Planetary gear transmission systems or components – Variable speed or direction transmission combined with... – Variable speed or direction is planetary transmission
Reexamination Certificate
2001-10-24
2003-09-23
Parekh, Ankur (Department: 3681)
Planetary gear transmission systems or components
Variable speed or direction transmission combined with...
Variable speed or direction is planetary transmission
C180S248000, C192S056600, C464S046000
Reexamination Certificate
active
06623395
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to a torque limiting sprocket assembly and more particularly to a chain sprocket assembly having an integral torque limiting clutch. The assembly may be advantageously, though not exclusively, used in motor vehicle transfer cases and other vehicle power train components.
The delivery of power and specifically drive torque in a four-wheel drive motor vehicle from a primary drive line which is continuously active to a secondary drive line which may deliver torque to a secondary set of drive wheels on a part time basis is the subject of much study and innumerable mechanical configurations and operating routines. Broadly speaking, an energy transfer device operably resides between the primary and secondary drive lines in a transfer case and delivers torque from the primary drive line to the secondary drive line. The energy transfer device may take many forms: an inter-axle differential, a two state device such as a dog clutch having only engaged and released operating states, an overrunning clutch which engages only when a speed difference exists between the drive lines, a viscous clutch which provides increasing resistance and torque transfer with increasing speed difference between the drive lines and an electrically or hydraulically modulatable friction clutch which may be controlled according to diverse programs and operating sequences to apportion torque delivery to the drive lines from 100% to the primary drive line (0% to the secondary drive line) to a 50%—50% torque split between the drive lines and typically at many or an infinite number of levels therebetween.
Particularly in the two stage (on-off) and inter-axle differential systems but in the overrunning, viscous and modulatable systems as well, it may be beneficial to limit the maximum torque delivered to the secondary drive line wheels. For example, a particular vehicle weight, weight distribution or intended service environment may dictate limiting the torque delivered to the secondary (typically front) axle and wheels of a four wheel drive vehicle in order to provide optimum performance. Similarly, it may be desirable from an overall vehicle operation standpoint to limit the maximum torque delivered to the secondary axle and wheels.
The present invention relates to a torque limiting assembly which may be disposed integrally with one the chain sprockets in a chain drive assembly of a typical transfer case.
BRIEF SUMMARY OF THE INVENTION
A chain sprocket assembly for use in a motor vehicle transfer case having an inter-axle differential includes a torque limiting clutch which limits the torque provided to a secondary drive line. The chain sprocket assembly includes a chain receiving hub having a splined interconnection which drives an outer bell housing having internal splines which drive a first set of friction clutch plates. A second set of friction clutch plates are interleaved with the first set of clutch plates and are splined to and drive a stub shaft. The stub shaft also freely rotatably receives the chain hub and functions as the secondary output to drive a secondary drive line. A biasing spring engages the clutch plates and compresses them and achieves a desired maximum torque throughput from the chain to the secondary output shaft. In operation, the chain sprocket assembly will transmit torque to the secondary output shaft and the secondary drive line up to the preselected maximum at which threshold the friction clutch pack will slip, thus limiting torque throughput to the preselected level. Two alternate embodiments of the torque limiting chain drive sprocket assembly are also disclosed.
Thus, it is an object of the present invention to provide a chain sprocket having an integral torque limiting clutch.
It is a further object of the present invention to provide a chain sprocket having an integral torque limiting clutch which may be disposed in a transfer case or other motor vehicle power train component.
It is a still further object of the present invention to provide a torque limiting clutch assembly which may be disposed within a chain sprocket in the chain drive assembly of a motor vehicle transfer case or similar vehicle power train component.
Further objects and advantages of the present invention will become apparent by reference to the following description of the preferred and alternate embodiments and appended drawings wherein like reference numbers refer to the same component, element or feature.
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Borg-Warner Inc.
Brinks Hofer Gilson & Lione
Parekh Ankur
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