Electric actuator
AssigneeAzbil Corporation
InventorHiroaki Narita
Life of this patent
Estimating the term…
Abstract
A most recent electrostatic capacitance value for a backup capacitor is measured periodically. Each time the most recent electrostatic capacitance value is measured, a charging voltage (a required charging voltage) that is required in order to cause a return operation of a valve from the setting opening at that time to an emergency opening/closing position (for example, the fully closed position) is calculated based on the electrostatic capacitance value that has been measured. If the required charging voltage that has been calculated is higher than the terminal voltage that has been detected, then a value for a charging current value is determined based on the actual degree of opening and the setting opening of the valve, and the backup capacitor is charged until the terminal voltage reaches the required charging voltage.
Claims4
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.
Dependencies are inferred from the claim text.