Planetary gear transmission systems or components – Differential planetary gearing – Bevel gear differential
Reexamination Certificate
2000-02-07
2001-08-07
Estremsky, Sherry (Department: 3681)
Planetary gear transmission systems or components
Differential planetary gearing
Bevel gear differential
C475S198000
Reexamination Certificate
active
06270440
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a differential assembly for motor vehicles of the type used in motor vehicle drivetrain applications.
BACKGROUND OF THE INVENTION
Various types of differential assemblies are used in motor vehicles to redirect the transfer of power to the driving axles. In a rear-wheel drive vehicle, the transmission shaft from the gearbox turns the differential through a crown wheel and pinion. In a front-wheel drive car, the gearbox may drive the differential directly through a pair of helical spur gears. Four-wheel drive vehicles have two or three differentials, one for each driving pair of wheels and sometimes one between the front differential and the rear differential. All differentials allow the axle stub shafts or drive shafts, and subsequently, the wheels of the vehicle to be rotated at varying speeds as needed. In general, the side gears (which are connected to the axle stub shafts) and the pinion gears mesh to redirect the transfer of power to the driving axles/shafts.
In a typical differential gear arrangement, the drive pinion gear turns the differential input gear and the differential case attached to it. The differential pinion gears that are mounted in the case mesh with the differential side gears that are splined to the differential output shafts. In front-wheel drive vehicles, the drivetrain is often compacted into an engine/transaxle/driving axles “package” that provides torque to the front wheels. The transaxle assembly, comprising the transmission and the differential assembly, is often shipped modularly from vehicle powertrain plants to vehicle assembly plants to be installed in the vehicle. At the assembly plant, the axles are installed to the differential assembly by meshing them with the side gears. Once the axles have been installed, the transmission and differential assembly become enclosed and appropriate lubricating fluids are added to various components.
A disadvantage of conventional differential assemblies in front wheel drive transaxles is that they cannot be filled with lubricant until the drive shafts are installed at the assembly plant. Because the side gear and axle shafts are not assembled until they reach the assembly plant, the transaxle is not enclosed and is vulnerable to the ambient environment; therefore, special shipping and handling procedures are required to assure undamaged components. Moreover, valuable time and manpower are used at the final assembly plant for filling specific components with appropriate fluids following the installation of the axles into the differential assembly.
Additionally, the transaxle cannot be washed after filling since it is already assembled in the vehicle. Any spillage may be perceived as leakage by the customer. This causes unnecessary dissatisfaction and warranty cost. Also, filling in the vehicle is less accurate due to temperature variance and level inaccuracies.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide improved shipping and handling of a filled, sealed, and washed transaxle by keeping driveshaft driving and retaining features dry and internal to the modular assembly.
A further object of the invention is to reduce the time and manpower required at the assembly plant absorbed while adding appropriate fluids to drivetrain components.
An additional object of the invention is to increase the driveshaft lengths for reduced torque steer tendencies and improved constant velocity joint angles.
The present invention integrates the side gear with a hollow splined axle stub shaft which allows for easier assembly of the axle shaft at the assembly plant. In addition, the utilization of sealing devices (such as cup-shaped plug members) disposed within the hollow axle stub shafts to define an enclosed space to prevent fluid escape, thereby allowing a pre-filled and washed transmission to be shipped to the assembly plant.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 783168 (1905-02-01), Baker
patent: 2061009 (1936-11-01), Rothrock
patent: 3309943 (1967-03-01), Kosman et al.
patent: 59-205061 (1984-11-01), None
Adeyemi Nurudeen B
Bis Robert F
Mikel Steven A
Ward Jeffrey S
DaimlerChrysler Corporation
Estremsky Sherry
Lorelli Marc
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