Digital electro-hydraulic valve arrangement

摘要

Electro-hydraulic valve arrangements are useful in controlling a displacement control member of a variable displacement pump or motor. However, previous digital electro-hydraulic valves having brief pulse widths required special high speed solenoids to speed up the response time of the valve and resulted in increased cost of the valve. The subject digital electro-hydraulic valve arrangement includes a pair of on/off solenoid actuated valves arranged in series so that a flow path is initiated by a first of the valves and is disrupted by the second valve. The response times of the valves are equal such that directing an electrical signal to the second valve during the response time of the first valve results in extremely brief pulse widths of the valve arrangement. Using two solenoid actuated valves in this manner permits the use of less costly solenoid valves to provide very brief pulse widths through the total valve arrangement.