| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that, since the valve operating torque required for opening and closing a valve varies depending on the opening of the valve, the maximum value of the valve operating torque need to be considered; and, to cope with this, conventionally, an actuator for driving a valve whose motor output torque exceeds the above maximum value of operating torque is selected or the reducing ratio of a motor output-side reducing mechanism is increased and this poses various problems, such as increase in size of entire equipment. SOLUTION: The capacitance of a capacitor installed in a motor M is varied by closing and opening a limit switch LSW connected with an additional capacitor C2, for example, in response to the rotational angle of a valve driving shaft. The output torque of the rotor 10 of the motor M can be varied by this variation in the capacitance of the capacitor, and thus, the output torque of the valve driving shaft of an actuator for driving a valve coupled with the rotor 10 can be varied. |
