| 摘要 |
A unit injector comprising a plunger, a high pressure fuel chamber defined by the tip face of plunger, and a fuel supply port open to the high pressure fuel chamber when the plunger is at the fuel compressing operation start position. A variable volume chamber filled with fuel is provided, and the volume of the variable volume chamber is controlled by a piezoelectric element. A spill valve is also provided for spilling out the fuel in the high pressure fuel chamber to stop the fuel injection, and is controlled by the fuel pressure in the variable volume chamber. A fuel charging port connected to the variable volume chamber is open to the plunger bore at a position remote from the tip face of the plunger on a side opposite to the high pressure fuel chamber, and the variable volume chamber is charged with fuel via the fuel charging port. A fuel trapping chamber is formed between the plunger and the plunger bore at a position between the fuel supply port and the fuel charging port to trap fuel leaked from the high pressure fuel chamber.
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