Showing papers on "Lean burn published in 2001"

Dynamic Optimization of Lean Burn Engine Aftertreatment

Abstract: The competition to deliver fuel e cient and environmentally friendly vehicles is driving the 1 2 Submitted to Journal of Dynamics Systems, Measurement, & Control automotive industry to consider ever more complex powertrain systems. Adequate performance of these new highly interactive systems can no longer be obtained through traditional approaches, which are intensive in hardware use and nal control software calibration. This paper explores the use of Dynamic Programming to make model-based design decisions for a lean burn, direct injection spark ignition engine, in combination with a three way catalyst and an additional threeway catalyst, often referred to as a lean NOx trap. The primary contribution is the development of a very rapid method to evaluate the tradeo s in fuel economy and emissions for this novel powertrain system, as a function of design parameters and controller structure, over a standard emission test cycle.

Characterization and performance of Pt-USY in the SCR of NOx with hydrocarbons under lean-burn conditions

Abstract: Pt-USY was used for the selective catalytic reduction of NOx with hydrocarbons in the presence of excess oxygen. The catalyst was prepared by an ion-exchange method and characterized by XRD, TEM, CO chemisorption, and Ar adsorption at 87 K. The platinum particle size distribution was found to be broad (2–20 nm), with no apparent sintering of the active phase during the HC-SCR process after 25 h time-on-stream. Generally, large metal clusters (>15 nm) are situated at the external surface of the zeolite, while the smaller ones are located in the pores of the support. Pt-USY shows an excellent activity in the deNOx reaction (molar NOx conversion 90% at 475 K) with propene as the reductant in 5 kPa O2, as well as stable operation during time-on-stream. Propane only yields a low NOx conversion compared to propene. The presence of high oxygen contents (5–10 kPa O2) slightly inhibits the reaction. No significant decrease in deNOx activity was observed at high space velocities (up to 100,000 h−1). The presence of SO2 and H2O in the feed stream did not significantly affect the deNOx activity. Pt-USY performs better under lean-burn conditions than other Pt-catalysts supported on e.g. ZSM-5, Al2O3, or SiO2. The selectivity to N2 was similar to the other Pt-based catalysts (∼30%), the other major product being N2O.

Method and apparatus for enhancing fuel economy of a lean-burn internal combustion engine

Abstract: A method and apparatus for controlling the operation of a "lean-burn" internal combustion engine (12) in co-operation with an exhaust gas purification system having an emissions control device (34,36) capable of alternatively storing and releasing NO x when exposed to exhaust gases that are lean and rich of stoichiometry, respectively, optimises vehicle fuel economy while complying with emissions standards by prohibiting lean engine operation only when tailpipe emissions, calculated in terms of grams of an exhaust gas constituent per vehicle mile travelled, exceeds a permissible threshold value. The threshold value is preferably itself periodically determined based upon a detected or determined level of vehicle activity, such that vehicle activity characterised by greater transient engine operation prescribes a relatively lower level of permissible vehicle emissions.

Sox tolerant nox trap catalysts and methods of making and using the same

Abstract: The present invention relates to sulfur tolerant catalyst composites useful for reducing contaminants in exhaust gas streams, especially gaseous streams containing sulfur oxide contaminants. More specifically, the present invention is concerned with improved NOx trap catalysts for use in diesel engines as well as lean burn gasoline engines. The sulfur tolerant NOx trap catalyst composites comprise a platinum component, a support, a NOx sorbent component, and a spinal material prepared by calcining an anionic clay material represented by the formula MmNn(OH)(2m+2n)Aa.bH2O, wherein the formula is defined herein. The sulfur tolerant NOx trap catalyst composites are highly effective with a sulfur containing fuel by trapping sulfur oxide contaminants which tend to poison conventional NOx trap catalysts used to abate other pollutants in the stream. The sulfur tolerant NOx trap catalyst composites are suitable for diesel engines because the composites can be regenerated at moderate temperatures with rich pulses, rather than at high temperatures.

Piloted rich-catalytic lean-burn hybrid combustor

Abstract: A catalytic combustor assembly (3) which includes, an air source (8), a fuel delivery means (12), a catalytic reactor assembly (20), a mixing chamber (44), and a means for igniting a fuel/air mixture (40). The catalytic reactor assembly (20) is in fluid communication with the air source (8) and fuel delivery means (12) and has a fuel/air plenum (38) which is coated with a catalytic material. The fuel/air plenum (38) has cooling air conduits (30) passing therethrough which have an upstream end (46). The upstream end (46) of the cooling conduits (30) is in fluid communication with the air source (8) but not the fuel delivery means (12).

Method and system for reducing NOx tailpipe emissions of a lean-burn internal combustion engine

Abstract: A method and apparatus for operating a lean-burn internal combustion engine in cooperation with an exhaust gas purification system having a three-way catalyst and a NO x trap located downstream of the three-way catalyst includes a controller which calculates current levels of tailpipe NO x during lean engine operating conditions based upon the difference between a determined instantaneous feedgas NO x concentration and a determined instantaneous trap efficiency. The controller discontinues lean engine operation when the tailpipe NO x , expressed in terms of either grams-per-mile or grams-per-hour, exceeds a predetermined threshold level, either instantaneously or as averaged over the course of a trap purge-fill cycle.

Controlled auto-ignition lean burn stratified engine by intelligent injection

Abstract: A system and method for widening auto-ignition range of a lean burn internal combustion engine employs stratified charge of exhaust gas content and air content. A fuel injection system carries out a first injection of gasoline fuel for dispersion within the air content, and a second injection of gasoline fuel for dispersion within the exhaust gas content. This intelligent injection of gasoline fuel accomplishes auto-ignition of gasoline fuel within the exhaust gas content over extended range of engine speed and load.

Catalyst for purifying exhaust gases

Abstract: A catalyst for purification of exhaust gases including (1) a catalysis-promoting coating comprising a noble metal catalyst and a NOx storage component loaded onto a carrier material, wherein the NOx storage component comprises an alkali metal and, (2) a ceramic substrate for supporting the catalysis-promoting coating, wherein the ceramic substrate exhibits resistance to alkali metal migration below 1000°C and a coefficient of thermal expansion of less than about 25x10-7/°C (25-800°C). A second aspect of the invention is a process for purifying an exhaust gas from a lean burn engine involving simultaneously removing carbon monoxide, hydrocarbons and nitrogen oxides by bringing the exhaust gas from a lean burn engine into contact with the exhaust gas purifying catalyst of the present invention disclosed above. In this process a majority of the nitrogen oxides in the exhaust gas are adsorbed to the NOx storage component on the porous support under a lean burn atmosphere in which oxidizing concentrations are above a stoichiometric point that is required for oxidizing components to be oxidized in the exhaust gas. Furthermore, when the exhaust gas is temporarily change from lean burn to fuel-rich, the adsorbed nitrogen oxides are released and chemically reduced by a reaction with the hydrocarbons and carbon monoxide in the exhaust gas under a stoichiometric atmosphere or a fuel-rich atmosphere in which oxygen concentrations are below stoichiometric point.

Experimental and Computational Study of Trapped Vortex Combustor Sector Rig with High-Speed Diffuser Flow

Abstract: The Trapped Vortex Combustor (TVC) potentially offers numerous operational advantages over current production gas turbine engine combustors. These include lower weight, lower pollutant emissions, effective flame stabilization, high combustion efficiency, excellent high altitude relight capability, and operation in the lean burn or RQL modes of combustion. The present work describes the operational principles of the TVC, and extends diffuser velocities toward choked flow and provides system performance data. Performance data include EINOx results for various fuel-air ratios and combustor residence times, combustion efficiency as a function of combustor residence time, and combustor lean blow-out (LBO) performance. Computational fluid dynamics (CFD) simulations using liquid spray droplet evaporation and combustion modeling are performed and related to flow structures observed in photographs of the combustor. The CFD results are used to understand the aerodynamics and combustion features under different fueling conditions. Performance data acquired to date are favorable compared to conventional gas turbine combustors. Further testing over a wider range of fuel-air ratios, fuel flow splits, and pressure ratios is in progress to explore the TVC performance. In addition, alternate configurations for the upstream pressure feed, including bi-pass diffusion schemes, as well as variations on the fuel injection patterns, are currently in test and evaluation phases.

Apparatus for detecting concentration of vapor fuel in lean-burn internal combustion engine, and applied apparatus thereof

Abstract: An apparatus for detecting a concentration of a vapor fuel in a lean-burn internal combustion engine includes a module for performing purge concentration learning when in a lean-burn where an air/fuel ratio sensor does not sufficiently work. When detecting the concentration of the vapor fuel during a lean-burn operation of the internal combustion engine, the internal combustion engine is switched over to a homogeneous combustion operation from a lean-burn operation, and the concentration of the vapor fuel is detected under the homogeneous combustion operation. Alternatively, the combustion is switched over to the homogeneous combustion when in a rich spike and when ensuring a brake negative pressure, and hence the concentration of the vapor fuel is detected by utilizing this timing. The thus detected and learned concentration of the vapor fuel is utilized for the purge control when in the lean-burn.

Gasoline direct-injection engine

Abstract: In a gasoline direct injection engine, the sloping surface formed on the top of the piston and the opposing roof surface of the cylinder head form mutually different angles with respect to a plane perpendicular to a cylinder axial line so that the intake air caught between the sloping surfaces of the piston and the opposing roof surface is gradually squeezed out of the gap between them, and is prevented from directly flowing into the recess at high speed. As a result, the mixture in the recess is kept at a favorable air/fuel ratio and the engine is enabled to operate in a stratified charge lean burn mode over a wide operating range.

Fuel injection system for internal combustion engine

Abstract: In a multi-port fuel injection system for a lean burn engine, the attaching of fuel particles from the fuel spray onto a wall surface, which is a problem in atomizing injected fuel, is reduced, and the quality and shape of the mixed gas in the cylinders of the engine is improved. The engine has a fuel injector 1 ; an intake valve 6 for opening and closing an intake port; and an intake air flow control device 10 . The injected fuel is shaped to provide a low penetration fuel spray when the engine is operated in a low load state and at a low rotation speed, and the injected fuel is shaped to provide a high penetration fuel spray when the engine is operated in a high load state and at a high rotation speed. The fuel is injected in synchronism with the intake stroke of the engine, and it is transported by the air flow flowing through the intake air flow control device 10 to suppress the attaching of fuel particles from the fuel spray onto a wall surface of the intake manifold.

Emissions and fuel consumption of natural gas powered city buses versus diesel buses in real-city traffic

Abstract: In the fkame of the IEA-AMF project "Real Impact of New Technologies for Heavy Duty Vehicles", three state-of-the-art city bus technologies were evaluated for fuel consumption and emissions in real city traffic and in a number of test cycles, both on engine and on vehicle level. The three buses were a diesel bus, a natural gas bus with stoichiometric fuel control and three-way catalyst, and a natural gas bus with lean bum fuel control. The paper will compare fuel consumption and emissions of the three buses measured in real-city traffic using Vito's VOEM measurement system. The measurements showed that the natural gas buses had clearly higher fuel consumption (in diesel equivalents) than the diesel bus, caused by the lower average engine efficiency. Concerning the emissions, the natural gas bus with stoichiometric fuel control totally fulfilled its expectations with about 10 times lower NO,, THC and CO emissions than the diesel bus. The natural gas bus with lean burn fuel control had low CO emissions, but rather high THC and NO, emissions. In order to lower NO, emissions, the lambda control system needed some adjustments. The buses were tested with three different loads. Vehicle weight had a clear impact on fuel consumption and CO2 emissions for the three buses. Considering the other emissions, only NO, emissions of the diesel bus clearly related to vehicle weight. The actual function of a bus is to transport passengers from one point to another, so it is justified to relate fuel consumption and emissions to the number of passengers. This allows a comparison with other vehicles like passenger cars, vans or minibuses.

Fuel injection method of internal combustion engine and fuel injection apparatus of internal combustion engine

Abstract: In a fuel injection apparatus of an internal combustion engine comprising a fuel injector, an intake valve device for opening and closing an intake port, and an intake air flow control device arranged in an upstream side of the intake valve device, a fuel injection is synchronized with an intake stroke of the engine. A fuel spray is oriented to an inner wall face which is positioned in an opposite side to an inner wall face of a cylinder heads in a fuel injector side and the fuel spray is transported by an air flow having a strong fluidization which is entered from the intake air control device. In a port injection lean burn engine, an adhesion to the wall face according to the fuel spray can be reduced, and a quality and a formation state of an air-fuel mixture in a cylinder can be improved.

Method and system for transitioning between lean and stoichiometric operation of a lean-burn engine

Abstract: An exhaust treatment system for an internal combustion engine includes a catalytic emission control device. When transitioning the engine between a lean operating condition and a stoichiometric operating condition, as when scheduling a purge of the downstream device to thereby release an amount of a selected exhaust gas constituent, such as NO x , that has been stored in the downstream device during the lean operating condition, the air-fuel ratio of the air-fuel mixture supplied to each cylinder is sequentially stepped from an air-fuel ratio of at least about 18 to the stoichiometric air-fuel ratio. The purge event is preferably commenced when all but one cylinders has been stepped to stoichiometric operation, with the air-fuel mixture supplied to the last cylinder being stepped immediately to an air-fuel ratio rich of a stoichiometric air-fuel ratio.

A combustion chamber

Abstract: A three stage lean burn combustion chamber (28) comprises a primary combustion zone (36), a secondary combustion zone (40) and a tertiary combustion zone (44). Each of the combustion zones (36,40,44) is supplied with premixed fuel and air by respective fuel and air mixing ducts (76,78,80,92). Secondary fuel injectors (106) and two secondary fuel manifolds (105A, 105B) supply fuel into different circumferential sectors, halves, of the secondary fuel and air mixing duct (80). The secondary fuel manifolds (105A, 105B) have secondary fuel valves (107A,107B) which supply a greater proportion of fuel to the secondary fuel manifold (105A) than the secondary fuel manifold (105B) so that there is circumferential biasing of fuel in the secondary combustion zone (40). This circumferential biasing of fuel in the secondary combustion zone (40) reduces the generation of harmful pressure oscillations in the combustion chamber (28). Alternatively the biasing of the fuel may be in the primary or tertiary combustion zones (36,44).

Drive power control apparatus and method for vehicle

Abstract: An engine output for bringing the drive power of a motor vehicle to a requested value is determined as a target output. One of the lean burn and the stoichiometric burn is selected as a combustion form that achieves a best fuel consumption performance in terms of the control of the actual engine output to the target output. That is, an output value that serves as a criterion for determining whether to switch the combustion force is determined based on the minimum fuel consumption rate during the stoichiometric-burn operation and the minimum fuel consumption rate during the lean-burn operation in which the fuel consumption involved in the rich spike control is taken into account. If the target output is less than the output value, the lean-burn operation is performed. If the target output is greater than the output value, the stoichiometric-burn operation is performed.

Method and apparatus for measuring lean-burn engine emissions

Abstract: A method and apparatus for controlling the operation of a "lean-burn" internal combustion engine (12) in co-operation with an exhaust gas purification system having an emissions control device (36) capable of alternatively storing and releasing NO x when exposed to exhaust gases that are lean and rich of stoichiometry, respectively, optimises vehicle fuel economy while complying with emissions standards by prohibiting lean engine operation only when tailpipe emissions, calculated in terms of grams of an exhaust gas constituent per vehicle mile travelled, exceeds a permissible threshold value. The threshold value is preferably itself periodically determined based upon a detected or determined level of vehicle activity, such that vehicle activity characterised by greater transient engine operation prescribes a relatively lower level of permissible vehicle emissions.

Investigation of Co-Based DeNOx Catalysts for the Treatment of Natural Gas Lean-Burn Engine Exhaust

Abstract: The catalytic reduction of nitric oxide with methane in lean conditions has been investigated on cobalt-based powder and monolith catalysts such as Co-exchanged ferrierite, Co-exchanged beta zeolite and Co–ZrO2. From catalyst laboratory testing the following activity scale was obtained: Co-ferrierite > Co-beta >>> Co–ZrO2, suggesting a significant role of the support catalytic matrix. In the tests at the engine exhaust, the best results were obtained with Co-ferrierite, after water separation from the exhaust. However, in the presence of the high concentration of water, typical of the engine exhaust, the performances were dramatically reduced.

High efficiency compression ignition aftertreatment devices for combined use of lean-burn combustion systems and three-way catalysts

Abstract: A high efficiency compression ignition after-treatment system of a combustion engine includes a first combustion chamber adapted to reciprocatably receive a first piston assembly and a second combustion chamber adapted to reciprocatably receive a second piston assembly. A combustion exhaust passage is coupled between the first and the second combustion chambers. A fuel passage may be connected to the first combustion chamber, and a fuel passage connected to the second combustion chamber. A processed exhaust passage is coupled to the second combustion chamber for receiving the processed exhaust therethrough. A fuel injector is coupled to the second combustion chamber. A three-way catalyst has an inlet coupled to the processed exhaust passage and an outlet coupled to an exhaust passage. An exhaust gas oxygen sensor is connected to the processed exhaust passage. A fuel controller is coupled to the fuel injector and the exhaust gas oxygen sensor.

Exhaust emission control device for an internal combustion engine

Abstract: The present invention is provided with an NOx catalyst 17 provided in the exhaust passage of an internal combustion engine capable of lean burn and adapted to release and reduce absorbed NOx by a reducing agent, a reducing agent supplying means 19 provided in the exhaust passage on the upstream side of the NOx catalyst 17, a load detecting means for detecting the load of an internal combustion engine 1, and a reducing agent addition control means for controlling the reducing agent addition period and the reducing agent addition interval on the basis of the load of the internal combustion engine 1. The addition period and the addition interval for the reducing agent are controlled taking into account, for example, the degree to which reducing agent adheres to the wall surface in the exhaust passage depending on the velocity, temperature, etc., of the exhaust of the internal combustion engine 1, whereby a sufficient amount of reducing agent is supplied to the NOx catalyst side independently of the operating condition. Thus, even if the operating condition of the internal combustion engine is changed, it is always possible to supply an appropriate amount of reducing agent to the NOx catalyst.

Emission control method and apparatus of an internal combustion engine

Abstract: A method and apparatus control an emission of an internal combustion engine. The emission control of the internal combustion engine has a three-way catalyst and a NOx storage-reduction catalyst in an exhaust passage. The emission control reduces NOx stored in the catalyst to recover its NOx storing capability by performing a rich spike control during a lean burn operation. The emission control apparatus has an electronic control unit that limits the execution time of the rich spike control and, after the elapse of the limited execution time, performs a stoichiometric burn operation. The emission control prevents prolongation of the rich spike control and thereby prevents deterioration of HC and CO emissions. By performing the stoichiometric burn operation after the elapse of the limited time of the rich spike control, the emission control apparatus recovers the NOx storing capability while avoiding deterioration of HC and CO emissions.