Heat release rate waveform generating device and combustion state diagnostic system for internal combustion engine

摘要

In a diesel engine, an inside of a cylinder is divided into intra-cavity and extra-cavity regions. Ideal heat release rate waveform models, each formed of an isosceles triangle in which each oblique line gradient is a reaction rate, an area is a reaction amount and a base length is a reaction period with a reaction start temperature as a base point, are generated respectively for a vaporization reaction, low-temperature oxidation reaction, thermal decomposition reaction and high-temperature oxidation reaction of injected fuel for each region. An ideal heat release rate waveform of the reaction modes is generated by smoothing the ideal heat release rate waveform models through filtering and combining the ideal heat release rate waveforms, and is compared with an actual heat release rate waveform obtained from a detected in-cylinder pressure. A reaction mode having a deviation larger than or equal to a predetermined amount is diagnosed as being abnormal.

主权项

1. A heat release rate waveform generating device for a compression self-ignition internal combustion engine that carries out self-ignition combustion of fuel injected from a fuel injection valve into a cylinder, the heat release rate waveform generating device comprising:
an electronic control unit configured to: (a) divide an inside of the cylinder into an internal region inside a cavity provided in a piston and an external region outside the cavity, (b) generate an ideal heat release rate waveform for at least one of the regions, the fuel injected from the fuel injection valve being present in the region, (c) generate the ideal heat release rate waveform for the internal region inside the cavity when the fuel injected from the fuel injection valve is present only in the internal region inside the cavity, (d) generate the ideal heat release rate waveform for the external region outside the cavity when the fuel injected from the fuel injection valve is present only in the external region outside the cavity, and (e) individually generate the ideal heat release rate waveform for each of the internal region inside the cavity and the external region outside the cavity when the fuel injected from the fuel injection valve is present in both the internal region inside the cavity and the external region outside the cavity.