| 摘要 |
PURPOSE:To improve reliability by providing a driver circuit with a detecting means detecting the quantity of charges charged to a piezoelectric element and controlling the output voltage of the driver circuit in response to the detection of the detecting means. CONSTITUTION:A piezoelectric element 10 is used for a fuel injection valve for an internal combustion engine, and injects fuel into a combustion chamber. The element 10 is connected to a variable voltage power 40 by a charging circuit including a first switching element 42 composed of a thyristor and a first coil 44 in a drive for the piezoelectric element 10. The first coil 44 forms a resonance circuit to the capacity of the piezoelectric element 10, and generates resonance currents. A capacitor 46 for detecting voltage is arranged in series with the piezoelectric element 10 to the charging circuit, and a voltage detecting means 48 is provided. A discharge circuit is formed to the piezoelectric element 10, and said circuit is constituted of a second switching element 50 consisting of a thyristor and a second capacitor 52 for resonance. The first and second switching elements 42, 50 are trigger-controlled by a trigger circuit 54 by a controller 56. |
