Reversing means for double-acting fluid pump

Claim 1

A reversible pump comprising a pump housing, a first fluid cavity within said pump housing containing a reciprocable piston dividing said first cavity into first and second portions, first and second port means in said first and second portions, respectively, for the inlet and outlet of fluid, first and second fluid lines connected to said first and second port means, respectively, first and second switch means mounted in said first and second fluid lines, respectively, first and second switch means mounted in said first and second first fluid cavity portions, said first and second switch means being positioned within their respective cavity portions to be actuated by said piston at each end of the reciprocating path, control means connected to said solenoid valves and said switch means for reversing the direction of fluid flow and piston travel as the piston reaches each end of its reciprocating path, said control means comprising a latching relay actuated by signals from said first and second switch means, third and fourth solenoid valves connected in said first and second fluid lines to shut-off simultaneously and completely block fluid flow to and from said reciprocable piston, a second fluid cavity within said pump housing having an inlet and an outlet port, a first check valve in said inlet port to block said inlet port during the pressure stroke, a double-acting, fluid piston connected to said reciprocable piston and forming a portion of said second fluid cavity, and a second check valve in said fluid piston to block off said second fluid cavity from said outlet port during the suction stroke, whereby reciprocating movement of said reciprocable piston causes said fluid piston to produce a pumping action to draw fluid into said second fluid cavity through said outlet port.