Control device for internal combustion engine

Abstract

A control device for an internal combustion engine is mounted on a vehicle, and includes an engine, a catalyst and a control unit. The engine is a bifuel engine using gas fuel and liquid fuel as its fuel source. The control unit makes an air fuel ratio rich and increases a proportion of the gas fuel if a temperature of the catalyst is higher than a predetermined upper limit value at a time when the liquid fuel is used.

Description

technical field [0001] The present invention relates to vehicle control including an internal combustion engine (engine). Background technique [0002] Conventionally, when the temperature of the catalyst becomes high, the technique of reducing the exhaust gas temperature by increasing the fuel injection amount is known. For example, Patent Document 1 discloses a technique of increasing the proportion of ethanol fuel when the temperature of the catalyst rises above the upper limit temperature for fuel containing ethanol. In this case, since the heat of evaporation and the combustion temperature are different, the temperature of the catalyst is reduced and the deterioration of the catalyst is suppressed. In addition, Patent Document 2 discloses a technique of changing the setting of the temperature at which fuel cut is performed based on the oxygen-containing fuel ratio of the fuel in order to prevent an excessive temperature rise in the exhaust system. [0003] Patent Docu...

AI Technical Summary

Problems solved by technology

Therefore, when the fuel cut is performed with deceleration thereafter, the above-mentioned unburned fuel flows into the exhaust system, and since the unburned fuel and a large amount of oxygen promote the oxidation reaction in the catalyst, there is a possibility that the temperature of the catalyst is raised and the catalyst is further deteriorated.

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