Retained polymer bushing bearing

Details Retained polymer bushing bearing Retained polymer bushing bearing

2001-11-13

2004-05-04

Joyce, William C. (Department: 3682)

Bearings

Rotary bearing

Plain bearing

C384S906000

Reexamination Certificate

active

06729765

ABSTRACT:

FIELD OF THE INVENTION
This invention is directed generally to bearing assemblies, and more particularly bushing bearings.
BACKGROUND
Bearing assemblies often include various components including rolling elements that are retained within the assembly to reduce friction and wear between moving parts or surfaces. In some bearing assembly applications, a bushing is used in place of rolling elements to eliminate the necessity for the rolling elements, grease, and retainer. The bushing usually exhibits self-lubricating and shock absorbing properties allowing the bearing to run smoothly and quietly. Often the bushing is made up of a polymer such as Polytetrafluoroethylene (PTFE).
The bushing is often press-fitted inside the bearing assemblies housing, and the bushing is retained by the pressure of the press-fit. In high pressure applications, or in applications where high temperatures are experienced, the bushing will creep during its useful life and the press-fit pressure may be lost. This may result in the bushing rotating within the bearing housing. Other conditions, may also cause the bushing to undesirably rotate within the housing leading to reduced bearing or bushing life.
To prevent any relative movement between the bushing and the housing, some have attempted to use an adhesive to positively lock the bushing within the housing. However, over time and under high temperature, the adhesive has been found to degrade and the bushing may either undesirably come out of the housing, or rotate within the housing. Such methods and results are unacceptable and consequently lead to reduced bearing life and machine downtime.
Another method for retaining the bushing within the housing has been to provide a circumferential groove within the housing and to provide a corresponding bumper on the outer diameter of the bushing. Sometimes this method has been used in connection with an adhesive. In this manner, the polymer bushing is snap fit into the circumferential groove within the housing and retained within the housing. This method may prevent the bushing from moving axially with respect to the housing. However, it does not prevent the bushing from rotating, or spinning within the housing when the adhesive degrades.
Thus, there is a need in the art to provide a bushing that will remain positively retained within the housing.
SUMMARY
The present embodiment is specifically directed to a bushing positioned within a housing that is positively retained to prevent the bushing from moving axially with respect to the housing and that also prevents the bushing from rotating relative to the housing. The present embodiment utilizes a retention pin that positively retains the bushing within the housing.
In an aspect of the present embodiment, a bushing is mechanically locked within a housing to reduce movement of the bushing in axial and circumferential directions relative to the housing. In an exemplary embodiment, a bearing assembly includes at least one retention pin that mechanically locks the bushing within the bearing housing.
In another aspect of the present invention, a locking pin retains an inner ring positioned within an outer ring. The locking pin retains the inner ring from rotating in relation to the outer ring in an axial and circumferential direction. In the exemplary embodiment, the inner ring includes a polymer bushing, and the outer ring includes a housing.
The present embodiments can be utilized in bearings that may be exposed to harsh operating conditions, including subjection to high temperatures and pressure. They provide the ability to retain a bushing within a housing. Consequently, movement of the bushing is reduced in an axial and circumferential direction relative to the housing.
The foregoing and other objects, features and advantages of the bearing or bearing assembly will be apparent from the following more particular description of preferred embodiments as illustrated in the accompanying drawings.


REFERENCES:
patent: 1859608 (1932-05-01), Vigne
patent: 2988405 (1961-06-01), Scheldorf
patent: 3400988 (1968-09-01), Hudson
patent: 4800057 (1989-01-01), Rabe
patent: 5209577 (1993-05-01), Swatek
patent: 297 01 634 (1997-05-01), None
A program of Continuing Engineerng Education course on self-lubricated non-metallic bearings conducted by the University of Wisconsin, Milwaukee, Feb. 16-17, 1999.

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