Patent ID: 8731799

Claim:
A pre-ignition estimation/control device for an internal combustion engine, comprising: an intake air temperature sensor for detecting a temperature of intake air to be introduced into a combustion chamber; a water temperature sensor for detecting a coolant temperature of the internal combustion engine; a fuel filling sensor for detecting a flow of a fuel in a fuel filler opening; knock detection means for detecting a change of the internal combustion engine caused by a knock and pre-ignition; an intake-cam variable phasing system for changing opening/closing timings of an intake valve by changing a phase of an intake cam; octane number estimation means for estimating an octane number of the fuel based on detection signals received from the intake air temperature sensor, the water temperature sensor, the fuel filling sensor, and the knock detection means; a pre-ignition-occurrence-index calculation module for calculating a total pre-ignition occurrence index based on the detection signals received from the intake air temperature sensor and the water temperature sensor, and the octane number estimated by the octane number estimation means; a pre-ignition-occurrence-index correction module for correcting, when the pre-ignition is detected, the total pre-ignition occurrence index so as to cause the pre-ignition more likely to occur; an effective-compression-ratio-boundary calculation module for calculating a boundary of an effective compression ratio based on the total pre-ignition occurrence index obtained by the pre-ignition-occurrence-index correction module; an intake-cam-phase-advance calculation module for calculating a phase advance of the intake cam based on an operation condition and the boundary of the effective compression ratio calculated by the effective-compression-ratio-boundary calculation module; and an intake-cam-phase control module for controlling the intake-cam variable phasing system based on the phase advance of the intake cam output from the intake-cam-phase-advance calculation module, to thereby restrict a change in the phase advance of the intake cam.