Patent Application
20180045243
The present invention relates to an encapsulated bearing assembly, and, more particularly, to an encapsulated bearing assembly having an internal damping layer.
Axial roller bearings are used in various applications, including automotive assemblies such as drivetrain and suspension components, to distribute loads and allow for relative rotation. These include thrust bearings, which are positioned adjacent to a component in order to carry an axial load exerted by that component. Thrust and other axial roller bearings are often encapsulated in that they include a plurality of rollers enclosed by an opposing pair of washers. The rollers are positioned in a cage and directly contact races formed by inner surfaces of the washers. While this is a typical bearing configuration, it may be less than ideal in certain situations because the direct contact between all components allows the bearing to transmit vibration from one side to the other, and to adjacent components, fairly easily. For example, a typical thrust bearing may transmit vibration to a transmission case, which may then lead to undesirable noise being produced from the case.
Excessive vibration can be inhibited by preventing surface defects in the rollers and races of the bearings. However, ensuring that all components are made without even minor defects is cost prohibitive and generally not feasible. Another potential solution is to include an external damping layer between the bearing and the adjacent component, such as in the configuration described in U.S. Patent Application No. 2011/0182542. A drawback of the external damping layer, however, is that it may wear due to rotation of the bearing relative to the adjacent component.
It would therefore be desirable to provide an axial roller bearing which addresses the problem of edge loading and other drawbacks of the prior art.
In one aspect, the present disclosure is directed to an axial roller bearing assembly. The axial roller bearing assembly includes a first axial washer including a first race surface and a second axial washer including a thrust surface. The first axial washer and the second axial washer form a housing space. The axial roller bearing assembly also includes a third axial washer disposed in the housing space between the first axial washer and the second axial washer and including a second race surface. The axial roller bearing assembly further includes a bearing element disposed in the housing space and which includes a cage and a plurality of rollers in contact with the first race surface and the second race surface. The axial roller bearing assembly also includes a damping layer disposed in the housing space and in contact with the second axial washer and the third axial washer. The damping layer inhibits vibration from transferring between the third axial washer and the second axial washer.
The foregoing Summary and the following detailed description will be better understood when read in conjunction with the appended drawings, which illustrate a preferred embodiment of the invention. In the drawings:
The first axial washer 12 includes a circumferentially extending body 22 which includes an axial flange 24 and a radial flange 26. The axial flange 24 extends axially and forms an enclosing surface 28. The radial flange 26 is directly connected to and extends in an outward-radial direction from the axial flange 24. The radial flange 26 defines an outer thrust surface 30 and an inner race surface 32 (i.e. a first race surface). In an exemplary embodiment, the axial flange 24 and radial flange 26 form an L-shaped cross-section, with the axial flange 24 extending in a first axial direction (e.g., toward the transmission case 100) at a radially-inner section of the bearing assembly 10.
The second axial washer 14 includes a second circumferentially extending body 34 which includes an axial flange 36 and a radial flange 38. The axial flange 36 extends axially and forms an enclosing surface 40. The radial flange 38 is directly connected to and extends in an inward radial direction from the axial flange 36. The radial flange 38 defines an outer thrust surface 42 which, in an exemplary embodiment, is in contact with the transmission case 100. The radial flange also includes an inner surface 44. In an exemplary embodiment, the axial flange 36 and the radial flange 38 form an L-shaped cross-section, with the axial flange 36 extending in a second axial direction, which is opposite to the first axial direction (e.g., away from the transmission case 100) at a radially-outer section of the bearing assembly 10.
As shown in
The third axial washer 16 is positioned in the housing space 46, between the bearing element 18 and the damping layer 20, and includes a race surface 48 (i.e., a second race surface) and a damping surface 50.
The bearing element 18 is preferably an axial needle roller arrangement, although other types of bearing elements are possible. In an exemplary embodiment, the bearing element 18 includes a plurality of rollers 52 which are spaced apart circumferentially from one another by a cage 54. The rollers 52 and cage 54 may be preassembled as a cage and roller assembly that includes the rollers 52 located in pockets in the cage 54, which is preferably stamped from sheet metal. The rollers 52 are located in at least some of the pockets and roll against the inner race surface 32 of the first axial washer 12 on one side and the race surface 48 of the third axial washer 16 on the opposite side. A lubricant may be positioned in between the race surfaces 32, 48 and the rollers 52. An axial force exerted on the bearing assembly 10 may help to maintain the rollers 52 in contact with the race surfaces 32, 48, which may help to ensure proper operation of the bearing assembly 10.
In order to connect the components of the bearing assembly 10, the first axial washer 12 and the second axial washer 14 preferably include interlocking features. For example, the first axial washer 12 and the second axial washer may include punch-in tabs 56 which overlap and/or are inserted into opposing portions of the cage 54. This interlocking connection retains the bearing element 18 within the first axial washer 12 and the second axial washer 14. Alternative means for interconnecting the components include external fasteners, an overlap of interlocking features on the axial washers themselves etc.
The damping layer 20 is positioned between and in contact with the inner surface 44 and the damping surface 50. The damping layer 20 is made of a vibration-reducing material which isolates the bearing element 18 from the second axial washer 14 and the transmission case 100. For example, the damping layer 20 may be formed from a polymer material having good sound and vibration damping qualities. Examples of materials that may be used for damping layer 20 include nitrile butadiene rubber (NRB), fluoroelastomers which contain vinylidene fluoride monomers, and acrylic. The damping layer 20 may include a hardness of approximately 50-75 durometer. In some embodiments, the damping layer 20 may include a thin steel core coated with a damping material, such as one of the materials listed above.
In an exemplary embodiment, the damping layer 20 is formed to be a flat ring-shaped component. For example, the damping layer 20 may include an axial thickness that is much less than a radial length (i.e., the radial dimension of the cross-section of the damping layer 20 shown in
Moreover, the damping layer 20 is formed to be in surface contact with the second and third axial washers 14, 16. For example, the opposing surfaces of the damping layer 20 may be in surface contact with the inner surface 44 and the damping surface 50. In some embodiments, in order to sufficiently decouple the second and third axial washers 14, 16, the damping layer 20 may contact at least 80% of a surface area of the inner surface 44 and the damping surface 50.
In use, the damping layer 20 inhibits the transfer of vibration from the third axial washer 16 to the second axial washer 14 and the adjacent transmission case 100 (and vice versa). In this way any vibration produced by the bearing element 16 (or another component in contact with the first axial washer 12) will be inhibited from causing the transmission case 100 to vibrate, thereby reducing the potential for the transmission case 100 to produce excessive noise and/or be damaged. Similarly, any vibration originating in the transmission case 100 (or other component in contact with the thrust surface 30) will not transfer through the bearing assembly 10.
Further, the interlocking connection with the cage 54 insures that the first and second axial washers 12, 14 remain decoupled from each other in terms of vibration-transmission. Vibration that occurs due to the rollers 52 will primarily be localized to the first and third axial washer 12, 16, and does not transfer easily through the cage 54. Therefore, despite the close positioning and interconnection of an encapsulated bearing, the disclosed configuration nevertheless allows such a bearing to inhibit the transfer of vibration from one side to another. In this way, such encapsulated bearings may be used in conjunction with components (i.e., transmission case 100) that are susceptible to vibration and/or on which vibration has a negative effect.
Having thus described various embodiments of the present bearing assembly 10 in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description above, could be made in the assembly without altering the inventive concepts and principles embodied therein. For example, in some embodiments, the components may be reversed, with the third axial washer 16 and the damping layer 20 positioned on an axially-outer side of the bearing element 18 and the second axial washer 14 defining a race surface in contact with the rollers 52. Moreover, the axial flanges 24, 36 may be reversed, with the axial flange 24 forming a radial-outer support surface and the axial flange 36 forming a radial-inner support surface.
The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.
