Workload calculation apparatus and method for internal combustion engine, and engine control unit

A workload calculation method for an internal combustion engine, which is for calculating a workload parameter indicative of a workload of the internal combustion engine having a combustion chamber, comprising the steps of:

• setting a first correlation function indicative of an integral of the product of volume data indicating a change state of a volume of said combustion chamber and a reference signal having a predetermined frequency;
• generating the reference signal;
• detecting in-cylinder pressure change amount data indicative of the amount of change in pressure in the combustion chamber;
• calculating, on the basis of the generated reference signal and the detected in-cylinder pressure change amount data, a second correlation function indicative of an integral of the product of the reference signal and the in-cylinder pressure change amount data;
• and
• calculating the workload parameter on the basis of the first and second correlation functions.

An engine control unit including a control program for controlling calculation of a workload parameter indicative of a workload of an internal combustion engine having a combustion chamber, the program causing a computer to:

• set a first correlation function indicative of an integral of the product of volume data indicating a change state of a volume of said combustion chamber and a reference signal having a predetermined frequency;
• generate the reference signal;
• detect in-cylinder pressure change amount data indicative of the amount of change in pressure in the combustion chamber;
• calculate, on the basis of the generated reference signal and the detected in-cylinder pressure change amount data, a second correlation function indicative of an integral of the product of the reference signal and the in-cylinder pressure change amount data;
• and calculate the workload parameter on the basis of the first and second correlation functions.