Patent ID: 6330874
Filing Date: 2001-12-18
Classification: F02P,Y02T

Abstract:
A cylinder-selective knock control method for an internal combustion engine, which comprises:defining, in association with a respective operating point that depends on a load and an engine speed, a cylinder-selective ignition angle from a predetermined cylinder-selective basic ignition angle associated with knock-free operation and a cylinder-selective knock adjustment angle that increases stepwise with a predetermined step size in a retarded direction each time a knock occurs and decreases stepwise with a predetermined step size in an advanced direction after each engine cycle during knock-free operation;determining a cylinder-selective first adaptation value of a first adaptation circuit from a comparison of the knock adjustment angle with a first and a second threshold value;wherein the first threshold value is greater than the step size, specified in the retarded direction, of the cylinder-selective knock adjustment angle, and the second threshold value is less than the step size, specified in the retarded direction, of the cylinder-selective knock adjustment angle;modifying the cylinder-selective adaptation value of the first adaptation circuit in the retarded direction with a predetermined first adaptation step size after each engine cycle for as long as the knock adjustment angle is greater in terms of an absolute value thereof than the first threshold value;holding the cylinder-selective adaptation value of the first adaptation circuit constant for as long as the knock adjustment angle is less than the first threshold value and greater than the second threshold value in terms of the absolute value; andmodifying the cylinder-selective adaptation value of the first adaptation circuit in the advanced direction with a predetermined second adaptation step size for as long as the knock adjustment angle is less in terms of the absolute value than the second threshold value;determining a second adaptation value, associated with all the cylinders, of a second adaptation circuit from a comparison of the average value of all the cylinder-selective adaptation values of the current operating point with a predetermined threshold; andusing the cylinder-selective first adaptation value and the second adaptation value associated with all the cylinders to form a cylinder-selective total ignition angle in accordance with the formulaZW(z)=GZ(z)-KNK(z)-AD1(z)-AD2where z is a number of the cylinder, ZW is the total ignition angle, GZ is the basic ignition angle, KNK is the knock adjustment angle, AD1 is the first adaptation value, and AD2 is the second adaptation value.