초록 ▼

Improvements are described in the injection of ammonia (NH.sub.3) into the exhaust gases of an engine to reduce nitrogen oxides. Instead of merely injecting ammonia into the exhaust gas conduit through a hole in its side, an ammonia injector (90) is provided that projects considerably into the exhau

Improvements are described in the injection of ammonia (NH.sub.3) into the exhaust gases of an engine to reduce nitrogen oxides. Instead of merely injecting ammonia into the exhaust gas conduit through a hole in its side, an ammonia injector (90) is provided that projects considerably into the exhaust conduit (16), with the injector having a plurality of holes (94). The ammonia is activated to decompose it into its reactive components, including NH.sub.2 and NH prior to injecting it into the exhaust conduit. Such activation prior to injection can be accomplished by heating the ammonia in the presence of a catalyst such as a metal of the platinum group, iron, nickel, or zinc. In an engine that has a fuel injection system wherein electrical pulses are delivered to fuel injectors to control the fuel flow rate, the durations of these electrical signals are used to control the opening of a valve (72) that controls the flow rate of ammonia into the exhaust gas conduit.

대표청구항 ▼

[ What is claimed is:] [1.] In an engine which includes means for combusting hydrocarbons in air to produce work wherein said means also produces a stream of exhaust gasses that contain nitrogen oxides, with the engine having an exhaust conduit through which the exhaust gasses are passed before bein

[ What is claimed is:] [1.] In an engine which includes means for combusting hydrocarbons in air to produce work wherein said means also produces a stream of exhaust gasses that contain nitrogen oxides, with the engine having an exhaust conduit through which the exhaust gasses are passed before being emitted into the atmosphere, the improvement comprising:a source of ammonia;an injector apparatus coupled to said source to receive ammonia therefrom and inject the ammonia into said exhaust gas conduit;said injector apparatus including an ammonia-carrying conduit with an injector lying within said exhaust conduit, said injector having at least one opening through which said ammonia is injected into said stream of exhaust gasses;means for heating said ammonia and flowing said ammonia past a catalyzing material to activate the ammonia after the ammonia has left said source and before the ammonia has been injected into said exhaust conduit and before the ammonia comes in contact with said exhaust gases, so said ammonia is heated to decompose part of said ammonia before the ammonia with a decomposed part comes in contact with said exhaust gases. [9.] A method for controlling the injection of ammonia through an electrically operated valve into an exhaust gas conduit of an engine, where said engine includes a fuel injector and an electronic fuel injector circuit that generates fuel injection control currents whose average duration per unit of time determines the flow rate of fuel through said fuel injector, comprising:using said fuel injection control currents to control the opening of said valve to flow ammonia through said valve at a flow rate that is generally proportioned to the duration per unit of time of said injection control currents. In an engine which includes means for combusting hydrocarbons in air to produce work wherein said means also produces a stream of exhaust gases that contain nitrogen oxides, with the engine having an exhaust conduit through which the exhaust gases are passed before being emitted into the atmosphere, the improvement comprising:a source of ammonia;an injector apparatus coupled to said source to receive ammonia therefrom and inject it into said exhaust gas conduit;said injector apparatus including an ammonia-carrying body forming a plurality of ammonia-carrying passages that each has an average width and that each has an average cross-section of less than 1 mm.sup.2 and a length at least 10 times its average width;means for heating said body to decompose at least 10% of the ammonia being injected, prior to allowing said ammonia to come into contact with said exhaust gases of said stream of exhaust gases. The engine described in claim 10 wherein:said body includes catalyzing material to decompose said ammonia, with said catalyzing material lying along said passages. In an apparatus for receiving ammonia and injecting at least components of the ammonia into a stream of exhaust gasses of an engine the improvement, comprising:means for activating said ammonia to decompose at least 10% of the ammonia into ammonia components prior to injecting said activated ammonia into said stream of exhaust gasses, with said means for activating being constructed to isolate said ammonia from said stream of exhaust gasses until at least 10% of the ammonia that is being injected into the stream of exhaust gasses has already been decomposed prior to said injection;said means for activating including a body comprising material that is catalyzing to ammonia to decompose ammonia, said body lying in said stream of exhaust gasses, with said body having multiple parallel ammonia carrying passages that each have a length that lies within said stream of exhaust that is at least 10 times the average width of the passage. In an apparatus for receiving ammonia and injecting at least components of the ammonia into a stream of exhaust gasses of an engine the improvement, comprising:means for activating said ammonia to decompose at least 10% of the ammonia into ammonia components prior to injecting said activated ammonia into said stream of exhaust gasses, with said means for activating being constructed to isolate said ammonia from said stream of exhaust gasses until at least 10% of the ammonia that is being injected into the stream of exhaust gasses has already been decomposed prior to said injection;said means for activating comprising a body having multiple ammonia-carrying passages that each has a cross-section of less than 1 mm.sup.2 and a length at least 10 times its width, and an electrically powered heater coupled to said body to heat said body. A method for reducing nitrogen oxides in the exhaust gasses of an engine that combusts hydrocarbon in the presence of air and that produces a stream of exhaust gasses, comprising:passing ammonia from a source to an injector and injecting at least components of the ammonia from said injector, into said stream of exhaust gasses;activating said ammonia to break down at least 10% of said ammonia into components of ammonia, prior to injecting said ammonia and components into said stream of exhaust gasses and prior to allowing said ammonia to come into direct contact with said exhaust gases;said step of activating includes positioning a body with passage walls forming at least one elongated passage having a length at least 10 times its average diameter, so a length of said passage which is at least 10 times its average diameter lies in said stream of exhaust gases and allowing the heat of said exhaust gases to heat said passage walls, and passing said ammonia through said at least one passage prior to injecting said ammonia into said stream of exhaust gases to allow said passage walls to heat said ammonia to at least 500.degree. F. A method for reducing nitrogen oxides in the exhaust gasses of an engine that combusts hydrocarbon in the presence of air and that produces a stream of exhaust gasses, comprising:passing ammonia from a source to an injector and injecting at least components of the ammonia from said injector, into said stream of exhaust gasses;activating said ammonia to break down at least 10% of said ammonia into components of ammonia, prior to injecting said ammonia and components into said stream of exhaust gasses and prior to allowing said ammonia to come into direct contact with said exhaust gases;said step of activating includes heating said ammonia in the presence of a catalyst prior to said step of injecting and prior to allowing said ammonia to come into contact with said exhaust gases.