Abstract:
An improved bearing for use in movable sockets and suspension joints. The improved bearing is annular, having an outer dimension sized to seat within the housing of a suspension joint or movable socket. An inner surface of the bearing is configured to receive the head of an articulating stud within the housing. Three or more radial slots are disposed on the inner surface. Each radial slot disposed on one-half of the bearing inner surface has a unique radial dimension, such that the radial slots are optimally configured to minimize stress and stiffness within the improved bearing, whereby the bearing can be seated within the housing in a radially and rotationally locked configuration, but remain movable in an axial direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not Applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
       [0002]     Not Applicable.  
       BACKGROUND OF THE INVENTION  
       [0003]     The present invention relates to suspension joint bearings, and in particular, to an improved suspension joint bearing having non-uniform lubrication and stress-relief slots disposed in optimized locations about a circumference thereof to permit axial movement and simultaneous radial lock-up within a bearing housing.  
         [0004]     Conventional suspension joints, and other movable sockets are used, for example, in automotive steering and suspension applications. The sockets comprise a housing having a circular cylindrical or conical internal surface, a ball stud with a stud head contained in the housing, and one or more bearing members supporting the stud head within the housing. Traditionally, the bearing members are composed of a synthetic resin or sintered alloy. These components are installed into the housing through an opening, with the stud extending outward through an axially disposed opening which may either be the same opening through which the components were installed, or an axially opposite opening.  
         [0005]     Traditionally, if two openings are present in the housing, one opening is closed by means of a cover-plate, spun, swaged, or welded in place. Once secured in place, the cover-plate presses on the bearing members either directly or indirectly through a resilient rubber or elastic steel intermediate component. Alternatively, for housings having only a single opening, once the components are in place, and the ball stud is protruding from the opening, the peripheral edges of the opening are swagged or rolled to retain the components in place, while simultaneously permitting movement of the ball stud.  
         [0006]     Conventional bearing components within the housing, against which the stud head or moveable component is rotated and/or articulated, perform best when the sliding surfaces are fully hardened, as it is better able to withstand the stresses and frictional wear associated with movement of the conventional bearing components. Bearing components in a movable socket are subjected to rotational, axial, and radial loads. Accordingly, the use of hardened materials greatly extends the useful life of the bearing components and the housing.  
         [0007]     Once assembled, movable sockets may be utilized as load carrying members in numerous mechanical systems, including automotive vehicle suspension and steering systems. Movable sockets or ball-joints employed in these applications are subjected to various operating conditions, and may be required to carry substantial loads. When wear develops, the performance of the movable socket or ball-joint degrades and, in the case of automotive applications, may result in erratic steering or excessive looseness and play in the vehicle suspension system. Accordingly, it is desired to minimize internal wear in the movable sockets or suspension joints.  
         [0008]     A conventional lower bearing in a suspension joint typically includes a number of equidistantly spaced radial slots of uniform depth. These slots are intended to provide a limited degree of flexibility in the bearing, and to provide channels for the flow of lubricant to the bearing surfaces in the suspension joint, reducing internal wear and extending the operational life of the suspension joint. This configuration of radial slots either has a very high stress associated with the radial slots, or a very high stiffness. If the bearing has a high stress associated with the radial slots, the bearing may break during the process of assembling the suspension joint or during subsequent operation thereof. If the bearing has a high stiffness, two possible problems may arise. First, if the outer radial dimension of the bearing is greater than the inner radial dimension of the housing in which it is seated, the bearing may be difficult to fit within the housing during assembly. Once assembled in the housing, the bearing may become “locked” against movement in the suspension joint axial direction, rendering other axial compliance members, such as Belleville washers, disposed within the housing non-functional. Alternatively, if the outer radial dimension of the bearing is smaller than the inner radial dimension of the housing, the bearing will be loose within the housing in a radial direction. A loose bearing will rotate within the housing during service and create impact forces in the housing, greatly decreasing the useful life of the suspension joint.  
         [0009]     Accordingly, it is desirable to provide an improved socket lower bearing which retains the functionality of providing flexibility in a radial direction, delivering lubricant to the bearing surfaces, but which is minimally stressed, and which is configured to remain “locked” against rotational movement direction while simultaneously permitting movement in an axial direction.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     Briefly stated, the present invention provides an improved bearing for use in movable sockets and suspension joints. The improved bearing is annular, having an outer dimension sized to seat within the housing of a suspension joint or movable socket. An inner surface of the bearing is generally hemispherically or conically configured to receive the head of an articulating stud within the housing. Three or more radial slots are disposed in the inner surface. The radial slots each have non-uniform radial dimensions, and are optimally configured to minimize stress and stiffness within the improved bearing, whereby the bearing can be seated within the housing in a radially locked configuration, but remain movable in an axial direction.  
         [0011]     In an alternate embodiment of the present invention, an improved lower bearing for use in a suspension joint is provided. The improved lower bearing is annular, having an outer dimension sized to seat within the housing of a suspension joint or movable socket. An inner surface of the bearing is generally hemispherically or conically configured to receive the head of an articulating stud within the housing. Five radial slots are symmetrically disposed in the inner surface, together with a break or discontinuity in the annular form. A first radial slot is provided with a first radial dimension. A first pair of adjacent radial slots are disposed on each side of the first radial slot, and are configured with a second radial dimension which is greater than the first radial dimension. A second pair of radial slots, disposed axially opposite the first pair of adjacent radial slots are configured with a third radial dimension which is greater than the second radial dimension. The break or discontinuity in the annular form of the bearing is disposed axially opposite the first radial slot. Each of the radial slots and discontinuity are optimally configured to minimize stress and stiffness within the improved bearing, whereby the bearing can be seated within the housing in a radially locked configuration, but remain movable in an axial direction.  
         [0012]     The foregoing and other objects, features, and advantages of the invention as well as presently preferred embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0013]     In the accompanying drawings which form part of the specification:  
         [0014]      FIG. 1  is an exploded sectional view of a conventional ball and socket joint;  
         [0015]      FIG. 2  is an assembled section view of the ball and socket joint of  FIG. 1 ;  
         [0016]      FIG. 3  is a top view of a conventional slotted bearing;  
         [0017]      FIG. 4  is a top view of a slotted bearing of the present invention;  
         [0018]      FIG. 5  is a top view of an alternate slotted bearing of the present invention;  
         [0019]      FIG. 6  is a sectional view of the bearing of  FIG. 5 ; and  
         [0020]      FIG. 7  is a top view a second alternate slotted bearing of the present invention.  
         [0021]     Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]     The following detailed description illustrates the invention by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the invention, describes several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.  
         [0023]     Turning to  FIG. 1 , a conventional suspension joint  8  is shown in an exploded view. A housing  10 , within which the various internal components of the ball-joint  8  are enclosed, is generally cylindrical, with a central bore  12  of non-uniform radius R, having a closed posterior end  14  and an open anterior end  16 . The exterior surface  18  of housing  10  may follow the general contour of the central bore  12 . In the embodiment illustrated, the surface  18  has an annular flange  20  formed in it. The flange  20  is used to limit engagement of ball-joint  10  to other components (not shown). As may be appreciated, the flange  20  also may be adapted for other specific kinds of installations employing threads or other connectors (not shown).  
         [0024]     To assemble the ball-joint  8 , a Belleville washer  22  sized to fit within the central bore  12  is seated against the closed posterior end  14 . When the components of the suspension joint are assembled, the Belleville washer  22  provides resilient axial compliance. Next, a lower bearing  24  sized to fit within central bore  12  is seated within housing  10 . The lower bearing  24  includes a central bore  26  axially aligned with a vertical axis VA of the housing, and an outer surface  28  of lower bearing  24  is designed to correspond to the curvature of interior of the central bore  12 .  
         [0025]     A stud  30  having a generally cylindrical body  32  and an enlarged spherical head  34  is placed in the central bore  12 , such that the spherical head  34  engages a corresponding hemispherical inner surface  36  of the bearing  24  seated within the housing  10 . The body  32  of the stud  30  includes a neck portion  38  adjacent the spherical head  34 , a central portion  40 , and an upper portion  42  of a narrow uniform diameter. The neck portion  38  is sized to fit within the central bore  12  of housing  10 , with the central portion  40  and upper portion  42  extending through the open anterior end  16 , externally of housing  10 . To secure the spherical head  34  within the housing  10 , a second, or upper bearing  44  is seated in the central bore  12 , having a curved inner surface  46  which surrounds a portion of the spherical head  34  adjacent the neck portion  38 . A reduced thickness annular region  47  of the housing  10  is then rolled or swagged inward to retain the upper bearing  44  within the central bore  12 , securing the stud  30  in place. Finally, a dust boot  48  is secured about the exposed portion of the stud  30  to the housing  10 .  
         [0026]     When assembled, as illustrated in  FIG. 2 , the spherical head  34  seated between the lower bearing  24  and the upper bearing  44  provides for a limited range of conical movement of stud  30 . Those skilled in the art will readily recognize that numerous shapes and configurations for housing  10  and stud  30  are possible, together with associated configurations of bearings  24  and  44 , depending upon the particular application for which the suspension joint  8  is intended. For example, the stud  30  may include a hemispherical, conical, or cylindrical head, or the cylindrical body may include threads  50 , bores as at  52 , or grooves for attachment of external components (not shown).  
         [0027]     As indicated above, those skilled in the art will recognize that the various internal components of the suspension joint  8  secured within the housing  10  may be varied in size and shape depending upon the particular application for which the suspension joint  8  is designed, and accordingly, the above described ball-joint  8  is merely exemplary of one embodiment in which a bearing of the present invention may be utilized.  
         [0028]     Turning to  FIG. 3 , a top plan view of a conventional lower bearing  24  is shown.  
         [0029]     The bearing  24  is generally annular, having an outer radius R 1  sized to seat within the central bore  12  of the housing  10 . The hemispherical shaped inner surface  36  is interrupted by a number of uniformly sized radial slots  54 , and a discontinuity  56 . Each slot  54 , and the discontinuity  56 , has an identical radial depth R 2 , and an identical width W, and is equidistantly spaced in a uniform pattern about the axis VA of the bearing  24 .  
         [0030]     Turning to  FIG. 4 , an improved lower bearing  100  of the present invention for replacement of lower bearing  24  in suspension joint  8  is shown in a top plan view. The bearing  100  defines an annular body having an outer radial dimension Rx sized to seat within the central bore  12  of the housing  10 , such that the bearing  100  is locked against radial or rotational movement within the central bore  12 , but movable in the axial direction along axis VA after assembly of the suspension joint  8 . As shown in  FIG. 4 , the inner surface  101  of the bearing  100  preferably includes five radial slots, designated generally by  102  as well as a break or discontinuity  104  in the bearing annular body  100 . With the discontinuity  104  aligned with the Y-axis, the radial slots  102  and discontinuity  104  are symmetrically disposed about the Y-axis.  
         [0031]     Preferably, the radial slots  102  on each side of a plane bisecting the bearing  100  from top to bottom along the Y-axis are mirror images. Each radial slot  102  on one side of the Y-axis plane has a unique radial dimension, such that no more than two radial slots  102  in the bearing  100  have identical radial dimensions.  
         [0032]     Preferably, radial slot  102 A has a radial dimensions of Ra, radial slots  102 B on opposite sides of the Y-axis plane each have a radial dimension Rb, where Rb&gt;Ra, and radial slots  102 C on opposite sides of the Y-axis plane, each axially opposite a radial slot  102 B, each have a radial dimension Rc, where Rc&gt;Rb. The discontinuity  104  in the bearing  100  is disposed axially opposite from radial slot  102 A, and provides a complete break in the annular configuration of the bearing  100 .  
         [0033]     As shown in  FIG. 4 , preferably each radial slot  102 A,  102 B, and  102 C is preferably non-uniform in size, having a generally enlarged end portion  106  with a circular cross-section, and a reduced width neck portion  108 , selected to minimize stresses and stiffness in the bearing  100  associated with the radial slots  102  while maintaining adequate bearing to stud contact. Those of ordinary skill in the art will recognize that the specific shape of each radial slot  102  may be varied from that shown in  FIG. 4 , and that the slots may be constructed of a uniform width along their radial dimension, or have an end portion  106  having a diameter equal to the width of the neck portion  108 . Correspondingly, the number of radial slots  102  in the bearing  100  is not limited to five, but rather, may be any number greater than three. Radial slots  102  and optional discontinuity  104  are disposed about the inner surface  101  of the bearing  100  such that stresses within the bearing are equally distributed. Preferably, opposite sides of the Y-axis of the bearing  100  are mirror images.  
         [0034]     During assembly and operation of a suspension joint  8  utilizing a bearing  100  of the present invention, it can be seen that the stresses within the bearing  100  are minimized and evenly distributed around all of the slots  102 , thereby decreasing fatigue and increasing wear life for the bearing  100 . Similarly, the fit tolerance of the bearing  100  within the housing  10  is improved over the fit tolerance of conventional bearings  24 , such that the bearing  100  is locked within the central bore  12  in a radial direction, but remains free to move axially within the central bore  12 , such that axial compliance members  22  are operative to regulate axial movement of the stud  30 .  
         [0035]     Turning to  FIG. 5 , an alternate embodiment  200  of the lower bearing of the present invention for replacement of lower bearing  24  in suspension joint  8  is shown in a top plan view. The bearing  200  defines an annular body having an outer radial dimension Rx sized to seat within the central bore  12  of the housing  10 , such that the bearing  200  is locked against radial or rotational movement within the central bore  12 , but movable in the axial direction along axis VA after assembly of the suspension joint  8 . As shown in  FIG. 6 , the inner surface  201  of the bearing  200  is generally conical, preferably includes five radial slots, designated generally by  202  as well as a break or discontinuity  204  in the bearing annular body  200 . With the discontinuity  204  aligned with the Y-axis, the radial slots  202  are symmetrically disposed about the Y-axis.  
         [0036]     Preferably, the radial slots  202  on each side of a plane bisecting the bearing  200  from top to bottom along the Y-axis are mirror images. Each radial slot  202  on one side of the Y-axis plane has a unique radial dimension, such that no more than two radial slots  202  in the bearing  200  have identical radial dimensions.  
         [0037]     Preferably, radial slot  202 A has a radial dimension of Rm, radial slots  202 B on opposite sides of the Y-axis plane each have a radial dimension Rn, where Rn&gt;Rm, and radial slots  202 C on opposite sides of the Y-axis plane, each axially opposite a radial slot  202 B, each have a radial dimension Ro, where Ro&gt;Rn. The discontinuity  204  in the bearing  200  is disposed axially opposite from radial slot  202 A, and provides a complete break in the annular configuration of the bearing  200 .  
         [0038]     As shown in  FIG. 5 , preferably each radial slot  202 A,  202 B, and  202 C is non-uniform in size, having a generally enlarged end portion  206  with a circular cross-section, and a reduced width neck portion  208 , selected to minimize stresses and stiffness in the bearing  200  associated with the radial slots  202  while maintaining adequate bearing to stud contact. Those of ordinary skill in the art will recognize that the specific shape of each radial slot  202  may be varied from that shown in  FIG. 5 . Correspondingly, the number of radial slots  202  in the bearing  200  is not limited to five, but rather, may be any number greater than three. Radial slots  202  and optional discontinuity  204  are disposed about the inner surface  201  of the bearing  200  such that stresses within the bearing are equally distributed. Preferably, opposite sides of the Y-axis of the bearing  200  are mirror images.  
         [0039]     During assembly and operation of a suspension joint  8  utilizing a bearing  200  of the present invention, it can be seen that the stresses within the bearing  200  are minimized and evenly distributed around all of the slots  202 , thereby decreasing fatigue and increasing wear life for the bearing  200 . Similarly, the fit tolerance of the bearing  200  within the housing  10  is improved over the fit tolerance of conventional bearings  24 , such that the bearing  200  is locked within the central bore  12  in a radial direction, but remains free to move axially within the central bore  12 , such that axial compliance members  22  are operative to regulate axial movement of the stud  30 .  
         [0040]     Turning to  FIG. 7 , an alternate embodiment  300  of the lower bearing of the present invention for replacement of lower bearing  24  in suspension joint  8  is shown in a top plan view. The bearing  300  defines an annular body having an outer radial dimension Rx sized to seat within the central bore  12  of the housing  10 , such that the bearing  300  is locked against radial or rotational movement within the central bore  12 , but movable in the axial direction along axis VA after assembly of the suspension joint  8 . The inner surface  301  of the bearing  200  either hemispherical, such as shown in bearing  100 , or conical as shown in bearing  200 , and preferably includes six radial slots, designated generally by  302  as well as a break or discontinuity  304  in the bearing annular body  300 . With the discontinuity  304  aligned with the Y-axis, the radial slots  302  are disposed in mirror-image about the Y-axis plane, with each slot on one side of the Y-axis plane having a unique radial dimension, such that no more than two radial slots  302  in the bearing  300  have identical radial dimensions.  
         [0041]     Preferably, radial slots  302 A on opposite sides of the Y-axis each have a radial dimensions of Rp, radial slots  302 B on opposite sides of the Y-axis each have a radial dimension Rq, where Rq&gt;Rp, and radial slots  302 C on opposite sides of the Y-axis, each axially opposite a radial slot  302 A, each have a radial dimension Rs, where Rs&gt;Rq. The discontinuity  304  in the bearing  300  is disposed on the Y-axis, and provides a complete break in the annular configuration of the bearing  300 .  
         [0042]     As shown in  FIG. 7 , preferably each radial slot  302 A,  302 B, and  302 C is non-uniform in size, having a generally enlarge end portion  306  with a circular cross-section, and a reduced width neck portion  308 , selected to minimize stresses and stiffness in the bearing  300  associated with the radial slots  302  while maintaining adequate bearing to stud contact. Those of ordinary skill in the art will recognize that the specific shape of each radial slot  302  may be varied from that shown in  FIG. 7 . Correspondingly, the number of radial slots  302  in the bearing  300  is not limited to six, but rather, may be any number greater than three. Radial slots  302  and optional discontinuity  304  are disposed about the inner surface  301  of the bearing  300  such that stresses within the bearing are equally distributed. Preferably, opposite sides of the Y-axis of the bearing  300  are mirror images.  
         [0043]     During assembly and operation of a suspension joint  8  utilizing a bearing  300  of the present invention, it can be seen that the stresses within the bearing  300  are minimized and evenly distributed around all of the slots  302 , thereby decreasing fatigue and increasing wear life for the bearing  300 . Similarly, the fit tolerance of the bearing  300  within the housing  10  is improved over the fit tolerance of conventional bearings  24 , such that the bearing  300  is locked within the central bore  12  in a radial direction, but remains free to move axially within the central bore  12 , such that axial compliance members  22  are operative to regulate axial movement of the stud  30 .  
         [0044]     Preferably, bearings  100 ,  200 ,  300  are formed from a powdered metal using a conventional sintering process, however, those of ordinary skill in the art will recognize that the inventive features of the present invention may be utilized with any of a variety of bearing materials conventionally utilized in movable sockets or suspension joints, such as formed metals or plastics. Furthermore, those of ordinary skill will recognize that the present invention is not limited in application to lower bearings in a suspension joint, but may be utilized in upper bearings as well.  
         [0045]     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results are obtained. As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.