| 摘要 |
PROBLEM TO BE SOLVED: To provide a fuel property determination device and a fuel property determination method capable of promptly determining a fuel property.SOLUTION: A fuel injection system includes a pressure accumulation unit 42 accumulating and holding fuel; a fuel injection valve 10 injecting fuel from an injection hole 11b; fuel passages 42, 11a circulating the fuel from the pressure accumulation unit 42 to the injection hole 11b; and a fuel pressure sensor 20 detecting a fuel pressure. An ECU 30 acquires a pressure waveform indicating a change in the fuel pressure on the basis of the fuel pressure detected by the fuel pressure sensor 20 at a time of injecting the fuel by the fuel injection valve 10, calculates a velocity of a pressure wave forming the pressure waveform on the basis of a pulsation cycle of the pressure waveform and a length of the fuel passages 42, 11a, calculates a density of the fuel on the basis of the velocity, calculates a kinetic viscosity of the fuel on the basis of the density and a cetane number of the fuel, and determines a property of the fuel on the basis of the kinetic viscosity. |
