Abstract: A transfer case for a four-wheel drive vehicle includes a center differential which provides a direct output in two-wheel drive and a slightly reduced speed output in four-wheel drive. In two-wheel drive, the outputs of the center differential are locked together by a clutch collar and drive torque is provided to the primary drive line only. In four-wheel drive, the clutch collar unlocks the differential and couples the output from a sun gear to a chain drive sprocket in the secondary drive line. The center differential is driven through the carrier and operates as an open differential. The ring (outer) gear drives the primary drive line and the sun (center) gear drives the secondary drive line through cooperating chain sprockets and a chain. The chain drive sprockets are of unequal size and effect a speed reduction between the drive and driven sprockets. This speed reduction is nominally the same as the speed reduction from the input to the primary output achieved through the center differential.

Abstract: An adaptive torque control and distribution system for a motor vehicle having a transfer case, primary driveline and drive wheels and secondary driveline and drive wheels for operation in extreme off road conditions such as sand. The transfer case includes a modulating clutch and a lockup clutch disposed in parallel between its primary (rear) output and secondary (front) output. The system detects abnormally high magnitude and rapidly repeating wheel spin transients which are characteristic of operation in sand or similar highly randomly variable tractive conditions and overrides the on demand torque distribution program for a predetermined time interval. During this predetermined time interval, the transfer case lockup clutch is activated thereby coupling the primary and secondary drivelines and achieving a fifty-fifty torque split therebetween while the modulating clutch is inactive.

Abstract: A modulating clutch for disposition and use in a motor vehicle drive train includes a disc pack clutch assembly and clutch actuator. The clutch actuator includes an assembly for generating compressive force which is applied to the clutch pack assembly and a preload member which partially engages the clutch pack to provide torque transfer up to a predetermined level without activation of the clutch actuator. Activation of the clutch actuator increases the torque transfer or throughput above the predetermined level. The differential of the present invention thus functions passively as a limited slip differential by allowing torques in excess of the predetermined torque level to slip each axle relative to the driveline input thereby provide a constant, minimum level torque coupling between the driveline and each axle. When the clutch actuator is energized, it may be utilized to control torque transfer at levels above the predetermined level between the input and output of the clutch mechanism.

Abstract: A clutch assembly for disposition in a motor vehicle drive line includes an internal reaction force circuit. The clutch assembly includes a multiple disc friction clutch disposed adjacent an operator assembly which selectively applies force to the friction clutch to selectively transfer torque therethrough. The clutch components are disposed between fixed stops on an elongate member which functions as a reaction force member to self-contain the reaction force from the clutch operator. The clutch finds application in motor vehicle drive line components such as a rear (secondary) axle in which it is disposed in pairs to independently control torque supplied to each axle and in applications where it is advantageous to contain or ground the reaction force generated by and associated with the clutch operator compactly within the clutch structure rather than its housing.

Abstract: A transfer case having a two-speed drive assembly includes a directly coupled shift operator with feedback. The shift operator includes an electric, pneumatic or hydraulic motor which directly, rotatably drives a shift rail. The shift rail includes threads and receives a shift fork having complementary threads. The shift fork engages a dog clutch. Bi-directional rotation of the shift rail correspondingly bi-directionally translates the shift fork to select direct drive (high gear), reduced speed drive (low gear) or neutral operation of the two-speed drive assembly. A shift rail position sensor provides data to associated logic and command circuitry regarding the actual position of the shift fork.

Abstract: An axle differential for the secondary driveline of a four-wheel drive vehicle includes individual modulatable axle clutches that may be commonly or individually activated to control torque delivery to the secondary drive wheels. The differential includes an input shaft driving a bevel gear set, the modulatable clutches and left and right output shafts. Each of the modulatable clutches include a disc pack clutch assembly having first and second interleaved pluralities of clutch plates, a ball ramp operator and an electromagnetic coil which acts upon the ball ramp operator which applies compressive force to the interleaved clutch plates. An operating program for controlling left-right secondary wheel slip may be utilized with the differential.

Abstract: A two speed planetary gear assembly and double disconnect mechanism for a motor vehicle transfer case or similar device achieves full decoupling of the speed reduction assembly from the power path when either neutral or the high speed gear ratio, typically direct drive, is selected. The double disconnect mechanism includes an axially slidable clutch collar freely rotatably disposed within a correspondingly movable reduction hub which may selectively be translated to engage either a direct drive member or an input to a planetary gear assembly. When the reduction hub is positioned to engage the input of the planetary gear assembly, a gear set on the carrier of the planetary gear assembly engages the reduction hub which drives it and the output member at reduced speed.

Abstract: A method and apparatus for operating a power transfer device such as a vehicle transfer case having, shaft speed sensors, a two speed (high-low) drive assembly, an electrically, pneumatically or hydraulically operated shift operator and a microprocessor comprising the steps of sensing the speeds of the transfer case input shaft and output shaft, calculating the rate of change (.DELTA.S/.DELTA.t) of the speed of the input shaft, predicting, based upon such rate of change, a time when the input shaft and the output shaft will be synchronized and commencing movement of such shift operator at a time prior to such synchronization in order to effect engagement of such clutch into high gear at substantially the instant of synchronization.

Abstract: A differential assembly for a transfer case or other motor vehicle application comprehends a pair of side gears which flank a centrally disposed spider driven by an input member and having a plurality of spokes or shafts and bevel pinion gears disposed thereon. An annular member retains the bevel gears on the spider. In a first embodiment, the annular member is retained on the spider by cooperating elongate slots in the member which receive the shafts of the spider and a snap ring which extends about the circumference of the annular member. In an alternate embodiment, the pinion gears include projecting spherical surfaces which are complementary to and seat within spherical recesses on the inner surface of the annular member.

Abstract: An adaptive torque control and distribution system for a motor vehicle having a transfer case, primary driveline and drive wheels and secondary driveline and drive wheels for operation in extreme off road conditions such as sand. The transfer case includes a modulating clutch and a lockup clutch disposed in parallel between its primary (rear) output and secondary (front) output. The system detects abnormally high magnitude and rapidly repeating wheel spin transients which are characteristic of operation in sand or similar highly randomly variable tractive conditions and overrides the on demand torque distribution program for a predetermined time interval. During this predetermined time interval, the transfer case lockup clutch is activated thereby coupling the primary and secondary drivelines and achieving a fifty-fifty torque split therebetween while the modulating clutch is inactive.

Abstract: A modulating clutch for disposition and use in a motor vehicle drive train includes a disc pack clutch assembly and clutch actuator. The clutch actuator includes an assembly for generating compressive force which is applied to the clutch pack assembly and a preload member which partially engages the clutch pack to provide torque transfer up to a predetermined level without activation of the clutch actuator. Activation of the clutch actuator increases the torque transfer or throughput above the predetermined level. The differential of the present invention thus functions passively as a limited slip differential by allowing torques in excess of the predetermined torque level to slip each axle relative to the driveline input thereby provide a constant, minimum level torque coupling between the driveline and each axle. When the clutch actuator is energized, it may be utilized to control torque transfer at levels above the predetermined level between the input and output of the clutch mechanism.

Abstract: An axle differential for the secondary driveline of a four-wheel drive vehicle includes individual modulatable axle clutches that may be commonly or individually activated to control torque delivery to the secondary drive wheels. The differential includes an input shaft driving a bevel gear set, the modulatable clutches and left and right output shafts. Each of the modulatable clutches include a disc pack clutch assembly having first and second interleaved pluralities of clutch plates, a ball ramp operator and an electromagnetic coil Which acts upon the ball ramp operator which applies compressive force to the interleaved clutch plates. An operating program for controlling left-right secondary wheel slip may be utilized with the differential.

Abstract: An on demand vehicle drive system monitors vehicle performance and operating conditions and controls torque delivery to the vehicle wheels. The system includes a plurality of speed and position sensors, a transfer case having primary and secondary output shafts driving primary and secondary axles and a microcontroller. The sensors include a vehicle speed sensor, a pair of primary and secondary drive shaft speed sensors, and brake and driveline status sensors. The transfer case includes a modulating electromagnetic clutch controlled by the microcontroller which is incrementally engaged to transfer torque from the primary output shaft to the secondary output shaft. When the speed of either the front or the rear drive shafts overruns, i.e., exceeds, the speed of the other drive shaft by a predetermined value related to the vehicle speed, indicating that wheel slip is present, clutch current is incrementally increased to increase clutch engagement and torque transfer to the secondary axle.

Abstract: An on demand vehicle drive system monitors vehicle performance and operating conditions and controls torque delivery to the vehicle wheels. The system includes a plurality of speed and position sensors, a transfer case having primary and secondary output shafts driving primary and secondary drive shafts, differentials and axles and a microcontroller. The sensors include a vehicle speed sensor, a pair of primary and secondary drive shaft speed sensors, and brake and driveline status sensors. The transfer case includes a modulating electromagnetic clutch comprising a primary, cone clutch assembly which functions as a pilot device to actuate a secondary, disc pack clutch assembly. The electromagnetic clutch is controlled by the microcontroller which is incrementally engaged to transfer torque from the primary output shaft to the secondary output shaft. When the speed of either the front or the rear drive shaft overruns, i.e.

Abstract: A transfer case for a part-time four wheel drive vehicle includes a planetary gear speed reduction assembly driven by the transfer case input shaft for providing high and low speed range outputs. The planetary gear assembly is disposed between and is selectively engaged by primary and secondary clutch collars, the primary clutch driving the rear (primary) output shaft in either the high or low speed ranges. The secondary clutch drives the front (secondary) output shaft through a chain drive in the low range. The clutch collars are controlled by a single (common) clutch operator. An electromagnetic clutch assembly driven by the input shaft selectively drives the front output shaft chain drive. The electromagnetic clutch functions both as a synchronizer and torque delivery device. The transfer case may be combined with a control which facilitates direct selection of vehicle drive mode.

Abstract: A two speed transfer case includes a spring biased dog clutch connecting a shift sleeve to a main input shaft and an electromagnetic friction clutch for transferring torque from the shift sleeve to one of the outputs. This arrangement allows dynamic upshifts and downshifts and modulation of the torque split between the outputs.

Abstract: An on demand vehicle drive system monitors vehicle performance and operating conditions and controls torque delivery to the vehicle wheels. The system includes a plurality of speed and position sensors, a transfer case having primary and secondary output shafts driving primary and secondary axles and a microcontroller. The sensors include a vehicle speed sensor, a pair of primary and secondary drive shaft speed sensors, and brake and driveline status sensors. The transfer case includes a modulating electromagnetic clutch controlled by the microcontroller which is incrementally engaged to transfer torque from the primary output shaft to the secondary output shaft. When the speed of either the front or the rear drive shafts overruns, i.e., exceeds, the speed of the other drive shaft by a predetermined value related to the vehicle speed, indicating that wheel slip is present, clutch current is incrementally increased to increase clutch engagement and torque transfer to the secondary axle.

Abstract: A transfer case for a part-time four wheel drive vehicle includes a planetary gear speed reduction assembly driven by the transfer case input shaft for providing high and low speed range outputs. The planetary gear assembly is disposed between and is selectively engaged by primary and secondary clutch collars, the primary clutch driving the rear (primary) output shaft in either the high or low speed ranges. The secondary clutch drives the front (secondary) output shaft through a chain drive in the low range. The clutch collars are controlled by a single (common) clutch operator. An electromagnetic clutch assembly driven by the input shaft selectively drives the front output shaft chain drive. The electromagnetic clutch functions both as a synchronizer and torque delivery device. The transfer case may be combined with a control which facilitates direct selection of vehicle drive mode.

Abstract: An on demand vehicle drive system monitors vehicle performance and operating conditions and controls torque delivery to the vehicle wheels. The system includes a plurality of speed and position sensors, a transfer case having primary and secondary output shafts driving primary and secondary axles and a microcontroller. The sensors include a vehicle speed sensor, a pair of primary and secondary drive shaft speed sensors, and brake and driveline status sensors. The transfer case includes a modulating electromagnetic clutch controlled by the microcontroller which is incrementally engaged to transfer torque from the primary output shaft to the secondary output shaft. When the speed of either the front or the rear drive shafts overruns, i.e., exceeds, the speed of the other drive shaft by a predetermined value related to the vehicle speed, indicating that wheel slip is present, clutch current is incrementally increased to increase clutch engagement and torque transfer to the secondary axle.