FORM
THE PATENT ACT 1970 (39 of 1970)
&
The Patents Rules, 2 0 03 COMPLETE SPECIFICATION (See Section 10, and rule 13}
1. TITLE OF INVENTION : BALL JOINT
2. APPLICANT(S)

a) Name : ZF FRIEDRICHSHAFEN AG
b) Nationality : GERMAN Company
c) Address : 88038 FRIEDRICHSHAFEN
GERMANY
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -

The invention relates to a ball joint comprising a housing having a spindle opening as well as a ball-ended spindle, which has a joint ball and which is supported movably by means of the joint ball in the housing and extends through the spindle opening out of the housing.
There is frequently the need for a joint that is capable of achieving a wobbling motion, in particular a spatially wobbling track having only one degree of freedom. A ball joint with its three degrees of rotational freedom presents itself for this purpose, two of these degrees of freedom however having to be purposefully cancelled. To achieve a wobbling motion it is possible for example to use a ball joint, in the joint ball surface of which two mutually independent grooves are provided, into which two pins or rollers mounted and fixed on the joint housing engage. These force the joint ball in the course of a movement along a defined track, with the result that it is possible to subject a part connected to the joint ball to a desired spatial motion.
This solution is however very costly as both the forming of the grooves by milling and optionally grinding and the manufacture and assembly of the guide fingers is expensive. The double restricted guidance moreover entails high manufacturing tolerances.
Against this background the underlying object of the invention is to provide a possible way of achieving restricted guidance of a ball-ended spindle of a ball joint that is cost-effective particularly in terms of mass production.
This object is achieved according to the invention by a ball joint according to claim 1. Preferred developments of the invention are indicated in the sub-claims.
The ball joint according to the invention, in particular for a vehicle, comprises a housing provided with a spindle opening as well as a ball-ended spindle, which has a joint ball and which is mounted movably, in particular rotatably and pivotably, in

the housing by means of the joint ball and extends through the spindle opening out of the housing, wherein the joint ball has a non-planar ruled surface that is in contact with a lay-on device provided on the housing.
By virtue of the interaction of ruled surface and lay-on device a restricted guidance of the ball-ended spindle is achieved, which brings about a restriction of the freedom of motion of the ball-ended spindle. In a preferred manner, the shaping of the ruled surface defines a spatial path of motion, along which the ball-ended spindle moves or may be moved when the ball-ended spindle rotates or is rotated about its longitudinal axis. The shaping of the ruled surface provides in particular a dependence between a rotation of the ball-ended spindle about its longitudinal axis and a lateral deflection of the ball-ended spindle about at least one other axis (slewing axis), which is aligned obliquely or at right angles to the longitudinal axis axis [sic] of the ball-ended spindle. In a preferred manner the at least one slewing axis intersects the longitudinal axis of the ball joint, wherein the point of intersection lies preferably in the centre of the joint ball. In particular, the interaction of ruled surface and lay-on device forces the ball-ended spindle, as it rotates about its longitudinal axis, into a lateral deflection. Manufacture of the ruled surface is effected for example by cold pressing, this being possible in a very cost-effective manner in the case of large-scale manufacture. By a ruled surface is meant, mathematically, in particular a surface that may be generated by moving a straight line in space (see I. N. Bronstein and K. A. Semendjajew, Pocketbook of Mathematics, 25th edition 1991, B. G. Teubner Verlag-gesellschaft, Stuttgart, page 605).
A supplementary restriction of the freedom of motion of the ball-ended spindle or a supplementary restricted guidance of the ball-ended spindle may be effected by means of an additional guide, by means of which the ball-ended spindle is guided, in particular forced along a predefined path of motion. The additional guide restricts in particular the possible lateral deflections of the ball-ended spindle and may be formed for example by a gate, through which the ball-ended spindle extends. In a preferred manner, the additional guide is formed by the spindle opening. The

additional guide or spindle opening is preferably of an oblong, in particular oval configuration, which may be realized relatively cost-effectively. By means of the spindle opening and the interaction of ruled surface and lay-on device the possible movements of the ball-ended spindle are restricted preferably to a spatial path of motion, in particular for the execution of a wobbling motion.
The ball-ended spindle preferably comprises a spindle that is connected in a fixed manner to the joint ball, wherein the ruled surface is provided for example on the side of the joint ball remote from the spindle. In particular, the ruled surface forms an opposite end face or end of the ball-ended spindle to the spindle. The ruled surface is preferably aligned approximately at right angles to the longitudinal axis of the ball-ended spindle, wherein the term "approximately" takes into consideration that the ruled surface is not planar. According to a development, the joint ball is provided at approximately 2/3 of its height with a flattened portion, on which the ruled surface is formed. Prior to formation of the ruled surface the flattened portion is preferably planar and aligned at right angles to the longitudinal axis of the ball-ended spindle. The ruled surface has in particular a circumferential boundary that preferably surrounds or encircles the central longitudinal axis of the ball-ended spindle.
Between the housing and the ball-ended spindle a protective or sealing gaiter is preferably disposed, which prevents dirt and moisture from penetrating into the interior of the ball joint. The spindle of the ball-ended spindle is configured in particular as a threaded spindle.
The contact region between ruled surface and lay-on device is preferentially linear and lies in particular along a straight line. An optimum guidance of the ball-ended spindle is therefore possible as the ruled surface may in mathematical terms indeed be generated by the movement of a straight line in space. The lay-on device is preferably connected in a fixed manner to the housing and/or mounted thereon. According to a development, the lay-on device is configured as a pin mounted in the

housing. The convex surface of the lay-on device is preferably in contact with the ruled surface along a straight line or convex surface straight line. The lay-on device is mounted in particular rotatably on the housing, thereby allowing a reduction of the friction. The rotatable mounting may be effected for example by means of at least one needle bearing bush. The lay-on device is moreover mounted in particular rotatably about its longitudinal axis on the housing.
According to a development the ball joint comprises an interlocking mechanism, by means of which the ball-ended spindle is interlocked or may be interlocked in end positions of its path of motion. In particular the joint ball comprises for this purpose at least one transverse bore, in which at least one detent ball is movably guided, which engages or may engage into a detent recess provided in the housing. If the detent ball engages into the detent recess, then the joint ball is interlocked on the housing. The detent ball is preferably preloaded by means of a spring, in particular in the direction of housing or detent recess, so that a latching occurs automatically upon reaching the end position.
According to a development, in the ball-ended spindle a longitudinal bore preferentially aligned obliquely or at right angles to the transverse bore is provided, in which an interlock deactivation pin that presses or may press the detent ball into the detent recess is spring-mounted. By moving the interlock deactivation pin counter to the spring action, the preloading of the detent ball in the direction of the detent recess may be cancelled, so that the joint ball is released and the ball-ended spindle may be moved out of the end position.
The restricted guidance of the ball-ended spindle is therefore achieved, not by means of grooves in the ball surface of the joint ball, but according to the invention by means of a ruled surface that is provided in particular on the ball end face remote from the spindle. In a preferred manner the polar side of the ball is flattened at ca. 2/3 of the ball height, wherein on this flattened portion the ruled surface is formed. The ruled surface forces the ball-ended spindle to slew laterally as it rotates. As a

mating side and/or lay-on device for the ruled surface it is possible to use a pin that is mounted in the housing and has only one of its convex surface straight lines in contact with the joint ball. Thus, in particular a slewing of the joint ball at right angles to the pin axis is prevented. To reduce the friction, the pin may further be mounted by needle bearing bushes in the housing. An oval housing opening preferably undertakes a second or additional guidance of the ball-ended spindle.
According to a development, the ball joint may be supplemented by an interlocking mechanism so that the ball-ended spindle may be locked in end positions of its path of wobbling motion. This is possible for example by means of transverse bores in the joint ball, into which are introduced small detent balls that are preloaded radially by means of a spring-loaded interlock deactivation pin, which is seated in a longitudinal bore in the ball-ended spindle that extends along the centre line of the ball-ended spindle and in particular is aligned at right angles to the transverse bores. When the detent ball centre is situated between the surface of the joint ball and the housing inner surface, the ball-ended spindle is interlocked. To deactivate the interlock of the ball-ended spindle, the interlock deactivation pin may be moved counter to the spring action into a release position, for example by means of a button, a cable pull, an electric motor, a hydraulic cylinder and/or a pneumatic cylinder.
The invention further relates to the use of a ball joint according to the invention to execute a motion, in particular a wobbling motion, of a vehicle part relative to the vehicle body of a vehicle.
There now follows a description of a preferred embodiment of the invention with reference to the drawings. The drawings show:
Fig. 1: a perspective and part-sectional representation of a ball joint according
to an embodiment of the invention,

Fig. 2: a sectional view of the ball joint in a 0° position of the ball-ended
spindle,
Fig. 3: a sectional view of the ball joint in a 30° position of the ball-ended
spindle,
Fig. 4: a sectional view of the ball joint in a 60° position of the ball-ended
spindle,
Fig. 5: a sectional view of the ball joint in a 90° position of the ball-ended
spindle,
Fig. 6: a sectional view of the ball joint in a 120° position of the ball-ended
spindle,
Fig. 7: a sectional view of the ball joint in a 150° position of the ball-ended
spindle and
Fig. 8: a sectional view of the ball joint in a 180° position of the ball-ended
spindle.
Fig. 1 shows a partially cut-open, perspective representation of a ball joint 1 according to an embodiment of the invention, wherein a ball-ended spindle 3 provided with a joint ball 2 is mounted by its joint ball 2 in a rotatable and slewable manner in a ball joint housing 4. On the housing 4 a flange 5 is provided, by means of which the housing 4 may be fastened to a vehicle part. The ball-ended spindle may further be fastened to a vehicle body so that the vehicle part may be moved relative to the body.
The ball-ended spindle 3 comprises a threaded spindle 6 connected in a fixed manner to the joint ball 2 and extends out of the housing 4. Provided on the joint

ball 2 on its side remote from the spindle 6 is a ruled surface 7, which forms an end face of the ball-ended spindle 3. The ruled surface is not planar and lies on a restricted guidance pin 8, which is situated in a bore 22 provided in the housing 4 and is mounted by means of needle bearing bushes 9 rotatably about its longitudinal axis on the housing 4. The ball-ended spindle 3 is mounted in a conventional manner with the interposition of a ball socket 10 in an inner space 11 of the housing 4 that is accessible via an oval spindle opening 12, through which the ball-ended spindle 3 extends. The housing 4 comprises a locking ring 19, in which the housing opening 12 is provided. The ball-ended spindle 3 is guided by the interaction of ruled surface 7 and pin 8, on the one hand, and by the oval housing opening 12, on the other hand, in such a restricted manner that it may move relative to the housing 4 only along a predefined path of motion that brings about a wobbling motion of the ball-ended spindle.
The ball-ended spindle 3 may be latched in specific positions on the housing 4, for which purpose there is provided an interlocking mechanism that comprises a plurality of detent balls 14, which are disposed in transverse bores 13 provided in the interior of the joint ball 2 and which may move along the transverse bores 13 and engage into detent recesses 15 provided in the inner wall of the housing 4 that delimits the inner space 11. In this case, the ball-ended spindle 3 is latched to the housing 4 when the detent balls 14 engage into the detent recesses 15. The detent balls 14 are pressed radially outwards in the direction of detent recesses 15 by means of an interlock deactivation pin 16, wherein the interlock deactivation pin 16 is guided displaceably in a longitudinal bore 17 provided in the ball-ended spindle 3 and is preloaded axially in the direction of joint ball 2 by means of a spring 18. In the non-actuated state, the interlock deactivation pin 16 therefore presses the detent ball 14 radially outwards in the direction of the housing inner wall. To deactivate the interlock of the ball-ended spindle 3, the interlock deactivation pin 16 may be moved counter to the action of the spring 18 axially away from the joint ball 2, so that the detent balls 14 may move along the transverse bores 13 into the interior of the ball-ended spindle 3 and hence cancel the interlock. The interlock-deactivated state is

evident from Fig, 1. At the location of the detent recesses 15 the ball socket 10 has holes, through which the detent balls 14 may engage into the detent recesses 15.
Figs. 2 to 8 show sectional views of the ball joint 1, wherein the interlock mechanism has been omitted for the sake of clarity. In Figs. 2 to 8 the ball-ended spindle 3 is represented in different positions of its path of motion, wherein in Fig. 2 the ball-ended spindle 3 is rotated through an angle of 0° about its longitudinal axis 20 relative to the housing 4. As the longitudinal axis 20 of the ball-ended spindle 3 in Fig. 2 coincides, at least approximately, with the longitudinal axis 21 of the housing 4 or joint 1, only the longitudinal axis 21 is represented. The same applies to Fig. 8. In Fig. 3 the angle of rotation, through which the ball-ended spindle 3 is rotated about its longitudinal axis 20, is 30°, in Fig. 4 60°, in Fig. 5 90°, in Fig. 6 120°, in Fig. 7 150° and in Fig. 8 180°. Thus, according to Figs. 2 to 8 the ball-ended spindle 3 rotates about its longitudinal axis 20 in increments of 30°. In this case, it may be seen that the ball-ended spindle 3 in Figs. 3 to 7 is laterally deflected, wherein the deflection is described by the angle between the two longitudinal axes 20 and 21. Because of the interaction of ruled surface 7 and pin 8 and because of the guidance by means of the spindle opening 12, the dependence between angle of rotation and deflection is predefined. The spindle opening 12 in this case defines the direction of the deflection, whilst the interaction of ruled surface 7 and pin 8 assigns a defined angle of rotation to each deflection.

List of reference characters
1 ball joint
2 joint ball
3 ball-ended spindle
4 housing
5 flange
6 threaded spindle
7 ruled surface
8 restricted guidance pin
9 needle bearing bush
10 ball socket/bearing shell
11 inner space
12 spindle opening
13 transverse bore
14 detent ball
15 detent recess
16 interlock deactivation pin
17 longitudinal bore
18 spring
19 locking ring

20 longitudinal axis of ball-ended spindle/central longitudinal axis
21 longitudinal axis of housing
22 housing bore

WE CLAIM:
1. Ball joint comprising
a housing (4) having a spindle opening (12),
a ball-ended spindle (3), which has a joint ball (2) and which is mounted
movably by means of the joint ball (2) in the housing (4) and extends through
the spindle opening (12) out of the housing (4),
characterized in that the joint ball (2) has a non-planar ruled surface (7) that is
in contact with a lay-on device (8) provided on the housing (4).
2. Ball joint according to claim 1,
characterized in that by virtue of the interaction of ruled surface (7) and lay-on device (8) a lateral deflection of the ball-ended spindle (3) is dependent upon a rotation of the ball-ended spindle (3) about its longitudinal axis (20).
3. Ball joint according to claim 1 or 2,
characterized in that the contact region between ruled surface (7) and lay-on device (8) is of a linear configuration and lies along a straight line.
4. Ball joint according to one of the preceding claims, characterized in that the ball-ended spindle (3) comprises a spindle (6) connected in a fixed manner to the joint ball (2) and the ruled surface (7) is provided on the side of the joint ball (2) remote from the spindle (6).
5. Ball joint according to one of the preceding claims,
characterized in that the ruled surface (7) is aligned approximately at right angles to the longitudinal axis (20) of the ball-ended spindle (3).
6. Ball joint according to one of the preceding claims,
characterized in that the joint ball (2) is provided at approximately 2/3 of its

height with a flattened portion on which the ruled surface (7) is formed.
7. Ball joint according to one of the preceding claims,
characterized in that the ruled surface (7) is manufactured by cold pressing.
8. Ball joint according to one of the preceding claims,
characterized in that the lay-on device (8) is configured as a pin, which is mounted in the housing (4) and the convex surface of which is in contact along a straight line with the ruled surface (7).
9. Ball joint according to claim 8,
characterized in that the pin (8) is mounted rotatably about its longitudinal axis on the housing (4).
10. Ball joint according to claim 8 or 9,
characterized in that the pin (8) is mounted by means of at least one needle bearing bush (9) rotatably on the housing (4).
11. Ball joint according to one of the preceding claims,
characterized in that an additional guide is provided, which restricts the lateral deflection scope of the ball-ended spindle (3).
12. Ball joint according to claim 11,
characterized in that the spindle opening (12) is of an oval configuration and forms the additional guide for the ball-ended spindle (3).
13. Ball joint according to one of the preceding claims,
characterized by an interlocking mechanism, by means of which the ball-ended spindle (3) is or may be interlocked in end positions of its path of motion.

14. Ball joint according to one of the preceding claims,
characterized in that the joint ball (2) has at least one transverse bore (13), in which at least one detent ball (14) that engages or may engage into a detent recess (15) in the housing (4) is movably guided.
15. Ball joint according to claim 14,
characterized in that in the ball-ended spindle (2) a longitudinal bore (17) aligned at right angles to the transverse bore (13) is provided, in which is spring-mounted an interlock deactivation pin (16) that presses or may press the detent ball (14) into the detent recess (15).
16. Ball joint according to one of claims 13 to 15,
characterized in that a deactivation of the interlock of the ball-ended spindle may be effected by means of a button, a cable pull, a pneumatic device, a hydraulic device or an electric motor.