Device for controlling the rise of the catalyst temperature in an internal combustion engine

Abstract

A device for controlling the rise of the catalyst temperature in an internal combustion engine, capable of quickly raising the catalyst temperature at the start to satisfy the exhaust gas regulations to a sufficient degree. The device comprises a means for picking up data corresponding to the temperature of the catalyst provided in the exhaust pipe of the internal combustion engine as catalyst temperature TC, a variety of sensors for detecting the operation conditions of the internal combustion engine, a means for controlling the air-to-fuel ratio of the internal combustion engine depending upon the operation conditions, and an air-to-fuel ratio lean-correction means S which, when the catalyst temperature is lower than a predetermined temperature corresponding to an activating temperature of the catalyst, corrects a target air-to-fuel ratio A/Fo toward the lean side to promote the activation of the catalyst, wherein the variety of sensors detect at least intake-air-amount data and crank angle data, and, when the temperature of the catalyst is lower than the predetermined temperature, the air-to-fuel ratio lean-correction means sets the target air-to-fuel ratio to a lean activating air-to-fuel ratio which is larger than an air-to-fuel ratio A/Fn of during the normally controlled operation and is higher than a stoichiometric air-to-fuel ratio.