Denso Corporation

Naoki Mikami

Naoyuki Yamada

A fuel injection system is provided with a pressure accumulator accumulating a high pressure fuel, a fuel pump supplying the high pressure fuel to the pressure accumulator, a fuel injector injecting the high pressure fuel, and a fuel pressure sensor detecting a fuel pressure in a fuel passage between the pressure accumulator and an injection port of the fuel injector. An ECU includes a fuel pressure obtaining portion which obtains the fuel pressure detected by the fuel pressure sensor, a differential value calculating portion which differentiates the fuel pressure obtained by the fuel pressure obtaining portion so as to calculate a fuel pressure differential value, and an end timing calculating portion which calculates an injection end timing at which the fuel injector terminates a fuel injection.

Fuel injection control device

A pulsation detection unit detects, as an actual characteristic, a pulsation frequency of a pressure pulsation, which is caused in fuel pressure, or a physical quantity corresponding to the pulsation frequency, according to a sensor signal from a pressure sensor. The pressure sensor detects a fuel pressure of fuel supplied to a fuel injection valve, which is equipped to an internal combustion engine. A storage unit stores, as a reference characteristic, a reference frequency of a predetermined reference pulsation or a physical quantity corresponding to the reference frequency. A density detection unit detects a fuel density according to a quantity of deviation between the reference characteristic, which is stored in the storage unit, and the actual characteristic, which is detected with the pulsation detection unit.

Fuel density detection device

A fuel injection system has a common rail storing fuel, a fuel injector injecting the fuel, a fuel-passage supplying the fuel to the fuel injector, and a fuel-pressure sensor detecting a fuel pressure. An ECU acquires a waveform of a fuel pressure representing a change of a fuel pressure based on the detected fuel pressure at the fuel injection. The ECU calculates a speed of a fuel pressure wave forming the waveform of the fuel pressure based on a period of a pulsation of the waveform of the fuel pressure and a fuel passage length, and a fuel density based on the speed of the fuel pressure wave. The ECU further calculates a fuel cetane number, and a kinematic viscosity of the fuel based on the fuel density and the fuel cetane number. The ECU judges fuel properties based on the kinematic viscosity of the fuel.

Growing community of inventors

Takahama, Japan

Naoki Mikami