Internally sealed pivotal joint assembly

Abstract: An internally sealed pivotal joint assembly for use on buses and other vehicles is provided. The assembly includes an eyelet (12) which has disposed therein a bearing socket (18) for positioning a ball stud journal (24) therein. The assembly includes a cap (36) and a sealing ring provided to the socket (18) in order to avoid ingestion of contaminants and obviate the need for repeated lubrication of the assembly.

Description: Background of the Invention This invention relates to an internally sealed pivotal joint for link assemblies used in connection with, for example, sway bars or steering links for vehicles and for torque rods. The invention includes an assembly having an eyelet into which a bearing socket with an internal seal is disposed. A ball stud journal is positioned within the bearing socket to form the assembly. Such internal seals are protected from external physical damage and could be an integral part or a separate component of the bearing socket. The assembly is capped to avoid ingestion of contaminants into the assembly. While the invention is particularly directed to the art of corrosion repellant, lubricated-for-life pivotal joints and link assemblies for vehicles, and will thus be described with specific references thereto, it will be appreciated that the invention may have usefulness in other fields and applications. Briefly, with exemplary reference to Figure 8, buses -- while having a variety of configurations -- typically have a front suspension A which includes, among other things, a sway bar B and a frame C. Conventionally, a link D is used to connect the sway bar B and the frame C. However, this pivotal joint design allows for collection of contaminants in the link D because the pivotal joints in link D are not sealed, causing premature field failures. The link D also requires periodic reapplication of lubricant. In addition, high slip torque between bearing surfaces will generate internal heat and shorten the life of the joint. The front suspension of buses also typically includes a steering link E having connected thereto a ball stud assembly F which is connected to a spindle assembly G. This type of connection, having an exterior sliding umbrella seal, provides limited protection. Furthermore, it is exposed to external elements and prone to impact induced cuts from stones and the like, thus preventing an efficient and reliable operation thereof. There are more sophisticated exterior boot type seals used in the industry that consist of several components and require a complex manufacturing process; however such seals provide no protection from exterior physical damage. For example, these designs are prone to exterior damage e.g. impact damage. In addition, boot type seals are prone to flex fatigue induced cracks and wear failures. It should be noted that vehicle chassis environmental conditions are extremely hostile. Consequently, the seal is an important component of any pivotal joint subject to this environment. The performance of the seal affects the function and reliability of the pivotal joint, and therefore, the function and reliability of the linkage system, e.g. steering, suspension, etc. Figure 1 of FR-A-1 091 445 discloses a bearing arrangement in which an eyelet has an aperture extending therethrough. A bearing socket is provided in the eyelet's aperture. The bearing socket is open at its first and second opposite ends. The inner surface of the bearing socket is provided with a plurality of dimples, as is the cylindrical exterior surface of the bearing socket. A ball stud journal is provided having its ball end received within the bearing socket. The stud end of the ball stud journal extends through an opening in one end of the eyelet. The opening in the other end of the eyelet is closed by a cap. The stud end of the ball stud journal is provided with an elastic joint to contact the exterior surface of the eyelet when the stud end of the ball stud journal moves in the bearing with respect to the eyelet. US-A-3 848 938 discloses a bearing having two relatively moveable parts, with one of them having an arcuate outer surface. A seal, having three sealing edges, is used to entrap lubricant and keep out water and dirt. Each of the three sealing edges contacts the moveable member having the arcuate surface, thereby providing two voids to entrap lubricant to lubricate the ceiling edges and to provide additional sealing. GB-A-2 170 265 discloses a ball and socket joint having a ball held in the inner space of a housing. Two bearing shells are provided between the joint housing and the ball. Two resilient plastics material pressure rings are in contact with the bearing shells. The bearing shells have conical surfaces engaging the pressure rings. According to a first aspect of the present invention there is provided an assembly comprising: a link including a first eyelet having a first aperture extending therethrough and a second eyelet having a second aperture extending therethrough; a first single piece bearing socket having a first generally spherical inner contour disposed in the first eyelet, the first inner contour being closed at a first end of the first aperture by the single piece nature of the first socket, the first inner contour having an opening defined by an integral internal annular seal ring proximate to a second end of the first aperture, the first inner contour having a first plurality of dimples positioned thereon; a first ball stud journal having a ball end thereof disposed in the first socket in sliding contact with the first inner contour, the first ball stud journal having a first stud end thereof extending through the opening of the first socket and the second end of the first aperture, the first stud end being capable of angular movement with respect to the first eyelet in first and second mutually perpendicular planes due to the sliding contact between the first ball stud journal and the first inner contour, a first cap positioned in the first end of the first aperture to secure and seal the first socket and the first ball stud journal in the first eyelet; a second single piece bearing socket having a second generally spherical inner contour disposed in the second eyelet, the second inner contour being closed at a first end of the second aperture by the single piece nature of the second socket, the second inner contour having an opening defined by an integral internal annular seal ring proximate to a second end of the second aperture, the second inner contour having a second plurality of dimples positioned thereon; a second ball stud journal having a ball end thereof disposed in the second socket in sliding contact with the second spherical inner contour, the second ball stud journal having a second stud end thereof extending through the opening of the second socket and the second end of the second aperture, the second stud end being capable of angular movement with respect to the second eyelet in first and second mutually perpendicular planes due to the sliding contact between the second ball stud journal and the second inner contour and, a second cap positioned in the first end of the second aperture to secure and seal the second socket and the second ball stud journal in the second eyelet. Embodiments of apparatus in accordance with the present invention will now be described by way of example only, with reference to the accompanying drawings, described below. FIGURE 1 is a cross-sectional view of a pivotal joint assembly suitable for use in the assembly of the present invention. FIGURE 2 is a cross-sectional view of an elastomeric bearing socket suitable for use in the pivotal joint assembly of FIGURE 1. FIGURE 3 is a cross-sectional view of an alternative elastomeric bearing socket suitable for use in the pivotal joint assembly of FIGURE 1. FIGURE 4 is a cross-sectional view of a ball stud journal suitable for use in the assembly of the present invention. FIGURE 5 is a cross-sectional view along the line 9-9 of FIGURE 4. FIGURE 6 is a partial cross-sectional view of a first embodiment of link assembly in accordance with the present invention. FIGURE 7 is a partial cross-sectional view of a second embodiment of link assembly in accordance with the present invention. FIGURE 8 is a partial exploded view of an exemplary bus front suspension. Detailed Description of the Preferred Embodiment Referring now to the drawings wherein the showings are for purposes of illustrating the preferred embodiments of the invention only and not for purposes of limiting same, Figure 1 provides a view of a preferred embodiment. As shown, the joint assembly 10 has an eyelet 12 . The eyelet 12 has an aperture 14 . An elastomer bearing socket 18 is positioned within the aperture 14 and has a closed end proximate to a first end 20 of the aperture 14 and an open end proximate to a second end 22 of the aperture 14 . Also shown is a ball stud journal 24 having a ball end 26 and stud end 28 . The ball end 26 preferably comprises a metal ball portion 30 having plastic 32 or other compatible (with bearing socket) corrosion resistant bearing material coating. It is recognized that suitable, alternative materials other than plastic may be used. The stud end 28 , preferably formed of metal, includes a threaded portion 34 . A metal cap 36 is positioned in the first end of the eyelet 12 in order to secure the bearing socket 18 and ball stud journal 24 in the eyelet 12 . The cap 36 , which is secured to the eyelet by known techniques, also provides sealing for the assembly to avoid ingestion of contaminants therein. Plastic thread protectors 38 are provided to the threaded portion 34 . The thread protectors 38 are particularly useful during transportation and shipping of the link assemblies. Ultimately the threaded portion is used to secure the link assembly to various other assemblies such as a sway bar and a frame. The eyelet 12 is preferably formed of metal, although other suitable materials of sufficient strength may be used. The eyelet 12 facilitates bearing socket and ball stud sub-assembly insertion into the aperture 14 from the first end 20 and has a bearing socket seat 21 at the second end 22 . The bearing socket seat 21 prevents socket and/or ball stud disengagement through the aperture opening. The socket 18 is preferably formed of polyurethane processed by injection molding or other suitable process to achieve maximum performance but any appropriate, compatible (with journal), corrosion resistant bearing material will suffice. Referring now to Figure 2 , the bearing socket 18 has an integral annular ring projection 50 disposed around its open end. The ring projection 50 is compressed against the spherical portion of the journal 24 and provides for sealing when the ball stud journal is positioned therein. The sealing ring 50 prevents ingestion of contaminants and seals lubricant within the assembly. In addition, the bearing socket 18 has a generally spherical inner contour 52 having lubricant reservoirs that are exemplary shown as dimples at 54 formed thereon. The dimples or other cavity configurations -- such as a waffle pattern or annular grooves -- provide a plurality of lubricant reservoirs to facilitate continuous supply of lubricant onto the sliding surfaces between the ball stud journal 24 and the bearing socket 18 facilitating prolonged product performance. Preferably, a silicone based or other suitable bearing lubricant is used for this purpose. However, the bearing socket also could be made from engineered low coefficient friction, abrasion resistant elastomeric or plastic material containing lubricant within, compounded into the material. FIGURE 3 illustrates a further embodiment of the invention utilizing a different integral seal ring design. In this regard, a stress relief groove 56 is formed adjacent the annular seal ring 50 . This groove facilitates increased seal ring compression capability, preventing excessive stress imposed on the seal ring 50 . The increased seal compression in turn will assure appropriate seal function at higher bearing socket deflections generated by external operational loads exerted on the linkage. In addition, the groove 56 provides reduced stress on the seal ring 50 when assembled and better material distribution -- a part of the seal ring is displaced in the groove and another part of the ring is displaced toward the end 22 . FIGURES 4 and 5 illustrate the ball stud journal 24 , preferably made from metal or other high strength material. The semi-spherical portion, or ball end, 26 is coated with high finish, corrosion repellant compatible plastic or like bearing material 32 . The ball end surface configuration has grooves 27 that receive the plastic coating to facilitate bonding and locking between the plastic 32 and the ball end 26 . It is to be appreciated that various surface configurations could be implemented to achieve such bonding and locking. Chemical adhesion material could also be used to facilitate bonding and locking between the two elements. Instead of or in addition to a plastic coating, surface protection of the spherical ball end could also be achieved through electrolytic or electroless plating of suitable corrosion resistant bearing materials, e.g. hard NI, chrome etc. A variety of uses of the assembly 10 are contemplated but a typical application is shown in Figure 6. As illustrated, the assembly 10 is connected to an identical assembly 10' by a link, or bar, 16 . This configuration is then useful to replace the link D shown in Figure 8. It should be noted that identical elements are hereinafter identified by primed numerals. Figure 7 illustrates a still further alternative embodiment of the present invention. More particularly, an adjustment assembly 60 may be provided in place of the bar 16 shown in Figure 6. In this case, a link arm 62 ( 62' ) extends from eyelet 12 ( 12' ). A threaded portion 64 is provided to the link arm 62 . A sleeve 66 receives the threaded portion 64 in threaded 20 receiving portion 68 . A recess, or cut-out, 70 is formed in the sleeve 66 along the threaded receiving portion 68 to facilitate clamping of the sleeve 66 by clamp 72 so that once the sleeve 66 is threaded onto the link arm 62 , the link arm 62 can be locked in place relative to the sleeve 66 . The clamp 72 can be any conventional C-clamp or the like. In the preferred embodiment, clamping and/or tightening is accomplished through manipulation of bolt 74 . Also illustrated in Figure 7 is a stop surface 76 which prevents the link arm 62 from being threaded beyond a predetermined point within the sleeve 66 . Accordingly, the spacing between the eyelets may be selectively adjusted by threadably advancing or retracting the link arms in the sleeve. It is to be appreciated that this embodiment of the invention is useful to replace the ball stud assembly F of Figure 8.

Claims: An assembly comprising: a link including a first eyelet (12) having a first aperture (14) extending therethrough and a second eyelet (12') having a second aperture extending therethrough; a first single piece bearing socket (18) having a first generally spherical inner contour (52) disposed in the first eyelet (12), the first inner contour (52) being closed at a first end (20) of the first aperture (14) by the single piece nature of the first socket, the first inner contour having an opening defined by an integral internal annular seal ring (50) proximate to a second end (22) of the first aperture (14), the first inner contour (52) having a first plurality of dimples (54) positioned thereon; a first ball stud journal (24) having a ball end (26) thereof disposed in the first socket (18) in sliding contact with the first inner contour, the first ball stud journal (24) having a first stud end (28) thereof extending through the opening of the first socket (18) and the second end (22) of the first aperture (14), the first stud end (28) being capable of angular movement with respect to the first eyelet (12) in first and second mutually perpendicular planes due to the sliding contact between the first ball stud journal (24) and the first inner contour (52), a first cap (36) positioned in the first end (20) of the first aperture (14) to secure and seal the first socket (18) and the first ball stud journal (24) in the first eyelet (12); a second single piece bearing socket having a second generally spherical inner contour disposed in the second eyelet (12'), the second inner contour being closed at a first end of the second aperture by the single piece nature of the second socket, the second inner contour having an opening defined by an integral internal annular seal ring proximate to a second end of the second aperture, the second inner contour having a second plurality of dimples positioned thereon; a second ball stud journal having a ball end thereof disposed in the second socket in sliding contact with the second spherical inner contour, the second ball stud journal having a second stud end (28') thereof extending through the opening of the second socket and the second end of the second aperture, the second stud end being capable of angular movement with respect to the second eyelet in first and second mutually perpendicular planes due to the sliding contact between the second ball stud journal and the second inner contour and, a second cap (36') positioned in the first end of the second aperture to secure and seal the second socket and the second ball stud journal in the second eyelet (12'). An assembly as claimed in claim 1, further comprising a bar (16) connected between the first and second eyelets. An assembly as claimed in claim 1, further comprising an adjustment assembly (60) connected between the first and second eyelets (12, 12'), the adjustment assembly comprising threaded end portions (64, 64') extending from the first and second eyelets that are received in a threaded sleeve (66) whereby a length of the link is adjustable. An assembly as claimed in any one of the preceding claims, wherein the first and second ball stud journals (24) each comprise a metallic ball stud having plastic (32) moulded around the ball end (26) thereof. An assembly as claimed in any one of the preceding claims, wherein the first and second bearing sockets (18) are formed of polyurethane. An assembly as claimed in any one of the preceding claims, further comprising lubricant provided to the first and second bearing sockets (18) to provide a film between the first and second bearing sockets and the first and second ball stud journals (24), respectively, to reduce friction therebetween. An assembly as claimed in any one of the preceding claims, further comprising relief grooves (56) adjacent the integral seal (50) rings.

Inventors: JAWORSKI KEVIN J, LUZSICZA STEVEN, JAWORSKI, KEVIN J, LUZSICZA, STEVEN
Applicants: PULLMAN CO, THE PULLMAN COMPANY
Application year: 1997
Main classification: B62D7
IPC codes: B62D7, B60G7, B60G21