FAILURE DETERMINATION APPARATUS FOR OXYGEN CONCENTRATION SENSOR

摘要

A failure determination apparatus for an oxygen concentration sensor disposed downstream of a catalyst provided in an exhaust system of an internal combustion engines is provided for detecting a failure in the oxygen concentration sensor with high accuracy while preventing an erroneous determination of the failure. The failure determination apparatus comprises: a failure determination device for determining a failure in the oxygen concentration sensor based on the length of a period when the output of the oxygen concentration sensor passes through a predetermined output section during enrichment control after a fuel cut mode of the internal combustion engine is released, or based on the length of a period until the output of the oxygen concentration sensor during the enrichment control after release of the fuel cut mode reaches a predetermined output; a rich fuel supply amount calculation device for calculating the time average of an enriching fuel supply amount, relative to a fuel supply amount necessary for stoichiometric combustion, based on an actual fuel supply amount during the enrichment control; and a failure determination restriction device for restricting failure determination of the failure determination device based on the time average of the enriching fuel supply amount.

主权项

1. A failure determination apparatus for an oxygen concentration sensor disposed downstream of a catalyst provided in an exhaust system of an internal combustion engine, comprising:
a failure determination device for determining a failure in the oxygen, concentration sensor based on a length of a period when an output of the oxygen concentration sensor passes through a predetermined output section during enrichment control of an exhaust air-fuel ratio which is performed after a fuel cut mode of the internal combustion engine is released, or based on a length of a period until the output of the oxygen concentration sensor during the enrichment control after release of the fuel cut mode reaches a predetermined output; a rich fuel supply amount calculation device for calculating a time average of an enriching fuel supply amount, which is necessary for enrichment of the exhaust air-fuel ratio, relative to a fuel supply amount necessary for stoichiometric combustion of the internal combustion engine, based on an actual fuel supply amount during the enrichment control; and a failure determination restriction device for restricting failure determination of the failure determination device based on the time average of the enriching fuel supply amount.