EXHAUST EMISSION CONTROL METHOD FOR ENGINE

PROBLEM TO BE SOLVED: To provide an exhaust emission control method for an engine that can exhibit exhaust purification performance at a constant level by controlling the engine even when a chemical heat storage device cannot be operated.SOLUTION: An exhaust emission control method for an engine includes the steps of: determining whether or not warming of an oxidation catalyst is necessary; and determining whether or not an operation of a chemical heat storage device is possible. When a determination that the warming of the oxidation catalyst is necessary is made and a determination that the operation of the chemical heat storage device is possible is made, the chemical heat storage device is operated to warm the oxidation catalyst. When a determination that the warming of the oxidation catalyst is necessary is made and a determination that the operation of the chemical heat storage device is impossible is made, control of the engine is switched to exhaust priority control to reduce discharge of air pollutants in exhaust gas to outside air.SELECTED DRAWING: Figure 3 【課題】化学蓄熱装置が稼働できない場合であっても、エンジン制御によって一定の排気浄化性能を発揮することができるエンジンの排気浄化制御方法を提供すること。【解決手段】エンジンの排気浄化制御方法は、酸化触媒の暖機が必要か否かを判定するステップと、化学蓄熱装置の稼働可否を判定するステップと、を備える。そして、酸化触媒の暖機が必要と判定され、かつ化学蓄熱装置が稼働可と判定された場合は酸化触媒を暖機するように化学蓄熱装置を動作させる。一方、酸化触媒の暖機が必要と判定され、かつ化学蓄熱装置が稼働不可と判定された場合はエンジンの制御を排気優先制御に切り替えて排気ガス中の大気汚染物質の外気への排出を低減する。【選択図】図３