CONTROLLER FOR INTERNAL COMBUSTION ENGINE

摘要

An automatically stoppable internal combustion engine comprises an exhaust purification catalyst, an upstream side air-fuel ratio sensor, a downstream side air-fuel ratio sensor, and sensor heaters heating air-fuel ratio sensors. A controller comprises an air-fuel ratio control part and a heating control part. The heating control part controls the temperature of the upstream side air-fuel ratio sensor to the activation temperature or more and the temperature of the downstream side air-fuel ratio sensor to less than the activation temperature during automatic stop of the internal combustion engine. The air-fuel ratio control part controls the air-fuel ratio of the exhaust gas based on the outputs of the two air-fuel ratio sensors during engine operation and controls the air-fuel ratio of the exhaust gas temporarily based on the output of the upstream side air-fuel ratio sensor without using the output of the downstream side air-fuel ratio sensor.

主权项

1. A controller for an internal combustion engine which has automatic stop function equipped with:
an exhaust purification catalyst provided in an exhaust passage; an upstream side air-fuel ratio sensor provided in the exhaust passage at an upstream side of the exhaust purification catalyst in the direction of flow of exhaust; a downstream side air-fuel ratio sensor provided in the exhaust passage at a downstream side of the exhaust purification catalyst in the direction of flow of exhaust; an upstream side sensor heater heating the upstream side air-fuel ratio sensor; and a downstream side sensor heater heating the downstream side air-fuel ratio sensor, comprising: an air-fuel ratio control part configured to control an air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst; and a heating control part configured to control heating of the upstream side air-fuel ratio sensor by the upstream side sensor heater and heating of the downstream air-fuel sensor by the downstream side sensor heater, wherein the heating control part is further configured to control the upstream side sensor heater and the downstream side sensor heater so that the temperature of the upstream side air-fuel ratio sensor reaches the activation temperature or more and so that the temperature of the downstream side air-fuel ratio sensor reaches less than the activation temperature during automatic stop of the internal combustion engine, and the air-fuel ratio control part is further configured to: control the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst based on an output of the upstream side air-fuel ratio sensor and an output of the downstream side air-fuel ratio sensor during engine operation; and control the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst temporarily based on the output of the upstream side air-fuel ratio sensor without using the output of the downstream side air-fuel ratio sensor even during engine operation when the internal combustion engine is restarted after automatic stop.