Exhaust gas purification device

Details Exhaust gas purification device Exhaust gas purification device

1999-07-27

2001-05-22

Denion, Thomas (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

By means producing a chemical reaction of a component of the...

C060S295000, C060S288000, C060S291000, C060S301000, C060S311000, C055SDIG003

Reexamination Certificate

active

06233927

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an exhaust gas purification device.
2. Description of the Related Art
For example, Unexamined Japanese Patent Publication No. 9-53442 discloses an exhaust gas purification device, which comprises an absorbent arranged in an exhaust passage of an engine for absorbing NO
x
when an air-fuel ratio of an exhaust gas flowing thereinto is lean, the absorbent discharging NO
x
absorbed therein when a concentration of an oxygen in the exhaust gas decreases. The absorbent is used in an engine which discharges an exhaust gas, the air-fuel ratio of which is lean in the major range of the engine operation.
As mentioned above, the absorbent discharges NO
x
absorbed therein when the concentration of the oxygen in the exhaust gas is decreased by HC and CO, and the absorbent purifies NO
x
with HC and CO. Further, the purification device comprises a trapping filter arranged in the exhaust passage upstream of the absorbent for trapping exhaust particulates.
The absorbent may also absorb SO
x
in the exhaust gas. In this case, the capacity of the absorbent to absorb NO
x
therein is decreased. However, SO
x
may absorb on the particulates trapped in the trapping filter. Thus, in the above purification device, SO
x
does not flow into the absorbent. Therefore, the trapping filter can maintain the capacity of the absorbent to absorb NO
x
therein.
The particulates may clog the trapping filter. In this case, the trapping filter restricts the flow of the exhaust as to the downstream of the trapping filter. To prevent this restriction, the trapping filter is regenerated by burning the particulates in the trapping filter when a predetermined period has elapsed.
SO
x
adsorbed on the particulates is discharged from the trapping filter when the trapping filter is regenerated. Thus, the capacity of the absorbent to absorb NO
x
is decreased when the trapping filter is regenerated.
Therefore, the object of the invention is to prevent the capacity of the absorbent to absorb NO
x
from being decreased when the trapping filter is regenerated.
SUMMARY OF THE INVENTION
According to the invention, there is provided an exhaust gas purification device comprising a NO
x
absorbent arranged in an exhaust passage of an engine for absorbing NO
x
therein when an air-fuel ratio of an exhaust gas flowing into the NO
x
absorbent is lean, the NO
x
absorbent discharging NO
x
absorbed therein when a concentration of the oxygen in the exhaust gas flowing into the NO
x
absorbent decreases, a trapping element arranged in the exhaust passage upstream of the NO
x
absorbent for trapping particulates, a processing element for processing the particulates trapped in the trapping element to regenerate the trapping element, and a preventing element for preventing the exhaust gas from flowing into the NO
x
absorbent from the trapping element when the trapping element is regenerated.
Further, according to the invention, the preventing element has an exhaust gas bypass passage branched from a portion of the exhaust passage between the trapping element and the absorbent for bypassing the NO
x
absorbent, and a flow direction changing valve for changing a flow direction of the exhaust gas between the flow directions directed to the NO
x
absorbent and to the exhaust gas bypass passage, and the flow direction changing valve is controlled to change the flow direction of the exhaust gas from the flow direction directed to the NO
x
absorbent to the flow direction directed to the exhaust gas bypass passage when the regeneration of the trapping element is carried out.
Further, according to the invention, the trapping element has a trapping filter.
Further, according to the invention, the processing element has a heater for heating the trapping element to burn the particulates trapped in the trapping element.
According to the invention, there is provided an exhaust gas purification device, comprising a NO
x
absorbent arranged in an exhaust passage of an engine for absorbing NO
x
therein when an air-fuel ratio of an exhaust gas flowing into the NO
x
absorbent is lean, the NO
x
absorbent discharging NO
x
absorbed therein when a concentration of the oxygen in the exhaust gas flowing into the NO
x
absorbent decreases, a trapping element arranged in the exhaust passage upstream of the NO
x
absorbent for trapping particulates, and a discharging element for discharging the particulates from the trapping element.
Further, according to the invention, an additional trapping element is arranged in the exhaust passage downstream of the NO
x
absorbent for trapping the particulates discharged by the discharging element.
Further, according to the invention, the additional trapping element has a trapping filter.
Further, according to the invention, the trapping element has a trapping filter.
According to the invention, there is provided an exhaust gas purification device, comprising a NO
x
absorbent arranged in an exhaust passage of an engine for absorbing NO
x
therein when an air-fuel ratio of an exhaust gas flowing into the NO
x
absorbent is lean, the NO
x
absorbent discharging NO
x
absorbed therein when a concentration of the oxygen in the exhaust gas flowing into the NO
x
absorbent decreases, a trapping element arranged in the exhaust passage upstream of the NO
x
absorbent for trapping particulates, a processing element for processing the particulates trapped in the trapping element to regenerate the trapping element, and an air-fuel ratio control element for controlling the air-fuel ratio of the exhaust gas flowing into the NO
x
absorbent to make the air-fuel ratio a stoichiometric ratio or rich when the regeneration of the trapping element is carried out.
Further, according to the invention the air-fuel ratio control element has bypass passage branched from the exhaust passage upstream of the trapping element and connected to the exhaust passage downstream of the trapping element for bypassing the trapping element, and a flow direction changing valve for changing a flow direction of the exhaust gas between the flow directions directed to the trapping element and to the exhaust gas bypass passage, and the flow direction changing valve is controlled to change the flow direction of the exhaust gas from the flow direction directed to the trapping element to the flow direction directed to the exhaust gas bypass passage when the regeneration of the trapping element is carried out.
Further, according to the invention the trapping element has a trapping filter.
Further, according to the invention the processing element has a heater for heating the trapping element to burn the particulates trapped in the trapping element.
The present invention may more fully understood from the description of the preferred embodiments of the invention set forth below, together with the accompanying drawings.


REFERENCES:
patent: 4485621 (1984-12-01), Wong et al.
patent: 5473890 (1995-12-01), Takeshima et al.
patent: 5524433 (1996-06-01), Adamczyk et al.
patent: 5603216 (1997-02-01), Guile et al.
patent: 5713199 (1998-02-01), Takeshima et al.
patent: 5738832 (1998-04-01), Dogahara et al.
patent: 5937637 (1999-08-01), Fujishita et al.
patent: 5974791 (1999-11-01), Hirota et al.
patent: 0020766 (1981-01-01), None
patent: 0540280 (1993-05-01), None
patent: 0758713 (1997-02-01), None
patent: 358222907A (1983-12-01), None
patent: 406066133A (1994-03-01), None
patent: 406229324A (1994-08-01), None
patent: 6346768A (1994-12-01), None
patent: 07174018A (1995-07-01), None
patent: 953442A (1997-02-01), None
Patent Abstracts Of Japan, vol. 018, No. 691 (M-1731), Dec. 26, 1994 (Dec. 12, 1994) & JP 06 272541 A (Toyota Motor Corp.), Sep. 27, 1994 (Sep. 27, 1994).

Affiliated with

Also associated with

Rating

Exhaust gas purification device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Exhaust gas purification device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Exhaust gas purification device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2467025