Patent ID: 6631779
Filing Date: 2003-10-14
Classification: B60K,B60W,F16D,F16H

Abstract:
An adaptive four-wheel vehicle drive system comprising, in combination,a primary drive assembly including a primary differential, primary axles and primary drive wheels, a secondary drive assembly including a secondary differential, secondary axles and secondary drive wheels, a transmission for providing torque to said primary drive assembly, an electromagnetic modulating clutch for selectively transferring torque from said primary drive assembly to said secondary drive assembly, said electromagnetic modulating clutch including a disc pack assembly, an electromagnetic coil, and an operator including at least one cam surface operable to compress said disc pack assembly, at least one first sensor for providing a rotational speed of said primary drive assembly, at least one second sensor for providing a rotational speed of said secondary drive assembly, and a microcontroller for comparing said rotational speed of said primary drive assembly with said rotational speed of said secondary drive assembly and repeatedly incrementing an output to engage said modulating clutch while a difference between said rotational speeds is greater than a first predetermined value and repeatedly decrementing said output to disengage said modulating clutch when said difference is less than a second predetermined value, said incrementing output defining at least eight steps having a duration of about 30 milliseconds.