Patent ID: 9000733
Filing Date: 2015-04-07
Classification: F16K

Abstract:
1. An electric actuator comprising a motor for receiving a supply of electric power from a power supply portion and for driving a valve, and a backup capacitor that is charged through the receipt of electric power from the power supply, for performing a return operation, at the time of a power outage, on the valve to a prescribed opening position through forcibly driving the motor through electrical energy that is stored in the backup capacitor, comprising: a degree-of-opening detecting unit detecting an actual degree of opening of the valve; a terminal voltage detecting unit detecting a terminal voltage of the backup capacitor; an electrostatic capacitance measuring unit measuring periodically a most recent electrostatic capacitance value for the backup capacitor; a required charging voltage calculating unit calculating, as a required charging voltage, a charging voltage for the backup capacitor that is required in order to cause the return operation of the valve from the opening setting value at that time to the prescribed opening position, based on the measured most recent electrostatic capacitance value, each time the most recent electrostatic capacitance value of the backup capacitor is measured; and a charging unit determining a value for an electric current for charging the backup capacitor based on the actual degree of opening of the valve and the opening setting value if the required charging voltage, calculated by the required charging voltage calculating unit, is greater than the terminal voltage detected by the terminal voltage detecting unit, and charging the backup capacitor until the terminal voltage detected by the terminal voltage detecting unit reaches the required charging voltage.