| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize a joint by providing a check ball closing a drain hole with oil pressure and a temperature switch pressing the ball to open the drain hole at a prescribed temperature or higher in a high-pressure chamber which communicates with a rotary valve discharge port. SOLUTION: A high-pressure chamber 28 communicated with a discharge port is formed on a rotary valve 11, a tapered valve seat 38 is provided here, and a drain hole 39 is formed. When the temperature is below a prescribed value, a temperature switch 41 is not operated, and a ball 40 is pressed to the valve seat 38 by discharge pressure to close the drain hole 39. When the temperature becomes the prescribed value or above, the switch 41 pushes up the ball 40 to open the drain hole 39. Oil flows to the low pressure side through the drain hole 39 as shown by an arrow (b). If the contact area A between the ball 40 and the drain hole 39 is made small, the force of the switch 41 for pushing the ball 40 can be reduced. The switch 41 is made small, a joint can be miniaturized, the design change of the switch 41 is not required, even when the other hydraulic control system is changed.
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