Showing papers on "Lean burn published in 1995"

Hydrogen enriched natural gas as a motor fuel with variable air fuel ratio and fuel mixture ratio control

Abstract: A hydrogen and natural gas fuel mixture for internal combustion engines is provided for vehicle engines such as those used in standard production engines for automobiles, trains and lawn mowers The gaseous fuel for operating a vehicle combustion engines includes approximately 21 to 50% Hydrogen and the rest natural gas constituents such as combinations of Methane, Carbon Dioxide, Nitrogen, Ethane, Propane, Iso-Butane, N-Butane, Iso Pentane, N-Pentane, and Hexanes Plus A fuel mixture of approximately 28 to 36 percent Hydrogen and a air fuel equivalence ratio of approximately 0625 is an extreme lean burn condition that yields hydrocarbon emission levels of less than approximately 104 ppm (084 hm/hp hr) Current internal combustion engines that are in mass production can take this alternative fuel without any substantial modifications to their systems This alternative fuel is lean burning and emits emissions that are below current legal standards The novel fuel mixture can be used in internal combustion engines for automobiles, lawnmowers, and trains A control system for allowing the internal combustion engines to operate at extreme lean burn conditions is also provided for use with both a carburetor and fuel injection system For a carburetor system, a secondary demand regulator system can kick in when a throttle is wide open and will allow additional fuel to pass through the system to meet instantaneous power demands such that occur when full throttle depression is insufficient for severe grade climbing, expressway merging, passing and the like The fuel injection system can also be programed with a control algorithm that will select air fuel ratios The computer control can increase fuel with respect to air when the throttle reaches a selected point of travel The computer control can also dynamically change the hydrogen and natural gas fuel mixture ratio dynamically while the vehicle is being operated based on engine power demands and emissions

Lean-burn nox catalyst/nox trap system

Abstract: The invention is a catalyst system for purifying exhaust gases generated by a lean-burn internal combustion engine, particularly automotive engines. The catalyst system comprises two separate components located in the exhaust gas passage, the first being a lean-burn nitrogen oxide catalyst and the second being a nitrogen oxide trap material, where the lean-burn NOx catalyst is located upstream of the NOx trap material in the exhaust gas passage. Preferably the catalyst comprises a transition metal such as copper, chromium, iron, cobalt, or manganese loaded on a refractory oxide or exchanged into a zeolite. The NOx trap preferably comprises (i) at least one precious metal selected from platinum and palladium loaded on a porous support; and (ii) at least one alkali metal or alkaline earth metal (a) loaded on a porous support or (b) present as an oxide thereof. Optionally the catalyst system may further comprise a three-way catalyst located either between the two-components or after the NO x trap material.

Output torque control apparatus and method for an internal combustion engine

Abstract: The invention provides an output torque control method and apparatus for a lean burn internal combustion engine which accounts for aging of component parts, and in which no stepwise change of torque or shock occur when an air fuel ratio is changed. The method and apparatus according to the invention control an intake air amount while maintaining an emission purification function by controlling the air fuel ratio to that of a theoretical mixture (air fuel ratio of 14.7) in a case where a limit NOx emission is determined by using a detected air fuel ratio and lean burn operation becomes difficult due to the amount of NOx emissions. Abrupt change of an output torque when the air fuel ratio is changed is curtailed by controlling a fuel amount or an air amount after calculating the fuel amount or the air amount from an engine speed and an accelerator depression angle.

Compression ignition type gasoline engine injecting fuel inside intake port during exhaust stroke

Abstract: There is provided a compression ignition type gasoline engine operable under a stable lean burn condition with a high compression ratio, and which has a simple construction without using a pre-heating system for an air-fuel mixture. An intake port communicates with a combustion chamber via an opening. The opening is closed by an intake valve. A fuel injection valve is provided in the intake port so as to inject an amount of gasoline inside the intake port within a duration in which the opening is substantially closed by the intake valve. Heat is generated in the mixture in the combustion chamber by means of a high compression ratio so that the mixture is self-ignited only by heat generated by compression. The compression ratio ranges from about 14 to about 20.

Method of purifying exhaust gas from internal combustion engine

Abstract: This method comprises bringing exhaust gas from an internal combustion engine, which is operated at a fuel-lean air/fuel ratio, in contact with an iridium-containing catalyst in a first zone and then in contact with a platinum-containing catalyst in a second zone situated downstream of the first zone. This method is effective for exhaust gas from lean burn engines over a wide temperature range of 200 to 500°C, produces less N2O in a low-temperature range of 200 to 300°C, and can purify exhaust gas stably and effectively even at a high temperature of 700°C or over.

Diluents and Lean Mixture Combustion Modeling for SI Engines with a Quasi-Dimensional Model

Abstract: Lean mixture combustion might be an important feature in the next generation of SI engines, while diluents have already played a key role in the reductions of emissions and fuel consumption. Lean burning modeling is even more important for engine modeling tools which are sometimes used for new engine development. The effect of flame strain on flame speed is believed to be significant, especially under lean mixture conditions. Current quasi-dimensional engine models usually do not include flame strain effects and tend to predict burn rate which is too high under lean burn conditions. An attempt was made to model flame strain effects in quasi-dimensional SI engine models. The Ford model GESIM was used as the platform. A new strain rate model was developed with the Lewis number effect included. A 2.5L V6 4-valve engine and 4.6L V8 2-valve modular engine were used to validate the modified turbulent entrainment combustion model in GESIM. Results showed that the current GESIM can differ by as much as 10 crank angle degrees compared with test data. The modified GESIM can predict burn duration to within 1--2 CA of experimental data, which is considered very good for engine models.

Lean burn engine for automobile

Abstract: A lean burn engine adapted to establish a specified air-fuel ratio leaner by predetermined rate than a stoichiometric air-fuel ratio in a range of low engine speeds and low engine loads is provided with an air intake system of a low speed type which provides a high charging efficiency in a range of low engine speeds and an exhaust system capable of eliminating a nitrogen oxide emission in the exhaust even during lean burning.

Lean Burn Natural Gas Fueled S.I.Engine and Exhaust Emissions

Abstract: An experimental study was undertaken to study exhaust emission from a lean-burn natural gas spark ignition engine. The possibility that such an engine may help to reduce exhaust emissions substantially by taking advantage of natural gas fuel properties, such as its antiknock properties and extended lean flammability limit compared to gasoline, was the main motivation behind the investigation. A four cylinder, automotive type spark ignition engine was used in the investigation. The engine was converted to operate on natural gas by replacing its fuel system with a gaseous carburetion system. A 3-way metal metrix catalytic converter was used in the engine exhaust system to reduce emission levels. The engine operated satisfactorily at an equivalence ratio as lean as 0.6, at all speeds and loads. As a result NOx emissions were significantly reduced. However, hydrocarbon emissions were high, particularly at very lean conditions and light loads. Most of these hydrocarbons were made up of methane with small concentrations of ethane and propane. Coefficient of variations in hydrocarbons were generally high at very lean operating conditions and light loads, but decreased with increasing equivalence ratio and engine speed. Methane concentrations in the engine exhaust decreased with increasing load and equivalence ratio. Atmore » lean air-to-fuel ratios and light loads oxidation of methane in the catalyst was substantially limited and no NOx reduction was achieved. In addition, the proportion of nitric oxide in oxides of nitrogen increased with increasing amount of NOx in the engine exhaust. A major problem encountered in the study was the inability of the fuel system to maintain near constant air-to-fuel ratios at steady operating conditions.« less

Catalyst for purifying exhaust gas from lean burn engine and method for purification

Abstract: A catalyst for the purification of an exhaust gas emitting from a lean burn engine using gasoline as a fuel thereof and a method for the purification are provided. The catalyst has deposited on an inert carrier a mixture of a catalytically active component comprising palladium, an oxide of at least one alkali metal selected from the group consisting of potassium, sodium, rubidium, and cesium, and an oxide of at least one iron family metal selected from the group consisting of cobalt, nickel, and iron with a refractory inorganic oxide. This catalyst is used either alone or in combination with an oxidizing catalyst or a three-way catalyst for the purification of the exhaust gas from the lean burn engine using gasoline as a fuel thereof.

Control for catalyst in exhaust system of IC engine

Abstract: The IC engine has a catalyst (13) in the exhaust system as well as a sensing system for exhaust quality. When the engine is operating in lean burn the catalyst eventually becomes saturated with nitrous oxide. This saturation is detected and a recycling of part of the exhaust gasses into the inlet manifold produces a slight reduction in the burn providing some unburnt gasses in the exhaust. This enables the adsorbed nitrous oxide to be oxidised and disposed off safely. Two levels of saturation detectors are provided. The level of recycling is such as not to affect the fuel efficiency unduly an does not affect the motor running characteristics greatly. No change in the airflow intake, throttle setting etc. are required.

Comparative Emissions from Natural Gas and Diesel Buses

Abstract: Data has been gathered using the West Virginia University Heavy Duty Transportable Emissions Laboratories from buses operating on diesel and a variety of alternate fuels in the field. Emissions data are acquired from buses using the Central Business District cycle reported in SAE Standard J1376; this cycle has 14 ramps with 20 mph (32.2 km/h) peaks, separated by idle periods. During the three years of testing, a significant fraction of emissions data was acquired from buses with Cummins L-10 engines designed to operate on either CNG or diesel. The CNG lean burn engines were spark ignited and throttled. Early CNG engines, which were pre-certification demonstration models, have provided the bulk of the data, but data from 9 buses with more advanced technology were also available. It has been found that carbon monoxide (CO) levels from early Cummins L-10 CNG powered buses varied greatly from bus to bus, with the higher values ascribed to either faulty catalytic converters or a rich idle situation, while the later model CNG L-10 engines offered CO levels considerably lower than those typical of diesel engines. The NO{sub x} emissions were on par with those from diesel L-10 buses. Those natural gas buses with engines adjustedmore » correctly for air-fuel ratio, returned very low emissions data. CNG bus hydrocarbon emissions are not readily compared with diesel engine levels since only the non-methane organic gases (NMOG) are of interest. Data show that NMOG levels are low for the CNG buses. Significant reduction was observed in the particulate matter emitted by the CNG powered buses compared to the diesel buses, in most cases the quantity captured was vanishingly small. Major conclusions are that engine maintenance is crucial if emissions are to remain at design levels and that the later generation CNG engines show marked improvement over the earlier models. One may project for the long term that closed loop stoichiometry control is desirable even in lean burn applications.« less

Potassium/manganese nitrogen oxide traps for lean-burn engine operation

Abstract: The invention is a nitrogen oxide trap comprising a porous support; and catalysts consisting of manganese and potassium loaded on the porous support. The trap may be used in an internal combustion engine exhaust gas catalyst system. During lean-burn operation of the engine the trap sorbs nitrogen oxides and releases the nitrogen oxides during decreased oxygen concentration in the exhaust gas.

Formation of Hydrogen Cyanide over Cu/ZSM-5 Catalyst Used for the Removal of Nitrogen Oxides from Exhausts of Lean-Burn Engines.

Abstract: Our experiments demonstrate the formation of harmful byproducts during the selective catalytic reduction of NO{sub x} over Cu/ZSM-5. The presence of water in the exhaust gas does not eliminate the hydrogen cyanide formation problem. This behavior together with the limited thermal stability renders this catalyst doubtful for the application in diesel exhaust systems. On the basis of the results of this and our previous studies, it seems advisable to reexamine the catalytic performance of other zeolite and oxide catalysts that have been proposed to be suitable for the removal of NO{sub x} under lean gas conditions. Avoidance of HCN formation adds another criterion for the suitability of future lean exhaust catalyst developments. Studies concerning the reaction mechanism are presently undertaken in our laboratory aiming at the design of catalysts that do not produce hazardous HCN. 26 refs., 4 figs., 1 tab.

Exhaust emission control method for internal combustion engine, exhaust emission control device suitable for the method, and deterioration degree of catalyst detecting device

Abstract: PURPOSE:To provide an exhaust emission control method to prevent the increase of a total amount of NOx exhausted during deterioration of a lean NOx catalyst and to provide a deterioration degree of catalyst detecting device to perform decision of deterioration with accuracy and high stability CONSTITUTION:Based on the temperature TCAT of a leans NO catalyst, a deterioration factor R is calculated and integrated at intervals of 10 seconds to execute processing for updating the degree K of deterioration at S10-S40. From a non-volatile memory, the degree K of deterioration is read and in a case of K>=-Kbs, an O2 feedback condition is varied at S110-S130 so that an operation region on which feedback control is applied in a stoichiometeric amount of air is widen and a lean burn region is narrowed. As a result, a region where NOx is purified by a three-dimensional catalyst is widened on the whole of running and though a fuel consumption is slightly increased, an amount of NOx discharged in the atmosphere air on the whole of running is prevented from an increase.

Lean combustion characteristics of locally stratified charge mixture: Basic studies of in-vessel combustion ignited by laser

Abstract: In order to study the trade-off between improved lean combustion and reduced NO x emissions under a locally stratified charge mixture, this paper examines the effects of the rich mixture volume on combustion duration and the NO x emissions under the same total equivalence ratio in a combustion vessel. The rich methane-air mixture in a soap bubble was ignited at the center of the bubble by a pulsed YAG laser. As a result, it was found that the magnitude of the NO x emissions does not increase as the rich mixture volume increases up to a critical volume, but the combustion duration at that time shortens remarkably. The same tendency was also obtained by means of computer simulation using a 4-cylinder lean burn engine.

Exhaust emission control device of lean burn type internal combustion engine

Abstract: PROBLEM TO BE SOLVED: To effectively perform NOx purification during lean operation without deteriorating driveability, in regard to an exhaust gas emission control device for a lean-burn type internal combustion engine. SOLUTION: An exhaust system of the lean-burn type internal combustion engine is provided with an NOx purifying member having a characteristic that NOx purifying efficiency is reduced as time lapses when the engine is operated in a lean-burn condition, but that the NOx purifying efficiency is recovered when the operating condition is switched to an operating condition at a stoichiometric air fuel ratio or an air-fuel ratio richer than the stoichiometric air fuel ratio. The exhaust gas emission control device is provided with an air fuel ratio control means for switching the mixed ratio of air to fuel fed into the internal combustion engine; an output reduction means for reducing output by decreasing intake air amount to the internal combustion engine; and a control means 25 for the internal combustion engine for temporarily switching the air fuel ratio from a stoichiometric condition to a rich condition without changing the output of the internal combustion engine, and for gradually performing this switching. COPYRIGHT: (C)2005,JPO&NCIPI

Lean burn controller for internal combustion engine

Abstract: PURPOSE:To provide a lean burn controller, by which operation at a stable combustion limit can be carried out by detecting a combustion condition of an engine, for an internal combustion engine. CONSTITUTION:In an ECU 23, a rotation fluctuation index is computed from a rotation fluctuation instantaneous value in a combustion stroke of each cylinder on the basis of an input signal from a crank angle sensor 18. If such a condition in which the value of the rotation fluctuation index exceeds the threshold value occurs for the predetermined times or more during the predetermined control cycle, it is determined that an air-fuel ratio of the cylinder already enters the lean side beyond the stable combustion limit and abnormal combustion occurs. In this case, in the ECU 23, an increasing quantity correction value for each cylinder corresponding to a fluctuation integrated value for each cylinder is set and a fuel correction factor for each cylinder is computed, and then, a target air-fuel ratio for the cylinder is corrected in the predetermined correction area.

Catalysts for natural gas emission control applications

Abstract: Several parameters that affect catalytic methane oxidation on a natural gas vehicle were investigated with laboratory aged noble metal catalysts and a simulated vehicle exhaust. These include the air/fuel control strategy, the noble metal loading, the role of base metals and the exhaust hydrocarbon composition. The catalytic performance of several formulations was compared both slightly fuel-rich of the stoichiometric point and under extreme lean conditions. Catalyst formulations different from those used near the stoichiometric point appear to be required if the vehicle is run under extreme lean conditions, such as those found with diesel engines. Under diesel conditions low exhaust temperatures may pose a challenge, since methane requires relatively high temperatures for catalytic oxidation. Spark ignition lean burn engines might offer a higher temperature exhaust, but NOx conversion becomes more problematic in this environment. Increasing the Pd load improves methane and NOx conversions near the stoichiometric point and methane activity under lean conditions. Ce addition was found to be beneficial for aged catalyst performance and increasing the Ce loading resulted in improved methane activity over Pd near the stoichiometric point. For natural gas vehicles run under closed loop control near the stoichiometric point, the composition of the controlled exhaust will modulate around the set point. The effect of the amplitude and frequency of these modulations on methane oxidation was explored. Increasing the frequency or decreasing the amplitude of exhaust modulations results in improved methane conversions, especially near the maximum methane conversion point. The effect of natural gas fuel composition was investigated with feedstreams containing various hydrocarbon mixtures. Small amounts of propane in the feedstream led to increased hydrocarbon conversions lean of the stoichiometric point. This improvement may be due to propane reacting with and removing surface oxygen species, which otherwise block methane adsorption on the catalyst surface. Larger amounts led to improvements in hydrocarbon conversion rich of the stoichiometric point as well, due to the easier oxidation of propane. The information gained from the above studies was used to design a catalyst for a natural gas vehicle tested by the U. S. EPA. With this catalyst, the vehicle achieved California Ultra Low Emmission Vehicule standards.

Cylinder injection type spark ignition engine

Abstract: PURPOSE:To prevent the abnormal increase of the temperature of an exhaust system without stopping operation of an engine when a misfire owing to open stick abnormality of a cylinder fuel injection valve. CONSTITUTION:A cylinder injection type spark ignition engine comprises a cylinder fuel injection valve 2 connected to a common delivery pipe 8 and injecting fuel directly to the cylinders of an engine 1; a fuel pressure sensor 33 to detect a fuel pressure in a delivery pipe; a sensor 32 to detect the number of revolutions; and a control circuit (an ECU 30) for controlling an engine. The ECU detects the occurrence of a misfire owing to the fluctuation of the number of revolutions of an engine and from a fuel feed amount to a delivery pipe and a fuel injection amount, it is detected that open stick abnormality of a fuel injection amount occurs. During a misfire owing to an opening stick fuel cut and lean burn during deceleration are prohibited. By decreasing oxygen density in exhaust gas from a normal cylinder, unburnt fuel from a misfire cylinder is prevented from being burnt in the exhaust system.

Controller of lean burn internal combustion engine

Abstract: PURPOSE:To achieve effective NOx purification at the time of lean driving for the controller of a lean burn internal combustion engine for carrying out lean burn driving at a condition leaner than the stoichiometry under a specific driving condition. CONSTITUTION:Although the NOx purification efficiency of a NOx purifying member provided on the exhaust system of a lean burn internal combustion engine, when the engine is driven in a lean burn condition, is reduced as time elapses, the NOx purifying efficiency is recovered when the drive condition is switched into a stoichiometry or rich drive condition. The output information from a variable load parameter detection means 59 and an acceleration judged value are compared with one another during lean burn driving, and when the output information is larger than the acceleration judged value, the condition is judged as acceleration driving by an air fuel ratio control means 61, by which the mixed ratio of fuel and air to be fed to the internal combustion engine is switched into a theoretical air fuel ratio condition or a richer side air fuel ratio condition, and when the NOx purifying efficiency of the NOx purifying member is reduced, the acceleration judged value is shifted to a smaller value according to the reduction.

Exhaust emission control device of lean burn internal combustion engine

Abstract: PURPOSE:To purify NOx without degrading drivability at the time of lean driving by providing a purifying member having a recovery characteristic under a specific condition in an exhaust system, and by controlling switching of air fuel ratio without changing engine output. CONSTITUTION:Although the NOx purification efficiency of a NOx purifying member 100 provided on an exhaust channel 4, when driven in a lean condition, is reduced as time elapses, the purification efficiency is recovered when a driving condition is switched into a richer side air fuel ratio. Driving condition of an engine 1 is switched into stoichiometry or rich condition for a specific period of time as each set time period elapses. At the time, the switch valve 86 of an EGR channel 80 is closed during lean driving, and exhaust gas is accumulated in an exhaust gas accumulator 84. At the time of rich control, the switch valve 86 is closed at a set rate to emit accumulated exhaust. The NOx purification efficiency of the exhaust purifying member 100 can thus be recovered rapidly while restricting torque fluctuation.

Detection of hydrocarbons in air and purification of exhaust gas under lean-burn conditions using solid electrolytes

Abstract: A chemical sensor and an electrochemical reactor without the need for the geometry of two electrode compartments have been fabricated using high temperature-type proton and oxide ion conductors, respectively. Pd|CaZr0.9In0.1O3-α Au, responds quickly to dilute hydrocarbons (CH4, C2H6 and C3Hg) in air at 700 °C and changes an electromotive force (EMF) in proportion to the hydrocarbon content. Pd | yttria-stabilized zirconia (YSZ) | Pd, can remove both NO and CH4 in the presence of excess O2 at 700 °C. By passing the direct current through the cell, NO is reduced to N2 at the cathode, and CH4 is oxidized to COx at the anode. The efficiency of removal is independent of the presence of H2O and CO2.