Apparatus and method for preventing overheating of exhaust purification filter

Abstract

An apparatus for preventing a filter for purifying exhaust gas emitted by a vehicle diesel engine from overheating is provided. The filter filters particulate matter in exhaust gas. Particulate matter that is accumulated in the filter through filtering is burned and purified by executing a temperature increase process in which the filter is heated. The apparatus includes an electronic control unit as overheat prevention means. During the temperature increase process, the overheat prevention means executes an increase process for increasing the flow rate of exhaust gas when the filter is likely to overheat. As a result, the filter is effectively prevented from overheating.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to an apparatus and a method for preventing overheating of an exhaust purification filter that is provided in the exhaust system of an internal combustion engine, which exhaust purification filter filters particulate matter in exhaust gas, and burns and purifies particulate matter accumulated during the filtering. [0002] Japanese Laid-Open Patent Publication No. 2002-371889 discloses a technique for purifying exhaust gas, in which a NOx storage reduction catalyst is disposed in the exhaust system of an internal combustion engine. In the configuration of the publication, exhaust gas is set to reducing atmosphere when the internal combustion engine is decelerating, so that NOx stored in a catalyst is reduced. When setting exhaust gas to reducing atmosphere, the intake flow rate is reduced or the amount of exhaust gas recirculation is increased. [0003] Instead of or in addition to the catalyst, an exhaust purification fil...

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Benefits of technology

[0007] Accordingly, it is an objective of the present invention to provide an apparatus that effectively prevent an exhaust purification filter of an internal combustion engine from overheating.

[0009] The present invention also provides an apparatus for preventing a filter for purifying exhaust gas emitted by an internal combustion engine from overheating. The filter filters particulate matter in exhaust gas. Particulate matter that is accumulated in the filter through filtering is burned and purified by executing a temperature increase process in which the filter is heated. The apparatus includes means for reducing the rate of decrease of the flow rate of exhaust gas when the filter is likely to overheat during the temperature increase process.

[0010] Another objective of the present invention is to provide a method that effectively prevents an exhaust purification filter of an internal combustion engine from overheating.

[0011] Accordingly, the present invention provides a method for preventing a filter for purifying exhaust gas emitted by an internal combustion engine from overheating. The method includes: filtering particulate matter in exhaust gas with the filter; burning and purifying particulate matter that is accumulated in the filter through filtering by executing the temperature increase process in which the filter is heated; and executing an increase process for increasing the flow rate of exhaust gas when the filter is likely to overheat during the temperature increase process.

Problems solved by technology

Some of the heat generated during the regeneration of the exhaust purification filter is lost to the outside.

Thus, if the internal combustion engine is decelerated during the temperature increase process for regenerating the filter, heat is accumulated in the filter, causing the filter to overheat or deteriorate.

Thus, an exhaust purification filter becomes more likely to overheat.

However, even if this is the case, since oxygen exists in the filter in one form or another, it is difficult stop the generation of the heat right away.

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