| 摘要 |
<p>1,160,619. Valves. EATON YALE & TOWNE Inc. 17 Oct., 1967 [26 Oct., 1966], No. 47250/67. Heading F2V. [Also in Divisions F1 and G3] In an hydraulic system in which a pump 12 supplies fluid to one or other end of an actuator 10, 11 through a changeover spool valve 14, the velocity of the actuator is controlled by the degree of displacement of the spool 22 and a compensating valve 36 subject to the pressure drop across the valve 14 maintains the flow of fluid to the actuator constant by by-passing excess fluid through a port 56 and by restricting the flow through port 55 to the spool valve 22. The compensating valve 36 comprises a housing 42 having a bore 43 in which is slidable a valve piston 48 controlling communication between an inlet port 54 connected to the pump 12 and the ports 55, 56. One end of the piston valve 48 is urged by a spring 62 and by the pressure of fluid admitted to a chamber 63 connected through a line 35 and a shuttle valve 34 to whichever of the actuator inlet lines 30, 31 is pressurized. The opposite end of the piston 48 is subjected through passages 59, 61 to the pressure at the inlet port 54, whereby if the load on the actuator 10, 11 decreases or the pump outlet pressure increases the pressure drop across the spool valve 22 increases, causing the piston to move to the right. Movement of the piston to the right first connects the inlet port 54 to the by-pass port 56 and secondly a land 50 on the piston 48 restricts flow to the port 55. Fluid by-passed is utilized in a load circuit 57.</p> |
