초록 ▼

An exhaust passage (2) of a diesel engine (1) is provided with a filter (41) for trapping particulate matter. Regeneration of the filter (41) is divided into first to third phases. In the first phase the filter temperature is raised to the combustion temperature of the particulate matter in a short

An exhaust passage (2) of a diesel engine (1) is provided with a filter (41) for trapping particulate matter. Regeneration of the filter (41) is divided into first to third phases. In the first phase the filter temperature is raised to the combustion temperature of the particulate matter in a short period of time through control of the exhaust gas temperature. In the second phase, the oxygen concentration of the exhaust gas is held at a predetermined low level while the filter temperature is maintained so as to prevent excessive combustion of particulate matter. In the third phase, wherein the amount of trapped particulate matter has been reduced, the oxygen concentration of the exhaust gas is held at a predetermined high level while the filter temperature is maintained so as to complete the combustion of the trapped particulate matter.

대표청구항 ▼

1. A regeneration device for a filter which traps particulate matter contained in the exhaust gas of an internal combustion engine, the particulate matter burning at a predetermined temperature, the device comprising:an exhaust gas temperature adjustment mechanism which regulates a temperature of th

1. A regeneration device for a filter which traps particulate matter contained in the exhaust gas of an internal combustion engine, the particulate matter burning at a predetermined temperature, the device comprising:an exhaust gas temperature adjustment mechanism which regulates a temperature of the exhaust gas; an exhaust gas oxygen concentration adjustment mechanism which regulates an oxygen concentration of the exhaust gas; a sensor which detects a temperature of the filter; and a controller functioning to: control the exhaust gas temperature adjustment mechanism in a first phase such that the exhaust gas temperature is raised until the temperature of the filter rises to a predetermined temperature; control the exhaust gas oxygen concentration adjustment mechanism in a second phase following the first phase to cause the oxygen concentration of the exhaust gas to be held at a first target concentration while controlling the exhaust gas temperature adjustment mechanism to cause the temperature of the filter to be maintained at the predetermined temperature; and control the exhaust gas oxygen concentration adjustment mechanism in a third phase following the second phase to cause the oxygen concentration of the exhaust gas to be held at a second target concentration which is higher than the first target concentration while controlling the exhaust gas temperature adjustment mechanism to cause the temperature of the filter to be maintained at the predetermined temperature. 2. The regeneration device as defined in claim 1, wherein the controller further functions to set the duration of the first phase to be shorter as the filter temperature at the start of the first phase increases.3. The regeneration device as defined in claim 1, wherein the regeneration device further comprises a sensor which detects an amount of trapped particulate matter in the filter, and the controller further functions to set the duration of the first phase to be longer as the amount of trapped particulate matter in the filter at the start of the first phase increases.4. The regeneration device as defined in claim 1, wherein the controller further functions to set the duration of the first phase to zero when the amount of trapped particulate matter in the filter at the start of the first phase does not reach a predetermined amount.5. The regeneration device as defined in claim 4, wherein the predetermined amount is set on the basis of an amount of trapped particulate matter at the start of the second phase which is sufficient such that the temperature of the filter is not caused to exceed a maximum allowable temperature when the trapped particulate matter burns during the second phase.6. The regeneration device as defined in claim 1, wherein the controller further functions to set a target temperature for the exhaust gas temperature at an inlet of the filter in the first phase to a higher temperature than the predetermined temperature, and to control the exhaust gas temperature adjustment mechanism on the basis of the target temperature.7. The regeneration device as defined in claim 6, wherein the controller further functions to gradually decrease the target temperature for the exhaust gas temperature at the inlet of the filter in the first phase toward the predetermined temperature after setting the target temperature to a higher temperature than the predetermined temperature.8. The regeneration device as defined in claim 1, wherein the exhaust gas temperature adjustment mechanism comprises a fuel injection nozzle which injects fuel for combustion into the internal combustion engine, and the controller further functions to raise the exhaust gas temperature by retarding a fuel injection timing of the fuel injection nozzle.9. The regeneration device as defined in claim 1, wherein the exhaust gas temperature adjustment mechanism comprises a fuel injection nozzle which injects fuel for combustion into the internal combustion engine through a main injection, and the controller further functions to raise the exhaust gas temperature by causing the fuel injector to perform a post injection following the main injection.10. The regeneration device as defined in claim 1, wherein the exhaust gas temperature adjustment mechanism comprises a fuel injection nozzle which injects fuel for combustion into the internal combustion engine through a main injection and an intake throttle which regulates an intake fresh air amount of the internal combustion engine, and the controller further functions to raise the exhaust gas temperature by causing the fuel injection nozzle to perform a post injection following the main injection while causing the intake throttle to increase the intake fresh air amount.11. The regeneration device as defined in claim 1, wherein the filter is provided on an exhaust passage of the internal combustion engine, the exhaust gas temperature adjustment mechanism comprises a turbocharger which boosts a charge amount of an intake fresh air of the internal combustion engine using an exhaust gas pressure in the exhaust passage, the turbocharger performing pressure charging in accordance with the rotation of a turbine which is provided in the exhaust passage upstream of the filter and operated by exhaust gas pressure, the turbine comprising a variable nozzle for adjusting a workload thereof, and the controller further functions to raise the exhaust gas temperature by causing the variable nozzle to reduce the workload of the turbine.12. The regeneration device as defined in claim 1, wherein the exhaust gas temperature adjustment mechanism comprises a common rail type fuel injection device which supplies fuel for combustion to the internal combustion engine under a predetermined pressure, and the controller further functions to raise the exhaust gas temperature by causing the common rail type fuel injection device to reduce the fuel supply pressure.13. The regeneration device as defined in claim 1, wherein the controller, further functions, in the second phase, to control the exhaust gas oxygen concentration adjustment mechanism to cause the oxygen concentration of the exhaust gas to gradually increase toward the second target concentration, after controlling the exhaust gas oxygen concentration adjustment mechanism to cause the oxygen concentration of the exhaust gas to be held at the first target concentration.14. The regeneration device as defined in claim 1, wherein the exhaust gas oxygen concentration adjustment mechanism comprises an intake fresh air amount adjustment mechanism which adjusts an intake fresh air amount of the internal combustion engine.15. The regeneration device as defined in claim 14, wherein the internal combustion engine comprises a turbocharger which boosts a charge amount of an intake fresh air of the internal combustion engine according to a boost pressure, and the intake fresh air amount adjustment mechanism comprises a variable geometry system which regulates the boost pressure of the turbocharger.16. The regeneration device as defined in claim 14, wherein the intake fresh air amount adjustment mechanism comprises an exhaust gas recirculation valve which recirculates a part of the exhaust gas into an intake air of the internal combustion engine.17. The regeneration device as defined in claim 14, wherein the intake fresh air amount adjustment mechanism comprises an intake throttle which regulates an intake fresh air amount of the internal combustion engine.18. The regeneration device as defined in claim 1, wherein the exhaust gas oxygen concentration adjustment mechanism comprises a fuel injection nozzle which injects fuel for combustion into the internal combustion engine.19. The regeneration device as defined in claim 18, wherein the controller further functions to cause the fuel injection nozzle to inject fuel for combustion in a main injection, and to perform a post injection to regulate the oxygen concentration of the exhaust gas.20. The regeneration device as defined in claim 19, wherein the exhaust gas oxygen concentration adjustment mechanism further comprises an intake throttle which regulates an intake fresh air amount of the internal combustion engine, according to an opening and the controller further functions to regulate the oxygen concentration of the exhaust gas by adjusting an amount of the post injection of the fuel injection nozzle and the opening of the intake throttle.21. The regeneration device as defined in claim 1, wherein the controller further functions to determine that the first phase is complete when an elapsed time from a start of the first phase reaches a predetermined duration.22. The regeneration device as defined in claim 1, wherein the controller further functions to determine that the second phase is complete when an elapsed time from a start of the second phase reaches a predetermined duration.23. The regeneration device as defined in claim 1, wherein the controller further functions to determine that the third phase is complete when an elapsed time from a start of the third phase reaches a predetermined duration.24. The regeneration device as defined in claim 1, wherein the controller further functions to determine whether or not a predetermined regeneration implementation condition is satisfied, and to interrupt control of the exhaust gas temperature adjustment mechanism and the exhaust gas oxygen concentration adjustment mechanism when the predetermined regeneration implementation is not satisfied.25. The regeneration device as defined in claim 24, wherein the controller further functions to restart controlling the exhaust gas temperature adjustment mechanism and the exhaust gas oxygen concentration adjustment mechanism when the regeneration implementation condition is satisfied after an interruption of control of the exhaust gas temperature adjustment mechanism and the exhaust gas oxygen concentration adjustment mechanism.26. The regeneration device as defined in claim 24, wherein the controller further functions to interrupt control of the exhaust gas temperature adjustment mechanism when the regeneration implementation is no longer satisfied in the first phase, to restart controlling the exhaust gas temperature adjustment mechanism when the regeneration implementation condition is satisfied after an interruption of control of the exhaust gas temperature adjustment mechanism in the first phase, while setting a duration of the first phase after a restart of control to be shorter as the temperature of the filter at the restart of control increases, and determining that the first phase is complete when an elapsed time from the restart of the control reaches the duration of the first phase after the restart of control.27. The regeneration device as defined in claim 26, wherein the regeneration device further comprises a sensor which detects an amount of trapped particulate matter in the filter, and the controller further functions to set a duration of the second phase to be longer as the amount of trapped particulate matter upon the restart of control in the first phase increases, and to determine that the second phase is complete when an elapsed time from a start of the second phase reaches the duration of the second phase.28. The regeneration device as defined in claim 24, wherein the regeneration device further comprises a sensor which detects an amount of trapped particulate matter in the filter, and the controller further functions to interrupt control of the exhaust gas temperature adjustment mechanism and the exhaust gas oxygen concentration adjustment mechanism when the regeneration implementation condition is no longer satisfied in the second phase, to restart controlling the exhaust gas temperature adjustment mechanism and the exhaust gas oxygen concentration adjustment mechanism when the regeneration implementation is satisfied after an interruption of control of the exhaust gas temperature adjustment mechanism and the exhaust gas oxygen concentration adjustment mechanism in the second phase, while setting a duration of the second phase after a restart of control to be longer as the amount of trapped particulate matter in the filter at the restart of control increases, and determining that the second phase is complete when an elapsed time from the restart of control reaches the duration of the second phase after the restart of control.29. The regeneration device as defined in claim 24, wherein the controller further functions to determine completion of the first phase, completion of the second phase, and completion of the third phase on the basis of an elapsed time from a start of the first phase, and when the regeneration implementation is no longer satisfied, functions to correct the elapsed time from the start of the first phase in a decreasing direction as an amount of time for which the regeneration implementation is not satisfied lengthens.30. The regeneration device as defined in claim 24, wherein the controller further functions to determine completion of the first phase, completion of the second phase, and completion of the third phase on the basis of an elapsed time from a start of the first phase, and functions, when the regeneration implementation is no longer satisfied in either of the second phase and the third phase, to correct the elapsed time from the start of the first phase in an increasing direction until an amount of time for which the regeneration implementation condition is not satisfied reaches a predetermined time, and to correct the elapsed time from the start of the first phase in a decreasing direction after the amount of time for which the regeneration implementation is not satisfied has exceeded the predetermined time.31. A regeneration device for a filter which traps particulate matter contained in the exhaust gas of an internal combustion engine, the particulate matter burning at a predetermined temperature, the device comprising:means for regulating a temperature of the exhaust gas; means for regulating an oxygen concentration of the exhaust gas; means for detecting a temperature of the filter; and means for controlling the exhaust gas temperature adjustment mechanism in a first phase such that the exhaust gas temperature is raised until the temperature of the filter rises to a predetermined temperature; means for controlling the exhaust gas oxygen concentration adjustment mechanism in a second phase following the first phase to cause the oxygen concentration of the exhaust gas to be held at a first target concentration while controlling the exhaust gas temperature adjustment mechanism to cause the temperature of the filter to be maintained at the predetermined temperature; and means for controlling the exhaust gas oxygen concentration adjustment mechanism in a third phase following the second phase to cause the oxygen concentration of the exhaust gas to be held at a second target concentration which is higher than the first target concentration while controlling the exhaust gas temperature adjustment mechanism to cause the temperature of the filter to be maintained at the predetermined temperature. 32. A regeneration method for a filter which traps particulate matter contained in the exhaust gas of an internal combustion engine, wherein the particulate matter burns at a predetermined temperature, and the engine comprises an exhaust gas temperature adjustment mechanism which regulates a temperature of the exhaust gas, an exhaust gas oxygen concentration adjustment mechanism which regulates an oxygen concentration of the exhaust gas and a sensor which detects a temperature of the filter, the method comprising:controlling the exhaust gas temperature adjustment mechanism in a first phase such that the exhaust gas temperature is raised until the temperature of the filter rises to a predetermined temperature; controlling the exhaust gas oxygen concentration adjustment mechanism in a second phase following the first phase to cause the oxygen concentration of the exhaust gas to be held at a first target concentration while controlling the exhaust gas temperature adjustment mechanism to cause the temperature of the filter to be maintained at the predetermined temperature; and controlling the exhaust gas oxygen concentration adjustment mechanism in a third phase following the second phase to cause the oxygen concentration of the exhaust gas to be held at a second target concentration which is higher than the first target concentration while controlling the exhaust gas temperature adjustment mechanism to cause the temperature of the filter to be maintained at the predetermined temperature.