FIELD

The present invention relates to a control device for an internal combustion engine.

BACKGROUND

Japanese Unexamined Patent Publication No. 2007-138837 discloses an anti-theft device of an exhaust after-treatment system installed in an exhaust pipe of an internal combustion engine. It detects cutting of electrical wiring of a temperature sensor attached to the exhaust after-treatment system so as to detect removal of the exhaust after-treatment system from the exhaust pipe.

SUMMARY

However, in the above-mentioned conventional anti-theft device of an exhaust after-treatment system, there is the problem that if the exhaust after-treatment system is removed from the exhaust pipe without cutting the electrical wiring of the temperature sensor, it is not possible to detect the removal of the exhaust after-treatment system from the exhaust pipe.

The present invention was made focusing on such a problem and has as its object to utilize a heat capacity of an exhaust after-treatment system to detect if the exhaust after-treatment system has been removed from the exhaust pipe.

To solve the above problem, the internal combustion engine according to one aspect of the present invention is provided with an engine body and an exhaust after-treatment system installed in an exhaust passage of the engine body. Further, a control device for this internal combustion engine comprises a first exhaust temperature calculation part configured to calculate a temperature of exhaust flowing into the exhaust after-treatment system as a first exhaust temperature, a second exhaust temperature calculation part configured to calculate a temperature of exhaust flowing out from the exhaust after-treatment system as a second exhaust temperature, a rate of change over time calculation part configured to calculate a rate of change over time of the first exhaust temperature and a rate of change over time of the second exhaust temperature, and a judgment part configured to judge if a state is a removed state where the exhaust after-treatment system is removed from the exhaust passage based on the difference between the rate of change over time of the first exhaust temperature and the rate of change over time of the second exhaust temperature.

According to this aspect of the present invention, it is possible to utilize a heat capacity of an exhaust after-treatment system to detect removal of an exhaust after-treatment system from an exhaust pipe.

