Patent•
Device for purifying exhaust gas of engine
24 Aug 1998-
TL;DR: In this paper, a plurality of the cylinders are divided into a first cylinder group and a second cylinder group, and each cylinder group is connected, via a corresponding branch exhaust passage, to a common interconnecting exhaust passage.
Abstract: An engine has a plurality of the cylinders. The cylinders are divided into a first cylinder group and a second cylinder group, and each cylinder group is connected, via a corresponding branch exhaust passage, to a common interconnecting exhaust passage. In the interconnecting exhaust passage, an exhaust gas purifying catalyst is arranged. The air-fuel ratio of the exhaust gas of the first cylinder group is made lean to feed oxygen to the exhaust gas purifying catalyst, and the air-fuel ratio of the second cylinder group is made rich to feed fuel for heating to the exhaust gas purifying catalyst, so that the oxygen and the fuel for heating react with each other to heat the exhaust gas purifying catalyst to reactivate the exhaust gas purifying catalyst when the reactivation of the exhaust gas purifying catalyst is must be performed. In each branch exhaust passage, a start catalyst is arranged.
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17 Sep 1999TL;DR: In this article, a converter containing a NOx absorbing and reducing catalyst is disposed in the exhaust passage of an internal combustion engine, where the upstream half portion (portion of the inlet side) of the substrate carries the oxygen storage component that absorbs oxygen in exhaust gas and releases the absorbed oxygen when the air-fuel ratio of the exhaust gas flowing in is rich.
Abstract: A converter containing a NOx absorbing and reducing catalyst is disposed in the exhaust passage of an internal combustion engine. The upstream half portion (portion of the inlet side) of the substrate of the NOx absorbing and reducing catalyst in the converter carries the oxygen storage component that absorbs oxygen in the exhaust gas when the air-fuel ratio of the exhaust gas is lean and releases the absorbed oxygen when the air-fuel ratio of the exhaust gas flowing in is rich in addition to carrying the NOx absorbing and reducing catalyst. After NOx is absorbed by the NOx absorbing and reducing catalyst as a result of operating the engine at a lean air-fuel ratio, the engine is operated at a rich air-fuel ratio, so that NOx is released from the NOx absorbing and reducing catalyst and is purified by reduction. Here, oxygen is released from the oxygen storage component carried by the upstream half portion of the substrate and is reacted with the H 2 and CO components in the exhaust gas, so that the temperature of the NOx absorbing and reducing catalyst is raised within short periods of time due to the heat of reaction. Therefore, the catalyst exhibits increased activity and the NOx absorbing and reducing catalyst exhibits improved NOx purification capability.
494 citations
Patent•
23 Jul 2001TL;DR: In this paper, an exhaust gas purification device having a NOx absorbent includes a by-pass passage for bypassing the NOx absorbing material, a flow rate control portion for regulating both the flow rate of exhaust gas passing through the bypass passage and bypassing the absorbent material, and a reductant addition portion for adding REDCTant into an exhaust passage upstream of the NOX absorbent.
Abstract: An exhaust gas purification device having a NOx absorbent includes a by-pass passage for by-passing the NOx absorbent, an exhaust gas flow rate control portion for regulating both a flow rate of exhaust gas flowing to the NOx absorbent and the flow rate of the exhaust gas bypassing the NOx absorbent, and a reductant addition portion for adding reductant into an exhaust passage upstream of the NOx absorbent In this device, when it is necessary to discharge sulfur components from the NOx absorbent, a temperature rise control is executed such that a temperature of the NOx absorbent becomes higher than a predetermined temperature Next, a rich condition control is executed such that an air-fuel ratio of the exhaust gas flowing to the NOx absorbent becomes one of a substantially stoichiometric condition and a rich condition The flow rate of the exhaust gas to the NOx absorbent during the temperature rise control is controlled so as to be higher than that during the rich condition control
235 citations
Patent•
09 Jun 2005TL;DR: In this article, a first cylinder and a second cylinder are connected by a communicating pipe connecting the intermediate portion of the first exhaust pipe with an intermediate part of the second exhaust pipe, and an exhaust gas control catalyst is arranged downstream of the portion to which the communicating pipe is connected.
Abstract: A first cylinder and a second cylinder are provided. A first exhaust pipe is connected to the first cylinder and a second exhaust pipe is connected to the second cylinder. A communicating pipe connects together an intermediate portion of the first exhaust pipe with an intermediate portion of the second exhaust pipe. An exhaust gas control catalyst is arranged in the second exhaust pipe downstream of the portion to which the communicating pipe is connected. Exhaust gas amount reducing devices are provided which reduce the amount of exhaust gas that flows from the first exhaust pipe into the second exhaust pipe through the communicating pipe during execution of rich/lean burn control which performs combustion with an air-fuel ratio of an air-fuel mixture that is richer than the stoichiometric air-fuel ratio in one of the first cylinder and second cylinder and performs combustion with an air-fuel ratio of an air-fuel mixture that is leaner than the stoichiometric air-fuel ratio in the other cylinder.
201 citations
Patent•
09 Mar 2007TL;DR: In this paper, the NH 3 -SCR catalyst was used to remove ammonia and enhance net NOx conversion by placing an NH 3-SCR formulation downstream of a lean NOx trap.
Abstract: This catalyst system simultaneously removes ammonia and enhances net NOx conversion by placing an NH 3 -SCR catalyst formulation downstream of a lean NOx trap. By doing so, the NH 3 -SCR catalyst adsorbs the ammonia from the upstream lean NOx trap generated during the rich pulses. The stored ammonia then reacts with the NOx emitted from the upstream lean NOx trap—enhancing the net NOx conversion rate significantly, while depleting the stored ammonia. By combining the lean NOx trap with the NH 3 -SCR catalyst, the system allows for the reduction or elimination of NH 3 and NOx slip, reduction in NOx spikes and thus an improved net NOx conversion during lean and rich operation.
190 citations
Patent•
20 Dec 2002TL;DR: In this paper, a method of selectively catalyzing the reduction of NO x in an exhaust gas flowing in an internal combustion engine comprising a filter for particulate matter comprising a catalyst capable of selectively catalysing the reduction with a reducing agent was proposed.
Abstract: A method of selectively catalysing the reduction of NO x in an exhaust gas flowing in an exhaust system of an internal combustion engine comprising a filter ( 40 ) for particulate matter comprising a catalyst capable of selectively catalysing the reduction of NO x with a reducing agent, which method comprising introducing a reducing agent, or a precursor thereof, into the exhaust gas and contacting the resulting gas with the filter ( 40 ).
164 citations
References
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10 Aug 1836
1,859 citations
Patent•
25 Feb 2008TL;DR: In this article, an internal combustion engine with an HC treatment catalyst having the function of adsorbing the HC in the exhaust gas is arranged upstream of the NOx selective reducing catalyst.
Abstract: An internal combustion engine wherein an HC treatment catalyst (12) having the function of adsorbing the HC in the exhaust gas is arranged upstream of the NOx selective reducing catalyst (14), an urea aqueous solution fed from the reducing agent feed valve (15) is arranged upstream of the HC treatment catalyst (12), urea, and NOx contained in the exhaust gas, and HC adsorbed on the HC treatment catalyst 12 are reacted with each other to form intermediate products having cyano groups, oximes, and amino groups, and these intermediate products are sent to the NOx selective reducing catalyst (14).
361 citations
Patent•
19 Jul 1993TL;DR: In this paper, an NOx absorbent (6, 6A) is installed in an exhaust conduit of an internal combustion engine capable of fuel combustion at lean air-fuel ratios.
Abstract: An NOx absorbent (6, 6A) is installed in an exhaust conduit (4) of an internal combustion engine (2) capable of fuel combustion at lean air-fuel ratios. An oxygen concentration is repeatedly or continuously decreased by, for example, switching the air-fuel from the lean air-fuel ratio to a stoichiometric or rich air fuel ratio when the exhaust gas temperature is higher than 550°C or when NOx absorbent temperature is higher than 500°C. As a result, the SOx absorbed in the NOx absorbent (6, 6A) during lean air-fuel ratio, low temperature operation is released from the NOx absorbent (6, 6A), and the SOx-poisoned NOx absorbent is recovered.
253 citations
Patent•
10 May 1995TL;DR: In this article, the adsorption state of nitrogen oxide adsorbed by the catalytic device is estimated by an electronic control unit during the lean-combustion driving of the engine.
Abstract: In a control apparatus and control method for an internal combustion engine having an exhaust purifying catalytic device for adsorbing nitrogen oxide contained in exhaust gases from the engine, the adsorption state of nitrogen oxide adsorbed by the catalytic device is estimated by an electronic control unit during the lean-combustion driving of the engine. If the catalytic device is saturated with nitrogen oxide, the ignition timing is delayed and the exhaust gas is recirculated to the intake side of the engine with the lean air-fuel ratio kept unchanged. This starts the nitrogen oxide reduced driving mode for deteriorating the combustion state in the engine. At this time, the engine output will not change by a great amount. Further, a reducing atmosphere is created around the catalytic device by unburnt gases, generated due to the deterioration of the combustion state, to deoxidize the adsorbed nitrogen oxide. As a result, the purifying ability of the catalytic device can be recovered to suppress the discharge amount of nitrogen oxide without deteriorating the smoothness of engine driving and fuel economy.
248 citations
Patent•
14 Nov 1994TL;DR: In this paper, the authors provided an exhaust gas purification device for an engine having an exhaust passage, the device comprising a catalyst arranged in the exhaust passage and having an upstream end and a downstream end, a purification ratio of exhaust gas by the catalyst becoming more than a predetermined ratio when a temperature of the catalyst is within a predetermined temperature range.
Abstract: According to the present invention, there is provided an exhaust gas purification device for an engine having an exhaust passage, the device comprising a catalyst arranged in the exhaust passage and having an upstream end and a downstream end, a purification ratio of exhaust gas by the catalyst becoming more than a predetermined ratio when a temperature of the catalyst is within a predetermined temperature range, cooling means for cooling the upstream end of the catalyst, heating means for heating the downstream end of the catalyst, and control means for controlling the cooling means and the heating means to maintain the temperature of a portion of the catalyst, which portion is positioned between the upstream end and the downstream end, in the predetermined temperature range.
240 citations