| 摘要 |
PROBLEM TO BE SOLVED: To reconcile increasing of injection pressure of a low speed rotating zone and suppressing of smoke in a high load zone by opening one of needle valve when a pressure chamber is switched from an accumulator side to a drain side, leading high pressure fuel in the accumulator to a nozzle chamber, and opening the other needle valve when pressure in the nozzle chamber exceeds valve opening pressure. SOLUTION: When fuel is injected, a three way solenoid valve 21 is switched, an orifice 17 and a drain passage 19 are communicated with each other, fuel in a pressure chamber 14 is discharged from a drain passage 19 to an outside, and fuel pressure is gradually reduced. A needle valve 8 is lifted, a seat part 9 is opened, a nozzle chamber 11 is communicated with the accumulator through an oil sump chamber 10, and high pressure fuel in the accumulator is led to the nozzle chamber 11. When fuel pressure in the nozzle chamber 11 increased more than force of a valve closing direction by a return spring 15 applied to the other needle valve 5, the needle valve 5 is rapidly lifted, the seat part 7 is opened, and fuel is injected from an injection hole 3. It is thus possible to utilize good points of both systems of a common rail type and a jerk type.
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