Modular unitized differential

Details Modular unitized differential Modular unitized differential

1999-12-16

2001-03-06

Wright, Dirk (Department: 3681)

Planetary gear transmission systems or components

Differential planetary gearing

Bevel gear differential

C074S60600R

Reexamination Certificate

active

06196942

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to differential transmission mechanisms, particularly a differential utilized in an automotive axle drive.
2. Description of the Prior Art
A differential gear in a final drive axle of a motor vehicle transmits a rotational input from an engine to two axle shafts. A differential case is rotatably supported on an axle housing. Typically, a differential case comprises two halves: a plain differential case half and a flanged differential case half, usually bolted to each other. The flanged differential case half is provided with a flange that receives a ring gear attached to the flange by a number of bolts. In order to provide the adequate stiffness of the differential gear, the flanged differential case half is conventionally provided with a plurality of stiffening ribs.
The ring gear is engaged with a pinion gear of a final drive. In such a case, to account for assembly tolerances, shim packs may be disposed between the ring gear and the flange of the differential case to properly align the ring gear with the pinion gear. Such prior art assemblies are costly and cumbersome.
Furthermore, presently, each model of automobile (both cars and trucks) may have variants having different final drive gear ratios for various specific applications. The different final drive gear ratios require different gear teeth combinations, thus automobile manufacturers need to provide differentials with different gear spacings (or offsets). For instance, heavy duty truck drive axle differential manufacturers have to use up to four different flanged differential case halves to cover the offsets of all gear ratios employed.
SUMMARY OF THE INVENTION
The present invention alleviates the drawbacks of the prior art. The present invention provides selective axial positioning of the ring gear relative to the differential case for welding in a specific position to accommodate different gear ratios between the ring gear and an input gear. The present invention also eliminates bolts or other complicated fastening devices to secure the ring gear to the differential case. Manufacture and assembly tolerances may also be accounted for.
The modular unitized differential in accordance with the present invention comprises a flanged differential case and a bowl-shaped ring gear having a concave flange portion. The concave flange portion of the ring gear greatly improves the stiffness and impact resistance of the differential, thus eliminating the need for the stiffening ribs. During the manufacturing of the differential, the ring gear is mounted on the differential case, selectively positioned in a specific axial position by sliding the ring gear relative to the differential case, and welded in place. This arrangement enables to accommodate different gear ratios between the ring gear and input gear.


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