Patent ID: 9157389
Filing Date: 2015-10-13
Classification: F02D

Abstract:
1. An apparatus of estimating fuel state being applied to a fuel injection system having an injector which injects fuel for combustion in an internal combustion engine; a pressure accumulation container which contains pressurized fuel and supplies the pressurized fuel to the injector; a fuel pressure sensor configured to detect a fuel pressure in a branch passage, which is branched from a main passage extending between an outlet of the pressure accumulation container and a nozzle hole of the injector; and a fuel temperature sensor configured to detect a branch fuel temperature in the branch passage, the apparatus comprising: a main extraction section which extracts a main waveform component from a pressure waveform detected by the fuel pressure sensor, the main component being a component in the pressure waveform and caused by pressure vibration traveling in the main passage; a branch extraction section which extracts a branch waveform component from the pressure waveform, the branch component being a component in the pressure waveform and caused by pressure vibration traveling in the branch passage; a branch velocity calculation section which calculates a branch velocity, which is a velocity of pressure wave traveling in the branch passage, based on the branch waveform component; a main velocity calculation section which calculates a main velocity, which is a velocity of pressure wave traveling in the main passage, based on the main waveform component; an average pressure calculation section which calculates an average pressure of fuel supplied to the injector based on the pressure waveform; and a fuel state estimation section which estimates a main fuel state, which is fuel state relating to fuel in the main passage, based on the branch fuel temperature, the branch velocity, the main velocity, and the average pressure.