Planetary gear transmission systems or components – Input from independent power sources – Plural outputs
Reexamination Certificate
1999-09-03
2001-03-27
Wright, Dirk (Department: 3681)
Planetary gear transmission systems or components
Input from independent power sources
Plural outputs
C475S028000
Reexamination Certificate
active
06206798
ABSTRACT:
BACKGROUND OF THE INVENTION
The subject invention relates to a differential apparatus including an auxiliary input mechanism to control the wheel speed of a vehicle.
Conventional differential apparatuses for controlling the wheel speed of a vehicle are known in the art. Generally, a differential apparatus transmits a driving force from a vehicle engine to an output shaft or shafts of the vehicle. Ultimately this driving force is transmitted to the vehicle wheels, which are associated with the output shafts of the vehicle. The operating performance of the vehicle wheels is dependant on the amount of torque available at the wheels. Conventional differentials typically include an exclusive input for controlling the wheel speed of the vehicle. That is, the driving force from the vehicle engine is typically transmitted by a single pinion gear that is mounted to a drive shaft of the vehicle. The pinion gear operates as the exclusive input to the conventional differential apparatus.
As a result of this exclusive input, when such conventional differentials are applied particularly to a heavy vehicle having wheels or to a track-driven vehicle the amount of torque available at the wheels is affected. More specifically, if a wheel on a first side of the differential slips due to poor traction conditions, the torque available at a wheel on the other side of the differential can be no more than the torque that is developed at the wheel on the first side that is slipping due to the poor traction conditions. This is true regardless of the traction conditions at the wheel on the other side of the differential. That is, the torque that is developed at the wheel on the other side of the differential can be no more than the torque that is developed at the wheel on the first side even if satisfactory traction conditions are present at the wheel on the other side of the differential.
Furthermore, such conventional differential apparatuses limit the effectiveness of the vehicle because the output shafts are restricted to rotation in the same direction. As a result, it is not possible for the vehicle to pivot about a stationary position. That is, the vehicle cannot turn without progressing forward or backward to some degree. Pivoting about a stationary position is a critical and therefore desirable characteristic in the heavy vehicle or track-driven vehicle industries where these vehicles are frequently required to function in confined spaces.
All of these problems became particularly acute in differentials that utilize planetary transmissions.
Due to the inefficiencies identified in conventional differential apparatuses, it is desirable to implement a differential apparatus that incorporates an auxiliary input mechanism that enables different rotational speeds and different rotational directions of the output shafts of a vehicle to more effectively control the wheel speed and traction of a vehicle.
SUMMARY OF THE INVENTION AND ADVANTAGES
A differential apparatus for controlling the wheel speed of a vehicle comprises a primary driving input, and first and second output shafts. A first planetary gear system is in driving engagement for rotating the first output shaft. Similarly, a second planetary gear system is in driving engagement for rotating the second output shaft. Further, the first planetary gear system includes a first ring gear, and the second planetary gear system includes a second ring gear. The apparatus also includes at least one auxiliary input mechanism in selective driving engagement with the first and second planetary gear systems for rotating the first and second ring gears in opposite directions to effect different rotational speeds to the first and second output shafts.
By selectively driving the ring gears of each planetary gear system in opposite directions, the auxiliary input mechanism ultimately effects different rotational speeds to the vehicle wheels. As a result, various operational capabilities of the vehicle, including steering and traction capabilities, are not diminished but are enhanced during turning of the vehicle. Further, by selectively driving the ring gears of the planetary gear systems in opposite directions, the rotational direction of one output shaft may be different from the rotational direction of the other output shaft, and it is possible for the vehicle to pivot about a stationary position without the vehicle progressing forward or backward—a characteristic that is desirable when operating the vehicle such as a fork lift, in confined spaces.
Accordingly, the subject invention provides a differential apparatus that incorporates an auxiliary input mechanism that enables different rotational speeds and different rotational directions of the output shafts of a vehicle to more effectively control the wheel speed of a vehicle and to provide maximum torque to each wheel regardless of traction conditions. Consequently, the differential apparatus of the subject invention enhances the operational capabilities of the vehicle, including steering and tractional capabilities.
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patent: 3530741 (1970-09-01), Charest
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patent: 4776235 (1988-10-01), Gleasman et al.
patent: 4848186 (1989-07-01), Dorgan et al.
patent: 5168946 (1992-12-01), Dorgan
patent: 5415595 (1995-05-01), Nelson
patent: 5685798 (1997-11-01), Lutz et al.
Carlson & Gaskey & Olds
Meritor Heavy Vehicle Systems LLC
Wright Dirk
LandOfFree
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