Patent number 8596046 is assigned to Toyota Jidosha Kabushiki Kaisha (
The following quote was obtained by the news editors from the background information supplied by the inventors: "Known in the art is an internal combustion engine which arranges, in an engine exhaust passage, an NO.sub.x storage catalyst which stores NO.sub.x which is contained in exhaust gas when the air-fuel ratio of the inflowing exhaust gas is lean and which releases the stored NO.sub.x when the air-fuel ratio of the inflowing exhaust gas becomes rich, which arranges, in the engine exhaust passage upstream of the NO.sub.x storage catalyst, an oxidation catalyst which has an adsorption function, and which feeds hydrocarbons into the engine exhaust passage upstream of the oxidation catalyst to make the air-fuel ratio of the exhaust gas flowing into the NO.sub.x storage catalyst rich when releasing NO.sub.x from the NO.sub.x storage catalyst (for example, see Patent Literature 1).
"In this internal combustion engine, the hydrocarbons which are fed when releasing NO.sub.x from the NO.sub.x storage catalyst are made gaseous hydrocarbons at the oxidation catalyst, and the gaseous hydrocarbons are fed to the NO.sub.x storage catalyst. As a result, the NO.sub.x which is released from the NO.sub.x storage catalyst is reduced well."
In addition to the background information obtained for this patent, NewsRx journalists also obtained the inventors' summary information for this patent: "Technical Problem
"However, there is the problem that when the NO.sub.x storage catalyst becomes a high temperature, the NO.sub.x purification rate falls.
"An object of the present invention is to provide an exhaust purification system of an internal combustion engine which enables a high NO.sub.x purification rate to be obtained even if the temperature of the exhaust purification catalyst becomes a high temperature and which enables a high NO.sub.x purification rate to be obtained even if the oxygen concentration in the exhaust gas becomes high.
"Solution to Problem
"According to the present invention, there is provided an exhaust purification system of an internal combustion engine wherein an exhaust purification catalyst for reacting NO.sub.x contained in exhaust gas and reformed hydrocarbons is arranged inside of an engine exhaust passage, aqueous urea solution feeding means and an NO.sub.x selective reduction catalyst able to reduce NO.sub.x by ammonia derived from an aqueous urea solution fed are arranged inside of the engine exhaust passage downstream of the exhaust purification catalyst, a precious metal catalyst is carried on an exhaust gas flow surface of the exhaust purification catalyst and a basic exhaust gas flow surface part is formed amount the previous metal catalyst, the exhaust purification catalyst has a property of reducing the NO.sub.x which is contained in exhaust gas if a concentration of hydrocarbons flowing into the exhaust purification catalyst is made to vibrate by within a predetermined range of amplitude and within a predetermined range of period and has a property of being increased in storage amount of NO.sub.x which is contained in exhaust gas if the vibration period of the hydrocarbon concentration is made longer than the predetermined range, and, at the time of engine operation, either method of a first NO.sub.x purification method which makes the concentration of hydrocarbons flowing into the exhaust purification catalyst vibrate by within the predetermined range of amplitude and within the predetermined range of period so as to reduce the NO.sub.x which is contained in exhaust gas in the exhaust purification catalyst and a second NO.sub.x purification method which uses the ammonia derived from the fed aqueous urea solution to reduce the NO.sub.x which is contained in exhaust gas at the NO.sub.x selective reduction catalyst is selectively used.
"Advantageous Effects of Invention
"Even if the temperature of the exhaust purification catalyst becomes a high temperature, a high NO.sub.x purification rate can be obtained. Further, by selectively using the first NO.sub.x purification method and the second NO.sub.x purification method in accordance with the oxygen concentration in the exhaust gas, it is possible to obtain a high NO.sub.x purification rate even if the oxygen concentration in the exhaust gas changes."
URL and more information on this patent, see: Inoue, Mikio; Yoshida, Kohei; Bisaiji, Yuki; Umemoto, Kazuhiro. Exhaust Purification System of Internal Combustion Engine. U.S. Patent Number 8596046, filed
Keywords for this news article include: Urea, Chalcogens, Hydrocarbons, Organic Chemicals, Toyota Jidosha Kabushiki Kaisha.
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