Combustion timing prediction method for compression self-ignition internal combustion engine, control method for compression self-ignition internal combustion engine, and compression self-ignition internal combustion engine system

A compression self-ignition internal combustion engine system comprising a compression self-ignition internal combustion engine that causes a hydrocarbon fuel in a combustion chamber to perform compression self-ignition and a controller for controlling the internal combustion engine,

• wherein the controller:
• specifies types of a plurality of hydrocarbon components contained in the hydrocarbon fuel and proportions of the respective types in the hydrocarbon fuel;
• calculates, on the basis of a temperature in the combustion chamber of the internal combustion engine, a value of a first function serving as a function of the temperature for each of the specified types;
• calculates, on the basis of the proportion and the first function relating to each of the types, a value of a second function, which is a function that increases in value in response to an increase of the value of the first function and/or the proportion, for each of the specified types;
• integrates the values of the second function relating to the respective types;
• predicts, on the basis of the integrated value of the values of the second function, the combustion timing of the hydrocarbon fuel in the internal combustion engine to be steadily later as the integrated value increases;
• and
• controls a control parameter of the internal combustion engine on the basis of the predicted combustion timing.