Exhaust purification device of an internal combustion engine

Details Exhaust purification device of an internal combustion engine Exhaust purification device of an internal combustion engine

1993-08-26

1995-05-09

Hart, Douglas

Power plants

Internal combustion engine with treatment or handling of...

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

60286, 60297, 60301, 4232137, F01N 328

Patent

active

054129451

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to an 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, containing a switching valve which is disposed at the branching portion of the 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 a catalyst which can oxidize and absorb the NO.sub.x and which 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.
In such a catalyst, to properly oxidize and absorb NO.sub.x, it is necessary to increase the amount of alkali metals, alkali-earth metals or rare-earth metals to more than a given amount. However, if the amount of alkali metals, alkali-earth metals or rare-earth metals is increased, the alkalinity is increased and, as a result, the reducing force of the catalyst is weakened. Accordingly, when NO.sub.x absorbed in the NO.sub.x absorbent should be reduced, NO.sub.x cannot be sufficiently reduced, and thus a problem arises in that a large amount of NO.sub.x is discharged into the outside air without being reduced.


DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an exhaust purification device of an internal combustion engine, which prevents NO.sub.x, discharged from the internal combustion engine, from being discharged into the outside air.
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 NO.sub.x when an air-fuel ratio of an inflowing exhaust gas is lean and releases an absorbed NO.sub.x when the oxygen concentration of the inflowing exhaust gas is lowered is arranged in an exhaust passage of the engine, and an amount of alkali metals, alkali-earth metals or rare-earth metals, contained in the NO.sub.x absorbent positioned on the downstream side, is made lower than an amount of alkali metals, alkali-earth metals or rare-earth metals, contained in the NO.sub.x absorbent positioned on the upstream side, to increase the reducing power of the NO.sub.x absorbent positioned on the downstream side as compared to a reducing power of the NO.sub.x absorbent positioned on the upstream side, NO.sub.x absorbed in the NO.sub.x absorbent being released from the NO.sub.x absorbent when the oxygen concentration of the exhaust gas flowing into NO.sub.x absorbent is lowered.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall view of an internal combustion engine; FIG. 2 is an enlarged cross-sectional side view illustrating a first embodiment of an NO.sub.x absorbent; FIG. 3 is an enlarged cross-sectional side view illustrating a second embodiment of an NO.sub.x absorbent; FIG. 4 is a diagram showing a map of a basic fuel injection time; FIG. 5 is a diagram showing a change of a correction coefficient K; FIG. 6 is a graph schematically showing the concentration of unburnt HC and CO and oxygen in the exhaust gas discharged from the engine; FIG. 7 is a diagram for explaining

REFERENCES:
patent: 3795730 (1974-03-01), Kalvinskas
patent: 3926590 (1975-12-01), Aibe 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: 5116800 (1992-05-01), Williamson et al.
patent: 5174111 (1992-12-01), Nomura
patent: 5270024 (1993-12-01), Kasahara
NO Removal by Absorption into BaO-CuO Binary Oxides, Masato Machida, et al., J. Chem. Soc., Chem. Commun., 1990, pp. 1165-1166.
Formation and Decomposition of BaCuO.sub.2.5 Prepared from a Mixture of Nitrates, Masato Machida, et al., Journal of Solid State Chemistry, 1991, pp. 176-179.
NO Removal by Absorption into Ba-Cu-O Binary Oxides, Masato Machida, et al., Catalyst, vol. 33, No. 2, pp. 87-90.

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