Bi-directional overrunning clutch

Abstract

A bi-directional overrunning clutch is disclosed for controlling torque transmission between a secondary drive shaft and secondary driven shafts. The overrunning clutch includes a pinion input shaft in a differential housing that engages with a clutch housing rotatably disposed within the differential housing. At least one race is located adjacent to the clutch housing and is engaged with an output shaft. A cage is located between the race and the clutch housing. The cage is movable with respect to the clutch housing. A <DEL-S DATE="20030304" ID="DEL-S-00001" / >first<DEL-E ID="DEL-S-00001" / > coil is mounted within the differential housing adjacent to the cage and is adapted to produce an electromagnetic field when energized which causes the cage to drag with respect to the clutch housing. The dragging of the cage with respect to the clutch housing positions <INS-S DATE="20030304" ID="INS-S-00001" / >rolls within <INS-E ID="INS-S-00001" / >the cage to engage the clutch housing with the race when wheels on a primary drive shaft lose traction. <DEL-S DATE="20030304" ID="DEL-S-00002" / >A<DEL-E ID="DEL-S-00002" / > <INS-S DATE="20030304" ID="INS-S-00002" / >If desired a <INS-E ID="INS-S-00002" / >second coil <DEL-S DATE="20030304" ID="DEL-S-00003" / >is<DEL-E ID="DEL-S-00003" / > <INS-S DATE="20030304" ID="INS-S-00003" / >may be <INS-E ID="INS-S-00003" / >mounted within the differential housing adjacent <DEL-S DATE="20030304" ID="DEL-S-00004" / >adjacent<DEL-E ID="DEL-S-00004" / > to the cage. The second coil is adapted to produce an electromagnetic field when energized which advances cage with respect to the clutch housing causing the clutch housing to engage with the races. When the second coil is activated, the output shaft drives the pinion input shaft producing engine braking. An electronic control system is utilized to control the energizing of the coils.

Description

FIELD OF THE INVENTIONThe present invention relates to clutches and, more particularly, to a bi-directional electromechanical overrunning clutch for providing four wheel drive capability.BACKGROUND OF THE INVENTIONThe increased demand in recent years for off-road and all terrain vehicles has led to tremendous developments in those types of vehicles. Many of the developments have centered around making the vehicle more adaptable to changing road conditions, e.g., dirt roads, pavement and gravel. As the road terrain changes, it is desirable to vary the driving capabilities of the vehicle to more efficiently navigate the new terrain. Prior four-wheel drive and all terrain vehicles were cumbersome since they required the operator to manually engage and disengage the secondary drive shaft, e.g., by stopping the vehicle to physically lock / unlock the wheel hubs. Improvements in vehicle drive trains, such as the development of automated systems for engaging and disengaging a driven axle, el...

AI Technical Summary

Benefits of technology

.[.A.]. .Iadd.In one embodiment, a .Iaddend.second armature plate is located adjacent the roll cage. A second coil is mounted within the differential housing adjacent to the second armature plate. The second coil is adapted to produce an electromagnetic field when energized to hinder the rotation of the second armature plate. This causes the roll cage to advance with respect to the clutch housing causing the clutch housing to engage with the races. In this mode of operation, the secondary driven half shafts and output shaft drive the pinion input shaft and secondary drive shaft, thereby producing engine braking.

In another embodiment, a third armature plate is located adjacent to the roll cage and a third coil is mounted within the differential housing adjacent to the third armature plate. The third coil produces an electromagnetic field when energized which hinders the rotation of the third armature plate. This causes the roll cage to move opposite the direction of rotation of the clutch housing to assist in disengaging the rolls from between the clutch housing and the races.

The clutch housing preferably has a plurality of toggle levers pivotally attached thereto that engage with pins mounted on the roll cage. The engagement between the toggle levers and the pins permits the roll cage to be advanced and retarded with respect to the clutch housing. The second armature plate engages with the toggle lever to advance the cage and the third armature plate engages with the toggle lever to retard the cage.

Problems solved by technology

Prior four-wheel drive and all terrain vehicles were cumbersome since they required the operator to manually engage and disengage the secondary drive shaft, e.g., by stopping the vehicle to physically lock / unlock the wheel hubs.

An open differential allows differential action between the half shafts but, when one wheel loses traction, all available torque is transferred to the wheel without traction resulting in the vehicle stopping.

Some of the more expensive limited slip differentials use sensors and hydraulic pressure to actuate the clutch packs locking the two half shafts together.

The benefits of these hydraulic (or viscous) units are often overshadowed by their cost, since they require expensive fluids and complex pumping systems.

The heat generated in these systems, especially when used for prolonged periods of time may also require the addition of an auxiliary fluid cooling source.

The primary drawback to these types of differentials is that the two half shafts are no longer independent of each other.

This can result in problems during turning where the outside wheel tries to rotate faster than the inside wheel.

Another problem that occurs in locking differentials is twichiness when cornering due to the inability of the two shafts to turn at different speeds.

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