초록 ▼

There is provided an exhaust emission control apparatus for an internal combustion engine, which includes a failure diagnostic device that fixes three parameters selected from the group consisting of the engine speed detected by an engine speed detecting device, the fuel quantity controlled by a fue

There is provided an exhaust emission control apparatus for an internal combustion engine, which includes a failure diagnostic device that fixes three parameters selected from the group consisting of the engine speed detected by an engine speed detecting device, the fuel quantity controlled by a fuel quantity control device, the ignition timing controlled by an ignition timing control device, and the intake air volume controlled by an intake air control device at respective predetermined values, and finds values of the remaining one parameter, and compares the values of the remaining one parameter with each other to determine whether an exhaust flow control apparatus has failed or not.

대표청구항 ▼

1. An exhaust emission control apparatus for an internal combustion engine, comprising:an exhaust flow control device that suppresses exhaust flow so as to reduce harmful substances in exhaust;an engine speed detecting device that detects an engine speed;a fuel quantity control device that controls

1. An exhaust emission control apparatus for an internal combustion engine, comprising:an exhaust flow control device that suppresses exhaust flow so as to reduce harmful substances in exhaust;an engine speed detecting device that detects an engine speed;a fuel quantity control device that controls a fuel quantity contributed to output torque;an ignition timing control device that controls an ignition timing;an intake air volume control device that controls an intake air volume; anda failure diagnostic device that fixes three parameters selected from the group consisting of the engine speed detected by said engine speed detecting device, the fuel quantity controlled by said fuel quantity control device, the ignition timing controlled by said ignition timing control device, and the intake air volume controlled by said intake air volume control device at respective predetermined values and finds values of a remaining one parameter irrespective of a degree to which the exhaust flow is suppressed by said exhaust flow control device, and compares the values of the remaining one parameter with each other to determine whether said exhaust flow control device has failed.2. An exhaust emission control apparatus for an internal combustion engine according to claim 1, wherein said failure diagnostic device is operable when the exhaust flow has not been suppressed, for fixing the three parameters at respective predetermined values and finding a value of the remaining one parameter as a first parameter value in advance in a state in which an instruction for making a degree of suppression of the exhaust flow equal to a predetermined degree of suppression has been issued, and is operable when the exhaust flow is suppressed, for fixing the three parameters at the respective predetermined values, finding a value of the remaining one parameter as a second parameter value, and determining whether said exhaust flow control device has failed according to a difference between the first parameter value and the second parameter value.3. An exhaust emission control apparatus for an internal combustion engine according to claim 1, wherein said failure diagnostic device is operable when said exhaust flow control device has not failed and the exhaust flow has not been suppressed, for fixing the three parameters at respective predetermined values and finding a value of the remaining one parameter as a first parameter value in advance in a state in which an instruction for making a degree of suppression of the exhaust flow equal to a predetermined degree of suppression has been issued, and is operable when the exhaust flow is suppressed, for fixing the three parameters at the respective predetermined values, finding a value of the remaining one parameter as a second parameter value, and determining whether said exhaust flow control device has failed according to a difference between the first parameter value and the second parameter value.4. An exhaust emission control apparatus for an internal combustion engine according to claim 1, wherein said failure diagnostic device is operable when said exhaust flow control device has not failed and the exhaust flow has been suppressed, for fixing the three parameters at respective predetermined values and finding a value of the remaining one parameter as a first parameter value in advance in a state in which an instruction for making a degree of suppression of the exhaust flow equal to a predetermined degree of suppression has been issued, and is operable when the exhaust flow is not suppressed, for fixing the three parameters at the respective predetermined values, finding a value of the remaining one parameter as a second parameter value, and determining whether said exhaust flow control device has failed according to a difference between the first parameter value and the second parameter value.5. An exhaust emission control apparatus for an internal combustion engine according to claim 1, wherein said failure diagnostic device is operable when said exhaust flow control device has not failed and the exhaust flow has been suppressed, for fixing the three parameters at respective predetermined values and finding a value of the remaining one parameter as a first parameter value in advance in a state in which an instruction for making a degree of suppression of the exhaust flow equal to a predetermined degree of suppression has been issued, and is operable when the exhaust flow is suppressed, for fixing the three parameters at the respective predetermined values, finding a value of the remaining one parameter as a second parameter value and determining whether said exhaust flow control device has failed according to a difference between the first parameter value and the second parameter value.6. An exhaust emission control apparatus for an internal combustion engine according to claim 1, wherein said failure diagnostic device is operable when said exhaust flow control device has not failed and the exhaust flow has not been suppressed, for fixing the three parameters at respective predetermined values and finding a value of the remaining one parameter as a first parameter value in advance in a state in which an instruction for making a degree of suppression of the exhaust flow equal to a predetermined degree of suppression has been issued, and is operable when the exhaust flow is not suppressed, for fixing the three parameters at the respective predetermined values, finding a value of the remaining one parameter as a second parameter value and determining whether said exhaust flow control device has failed according to a difference between the first parameter value and the second parameter value.7. An exhaust emission control apparatus for an internal combustion engine according to any of claims 2 through 4, wherein said failure diagnostic device is operable when the difference between the first parameter value and the second parameter value is less than a predetermined value set according to a target degree of suppression when the exhaust flow is suppressed, for determining that said exhaust flow control device has failed.8. An exhaust emission control apparatus for an internal combustion engine according to claim 5 or 6, wherein said failure diagnostic device is operable when the difference between the first parameter value and the second parameter value is greater than a predetermined value set according to a target degree of suppression when the exhaust flow is suppressed, for determining that said exhaust flow control device has failed.9. An exhaust emission control apparatus for an internal combustion engine according to claim 1, wherein said failure diagnostic device is operable after the internal combustion engine has stopped while said exhaust flow control device is suppressing the exhaust flow, for prohibiting or reducing the suppression of the exhaust flow by said exhaust flow control device.10. An exhaust emission control apparatus for an internal combustion engine according to claim 1, further comprising an air-fuel ratio control device that controls a combustion air-fuel ratio;wherein one of the fuel quantity and the intake air volume is controlled according to the combustion air-fuel ratio.11. An exhaust emission control apparatus for an internal combustion engine according to claim 1, wherein the internal combustion engine comprises a cylinder injection type internal combustion engine that injects fuel directly into a combustion chamber, and comprises a two-stage combustion operation mode in which fuel is injected in an intake stroke or an compression stroke and additional fuel is then injected in an expansion stroke and afterward, and a compression slight-lean operation mode in which fuel is injected in the compression stroke with a combustion air-fuel ratio being set to a slightly lean air-fuel ratio;wherein said failure diagnostic device finds values of the remaining one parameter in each of said two-stage combustion operation mode and said compression slight-lean operation mode, and compares the values of the remaining one parameter with each other in each of said two-stage combustion operation mode and said compression slight-lean operation mode.