Patent ID: 8210155

Claim:
A method of controlling an accumulation chamber pressure in an accumulator fuel injection apparatus, which comprises an accumulation chamber for storing a fuel under pressure, a fuel injection nozzle for injecting the fuel in the accumulation chamber into an internal combustion engine, and a fuel pump for pumping the fuel to the accumulation chamber, an accumulator fuel injection apparatus controlling a pump discharge amount of the fuel pump to bring a fuel pressure prevailing in the accumulation chamber to a target pressure, wherein the method comprises the steps of: calculating a pump discharge command value of the fuel pump by using feedback, based on a pressure difference between an actual accumulation chamber pressure detected by a fuel pressure sensor and the target pressure of the accumulation chamber; producing a numerical model of the pump discharge command value of the fuel pump, a disturbance pressure acting on the accumulation chamber, and accumulation chamber pressure using a transfer function of the fuel pump; estimating a pressure of the disturbance from the numerical model; deriving a compensation value to compensate for the disturbance by using a disturbance observer; and correcting an output calculated by the feedback with the disturbance compensation value derived by the disturbance observer.