568 results about "Lean burn" patented technology

A system for effective NOx and particulate matter control in a diesel or other lean burn internal combustion engine is presented. The system includes a urea-based SCR catalyst having an oxidation catalyst coupled upstream of it and a particulate filter coupled downstream of the SCR catalyst. This system configuration results in improved NOx conversion due to fast SCR catalyst warm-up and higher operating temperatures. Additionally, placing the particulate filter last in this system configuration reduces tailpipe ammonia emissions as well as prevents any thermal damage to the SCR catalyst due to the particulate filter regeneration.

Provided is an emissions treatment system for an exhaust stream, having a NOx storage reduction (NSR) catalyst with a NOx sorbent at a concentration of at least 0.1 g/in³ and a platinum group metal component dispersed on a refractory metal oxide support; and, an SCR catalyst disposed downstream of the NSR catalyst. The emissions treatment system is advantageously used for the treatment of exhaust streams from diesel engines and lean burn gasoline engines.

A diesel engine (1) provided with a NOx catalyst (28A) and a diesel particulate filter (28B) performs lean burn operation during normal running, rich burn operation during regeneration of the NOx catalyst (28A), operation under the stoichiometric air-fuel ratio during desulphating of the NOx catalyst (28A), and operation under a slightly lean air-fuel ratio to regenerate the filter after desulphating of the NOx catalyst (28A). When the lean burn operation is applied, a controller (31) first controls the fuel injection amount, and controls an air supply amount based on the fuel injection amount. When rich burn operation is applied, the controller (31) first controls the air supply amount and controls the fuel injection amount based on the air supply amount. Due to this control, the response of the excess air factor control is enhanced while preventing torque fluctuation accompanying the variation of the target excess air factor.

Method and device for reduction of a gas component in an exhaust gas flow of a combustion engine (1) that is adapted for operation by a lean air/fuel mixture. An exhaust pipe (21) is included for transport of the exhaust gas flow from the engine (1). A separation unit (22) is also included that is arranged along the exhaust pipe (21), which separation unit (22) has a wall structure (32) of a material which provides separation of the gas component from the exhaust gas flow by means of a selective passage of the gas component before other gas components in the exhaust gas flow. The method provides for a reduction and a separation unit that is intended to be utilized during such a reduction. An improved reduction of in particular NO_x compounds from a so-called “lean-burn” engine is also provided.

A burner for use in the emissions system of a lean burn internal combustion engine. The burner has a special burner head that enhances atomization of the burner fuel. Its combustion chamber is designed to be submersed in the engine exhaust line so that engine exhaust flows over the outer surface of the combustion chamber, thereby providing efficient heat transfer.

An exhaust system for an internal combustion engine has a catalysed ceramic wall flow particulate filter coated with a washcoat composition. The washcoat composition includes an oxidation catalyst of at least one platinum group metal and a NO_x absorbent. The washcoat composition has a D50 of less than or equal to 8 μm. The NO_x absorbent absorbs NO_x contained in an exhaust gas when the composition of the exhaust gas is lambda >1, and releases the NO_x absorbed in the NO_x absorbent when the exhaust gas composition is 1≦lambda. The exhaust system has a platinum group metal catalyst upstream of the filter for oxidising NO to NO₂ at least when the composition of the exhaust gas is lambda >1. The uncoated portions of the ceramic wall flow particulate filter have a porosity of >40% and a mean pore size of 8-25 μm.

A catalyst system to provide emission reductions under lean and stoichiometric conditions. The catalyst system comprises a forward catalyst having a first cerium-free zone including oxides of aluminum, alkali metals and alkaline earth metals and precious metals and a second zone with a lower loading of precious metals, oxides of aluminum, alkali metals or alkaline earth metals. This forward catalyst stores NOx emissions under lean conditions for subsequent reduction and converts HC, CO and NOx during stoichiometric operation. The second downstream catalyst includes precious metals, reduces emissions under stoichiometric conditions, and stores any residual NOx emitted from the first catalyst for subsequent reduction. In another embodiment, a forward catalyst has top and bottom layers designed to reduce emissions under lean conditions. In this embodiment, a second downstream catalyst is used to reduce emissions under stoichiometric conditions. In yet another catalyst, multiple zones are created within a single catalyst.

An exhaust system (10) for a lean-burn internal combustion engine comprises a nitrogen oxide (NO_x) absorbent (28), a catalyst (30) for catalyzing the selective catalytic reduction (SCR) of a NO_x with a NO_x specific reactant, first means (18, 22) for introducing a NO_x specific reactant or a precursor thereof into an exhaust gas upstream of the SCR catalyst (30) and means (24) for controlling the introduction of the NO_x-specific reactant or precursor thereof into the exhaust gas via the first introducing means (18, 22), wherein the SCR catalyst (30) is disposed upstream of the NO_x absorbent (28) and optionally with the NO_x absorbent, wherein the control means (24) is arranged to introduce the NO_x-specific reactant or the precursor thereof to exhaust gas via the first introducing means (18, 22) only when the SCR catalyst (30) is active, whereby exhaustion of NO_x-specific reactant to atmosphere is substantially prevented.

The present invention is an aftertreatment system for lean burn internal combustion engines. The present invention provides a multiple branch lean NOx trap, or LNT, with a diverter valve operable to selectively direct lean exhaust flow to one portion of the LNT while another portion of the LNT regenerates in a low oxygen environment. Additionally, the present invention employees a continuously operating side stream exhaust fuel reformer that delivers a reductant, such as partially oxidized (POx) gas or reformate, to the LNT for regeneration. The present invention also provides a method of exhaust aftertreatment of a lean burn internal combustion engine utilizing the system provided.

An exhaust system 20 for an internal combustion engine comprises a) a first catalysed substrate monolith 12 comprising a first washcoat coating disposed in a first washcoat zone 16 of the substrate monolith and a second washcoat coating disposed in a second washcoat zone 18 of the substrate monolith, wherein the first washcoat coating comprises a catalyst composition comprising at least one platinum group metal (PGM) and at least one support material, wherein at least one PGM in the first washcoat coating is liable to volatilise when the first washcoat coating is exposed to relatively extreme conditions including relatively high temperatures, wherein the second washcoat coating comprises at least one material supporting copper for trapping volatilised PGM and wherein the second washcoat coating is oriented to contact exhaust gas that has contacted the first washcoat; and b) a second catalysed substrate monolith 14 comprising a catalyst for selectively catalysing the reduction of oxides of nitrogen to dinitrogen with a nitrogenous reductant disposed downstream from the first catalysed substrate monolith.

The invention provides devices and methods for generating H₂ and CO in an O₂ containing gas stream. The invention also provides devices and methods for removal of NO_X from an O₂ containing gas stream, particularly the oxygen-rich exhaust stream from a lean-burning engine, such as a diesel engine. The invention includes a fuel processor that efficiently converts added hydrocarbon fuel to a reducing mixture of H₂ and CO. The added fuel may be a portion of the onboard fuel on a vehicle. The H₂ and CO are incorporated into the exhaust stream and reacted over a selective lean NO_X catalyst to convert NO_X to N₂. thereby providing an efficient means of NO_X emission control.

Catalysts, systems, and methods disclosed herein provide for reduced NO_x emissions in the exhaust stream of a lean burning engine. The catalysts include two different types of selective catalytic reduction (SCR) catalysts (i.e., two different types of catalysts that may catalytically reduce NO_x using a reductant). The first SCR catalyst (116) is an SCR catalyst having a composition that produces a reductant (e.g., an HC-SCR catalyst that produces ammonia) and the second catalyst (118) is an SCR catalyst (e.g., NH₃-SCR) having a composition that reduces NO_x using the reductant produced by the first SCR catalyst (116).

A method is disclosed for controlling operation of an engine coupled to an exhaust treatment catalyst. Under predetermined conditions, the method operates an engine with a first group of cylinders combusting a lean air/fuel mixture and a second group of cylinders pumping air only (i.e., without fuel injection). In addition, the engine control method also provides the following features in combination with the above-described split air/lean mode: idle speed control, sensor diagnostics, air/fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, default operation, and exhaust gas and emission control device temperature control. In addition, the engine control method also changes to combusting in all cylinders under preselected operating conditions such as fuel vapor purging, manifold vacuum control, and purging of stored oxidants in an emission control device.

A variety of methods and arrangements for controlling the exhaust gas temperature of a lean burn, skip fire controlled internal combustion engine are described. In one aspect, an engine controller includes an aftertreatment system monitor and a firing timing determination unit. The aftertreatment monitor obtains data relating to a temperature of one or more aftertreatment elements, such as a catalytic converter. Based at least partly on this data, the firing timing determination unit generates a firing sequence for operating the engine in a skip fire manner such that the temperature of the aftertreatment element is controlled within its effective operating range.