U.S. patent application number 10/864170 was filed with the patent office on 2004-12-23 for ball-and-socket joint with bearing shell.
This patent application is currently assigned to TRW Fahrwerksysteme GmbH & Co. KG. Invention is credited to Dorr, Christoph.
Application Number | 20040258463 10/864170 |
Document ID | / |
Family ID | 7918537 |
Filed Date | 2004-12-23 |
United States Patent
Application |
20040258463 |
Kind Code |
A1 |
Dorr, Christoph |
December 23, 2004 |
Ball-and-socket joint with bearing shell
Abstract
A ball-and-socket joint includes a joint housing having first
and second axial ends and a ball head provided with a ball stud
that extends from the ball head. A bearing shell has elastic
properties and is received in the joint housing whereby the bearing
shell receives the ball head. The ball stud extends outward of the
first axial end of the joint housing. The ball-and-socket joint
also includes a housing cover for closing the second axial end of
the joint housing and a spring element that is interposed between
the housing cover and at least a portion of the bearing shell. The
spring element preloads the portion of the bearing shell to urge
the portion of the bearing shell toward the first axial end of the
joint housing thereby plastically deforming the portion of the
bearing shell into its final ball-shaped contour.
Inventors: |
Dorr, Christoph;
(Schermbeck, DE) |
Correspondence
Address: |
TAROLLI, SUNDHEIM, COVELL, TUMMINO & SZABO L.L.P.
1111 LEADER BLDG.
526 SUPERIOR AVENUE
CLEVELAND
OH
44114-1400
US
|
Assignee: |
TRW Fahrwerksysteme GmbH & Co.
KG
|
Family ID: |
7918537 |
Appl. No.: |
10/864170 |
Filed: |
June 9, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10864170 |
Jun 9, 2004 |
|
|
|
09640038 |
Aug 16, 2000 |
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Current U.S.
Class: |
403/137 |
Current CPC
Class: |
Y10T 403/32721 20150115;
F16C 11/0638 20130101; Y10T 403/32762 20150115; Y10T 403/32778
20150115; F16C 2326/01 20130101; Y10T 403/32745 20150115; F16C
11/0642 20130101; Y10T 403/32754 20150115 |
Class at
Publication: |
403/137 |
International
Class: |
F16D 001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 16, 1999 |
DE |
199 38 770.2 |
Claims
1-16. (Cancelled)
17. A ball-and-socket joint comprising: a joint housing having
first and second axial ends; a ball head provided with a ball stud
extending from the ball head; a bearing shell having elastic
properties and being received in the joint housing whereby
receiving the ball head, the ball stud extending outward of the
first axial end of the joint housing; a housing cover for closing
the second axial end of the joint housing; and a spring element
interposed between the housing cover and at least a portion of the
bearing shell preloading the portion of the bearing shell to urge
the portion of the bearing shell toward the first axial end of the
joint housing thereby plastically deforming the portion of the
bearing shell into its final ball-shaped contour.
18. The ball-and-socket joint as claimed in claim 17 wherein the
spring element advances the portion of the bearing shell toward the
first axial end of the joint housing for wedging the portion of the
bearing shell further into a gap formed between the ball head and
the joint housing adjacent the ball stud at the first axial end of
the joint housing as wear to the portion of the bearing shell
occurs.
19. The ball-and-socket joint as claimed in claim 17 wherein the
spring element is a disk that is arranged between the housing cover
and the bearing shell, wherein center portions of both the housing
cover and the disk extend outwardly away from the ball stud.
20. The ball-and-socket joint as claimed in claim 19 wherein the
housing cover is made of a plastically deformable material, the
center portion of the housing cover being axially deformable toward
the ball stud.
21. The ball-and-socket joint as claimed in claim 20 wherein the
center portion of the housing cover contacts the center portion of
the disk to urge the disk against the bearing shell.
22. The ball-and-socket joint as claimed in claim 17 wherein the
bearing shell includes a deformable area, the deformable area
enabling the bearing shell to be adapted for use with joint
housings of varying tolerances.
23. The ball-and-socket joint as claimed in claim 17 wherein the
bearing shell includes separate and distinct first and second
parts, the first part being an upper shell and,the second part
being a lower shell.
24. The ball-and-socket joint as claimed in claim 23 wherein the
spring element is arranged between the upper shell and the lower
shell, the lower shell being the portion of the bearing shell that
is plastically deformed.
25. The ball-and-socket joint as claimed in claim 24 wherein the
spring element is a wave-shaped spring washer.
26. A ball-and-socket joint comprising: a joint housing having
first and second axial ends; a ball head provided with a ball stud
extending from the ball head; a bearing shell receivable in the
joint housing for supporting the ball head in the joint housing for
pivotal movement relative to the joint housing, the bearing shell
supporting the ball head so that the ball stud extends out of the
first axial end of the joint housing; a housing cover for closing
the second axial end of the joint housing; and a spring element
interposed between the housing cover and at least a portion of the
bearing shell, the spring element urging the portion of the bearing
shell toward the first axial end of the joint housing and, as wear
to the portion of the bearing shell occurs, wedging the portion of
the bearing shell into a gap formed between the ball head and the
joint,housing adjacent the first axial end of the joint housing so
as to compensate for the wear, the portion of the bearing shell,
prior to being assembled into the joint housing, having a
cylindrical contour and, upon being assembled into the joint
housing and being subjected to a preloading force, plastically
deforming into a ball-shaped contour.
Description
[0001] The present invention relates to a ball-and-socket joint
comprising a joint housing, a ball head with ball pivot, a bearing
shell arranged between ball head and joint housing, and a housing
cover.
[0002] Ball-and-socket joints of said type are known in the art and
are preferably used in motor vehicles. The ball head of the
ball-and-socket joint is rotatably and tiltably supported in the
bearing shell, and the bearing shell in turn is arranged in the
joint housing.
[0003] The purpose of the bearing shell, which is usually exposed
to hard wear, is to compensate the lateral forces acting on the
ball-and-socket joint and to absorb shocks to the joint housing and
to the ball pivot. The bearing shell is therefore advantageously
made of an elastic plastic that can be elastically deformed as a
result of the forces acting on the ball-and-socket joint.
[0004] To ensure that the ball head is not enclosed too tightly by
the bearing shell during assembly of a ball-and-socket joint of the
initially mentioned type and that the joint is not too stiff, tight
manufacturing tolerances are required particularly in the
production of the joint housing. To compensate stiffness of the
ball-and-socket joint due to imprecise manufacturing tolerances, a
bearing shell has been proposed, which at one end face is provided
with very small projections whose height slightly exceeds the
manufacturing tolerances of the joint. These projections are
deformed when correspondingly high forces are applied as the joint
is assembled and have the purpose of compensating the manufacturing
tolerances of the joint members such that the tolerance for free
movement of the ball-and-socket joints can be kept within limits.
However, wear of the bearing shell cannot be compensated by these
projections.
[0005] With increasing wear of the bearing shell, an undesirable,
continuously increasing bearing clearance develops between ball
head and bearing shell. With respect to the operating life of the
ball-and-socket joint this causes a change in the motive torques of
the bearing journal as well as a continuous change in the
elasticity properties of the bearing shell. As a consequence, the
bearing is no longer exact, which results in imprecise wheel
guidance of the ball-and-socket joint and noise development.
[0006] Thus, based on this prior art, the object of the present
invention is to further develop a ball-and-socket joint of the
initially mentioned type to reduce the tolerance of free movement
and increase the life of the ball-and-socket joint while
simultaneously simplifying the assembly.
[0007] To attain this object, it is proposed according to the
invention that a compressive force, which is produced between the
housing cover and at least a portion of the bearing shell and
axially acts in the direction of the ball pivot, permanently acts
on this portion of the bearing shell and presses it into the gap
between ball head and joint housing.
[0008] This ball-and-socket joint designed according to this
technical teaching advantageously allows the compensation of
inaccuracies that are due to manufacturing tolerances of the joint
members as well to wear. Unlike in prior art processes, the
ball-and-socket joint according to the invention is assembled with
an intentional axial clearance of the bearing shell in relation to
the rolled-in housing cover with respect to both maximum and
minimum manufacturing tolerances. The compressive force, which on
the cover-side permanently acts in axial direction of the ball
pivot on at least a portion of the bearing shell, presses this
portion of the bearing shell into the gap between ball head and
ball-and-socket joint such that, independent of the different
manufacturing tolerances of the individual ball-and-socket joint
components, the ball head is supported in the bearing shell under
the action of axial forces that are always the same so that
different freedoms of movement of the ball joints are avoided. The
compressive force can be applied to the bearing shell either
directly below the housing cover or it can act on any intersection
line or plane as a part of the bearing shell. Due to tolerance
compensation, the motive torques of the ball-and-socket joint and
the elastic properties of the bearing shell are thus largely
independent of the manufacturing process and the resultant
manufacturing tolerances of the joint members. Furthermore, the
tilting torque of the ball-and-socket joint and the elasticities of
the bearing shell can be adjusted in an advantageous manner by
correspondingly selecting the compressive force acting on the
bearing shell after assembly of the ball-and-socket joint. This
makes it possible to produce ball-and-socket joints with low motive
torques and elasticities while keeping dimensional tolerances
acceptable in terms of process engineering with less variation of
the joint properties.
[0009] The ball-and-socket joint according to the invention also
advantageously compensates wear of the bearing shell. The
compressive force permanently acting on the bearing shell causes
the bearing shell to advance continuously as wear occurs, such
that, in terms of a "self adjustment" of the bearing shell, the
ball head is always supported in the bearing shell under the action
of identical axial-elastic wedge effects. This ensures largely
constant motive torques of the ball-and-socket joint on the one
hand and essentially unchanging elastic properties of the bearing
shell on the other hand, which advantageously increases the life of
the ball-and-socket joint.
[0010] To produce the compressive force permanently acting on the
bearing shell, the present invention proposes plastically to deform
the housing cover in axial direction of the ball pivot with a
specifically definable force. A disk made of an elastic material
and disposed between housing cover and bearing shell is elastically
deformed by the plastic deformation of the housing cover. This
generates a preloading force that is applied to the bearing shell
as a permanently acting compressive force. Thus, a defined pressing
in of the housing cover makes it possible to achieve an exactly
definable preloading force of the ball-and-socket joint. According
to a particular advantage of the invention, both the housing cover
and the disk have an outwardly facing trapezoidal curvature. The
inside [ . . . ] and of the housing cover [sic] rests against and
fully contacts the disk in the area of the trapezoidal curvature
based on a defined applied force and a deformation of the housing
cover. This effect can furthermore be enhanced in that the torque
of the ball pivot is measured or monitored as the housing cover is
pressed in, and the measured data is used to control the
pressing-in force.
[0011] According to an alternative embodiment, the compressive
force permanently acting on the bearing shell is produced by means
of a spring that is arranged between the housing cover and the
bearing shell and supported against the joint housing via the
housing cover. With particular advantage, it is proposed that the
spring is a trapezoidal disk spring with an outward curvature. When
the joint housing is closed with a rigid housing cover, the disk
spring disposed between bearing shell and housing cover is
compressed and the resultant spring force permanently acts on the
bearing shell in axial direction of the pivot pin in the form of a
compressive force. By selecting a corresponding disk spring and its
initial stress, the disk spring force and thus also the preloading
force of the ball-and-socket joint can be adjusted. According to a
further advantageous proposal of the invention, an additional load
transmission disk may be disposed between disk spring and bearing
shell to optimize introduction of the force into the bearing shell.
In a further advantageous embodiment, the contact area between
spring and disk is designed as a deformable area. During assembly,
after flattening of the spring, this area is deformed to a
sufficient degree until the bearing shell has reached its axial end
position. The initial preloading of the joint is thus independent
of the tolerances of the individual components and the size of the
spring force.
[0012] According to an alternative embodiment, the bearing shell
arranged between ball head and joint housing has a two-part design
and is divided into an upper shell and a lower shell. This
partitioning of the bearing shell into two parts advantageously
creates two mutually independent functional areas that may be
designed according to the requirements they are intended to meet.
For example, the upper shell serves to compensate the inaccuracies
due to the manufacturing tolerances of the joint members, whereas
the lower shell compensates wear.
[0013] To compensate the inaccuracies due to the manufacturing
tolerances in the assembly of the ball joint, the invention
proposes that the upper shell, on the housing cover side, be
provided with a collar, which in the assembled state of the
ball-and-socket joint is wedged between the housing cover and a
housing shoulder. To assemble the ball-and-socket joint, a
compressive force acting in axial direction of the ball pivot is
generated on the cover side and applied via the housing cover to
press the bearing shells into the gap between ball head and
housing. The compressive force acting during assembly is
transmitted from the upper shell to the lower shell. The
inaccuracies due to the manufacturing tolerances of the joint
members can be compensated due to a plastic deformation of the
collar arranged between the actual upper shell and the housing
cover. The axial end position of the upper and lower shell is
established as a function of the tolerances of the individual
components, such that, irrespective of manufacturing tolerances,
the ball head is supported in the bearing shell and different
freedoms of movement of the ball-and-socket joints are avoided.
[0014] According to a further feature of the invention, to
compensate wear of the bearing shell, a spring element is disposed
in axial direction between upper shell and lower shell. In the
assembled state, this spring element is supported against the
housing cover via the upper shell and produces a compressive force
permanently acting on the lower shell, which causes a continuous
advancement of the lower shell as wear occurs. This allows a
"self-adjustment" of the lower shell of the ball head under the
action of axial-elastic wedge effects that remain always the same
and achieves, on the one hand, motive torques that are largely
constant and on the other hand essentially unchanged elastic
properties of the bearing shell. This advantageously prolongs the
life of the ball-and-socket joint. According to a further feature
of the invention, the spring element disposed between upper shell
and lower shell is a spring washer of a wave-shaped design that is
pushed up completely after assembly and thus can transmit the full
magnitude of the assembly compressive force to the lower shell.
[0015] Insertion of the bearing shell into the joint housing can be
carried out in separate consecutive steps, or the individual
components, lower shell, spring element and upper shell, can be
combined into a packet and inserted into the joint housing as a
unit in a single assembly step. To form the assembly packet, the
upper and lower shell can be fabricated in a common injection mold
with a corresponding recess being provided to receive the spring
element that separates the lower shell from the upper shell.
Irrespective of whether the bearing shell is assembled in a single
step or in multiple steps, it has proven to be advantageous to give
the lower shell a cylindrical contour prior to its assembly and in
contrast to its embodiment after completed assembly.
[0016] Further details and advantages of the invention will become
clear from the following description by means of the drawings in
which
[0017] FIG. 1 is a sectional view of a ball-and-socket joint with
an integrally formed housing cover,
[0018] FIG. 2 is a sectional view of a ball-and-socket joint with a
disk spring disposed between bearing shell and housing cover
according to a first embodiment,
[0019] FIG. 3 is a sectional view of a ball-and-socket joint with a
disk spring disposed between bearing shell and housing cover
according to a second embodiment,
[0020] FIG. 4 is a sectional view of a ball-and-socket joint with a
two-part bearing shell and a spring washer,
[0021] FIG. 5 is a three-dimensional view of the spring washer
according to FIG. 4.
[0022] The ball-and-socket joint depicted in FIG. 1 essentially
comprises a ball head 2 with integrally formed ball pivot 3 and a
joint housing 1 sealed with a housing cover 5. The ball head 2 is
supported in a bearing shell 4, which in turn is arranged in joint
housing 1. The bearing shell 4 is designed as one piece, contacts
the ball head 2 with its sliding surface 7 on both sides of the
equatorial plane 8 and supports it.
[0023] As the ball-and-socket joint is assembled, a precisely
defined force F.sub.v is applied to the housing cover 5 provided
with an outwardly facing trapezoidal curvature, which causes a
plastic deformation of the housing cover 5 in the area of the
trapezoidal curvature. In this figure, force F.sub.v is indicated
by a dashed line. Based on this plastic deformation of the housing
cover 5, the disk 6 disposed between bearing shell 4 and housing
cover 5 is elastically deformed and applies a permanent compressive
force to the bearing shell 4 in axial direction of the ball pivot
3. This causes bearing shell 4 to be pressed into the gap between
joint housing 1 and ball head 2. This has the advantage that the
ball-and-socket joint is not susceptible to manufacturing
tolerances of the joint members, particularly of joint housing 1
and ball head 2, and that the preloading force of the
ball-and-socket joint can be adjusted by means of the precisely
defined pressing-in force F.sub.v. The motive torques of the
ball-and-socket joint, which are determined by the preloading force
as well as the elastic properties of the bearing shell 4 can thus
also be specifically adjusted via the pressing-in force F.sub.v
irrespective of the manufacturing tolerances. This makes it
possible to produce a ball-and-socket joint with low motive torques
and elasticities, which despite acceptable dimensional tolerances
in terms of process engineering has a narrow variation range with
respect to the motive torques and the elasticities. As wear occurs
in the bearing shell 4, the compressive force permanently acting on
the bearing shell causes the bearing shell 4 to advance into the
gap between ball head 2 and joint housing 1. This "self-adjustment"
of the bearing shell 4 ensures nearly identical motive torques and
elasticity properties despite wear. Prior to assembly, the bearing
shell preferably has a cylindrical contour 23 on the pivot side,
which only after assembly is plastically deformed into its final
ball-shaped contour.
[0024] In the embodiment of the ball-and-socket joint according to
the invention shown in FIG. 2, the compressive force permanently
acting on the bearing shell 4 in axial direction of the ball pivot
3 is produced by means of a disk spring 9 disposed between bearing
shell. 4 and housing cover 5. For better force application to the
bearing shell 4, a load transmission disk 6 is arranged between
disk spring 9 and bearing shell 4. The desired preloading force of
the ball-and-socket joint can be adjusted through a corresponding
selection of the disk spring properties. As described above, the
compressive force generated by the disk spring 9 and transmitted to
the bearing shell 4 also serves to press the bearing shell 4 into
the gap between the ball head 2 and joint housing 1. Consequently,
the ball-and-socket joint is not susceptible to manufacturing
tolerances on the one hand, and the wear contour 10 is compensated
by an axial advance of the bearing shell on the other hand. The
embodiment of the joint housing 1 shown in FIG. 2 has a
substantially cylindrical inner contour starting from the
equatorial plane 8 of the ball head 2 toward the cover-side end.
This inner contour, according to a special embodiment of joint
housing 1, can be conical with a tapering diameter in the direction
of the equatorial plane 8 of the ball head 2. This is indicated by
the dashed line 11. If a joint housing 1 with conical inner contour
is used, the bearing shell 4 is correspondingly adapted. The
conical embodiment of the inner contour advantageously reduces the
torque of the ball-and-socket joint caused by the permanently
acting compressive force of the spring 9. According to a further
embodiment of the ball-and-socket joint, an elastic ring made of
rubber is disposed between bearing shell 4 and housing cover 5
instead of the disk spring 9.
[0025] In a further preferred embodiment, the contact area between
spring 9 or disk 6 is made as a deformable area 24. During
assembly, this area, after flattening of the spring, is deformed to
a sufficient degree until the bearing shell 4 has reached its axial
end position. The initial preloading of the joint is thus
independent of the tolerances of the individual components and the
size of the spring force.
[0026] FIG. 3, according to a second embodiment, also shows a
ball-and-socket joint with a spring disk 9 disposed between bearing
shell 4 and housing cover 5. In contrast to the embodiment depicted
in FIG. 2, a circumferential collar 17 is provided instead of a
load transmission disk disposed between disk spring 9 and bearing
shell 4. In the assembled state of the ball-and-socket joint this
collar 17 rests against the disk spring 9 and transmits the
compressive force generated by the disk spring 9 to the bearing
shell. The circumferential collar 17 and the bearing shell are
designed as one piece, but in contrast to the embodiment shown in
FIG. 2, the bearing shell is formed as a closed bearing shell 12.
The collar 17 is provided with a shoulder 18 and with snap locking
means 19 for a secure seat of the disk spring 9. As explained above
in connection with the embodiment according to FIG. 2, the desired
preloading force of the ball-and-socket joint can be adjusted via a
corresponding selection of the disk spring properties in this
embodiment as well.
[0027] FIG. 4 shows an embodiment of the ball-and-socket joint
according to the invention with a two-part design of the bearing
shell comprising an upper and a lower shell 13, 14, and 15. The
embodiment depicted on the left of the drawing shows an upper shell
15 with an open design and the embodiment depicted on the right
half of the figure shows an upper shell 14 with a closed design.
The upper shell 14, 15 has an integrally formed circumferential
collar 17 on the cover side, which in the assembled state of the
ball-and-socket joint is wedged between the housing cover 5 and the
housing shoulder 20. This circumferential collar 17 has deformable
areas 21 and 22 that have a tolerance compensating effect on the
axial position of the upper and lower shell 14, 15, 16 when the
joint is assembled. To compensate wear of the bearing shell, a
spring element in the form of a wave-shaped washer 16, is provided
between the upper shell 14, 15 and the lower shell 13. This spring
washer 16 is supported against the housing cover 5 via the upper
shell 14,.15 and applies a compressive force permanently acting on
the lower shell 13, which causes the lower shell 13 continuously to
advance as wear occurs. This "self adjustment" of the lower shell
13 makes it possible that the ball head 2 is supported in the
bearing shell 12 under the action of axial-elastic wedge effects
that remain always the same. During assembly, this spring washer is
flattened and the full magnitude of the assembly compressive force
is thereby transmitted from the upper to the lower shell.
[0028] In contrast to the embodiments depicted in FIG. 1 to 3, the
two-part embodiment of bearing shell 12 has the effect of a
functional division. The upper shell 14, 15 with its integrally
formed rim 17 serves to compensate inaccuracies due to
manufacturing tolerances, whereas the lower shell 13 compensates
wear. With this function-related division between upper and lower
shell 13, 14, 15 and the arrangement of a spring washer 16 between
upper and lower shell 13, 14, 15, the spring force required for the
advancement of the shell is advantageously reduced substantially so
that low motive torques can be realized.
[0029] FIG. 5 is a three-dimensional representation of the
wave-shaped spring washer 16 between upper and lower shell 13, 14,
15 in its non-stressed state. Under the action of the pressing-in
force that is applied to the bearing shell during assembly, ring 16
is compressed and thereafter tries to expand in axial direction to
assume the non-stressed state depicted in FIG. 5. Due to this
expansion tendency of the spring washer 16, the lower shell 13 is
pressed into the gap between ball head 2 and joint housing 1, which
makes it possible to compensate wear of bearing shell 12.
[0030] List of Reference Symbols
[0031] 1 ball-and-socket joint
[0032] 2 ball head
[0033] 3 ball pivot
[0034] 4 bearing shell
[0035] 5 housing cover
[0036] 6 disk
[0037] 7 sliding surface
[0038] 8 equatorial plane
[0039] 9 spring
[0040] 10 wear contour
[0041] 11 dashed line
[0042] 12 closed bearing shell
[0043] 13 lower shell
[0044] 14 closed upper shell
[0045] 15 open upper shell
[0046] 16 spring washer
[0047] 17 collar
[0048] 18 shoulder
[0049] 19 snap locking means
[0050] 20 shoulder
[0051] 21 deformable area
[0052] 22 deformable area
[0053] 23 cylinder-shaped contour
[0054] 24 deformable area Page 3
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