An apparatus and method of operating an adaptive drive system of a motor vehicle which reduces drive line wear, improves safety margins and permits weight reduction in drive line components activates a clutch between a primary and secondary drive line when the vehicle is determined to be heavily loaded. The method steps include sensing the position of a throttle position sensor, sensing the instantaneous speed of a motor vehicle and computing instantaneous acceleration, determining whether the ratio of vehicle acceleration to throttle position is less than predetermined threshold value and engaging a transfer case clutch to transfer drive torque from a primary drive line to a secondary drive line. Operation of this method is transparent to the driver inasmuch as the clutch is activated when the vehicle is heavily loaded as determined by the throttle position to acceleration ratio.
Mark A. Perlick - Shelby Township MI Dan J. Showalter - Plymouth MI Roger J. Wood - Cortland NY
BorgWarner, Inc. - Auburn Hills MI
192 566, 192 551, 192 563, 192105 B, 464 46
A yaw damper for a front wheel drive vehicle provides torque transfer between the two non-driven wheels and generates a damping yaw moment in opposition to the current vehicle yaw condition. The yaw damper is passive and includes a mechanical clutch or fluid connection between the two non-driven wheels which transfer yaw correcting torque. The mechanical clutch includes first and second pluralities of interleaved friction disks which are coupled by shafts to respective non-driven wheels. A spring compresses the clutch pack and limits torque transfer between the shafts and wheels to a pre-selected maximum torque. In another embodiment, positive displacement pumps driven by each of the non-driven wheels are connected in series and transmit torque in proportion to the speed difference. In another embodiment, nested shafts include centrifugal clutches which transfer torque in proportion to vehicle speed and difference.
Will Watson - Southfield MI Alan L. Miller - Ithaca NY Drew A. Sundquist - Canton MI Roger T. Simpson - Ithaca NY Diane K. Ducklow - Farmington MI Joseph W. Beckerman - Livonia MI Dan J. Showalter - Plymouth MI
BorgWarner, Inc. - Auburn Hills MI
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. When wheel slip is reduced below the predetermined value the current to the clutch is incrementally reduced.
Ball Ramp Clutch Having Force Amplifying Configuration
A preferred embodiment compound ball ramp clutch assembly for motor vehicle drive line components includes a force amplifying assembly having two ball ramp operators arranged in tandem. The clutch assembly includes a first ball ramp operator having opposed cam plates with load transferring balls, an electromagnetic coil, a rotor and an armature. When energized, the coil creates drag which causes separation of the plates of the first ball ramp operator which compresses a primary (pilot) clutch pack disposed in mechanical parallel with the cam plates and load transferring balls of a second ball ramp operator. A speed difference and drag across the second ball ramp operator compresses a secondary (main) clutch pack. Significantly increased torque carrying capacity is exhibited by such a compound or a tandem ball ramp clutch assembly.
A shift assembly for a two-speed transfer case utilizes a single actuator to drive both the speed range selection mechanism and a modulating friction clutch pack which selectively transfers drive torque from a primary output to a secondary output. The shift assembly includes an actuator which rotates a shift rail and cam having an intermediate helical track and a dwell region at each end. A lost motion assembly operating in conjunction with the helical cam selectively engages and disengages the clutch when the cam follower is in one of the two dwell regions. Thus, the shift assembly provides sequential operation from full clutch engagement in a first speed range, clutch disengagement in the first speed range, de-selection of the first speed range, selection, and de-selection of neutral, selection of a second speed range and, up to full engagement of the clutch in the second speed range.
Electromagnetic Clutch Assembly Having Enhanced Torque Throughput
Dan Joseph Showalter - Plymouth MI, US Christopher John Kowalsky - Windsor, CA
BorgWarner, Inc. - Auburn Hills MI
F16D 1304 F16D 27115
192 35, 192 847
An electromagnetic clutch assembly having a ball ramp operator provides enhanced torque throughput capability. The electromagnetic clutch assembly includes a primary or pilot friction clutch pack and a secondary or main friction clutch pack. A ball ramp operator which is actuated by the primary or pilot friction clutch pack includes a plastic washer or annulus adjacent one of the operator members. The plastic washer provides feedback which enhances the operation of the primary friction clutch pack, augments the compressive force applied to the secondary or main clutch pack and thus increases the torque throughput capability of the electromagnetic clutch assembly.
A shift assembly for a transfer cases, manual and semi-automatic transmissions comprises a drive motor having a worm gear output which engages and drives a gear having an eccentric drive pin disposed parallel to and offset from the axis of a rotation of the gear. The drive pin engages a slot in a shift fork which extends normal to the axis of movement of the shift fork and associated speed change or gear shift mechanism. The shift fork is disposed upon and supported by a shift rail. Uni-directional or bi-directional rotation of the drive motor rotates the gear and sequentially moves the eccentric pin, shift fork and shift mechanism between first and second terminal positions and, typically, a center or intermediate, neutral position.
A variable biasing differential provides an adjustable torque bias between two outputs. An input shaft provides drive torque to a carrier which receives a plurality of stub shafts and a like plurality of planet gears. A first set of planet gears drives a first sun gear and first output and a second set of planet gears, which, in turn, drives additional planet gears which drive a second sun gear and second output. Secured to both ends of the carrier are first and second ring gears which each mesh with an eccentric gear which in turn includes an eccentric second ring gear which meshes with an internal gear disposed about the first and second outputs. These gears are coupled to respective first and second friction clutches which can be independently activated to adjust the torque bias of the differential.