| 摘要 |
PURPOSE: To make cavitation hardly occur and reduce a fluid sound. CONSTITUTION: A worm shaft and a stub shaft are laid on the same axial line and jointed to each other via a torsion bar, so as to be capable of relative rotation at the preset angle. Furthermore, a valve sleeve 32 is formed on the internal surface of the worm shaft and coupled to the external surface of a valve rotor jointed to the stub shaft, thereby forming a rotary valve. Also, three return holes 50 are formed on the sleeve 32 at peripherally equal intervals, and return oil from the rotary valve is circulated to an oil tank via the holes 50. In this case, each of the holes 50 is formed out of two small round holes 50a and 50a adjacent to each other in a circumferential direction, or a circumferential slot. According to this construction, the flow passage area of each hole 50 becomes large. As a result, a flow velocity drops and a flow is facilitated, thereby making cavitation hardly occur.
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