Exhaust gas purification apparatus

Abstract

An exhaust gas purification device where occurrence of detection failure of injection nozzle clogging is suppressed. An exhaust gas purification device for an engine, having a reduction catalyst (4) provided in the exhaust system of the engine (1) and reducing and purifying a nitrogen oxide in exhaust gas by a urea water, a urea water tank (6) storing the urea water, a urea water supply means (7) for sucking up the urea water and sending it out after mixing it with high-pressure air, and an injection nozzle (5) for injecting the urea water, mixed with the high-pressure air, inside an exhaust pipe (3) of the exhaust gas system, to the exhaust gas upstream side of the reduction catalyst (4). The exhaust gas purification device further has a clogging detection means (8) for detecting clogging of the injection nozzle based on a detection output on the pressure of air introduced into the urea water supply means (7) and a detection output on the temperature of the injection nozzle (5).

Description

technical field [0001] The present invention relates to an exhaust purification device for an engine, which injects a reducing agent mixed with high-pressure air to the upstream side of the exhaust gas of a reduction catalyst through a nozzle, thereby reducing the emission from a diesel engine mounted on a mobile vehicle. Nitrogen oxides (NOx) emitted from gasoline engines, etc. x ) to remove it. Specifically, it relates to an exhaust purification device that detects clogging of nozzles based on the pressure of the high-pressure air and the temperature of the nozzles, thereby suppressing erroneous detection of the clogging. Background technique [0002] As the removal of harmful substances in the exhaust gas discharged from the engine, especially the removal of NO x To purify exhaust gas systems, several exhaust gas purification devices have been proposed. One of the exhaust purification devices places a reduction catalyst in the engine exhaust system, injects and supplie...

AI Technical Summary

Problems solved by technology

[0003] In such an exhaust purification device, when injecting the reducing agent, the nozzle may be clogged due to precipitation of the reducing agent, for example, urea precipitation, so that the reducing agent cannot be sufficiently injected into the exhaust passage.

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