In an internal combustion engine, a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged in an engine exhaust passage. A first NO X removal method which injects hydrocarbons from the hydrocarbon feed valve (15) within a predetermined range of period so that the reducing intermediate generated thereby reduces the NO X contained in the exhaust gas and a second NO X removal method which makes the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst (13) a first target rich air-fuel ratio by a period which is longer than this predetermined range are used. When the NO X removal method is switched from the second NO X removal method to the first NO X removal method, the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst (13) is made a second target air-fuel ratio which is smaller than the first target rich air-fuel ratio.

Exhaust purification system of internal combustion engine

An object of the invention is to provide an exhaust emission control device which eliminates the use of a heat-retention structure using heat-insulating material such as glass wool so as to attain substantial lessening in production cost. A discharge end of a gas gathering chamber is connected to an entry end of a mixing pipe so as to encase the entry end of the mixing pipe and close an opened end face in a required spaced-apart relationship. Moreover, a side surface of the entry end of the mixing pipe adjacent to the discharge side of the particulate filter is formed with an opening; and gas guide passages are formed in the gas gathering chamber by guide fins for tangential introduction of all of the exhaust gas from the discharge side of the particulate filter to the opening. An extra space isolated from the gas guide passages is ensured in the gas gathering chamber as a heat-retention chamber surrounding the entry end of the mixing pipe.

Exhaust emission control device

Catalysts, methods of preparing catalyst, and methods for treating exhaust gas streams are described. Tn one or more embodiments, a catalyst system includes an upstream zone effective to catalyze the conversion of a mixture of NOx and NH3 to N2, and a downstream zone effective for the conversion of ammonia to N2 in the presence or absence Of NOx. In an embodiment, a method for preparing a catalyst system includes: first coating one end of a substrate along at least 5% of its length with an undercoat washcoat layer containing a material composition effective to catalyze the removal of ammonia; second coating with an overcoat layer containing a material composition effective to catalyze the conversion of a mixture of NOx and NH3 to N2. A method for treating the exhaust gas stream is provided, which includes injecting ammonia or an ammonia precursor into an exhaust gas stream of a vehicle, passing the engine exhaust gas stream containing NOx and NH3 through the upstream zone of a catalyst system to remove NOx and then passing the exhaust gas stream through the downstream zone of the catalyst system to remove NH3, as well as other oxidizable species such as hydrocarbons and CO.

Integrated scr and amox catalyst systems

An exhaust emission control device of an internal combustion engine, wherein an exhaust emission control valve (24) disposed in an exhaust pipe (22) of the internal combustion engine is approximately fully closed at the time of start and during the warming-up of the engine, the injection amount of a main fuel is increased over an optimum injection amount for fully opened exhaust emission control valve, and an auxiliary fuel is additionally injected during an expansion stroke, whereby unburned HC exhausted into the atmosphere at the start and during the warming-up of the engine is reduced remarkably.

Exhaust emission control device of internal combustion engine

In an exhaust emission purifying apparatus for reductively purifying NOx in the exhaust emission by using a liquid reducing agent or its precursor, to be referred to as “liquid reducing agent” herein, a dosing flow rate of the liquid reducing agent according to engine operating conditions is computed, and the dosing of the liquid reducing agent is controlled based on the computed dosing flow rate, and also, it is judged whether or not a supply system of the liquid reducing agent is failed, based on a ratio between an integrated amount obtained by sequentially integrating the dosing flow rate and a consumed amount of the liquid reducing agent.

Exhaust Emission Purifying Apparatus for Engine

In order to suppress deposition of constituent of a reducing agent (dissolved matter) in an exhaust passage of an engine enhancing an elimination rate of NOx even when temperature of an exhaust emission from the engine is low, an exhaust emission purifying apparatus is provided with an electro-generative-heat carrier provided on an upstream side of an injection nozzle that supplies the reducing agent into the exhaust emission on upstream side of a reduction catalyst in an exhaust pipe, the exhaust emission being heated to a temperature equal to or higher than a melting point of the dissolved matter whereby deposition of the dissolved matter on an inner wall surface of the exhaust pipe is suppressed to effectively use the supplied reducing agent for catalytic reduction reaction, even when the exhaust emission temperature is lower than the melting point of the dissolved matter of the reducing agent.

Exhaust emission purifying apparatus for engine

A reducing agent supplied into an exhaust gas passage adheres to the exhaust passage and a component of the reducing agent deposits thereon. Disclosed is a device for purifying exhaust gases of engines wherein such a component of the reducing agent deposited on the exhaust gas passage can be removed. A device for purifying exhaust gases of engines comprises a reduction catalyst (5) which is arranged in an engine exhaust system and reduces nitrogen oxides in the exhaust gas with a reducing agent, a spray nozzle (7) for supplying the reducing agent as a spray in the exhaust upstream of the reduction catalyst (5) in an exhaust pipe (3) of the exhaust system, and a reducing agent supply unit (8) for supplying the reducing agent to the spray nozzle (7). In this exhaust gas purifying device, a recessed portion (14) is formed in the inner wall of the lower part of the exhaust pipe (3) by forming a hollow in a portion where the reducing agent sprayed from the spray nozzle (7) adheres. This recessed portion (14) has a removable bottom wall (15).

Tatsuji Miyata

Papers

Exhaust emission purifying apparatus for engine

Device for purifying exhaust gas of engine