Socket Assembly And Method Of Making A Socket Assembly

BACKGROUND OF THE INVENTION

0001<b>1</b>. Field of the Invention

0002The present invention is related, generally, to socket assemblies, and more particularly, to socket assemblies for vehicle suspension and steering systems.

0003<b>2</b>. Related Art

0004Socket assemblies of the type that are used in vehicle suspension and steering systems typically include a ball stud which is movable relative to a housing. Such socket assemblies typically include one or more bearings that are positioned within the housing and are in sliding contact with a ball portion of the ball stud to facilitate the rotation of the ball stud relative to the housing. The bearings are typically made of either metal or a hard plastic material.

0005Such socket assemblies are typically either of the radial loaded type, compression loaded type or the tension loaded type, depending on the configuration of the suspension or steering system. In many known types of compression-style socket assemblies, when a radial load is applied to the ball stud, the ball stud will try to walk up the radius of the lower bearing, thereby reducing the surface of contact between the ball stud and the lower bearing. The term lower bearing is interchangeable with the term backing bearing throughout the following description of this invention.

SUMMARY OF THE INVENTION AND ADVANTAGES

0006One aspect of the present invention is for a socket assembly. The socket assembly includes a housing with an inner bore that extends along an axis from a wall at a generally closed first end to an open second end. The socket assembly further includes a ball stud with a ball portion that is received in the inner bore of the housing and a shank portion which projects out of the inner bore through the open second end. A backing bearing is disposed in the inner bore and is movable in a radial direction relative to the housing. The backing bearing presents a curved first bearing surface which is in sliding contact with an outer surface of the ball portion of the ball stud. A radial ring with an annular shape is also disposed in the inner bore of the housing. The radial ring presents a second bearing surface which is in sliding contact with an equator of the ball portion. The socket assembly further includes an exit bearing which is made as a separate piece from the radial ring and which has a curved third bearing surface that is in sliding contact with an opposite hemisphere of the ball portion from the first bearing surface.

0007During operation, the floating (movable) backing bearing and the radial ring support loads independently of one another. Specifically, the radial ring supports all or substantially all of the radial loads, and the backing bearing supports the axial loads. The floating nature of the backing bearing allows the backing bearing to self-center on the ball portion of the ball stud and move with the ball stud when radial loads are applied. That is, the ball stud and the backing bearing move together until the stud makes contact with the radial ring at the equator. This keeps the ball stud from trying to walk up the spherical radius of the backing bearing, thereby maintaining a large area of contact between the ball portion and the backing bearing at all times. The large area of contact between the ball portion and the backing bearing reduces wear in the ball stud and the backing bearing, thereby improving the operating life of the socket assembly as compared to other known socket assemblies.

0008According to another aspect of the present invention, the third bearing surface of the exit bearing is biased against the outer surface of the ball stud.

0009According to yet another aspect of the present invention, a dust boot is sealed against the housing and the shank portion of the ball stud, and the dust boot includes a spring which is at least partially embedded within a rubber body for biasing the third bearing surface of the exit bearing against the outer surface of the ball portion of the ball stud.

0010According to still another aspect of the present invention, the housing presents a radially inwardly extending lip at the open second end for trapping the exit bearing, boot and cover plate in the inner bore.

0011According to a further aspect of the present invention, the first bearing surface, second bearing surface and third bearing surface all present a plurality of lubricant grooves for distributing a lubricant throughout said inner bore of said housing.

0012According to yet a further aspect of the present invention, the housing presents a shoulder that faces towards the open second end of the housing, and the radial ring abuts the shoulder.

0013According to still a further aspect of the present invention, the spring is a Belleville washer.

0014According to another aspect of the present invention, the socket assembly further includes a thrust washer which is positioned between the wall of the housing and the backing bearing.

0015According to yet another aspect of the present invention, the thrust washer or the backing bearing presents at least one lubricant channel for conveying a lubricant between the thrust washer and the backing bearing and outer circumference of the backing bearing and inner circumference of the bore of the housing.

0016Another aspect of the present invention is a method of making a socket assembly. The method includes the step of preparing a housing with an inner bore which extends from a wall at a generally closed first end to an open second end. The method continues with the step of inserting a backing bearing with a curved first bearing surface into the inner bore of the housing such that the backing bearing is movable in a radial direction within the inner bore relative to the housing. The method proceeds with the step of inserting a ball portion of a ball stud into the inner bore of the housing and wherein the ball stud has a shank portion which extends from the ball portion out of the inner bore through the open second end of the housing and wherein a curved outer surface of the ball portion is in sliding contact with the first bearing surface of the backing bearing. The method proceeds with the step of inserting a radial ring with a second bearing surface into the inner bore of the housing with the second bearing surface being in sliding contact with an equator of the ball portion of the ball stud. The method continues with the step of inserting an exit bearing with a curved third bearing surface into the inner bore of the housing such that the third bearing surface is brought into sliding contact with the curved outer surface of the ball portion of the ball stud.

0017According to another aspect of the present invention, the method further includes the step of deforming the housing adjacent the open second end of the inner bore to trap the exit bearing in the inner bore.

0018According to yet another aspect of the present invention, the step of deforming the housing is further defined as swaging the housing.

0019According to still another aspect of the present invention the method further includes the step of sealing a dust boot against the shank and the housing wherein the swaging of the housing traps one end of the dust boot between a cover plate or the inwardly extending radial lip of the housing and an upper surface of the exit bearing.

0020According to a further aspect of the present invention, the dust boot includes a spring which is at least partially embedded in a rubber body and wherein the spring biases the third bearing surface of the exit bearing against the outer surface of the ball portion of the ball stud. According to yet a further aspect of the present invention, the method further includes the step of injecting a lubricant into the inner bore of the housing.

0021According to yet a further aspect of the present invention, the method further includes the step of inserting a thrust washer into the inner bore of the housing before the step of inserting the backing bearing into the inner bore of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

<figref idref="DRAWINGS">FIG. 1</figref> is a perspective view of an exemplary embodiment of a socket assembly constructed according to an aspect of the present invention;

<figref idref="DRAWINGS">FIG. 2</figref> is an exploded and cross-sectional view of the socket assembly of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 3</figref> is a cross-sectional view of a housing of the socket assembly of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 4</figref> is a cross-sectional view of the socket assembly of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 5</figref> is an enlarged view of a portion of <figref idref="DRAWINGS">FIG. 4</figref>;

<figref idref="DRAWINGS">FIG. 6</figref> is another enlarged view of a portion of <figref idref="DRAWINGS">FIG. 4</figref>; and

<figref idref="DRAWINGS">FIG. 7</figref> is a cross-sectional view of the socket assembly of <figref idref="DRAWINGS">FIG. 1</figref> and illustrating a flow path for grease within an interior of the socket assembly.

DESCRIPTION OF THE ENABLING EMBODIMENT

0030Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, an exemplary embodiment of an improved socket assembly <b>20</b> (specifically, a ball joint assembly) is generally shown in <figref idref="DRAWINGS">FIGS. 1-5</figref>. In the exemplary embodiment, the socket assembly <b>20</b> is configured for joining a control arm (not shown) or axle (not shown) with a knuckle (not shown) of a vehicle suspension assembly. However, it should be appreciated that the socket assembly <b>20</b> could find uses in tie rod ends or in a wide range of automotive and non-automotive applications.

0031The socket assembly <b>20</b> includes a housing <b>22</b> with an inner bore that extends along an axis A from a closed first end <b>24</b> to an open second end <b>26</b>. At the closed first end <b>24</b>, the housing <b>22</b> presents a lower wall <b>28</b> with a lubricant opening <b>30</b> that receives a grease fitting <b>32</b> (also known as a zerk fitting) for conveying a lubricant, such as grease, into the inner bore to initially lubricate the components of the socket assembly <b>20</b> and to re-lubricate the socket assembly <b>20</b> as part of routine maintenance. The housing <b>22</b> is preferably made of a metal, such as steel or a steel alloy, and may be shaped through any suitable process or combination of processes including, for example, forging, casting, machining from a billet, etc. In the exemplary embodiment, the housing <b>22</b> is a cartridge for press-fitting into an opening in the control arm. However, the housing could alternately be integrally formed with another component, e.g., a control arm or a tie rod end.

0032The inner bore of the housing <b>22</b> has a progressively increasing diameter from the closed first end <b>24</b> to the open second end <b>26</b>. Specifically, the inner bore has a first portion <b>34</b> with a generally constant first diameter D₁adjacent the closed first end <b>24</b>, a second portion <b>36</b> with an increasing diameter and a third portion <b>38</b> with a generally constant second diameter D₂adjacent the open second end <b>26</b>. As shown, the second diameter D₂of the third portion <b>38</b> is greater than the first diameter D₁of the first portion <b>34</b>. An inner wall of the housing <b>22</b> at the second portion <b>36</b> of the inner bore is curved to increase the diameter of the second portion <b>36</b> in an axial direction towards the open second end <b>26</b>. Between the second and third portions <b>36</b>, <b>38</b> of the inner bore, the housing <b>22</b> presents a shoulder <b>40</b> which faces towards the open second end <b>26</b>.

0033A backing bearing <b>42</b> is received in the first portion <b>34</b> of the inner bore and has a semi-spherically curved first bearing surface <b>44</b> which faces axially towards the second open end <b>26</b>. The backing bearing <b>42</b> has an outer surface with an outer diameter which is less than the first diameter D₁of the first portion <b>34</b> to present a gap (shown in <figref idref="DRAWINGS">FIG. 5</figref>) between the outer surface of the backing bearing <b>42</b> and an inner surface of the housing <b>22</b>. As such, the backing bearing <b>42</b> is allowed to float in a radial direction in the first portion <b>34</b> of the inner bore within the limits established by the gap. The backing bearing <b>42</b> also includes a lubricant opening <b>46</b> which is aligned with the lubricant opening <b>30</b> of the lower wall <b>28</b> of the housing <b>22</b>. The first bearing surface <b>44</b> of the exemplary embodiment is provided with a plurality of first grooves <b>48</b> formed thereon for distributing a lubricant from the lubricant opening <b>46</b> into the second portion <b>36</b> of the inner bore.

0034The socket assembly <b>20</b> further includes a ball stud <b>50</b> which is partially received in the inner bore of the housing <b>22</b>. Specifically, the ball stud <b>50</b> includes a ball portion <b>52</b> that is fully disposed in the inner bore and a shank portion <b>54</b> which projects out of the inner bore through the open second end <b>26</b>. The shank portion <b>54</b> extends from the ball portion <b>52</b> to a distal end which is threaded for receiving a nut to connect the shank portion <b>54</b> with another component, e.g., a knuckle. The ball portion <b>52</b> of the ball stud <b>50</b> has a generally semi-spherically curved outer surface which has a similar radius of curvature to the first bearing surface <b>44</b> of the backing bearing <b>42</b>. The outer surface of the ball portion <b>52</b> is in sliding contact with the first bearing surface <b>44</b> to allow the ball stud <b>50</b> to rotate and pivot relative to the backing bearing <b>42</b> and the housing <b>22</b> during operation of the suspension assembly. The backing bearing <b>42</b> is preferably made of metal, such as steel or a steel alloy. As shown in <figref idref="DRAWINGS">FIG. 5</figref>, the lubrication channels <b>58</b> also allow lubricant to flow into the gap between the backing bearing <b>42</b> and the first portion <b>34</b> of the inner bore of the housing <b>22</b> from which the lubricant is able to enter the second portion <b>36</b> of the inner bore.

0035A thrust washer <b>56</b> is positioned in the first portion <b>34</b> of the inner bore between the backing bearing <b>42</b> and the lower wall <b>28</b> of the housing <b>22</b> for allowing radial movement of the backing bearing <b>42</b> relative to the housing <b>22</b>. In the exemplary embodiment, a lower surface of the backing bearing <b>42</b> opposite of the first bearing surface <b>44</b> presents a plurality of lubrication channels <b>58</b> for conveying the lubricant between the backing bearing <b>42</b> and the thrust washer <b>56</b> to reduce friction between the backing bearing <b>42</b> and the thrust washer <b>56</b>.

0036The socket assembly <b>20</b> further includes a radial ring <b>60</b> which is positioned in the third portion <b>38</b> of the inner bore and abuts the shoulder <b>40</b> of the housing <b>22</b>. The radial ring <b>60</b> is a separate piece from the backing bearing <b>42</b> and is spaced axially therefrom by a gap in the second portion <b>36</b> of the inner bore. The radial ring <b>60</b> is generally annular in shape, and a radially inwardly facing surface of the radial ring <b>60</b> is a second bearing surface <b>62</b> which is in sliding contact with an equator of the ball portion <b>52</b> of the ball stud <b>50</b>. The second bearing surface <b>62</b> may either be semi-spherically curved or it may be generally linear as viewed in cross-section. In the exemplary embodiment, the second bearing surface <b>62</b> is provided with a plurality of second lubrication grooves <b>64</b> for distributing lubricant around the surface-to-surface contact area between the second bearing surface <b>62</b> and the outer surface of the ball portion <b>52</b> of the ball stud <b>50</b> conveying lubricant in the inner bore axially across the radial ring <b>60</b>. In the second portion <b>36</b> of the inner bore, the gap between the backing bearing <b>42</b> and the radial ring <b>60</b> acts as a lubrication reservoir which holds the lubricant.

0037An exit bearing <b>65</b> is received in the third portion <b>38</b> of the inner bore and has a third bearing surface <b>66</b> which has a similar radius of curvature as the ball portion <b>52</b> and is in sliding contact with the outer surface of the ball portion <b>52</b> of the ball stud <b>50</b>. The exit bearing <b>65</b> has a generally flat or planar top surface which faces towards the open second end <b>26</b> of the inner bore. In the exemplary embodiment, the third bearing surface <b>66</b> is provided with a plurality of third lubrication grooves <b>68</b> for distributing the lubricant around the surface-to-surface contact between the third bearing surface <b>66</b> and the ball portion <b>52</b> of the ball stud <b>50</b> and for conveying the lubricant in the inner bore of the housing <b>22</b> in an axial direction across the exit bearing <b>65</b>.

0038During operation of the suspension assembly, the radial ring <b>60</b> transfers all or substantially all of the radial forces between the ball stud <b>50</b> and the housing <b>22</b> while the backing and exit bearings <b>42</b>, <b>65</b> transfer all or substantially all of the axial forces between the ball stud <b>50</b> and the housing <b>22</b>.

0039The socket assembly <b>20</b> further includes a dust boot <b>70</b> which is sealed against the housing <b>22</b> and against the shank portion <b>54</b> of the ball stud <b>50</b> for maintaining the lubricant in the interior of the socket assembly <b>20</b> and for keeping contaminants outside of the socket assembly <b>20</b>. The dust boot <b>70</b> includes a first boot end which presents a radially outwardly extending flange <b>72</b> with a spring in the form of a Belleville washer <b>74</b> that is embedded within a boot body <b>76</b> at the radially outwardly extending flange <b>72</b>. The boot body <b>76</b> is made of a flexible sealing material, such as rubber or a plastic material. The radially outwardly extending flange <b>72</b> is in surface to surface contact with the top surface of the exit bearing <b>65</b>.

0040A cover plate <b>78</b> is positioned at an opposite side of the radially outwardly extending flange <b>72</b> of the dust boot <b>70</b>. The housing <b>22</b> has a radially inwardly extending lip <b>80</b> which traps the cover plate <b>78</b> and the radially outwardly extending flange <b>72</b> of the dust boot <b>70</b> between the radially inwardly extending lip <b>80</b> and the exit bearing <b>65</b>. This also has the effect of allowing the Belleville washer <b>74</b> in the dust boot <b>70</b> to impart a preload force against the exit bearing <b>65</b> to bias the third bearing surface <b>66</b> of the exit bearing <b>65</b> against the outer surface of the ball portion <b>52</b> of the ball stud <b>50</b>. The radially inwardly extending lip <b>80</b> is preferably formed into the housing <b>22</b> by swaging the housing <b>22</b> at the open second end <b>26</b> of the inner bore.

0041Another aspect of the present invention is a method of making a socket assembly <b>20</b>, such as the exemplary socket assembly shown in <figref idref="DRAWINGS">FIGS. 1-5</figref>. The method includes the step of preparing a housing <b>22</b> with an inner bore that extends from a lower wall <b>28</b> at a generally closed first end <b>24</b> to an open second end <b>26</b>. The method continues with the step of inserting a thrust washer <b>56</b> into the inner bore. The method proceeds with the step of inserting a backing bearing <b>42</b> into the inner bore such that the backing bearing <b>42</b> is movable in a radial direction within the inner bore and such that the backing bearing <b>42</b> is slidable relative to the housing <b>22</b> on the thrust washer <b>56</b>. Preferably, a lower surface of the backing bearing <b>42</b> or an upper surface of the thrust washer <b>56</b> is provided with one or more lubrication channels <b>58</b> for distributing the lubricant across the interface between the backing bearing <b>42</b> and the thrust washer <b>56</b>. The method continues with the step of inserting a ball portion <b>52</b> of a ball stud <b>50</b> into the inner bore of the housing <b>22</b>. The ball stud <b>50</b> also has a shank portion <b>54</b> which extends from the ball portion <b>52</b> out of the inner bore through the open second end <b>26</b> of the housing <b>22</b> and wherein a curved outer surface of the ball portion <b>52</b> is in sliding contact with the first bearing surface <b>44</b> of the backing bearing <b>42</b>. The method proceeds with the step of inserting a radial ring <b>60</b> with a second bearing surface <b>62</b> into the inner bore of the housing <b>22</b> such that the second bearing surface <b>62</b> of the radial ring <b>60</b> is in sliding contact with the equator of the ball portion <b>52</b> of the ball stud <b>50</b>. The method continues with the step of inserting an exit bearing <b>65</b> with a curved third bearing surface <b>66</b> into the inner bore of the housing <b>22</b> such that the third bearing surface <b>66</b> is brought into sliding contact with the curved outer surface of the ball portion <b>52</b> of the ball stud <b>50</b>. The method proceeds with the steps of engaging a radially outwardly extending flange <b>72</b> of a dust boot <b>70</b> with a top surface of the exit bearing <b>65</b> and inserting a cover plate <b>78</b> into the inner bore. The method continues with the step of deforming, such as through swaging, the housing <b>22</b> at the open second end <b>26</b> to trap the radially outwardly extending flange <b>72</b> and the cover plate <b>78</b> between a radially inwardly extending lip <b>80</b> of the housing <b>22</b> and the exit bearing <b>65</b>. Preferably, the dust boot <b>70</b> is provided with a spring, such as a Belleville washer <b>74</b>, at least partially embedded in the radially outwardly extending flange <b>72</b> of the dust boot <b>70</b> such that the Belleville washer <b>74</b> imparts a biasing force against the exit bearing <b>65</b> to bias the third bearing surface <b>66</b> against the curved outer surface of the ball portion <b>52</b> of the ball stud <b>50</b>. The method continues with the step of injecting a lubricant into the inner bore of the housing <b>22</b>.

0042It should be appreciated that the use of the terms “upper” and “lower” herein is in reference to the orientation of the socket assembly <b>20</b> in the Figures and is not considered to require a particular orientation or otherwise be limiting.

0043Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims.