| 摘要 |
<p>1,240,192. Valves. WEBSTER ELECTRIC CO. Inc. 17 July, 1968 [18 Aug., 1967], No. 34095/68. Heading F2V. [Also in Division F1] An hydraulic valve assembly for controlling the direction and speed of a motor 16 comprises a housing 26 having an inlet passage 50 supplied by a pump 12, a priority flow passage 72 leading to the motor and receiving fluid from the inlet 50 in dependence of the size of a variable restricted orifices 68 or, 70, and an excess flow passage 62 controlled by a plunger valve 42 responsive to the pressure drop across the variable orifices. The variable orifices 68, 70 are in the form of arcuate recesses cut in the surface of a spool valve 22 having lands 22b, 22c controlling the connection between motor ports 86, 88, return ports 98, 100 and a central supply chamber 84. The supply chamber 84 receives fluid from the priority passage 72 via radial ports 78 and an axial passage 76 in the plunger valve 42. When the spool valve 22 is displaced from its spring- urged neutral position shown, flow into the priority passage is established through the orifices 68 or 70 at a rate proportional to the spool displacement. This flow is maintained constant by the plunger valve 42. The plunger has its left hand end acted upon by fluid supplied through a plunger passageway 104 from the inlet 50 and its right-hand end acted upon by fluid downstream of the orifices. This pressure differential acts on the plunger against a spring 46 and takes up an equilibrium position wherein the flow to the excess flow passage 62 is throttled by the land 42a and the flow to the supply chamber is throttled by a land 42b. If the spool valve 22 is in the neutral position shown the pressure acting on the right hand of the plunger 42 collapses through passages 106, 110 leading to outlet 102. Thus the complete pump output flows through the excess flow port 62.</p> |
