초록 ▼

A method for controlling diesel engine emissions is disclosed. The diesel engine's exhaust system has a NOxoxidation catalyst, a diesel particulate filter (DPF), and a lean NOxtrap (LNT). The DPF is monitored to determine the need for regeneration. The LNT is monitored to determine the need for rege

A method for controlling diesel engine emissions is disclosed. The diesel engine's exhaust system has a NOxoxidation catalyst, a diesel particulate filter (DPF), and a lean NOxtrap (LNT). The DPF is monitored to determine the need for regeneration. The LNT is monitored to determine the need for regeneration or desulfurization. A fuel injector is used to inject fuel upstream of the LNT under certain conditions, and a bypass may be used to bypass exhaust around the oxidation catalyst to provide richer or hotter exhaust to the LNT.

대표청구항 ▼

1. A method of reducing the amount of NOxand carbonaceous particulate matter in exhaust from an internal combustion engine, the method comprising: receiving the exhaust into a first stage, the first stage having a NOxoxidation catalyst adapted to oxidize the nitric oxide to nitrogen dioxide and d

1. A method of reducing the amount of NOxand carbonaceous particulate matter in exhaust from an internal combustion engine, the method comprising: receiving the exhaust into a first stage, the first stage having a NOxoxidation catalyst adapted to oxidize the nitric oxide to nitrogen dioxide and discharge exhaust; positioning a second stage in fluid communication with said first stage and adapted to receive said exhaust from said first stage, said second stage having a carbon trap adapted to store carbonaceous particulate material contained in the exhaust, and to discharge a gaseous stream containing at least nitrogen and carbon dioxide; interposing a bypass valve between the engine and the first stage, operable to bypass a portion of the exhaust around the first stage and upstream the second stage; positioning a third stage in fluid communication with said second stage and adapted to receive said exhaust from said second stage, said third stage having a lean NOxtrap adapted to store nitrogen dioxide discharged from said second stage, and to reduce at least a portion of the nitrogen dioxide; sensing when regeneration of the second stage is to be performed; regenerating the second stage, wherein regeneration of the second stage occurs without bypass of the first stage; sensing when regeneration of the third stage is to be performed regardless whether the step of regenerating the second stage is performed; and bypassing at least a portion of the exhaust around the first stage in response to the step of sensing when regeneration of the third stage is to be performed; during the bypassing step, regenerating the third stage; wherein regeneration of the third stage may occur even if the second stage does not require regeneration. 2. The method of claim 1, further comprising the step of interposing a hydrocarbon fuel injector between the first and second stages. 3. The method of claim 1, further comprising the step of sensing differential pressure at the second stage to determine the need for regeneration of the second stage. 4. The method of claim 1, further comprising the step of sensing temperature at the second stage to determine the need for regeneration of the second stage. 5. The method of claim 1, further comprising the step of regenerating the second stage by raising the temperature at the carbon trap. 6. The method of claim 1, further comprising the step of sensing NOxreduction across the third stage to determine the need for regeneration of the third stage. 7. The method of claim 1, wherein reaenerating the third stage is performed by raising temperature at the third stage. 8. The method of claim 1, further comprising the step of sensing NOxreduction across the third stage to determine the need for desulfurization of the third stage. 9. The method of claim 1, further comprising the step of desulfurizing the third stage by raising temperature at the third stage. 10. The method of claim 1, wherein the step of regenerating the third stage is performed by injecting fuel upstream of the second stage and downstream of the first stage. 11. The method of claim 1, wherein the third stage is regenerated by one or more of the following operations: intake throttling, increased exhaust gas recirculation, or post-combustion fuel injection. 12. The method of claim 1, wherein the first stage and second stage form a continuously regenerating carbon trap. 13. The method of claim 1, wherein regenerating the third stage is performed by increasing carbon monoxide at the third stage. 14. The method of claim 1, further comprising the step of continuously regenerating the second stage. 15. The method of claim 14, wherein the step of continuously regenerating is in response to monitoring the balance point temperature at the second stage. 16. The method of claim 14, wherein the regenerating is performed by adjusting the air-fuel ratio in the exhaust.