Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
1999-11-19
2001-08-07
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S906000
Reexamination Certificate
active
06270260
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to bearings and methods of preventing bearing outer race creepage. One prior art embodiment utilizes a ball bearing which is welded to the outer race of the bearing. The bearing is installed in a lead-end bracket housing. A tab is assembled to the bracket housing adjacent to the bearing cavity via a self-tapping screw. Since the bearing on this prior art design is recessed below the surface of the bearing cavity hub and the tab, the ball, which is attached to the outer bearing race, extends above this surface. Thus, interference with the tab occurs and eliminates radial rotation. The design flaw of this “welded” approach is the potential damage to the outer race due to heating generated in the welding process. Bearing manufacturers will not warranty this extreme modification of their design.
Another design flaw pertains to the motor shaft-to-bearing interface. Since the lead-end bearing must be “pre-installed” into the bearing cavity, the shaft bearing journal must therefore “slip-fit” into the bearing inner race. This method contradicts the bearing manufacturer's recommendations of “press-fitting” the bearings onto the rotating member of the machine. In other words, unless the bearing inner-race is pressed onto the shaft journal, “wallowing” or “slipping” of the shaft-bearing interface occurs. This results frequently in premature failures.
What is needed, then, is a device for overcoming these problems, and which particularly avoid problems associated with heat due to welding.
SUMMARY OF THE INVENTION
The present invention comprises an interference between a motor and a rotatable shaft. The interference includes a bracket, a bearing, and a bearing cap. The bracket is connected to the motor and defines a bearing bore. A bearing is positioned in the bearing bore and a bearing cap is connected to the bearing. Preferably, the bearing cap comprises a tang extending from a cover, wherein the bearing bore hub includes a boss positioned to prevent the tang from rotating.
The present invention also comprises a bearing anti-rotation apparatus and a bearing cap. It will be apparent to those skilled in the art that the present invention also comprises various methods of preventing wallowing and rotation of bearings.
Accordingly, an object of the present invention is to prohibit bearing outer race creepage.
Another object of the present invention is to eliminate potential damage due to welding.
Another object of the present invention is to reduce the “wallowing” or “slipping” in the shaft-bearing interface. This object is accomplished in one embodiment by pressing the bearing inner-race onto the shaft journal.
Another object of the present invention is to avoid premature failures.
Another object of the present invention is to assemble bearings in accordance with bearing manufacturers recommendations.
Another object of the present invention is to compensate for thermal expansion due to motor windings and bearing losses.
Other objects and advantages of the present invention will be apparent to those of skill in the art from the teachings disclosed herein.
REFERENCES:
patent: 2877068 (1959-03-01), Schaefer
patent: 3182379 (1965-05-01), Bachelet et al.
patent: 3655252 (1972-04-01), Crecelius
patent: 4384226 (1983-05-01), Sato et al.
patent: 4938452 (1990-07-01), Imamura et al.
patent: 5482384 (1996-01-01), Lyle
A.O. Smith Corporation
Hannon Thomas R.
Michael & Best & Friedrich LLP
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