Planetary gear transmission systems or components – Differential planetary gearing – Bevel gear differential
Reexamination Certificate
2001-04-17
2003-04-08
Lorence, Richard M. (Department: 3681)
Planetary gear transmission systems or components
Differential planetary gearing
Bevel gear differential
C384S585000
Reexamination Certificate
active
06544140
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates in general to a tapered roller bearing design and arrangement and, more particularly, to a direct tapered roller bearing arrangement for mounting a pinion gear into a differential gear mechanism wherein the design and installation method of the tapered roller bearings provide a number of significant advantages over indirect tapered bearing mounting arrangements.
2. Description of Related Art
Differential gear mechanisms transfer rotational torque from an input shaft member to a pair of output shaft members. The input member is usually driven by a torque generating device such as a gasoline engine or an electric motor. Normally, the torque from the torque generating device is transferred to the input shaft member of a differential gear mechanism by a yoke which is splined to engage with one end of the input shaft member.
In conventional differential gear assemblies the output shaft members are generally located perpendicular to the input shaft member. Most differential gear mechanisms use a drive pinion gear which mates with an adjoining ring gear to transfer the torque from the input shaft member to the output shaft members. Anti-friction bearings are incorporated into the differential gear assembly to allow all shaft members to rotate in a generally free manner.
The design and bearing arrangement of previous differential gear mechanism designs offer a wide variety of pinion gear bearing arrangements. U.S. Pat. No. 6,056,663 to Fett is one example of the current state of the commonly accepted arrangement of pinion bearings. There, the pinion gear uses two tapered roller bearings to support the shaft of the pinion gear. However, the mounting style for the bearings makes it very difficult to replace these bearings. The differential gear mechanism must be substantially disassembled to replace the bearings. Additionally, the pinion gear on the pinion shaft is unsupported by any bearing which leaves the pinion gear unsupported in the mechanism allowing heavy cantilever loads to be placed upon the pinion shaft bearings.
U.S. Pat. No. 5,098,355 to Long describes a differential gear mechanism which uses tapered roller bearings on the pinion shaft mounted in a manner which allows for a somewhat easier replacement of the pinion shaft bearings. However, the bearings are arranged in an indirect mounting style which fails to provide the stiffest support for the pinion shaft. While the pinion gear end of the pinion shaft is supported by a bearing, the bearing is not a tapered roller bearing and thus fails to offer adequate protection against the axial and thrust loads found in differential gear mechanisms. It is also clear that the bearing used to support the pinion gear end of the pinion shaft is not designed for easy replacement and will require substantial disassembly of the differential gear mechanism to replace the bearing.
In each of these examples, several bearings are used to support the pinion shaft gear. The large number of bearings used and the difficulty of replacing these bearings, makes these differential gear mechanisms costly to manufacture and to maintain. The type of bearings used and the arrangement of those bearings also fails to provide the best support for the pinion shaft to compensate for all of the radial and thrust loads which occur in differential gear mechanisms.
SUMMARY OF THE INVENTION
The present invention resides in a pinion mounting with a direct tapered roller bearing arrangement for use in differential gear mechanisms. Specifically, two tapered roller bearings are mounted in a direct arrangement, with tapered roller bearings uniquely designed for quick replacement and setting capabilities. One tapered roller bearing supports a pinion gear shaft at an intermediate point on the shaft. The bearing is designed for either flange mounting or threaded mounting of the tapered roller bearing to the exterior of the casing for a differential gear mechanism. The second tapered roller bearing supports the pinion gear end of the pinion gear shaft. Shims are used to dimensionally set the bearings to allow for proper bearing preload, and for proper engagement of the pinion gear and the ring gear of the differential gear mechanism.
The design of the present invention thus provides for a pinion mounting removable from the differential gear mechanism casing without disassembly of other components of the differential gear mechanism. The present invention also provides a simplified pinion assembly when compared to devices using indirect tapered roller bearing mounting. Bearing setting is also simpler in the present invention than in the standard tapered roller bearing arrangement, which also makes the present invention suitable for dimensional setting. Additionally, the current invention offers a more compact arrangement than an indirect tapered roller bearing or straddle mounting arrangement because of the shorter pinion stem and housing of the present invention. The seal is integrated into the exterior bearing of the present invention, thus creating a better sealing of the differential gear mechanism. Because load distribution is an important factor in differential gear mechanisms, it is important to note that the present invention also provides a better load distribution when compared to conventional straddle mounted bearings. This also translates to a potential for better stiffness within the present invention when compared to indirect mounted tapered roller bearings. Finally, as a result of the potential for bearing downsizing within the current inventions as compared to the conventional tapered roller bearing arrangement, the present invention also offers the significant potential for better efficiency in design when compared to straddle mounted bearings.
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Gradu Mircea
Hill Harold E.
Abdelnour Dennis
Lorence Richard M.
Polster Lieder Woodruff & Lucchesi L.C.
The Timken Company
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