Control of exhaust temperature in lean burn engines

Details Control of exhaust temperature in lean burn engines Control of exhaust temperature in lean burn engines

2000-02-23

2001-11-13

Nguyen, Hoang (Department: 3748)

Power plants

Fluid motor means driven by waste heat or by exhaust energy...

With supercharging means for engine

C060S605200, C415S047000

Reexamination Certificate

active

06314735

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to controlling the exhaust temperature of stratified direct injection and other lean burn engines in order to achieve desirable emission controls, and more particularly to using a variable geometry turbocharger to control the exhaust temperature.
BACKGROUND OF THE INVENTION
To achieve NO
x
control in lean burn engines, exhaust after-treatment systems have included an additional three-way catalyst, often referred to as a lean NO
x
trap (LNT). Presently, however, the performance of NO
x
trap technology is limited in several respects. NO
x
trap performance is affected by the operating temperature and requires a relatively narrow temperature-operating window. At temperatures outside this window, the device will not operate efficiently and NO
x
emissions will increase. Exposure to high temperature will also result in permanent degradation of the NO
x
trap capacity.
A current approach to controlling the temperature of the exhaust gas entering aftertreatment devices implements a variable geometry exhaust system having two exhaust paths. When the temperature is high, a valve sends the exhaust gas down a long path from the engine to the aftertreatment device, which provides additional cooling primarily by convection. Otherwise, the exhaust gas follows a shorter path that provides considerably less cooling. This system has limited flexibility, and is difficult to package in a limited space. It also adds cost and complexity to the emissions system, without significant additional benefits.
Governmental regulations of emissions are becoming more stringent. The efficiency of catalysts is temperature dependent. Thus, there exists a need for close control of the temperature of an exhaust after-treatment system to provide an effective means of reducing undesirable emissions.
SUMMARY OF THE INVENTION
It is an object of the present invention to actively enhance engine performance and improve fuel economy and emissions. It is another object of the present invention to use a variable geometry turbocharger to control exhaust temperature for that purpose.
It is a further object of the present invention to provide a control strategy for adjusting the temperature of the exhaust gas entering the aftertreatment device by carefully controlling the turbine inlet vane position.
The foregoing and other objects and advantages are achieved through the use of electronically controlled, variable position turbine inlet vanes in a variable geometry turbocharger. The turbine inlet vane position can control the amount of energy that is extracted and therefore control the temperature of the exhaust gas exiting the turbine. Through careful control of the turbine inlet vane position, the temperature of the exhaust gas entering the aftertreatment device may be maintained within the device operating temperature window to reduce emissions and realize a fuel economy benefit achieved through turbocharging.
One advantage of the present invention is that it reduces emissions and improves fuel economy. Other features and advantages of the present invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.


REFERENCES:
patent: 3079127 (1963-02-01), Rowlett et al.
patent: 3928971 (1975-12-01), Spath
patent: 4324526 (1982-04-01), Berchtold et al.
patent: 4404804 (1983-09-01), Tadokoro et al.
patent: 4415307 (1983-11-01), Fortmann
patent: 4553387 (1985-11-01), Mayer
patent: 4756285 (1988-07-01), Pischinger
patent: 4835963 (1989-06-01), Hardy
patent: 5021227 (1991-06-01), Kobayashi et al.
patent: 5050376 (1991-09-01), Stiglic et al.
patent: 5211010 (1993-05-01), Hirota
patent: 5267829 (1993-12-01), Schmidt et al.
patent: 5381659 (1995-01-01), Loving et al.
patent: 5669756 (1997-09-01), Brasz et al.
patent: 5778674 (1998-07-01), Kimura
patent: 0040217 (1977-03-01), None
patent: 0286817 (1990-11-01), None
patent: 405263628 A (1993-10-01), None

Affiliated with

Also associated with

Rating

Control of exhaust temperature in lean burn engines does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Control of exhaust temperature in lean burn engines, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control of exhaust temperature in lean burn engines will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2595294