Power plants – Internal combustion engine with treatment or handling of... – Methods
Patent
1997-01-22
1999-09-28
Denion, Thomas E.
Power plants
Internal combustion engine with treatment or handling of...
Methods
60284, 60285, F01N 300
Patent
active
059569425
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of activating a Denox catalyst of a diesel engine with a rail injection system.
BACKGROUND ART
As is known, to safeguard the environment, increasing effort is being made, and in many countries tighter restrictions are being imposed, to control the exhaust of internal combustion engines.
As regards diesel engines in particular, the main problems are due to the presence in the exhaust gas of nitric oxides (NO .sub.x) and particulates, as opposed to a very low content of carbon monoxide (CO) and hydrocarbons (HC).
Nitric oxides in particular are currently believed to be a serious source of pollution, by contributing towards and increasing the formation of the so-called "hole" in the ozone layer, and by forming, in the presence of sunlight, aggressive products resulting in various human (eye and skin) ailments and in damage to various types of material.
Various nitric oxide reducing systems are therefore being researched, one of which (EGR system) provides for recirculating the burnt gases, but is insufficient to meet stricter future requirements. Research is also being conducted into so-called DENOX e.g. zeolite, catalysts, which have a reducing effect and assist the reaction between the nitric oxides and other exhaust gas components. Such catalysts, however, are in themselves only moderately effective, so that additional steps must be taken to achieve a really effective reduction in nitric oxide. In particular, the efficiency of the reduction reaction has been found to be greatly improved in the presence of hydrocarbons which participate directly in the catalytic nitric oxide reducing action of the zeolites; and since diesel fuel has been found to be one of the best performing hydrocarbons, a solution has been devised whereby diesel fuel is injected upstream from the Denox catalyst, where it mixes with the exhaust gas to assist the catalyst reaction.
Though it does in fact improve the efficiency of the Denox catalyst, the above solution requires design alterations to the exhaust system to accommodate the injection assembly and connect it to the fuel tank, as well as specific injection control elements involving considerable cost and "ad hoc" setup.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a straightforward method of improving the efficiency of currently researched Denox catalysts, and which is both easy to implement and requires no alterations to the exhaust system.
According to the present invention, there is provided a method of activating the Denox catalyst of a diesel engine featuring a rail injection system comprising a main injection phase; characterized in that it comprises an auxiliary post-injection phase during at least part of the exhaust stroke of the engine.
BRIEF DESCRIPTION OF DRAWINGS
A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
FIG. 1 shows a block diagram of a known diesel engine injection system;
FIG. 2 shows a graph of pressure and injection, in relation to the engine strokes, according to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows schematically a diesel engine rail injection system 1 of the type to which the present invention relates. Of system 1, only the parts pertinent to the present invention are shown, the fuel conduits being indicated by continuous lines, and the dotted lines indicating the electric lines supplying the control and measured quantity signals.
System 1 comprises: 4; 2; more elements for connection to the injectors; to rail 9; components on the basis of signals from various sensors, memorized maps, and the control strategy implemented; (not shown) of engine 12; downstream section operating as an oxidizing catalyst; and
Pressure regulator 6, injectors 10, pressure sensor 20, engine speed and stroke sensor 22, and cycle sensor 24 are connected to central unit 16 over electric data and control exchange lines.
According to the pr
REFERENCES:
patent: 4452040 (1984-06-01), Kobashi
patent: 4509327 (1985-04-01), Enga
patent: 5207058 (1993-05-01), Sasaki et al.
patent: 5343702 (1994-09-01), Miyajima et al.
patent: 5479775 (1996-01-01), Kraemer et al.
Patent Abstract of Japan, vol. 17, No. 558 (M-1493), Oct. 7, 1993 for JP 05-156993.
Patent Abstract of Japan, vol. 18, No. 408 (M-1647), Jul. 29, 1994 for JP 06-117228.
Patent Abstract of Japan, vol. 14, No. 174 (M-0959), Apr. 5, 1990 for JP 02-027177.
Canale Silvio
Rossi Sebastiano Giovanni Maria
C.R.F. Societa Consortile per Azioni
Denion Thomas E.
LandOfFree
Method for increasing the efficiency of a catalyst in a diesel e does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for increasing the efficiency of a catalyst in a diesel e, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for increasing the efficiency of a catalyst in a diesel e will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-691438