surface
between the release bearing and the sliding sleeve in a plane perpendicular to
the center axis of the guide sleeve to compensate for an offset between the center
axis of the friction clutch and the center axis of the guide sleeve. The release
bearing can be pushed along this sliding surface with respect to the sliding sleeve
within certain limits and, thus, can be moved out of its coaxial position with
respect to the guide sleeve. The two devices can be combined in one release mechanism,
it being advisable in this case for the release bearing to accompany the movements
of the clutch spring by virtue of the contact of the rotating inner ring of the
bearing with the tongues of the clutch spring, for which reason the two devices
must be installed between the release bearing and the guide sleeve.
The sliding surface of the release mechanism described above is located on the
outer ring of the release bearing in a plane perpendicular to the center axis of
the guide sleeve, where, within certain limits, the release bearing can be pushed
along the sliding of the sliding sleeve and thus moved out of a position coaxial
with respect to the guide sleeve. Because the release bearing and the sliding sleeve
are connected elastically together by a clamp, static friction is created, which
stabilizes the release bearing when it has moved off-center. A ring-shaped stop
is provided on the sliding surface of the sliding sleeve. The outer ring can make
contact with this stop, which limits the extent to which the outer ring can be
deflected from its centered position.
It is an object of the present invention to provide a clutch-release mechanism
for actuating the release spring of a friction clutch of a motor vehicle which
has a device for compensating for a tilt of the center axis of the friction clutch
with respect to the center axis of a guide sleeve and/or for compensating for an
offset of the above-mentioned center axes and/or for a wobbling eccentricity of
the release spring. Preferably, such a mechanism occupies a minimal amount of space
and has a minimal cost.
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
FIG. 1 is a cross-sectional view of a clutch-release mechanism with a sliding
sleeve and a release bearing with an outer ring and an inner ring, the mechanism
also including a common slide face between the outer ring and the sliding sleeve
in a phase perpendicular to the center axis of the sliding sleeve; and
FIG. 2 is a partial cross-sectional view of the outer ring with a race consisting
of several segments.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
FIG. 1 shows a clutch-release mechanism
50 for actuating a friction clutch
using a release spring
5. The release mechanism
50 has a release
bearing
1, which is a ball bearing with an inner ring
3, balls
8,
and an outer ring
6. The inner ring
3 rests by a contact surface
4 against the tongues of the release spring
5. The outer ring
6
has a sliding surface
7 indirectly or directly in common with a sliding
sleeve
2 in a plane
14 transverse to the center axis of the release
bearing
1. The sliding sleeve has a ring-shaped stop
15 for the outer
ring
6 of the release bearing
1. A clamp
16 connects the release
bearing
1 to the sliding sleeve
2 to form a structural unit.
In FIG. 2, the outer ring
6 has a race
9 which includes a ring-shaped
surface with a first race radius
10, an intermediate ring-shaped surface
with a second race radius
11, and an inner ring-shaped surface, again with
the first race radius
10. As the balls
8 rotate in the outer ring
6, they can move within a deflection angle
13. They are guided in
a conventional race in the inner ring
3.
The advantage of the first device consists in that only the race
9 for
the balls
8 must be modified, preferably in the outer ring
6, in
that a second race radius
11 is machined into the ring next to a first race
radius
10 to form a surface in the form of a spherical segment, where differences
between the angle of the release spring
5 and the angle of the release bearing
1 can thus be compensated. Because the race
9 can be in any case
produced in the outer ring
6 with high precision and because the rolling
contact between the parts is lubricated with grease and protected by seals from
the outside environment, no additional components are required for the release
mechanism, and no additional friction points are present which must be lubricated
and sealed.
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 and/or
method steps 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 and/or method steps 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.
*
