Abstract:
An improved ball joint for use in such a motor vehicle steering or suspension system comprises a socket shell having a pair of openings; a bearing disposed in the socket shell; a first ball stud portion and a second ball stud portion disposed in the socket shell, the first ball stud portion defining a first bearing surface and the second stud portion defining a second bearing surface; and ball stud disposed between the bearing and the first and second ball stud portions, the ball stud having an inner surface seated on the first bearing surface of the first ball stud portion and the second bearing surface of the second ball stud portion.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates in general to vehicle steering or suspension systems and in particular to an improved ball joint for use in such a motor vehicle steering or suspension system. 
         [0002]    Ball joints provide an articulated connection between two relatively movable parts. Ball joints are commonly used in motor vehicle steering systems and in motor vehicle suspension systems. 
         [0003]    In a vehicle steering system, ball joints are commonly adapted to be connected to a steering arm of each of a wheel knuckle. Typically, a ball joint for a motor vehicle steering system includes a ball stud with a spherical ball end and a housing or socket member with a spherical socket. A bearing member in the socket receives the ball end and supports the ball end for rotational and pivotal movement. 
       SUMMARY OF THE INVENTION 
       [0004]    This invention relates to an improved ball joint for use in such a motor vehicle steering or suspension system. According to a preferred embodiment, the ball joint comprises a socket shell having a pair of openings; a bearing disposed in the socket shell; a first ball stud portion and a second ball stud portion disposed in the socket shell, the first ball stud portion defining a first bearing surface and the second stud portion defining a second bearing surface; and ball stud disposed between the bearing and the first and second ball stud portions, the ball stud having an inner surface seated on the first bearing surface of the first ball stud portion and the second bearing surface of the second ball stud portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a sectional view of a portion of a prior art ball joint. 
           [0006]      FIG. 2  is a sectional view of an embodiment n exploded view of the prior art ball joint illustrated in  FIG. 1 . 
           [0007]      FIG. 3  is a sectional view of an embodiment of a ball joint. 
           [0008]      FIG. 4  is an exploded view of selected components of the ball joint illustrated in  FIG. 3 . 
           [0009]      FIG. 5  is an enlarged view of a portion of the ball joint shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    Referring now to  FIGS. 1 and 2 , there is illustrated a portion of a prior art a ball joint, indicated generally at  10 . The general structure and operation of the prior art ball joint  10  is conventional in the art. Thus, only those portions of the prior art ball joint  10  which are necessary for a full understanding of this invention will be explained and illustrated in detail. As is well known in the art, the prior art ball joint  10  interconnects relatively movable vehicular parts, such as for example, a steering knuckle or steering yoke, with a control arm, steering yoke or steering knuckle. 
         [0011]    As shown in prior art  FIG. 1 , the ball joint  10  defines an axis A and includes a socket shell or housing  12 , a ball stud  14 , a first washer  16 , and a second washer  18 . The socket shell  12  is formed of a rigid material, such as for example, steel, and is centered on the axis A. The socket shell  12  has generally parallel, cylindrical inner and outer surfaces  20  and  22 , respectively. 
         [0012]    The socket shell  12  has a first end portion  24  and a second end portion  26 . The first end portion  24  of the socket shell  12  is provided with a radially inwardly extending flange  28 . As best shown in prior art  FIG. 2 , the flange  28  has a generally radially extending first surface  30  and a generally axially extending second surface  32 . The second surface  32  in the first end portion  24  of the socket shell  12  defines a first opening  34  in the socket shell  12 . 
         [0013]    The second end portion  26  of the socket shell  12  includes a radially inwardly extending “crimpable” flange  40  which has a crimped position (shown in prior art  FIG. 1 ), and an uncrimped position (shown in phantom in prior art  FIG. 2 ). In the crimped position, the flange  40  has a generally radially extending first surface  42  and an axially extending second surface  44 . In the crimped position, the second portion  44  of the flange  40  of the socket shell  12  defines a second opening  46  in the socket shell  12 . 
         [0014]    The ball stud  14  is formed from a suitable material, such as steel, and is centered on the axis A. The ball stud  14  includes a central ball portion  50 , a first or “upper” stud portion  52  and a second or “lower” stud portion  54 . The stud portions  52  and  54  extend from the central ball portion  50  in diametrically opposite directions. The central ball portion  50  has a substantially spherical outer surface  56  centered on a pivot center P. 
         [0015]    The central ball portion  50  includes a cylindrical inner surface  58  which defines a central passage  58 A through the ball stud  14 . The central passage  58 A is centered on the axis A and extends completely through the ball joint  10  from an end surface  16 A of the first washer  16 , through the central ball portion  50 , and to an end surface  18 A of the second washer  18 . 
         [0016]    The central ball portion  50  has a centerline B which extends perpendicular to the axis A. The pivot center P of the ball joint  10  is located on the axis A at the intersection of the axis A and the centerline B. The first and second stud portions  52  and  54  are centered on the axis B. 
         [0017]    As best shown in prior art  FIG. 2 , the first stud portion  52  has a cylindrical outer surface  60  and a stepped cylindrical inner surface, indicated generally at  62 . The stepped cylindrical inner surface  62  includes a cylindrical inner first surface  62 A and a cylindrical inner second surface  62 B. The cylindrical inner first surface  62 A defines a first inner diameter D 1  and the cylindrical inner second surface  62 B defines a second inner diameter D 2  which is greater than the first inner diameter D 1  so as to define a counterbore, indicated generally at C 1 , therein. The first stud portion  52  further includes a generally planar end surface  64  which is generally perpendicular to the axis A. 
         [0018]    The second stud portion  54  has a cylindrical outer surface  70  and a stepped cylindrical inner surface, indicated generally at  72 . The stepped cylindrical inner surface  72  includes a cylindrical inner first surface  72 A and a cylindrical inner second surface  72 B. The cylindrical inner first surface  72 A defines a first inner diameter D 3  and the cylindrical inner second surface  72 B defines a second inner diameter D 4  which is greater than the first inner diameter D 3  so as to define a counterbore, indicated generally at C 2 , therein. The first stud portion  54  further includes a generally planar end surface  74  which is generally perpendicular to the axis A. 
         [0019]    The first washer  16  is generally annular and is formed from a suitable material, such as for example metal. The first washer  16  includes a first portion  80  and a second portion  82  and has a cylindrical inner surface  84 . The first portion  80  is an enlarged diameter flanged portion which has an outer cylindrical surface  80 A. The flanged first portion  80  is adapted to be connected to a suitable vehicle suspension component, such as for example a knuckle or yoke of a suspension component, in a known manner. 
         [0020]    The outer cylindrical surface  80 A defines a first outer diameter D 5  of the first washer  16 . The second portion  82  has an outer cylindrical surface  82 A which defines a second outer diameter D 6  of the first washer  16  and which is less than the first outer diameter D 5  so as to define a lip, indicated generally at L 1 . The first washer  16  further includes an axially extending surface or shoulder  86  which extends generally perpendicular to the axis A. In the prior art ball joint  10 , the outer diameter D 6  of the second portion  82  of the first washer  16  is slightly greater than the inner diameter D 2  of the first stud portion  52  so that the lip L 1  of the first washer  16  is received in the counterbore C 1  of the first stud portion  52  in an interference or friction fit therewith. 
         [0021]    The second washer  18  is generally annular and is formed from a suitable material, such as for example metal. The second washer  18  includes a first portion  90  and a second portion  92  and has a cylindrical inner surface  94 . The first portion  90  is an enlarged diameter flanged portion which has an outer cylindrical surface  90 A. The flanged first portion  90  is adapted to be connected to a suitable vehicle suspension component, such as for example a knuckle or yoke of a suspension component, in a known manner. 
         [0022]    The outer cylindrical surface  90 A defines a first outer diameter D 7  of the second washer  18 . The second portion  92  has an outer cylindrical surface  92 A which defines a second outer diameter D 8  of the second washer  18  and which is less than the first outer diameter D 7  so as to define a lip, indicated generally at L 2 . The second washer  18  further includes an axially extending surface or shoulder  96  which extends generally perpendicular to the axis A. In the prior art ball joint  10 , the outer diameter D 8  of the second portion  94  of the second washer  18  is slightly greater than the inner diameter D 4  of the second stud portion  54  so that the lip L 2  of the second washer  18  is received in the counterbore C 2  of the second stud portion  54  in an interference or friction fit therewith. 
         [0023]    The prior art ball joint  10  further include first and second bearings  98  and  100 , respectively, for supporting the central ball portion  50  of the ball stud  14  in the housing  12  for movement relative to the housing  12 . The bearings  98  and  100  may be made of any suitable material, but typically are made of injection molded Delrin brand plastic which is available from E. I. DuPont de Nemours &amp; Co. The bearings  98  and  100  are generally annular bearings and are centered on the axis A. 
         [0024]    The first or “upper” bearing  98  has first and second end portions  102  and  104 , respectively. The first bearing  98  includes a cylindrical outer surface  98 A and a generally semi-spherical inner surface  98 B which extend between the end portions  102  and  104 . The first end portion  102  has a generally radially extending surface  102 A that extends generally perpendicular to the axis A. 
         [0025]    The second or “lower” bearing  100  has first and second end portions  106  and  108 . The bearing  100  includes a cylindrical outer surface  100 A and a generally semi-spherical inner surface  100 B which extend between the end portions  106  and  108 . The first end portion  106  has a generally radially extending surface  106 A that extends generally perpendicular to the axis A. 
         [0026]    The ball joint  10  includes first and second seals  110  and  112  for closing and sealing the first and second openings  34  and  46 , respectively, in the socket shell  12 . The first and second seals  110  and  112  are annular and are centered on the axis A. The seals  110  and  112  are preferably made of a suitable elastomeric material, but may be made of other suitable materials known in the art. 
         [0027]    The first seal  110  includes a stud seal portion  120  and a bearing seal portion  122  which are connected by a connector portion  124 . The stud seal portion  120  includes an axially extending surface  126  which defines a passage for receiving the first stud portion  52  of the ball stud  14 . An S-shaped spring ring (not shown) is typically injection molded in the stud seal portion  120  of the first seal  110  and is embedded in the stud seal portion  120 . The spring ring exerts a radially inward biasing force on the stud seal portion  120  of the first seal  110 . 
         [0028]    The first seal  110  typically includes an annular metal retaining ring (not shown) which is injection molded in the bearing seal portion  122  of the first seal  110 . The retaining ring is generally square in cross-section and is surrounded on all four sides by the elastomeric material of the bearing seal portion  122 . 
         [0029]    The second seal  112  includes a stud seal portion  150  and a bearing seal portion  152  which are connected by a connector portion  154 . The stud seal portion  150  includes an axially extending surface  156  which defines a passage or receiving the second stud portion  54  of the ball stud  14 . An S-shaped spring ring (not shown) is typically injection molded in the stud seal portion  150  of the second seal  112  and is embedded in the stud seal portion  150 . The spring ring exerts a radially inward biasing force on the stud seal portion  150  of the second seal  112 . 
         [0030]    The second seal  112  typically includes an annular metal retaining ring (not shown) which is injection molded in the bearing seal portion  152  of the second seal  112 . The retaining ring is generally square in cross-section and is surrounded on all four sides by the elastomeric material of the bearing seal portion  152 . 
         [0031]    In the assembled and installed condition of the prior art ball joint  10 , the socket shell  12  is installed in an opening provided in a suitable suspension component (not shown) in a well know manner. The socket shell  12  may be fixedly secured to the suspension component by press-fitting and/or welding the socket shell  12  in the opening of the suspension component. The socket shell  12  may be secured to the suspension component prior to assembly of the other components of the prior art ball joint  10  or as part of a complete ball joint assembly. The structure and operation of the prior art ball joint  10  thus far described is conventional in the art. 
         [0032]    Turning now to  FIGS. 3 and 4 , and using like reference numbers to indicate corresponding parts, there is illustrated a preferred embodiment of a ball joint, indicated generally at  200 . Although this invention will be described and illustrated in connection with the particular type of prior art ball joint disclosed herein, it will be appreciated that this invention may be used in connection with: other types of ball joints. 
         [0033]    In the illustrated preferred embodiment, the ball joint  200  includes a first or “upper” stud or washer portion  202 , a second or “lower” stud or washer portion  204 , and a ball stud  206 . In the illustrated embodiment, the first stud portion  202  is preferably formed from metal by may be formed from other suitable materials if so desired. The first stud portion  202  includes a first or “inner” portion  210 , a second or “intermediate” portion  212  and a third or “outer” portion  214 . The first stud portion  202  has an inner surface  216  and an outer surface  218 . 
         [0034]    In the illustrated embodiment, the inner surface  216  is preferably a constant cylindrical inner surface throughout its entire length from a first or “outer” end  202 A of the first stud portion  202  to a second or “inner” end  202 B of the first stud portion  202 . In the illustrated embodiment, the outer surface  218  is stepped and includes a first cylindrical outer “bearing” surface  210 A defined generally in the first portion  210 , a second rounded or radiused outer surface  220  extending outwardly from the surface  210 A, a third cylindrical outer surface  212 A defined generally in the second portion  212 , a fourth tapered outer surface  222  extending outwardly from the surface  212 A, and a fifth cylindrical outer surface  214 A defined generally in the third portion  214 . 
         [0035]    The first cylindrical outer surface  210 A defines a first outer diameter D 10  and extends an axial distance A 1 . The third cylindrical outer surface  212 A defines a second outer diameter D 11 , and the fifth cylindrical outer surface  214 A defines a third outer diameter D 12 . In the illustrated embodiment, the third outer diameter D 12  is greater than the second outer diameter D 11 , and the second outer diameter D 12  is greater than the first outer diameter D 10 . Alternatively, the construction of the first stud portion  202  may be other than illustrated if so desired. 
         [0036]    In the illustrated embodiment, the second stud portion  204  is preferably formed from metal by may be formed from other suitable materials is so desired. The second stud portion  204  includes a first or “inner” portion  230 , a second or “intermediate” portion  232  and a third or “outer” portion  234 . The second stud portion  204  has an inner surface  236  and an outer surface  238 . 
         [0037]    In the illustrated embodiment, the inner surface  226  is preferably a constant cylindrical inner surface throughout its entire length from a first or “outer” end  204 A of the second stud portion  204  to a second or “inner” end  204 B of the second stud portion  204 . As best shown in the illustrated embodiment in  FIG. 5 , the inner end  202 B of the first stud portion  202  is preferably slightly spaced apart from contacts with the inner end  204 B of the second stud portion  204 . Alternatively, there may be partial or full contact between the inner end  202 B of the first stud portion  202  and the inner end  204 B of the second stud portion  204  if so desired. 
         [0038]    In the illustrated embodiment, the outer surface  238  is stepped and includes a first cylindrical outer “bearing” surface  230 A defined generally in the first portion  230 , a second rounded or radiused outer surface  240  extending outwardly from the surface  230 A, a third cylindrical outer surface  232 A defined generally in the second portion  232 , a fourth tapered outer surface  242  extending outwardly from the surface  213 A, and a fifth cylindrical outer surface  234 A defined generally in the third portion  234 . 
         [0039]    The first cylindrical outer surface  230 A defines a first outer diameter D 13  and extends an axial distance A 2 . The third cylindrical outer surface  232 A defines a second outer diameter D 14 , and the fifth cylindrical outer surface  234 A defines a third outer diameter D 15 . In the illustrated embodiment, the third outer diameter D 15  is greater than the second outer diameter D 14  and the second outer diameter D 14  is greater than the first outer diameter D 13 . Alternatively, the construction of one or both of the first stud portion  202  and the second stud portion  204  may be other than illustrated if so desired. For example, one or both of the stud portions  202  and  204  may have threaded ends such as shown in U.S. Pat. No. 5,931,597 to Urbach, the disclosure of this patent incorporated by reference in entirety herein. Also, in the illustrated embodiment, the construction of the ball stud portions  202  and  204  are shown as being identical to each other; however, the construction of the ball stud portions  202  and  204  may be different from one another if so desired. Also, the construction of one or both of the ball stud portions  202  and  204  may be other than illustrated if so desired. 
         [0040]    The ball stud  206  is formed from a suitable material, such as for example steel, and includes an inner surface  250 , and outer surface  252 , a first end  254  and a second end  256 . The inner surface  250  is preferably a constant cylindrical inner surface throughout its entire length from the first end  254  to the second end  256 . The inner surface  250  defines an inner diameter D 16  of the ball stud  206 . The outer surface  252  is a substantially spherical outer surface and is centered on the pivot center P. Preferably, in the illustrated embodiment, the inner diameter D 16  of the ball stud  206  is generally equal to or slightly less than the outer diameters D 10  and D 13  of the respective first portions  210  and  230  of the stud portions  202  and  204  so as to be disposed therein in a press or interference fit therewith. 
         [0041]    In the illustrated embodiment, the first end  254  has a generally radially extending end surface  254 A and the second end  256  has a generally radially extending end surface  256 A. The end surface  254 A and the end surface  256 A are separated apart by one another by an axial distance A 3 . Preferably, in the illustrated embodiment, the axial distance A 3  is slightly greater than the sum of the axial distances A 1  and A 2  of the respective first portions  210  and  230  of the stud portions  202  and  204 . Also, as best shown in the illustrated embodiment in  FIG. 5 , the first end  254  is provided with a tapered portion  254 B and the second end  256  is provided with a tapered portion  256 B. Alternatively, the construction of the ball stud  206  may be other than illustrated if so desired. 
         [0042]    In the illustrated embodiment, in order to ensure that the first portion  202 , the second portion  204  and the ball stud  206 , which are preferably secured together by a friction or interference fit therewith, remain secured to each other during shipment and prior to assembly, suitable means are preferably provided. In the illustrated embodiment, an adhesive  260  (shown in  FIG. 5 ), is preferably utilized. In the illustrated embodiment, the adhesive  260  may be applied to the outer surfaces  210 A and  230 A of the first portions  210  and  230  of the stud portions  202  and  204  prior to assembling the ball stud  206  onto the stud portions  202  and  204 . Any suitable adhesive  260  may be used, such as for example urethane, silicone, or thermal-setting adhesives. Alternatively, any other suitable adhesives may be used. Also, the adhesive  260  may not be used if so desired. 
         [0043]    Also, in combination with or in place of using an adhesive, other suitable means may be used to the ensure that the first portion  202 , the second portion  204  and the ball stud  206 , which are preferably secured together by an friction or interference fit, remain secured to each other during shipment and prior to assembly. For example, the ball stud portions  202  and  204  may themselves have a construction or configuration which provides a sufficient interference fit or mechanical connection with each other, such as for example, a male portion(s) on one of the ball stud portions which is received in a female portion(s) provided on the other one of the ball stud portions or one of the ball stud portions may be provided with external threads which are threadably disposed in internal threads provided on the other one of the ball stud portions. Also, a band or other suitable retainer (not shown) may be installed around the ends  202 A and  204 A of the stud portions  202  and  204 , respectively, during shipment and prior to assembly. Such a band or retainer may be temporary or permanent depending upon its design. 
         [0044]    One possible or potential advantage of the embodiment of the ball joint  200  is that the ball stud  206  may be manufactured by production processes adopted for regular ball bearings, and the stud portions  202  and  204  may be cold formed and machined. The prior art ball stud  14  and washers  14  and  16  had an interference fit which used machining to tight tolerances. As result of this, the ball joint  200  may result in a reduction in manufacturing costs. 
         [0045]    In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its various embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.