Snap-in bearing for automotive ball joint

A self-aligning rotating joint, for mounting in a first component and connecting to a second component, the rotating joint comprising: a housing having: an external mounting surface; an internal chamber with an internal surface forming a spherical segment symmetric about a center point; a base end with an assembly opening; and an aperture in a cap end opposite the base end; a stud having: a longitudinal axis passing through the center point; a proximal stud end housed within the internal chamber; and a distal connecting end extending through the aperture, the proximal end having a cylindrical surface and a head laterally extending from the cylindrical surface; and a longitudinally split bearing having: an external bearing surface matching the internal surface of the housing; an internal bearing surface matching the cylindrical surface of the stud; and a longitudinal channel extending radially from the internal bearing surface to the external bearing surface.

TECHNICAL FIELD

The invention relates a split self-aligning snap-in bearing for an automotive rotating joint that enables the joint stud to slide axially, to rotate and to swing through a limited angle thereby providing a self-alignment capacity.

BACKGROUND OF THE ART

Solid axle suspension can suffer from binding or memory steer of the steering joint as a result of misalignment of the supporting rotational joints. The service life of the rotational joints can be reduced due to the increased wear caused by misalignment.

A solid axle suspension, as opposed to independent suspension, is commonly used in larger vehicles such as trucks, vans and sport utility vehicles. The solid axle requires the wheel hub to rotate about an axis to provide steering. Two rotational joints connect a center axle along the rotational axis to the wheel yoke that houses the wheel hub.

The pair of rotational joints that connect the center axle and yoke are usually found in two configurations, namely a pair of conventional ball joints and alternatively a single ball joint combined with a rotating joint that only rotates and can move axially (translate along the rotational axis). Axial motion or translation is required for proper installation to allow movement of the rotational stud when assembling the yoke and center axle together.

The axis of rotation of the stud, in the rotational joint, also determines the axis of rotation of the yoke-center axle assembly. Accordingly the pair of joints must align on the same rotational axis. To allow the yoke to rotate on the center axle, the spherical center of the ball joint must lie on the rotational axis of the rotational joint.

FIG. 1is an exploded isometric view of a prior art automotive solid axle with a suspension center axle1, and yoke2housing the wheel hub3. The center axle1and yoke2are connected at and rotate about a rotational axis4on two rotatable joints5,6.FIG. 2is a schematic sectional view through the prior art center axle1and yoke2along the axis of rotation4, showing a misalignment of the spherical center7of the upper ball joint5and the rotation axis4of the lower rotatable joint6.FIG. 2shows the misalignment as dimension “x”. The misalignment can cause an issue commonly referred to as memory steer.

When the ball joint5and the rotational axis4are misaligned, the rotating joint6experiences forces and stresses which lead to premature failure. To compensate for the misalignment, original equipment manufacturers often use malleable materials such as plastic for bearings to permit a degree of deformation under stress and allow the pair of joints to self-align. The deformation allows the joints to align and mitigates any significant memory steer. However deformation of plastic bearings also shortens the service life of the rotating joint.

Further use of plastic bearings may permit self-alignment under stress, and be less expensive but plastic bearings have a shorter service life than metal bearings in general even without misalignment, and plastic bearings can be easily damaged by high loads, heat and impact.

Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below.

DISCLOSURE OF THE INVENTION

The invention provides a self-aligning rotating joint, for mounting in a first component and connecting to a second component, the rotating joint comprising: a housing having: an external mounting surface; an internal chamber with an internal surface forming a spherical segment symmetric about a center point; a base end with an assembly opening; and an aperture in a cap end opposite the base end; a stud having: a longitudinal axis passing through the center point; a proximal stud end housed within the internal chamber; and a distal connecting end extending through the aperture, the proximal end having a cylindrical surface and a head laterally extending from the cylindrical surface; and a longitudinally split bearing having: an external bearing surface matching the internal surface of the housing; an internal bearing surface matching the cylindrical surface of the stud; and a longitudinal channel extending radially from the internal bearing surface to the external bearing surface.

Further details of the invention and its advantages will be apparent from the detailed description included below.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 3-5show the general arrangement of a self-aligning rotational joint having a spherical longitudinally split bearing8that allows the stud9to swing through a limited angle α relative to the axis of rotation10. The stud9freely rotates about the axis of rotation10and also translates axially relative to the bearing8as described below and indicated with arrows inFIG. 3.

The self-aligning rotating joint has a housing11that is press fit mounted in a first component (such as one of the yoke2or center axle1) and connects to a second component (such as the other of the center axle1or yoke2) using a threaded distal end12of the stud9with a nut (not shown). The housing11includes an abutment flange13extending laterally outward from the external mounting surface14that is press fit into a matching bore in a yoke2or center axle1in a conventional manner. The housing11has a closure plate15disposed in an assembly opening16and a peripheral roll formed edge17that secures the closure plate15also in a conventional manner. The closure plate15seals the interior of the housing11and the bearing8is immersed in lubricant.

The housing11is best seen in isolation inFIG. 9. The external housing features described above include the external mounting surface14, the abutment flange13, the assembly opening16in a base end19of the housing11(without closure plate15and rolled formed edge17seen inFIG. 4) and an aperture18in a cap end20through which the stud9projects (FIGS. 3-5).

As seen inFIG. 9, the housing11has an internal chamber between the assembly opening16and aperture18with an internal surface forming a spherical segment21symmetric about a center point22. The internal chamber has a maximum lateral width along an equatorial plane23of the spherical segment21that passes through the center point22. The internal chamber also includes an assembly portion24between the spherical segment21and the assembly opening16.

The spherical segment21between the equatorial plane23and the inner edge25of the assembly portion24forms a spherical bearing detent surface26which retains the split bearing8in a snap-in progressive installation demonstrated inFIGS. 9 to 11. The assembly portion24as drawn has a conical surface tapering radially inward from the assembly opening16to the inner edge25where the bearing detent surface26begins to open radially outward. A cylindrical surface could be used for the assembly portion24since the spherical surface of the split bearing8serves to compress the bearing8when inserted into the assembly portion24.

FIGS. 6-8show the detailed structure of the longitudinally split bearing8. The split bearing8is preferably made of sintered metal to provide wear resistance and extended service life. However, the split bearing8cold be made of any suitable material such as: ferrous metal; non-ferrous metal; copper; aluminum; tungstenium; sintered metal; rubber compounds; ceramic; polymer; polyacetal; polytetrafluoroethylene (PTFE); graphite; and composites thereof. In the embodiment illustrated the self-aligning split bearing8includes oil distribution grooves32on the internal bearing surface28. Oil distribution grooves32could also be provided on the external bearing surface27if desired.

The bearing8has an external spherical bearing surface27matching the spherical segment21of the internal surface of the housing11. The bearing8has an internal bearing surface28matching the cylindrical surface29(seeFIGS. 4-5) of the stud9. A longitudinal channel30extends radially from the internal bearing surface28to the external bearing surface27and splits the bearing8axially so that the bearing8can flex slightly when compressed laterally.

Referring toFIG. 8, the external bearing surface27of the split bearing8has a maximum lateral width along an equatorial plane31. As seen inFIGS. 4and8, the spherical external bearing surface27extends axially toward the assembly opening16, and extends axially in the opposite direction toward the aperture18.

The longitudinal channel30and the maximum lateral width along the equatorial plane enable the split bearing8to flex slightly as the bearing8is compressed laterally in order to be snap-locked and to be secured into position within the spherical segment21by the bearing detent surface26.FIGS. 9-11show the axial snap-in insertion of the bearing8into the housing11in progressive axial sectional views from left to right. The split bearing8when engaged in the conical assembly portion24of the housing11as shown inFIG. 10, and pressed axially, is compressed laterally as the bearing8slides towards the aperture18. When fully inserted, as shown inFIG. 11, the split bearing8rebounds laterally outward into the spherical segment21which is slightly larger radially than the assembly portion24. The narrowing of the spherical portion between the equatorial plane23and the inner edge25defines the bearing detent surface27that engages and retains the external bearing surface27of the split bearing8.

Referring toFIGS. 3-4, the internal surface28of the bearing8engages the cylindrical surface29of the stud9and with lubricant permits the stud9to rotate and translate axially relative to the housing11. The stud9has a longitudinal axis10passing through the center point22on the equatorial plane of the spherical segment21and split bearing8. As drawn, the proximal stud end33is downward and is housed within the internal chamber of the housing11. The upper or distal connecting end34of the stud is threaded for receiving a connecting nut and extends through the aperture18in the upper or cap end of the housing11. The proximal end33of the stud9has a cylindrical surface29matching the internal bearing surface28of the split bearing8. The proximal end33of the stud9includes a head35laterally extending from the cylindrical surface29to abut the bearing8preventing axial motion in one direction (up as drawn) while space within the assembly portion24of the housing11permits a range of axial motion in the opposite (down) direction. The freedom of axial movement of the head35between the closure plate15and the bearing8enables the stud9to compensate for geometric variance within tolerances for manufacturing and assembly, and to allow the stud9to be assembled into connecting components.

The stud9includes a middle portion36having a conical surface that tapers radially inward from the cylindrical surface29of the proximal end33to the distal connecting end34. The middle portion36could also be cylindrical. As seen in the detail ofFIG. 5, the aperture18in the housing11has a diameter larger than the diameter of the stud9thereby defining an annular clearance gap37surrounding the stud9to allow a predetermined angle α of roll and pitch movement of the stud9.

The roll and pitch movement of the stud9in the direction indicated with angle α is permitted by the interaction between the spherical external bearing surface27and the spherical segment21of the housing11. Roll and pitch about the center point22allows the rotating stud9to self-align thereby avoiding the misalignment “x” with a companion ball joint5indicated inFIG. 2. Accordingly, the movement through angle α allows the rotating bearing to self-align with the companion ball joint and eliminate the disadvantages of memory steer.

Although the above description relates to a specific preferred embodiment as presently contemplated by the inventors, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein.