Patent Document ID: 9127612
Application ID: 13325531
Patent Flag: 1

Claim One:
1. A system comprising: a fuel injector for injecting the high-pressure fuel accumulated in a accumulator through a fuel injection port; a memory for storing a fuel-injection-characteristic value which the fuel injector individually has; a fuel pressure sensor provided in a fuel passage fluidly connecting the accumulator and the fuel injection port, the fuel pressure sensor being configured to detect a fuel pressure in the fuel passage; a fuel temperature sensor for detecting a fuel temperature; an electronic control unit (ECU) configured to: generate a fuel-injection command signal based on the fuel-injection-characteristic value; analyze a fuel injection condition based on a fuel pressure waveform which represents a variation in a detection value of the fuel pressure sensor, the fuel-injection-characteristic value being detected based on the analyzed fuel injection condition; store the fuel-injection-characteristic value in the memory in association with the fuel temperature detected by the fuel temperature sensor; wherein the memory stores a characteristics formula representing a relationship between the fuel-injection characteristic value and the fuel temperature; the electronic control unit is further configured to update the characteristics formula based on the detected fuel-injection-characteristic value; when a difference between the detected fuel-injection-characteristic value and an unlearned fuel-injection-characteristic value stored in the memory is less than a specified value, the electronic control unit updates the characteristics formula into a characteristics formula which is offset by the difference; when the difference between the detected fuel-injection-characteristic value and the unlearned fuel-injection-characteristic value stored in the memory is not less than the specified value, the electronic control unit updates the characteristics formula into a characteristics formula of which inclination is varied according to the difference; and the electronic control unit is further configured to compute the fuel-injection-characteristic value according to the characteristics formula.