HYDRAULIC DISTRIBUTOR Russian patent published in 2002 - IPC

FIELD: hydraulic distributing systems, for example of machine tools, cranes. SUBSTANCE: hydraulic distributor includes proportional electrohydraulic distributor of control circuit 1, main slide valve 2, centering spring 3, pickup 4 for detecting position of main slide valve, working branches 12,13; main lines 14,15 for supplying and draining respectively; additional slide valve 5. When main slide valve is in operational position, draining working branch is joined with draining main line 15 through intermediate cavity of slide valve 5 whose ends are subjected to action of control pressure at one side and at other side - to pressure of cavity 16 arranged just before regulating edge 8 of main slide valve 2. In the result slide valve 5 slightly opens opening 10 by action of pressure in draining working branch until pressure in cavity 16 achieves pressure value in control cavity 6. Therefore, area of opening of regulating edge 8 and pressure drop onto it are determined only by movement of main slide valve 2. Flowrate of working liquid through hydraulic distributor depends only upon value of control signal which at predetermined characteristics of spring sets control pressure and pressure drop on regulating edge 8. When delivery of pump is insufficient, pressure in cavity 16 is less than control pressure in cavity 6; slide valve 5 moves to stopper by pressure action for mutually connecting cavities 6 and 16. Liquid discharge out of cavity 6 causes increased difference between control signal and signal of pickup 4 detecting position of main slide valve. It is possible to use such increased pressure difference signal for controlling delivery of pump. EFFECT: enhanced reliability of hydraulic distributor. 2 cl,1 dwg