| 摘要 |
PURPOSE:To prevent fuel from penetrating a piezoelectric element laminated body even after the longterm use of a pilot injection device by providing a relief groove which collects the fuel raiding into a sliding part between a casing and a piston and lets the above-mentioned fuel go into a low pressure fuel part, and a fuel passage. CONSTITUTION:High pressure fuel pressurizedly fed by a plunger 6 penetrates a clearance between the inner periphery 31a of a casing 31 and the outer periphery 41a of a piston 41. The high pressure fuel penetrated the clearance is first collected in a relief groove 42, and flows toward a fuel collecting chamber 36 through a fuel passage 43 when fuel pressure gradually rises to exceed pressure in the fuel collecting chamber 36. The fuel flowed into the fuel collecting chamber 36 is returned to the side of an intake port 8 through a communicating hole 37. Consequently, even when the piston 41 is slided for the longterm use of a pilot injection device, the fuel can never penetrate a piezoelectric element laminated body 45, and the occurrence of leakage due to the penetration of the fuel can be therefore prevented.
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