DIAGNOSTIC DEVICE

摘要

A diagnostic device for an exhaust gas purification system that has a diesel oxidation catalyst (DOC), a diesel particulate filter, and an exhaust pipe injection device. The device includes a sensor for detecting a temperature of the DOC, a first calculation unit for converting an integration time of the detected temperature between regeneration intervals into a thermal history time with respect to a predetermined set temperature, and calculating a degree of degradation of the DOC based on this thermal history time, a second calculation unit for calculating a quantity of heat generated in the DOC based on the detected temperature during a forced regeneration execution period, and calculating another degree of degradation of the DOC based on the quantity of heat generated; and a diagnosis unit for diagnosing a degradation state of the DOC based on the degrees of degradation entered from the first and second calculation units.

主权项

1. A diagnostic device for use with an exhaust purification system including an oxidation catalyst arranged to oxidize hydrocarbons contained in exhaust gas, a filter arranged downstream of the oxidation catalyst with respect to an gas exhaust flowing direction and configured to collect particulate matter contained in the exhaust gas, and forced regeneration unit configured to perform a forced regeneration of supplying the hydrocarbons to the oxidation catalyst and burning and removing particulate matter accumulated in the filter, the diagnostic device comprising:
a first temperature sensor to detect a temperature of the oxidation catalyst; a first degradation degree calculation unit configured to convert a cumulative time of the temperature entered from the first temperature sensor to a thermal history time for a specified set temperature in a period from an end of a forced regeneration to a start of a next forced regeneration, and calculate a first degradation degree of the oxidation catalyst based on the thermal history time; a second degradation degree calculation unit configured to calculate a first quantity of heat generated in the oxidation catalyst based on the temperature entered from the first temperature sensor in a forced regeneration period, and calculate a second degradation degree of the oxidation catalyst based on the first quantity of heat generated; and a first diagnosis unit configured to perform a diagnosis as to degradation of the oxidation catalyst based on at least one of the first degradation degree entered from the first degradation degree calculation unit and the second degradation degree entered from the second degradation degree calculation unit.