Control device of compression-ignition engine

A method of implementing control logic of a compression-ignition engine, the engine comprising:

• a fuel injection part configured to inject fuel to be supplied in a combustion chamber;
• a variable valve operating mechanism configured to change a valve timing of an intake valve;
• an ignition part configured to ignite a mixture gas inside the combustion chamber;
• a supercharger configured to boost gas introduced into the combustion chamber;
• a measurement part configured to measure a parameter related to an operating state of the engine;
• and a control part configured to perform a calculation according to a control logic corresponding to the operating state of the engine, in response to the measurement of the measurement part, and output a signal to the fuel injection part, the variable valve operating mechanism, the ignition part, and the supercharger, the control part outputting the signal to the fuel injection part, the variable valve operating mechanism and the supercharger so that a gas-fuel ratio (G/F) that is a weight ratio of the entire gas of the mixture gas inside the combustion chamber to the fuel becomes leaner than a stoichiometric air fuel ratio, and an air-fuel ratio (A/F) that is a weight ratio of air contained in the mixture gas to the fuel becomes the stoichiometric air fuel ratio or richer than the stoichiometric air fuel ratio, while causing the supercharger to boost, and outputting the signal to the ignition part so that an unburnt mixture gas combusts by self-ignition after the ignition part ignites the mixture gas inside the combustion chamber, the method of implementing the control logic, comprising the steps of:
• determining a supercharging pressure P by the supercharger;
• and
• determining the control logic defining a close timing IVC of the intake valve,
• wherein, when determining the control logic, the close timing IVC (deg.aBDC) is determined so that the supercharging pressure P (kPa) satisfies the following expression:
• P≥8.0×10−11IVC6−1.0×10−8IVC5+3.0×10−7IVC4−4.0×10−6IVC3+0.0068IVC2−0.3209IVC+116.63.