Patent ID: 8061331

Claim:
A fuel injector for an internal combustion engine, the fuel injector comprising: a high pressure pump for pressure feeding high pressure fuel of the internal combustion engine; a fuel rail for accumulating the fuel which is pressure fed by said high pressure pump; an injection valve for injecting the fuel accumulated in said fuel rail into a cylinder; pressure detection means for detecting the pressure of the fuel accumulated in said fuel rail; target value calculation means for calculating a target value of the fuel pressure in said fuel rail; an electromagnetic relief valve for discharging the pressure accumulated fuel in said fuel rail; and control means used for repeating opening and closing of the relief valve to relieve the fuel pressure in stages so that the fuel pressure in said fuel rail is decreased down to the target fuel pressure, wherein said control means changes a relief valve opening/closing time in a time series manner, and wherein said control means sets a relief valve opening time such that the opening time is long at first and gradually decreases thereafter.