Abstract:
An improved ball joint for use in a motor vehicle steering or suspension system includes a housing, a bearing disposed in the housing, and a ball stud supported within the housing by the bearing. The bearing includes at least a first bearing member formed from a first material and a second bearing member formed from a second dampening material attached to at least a portion of an outer surface of the first bearing member. The first bearing member has a bidirectional slot formed therein which is configured to allow the ball stud to articulate in a first direction and restrict and dampen articulation in a second direction which is generally transverse to the first direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Background of the Invention 
     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. 
     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. 
     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. Such a steering system having a ball joint is disclosed in U.S. Pat. No. 7,261,487 B2 to Urbach, the disclosure of this patent incorporated by reference herein in entirety. 
     SUMMARY OF THE INVENTION 
     This invention relates to an improved ball joint for use in such a motor vehicle steering or suspension system. 
     According to one embodiment, the ball joint comprises: a housing; a bearing disposed in the housing; and a ball stud supported within the housing by the bearing; wherein the bearing includes at least a first bearing member formed from a first material and a second bearing member formed from a second dampening material attached to at least a portion of an outer surface of the first bearing member, the first bearing member having a bidirectional slot formed therein which is configured to allow the ball stud to articulate in a first direction and restrict and dampen articulation in a second direction which is generally transverse to the first direction. 
     According to this embodiment of the ball joint, the bidirectional slot includes a first slot portion having a first shape and a second slot portion having a second shape different from the first shape. 
     According to this embodiment of the ball joint, the first shape of the first slot portion is generally oval-shaped and the second shape of the second slot portion is generally concave shaped. 
     According to this embodiment of the ball joint, the first slot portion is generally in the center of the bearing and the second slot portion is formed by a pair of generally concave shaped slots disposed on opposed sides of the first slot portion. 
     According to this embodiment of the ball joint, the bearing includes an opened first end having a first opening formed therein and an opposite opened second end having a second opening formed therein which is different from the first opening. 
     According to this embodiment of the ball joint, the ball stud includes a ball portion and a pin portion, wherein the pin portion is disposed in the first slot portion and the ball portion is disposed in the second slot portion. 
     According to this embodiment of the ball joint, the second bearing member is secured to substantially the entire outer surface of the first bearing member. 
     According to this embodiment of the ball joint, the first bearing member is formed from one of metal or plastic and the second bearing member is formed from one of rubber or plastic. 
     According to this embodiment of the ball joint, the second direction defines a minor axis of the ball joint such that when the ball joint is impacted with loads in the direction of the minor axis the first bearing member partially unseats from a portion of a housing internal counterbore whereby the second member is operative to dampen the loads into the ball joint. 
     According to another embodiment, a ball joint comprises: a housing having a chamber; a bearing disposed in the chamber of the housing; and a ball stud supported within the chamber of the housing by the bearing; wherein the bearing includes a first bearing member formed from a first material and a second bearing member formed from a second dampening material and attached to at least a portion of an outer surface of the first bearing member, the first bearing having a first slot portion and a second slot portion formed therein, wherein the first slot portion is configured to allow the ball stud to articulate in a first direction and the second slot portion is configured to restrict and dampen articulation in a second direction which is generally transverse to the first direction. 
     According to this embodiment of the ball joint, the first slot portion has a first shape and a second slot portion has a second shape different from the first shape. 
     According to this embodiment of the ball joint, the first shape of the first slot portion is generally oval-shaped and the second shape of the second slot portion is generally concave shaped. 
     According to this embodiment of the ball joint, the first slot portion is generally in the center of the bearing and the second slot portion is formed by a pair of generally concave shaped slots disposed on opposed sides of the first slot portion. 
     According to this embodiment of the ball joint, the bearing includes an opened first end having a first opening formed therein and an opposite opened second end having a second opening formed therein which is different from the first opening. 
     According to this embodiment of the ball joint, the ball stud includes a ball portion and a pin portion, wherein the pin portion is disposed in the first slot portion and the ball portion is disposed in the second slot portion. 
     According to this embodiment of the ball joint, the second bearing member is secured to substantially the entire outer surface of the first bearing member. 
     According to this embodiment of the ball joint, the first bearing member is formed from one of metal or plastic and the second bearing member is formed from one of rubber or plastic. 
     According to this embodiment of the ball joint, the second direction defines a minor axis of the ball joint such that when the ball joint is impacted with loads in the direction of the minor axis the first bearing member partially unseats from a portion of a housing internal counterbore whereby the second member is operative to dampen the loads into the ball joint. 
     According to another embodiment, a bearing for a ball joint comprises: a first bearing member formed from a first material and a second bearing member formed from a second dampening material attached to at least a portion of an outer surface of the first bearing member, the first bearing member having and first opened end portion, a main body portion, and a second end portion, wherein the first bearing member includes an inner bearing seat defined by a first slot portion and a second slot portion, wherein the first slot portion is configured to allow the ball stud to articulate in a first direction and the second slot portion is configured to restrict and dampen articulation in a second direction which is generally transverse to the first direction. 
     According to this embodiment of the bearing, the first slot portion has a first shape and a second slot portion has a second shape different from the first shape. 
     According to this embodiment of the bearing, the first shape of the first slot portion is generally oval-shaped and the second shape of the second slot portion is generally concave shaped. 
     According to this embodiment of the bearing, the first slot portion is generally in the center of the bearing and the second slot portion is formed by a pair of generally concave shaped slots disposed on opposed sides of the first slot portion. 
     According to this embodiment of the bearing, the second direction defines a minor axis of the ball joint such that when the ball joint is impacted with loads in the direction of the minor axis the first bearing member partially unseats from a portion of a housing internal counterbore whereby the second member is operative to dampen the loads into the ball joint. 
     Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view, with portions cut away, of an embodiment of a ball joint in accordance with the present invention. 
         FIG. 2  is a sectional view, with portions cut away, of the ball joint. 
         FIG. 3  is another sectional view of the ball joint. 
         FIG. 4  is another sectional view of the ball joint. 
         FIG. 5  is a view taken through a portion of the ball joint showing the possible allowable articulation of the ball joint. 
         FIG. 6  is an exploded view of the bearing (without the damper) and ball stud of the ball joint. 
         FIG. 7  is a view of the bearing with the damper of the ball joint. 
         FIGS. 9-10  are view of the bearing without the damper of the ball joint. 
         FIG. 11  is an enlarged view of a portion of the ball joint showing an operating condition of the ball joint. 
         FIG. 12  is an enlarged view of a portion of the ball joint showing another operating condition of the ball joint. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 1-4 , there is illustrated an embodiment of a ball joint, indicated generally at  10 , in accordance with the present invention. The general structure and operation of the ball joint  10  is conventional in the art. Thus, only those portions of the ball joint 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 ball joint  10  is configured to interconnect relatively movable vehicular parts, such as for example, a steering knuckle or steering yoke, with a control arm, steering yoke or steering knuckle, or other associated parts of the vehicle steering or suspension system. Also, although this invention will be described and illustrated in connection with the particular ball joint  10  disclosed herein, it will be appreciated that this invention may be used in connection with other kinds, types or designs of ball joints if so desired. For example, the ball joint  10  can be used in connection with a vehicle suspension system and/or a ball joint as shown in U.S. Pat. No. 6,042,294 to Urbach, the disclosure of this patent incorporated by reference herein in entirety. 
     As shown in  FIGS. 1-5 , the ball joint  10  includes a socket shell or housing  12  which defines an axis A, a first or upper “throat” bearing  14 , a ball stud  16 , a second or “lower” bearing  18  and a socket plug  20 . In the illustrated embodiment, the housing  12  is formed from a suitable material, such as for example steel or plastic. The housing  12  includes an interior chamber  12 A, an opened first or upper end  12 B, and an opened second or lower end  12 C. The housing preferably further includes an annular groove or recess  12 D provided in an inner side wall thereof. Alternatively, the construction, configuration, or shape of the housing  12  can be other than illustrated and described if so desired. 
     In the illustrated embodiment, the first bearing  14  is formed from a suitable material, such as for example plastic or steel. The first bearing  14  is generally annular in shape and is configured to be disposed in the annular groove  12 D provided in the inner side wall of the housing  12 . Alternatively, the construction, configuration, or shape of the first bearing  14  can be other than illustrated and described if so desired. 
     In the illustrated embodiment, the ball stud  16  is formed from a suitable material, such as for example steel. The ball stud  16  is configured to be operatively centered on the axis A of the ball joint  10 . The ball stud  16  includes a first or shank portion  16 A, a second or ball portion  16 B and a third or pin portion  16 C. The shank portion  16 A of the ball stud  16  is configured to be operatively connected or coupled to a suitable vehicle steering or suspension component, such as for example, a steering knuckle (not shown), in a known manner. For example, the shank portion  16 A can be provided with external threads (not shown) used for connecting the shank portion  16 A, and therefore the ball joint  10 , to the associated vehicle component. Alternatively, the construction, configuration, or shape of the ball stud  16  and/or the method of connecting it to the associated vehicle component can be other than illustrated and described if so desired. 
     In the illustrated embodiment, the second bearing  18  preferably includes at least a first or “inner” member  22  and a second or “outer” member  24 . The first member  22  is generally annular in shape and is formed from a suitable material, such as for example steel, plastic, brass, bronze, or phenolic. In the illustrated embodiment, the first member  22  is preferably formed from high strength low alloy steel, such as for example 50F or 70F stamped steel. 
     In the illustrated embodiment as best shown in  FIGS. 8-10 , the first bearing member  22  includes a first or “upper” flanged opened end portion  22 A, a second or main body portion  22 B, and a second or “lower” end portion  22 C which preferably is also opened. The first member  22  further includes an “inner” bearing seat or surface, indicated generally at  26 , extending generally from the upper end portion  22 A to the lower end portion  22 C. The upper end portion  22 A includes a generally circular shaped opening  30  and the lower end portion  22 C includes a generally oval shaped or elongated slot shaped opening  32 . As best shown in  FIG. 2 , the flanged opened end portion  22 A of the first member  22  is normally disposed adjacent and in engagement with a shoulder  12 E of an internal counterbore  12 F of the housing  12 . 
     In the illustrated embodiment, the bearing seat  26  of the first member  22  includes a uniquely shaped “bidirectional stud travel” slot which is configured to operatively receive the ball portion  16 B and the pin portion  16 C of the ball stud  16  therewithin. As can be seen best in  FIGS. 7 and 8 , in the illustrated embodiment the bidirectional slot includes a first slot portion  26 A having a first shape and a second slot portion  26 B having a second shape. The first slot portion  26 A is formed generally in the center of the main body portion  22 B of the first member  22  and is generally an oval-shaped slot. 
     In the illustrated embodiment, at least the opposed end portions the first slot  26 A preferably extend generally the entire depth of the first member  22 , i.e., extend generally from the flanged upper end portion  22 A to the lower end portion  22 C. As shown in the illustrated embodiment, the first slot portion  26 A includes generally curved end walls and generally planar or flat side walls. In the illustrated embodiment, the first slot portion  26 A is generally configured to receive and support the pin portion  16 C of the ball stud  16  and controls the orientation of the ball stud  16  and allows the articulation of the ball stud  16  in a first direction, generally indicated by double headed arrow D 1  in  FIG. 8 . 
     In the illustrated embodiment, the second slot portion  26 B includes a pair of slots  34 A and  34 B which are formed in the main body portion  22 B of the first member  22  on opposed sides of the first slot portion  26 A. In the illustrated embodiment, the slots  34 A and  34 B are generally concave shaped, such as for example spherical. In the illustrated embodiment, the slots  34 A and  34 B preferably extend only partially the depth of the first member  22  of the second bearing  18 , i.e., extend generally from the flanged upper end portion  22 A toward the lower end portion  22 C, as the slots  34 A and  34 B generally converge or merge with the first slot portion  26 A as indicated by lines  36 A and  36 B, respectively, in  FIG. 7 . 
     In the illustrated embodiment, the second slot portion  26 B is generally configured to receive and support the ball portion  16 B of the ball stud  16  and allows the articulation of the ball stud  16  in the first direction D 1 , but via the pin portion  16 C in the first slot portion  26 A the articulation of the ball stud  16  is restricted in a second direction, generally indicated by double headed arrow D 2 . As can be seen in  FIG. 8 , the second direction D 2  is generally opposite or transverse (i.e., 90 degrees), relative to the first direction D 1 . Thus, the bi-directional slot of the second bearing  18  is operative to allow directional ball stud  16  articulation in the first direction D 1 , while restricting the articulation in the second direction D 2 . 
     In the illustrated embodiment, the second member  24  of the second bearing  18  defines a bushing or damper and is preferably formed from a suitable material, such as for example preferably rubber but can be made from plastic. In the illustrated embodiment, the second member  24  is preferably provided and is bonded, glued, or otherwise permanently attached to an outer surface of the main body portion  22 B of the first member  22 . Preferably, the second member  24  covers the entire outer surface of the main body portion  22 B of the first member  22 . Alternatively, the construction, structure or configuration of the first member  22  and/or the second member  24  of the second bearing  18  and/or the method for attaching the second member  24  to the first member  22  can be other than illustrated and described if so desired. 
     One potential advantage of the illustrated embodiment of the invention is that ball joint second bearing  18 —which preferably includes the stamped “thin wall” steel first member  22  having a dampening second member  24  attached thereto—allows directional stud articulation in one direction while generally restricting articulation in a generally opposite (i.e., ninety degrees). Also, during operation of the vehicle, as the ball joint  10  is impacted with loads in the “restricted stud” direction of a minor axis thereof (i.e., the direction of the minor axis (vehicle fore/aft) being shown in  FIG. 6  generally by arrow M 1 ), the rubber, plastic or similar “dampening” material of the second member  24  of the second bearing  18  allows the second bearing  18  to partially unseat from the shoulder  12 E of the internal counterbore  12 F of the housing  12  (as shown in  FIG. 11 ), whereby the second member  24  is operative to absorb/dampen the loads into the ball joint  10 . The second bearing  18  also allows the ball joint  10  to hang the associated steering linkage at an angle perpendicular or opposed to its center of gravity. The major axis (i.e., the major axis being shown in  FIG. 6  generally by arrow M 2 ), of the ball joint  10  allows for full ball stud  16  articulation in the major axis M 2  in suspension jounce or rebound without any dampening (as shown in  FIG. 12 ). As can be seen from  FIGS. 6 and 8 , the minor axis M 1  of the ball joint  10  generally coincides or is in line with the second direction D 2  of articulation of the ball stud  16  in the second bearing  18  and the major axis M 2  of the ball joint  10  generally coincides or is in line with the first direction D 1  of articulation of the ball stud  16  in the second bearing  18 . 
     The principle and mode of operation of this invention have been described in its preferred embodiments. However, it should be noted that this invention may be practiced otherwise than as specifically illustrated and described without departing from its scope.