| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize a fuel injection valve, and to improve responsivity by providing a coil portion generating high frequency around a shape memory alloy actuator in the fuel injection valve injecting fuel according to the shrinkage of the shape memory alloy actuator owing to a change in temperature. SOLUTION: When high frequency current is not carried to a coil 16, the temperature of a shape memory alloy(SMA) actuator 5 is generally equal to the temperature of fuel, so that the actuator 5 is in an extending state, and a needle valve 3 closes an injection port 2. When high frequency current is carried to the coil 16 through a control circuit 17, an induced current (eddy current) is generated in the SMA actuator 5 proportional to a change speed (frequency) of the magnetic flux thereof, and the temperature of the SMA actuator 5 is rapidly raised. When the temperature exceeds transformation temperature, the SMA actuator 5 is shrunk. Consequently, the needle valve 3 is retreated by a return spring 4 to open the injection port 2, thereby conducting fuel injection. Therefore, fuel injection having excellent responsivity is enabled.
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