Patent ID: 9243590
Filing Date: 2016-01-26
CPC Classification: F02D,F02M,Y02T

Claim Text:
1. A method of determining a correction amount of an opening degree of an EGR valve, the method determining the correction amount for correcting the opening degree to a target opening degree corresponding to a differential pressure between an exhaust pressure and an intake pressure such that an EGR rate is maintained at a predetermined target EGR rate, the EGR rate being specified on the basis of the differential pressure, the opening degree, and the air intake amount, even when the differential pressure changes, the method comprises: a differential pressure map generating step of generating a differential pressure map indicating a correlation between a rotating speed of an engine, a load factor of the engine, and the differential pressure while the opening degree is maintained at a reference opening degree, the differential pressure map being set for each of a plurality of mutually different reference opening degrees; a correction amount calculating step of calculating the correction amount equal to a difference between the target opening degree and the reference opening degree for each of mutually different combinations of the rotating speed and the load factor, by utilizing that the target opening degree is specified on the basis of the target EGR rate, the differential pressure, and the air intake amount, and that the differential pressure is specified on the basis of the rotating speed and the load factor; a basic correction amount map generating step of generating a basic correction amount map indicating a correlation between the rotating speed, the load factor, and the correction amount while the opening degree is maintained at the reference opening degree and the EGR rate is maintained at the target EGR rate, on the basis of the correction amount obtained for each of mutually different combinations of the rotating speed and the load factor; and an extended correction amount map generating step of acquiring estimated values of correction amounts not contained in the basic correction amount map, by estimating the distribution of the correction amounts not contained in the basic correction amount map, on the basis of a trend in the distribution of the correction amounts contained in the basic correction amount map, and generating an extended correction amount map indicating a correlation between the rotating speed, the load factor, and the estimated value of the correction amount, while the opening degree is maintained at the reference opening degree and the EGR rate is maintained at the target EGR rate.