High efficiency conversion of nitrogen oxides in an exhaust aftertreatment device at low temperature

a nitrogen oxide and aftertreatment device technology, applied in the direction of machines/engines, electric control, separation processes, etc., can solve the problem of significantly less reductant supplied to the catalyst, and achieve the effect of reducing the amount of reductant or discontinuing the delivery

Inactive Publication Date: 2005-01-13
XU LIFENG +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for controlling reductant addition to exhaust gases of an internal combustion engine. By supplying reductant when the temperature in the catalyst is greater than about 300°C, the NOx conversion efficiency of a lean NOx catalyst can be significantly increased. The method also allows for less reductant delivery and reduces the amount of reductant that slips through the catalyst into the tailpipe. These technical effects provide improved performance and efficiency of the engine's exhaust system.

Problems solved by technology

Furthermore, significantly less reductant is supplied to the catalyst than prior art methods.

Method used

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  • High efficiency conversion of nitrogen oxides in an exhaust aftertreatment device at low temperature
  • High efficiency conversion of nitrogen oxides in an exhaust aftertreatment device at low temperature
  • High efficiency conversion of nitrogen oxides in an exhaust aftertreatment device at low temperature

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Embodiment Construction

[0018] In FIG. 1, an internal combustion engine 10 is supplied air through an intake line in which a throttle valve 14 may be disposed. Position of throttle valve 14 may be controlled by an electronic control unit (ECU) 40. A mass airflow sensor 18 may be placed in the intake line, supplying a signal to ECU 40 indicative of intake airflow into engine 10. Alternatively, a speed density system may be used to infer intake airflow. Speed density relies on a sensor in the intake system providing an indication of pressure in the intake manifold and an engine speed sensor, shown as other sensors 42. Engine 10 is supplied fuel by injectors 12 (fuel supply to injectors 12 not shown). Fuel injection timing and duration may be controlled by mechanical means. More commonly, however, the fuel injection system is of a type, eg., common rail design, which allows timing and duration to be controlled by ECU 40. Engine 10 may be equipped with an exhaust gas recirculation (EGR) system, which connects ...

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Abstract

A system and method for providing reductant to a lean NOx catalyst, when the temperature in the lean NOx catalyst is greater than 300° C., is disclosed. After the reductant is supplied under these conditions, the NOx conversion efficiency of the lean NOx catalyst in the 140-250° C. temperature range is increased.

Description

BACKGROUND OF INVENTION [0001] The present invention relates to a system and a method for improving conversion efficiency of a lean NOx catalyst in a diesel or lean burn gasoline engine, and, more particularly, to improving conversion efficiency by controlling delivery of a NOx reductant. [0002] Internal combustion engines commonly rely on exhaust aftertreatment devices to convert regulated components: carbon monoxide, hydrocarbons, and nitrogen oxides (NOx), into carbon dioxide, water, nitrogen, and oxygen. Exhaust catalysts have been extensively developed to obtain high conversion efficiencies on stoichiometric exhaust gases. Stoichiometric conditions are achieved when the fuel and oxidizer supplied to the engine is in a proportion which, if reaction of the fuel were complete, produce carbon dioxide, water, and nitrogen. It is known to those skilled in the art, though, that higher fuel efficiency is obtained from engines operating at air-fuel ratios lean of stoichiometric, that is...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): F02D45/00B01D53/94F01N3/08F01N3/20F01N3/28F02D21/08F02D41/38F02D41/40
CPCB01D53/86B01D53/9495B01D2257/404F01N3/0842F01N3/0871F01N3/2013Y02T10/26F01N2560/023F01N2570/18F01N2610/02F02D41/005F02D2041/1468F01N2560/021Y02T10/12
InventorXU, LIFENGMCCABE, ROBERT WALTER
OwnerXU LIFENG