Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Control of differential planetary gearing
Reexamination Certificate
2003-02-05
2004-11-16
Bonck, Rodney H. (Department: 3681)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Control of differential planetary gearing
C475S231000, C475S150000
Reexamination Certificate
active
06817961
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to differentials for motor vehicles and, more particularly, to a limited slip differential employing a magneto-rheological fluid to control operation of the differential.
As is known, many motor vehicles are equipped with driveline systems including differentials which function to drivingly interconnect an input shaft and a pair of output shafts. The differential functions to transmit drive torque to the output shafts while permitting speed differentiation between the output shafts.
Conventional differentials, such as a parallel-axis helical differential, include a pair of side gears fixed for rotation with the output shafts and two or more sets of meshed pinion gears mounted within a differential case. However, the conventional differential mechanism has a deficiency when a vehicle is operated on a slippery surface. When one wheel of the vehicle is on a surface having a low coefficient of friction, most or all of the torque will be delivered to the slipping wheel. As a result, the vehicle often becomes immobilized. To overcome this problem, it is known to provide a mechanical differential where an additional mechanism limits or selectively prevents differentiation of the speed between the output shafts. Typically, the mechanical device to provide the limited-slip or non-slip function is a friction clutch. The friction clutch is a passive device which limits the differential speed between the output shafts only after a certain differential speed has been met. Additionally, such mechanical devices may not be selectively disengaged during operation of anti-lock braking systems or vehicle traction control systems. For example, four wheel anti-lock braking systems attempt to measure and control the rotational speed of each wheel independently. If a mechanical type limited slip differential is present, independent control of the speed of each wheel coupled to a differential is no longer possible. Accordingly, it would be desirable to provide an improved differential which may be actively controlled in conjunction with other control systems present on the vehicle.
SUMMARY OF THE INVENTION
The present invention relates to a differential system including a case, a pair of pinion gears, a pair of side gears and an electrically operable coupling including a magnetically responsive fluid. The coupling selectively drivingly interconnects one of the side gears and the case. In one instance, the present invention includes a rotor having a plurality of outwardly extending blades positioned in communication with a magneto-rheological fluid. An electromagnet is selectively actuated to change the viscosity of the magneto-rheological fluid. In this manner, the differential may function as an “open” differential, a “locked” differential or a differential accommodating a limited slip condition.
Another aspect of the present invention includes a differential system having an electronic controller wired in communication with the magneto-rheological coupling. The electronic controller is supplied with data from many vehicle sensors and systems such as an anti-lock braking system, a vehicle traction control system, or a cruise control system. The electronic controller may be programmed to actuate the magneto-rheological coupling based on calculations performed by the electronic controller or any number of inputs such as those received from vehicle sensors such as those detecting wheel speed, gear position, vehicle speed, transfer case range position, application of one or more brakes, among others.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
REFERENCES:
patent: 4444298 (1984-04-01), Stangroom
patent: 4896754 (1990-01-01), Carlson et al.
patent: 5007513 (1991-04-01), Carlson
patent: 5147252 (1992-09-01), Mace et al.
patent: 5158507 (1992-10-01), Guimbretiere
patent: 5322484 (1994-06-01), Reuter
patent: 5358084 (1994-10-01), Schramm
patent: 5730531 (1998-03-01), Pinkos et al.
patent: 5779013 (1998-07-01), Bansbach
patent: 5845753 (1998-12-01), Bansbach
patent: 5915513 (1999-06-01), Isley, Jr. et al.
patent: 6183386 (2001-02-01), Duggan
patent: 6334832 (2002-01-01), Heravi et al.
patent: 6428441 (2002-08-01), Hunt
patent: 6454674 (2002-09-01), Krzesicki et al.
patent: 6527661 (2003-03-01), Leeper
patent: 6585616 (2003-07-01), Robinson
Moore Jason E.
Zink Frederick E.
Abdelnour Dennis J.
American Axle & Manufacturing Inc.
Bonck Rodney H.
Harness & Dickey & Pierce P.L.C.
LandOfFree
Magnetically responsive limited slip differential does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetically responsive limited slip differential, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetically responsive limited slip differential will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3314694