Abstract:
A ball joint comprising a housing ( 4 ) having a pin opening ( 12 ), a ball pin ( 3 ) having a joint ball ( 2 ), the ball pin being movably supported in the housing ( 4 ) by the joint ball ( 2 ). The ball pin extends out through the pin opening ( 12 ) of the housing ( 4 ) and the joint ball ( 2 ) has a non-planar control surface ( 7 ) which is in contact with an abutment ( 8 ) provided on the housing ( 4 ).

Description:
[0001]    This application is a National Stage completion of PCT/DE2009/050029 filed May 27, 2009, which claims priority from German patent application Ser. No. 10 2008 002 207.1 filed Jun. 4, 2008. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a ball joint comprising a housing having a pin opening, and a ball pin having a joint ball, where the ball pin is movably supported in the housing by means of the joint ball and extends through the pin opening out of the housing. 
       BACKGROUND OF THE INVENTION 
       [0003]    Frequently there is a need for a joint with which a tumbling motion is attainable, in particular, a spatial tumbling track with only one degree of freedom. For this purpose, a ball joint is suitable with its three degrees of freedom, two of which, however, must be cancelled in a targeted manner. To attain a tumbling motion, a ball joint can, for example, be used in whose joint ball surface two independent grooves are provided, in which two stationary guide pins or rollers engage that are supported at the joint housing. When movement occurs, these force the ball joint onto a predefined track so that it is possible to subject a part connected to the ball joint to a desired spatial movement. 
         [0004]    The solution is, however, very costly because it is expensive to form the grooves by milling and if necessary grinding, and also to produce and assemble the guide finger. Furthermore, the double forced guidance requires high manufacturing tolerances. 
       SUMMARY OF THE INVENTION 
       [0005]    Starting from this background, the object of the invention is to create a possibility for forced guidance of a ball pin of a ball joint that is cost-effective, particularly with respect to mass production. 
         [0006]    The ball joint according to the invention, in particular for a vehicle, has a housing provided with a pin opening and a ball pin comprising a joint ball, where the ball pin is movable by means of the joint ball, especially in a rotational and pivotable manner, is supported in the housing, and extends through the pin opening and out of the housing, wherein the joint ball has a non-planar control surface which is in contact with an abutment provided at the housing. 
         [0007]    Forced guidance of the ball pin is attained from the interaction of the control surface and the abutment causing a limitation to the freedom of movement of the ball pin. Preferably, the shape of the control surface defines a spatial trajectory along which the ball pin moves or can move when the ball pin rotates or is rotated about its longitudinal axis. By means of the shape of the control surface, a dependency is created, in particular between a rotation of the ball pin about its longitudinal axis and a lateral displacement of the ball pin about at least one other axis (pivot axis) that is aligned obliquely or perpendicularly to the longitudinal axis of the ball pin. Preferably, at least one pivot axis intersects the longitudinal axis of the ball joint, wherein the intersection point preferably lies in the center of the joint ball. The interaction of the control surface and the abutment forces especially the joint pin to laterally deflect while rotating about its longitudinal axis. The control surface is produced, for example, through cold pressing, which can be very cost-effective in large quantities. In particular, a control surface is mathematically understood to be a surface that can be created by movement of a line in space (see I. N. Bronstein and K. A. Semendjajew, Taschenbuch der Mathematik [Handbook of Mathmatics], 25 th  edition 1991, B. G. Teubner Verlagsgesellschaft, Stuttgart, pg. 605). 
         [0008]    A supplementary limitation of the freedom of movement of the ball pin, or supplementary forced guidance of the ball pin, can result through an additional guidance by means of which the ball pin is guided and in particular forced along a predefined trajectory. The additional guidance limits, in particular, the possible lateral deflections of the ball pin and can, for example, be formed by a slotted link through which the ball pin extends. The additional guidance is preferably formed by the pin opening. The additional guidance or pin opening is preferably oblong and in particular oval, which can be implemented relatively cost-effectively. The possible movements of the ball pin are preferably limited to a spatial trajectory, in particular for implementing a tumbling movement, by the pin opening and the interaction of the control surface and the abutment. 
         [0009]    The ball pin preferably has a pin firmly connected to the joint ball, where the control surface, is for example, provided on the side of the joint ball facing away from the pin. In particular, the control surface forms a face surface or a face side of the ball pin opposite the pin. Preferably, the control surface is aligned approximately perpendicularly to the longitudinal axis of the ball pin, where the term “approximately” takes into account that the control surface is not planar. According to one embodiment, the joint ball has a flattening at approximately ⅔ of its height, at which the control surface is formed. Before the formation of the control surface, the flattening is preferably planar and aligned perpendicularly to the longitudinal axis of the ball pin. The control surface has, in particular, a circumferential boundary which preferably encompasses or surrounds the central longitudinal axis of the ball pin. 
         [0010]    A protection bellows or bellows seal is preferably disposed between the housing and the ball pin, preventing the penetration of contaminants and moisture into the interior of the ball joint. The pin of the ball pin is formed in particular as a threaded pin. 
         [0011]    The contact area between the control surface and the abutment is preferably linear and in particular lies on a straight line. Optimal guidance of the ball pin is thereby possible because, from the mathematical point of view, the control surface can be created by the movement of a straight line in space. The abutment is preferably solidly attached to the housing and/or supported thereon. According to a further development, the abutment is formed as a guide pin supported in the housing. The peripheral surface of the abutment is preferably in contact with the control surface along a straight line or a straight line of the peripheral surface. The abutment is preferably supported at the housing in a rotatable manner, so that friction can be reduced. The rotatable support can be provided, for example, by means of at least one needle bearing bushing. Furthermore, the abutment is supported at the housing, in particular, in a rotational manner about its longitudinal axis. 
         [0012]    According to one embodiment, the ball joint has a locking mechanism by means of which the ball pin is locked, or can be locked, in end positions of its trajectory. In particular, the joint ball has a least one transverse bore for this purpose in which at least one detent ball is movably guided that engages or can engage in a latch recess provided in the housing. If the detent ball engages in the latch recess, the joint ball is locked at the housing. The detent ball is preferably pre-tensioned by means of a spring, in particular in the direction of the housing or latch recess, so that locking occurs automatically upon attaining the end position. 
         [0013]    According to a further development, a longitudinal bore is provided in the ball pin and is preferably aligned obliquely or perpendicularly to the transverse bore, and an unlocking pin spring-mounted in the longitudinal bore presses or can press the detent ball into the latch recess. Due to the movement of the unlocking pin against the spring force, the pretension of the detent ball in the direction of the latch recess can be cancelled so that the joint ball is released, and the ball pin can be moved out of the end position. 
         [0014]    The forced guidance of the ball pin is therefore not attained due to the grooves in the surface of the joint ball, but rather according to the invention due to a control surface that, in particular, is provided on the ball face surface opposite the pin. Preferably, the polar side of the ball is flattened at approximately ⅔ of the ball height, wherein the control surface is formed at this flattening. The control surface forces the ball pin to pivot laterally during its rotation. A guide pin can be used as an opposite side or abutment for the control surface, the guide pin being supported in the housing and contacting the ball joint with only one of the straight lines of its peripheral surface. In this manner, in particular pivoting of the joint ball perpendicular to the guide pin axis is prevented. In order to reduce friction, the guide pin can be supported in the housing using needle bearing bushings. Preferably, an oval housing opening performs a second or additional guidance of the ball pin. 
         [0015]    According to a further development, the ball joint can be supplemented by a locking mechanism so that the ball pin can be stopped in the end positions of its tumbling trajectory. This is possible, for example, by means of transverse bores in the joint ball into which small detent balls are introduced which are pre-tensioned radially by a spring-loaded unlocking pin that is located in a longitudinal bore in the ball pin, which bore runs along the central line of the ball pin and, in particular, is aligned perpendicularly to the transverse bore. When the center of the detent ball is located between the surface of the joint ball and the housing inner surface, the ball pin is locked. To unlock the ball pin, the unlocking pin can be moved counter to the spring force into a releasing position, for example, by means of a button, a Bowden cable, an electric motor, a hydraulic cylinder, and/or a pneumatic cylinder. 
         [0016]    The invention further relates to the use of a ball joint according to the invention for performing a movement, in particular a tumbling movement, of a vehicle part relative to the vehicle body of a vehicle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0017]    The invention is described below using a preferred embodiment with reference to the drawings. They show: 
           [0018]      FIG. 1 : a perspective, partial section of a ball joint according to one embodiment of the invention, 
           [0019]      FIG. 2 : a sectional view of the ball joint in a 0° position of the ball pin, 
           [0020]      FIG. 3 : a sectional view of the ball joint in a 30° position of the ball pin, 
           [0021]      FIG. 4 : a sectional view of the ball joint in a 60° position of the ball pin, 
           [0022]      FIG. 5 : a sectional view of the ball joint in a 90° position of the ball pin, 
           [0023]      FIG. 6 : a sectional view of the ball joint in a 120° position of the ball pin, 
           [0024]      FIG. 7 : a sectional view of the ball joint in a 150° position of the ball pin, and 
           [0025]      FIG. 8 : a sectional view of the ball joint in a 180° position of the ball pin. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]      FIG. 1  shows a perspective view of a partial section of a ball joint  1  according to one embodiment of the invention, where a ball pin  3  provided with a joint ball  2  is supported in a rotational and pivotable manner with its joint ball  2  in a ball joint housing  4 . The housing  4  can be fastened to a vehicle part by means of a flange  5  provided at the housing  4 . Further, the ball pin can be fastened to a vehicle chassis so that the vehicle part can be moved relative to the chassis. 
         [0027]    The ball pin  3  has a threaded pin  6  firmly connected to the joint ball  2  and extending out of the housing  4 . A control surface  7 , provided on the joint ball  2  on its side facing away from the pin  6 , forms a face surface of the ball pin  3 . The control surface is non-planar and abuts a forced guide pin  8  which is enclosed in a bore  22  provided in the housing  4  and, by means of needle bearing bushings  9 , is supported at the housing  4  and can rotate about its longitudinal axis. The ball pin  3  is supported in an internal space  11  of the housing  4  in the customary manner by interposing a ball shell  10 ; the internal space  11  is accessible via an oval shaped pin opening  12  through which the ball pin  3  extends. The housing  4  comprises a locking ring  19  in which the housing opening  12  is provided. The ball pin  3  is forcibly guided by the interaction of the control surface  7  and the guide pin  8 , and by the oval housing opening  12 , so that it can move, relative to the housing  4  only along a predefined trajectory that results in a tumbling motion of the ball pin. 
         [0028]    The ball pin  3  can be locked in specific positions in the housing  4 , for which a locking mechanism is provided that comprises several detent balls  14  disposed in the transverse bores  13  provided in the interior of the joint ball  2 , that move along the transverse bores  13  and can engage in latch recesses  15  provided in the inner wall of the housing  4  bordering the internal space  11 . The ball pin  3  is locked in the housing  4  when the detent balls  14  engage in the latch recesses  15 . The detent balls  14  are pressed by means of an unlocking pin  16  radially outward in the direction of the latch recesses  15 , wherein the unlocking pin  16  is slidably guided in an elongated bore  17  provided in the ball pin  3 , and is pretensioned axially in the direction of the joint ball  2  by means of a spring  18 . In the non-activated state, the unlocking pin  16  hence presses the detent ball  14  radially outward in the direction of the housing inner wall. To unlock the ball pin  3 , the unlocking pin  16  can be moved against the force of the spring  18  axially away from the joint ball  2  so that the detent balls  14  can move along the transverse bores  13  into the interior of the ball pin  3 , and thus can release the lock. The unlocked state can be seen in  FIG. 1 . At the location of the latch recesses  15 , the ball shell  10  has holes through which the detent balls  14  can engage in the latch recesses  15 . 
         [0029]      FIGS. 2 to 8  show sectional views of the ball joint  1 , where for clarity the locking mechanism has been omitted. In  FIGS. 2 to 8 , the ball pin  3  is shown in different positions of its trajectory, where in  FIG. 2  the ball pin  3  is rotated by an angle of 0° about its longitudinal axis  20  relative to the housing  4 . In  FIG. 2 , the longitudinal axis  20  of the ball pin  3  nearly coincides with the longitudinal axis  21  of the housing  4  or joint  1 , so that only the longitudinal axis  21  is represented. The corresponding applies for  FIG. 8 . The rotational angle by which the ball pin  3  is rotated about its longitudinal axis  20  is 30° in  FIG. 3 , 60° in  FIG. 4 , 90° in  FIG. 5 , 120° in  FIG. 6 , 150° in  FIGS. 7  and 180° in  FIG. 8 . Thus, according to  FIGS. 2 to 8 , the ball pin  3  rotates about its longitudinal axis  20  in steps of 30°. It can be seen here that the ball pin  3  in  FIGS. 3 to 7  is deflected laterally, where the deflection is described by the angle between the two longitudinal axes  20  and  21 . The dependency between the rotational angle and the deflection is fixed by the interaction of the control surface  7  and the guide pin  8 , and by the guidance by the pin opening  12 . The pin opening  12  determines the direction of deflection, whereas the interaction of the control surface  7  and the guide pin  8  assigns to each deflection a defined angle of rotation. 
       LIST OF REFERENCE CHARACTERS 
       [0000]    
       
           1  ball joint 
           2  joint ball 
           3  ball pin 
           4  housing 
           5  flange 
           6  threaded pin 
           7  control surface 
           8  forced guidance pin 
           9  needle bearing bushing 
           10  ball shell/bearing shell 
           11  internal space 
           12  pin opening 
           13  transverse bore 
           14  detent ball 
           15  latch recess 
           16  unlocking pin 
           17  elongated bore 
           18  spring 
           19  locking ring 
           20  longitudinal axis of the ball pin/central longitudinal axis 
           21  longitudinal axis of the housing 
           22  housing bore