Modular, Electric Shift Transfer Case for Four Wheel Drive Vehicles

A modular part time transfer case was designed and developed using a single variable reluctance electronically controlled inboard electric motor to shift both the high-low range, and from 2-wheel drive to 4-wheel drive.

The modular construction helps to minimize the weight of the transfer case assembly, provides for the adaptation of either a reduction ratio or an over-drive ratio with minimal modification of the transfer case housing; and provides for easy adaptation to difference transmissions. The design is such that the case can fit under very compact vehicle floorpan layouts.

The compact size of the transfer case assembly was made possible by placing the electric motor inside the transfer case housing and enabling one motor to change the gear ratios and synchronize the shift into four wheel drive.

The brushless motor is electronically controlleld and has a built in feedback circuits to maintain control of the rotor position at all times.