Power plants – Internal combustion engine with treatment or handling of... – Methods
Reexamination Certificate
1999-08-24
2001-05-29
Denion, Thomas (Department: 3748)
Power plants
Internal combustion engine with treatment or handling of...
Methods
C060S297000, C060S311000, C055SDIG003
Reexamination Certificate
active
06237326
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a system and method for controlling an engine having both a lean NOx catalyst for reducing exhaust NOx in an oxygen rich environment and a particulate filter for removing carbon particles, or soot.
BACKGROUND OF THE INVENTION
In order to meet future emission regulations in vehicles having a compression ignition engine, it may be necessary to use lean NOx catalysts in combination with particulate filters.
A NOx catalyst reduces NOx emissions continuously, even in an oxygen rich environment. For an active NOx catalyst to maximize NOx reduction, a reducing agent, for example, diesel fuel or urea, needs to be present. The optimum amount of reducing agent for the NOx catalyst is typically based on engine operating conditions and catalyst conditions. These conditions typically include engine speed, engine load, and catalyst temperature.
A particulate filter, also commonly used with compression ignition engines, is used to prevent soot, or carbon particles, from exiting the tailpipe. Since the particulate filter has a limited storage capacity, it is periodically regenerated. In one approach, during the regeneration process, exhaust temperature is increased to ignite carbon particles stored in the particulate filter. By burning the stored carbon particles, the filter is regenerated and able to again store the carbon particles. In addition, the burning of the carbon particles causes an increase in temperature.
One approach for managing a particulate filter estimates that amount of stored particulates and then regenerates the filter when this amount reaches a predetermined value. This decision can be augmented based on a vehicle operating zone defined by engine speed and load. Such a system is describe by EP 0 859 132.
The inventor herein has recognized numerous disadvantages when using prior particulate filter management systems when a NOx catalyst is present. In particular, the above management system does not consider the state of the NOx catalyst when determining filter regeneration. For example, the prior art does not consider conditions where heat generated from regeneration raise NOx catalyst temperature beyond appropriate limits.
SUMMARY OF THE INVENTION
An object of the present invention is to manage particulate regeneration system where an exhaust stream of a compression ignition engine is coupled to both a particulate filter and a lean NOx catalyst.
The above object is achieved and disadvantages of prior approaches overcome by a method for managing regeneration of a particulate filter communicating with an engine exhaust upstream of a catalyst, the method comprising: estimating an amount of stored particulates in the particulate filter; and regenerating the particulate filter dependent upon said amount and a condition of the catalyst.
By including catalyst conditions in regeneration of the particulate filter, it is possible coordinate operation of both the particulate filter and the catalyst, thereby improving performance of the overall system. Further, it is possible to avoid degradation of the catalyst using a catalyst condition in controlling regeneration of the particulate filter.
An advantage of the above aspect of the present invention is improved system durability.
Another advantage of the above aspect of the present invention is improved system performance.
REFERENCES:
patent: 4449362 (1984-05-01), Frankenberg et al.
patent: 5063736 (1991-11-01), Hough et al.
patent: 5193340 (1993-03-01), Kamihara
patent: 5195316 (1993-03-01), Shinzawa et al.
patent: 5195317 (1993-03-01), Nobue et al.
patent: 5207990 (1993-05-01), Sekiya et al.
patent: 5701735 (1997-12-01), Kawaguchi
patent: 5725618 (1998-03-01), Shimoda et al.
patent: 5746989 (1998-05-01), Murachi et al.
patent: 5826425 (1998-10-01), Sebastiano et al.
patent: 5850735 (1998-12-01), Araki et al.
patent: 5974791 (1999-11-01), Hirota et al.
patent: 6021639 (2000-02-01), Abe et al.
patent: 6032461 (2000-03-01), Kinugasa et al.
patent: 0070619 (1983-01-01), None
patent: 0859132 (1998-08-01), None
Denion Thomas
Ford Global Technolgies, Inc.
Russell John D.
Tran Diem
LandOfFree
Engine control system and method with lean catalyst and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Engine control system and method with lean catalyst and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Engine control system and method with lean catalyst and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2570342