Solenoid-Actuated Zero-Leakage Fail-Safe Three-Position Poppet-Style Four-Way Hydraulic Directional Control Valve

Patent No. 6,095,187

Issued: August 1, 2000

Inventor: Thomas W. Hotchkiss, Orange, CT

Assignee: Interface Devices, Inc., Milford, CT

 A solenoid-actuated zero-leakage fail-safe three-position poppet-style four-way hydraulic directional control valve includes an arrangement whereby the inlet pressure P is connected to the inlet ports of first and second normally closed 2-way poppet solenoid valves. The outlets of first and second poppet solenoid valves are connected to the A and B load ports, respectively.

The A and B ports are respectively connected to the checked port of first and second pilot-operated check valves (POCVs) whose outlets are connected to the tank port T. The pilot ports of the POCVs are cross connected from A to B and from B to A. When the solenoid for the first poppet solenoid valve is energized, the first poppet solenoid valve opens, admitting pressure to port A. Pressure is blocked to the tank port by the first POCV. Simultaneously, the pilot pressure from the A-line opens the second POCV, thereby connecting the B port to tank. If power fails, pressure is maintained in the A-line and the B-line remains connected to tank. 

Due to the design of the directional control valve, internal leakage is 5 drops per minute at a maximum operating pressure of 6,000 psi (414 bar) while supporting a high flow of 3.0 gpm (11.4 lpm) nominal.

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