Machine element or mechanism – Elements – Gear casings
Reexamination Certificate
2001-12-14
2004-01-13
Hannon, Thomas R. (Department: 3682)
Machine element or mechanism
Elements
Gear casings
C277S637000
Reexamination Certificate
active
06675676
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a cover for a differential unit of a vehicle, and more particularly, the present invention relates to a cover for a differential unit that is shaped to optimize sealing between the differential cover and the differential housing.
BACKGROUND OF THE INVENTION
Presently, vehicles are equipped with a differential gearing unit positioned between the vehicle transmission and output axles to supply a driving force to the vehicle wheels. The differential unit, itself, contains gearing to adjust the torque and velocity relationship from that supplied from the transmission output shaft (and into the differential) and the resultant torque and rotational velocity supplied to the output axles. The differential further includes a differential housing and differential cover which assemble to protect the gearing from the external environment and to maintain lubricants within the housing. Accordingly, the sealing relationship between the differential cover and the housing is of critical importance to ensure that lubricants do not leak out and external contaminants, such as dirt, do not enter the working environment of the differential gearing. To effectuate this assembly, a plurality of bolts provide a clamping force to clamp a gasket between the cover and the housing. The bolts connect the cover and the housing and apply a pressing force on the gasket to maximize sealing. While this arrangement does provide sealing capabilities, some drawbacks exist. Specifically, the clamping force applied to the gasket in the immediate proximity of the bolts is greater than the clamping force provided along the cover at positions between the bolts. As such, these areas have a lower clamping force and lower contact sealing stress/pressure distribution, and are therefore more susceptible to leakage than that of areas proximate the bolts. The present invention was developed in light of these and other drawbacks.
SUMMARY OF THE INVENTION
To address these and other drawbacks, a differential cover for a differential unit of a vehicle includes a central area, a flange area having a lower surface facing a mating direction for mating with a surface of a differential housing. The flange area has a plurality of apertures distributed along the flange area. The flange between centerlines of adjacent apertures defines a plurality of segments, each of which extends further in the mating direction than the lower surfaces of the segment at respective centerlines.
In another aspect, a differential unit for a vehicle includes a housing, a differential cover having a flange, and a gasket positioned between the flange and the housing to seal an interior of the housing from an external environment. The differential cover is attached to the housing by a plurality of bolts which pass through the flange and clamp the differential cover to the gasket to apply a clamping force to the gasket. The flange is elastically deformed at areas between the bolts to provide a clamping force to the gasket. As a result, a combined force on the gasket caused by the elastically deformed areas and the bolts provide a substantially equal clamping force which translates to substantially equal contact sealing pressure distribution on the gasket.
Further areas of applicability of the present invention will become apparent from the entailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
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Americam Axle & Manufacturing, Inc.
Hannon Thomas R.
Harness & Dickey & Pierce P.L.C.
Johnson Vicky A.
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