Defective-portion detector for fuel injection system

A defective-portion detector for a fuel injection system that is provided with a fuel injector injecting a fuel accumulated in an accumulator and a fuel pressure sensor detecting a fuel pressure in a fuel supply passage from the accumulator to an injection port of the fuel injector, the defective-portion detector comprising:

• a fuel-pressure-waveform detecting portion which detects a variation in the fuel pressure as a fuel pressure waveform based on a detection value of the fuel pressure sensor;
• a fuel-injection-rate parameter computing portion which computes, based on the fuel pressure waveform, a plurality of injection-rate parameters required for identifying an injection-rate waveform corresponding to the fuel pressure waveform;
• a determining portion which determines whether each learning value of the injection-rate parameters is an abnormal value;
• and
• a defective-portion identifying portion which identifies a defective portion in the fuel injection system based on a combination of abnormal learning values which the determining portion has determined, wherein
• a time period from when a fuel-injection-start command is transmitted to the fuel injector until when the fuel injector actually starts to be opened or the fuel injector actually injects the fuel is defined as a fuel-injection-start time delay,
• the injection-rate parameters include at least the fuel-injection-start time delay and an increasing speed of the injection-rate, and
• the defective-portion identifying portion determines that a driving force of an actuator for opening the fuel injector is deteriorated and identifies the actuator as a defective portion when the determining portion determines that the increasing speed of the injection-rate is lower than a predetermined value and the fuel-injection-start time delay is longer than a predetermined time period.

A defective-portion detector for a fuel injection system that is provided with a fuel injector injecting a fuel accumulated in an accumulator and a fuel pressure sensor detecting a fuel pressure in a fuel supply passage from the accumulator to an injection port of the fuel injector, the defective-portion detector comprising:

• a fuel-pressure-waveform detecting portion which detects a variation in the fuel pressure as a fuel pressure waveform based on a detection value of the fuel pressure sensor;
• a fuel-injection-rate parameter computing portion which computes, based on the fuel pressure waveform, a plurality of injection-rate parameters required for identifying an injection-rate waveform corresponding to the fuel pressure waveform;
• a determining portion which determines whether each learning value of the injection-rate parameters is an abnormal value;
• and
• a defective-portion identifying portion which identifies a defective portion in the fuel injection system based on a combination of abnormal learning values which the determining portion has determined, wherein
• a time period from when a fuel-injection-end command is transmitted to the fuel injector until when the fuel injector actually starts to be closed or the fuel injector actually ends a fuel injection is defined as a fuel-injection-end time delay,
• the injection-rate parameters include at least the fuel-injection-end time delay and an decreasing speed of the injection-rate, and
• the defective-portion identifying portion determines that the fuel supply passage is clogged and its flow passage area is decreased and identifies the fuel supply passage as a defective portion when the determining portion determines that the decreasing speed of the injection-rate is higher than a predetermined value and the fuel-injection-end time delay is shorter than a predetermined time period.

A defective-portion detector for a fuel injection system that is provided with a fuel injector injecting a fuel accumulated in an accumulator and a fuel pressure sensor detecting a fuel pressure in a fuel supply passage from the accumulator to an injection port of the fuel injector, the defective-portion detector comprising:

• a fuel-pressure-waveform detecting portion which detects a variation in the fuel pressure as a fuel pressure waveform based on a detection value of the fuel pressure sensor;
• a fuel-injection-rate parameter computing portion which computes, based on the fuel pressure waveform, a plurality of injection-rate parameters required for identifying an injection-rate waveform corresponding to the fuel pressure waveform;
• a determining portion which determines whether each learning value of the injection-rate parameters is an abnormal value;
• and
• a defective-portion identifying portion which identifies a defective portion in the fuel injection system based on a combination of abnormal learning values which the determining portion has determined, wherein
• a time period from when a fuel-injection-end command is transmitted to the fuel injector until when the fuel injector actually starts to be closed or the fuel injector actually ends a fuel injection is defined as a fuel-injection-end time delay,
• the injection-rate parameters include at least the fuel-injection-end time delay and an decreasing speed of the injection-rate, and
• the defective-portion identifying portion determines that a valve-closing mechanism of the fuel injector is faulty and identifies the valve-closing mechanism as the defective portion when the determining portion determines that the fuel-injection-end time delay and the decreasing speed of the injection-rate can not be computed due to a fact that the fuel injection-rate does not start to decrease.