Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
1998-12-16
2001-01-09
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S572000, C384S450000
Reexamination Certificate
active
06170993
ABSTRACT:
TECHNICAL FIELD
This invention relates to ball bearings and more particularly to separators for randomly spacing the balls in the bearing to reduce lobing effects.
BACKGROUND OF THE INVENTION
Ball bearings are used to support the wheels of vehicles. The ball bearings have an inner race, an outer race and a plurality of balls housed in a separator or cage between the races. Ball race surfaces are machined in the inner and outer races. These surfaces are ground to provide close tolerances of size, surface finish and roundness. This will produce a smooth rolling surface for the balls. The grinding process can produce evenly spaced lobes, on either the inner or outer race, of very small amplitude and continue to be acceptable within the roundness tolerances. This lobing effect induces an impulse each time a ball passes over one of the lobes. This impulse can be significant when a number of lobes are simultaneously aligned with respective ones of the balls. Since the balls are evenly spaced in a separator, the impulse created thereby will be very significant if the number of lobes is a whole number multiple of the number of balls in the bearing.
The frequency of the impulses varies with the rotary speed of the wheel being supported. If the frequency of the impulses approaches the resonant frequency of the suspension system supporting the vehicle on the wheel, the induced vibration will become very noticeable in the form of noise and vibration. With the current technology in suspension design, the elements of the suspension tend to be lighter and stiffer.
One solution that has been proposed and is in use is the imposition of tighter tolerance limits on the roundness specification of the races. This tolerance tightening results in the need for one-hundred percent (100%) inspection on a tracing apparatus. This is an expensive procedure and is not practical in a high volume manufacturing environment. In lieu of this procedure, periodic inspections are performed to insure the process is under control. However, this can miss some bearing races with excess lobing.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved ball bearing having reduced lobing effect.
In one aspect of the present invention, the balls are randomly spaced around the circumferences of the races. In another aspect of the present invention, the pockets of the separator are not evenly spaced. In yet another aspect of the present invention, design criteria such as nominal chordal distance, pitch circle diameter of the balls, number of balls in the complement and the diameter of the separator pocket are evaluated to determine the ball spacing.
In a further aspect of the present invention, a minimum distance between adjacent balls is established to permit a structurally sound separator. In a yet further aspect of the present invention, the chordal distance which is greater than the minimum distance between adjacent ball pockets is determined by using randomizing techniques. In a still further aspect of the present invention, the minimum distance is added to each calculated random distance to determine the desired chordal distance between adjacent pockets.
REFERENCES:
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patent: 3882583 (1975-05-01), Thacker et al.
patent: 3918778 (1975-11-01), Jacobson et al.
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patent: 4523666 (1985-06-01), Murray
patent: 4567975 (1986-02-01), Roll
patent: 5004359 (1991-04-01), Jacobson
patent: 5022267 (1991-06-01), Shattuck et al.
patent: 5678310 (1997-10-01), Chiba
patent: 5927858 (1999-07-01), Agari
Brough Raymond Beryl
Hurrell, II George Leonard
Meeker Steven Eugene
General Motors Corporation
Hannon Thomas R.
Hansen Colby
McBain Scott A.
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