Excess air rate detecting apparatus and an excess air rate control apparatus for an engine

摘要

An excess air rate detecting apparatus and a control apparatus using the same are provided. In accordance with operating conditions of an engine (1) which includes an exhaust gas recirculation system, the detecting apparatus repeatedly detects the excess air rate of an air-fuel mixture supplied to the engine while exhaust gas is being circulated. The intake pressure of the engine is detected, the quantity of recirculation of the exhaust gas is estimated in accordance with at least the detected intake pressure, an equivalent intake air quantity of the engine is estimated by equivalent intake air quantity estimating means, and the excess air rate for the engine is estimated in accordance with the fuel supply quantity and the estimated equivalent intake air quantity. The estimated excess air rate is stored in storage means, the quantity of recirculation of the exhaust gas is estimated by the equivalent intake air quantity estimating means in accordance with at least the estimated exhaust gas recirculation quantity and the excess air rate stored in the storage means and estimated for the last cycle but a predetermined number of cycles, and the fuel supply quantity and/or exhaust gas recirculation quantity is adjusted by means of the estimated excess air rate to control the excess air rate for a target value.