Diagnostic device for exhaust gas aftertreatment device, diagnostic method for exhaust gas aftertreatment device, and diagnostic program for exhaust gas aftertreatment device

A diagnostic device for an exhaust gas aftertreatment device that has a filter for collecting fine particles from exhaust gas of an engine and is provided in a vehicle, the diagnostic device diagnosing a malfunction in the exhaust gas aftertreatment device, the diagnostic device comprising:

• a temperature detection device that detects a filter inlet-side temperature and a filter outlet-side temperature;
• a differential pressure detection device that detects a differential pressure between a filter inlet-side pressure and a filter outlet-side pressure;
• an intake air pressure detection device that detects an intake air pressure of the engine;
• and
• a controller that determines the malfunction in the exhaust gas aftertreatment device based on values detected by the temperature detection device, the differential pressure detection device, and the intake air pressure detection device,
• wherein the vehicle is a work machine, and the work machine includes
• a plurality of movable portions, and
• a power source that supplies power to the plurality of movable portions, and
• wherein the controller performs control for limiting an output from the power source within a predetermined range in a case where the controller determines that the exhaust gas aftertreatment device has malfunctioned,
• wherein the diagnostic device further comprises an operation device that outputs operation commands for operating the movable portions,
• wherein the controller calculates an accumulated time during which the operation device outputs the operation commands in a state where the output from the power source is limited.

A diagnostic method for an exhaust gas aftertreatment device that has a filter for collecting fine particles from exhaust gas of an engine and is provided in a vehicle, the diagnostic method for diagnosing a malfunction in the exhaust gas aftertreatment device, the diagnostic method comprising:

• a temperature detection step of detecting a filter inlet-side temperature and a filter outlet-side temperature;
• a differential pressure detection step of detecting a differential pressure between a filter inlet-side pressure and a filter outlet-side pressure;
• an intake air pressure detection step of detecting an intake air pressure of the engine;
• and
• a determination step, which is executed by a controller, of determining the malfunction in the exhaust gas aftertreatment device based on values detected in the temperature detection step, the differential pressure detection step, and the intake air pressure detection step,
• wherein the controller determines the malfunction in the exhaust gas aftertreatment device based on an index, and
• wherein the index is a value based on a ratio between the filter inlet-side temperature and the filter outlet-side temperature and a ratio between the differential pressure and the intake air pressure of the engine.