Exhaust temperature raising apparatus and method for internal combustion engine

Claim 2

An exhaust temperature raising apparatus for an internal combustion engine, having an exhaust throttle valve (15) that is provided in an exhaust passage (3) of the internal combustion engine and that adjusts an amount of an exhaust gas flowing in the exhaust passage (3) based on an amount of throttling of the exhaust throttle valve (15), and a fuel injection valve (12) that performs a main injection that is a fuel injection for producing an engine output and a sub-injection that is a subsidiary fuel injection after performance of the main injection, directly into a cylinder, the apparatus characterized by comprising: exhaust gas temperature increase means (4, 12, 15) for, during an engine operation during which a need to lessen an unburned fuel component contained in the exhaust gas is high, performing and controlling exhaust throttling by the exhaust throttle valve (15) and performing and controlling an exhaust gas temperature increase through combustion attributed to the main injection performed in an excess-air condition by the fuel injection valve (12) and combustion attributed to the sub-injection; exhaust gas temperature increase monitor means (16, 17) for monitoring a state of temperature increase of the exhaust gas caused by performance of the exhaust gas temperature increase means (4, 12, 15); exhaust gas temperature increase abnormality determination means (4) for determining whether there is an abnormality regarding the state of temperature increase of the exhaust gas monitored by the exhaust gas temperature increase monitor means (16, 17); and exhaust gas temperature increase stop means (4) for stopping an operation of the exhaust gas temperature increase means (4, 12, 15) when the exhaust gas temperature increase abnormality determination means (4) determines that there is an abnormality regarding the state of temperature increase of the exhaust gas.

Claim 3

An exhaust temperature raising apparatus according to claim 2, characterized in that when the exhaust gas temperature increase abnormality determination means (4) determines that there is an abnormality regarding the state of temperature increase of the exhaust gas, it is determined that the exhaust gas temperature increase means (4, 12, 15) has an abnormality, and the operation of the exhaust gas temperature increase means (4, 12, 15) is stopped.

Claim 4

An exhaust temperature raising apparatus according to any one of claims 1-3, characterized in that the exhaust gas temperature increase monitor means (16) includes an exhaust gas temperature sensor provided at a suitable location in the exhaust passage (3), and the exhaust gas temperature increase monitor means (16) monitors the state of temperature increase of the exhaust gas based on an exhaust gas temperature detected by the exhaust gas temperature sensor.

Claim 5

An exhaust temperature raising apparatus according to any one of claims 1-3, characterized in that the exhaust gas temperature increase monitor means (17) includes a back pressure sensor provided at a location in the exhaust passage upstream of a location of the exhaust throttle valve (15), and the exhaust gas temperature increase monitor means (17) monitors the state of temperature increase of the exhaust gas based on a back pressure detected by the back pressure sensor.

Claim 6

An exhaust temperature raising apparatus according to claims 1, characterized in that the exhaust gas temperature increase monitor means (16, 17) includes a back pressure sensor and an exhaust gas temperature sensor that are provided in a portion of the exhaust passage (3) upstream of the exhaust throttle valve (15), and that when a value detected by the back pressure and a value detected by the exhaust gas temperature sensor are within target ranges, respectively, the monitor means abnormality determination means (4) determines that there is no abnormality regarding the state of temperature increase of the exhaust gas.

Claim 7

An exhaust temperature raising apparatus according to any one of claims 1-6, characterized in that the exhaust gas temperature increase stop means (4) stops the operation of the exhaust gas temperature increase means (4, 12, 15) by opening the exhaust throttle valve (15) and stopping performance of the sub-injection.

Claim 8

An exhaust temperature raising apparatus according to claim 1, characterized in that the exhaust gas temperature increase monitor means (16, 17) includes at least one of a back pressure sensor and an exhaust gas temperature sensor, and that the monitor means abnormality determination means (4) determines whether the at least one of the back pressure sensor and the exhaust gas temperature sensor has an abnormality.

Claim 9

An exhaust temperature raising method for an internal combustion engine, having an exhaust throttle valve (15) that is provided in an exhaust passage (3) of the internal combustion engine and that adjusts an amount of an exhaust gas flowing in the exhaust passage (3) based on an amount of throttling by the exhaust throttle valve (15), and a fuel injection valve (12) that performs a main injection that is a fuel injection for producing an engine output and a sub-injection that is a subsidiary fuel injection after performance of the main injection, directly into a cylinder, the method characterized by comprising the steps of; during an engine operation during which a need to lessen an unburned fuel component contained in the exhaust gas is high, performing and controlling exhaust throttling by the exhaust throttle valve (15) and performing and controlling an exhaust gas temperature increase through combustion attributed to the main injection performed in an excess-air condition by the fuel injection valve (12) and combustion attributed to the sub-injection; sensing a state of temperature increase of the exhaust gas; determining whether the sensing has an abnormality; and stopping an operation of the exhaust gas temperature increasing when it is determined that the sensing has an abnormality.

Claim 10

An exhaust temperature raising method for an internal combustion engine, having an exhaust throttle valve (15) that is provided in an exhaust passage (3) of the internal combustion engine and that adjusts an amount of an exhaust gas flowing in the exhaust passage (3) based on an amount of throttling of the exhaust throttle valve (15), and a fuel injection valve (12) that performs a main injection that is a fuel injection for producing an engine output and a sub-injection that is a subsidiary fuel injection after performance of the main injection, directly into a cylinder, the method characterized by comprising the steps of; during an engine operation during which a need to lessen an unburned fuel component contained in the exhaust gas is high, performing and controlling exhaust throttling by the exhaust throttle valve (15) and performing and controlling an exhaust gas temperature increase through combustion attributed to the main injection performed in an excess-air condition by the fuel injection valve (12) and combustion attributed to the sub-injection; sensing a state of temperature increase of the exhaust gas; determining whether there is an abnormality regarding the state of temperature increase of the exhaust; and stopping an operation of the exhaust gas temperature increasing when it is determined that there is an abnormality regarding the state of temperature increase of the exhaust gas.