US 2006/0123768 A1 · Catalytic converter degradation

Abstract

A catalytic converter degradation determining system is configured to accurately determine if a NOx trapping catalytic converter is degraded. The system is configured to detect or estimate the temperature of a NOx trapping catalytic converter and sets a pre-degradation adsorption efficiency and a post-degradation adsorption efficiency based on the catalytic converter temperature. The system then multiplies the adsorption efficiencies by an exhaust gas NOx quantity to calculate trapped NOx rates. The individual trapping NOx rates are summed over a prescribed amount of time to estimate the pre-degradation and post-degradation NOx trapping amounts. After the prescribed amount of time elapses, the system compares the pre-degradation NOx trapping amount to the post-degradation NOx trapping amount and determines if the difference between the two is smaller than a prescribed value. If the difference is smaller than the prescribed value, then the system determines that the catalytic converter is degraded.

Claims19

Dependent claims

A catalytic converter degradation determining system comprising:

a heat of reaction detecting section configured to detect a heat of reaction of an oxidation induced by a catalytic converter having at least an oxidizing function;
and
a degradation determining section configured to determine if the catalytic converter is degraded based on a decrease in the heat of reaction.

A catalytic converter degradation determining system comprising:

a temperature detecting section configured to detect a temperature of a catalytic converter that traps NOx in exhaust gas when a lean air-fuel mixture is used for combustion and that cleans and releases trapped NOx when a stoichiometric air-fuel mixture or a rich air-fuel mixture is used for combustion;
a pre-degradation NOx adsorption efficiency establishing section configured to establish a pre-degradation NOx adsorption efficiency of the catalytic converter corresponding to conditions under which the catalytic converter is new based on the temperature of the catalytic converter;
a pre-degradation trapped NOx estimating section configured to estimate a pre-degradation NOx trapping amount using the pre-degradation NOx adsorption efficiency;
a post-degradation NOx adsorption efficiency establishing section configured to establish a post-degradation NOx adsorption efficiency of the catalytic converter corresponding to conditions under which the catalytic converter is degraded based on the temperature of the catalytic converter;
a post-degradation trapped NOx estimating section configured to estimate a post-degradation NOx trapping amount using the post-degradation NOx adsorption efficiency;
and
a degradation determining section configured to determine that the catalytic converter is degraded when a difference between the pre-degradation NOx trapping amount and the post-degradation NOx trapping amount is below a prescribed value.

4 more elements

Dependencies are inferred from the claim text.

Catalytic converter degradation

Life of this patent

Catalytic converter degradation

Life of this patent

Abstract

Claims19