Kenneth F Evans

US Patent:

49863835, Jan 22, 1991

Filed:

Dec 29, 1986

Appl. No.:

6/946959

Inventors:

Kenneth W. Evans - San Diego CA

International Classification:

B60K 600
F15B 102

US Classification:

180165

Abstract:

A variable displacement, hydraulic pump/motor has its rotatable cylinder block concentrically affixed to a drive shaft segment of a self-propelled vehicle, the pump/motor has selected pump and motor modes. An hydraulic accumulator is charged and discharged from the pump/motor when it is in its pump and motor modes, respectively. A fluid reservoir supplies and receives low pressure fluid when the accumulator is being charged and discharged, respectively. Preferably the reservoir is a combination of an aft chamber of the accumulator, a low pressure chamber defined by the pump/motor cylinder block and its housing, and a low pressure fluid path between the two. The pump/motor is unloaded when the vehicle is being operated in reverse or when neither the brake nor accelerator is being actuated. The pump/motor is in the pump mode whenever the vehicle is moving forward and the brakes are applied, and it is the motor mode whenever the vehicle is in forward gear and the accelerator is actuated. The mode of the pump/motor is controlled by a pair of complimentary actuators in a push-pull arrangement which operates a lever connected to a variable pitch yoke and swash plate which set the displacement of pump/motor pistons.