Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2002-02-28
2003-09-09
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C324S627000, C074S443000
Reexamination Certificate
active
06616337
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OF DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
The present invention relates in general to noise reduction and more particularly to a machine component which reduces transmission of noise (vibrations) through it and to a bearing having the capacity to reduce noise.
Gear mechanisms and vehicular axle assemblies represent a major source of unwanted sound in industrial and automotive applications. In some industries, workers may suffer physical injury as a result of working near machinery which produces high levels of noise and vibration. In automotive applications, manufacturers are constantly looking for ways to reduce the interior sound level in the passenger compartments of their automobiles and trucks. In fact, low sound decibel readings in the interior of passenger cars have become important marketing issue for certain luxury automobiles.
In automotive gearboxes and axles, the attainment of lower audible noise levels can be limited by the inherent damping capacity of existing materials and components. For example, the advantage of using materials lighter than cast iron for transmission housings has not been fully exploited, because these lighter materials, such as aluminum and magnesium, have a lower damping capacity. Therefore, designers of these types of transmissions continue to look for ways of reducing the effect of gear noise that is transmitted along the shafts and through the bearings into the housings without compromising the stiffness of such systems.
A general review of the prior art in the field of noise reduction shows that virtually all the prior art depends upon the use of a resilient material to absorb vibration. This resilient material is usually positioned between the bearing and the bearing mounting device. But the resiliency of the materials detracts from the dimensional stability of the mountings. In the case of a transmission, this may result in less than optimum meshing of gears.
BRIEF SUMMARY OF THE INVENTION
The present invention resides in a machine component that contains a pocket bordered by reflecting surfaces which intersect at alternating peaks and valleys. Longitudinal noise waves propagating through the machine component, upon encountering the reflecting surfaces at the pocket, are partially converted into transverse waves, which are more easily attenuated in the material of the component. The machine component may take the form of a race for an antifriction bearing.
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Polster Lieder Woodruff & Lucchesi L.C.
The Timken Company
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