Fuel combustion rate determining method for e.g. direct injection oil engine, involves storing rotation angle of crankshaft as angular value of combustion rate if threshold values respectively exceed and does not exceed angle

摘要

The method involves evaluating a variable at a rotation angle of a crankshaft in a combustion chamber of a cylinder for each of displacement cycles of a piston in the cylinder. The variable is compared with a threshold value above which combustion of fuel is not initiated. A modulus difference between the variable and another variable evaluated for another angle is compared with another threshold value. The former angle is stored as an angular value of combustion rate for the cycle if the threshold values respectively exceed and does not exceed the former angle. An independent claim is also included for a method for estimating cetane index of fuel injected in an internal combustion engine.