| 摘要 |
1,222,779. Valves. KOEHRING CO. Inc. 11 Nov., 1969 [14 Nov., 1968], No. 55179/69. Heading F2V. A spool valve for controlling hydraulic flow between pump 7, reservoir R and motor 6 is arranged to maintain a constant flow rate to the selected end of the motor which is determined solely by the direction and amount of movement imparted to the spool. Land 25 has tapered grooves 30, 31 which throttle flow between inlet passage 10 and feeder passage 11 in accordance with the degree of movement of the spool, and the pressures in these passages are communicated to opposite sides of a piston closure member 34 which is urged to the " open " position shown by a spring 40. In operation pressure fluctuations in passage 10 change the pressure drop across the operative groove 30 or 31 so causing member 34 to move to a position to maintain a constant rate of flow to the selected service passage 15 or 16 via load holding check valve 14. A similar arrangement, comprising groove 43 and closure member 48, regulates exhaust flow from outlet 42. Figs. 2-7 (not shown) illustrate modified arrange ments for achieving a constant flow rate. |
