HYDRAULIC PRESSURE CONTROL SYSTEM FOR A PUMP

摘要

A positive displacement pump assembly which has an hydraulically controlled intake check valve that is controlled by a three-way solenoid control valve. The intake valve contains a one-way check valve that opens when the pump piston is on an intake stroke and normally closes when the pump piston is on a power stroke. The check valve further contains an hydraulically controlled piston that can open the check valve during the power stroke so that the output fluid of the pump flows to drain. The piston is controlled by the solenoid control valve. The control valve has a pair of digitally latched solenoids. The output pressure of the pump can be regulated by energizing one of the solenoids and applying hydraulic pressure to the piston to open the check valve during the power stroke of the pump. The pump is preferably a dual piston wobble plate pump that incorporates a pair of hydraulically controlled intake check valves that are both controlled by a single solenoid control valve.