Patent ID: 7766116
Filing Date: 2010-08-03
Classification: B60K,B60Y

Abstract:
1. A four wheel drive vehicle having front and rear wheels, an engine, a power train for supplying torque to the front and rear wheels, the power train having a driving member and a driven member between at least one of the engine and the front wheels, and the engine and the rear wheels, a clutch pack joining the driving and driven members and having an actuator switchable between on and off positions, the actuator, when off, permitting the driven member to turn freely and independently of the driving member and, when on, enabling the clutch pack to respond to predetermined minimum differences in rotational speed between the driving and driven members to lock these members together to deliver torque to the driven member, and including speed sensors sensing a function of the rotational speeds of the rear wheels and the front wheels and a controller for switching the actuator on in response to a sensed predetermined absolute difference between rotational speeds of the front and rear wheels, wherein the clutch pack, when locked, remains locked for as long as torque is continuously transferred from the driving member to the driven member and wherein the controller periodically and momentarily switches the actuator off to enable the clutch pack to unlock if torque is not being transferred to the driven member by the driving member.