| 摘要 |
PROBLEM TO BE SOLVED: To prohibit the use of an expensive clutch brake for a shutoff valve to hold an valve opening condition, to reduce power loss and the load of a mechanism part, and to prevent the occurrence of water hammering resulting in damage to the valve when closed. SOLUTION: The shutoff valve wherein a spring for energizing the valve in a direction to close the valve is provided on a transmission mechanism via which an output shaft connected with the valve is connected to a DC brushless motor 20, includes a driving circuit 21 for driving the motor 20, and a DC power supply 22. When the valve is opened with the spring being twisted, a direct current is supplied from the DC power supply 22 to the motor 20 and a rotor is attracted by a stator coil to hold a valve opening condition, thus suppressing the rotation of the motor 20 without using the expensive clutch brake to reduce power loss and the load of the mechanism part. The current is controlled during closing the valve (in emergency) to prevent the sudden closing-up operation of the valve 5, thus preventing water hammering. COPYRIGHT: (C)2010,JPO&INPIT
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