Patent Application
20110262065
The present invention relates to a shaft bearing assembly.
In a variable speed belt drive a belt pulley sheave is axially slidable on a shaft.
Bearings are required to prevent wear between the relatively movable parts. There are many low friction bearings/bushings commercially available to prevent wear between two moving parts. The available bearings require either a press fit to one part or a flange at either end to hold the bearing in position. Press fit bearings require tight tolerance control in machining and must have clearance holes larger than the bearing outer diameter to position the bearing in the press fit bore. Bearings with flanges at each end require extra axial length in the design and the flange part provides limited support because it is not backed up.
Accordingly, an object of this invention is to provide a bearing assembly which does not require a press fit.
A further object of the invention is to provide such a bearing assembly which does not require tight tolerance control in machining.
These and other objects are achieved by the present invention, wherein a bearing assembly movably supports a component on a shaft. The bearing assembly includes a pair of annular bands which are spaced apart axially and which project radially inwardly from the component. The bands form an annular slot therebetween. An annular bearing member is mounted on the shaft. The bearing member has a larger diameter central flange and a pair of smaller diameter rings projecting axially from opposite sides of the central flange. The central flange is received by the slot, and each ring is positioned between the shaft and a respective one of the bands. The bearing member has a T-shaped cross-sectional shape.
Referring to
An annular cylindrical bearing member 30 is mounted on the shaft 12. The bearing member 30 has a larger diameter central flange 32 and a pair of smaller diameter rings 34 and 36 projecting axially from opposite sides of the radially inner portion of the central flange 32. The central flange 32 is received by the annular slot 24. Each ring 34, 36 is positioned between the shaft 12 and the inner surface 20, 22 of a respective one of the band members 16, 18. The bearing member 30 has a T-shaped cross-sectional shape in a plane which contains an axis of the shaft 12.
The base material of the bearing member 30 can be polymeric, fibrous, or metallic. The bearing material may have additives to modify the properties of the bearing. The bearing member 30 should have sufficient flexibility and spring rate that it can be wrapped over itself or folded in on itself during installation and returned to its circular form in the assembly without damage. The bearing member 30 may be split, such as at 38, from the inner diameter to the outer diameter so it can be wrapped on itself to ease installation. The split may be any width or angle necessary to install the bearing member 30.
With this bearing assembly 10, the machining tolerances can be larger because a press fit is not required to keep the bearing member 30 in place. The T-shape of the bearing member 30 minimizes the working axial distance used in the assembly 10 and allows for a more axially compact design. The flexible nature of the bearing material allows it to be manipulated to fit though a smaller hole than a press fit bearing would fit through during assembly. Backup rings and snap rings can be eliminated from the assembly.
Preferably, a conventional seal assembly 40 is mounted adjacent to the bearing assembly 10 between the shaft 12 and the component 14.
While the present invention has been described in conjunction with a specific embodiment, it is understood that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of the appended claims.
