Abstract:
A supporting joint includes a ball pin connected to a ball head that is movably mounted in an outer body having a recess, and a sliding element arranged between the ball head and the outer body. The sliding element includes a flexible, disk-shaped plain-bearing film having a plurality of plain-bearing film strips. The strips are arranged relative to each other at least approximately in a star shape. The strips are formed integrally with each other, and separated by slits. The plain-bearing film is placed between the outer body and the ball head in a cup shape such that edges of the plain-bearing film strips lie tightly against each other without overlaps and/or folds.

Description:
PRIORITY INFORMATION 
       [0001]    This patent application claims priority from PCT Application No. PCT/EP 2010/004606 filed Jul. 28, 2010 and German Application No. 10 2009 041 807.5 filed Sep. 18, 2009, each of which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to a joint and, more particularly, to a supporting joint and/or ball and socket joint with a plain bearing film. 
         [0003]    Various supporting joints and/or ball and socket joints for steering mechanisms in motor vehicles are known in the art. An example of a ball and socket joint is described in D.E. Application No. 10 2007 016 713, which includes a spherical rod end (also referred to as a ball head) and a spherical pivotal bearing. The pivotal bearing includes a multi-layer plain-bearing shell which is split in two. The plain-bearing shell includes an inner sliding layer of polytetrafluoroethylene (PTFE) that is stuck to a load-bearing layer such as, for example, a steel mesh. The steel mesh is applied to an elastic layer containing an elastomer by means of an adhesion promoting layer. Such a pivotal bearing may be operated without the addition of a lubricant and has improved absorption quality due to the application of the elastic layer. The ball head is enclosed by a total of two stable plain-bearing shell components; i.e., a lower hemispherical first plain-bearing shell component and a ring-shaped second plain-bearing shell component situated above the first plain-bearing shell component. The second plain-bearing shell component must be slid over the ball pin by assembly of the pivotal bearing, which is costly. 
         [0004]    Another example of a pivotal bearing is described in D.E. Application No. 10 2008 003 730, which includes a spherical inner body that is encompassed by two housing half shells outside. Each of the two housing half shells is furnished inside with a plain-bearing film. 
         [0005]    The pivotal bearings are manufactured as described above so that a specially designed plain-bearing film is applied to the interior of the unformed housing components with, for example, adhesive. The housing components are subsequently cold formed so that the components adapt to the surface of the spherical inner body and are converted to the housing half shells. 
       SUMMARY OF THE INVENTION 
       [0006]    The object of the present invention is to provide a supporting joint that may accommodate relatively high loads, and a relatively stiff bearing. 
         [0007]    According to an aspect of the invention, a joint is provided that includes a pin connected to a ball head that is movably mounted in an outer body having a recess, and a sliding element made from a flexible plain-bearing film arranged between the ball head and the outer body. The plain-bearing film includes a plurality of plain-bearing film strips arranged relative to each other at least approximately in a star shape. The strips are formed integrally with each other and are separated by slits. The plain-bearing film is placed between the outer body and the ball head such that edges of the plain-bearing film strips lie as tightly as possible against each other without, for example, overlaps and/or folds. 
         [0008]    The joint may be configured as a supporting joint and/or a ball joint. In some embodiments, therefore, the pin may be a ball pin, tapered pin, cylinder pin or lug. 
         [0009]    The joint may include a single, one-piece plain-bearing film. In addition, the joint may have a relatively high stiffness, and may be included in performance handling systems of motor vehicles. 
         [0010]    The joint may have a high transmittable axial and radial load capacity. The joint has a low friction coefficient, a small installation space and a light weight. The joint also has a relatively high operating temperature range. 
         [0011]    In some embodiments, the plain-bearing film is constructed from Nordglide™ M material, which is made by Saint-Gobain Performance Plastics Pampus GmbH in D-47877 Willich, Germany. Such a plain-bearing film may provide a relatively maintenance-free bearing film with a high load capacity made of a metallic mesh and hard-wearing PTFE compound. Such a plain-bearing film includes a plain-bearing material made out of a PTFE compound which is sintered to a flexible metallic mesh ridge. The PTFE compound may include thirty percent (30%) filler content, where the filler includes fiber glass and/or graphite. The metallic mesh may be a stainless steel mesh made of wire that may be connected to the intersections. Such a plain-bearing film may have a total thickness of, for example, 0.5 mm. 
         [0012]    In some embodiments, the plain-bearing film may be inserted in the joint without additional lubricant(s). In other embodiments, the joint includes a lubricant. 
         [0013]    In some embodiments, the sated plain-bearing film with its individual plain-bearing film strips fits around the ball head in a spherical shell shape more than a hemispherical shell shape. The plain-bearing film with its plain-bearing film strips may enclose the ball head—starting at the deepest point of the ball head axially—for more than half of the diameter of the ball head; e.g., up to approximately ⅔ of the diameter of the ball head. Thus, the plain-bearing film may almost completely cover the ball head to provide an optimal plain-bearing of the ball head in the outer body. The individual plain-bearing film strips duly lie next to each other as seamlessly as possible. 
         [0014]    In some embodiments, the outer body of the joint includes a housing and/or a bearing shell. An at least hemispherical recess for receiving the ball head and a ring-shaped, additional recess for receiving the ring-shaped bearing shell situated above the hemispherical recess are provided in the housing. 
         [0015]    In some embodiments, a ring-shaped lug is provided either in the outer body and/or the bearing shell, if the latter is used, as an axial limit for the plain-bearing film 
         [0016]    In some embodiments, in order to protect the supporting joint, a ring nut may be screwed to the bearing shell using a thread in the outer body and/or the housing. An axial protection of the whole supporting joint is thereby provided. 
         [0017]    In some embodiments, the slits which runs from the radial exterior to the radial interior on a center of the plain-bearing film, if the flexible plain-bearing film is stretched flat, are designed to be tapered from the outside to the inside; e.g., at least approximately triangular. As a result, it has proved favorable to curve the individual plain-bearing film strips viewed in a radial direction to the outside and then to arrange them in a tapered form. It should be ensured that, with the spherical shell-shaped coverings of the ball head, the individual plain-bearing film strips lie as close to each other as possible so that only very small gaps are left, or ideally, so that no gaps remain at all. The plain-bearing film should be substantially without folds and/or overlaps on the ball head. 
         [0018]    In some embodiments, the plain-bearing film includes a central opening having a round geometry. Such a central opening significantly eases the operation of the plain-bearing film during assembly, since a device can grip this opening and then hold the plain-bearing film in place. 
         [0019]    In some embodiments, the plain-bearing film may include a sintered compound with PTFE or a sintered PTFE compound. For this purpose, a PTFE compound is sintered to a metallic mesh ridge. With the assembly of such a plain-bearing film in the recess of the outer body, then of the housing of the supporting joint, the PTFE layer faces the ball head, while the metallic mesh points towards the housing and/or the outer body. 
         [0020]    In some embodiments, the contour of the plain-bearing film may be manufactured as a simple pressed part with individual, one-piece plain-bearing film strips facing each other, where the strips are separated from each other by slits. The special outer contour of the plain-bearing film may, however, also be separated from a continuous plain-bearing film strip in some other way, e.g. by cutting it out. 
         [0021]    In some embodiments, the plain-bearing film inserted in the joint is equipped with an upper flange that is formed by the respective free ends of the plain-bearing film strips. The flange is arranged such that it runs at the same height from the lowest point of the ball head. Thus, the upper flange of the plain-bearing film runs in a straight line when mounted. The upper flange may be fastened safely to the aforementioned lug to provide an optimal accommodation of the plain-bearing film. 
         [0022]    These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0023]    In the following diagrams, unless otherwise indicated, identical reference characters always designate identical parts with the same meaning. 
           [0024]      FIG. 1  is a cross-sectional illustration of a supporting joint with a ball pin and a ball head orientated towards a longitudinal axis of the supporting joint; 
           [0025]      FIG. 1A  is an enlarged illustration of section A of the supporting joint of  FIG. 1 ; 
           [0026]      FIG. 2  is a cross-sectional illustration of the supporting joint of  FIG. 1  with a slanted ball pin; 
           [0027]      FIG. 3  is an illustration of a plain-bearing film in a stretched-out flat configuration; 
           [0028]      FIG. 4  is an enlarged illustration of a strip B of the plain-bearing film of  FIG. 3 ; 
           [0029]      FIG. 5  is a perspective illustration of the plain-bearing film of  FIG. 3  in a curved configuration; 
           [0030]      FIG. 6  is a partial cutaway illustration of another supporting joint with a plain-bearing film; 
           [0031]      FIG. 7  is a partial cutaway illustration of still another supporting joint; 
           [0032]      FIG. 8  is a partial cutaway illustration of still another supporting joint; 
           [0033]      FIG. 9  is an illustration of another plain-bearing film in a stretched-out flat configuration; 
           [0034]      FIG. 10  a perspective illustration of the plain-bearing film of  FIG. 9  in a curved configuration; 
           [0035]      FIG. 11  is an illustration of still another plain-bearing film in a stretched-out flat configuration; and 
           [0036]      FIG. 12  is a perspective illustration of the plain-bearing film of  FIG. 11  in a curved configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]      FIG. 1  illustrates a first embodiment of a supporting joint  10 . The supporting joint  10  includes a ball pin  12 , in a lower end of which a ball head  13  is mounted. The ball pin  12  of  FIG. 1  is illustrated with the ball head  13  orientated on an X-axis of the supporting joint  10 . The ball head  13  sits in a hemispherical shell-shaped recess  15  of a housing  18 . Above the hemispherical shell-shaped recess  15  of the housing  18  is a ring-shaped bearing shell  16 . The inner diameter of the ring-shaped bearing shell  16  is adapted to the ball contour of the ball head  13 , and has a slightly larger diameter than an outer diameter of the ball head  13 . The hemispherical shell-shaped recess  15  of the housing  18  also is adapted to the ball contour of the ball head  13 , and has a slightly larger diameter than the outer diameter of the ball head  13 . 
         [0038]    A plain-bearing film  20  is arranged between the ball head  13  and the hemispherical shell-shaped recess  15  of the housing  18  and the inner wall of the ring-shaped bearing shell  16 . The plain-bearing film  20  is cup-shaped and/or partially spherically shell-shaped in the slit-shaped, spherical opening formed between the ball head  13  and the housing  18  on the one hand and between the inner wall of the ring-shaped bearing shell  16  and the ball head  13  on the other hand. 
         [0039]    Referring to  FIG. 1A , the plain-bearing film  20  substantially overlaps the lower half of the ball head  13  and adjoins a ring-shaped rotary flange and/or lug  16   a  of the ring-shaped bearing shell  16 . Referring again to  FIG. 1 , the plain-bearing film  20  overlaps approximately one half of the diameter 0.5 D of the ball head  13  and up to approximately two thirds (⅔) of the diameter D of the ball head  13 . An additional ring-shaped opening is provided in the housing  18  above the ring-shaped bearing shell  16 . The ring-shaped opening in the housing  18  has a thread  17  in which a ring nut  14  with an outer thread can be screwed. The screwing of the ring nut  14  in the housing  18  secures and braces the ring-shaped bearing shell  16  in the housing. In order to tighten the ring nut  14  in the housing  18 , a plurality of holes  14   a  are disposed in the side of the ring nut  14  facing the ball pin  12 , whereby torsion of the ring nut  14  with a suitable tool is possible. In other embodiments, slits, grooves, notches or the like may be used instead of the holes  14   a.    
         [0040]      FIG. 2  illustrates the supporting joint  10  of  FIG. 1  with a ball pin  12  slanted relative to the X-axis. 
         [0041]      FIG. 3  illustrates the plain-bearing film  20  in a stretched out flat configuration. The plain-bearing film  20  may be made from a flat material made from tape with a view to the plain-bearing film surfaces  24 . The plain-bearing film  20  includes a plain-bearing ridge  25  (see  FIG. 5 ), which is turned away from the viewer in  FIG. 3 . The plain-bearing film  20  has a central opening  23  from which a plurality of plain-bearing film strips  22  extend in a radial direction. Adjacent strips  22  are separated by respective slits  21 . A metal mesh made from a PTFE compound underlying the plain-bearing film  20 . The side of the plain-bearing film  20  that includes the metal mesh is turned away from the viewer in  FIGS. 4 and 5 . The metal mesh is arranged on the outer side of the partially spherical shell in  FIG. 5 . The plain-bearing film  20  is contoured so that whether it is cup-shaped and/or spherically shell-shaped or partially spherically shell-shaped it can be positioned optimally around the ball head  13 . An optimal application is understood to be an application of the plain-bearing film  20  on the ball head  13  that is free of overlaps and folds. The plain-bearing film strips  22  are attached to a middle, ring-shaped rotary plain-bearing film component  29 . This rotary plain-bearing film component  29  extends from the flange of the opening  23  to the beginning of each slit  21 . As illustrated in  FIG. 3 , the slits  21  extend more or less from the outer flange  26  of each plain-bearing film strip  22  approximately a quarter of the diameter in the direction of the center and/or opening  23 . The individual slits  21  have approximately triangular and taper geometries that extend from the flange  26  towards the inner opening  23 . 
         [0042]    Referring to  FIGS. 3 and 4 , the individual plain-bearing film strips  22  each have a somewhat bulbous design. A bulbous design is understood to mean that the opposing edges  27 ,  28 —originating from the opening  23 —in the center of the plain-bearing strip in  FIG. 3  curve outwardly to some extent towards the outer flange  26 . The individual plain-bearing film strips  22  in the position marked by the reference character S in  FIG. 4  therefore are broader than on the outer flange  26 , which has the width R. As additionally outlined, the flange  26  of each plain-bearing film strip  22  is perpendicular to the symmetrical line Y of each plain-bearing film strip  22 . 
         [0043]    The bulbous contour permits the individual plain-bearing film strips  22  to wrap around the ball head  13  without unnecessarily broad slits  21  remaining as illustrated in  FIG. 5 . Ideally, the plain-bearing film  20  has relatively small slits  21  or absolutely no slits when it is wrapped around the ball head  13 ; e.g., the individual plain-bearing film strips  22  may touch each other longitudinally.  FIG. 5  illustrates the upper circular rotary flange  26 , which on account of the substantially equal lengths of the individual plain-bearing film strips  22  in relation to the lowest point of the ball head  13 , is arranged at the same height when mounted correctly. The rotary flange  26  has its lug in the mounting of the plain-bearing film  20  on the ring-shaped rotary lug  16   a  of the ring-shaped bearing shell  16 . A slippage of the plain-bearing film  20  when mounted in the supporting joint  10  is therefore prevented. The plain-bearing film  20  is securely ‘accommodated’ by this lug  16   a.    
         [0044]    Although it is perfectly possible to add a lubricant to the plain-bearing film  20 , it is not necessary. A lubricant-free supporting joint, for example, is presentable with such a contoured plain-bearing film  20 . 
         [0045]    Additional embodiments of a supporting joint  10  are illustrated in  FIGS. 7 to 9 . All of these embodiments may include a plain-bearing film  20  as illustrated, for example, in  FIGS. 4 to 6 . 
         [0046]      FIG. 6  illustrates the ball pin  12  with a ball head  13  mounted below along the X-axis with half of the represented top view and half of the sectional view. The plain-bearing film  20  is located in turn between the housing  18  and the ball head  13 . The upper rotary part of the plain-bearing film  20  is, as illustrated in  FIG. 1 , located in the ring-shaped bearing shell  16 , which is secured from above by a ring nut  14  screwed in the housing  18 . Contrary to the embodiment of  FIG. 1 , the housing  18  is situated in an outer part  19 . In addition, the supporting joint  10  is caulked with a sealing gasket  40 . The sealing gasket  40  overlaps the lower part of the pin  12  and is secured by a first clamping ring  42 . The sealing gasket  40  is attached to the housing  18  by the end facing the ball head  13 , for example, by vulcanization or by clamping in a corresponding groove of the housing  18 . 
         [0047]    Referring to  FIG. 7 , the ball head  13  is in a bearing shell  46  that includes a hemispherical opening for receiving the ball head  13 . The bearing shell  46  is surrounded by a housing  45 . The housing  45  has a ring-shaped inner wall that overlaps the upper part of the ball head  13  in a similar manner to the bearing shell  16  of  FIG. 6 . An inner contour, for example, is adapted to the ball head  13 . The housing  45  which, similarly to the bearing shell  16  of  FIG. 6 , has a ring-shaped rotary lug  45   a  for the axial security of the plain-bearing film  20 . 
         [0048]    The housing  45  is mounted in an outer part  50  and secured axially with a locking ring  47 . The bearing shell  46  is on a nut  53 . An O-ring  52  may be placed between the nut  53  and the bearing shell  46 . 
         [0049]    The supporting joint in  FIG. 7  likewise includes a sealing gasket  40 , which is fastened to the ball pin  12  by a first clamping ring  42  above and by a second clamping ring  43  below. 
         [0050]    The outer part  60  of the bearing shell  62  of  FIG. 8 , in contrast to the outer part  50  of  FIG. 7 , overlaps the ball head  13 . The plain-bearing film  20  protrudes into the recess of the bearing shell  62 , and overlaps the bearing shell  62  so that the upper end of the plain-bearing film  20  lies between the outer part  60  and the ball head  13 . The lug is affected by a ring-shaped lug  60   a  on the outer part  60  for the axial security of the plain-bearing film  20 . 
         [0051]    Although the plain-bearing film  20  was represented in connection with  FIGS. 3 to 5 , other plain-bearing film configurations may also be used where a plurality of plain-bearing film strips  22  extend to a ring-shaped rotary middle plain-bearing film component  29 . Preferably, the plain-bearing film  20  should include at least three plain-bearing film strips  22 ; e.g., between five and twelve plain-bearing film strips. 
         [0052]      FIGS. 9 and 10  illustrate an alternate embodiment plain-bearing film  20  that includes six plain-bearing film strips  22 . The plain-bearing film strips  22  extend in a star shape from the middle opening  23 . The slits  21  extend respectively between the individual plain-bearing film strips  22 . The reference characters already used in  FIGS. 3 to 5  are used again for this embodiment of the plain-bearing film  20 . The edges  27 ,  28  are also arranged originating parallel to each other in this embodiment. 
         [0053]      FIGS. 11 and 12  illustrate another alternate embodiment plain-bearing film including a plurality of individual plain-bearing film strips  122 . The individual plain-bearing film strips  122  are separated by respective slits  21 . The plain-bearing film strips  122  extend in a star-shaped manner and have substantially non-parallel edges  27 ,  28 . The individual plain-bearing film strips  122 , for example, are formed by honeycombed sections  122   a  strung together. The individual sections  122   a  may join together optimally with the enclosure of the ball head of a joint so that there are no slits, or almost no slits. The advantage of such an arrangement is that an even better enclosure of the ball head of a joint can be achieved. 
         [0054]      FIG. 12  illustrates a curved version of the strung-together honeycombed sections  122   a  of the individual plain-bearing film strips  122 , in which a partially spherical shell is formed. 
         [0055]    Although the present invention has been illustrated and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the faun and detail thereof, may be made therein, without departing from the spirit and scope of the invention.