Fuel injection detecting device

A fuel injection detecting device detecting a fuel injection condition, the fuel injection detecting device being applied to a fuel injection system in which a fuel injector injects a fuel accumulated in an accumulator, the fuel injection detecting device comprising:

• a fuel pressure sensor provided in a fuel passage fluidly connecting the accumulator and a fuel injection port of the fuel injector;
• the fuel pressure sensor detecting a fuel pressure which varies due to a fuel injection from the fuel injection port;
• a falling-modeling means for modeling a falling waveform by a falling-modeling function;
• a rising-modeling means for modeling a rising waveform by a rising-modeling function;
• an intersection pressure computing means for computing an intersection pressure at an intersection point of a first line expressed by the falling-modeling function and a second line expressed by the rising-modeling function;
• a reference pressure computing means for computing a reference pressure based on a fuel pressure right before the falling waveform is generated;
• and
• a determination means for determining whether a pressure difference between the reference pressure and the intersection pressure is smaller than or equal to a specified value;
• and
• a maximum fuel injection rate computing means for computing a maximum fuel injection rate based on the specified value without respect to the intersection pressure when the pressure difference between the reference pressure and the intersection pressure is greater than the specified value