Patent ID: 8447492

Claim:
An engine characteristic estimation method for estimating steady state values of a specific engine characteristic, which correspond to respective values of a specific engine control parameter in a specific engine operating state, comprising: setting an amount of change in the specific engine characteristic for each of different predetermined times from when the specific engine control parameter is changed at the specific engine operating state, wherein the amount of change is set as a product of a change value and a dimensionless known value, and wherein the change value is a change amount in a post-change steady state value of the specific engine characteristic after a change of the specific engine control parameter as compared with a pre-change steady state value before the change in the engine control parameter, and further wherein the dimensionless known value is a value at each of the predetermined times for said specific engine operating state; calculating a value of the specific engine characteristic at a particular time as a sum of the products of each change of the specific engine control parameter before the particular time, wherein, for each change in the specific engine control parameter, the specific engine characteristic changes by the change amount between the pre-change steady state value and the post-change steady state value corresponding to the change amount resulting after a time has elapsed since the specific engine control parameter is changed, each time the specific engine control parameter is changed before the particular time; and performing a conformance test, in which the specific engine control parameter is changed in a stepwise manner at the specific engine operating state, and obtaining measured values of the specific engine characteristic for multiple times, and calculating change values based on the measured values and sums of products calculated for times corresponding to the multiple times, and then estimating the steady state values of the specific engine characteristic for the respective values of the specific engine control parameter using the calculated change values.