| 摘要 |
A rotary valve (10) is adapted to be associated with a fluid source (P) and a fluid return (R), and is adapted to control the flows of fluid (via control ports C1 and C2) with respect to the opposed chambers of a fluid-powered load. The valve has a body (11) provided with an elongated bore (12). The body has a plurality of passageways (23, 24, 25, 26) communicating spaced locations along the bore with the source, return and load control ports, respectively. A spool member (28) is rotatably mounted in the bore. The spool member has a passage adapted to cooperate with a body passageway so as to define at least one flow-metering port therebetween. The area of this flow-metering port or orifice (34) is a function of the angular displacement of the spool member relative to the body from a null position. The improvement comprises each of the upstream approach walls (32, 35) adjacent the orifice being relieved at an angle ( beta ) of at least 21 DEG with respect to a radial plane so as to cause the flow through the orifice, whether directed inwardly or outwardly, to be substantially radial, thereby to eliminate tangential Bernoulli reaction forces acting on the spool member.
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