University of Minnesota

Evan D Sand

Perry Y Li

Devices and methods for improving the efficiency of an axial piston hydraulic motor or other axial piston hydraulic device. In some embodiments, a valve cam, with specified geometry, is assembled to a conventional axial piston hydraulic device (e.g., hydraulic motor, hydraulic pump, hydraulic pump-motor) in a manner permitting selective rotation of the valve cam relative to the distributor valves (e.g., spool valves). The rotating valve cam facilitates variable piston stroke and can be provided in conjunction with (e.g., joint control) an adjustable swashplate according to a mathematical relationship in order to adjust the displacement of the axial piston hydraulic motor (or other device) while maintaining optimal pre-compression and decompression across a range of operating conditions. This configuration allows, for each desired effective displacement of the hydraulic motor, a set of optimal valve timing to achieve perfect pre-compression and decompression so as to eliminate associated throttling losses.

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Minneapolis, MN, United States of America

Evan D Sand