Patent Application
20090003743
Single acting/angular contact spherical plain bearings are designed to support heavy unidirectional thrust and combination radial/thrust loads. Typically, such bearings comprise an inner ring and an outer ring, and the outer ring forms a concave spherical bearing surface that has a large bore opening and a small bore opening. The inner ring has a convex spherical bearing surface sized and configured to engage the outer ring bearing surface. The inner ring may have an interior shaft-engaging surface to engage a rotating and/or pivoting shaft therein.
The outer ring bearing surface is symmetric about a central axis and increases in diameter from the small bore opening to the large bore opening. Accordingly, the inner ring is typically separable from the outer ring by removal via the large bore opening unless it is secured in the outer ring by an accessory structure.
The outer ring typically has a lubrication groove in the concave interior bearing surface and a lubrication aperture that extends through the outer ring, from the exterior surface of the outer ring to the lubrication groove. Typically, the outer ring of the bearing is secured in a housing, and there is a housing lubrication aperture that communicates with the outer ring lubrication aperture. Lubricant can be injected into the bearing load zone (the interface of the bearing surfaces of the inner and outer rings) via the housing lubrication aperture and the outer ring lubrication aperture. In addition, there may be an axial lubrication groove (a “break-out” groove) in the concave bearing surface of the outer ring. The break-out groove communicates with the small bore opening of the outer ring. Lubricant may then be added to the load zone by injecting lubricant into to the small bore opening of the outer ring. The bearing may have a plate at the small bore opening to seal the opening and contain the lubricant provided via the outer ring lubrication aperture or via the shaft. A shaft in the bearing may be equipped with a lubrication aperture through which lubricant is supplied to the small bore opening. Using this configuration, the lubricant would flow through the shaft and deflect back into the bearing via the break-out groove. However, these methods of providing lubricant are sometimes ineffective due to the long and/or convoluted path of travel that the lubricant must traverse to reach the lubrication channel.
Based on the foregoing, it is the general object of this invention to provide a bearing and a method of lubrication that improves upon, or overcomes the problems and drawbacks of prior art bearings.
The present invention resides in one aspect in a shaft and bearing assembly that includes a shaft mounted in a spherical plain bearing. The spherical plain bearing includes an outer ring and an inner ring disposed within the outer ring. The inner ring has a first bearing surface and an interior shaft-engaging surface, the first bearing surface having a convex spherical configuration. The inner ring is mounted on the shaft. The outer ring has a second bearing surface that engages the first bearing surface. There is a first inner ring lubrication groove on the first bearing surface of the inner ring, as well as an inner ring lubrication aperture that extends from the first inner ring lubrication groove to the shaft-engaging surface. The shaft comprises a shaft lubrication aperture that communicates with the inner ring lubrication aperture.
The present invention resides in another aspect in a kingpin linkage assembly that includes a steering knuckle and an axle yoke pivotably interconnected with the steering knuckle by two kingpin-bearing assemblies. The kingpin-bearing assembly includes a kingpin and an associated spherical plain bearing. Each spherical plain bearing comprising an outer ring and an inner ring disposed within the outer ring, with the kingpin being mounted in the inner ring. The inner ring has a first bearing surface and an interior shaft-engaging surface, and the outer ring has a second bearing surface. The first bearing surface has a convex spherical configuration and the second bearing surface has a concave spherical configuration. The second bearing surface slidability engages the first bearing surface. There is a first inner ring lubrication groove on the first bearing surface and an inner ring lubrication aperture that extends from the first inner ring lubrication groove to the shaft-engaging surface. The kingpin includes a kingpin lubrication aperture that communicates with the inner ring lubrication aperture.
Another aspect of the invention resides in a method of lubricating a bearing and shaft assembly as described herein. The method includes flowing lubricant through the shaft lubrication aperture, through the inner ring lubrication aperture, and into the first lubrication groove.
One illustrative embodiment of an inner ring for a single-acting spherical plain bearing according to this invention is shown in
The inner ring 10 is shown as having one inner ring lubrication groove 16, one interior lubrication groove 18 and two inner ring lubrication apertures 20, but the invention is not limited in this regard, as in alternative embodiments there may only be one inner ring lubrication aperture or there may be more than two such apertures. There may also be more than one inner ring lubrication groove 16 and/or more than one interior lubrication groove.
A spherical plain bearing comprising the inner ring 10 of
The outer ring 24 is shown as having one outer ring lubrication groove 32, one outer ring lubrication aperture and one optional break-out lubrication groove, but the invention is not limited in this regard, as in alternative embodiments there may only be more than one outer ring lubrication groove, and/or more than one outer ring lubrication aperture, and/or, optionally, more than one optional break-out lubrication groove.
In still other embodiments, there may be a break-out lubrication groove on the convex bearing surface of the inner ring.
The bearing 22 provides a direct path for providing lubricant to the bearing load zone. This is accomplished by use of aperture 20 in the inner ring 10. Lubricant can be introduced into the bearing spherical raceway or load zone through a shaft mounted in inner ring 10, as described elsewhere herein.
One embodiment of the bearing 22 combined with a shaft 40 mounted therein is shown in
The load zone of the bearing 22 can be lubricated by injecting lubricant through an inner ring lubrication aperture 20, via the shaft lubrication aperture 46. Lubricant will flow through the shaft 40 and will enter the bearing via one or both of a radial lubrication outlet 46a and an axial lubrication outlet 46b. The lubricant will flow through the inner ring lubrication aperture 20 (optionally by way of the inner ring inner lubrication groove 18) to the load zone where it will be distributed via the inner ring lubrication groove 16 and/or the outer ring lubrication groove 32. This is an effective and efficient means of bearing lubrication and it also provides a secondary lubricant flow path when used in conjunction with prior art lubrication methods such as supplying lubrication to the outer ring small bore via the break-out lubrication groove.
In a specific embodiment of a shaft and bearing assembly 39, the shaft may be a kingpin 56 or 58 (
The bearings 22 are mounted in respective mounting portions 54a, 54b of the axle yoke 54 and the outer rings 24 may be fixedly secured to the axle yoke. Each kingpin 56, 58 has a respective journal portion 56a, 58a that passes through a respective kingpin aperture 52a in the steering knuckle 52 and engages the bore 14a of the inner ring 10 of the associated bearing 22. In the illustrated embodiment, the journal portions 56a, 58a include reduced diameter end portions that fit into the inner rings 10 of the respective bearings 22. However, the invention is not limited in this regard, and in the exercise of ordinary skill in the art, various sizes and configurations of journal portions on the kingpins can be matched with bearings. Each kingpin 56, 58 comprises a mounting portion 56b, 58b by which the kingpin is fixedly secured to the steering knuckle 52. For example, each kingpin 56, 58 may have a respective head portion 56b, 58b that may be attached to the steering knuckle 52 by one or more bolts 60a, 60b that extend through the head portions to the steering knuckle. However, the invention is not limited in this regard as numerous other mounting configurations will occur to one of ordinary skill in the art, e.g., the kingpins 56 and/or 58 may have fitted portions 56c, 58c that are keyed in respective apertures in the steering knuckle 52. The kingpins 56, 58 may be equipped with lubrication apertures 62, 66 and lube fittings 64a, 64b to lubricate their respective bearings as described in relation to
To assemble the kingpin linkage assembly 50, the outer rings 24 are installed in the axle yoke 54 and the inner rings 10 are pressed onto the kingpins 56, 58. The steering knuckle 52 is aligned with the axle yoke 54 and the kingpins (with inner rings 10 mounted thereon) are then inserted through the apertures 52a in the steering knuckle and into the axle yoke where the inner rings then mate with the outer rings 24. The assembly process is completed by bolting the kingpins 56, 58 to the steering knuckle 52 with bolts 60a, 60b.
In use, a driver rotates a steering wheel (not shown) that is connected to the steering knuckle 52 via tie rods (not shown). The kingpin linkage assembly allows the steering knuckle 52 and a wheel hub thereon to pivot relative to the axle yoke 54 and axle 55. Thus, the driver turns the vehicle wheels.
While
The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. In addition, the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.
Although the invention has been described with reference to particular embodiments thereof, it will be understood by one of ordinary skill in the art, upon a reading and understanding of the foregoing disclosure, that numerous variations and alterations to the disclosed embodiments will fall within the scope of this invention and of the appended claims.
This application claims the benefit of U.S. provisional application No. 60/937,405 filed Jun. 26, 2007, which is hereby incorporated herein by reference, in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60937405 | Jun 2007 | US |
