Power plants – Internal combustion engine with treatment or handling of... – Having means analyzing composition of exhaust gas
Patent
1993-06-14
1995-12-12
Hart, Douglas
Power plants
Internal combustion engine with treatment or handling of...
Having means analyzing composition of exhaust gas
60285, 60297, 60301, F01N 320
Patent
active
054738873
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a exhaust purification device of an internal combustion engine.
BACKGROUND ART
A diesel engine in which an engine exhaust passage is branched to a pair of exhaust branch passages for purifying NO.sub.x, in which a switching valve is disposed at the branched portion of these exhaust branch passages to alternately guide the exhaust gas to one of the exhaust branch passages by a switching function of the switching valve, and in which a catalyst which can oxidize and absorb the NO.sub.x is disposed in each of the exhaust branch passages is well known (refer to Japanese Unexamined Patent Publication No. 62-106826). In this diesel engine, NO.sub.x in the exhaust gas introduced into one exhaust branch passage is oxidized and absorbed by the catalyst disposed in that exhaust branch passage. During this time, the inflow of the exhaust gas to the other exhaust branch passage is stopped and, at the same time, a gaseous reducing agent is fed into this exhaust branch passage. The NO.sub.x accumulated in the catalyst disposed in this exhaust branch passage is reduced by this reducing agent. Subsequently, after a short time, the introduction of the exhaust gas to the exhaust branch passage to which the exhaust gas had been introduced heretofore is stopped by the switching function of the switching valve, and the introduction of the exhaust gas to the exhaust branch passage to which the introduction of the exhaust gas had been stopped heretofore is started again.
However, when the introduction of the exhaust gas to a pair of exhaust branch passages is alternately stopped, the temperature of the catalyst in the exhaust branch passage on the side where the introduction of the exhaust gas was stopped is gradually lowered in the period where the introduction of the exhaust gas is stopped and is lowered to a considerably low temperature near the time when the introduction of the exhaust gas is started again. When the temperature of the catalyst becomes low in this way, there arises a problem in that the catalytic function of the catalyst is lowered, and therefore the oxidation and absorption function of NO.sub.x is not sufficiently carried out. In the period from when the introduction of the exhaust gas is started to when the catalyst temperature rises, the NO.sub.x is not absorbed by the catalyst and thus is discharged to the atmosphere.
Also, in this diesel engine, a pair of exhaust branch passages must be provided, and a switching valve becomes necessary. Therefore, the construction becomes complex. Further, the switching valve is always exposed to the high temperature exhaust gas, and therefore there arises a problem of durability of the switching valve. Also, from the viewpoint of the absorption of NO.sub.x, one catalyst is always idle, and therefore there is another problem such that the entire catalyst which is provided is not effectively utilized for the absorption of NO.sub.x.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide an exhaust purification device which can efficiently absorb NO.sub.x without a complex construction of the exhaust system and can release the absorbed NO.sub.x according to need.
According to the present invention, there is provided an exhaust purification device of an internal combustion engine wherein an NO.sub.x absorbent which absorbs the NO.sub.x when an air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent is lean, and which releases the absorbed NO.sub.x when the oxygen concentration in the exhaust gas flowing into the NO.sub.x absorbent is lowered is disposed in an engine exhaust passage, the exhaust gas continuously flows into the NO.sub.x absorbent during the operation of the engine, and the NO.sub.x absorbed in the NO.sub.x absorbent when the exhaust gas flowing into the NO.sub.x absorbent is lean is released from the NO.sub.x absorbent when the oxygen concentration in the exhaust gas flowing into the NO.sub.x absorbent is lowered.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an overall
REFERENCES:
patent: 3086353 (1963-04-01), Ridgway
patent: 3303003 (1967-02-01), Zimmer
patent: 3716996 (1973-02-01), Maruoka
patent: 3747346 (1993-07-01), Onoda et al.
patent: 3795730 (1974-03-01), Kalvinskas
patent: 3926590 (1975-12-01), Aibe et al.
patent: 4033123 (1977-07-01), Masaki et al.
patent: 4104361 (1978-08-01), Nishikawa et al.
patent: 4615173 (1986-10-01), Usui et al.
patent: 4760044 (1988-07-01), Joy, III et al.
patent: 4780447 (1988-10-01), Kim et al.
patent: 4868148 (1989-09-01), Henk et al.
patent: 5041407 (1991-08-01), Williamson et al.
patent: 5090200 (1992-02-01), Arai
patent: 5116800 (1992-05-01), Williamson et al.
patent: 5174111 (1992-12-01), Nomura
patent: 5189876 (1993-03-01), Hirota et al.
patent: 5207990 (1993-05-01), Sekiya et al.
patent: 5233830 (1993-08-01), Takeshima
patent: 5243819 (1993-09-01), Woerner et al.
patent: 5270024 (1993-12-01), Kasahara
patent: 5331809 (1994-07-01), Takeshima et al.
patent: 5343702 (1994-09-01), Miyajima
Araki Yasushi
Hirota Shinya
Iguchi Satoshi
Kobashi Kiyoshi
Nakanishi Kiyoshi
Hart Douglas
Toyota Jidosha & Kabushiki Kaisha
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