Exhaust gas cleaning apparatus having particulate collector for use in automotive vehicle

Abstract

An exhaust gas cleaning apparatus of the present invention is advantageously used in a diesel engine. A collector for collecting particulates contained in the exhaust gas is disposed in an exhaust pipe of the engine. Damages in the collector are detected based on a pressure difference between an inlet and an outlet of the collector. In order to correctly detect the damages based on the pressure difference, an exhaust gas volume flowing through the collector is increased to a target volume by raising exhaust gas temperature. The exhaust gas temperature is raised by injecting fuel into the engine at a timing when an engine output is not increased by such fuel injection. The pressure difference, based on which the damages in the collector are detected, is measured after the exhaust gas volume reached the target volume. It is determined that the damages in the collector have occurred if the pressure difference is lower than a predetermined value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an entire system for cleaning exhaust gas from an internal combustion engine;

FIG. 2A is a graph showing a relation between an amount of exhaust gas and a pressure difference between an upstream end and a downstream end of a particulate collector.

FIG. 2B shows formula (1) for calculating a target flow amount of exhaust gas and formula (2) for calculating a temperature rise required for increasing a flow amount to the target flow amount;

FIG. 3 is a flowchart showing a process of detecting damages in a particulate collector;

FIG. 4 is a graph showing a relation between a temperature rise in the exhaust gas and an amount of post injection; and

FIG. 5 are time charts showing the process of detecting damages in the particulate collector.

Claims

1. An exhaust gas cleaning apparatus for an internal combustion engine, comprising: a collector for collecting particulates contained in exhaust gas of the internal combustion engine;a pressure sensor for detecting a pressure difference between an inlet and an outlet of the collector; andmeans for detecting damages in the collector based on the pressure difference detected by the pressure sensor, wherein:the detecting means includes means for determining whether an exhaust gas volume passing through the collector is lower than a target volume and means for increasing the exhaust gas volume if the exhaust gas volume is lower than the target volume.

2. The exhaust gas cleaning apparatus as in claim 1, wherein: the increasing means increases temperature of the exhaust gas.

3. The exhaust gas cleaning apparatus as in claim 2, wherein: the increasing means supplies fuel to the internal combustion engine to increase the temperature of the exhaust gas under a condition not to increase an output of the internal combustion engine.

4. The exhaust gas cleaning apparatus as in claim 3, further including means for controlling an amount of fuel to be supplied by the increasing means, wherein: the controlling means calculates a temperature rise in the exhaust gas that is necessary for increasing the exhaust gas volume to the target volume and calculates an amount of fuel that is necessary for realizing the calculated temperature rise in the exhaust gas.

5. The exhaust gas cleaning apparatus as in claim 4, wherein: the increasing means supplies the fuel to the internal combustion engine for raising the temperature of the exhaust gas only when the temperature of the exhaust gas that is expected to be realized by supplying the amount of fuel calculated by the controlling means is lower than a predetermined temperature limit.

6. The exhaust gas cleaning apparatus as in claim 5, wherein: a catalyst for promoting exhaust gas cleaning is disposed in the collector, and the predetermined temperature limit is a temperature, at a higher temperature than which the catalyst deteriorates.

7. A process of detecting damages of a collector for collecting particulates included in exhaust gas of an internal combustion engine, the process comprising: checking whether the engine is stably operating;calculating a present exhaust gas volume if the engine is stably operating;determining whether the present exhaust gas volume is smaller than a target volume that is necessary for detecting the damages of the collector;calculating, if the present exhaust gas volume is smaller than the target volume, a temperature rise in the exhaust gas that is necessary to increase the present exhaust gas volume to the target volume;supplying fuel to the engine under a condition not to increase an output of the engine, so that the temperature rise that is necessary to increase the exhaust gas volume to the target volume is realized;detecting a pressure difference between an inlet and an outlet of the collector after the exhaust gas volume reaches the target volume; anddetermining that the collector is damaged if the pressure difference is smaller than a predetermined value.