| 摘要 |
PURPOSE:To make it possible to control both injection amount and injection timing with a high accuracy and to perform pilot injection as well by making an on-off valve in a return passage actuated to close by an oil pressure applied with a piezoelectric type actuator. CONSTITUTION:When a return passage 24 is closed with a spool valve 25 in the process of pressurinzing fuel in a pump chamber 2 by means of a plunger 3, fuel pressure rises to supply fuel to an injection nozzle 11, and when the return passage is closed on the other hand, the fuel is not supplied. Therefore, by controlling the opening and closing, it is possible to determine the amount and timing of the injection and to perform pilot injection. This valve 25 is capable of rapid action since it is actuated by oil pressure in a large-diametered pressure chamber 32 pressured by the elongation of a piezoelectric element laminate body 35 to which a voltage is applied to elongate. Thus, controlling the injection amount and injection timing during high speed revolution or performing the pilot injection in which on-off actions within a very short period of time are required can be made with high accuracy.
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