Patent ID: 7264642

Claim:
An exhaust gas cleaning apparatus comprising: a filter for trapping particulates contained in exhaust gas of an internal combustion engine; a differential pressure detection means that detects a differential pressure between a filter inlet end and a filter outlet end, said differential pressure detection means being configured to control regeneration of the filter in response to the differential pressure between the filter inlet end and the filter outlet end; differential detection means for detection of a temperature differential between the filter inlet end and the filter outlet end; determination means for determining regeneration completion timing of the filter in response to the temperature differential detection means; and estimation means for estimating the quantity of residual ash in the filter based on an output of the differential pressure detection means in response to the determination of the regeneration completion timing of the filter by the determination means, wherein the determination means includes means of determining whether or not regeneration of the filter has been completed by comparing the temperature differential with a prescribed non-zero value.