Control apparatus and method for internal combustion engine

Claim 1

A control apparatus for an internal combustion engine, comprising: a) secondary air supplying means, having an air pump, for operatively supplying a secondary air into a portion of an exhaust passage of the engine located upstream with respect to a three-way catalytic converter interposed in the exhaust passage; b) engine driving condition detecting means for detecting an engine driving condition, said engine driving condition detecting means including an engine idling sensor which is so constructed and arranged as to detect whether the engine enters an engine idling state, an airflow meter which is so constructed and arranged as to detect an intake air quantity supplied to the engine, and an air-fuel mixture ratio sensor which is so constructed and arranged in the portion of the exhaust passage located upstream with respect to the catalytic converter as to detect an air-fuel mixture ratio of the engine; c) a control unit which is so constructed and arranged as to determine whether the engine falls in the idling state and determine whether the secondary air is supplied by said secondary air supplying means to the portion of the exhaust passage of the engine located upstream with respect to the catalytic converter, as to determine a basic fuel supply quantity on the basis of the detected engine driving condition and a supplied quantity of the secondary air, as to estimate an excess coefficient at an inlet portion of the catalytic converter on the basis of the detected air/fuel mixture ratio and the supplied quantity of the secondary air when determining that the engine falls in the idling state and that the secondary air is supplied into the portion of the exhaust passage located upstream with respect to the catalytic converter, as to determine an incremental correction quantity percentage of fuel supplied to the engine for the basic fuel supply quantity so that the excess coefficient gives a predetermined value, and as to determine a retardation correction quantity of an ignition timing for a basic ignition advance angle value according to the determined incremental correction percentage; d) fuel supplying means for supplying a final fuel supply quantity determined according to the basic fuel supply quantity and the incremental correction quantity percentage to the engine derived by said control unit; and e) an ignition device which is so constructed and arranged as to ignite the fuel supplied to the engine at the basic ignition timing advance angle value which is retarded by the retardation correction quantity determined by said control unit.

Claim 16

A method for controlling a fuel supply quantity and an ignition timing of an internal combustion engine, said engine being provided with a) secondary air supplying means, having an air pump, for operatively supplying a secondary air into a portion of an exhaust passage of the engine located upstream with respect to a three-way catalytic converter interposed in the exhaust passage; and b) engine driving condition detecting means for detecting an engine driving condition, said engine driving condition detecting means including an engine idling sensor which is so constructed and arranged as to detect whether the engine enters an engine idling state, an airflow meter which is so constructed and arranged as to detect an intake air quantity supplied to the engine, and an air-fuel mixture ratio sensor which is so constructed and arranged in the portion of the exhaust passage located upstream with respect to the catalytic converter as to detect an air-fuel mixture ratio of the engine, said method comprising the steps of; c) determining whether the engine falls in the idling state and whether the secondary air is supplied by said secondary air supplying means to the portion of the exhaust passage of the engine located upstream with respect to the catalytic converter; d) determining a basic fuel supply quantity on the basis of the detected engine driving condition and a quantity of the secondary air; e) estimating an excess coefficient at an inlet portion of the catalytic converter on the basis of the detected air/fuel mixture ratio and a supplied quantity of the secondary air when determining that the engine falls in the idling state and that the secondary air is supplied into the portion of the exhaust passage located upstream with respect to the catalytic converter; f) determining an incremental correction quantity percentage of fuel supplied to the engine for the basic fuel supply quantity so that the excess coefficient gives a predetermined value; and g) determining a retardation correction quantity of an ignition timing for a basic ignition advance angle value according to the determined incremental correction percentage.

Claim 17

A method for controlling a fuel supply quantity and an ignition timing of an internal combustion engine, said engine being provided with a) secondary air supplying means, having an air pump, for operatively supplying a secondary air into a portion of an exhaust passage of the engine located upstream with respect to a three-way catalytic converter interposed in the exhaust passage; and b) engine driving condition detecting means for detecting an engine driving condition, said engine driving condition detecting means including an engine idling sensor which is so constructed and arranged as to detect whether the engine enters an engine idling state, an airflow meter which is so constructed and arranged as to detect an intake air quantity supplied to the engine, and an air-fuel mixture ratio sensor which is so constructed and arranged in the portion of the exhaust passage located upstream with respect to the catalytic converter as to detect an air-fuel mixture ratio of the engine, said method comprising the steps of; c) determining whether the engine falls in the idling state and whether the secondary air is supplied by said secondary air supplying means to the portion of the exhaust passage of the engine located upstream with respect to the catalytic converter; d) determining a basic fuel supply quantity on the basis of the detected engine driving condition and a quantity of the secondary air; e) estimating an excess coefficient at an inlet portion of the catalytic converter on the basis of the detected air/fuel mixture ratio and a supplied quantity of the secondary air when determining that the engine falls in the idling state and that the secondary air is supplied into the portion of the exhaust passage located upstream with respect to the catalytic converter; f) determining an incremental correction quantity percentage of fuel supplied to the engine for the basic fuel supply quantity so that the excess coefficient gives a predetermined value; and g) determining a retardation correction quantity of an ignition timing for a basic ignition advance angle value according to the determined incremental correction percentage.