Showing papers on "Spark-ignition engine published in 1983"

The Effect of Chamber Geometry on Spark-Ignition Engine Combustion

Abstract: The way in which combustion chamber geometry affects combustion in SI engines was studied using a quasi-dimensional cycle simulation. Calculations were performed to investigate the following questions: (i) the sensitivity of geometric effects on combustion to engine operating conditions; (ii) the differences in burn duration between ten chamber geometries and spark plug locations; and (iii) the relative merits of improved chamber design and amplified turbulence as means to reduce burn duration. The results from these studies are presented and discussed.

Alternative fuels for spark ignition engines

Abstract: Toward the end of this century the shortfall of supply below demand of the products of natural crude oil will become severe. Research is already well under way to provide alternative fuels for spark ignition engines which will be independent of natural crude oil. These include fuels from oil shales and tar sands, as well as synthetic fuels, alcohols, and gases; sources include coal, natural gas and biological origins. These fuels will cost two to three times as much in real terms as gasoline from oil does now, so an even stronger emphasis on fuel economy will be required. Most of these alternative fuels are more suited to the spark ignition engine than the compression-ignition engine, and this paper predicts that the changeover to them will cause an increase rather than a decrease in the market penetration of the spark ignition engine. It is concluded that the alternative fuel most likely to gain general acceptance is synthetic gasoline made from coal or natural gas, or in some areas from agricultural by-products.

Measurements and predictions of the precombustion fluid motion and combustion rates in a spark ignition engine

Abstract: Laser Doppler velocimeter results are presented for the mean velocity and turbulence intensity measured in a motored research engine. The compression of complex bulk motions created during induction produces turbulence as the piston approaches top dead center. The turbulence field is shown to be isotropic but nonhomogeneous. A zero-dimensional computer simulation based on an averaged k-epsilon model is shown to adequately predict the decay of turbulence at a point in the flow after the production phase is completed. Cylinder pressure measurements were recorded for homogeneous stoichiometric combustion for a range of engine speeds and ignition locations. A two-zone (burned and unburned gases) thermodynamic model accurately predicts the measured pressure histories when the turbulence results determined from the motored tests are used to establish initial conditions for the combustion model.

Analysis of Hydrocarbon Emissions Mechanisms in a Direct Injection Spark-Ignition Engine

Abstract: The direct injection spark-ignition engine is the only internal combustion engine with the potential to equal the efficiency of the diesel and to tolerate a wide range of fuel types and fuel qualities without deterioration of performance. However, this engine has low combustion efficiency and excessive hydrocarbon emissions when operating at light load. In this paper, potential sources of hydrocarbon emissions during light load operation are postulated and analyzed. The placement of fuel away from the primary combustion process in conjunction with a lack of secondary burnup are isolated as important hydrocarbon emissions mechanisms. Analyses show that increasing cylinder gas temperatures can improve secondary burnup of fuel which would reduce hydrocarbon emissions. Practical means to achieve this include higher compression ratio and use of ceramic parts in the combustion chamber.

Combustion Chamber Effects on Burn Rates in a High Swirl Spark Ignition Engine

Abstract: Experimental measurements of burn rates have been carried out in a single cylinger homogeneous charge engine. Three different combustion chambers were investigated (75 % and 60 % squish bowl-in-piston chambers and a disk chamber) using a cylinder head with a swirl producing intake port and near central spark location. Data were obtained with each combustion chamber as a function of spark timing, EGR, and load at 1500 RPM. The combustion rate is strongly influenced by chamber shape. The 10-90 % burn durations of the 75 % and 60 % squish chambers are respectively about 40 % and 60 % that of the disk chamber. Chamber configuration had less effect on 0-10 % burn duration. The disk had about 25 % longer 0-10 % burn time than the bowl-in-piston chambers. Modifications to the GESIM model enabled good overall agreement between predictions and experimental data, a rather severe test of the model because the coupling of fluid mechanics, combustion and chamber geometry must be properly modeled. An improved basic understanding of the influence of combustion chamber shape on burn rate has been achieved through the interactive use of experimental data and modeling. The results suggest that differences in turbulence intensity and flame area development due to changes in chamber shape are responsible for the observed burn rate differences.

Turbocharging for fuel efficiency

Abstract: The arguments are given for the application of a 1.3 litre turbocharged spark ignition engine, as a substitute for a 2 litre normally aspirated engine as the power plant for a compact-sized car in the late 80's. Three stages of the project leading to an optimised engine-turbocharger package are outlined. Achievement of Stage 1, leading to evaluation of a non-optimised configuration, will be reported. Description includes the use of a separately driven supercharger to define operating limits in the experimental variable matrix comprising compression ratio, boost pressure, EGR rate and spark retard at the knock limit. Computer programs for the optimising stages of the project are outlined. The current status of the project is reported, where, even at this early stage, fuel consumption reductions of 11-22% have been achieved under simulated urban driving conditions.

A Thermodynamic Simulation Model for a Methanol Fueled Spark Ignition Engine

Abstract: A thermodynamic simulation model for the 4-stroke cycle of a single cylinder spark ignition engine operating on neat methanol is described in this paper The development of the model for all the processes is illustrated It computes the gas pressure, gas temperature and the rate of formation of nitric oxide and carbon monoxide at each crank angle using basic energy equation and reaction kinetic mechanism A gas exchange model has been formulated by finite difference scheme to evaluate the mass flow rate through valves and the properties in the intake and exhaust systems The validation of the above model has been carried out by comparing the predicted and experimental data at different operating conditions encompassing changes in fuel-air equivalence ratio, speed, load, spark timing and compression ratio The special characteristics of methanol such as rapid burning rate, high power output and reduced nitric oxide emissions have been truthfully predicted by the model

Catalytic late direct injection spark ignition engine

Abstract: A late injection direct injection stratified charge spark ignition engine is provided with a catalytic grid disposed in the path of injected fuel spray and downstream of the point of spark ignition to assist the completion of combustion of previously ignited fuel spray as well as to ignite and cause the combustion of previously unignited fuel elements passing therethrough. Improved combustion and reduced hydrocarbons emissions are anticipated.

A Stochastic Model of Turbulent Mixing for the Prediction of Burn Rate in a Spark-Ignition Engine

Abstract: A model for predicting the burn rate of a premixed and stratified internal combustion engine is developed. The model involves an ignition period dominated by mslecular and turbulent diffusion and a combustion period dominated by turbulent diffusion. A correlation based on a deterministic model for the structure of turbulence is used. This correlation employs turbulent flow characteristics and the laminar flame speed. A statistical model based on turbulence characteristics which employs a Monte Carlo technique to follow the mixing process is developed to describe the combustion period. This model is used to predict the effects of spark advance, exhaust gas recirculation, and stroke variation on the burn rate of a premixed charge engine with no intake swirl. The effect of mixture stratification is also explored. The model agrees well with the experimental data and predicts the correct trend for the effect of spark advance, exhaust gas recirculation, and stroke variation. With increased mixture stra...

A method for automatically regulating the time of combustion initiation in an internal combustion engine

Abstract: A method is provided for automatically controlling the ignition time in a spark ignition engine or the injection time in a compression- ignition engine wherein at least one phenomenon characteristic of the running conditions of the engine, such as the occurrence of the peak pressure in a cylinder in a certain angular interval of the crankshaft, or detection of passage of the flame front through a reference position of a combustion chamber, is detected. A statistical, e.g. mean value representative of at least P measurements of said phenomenon is determined and this value is used to modify the time of combustion initiation so that the statistical value adops a predetermined value corresponding to the desired running conditions. Accelerometers or ionisation probes 64a-d are connected to circuit 66a-d which detect the angular position of the crankshaft at which the phenomenon occurs and supply signals to processing circuits 69a-d which determine the statistical value of the crankshaft position. Circuits 70a-d determine the ignition advance such that the phenomenon occurs at the predetermined value. During starting, an engine speed sensor 76 or an engine load, temperature or throttle position sensor 77 controls the ignition advance. A knock sensor 78 provides a priority signal to control the ignition advance to prevent knocking.

A Single Cylinder Engine Study of Lean Supercharged Operation for Spark Ignition Engines

Abstract: A comprehensive test program was conducted using a single cylinder CFR engine to evaluate lean supercharged operation (LSO) of the spark ignition engine for improved efficiency The intake manifold pressure and temperature and the exhaust pressure were controlled to simulate the addition of a turbocharger to the engine Results of the experimental work indicated that LSO has the potential of improved engine efficiency and NOx emissions comparable to, or lower than, the naturally aspirated engine For equal power output from the engine, efficiency increases of 14% were accompanied by reductions in Brake Specific NOx (BSNOx) emissions of approximately 76% For a case of equal BSNOx emissions, an efficiency improvement of 64 points (over 40%) was observed For operation at realistic lean supercharged conditions, the hydrocarbon and carbon monoxide emissions were not significantly different than those for the naturally aspirated engine Exhaust energy estimates for the lean supercharged conditions tested indicated that sufficient exhaust energy is available to power a typical automotive type turbocharger

The effect of cyclic dispersion of combustion pressure on working parameters of a spark ignition engine

Abstract: The paper deals with the phenomenon of cyclic dispersion of firing pressure in an Otto engine and some factors affecting this process. On the basis of the results of investigations carried out with the use of an experimental engine, criteria for evaluation of the process have been determined and expressed as a function of variable working conditions of the engine. From the example of auxiliary systems employed in the engine experiment some possibilities of practical reduction of cyclic dispersion of firing pressures have been presented. Some attempts have been made to find a correlation between the cyclic dispersion of firing pressure and economy of the engine as well as the content of toxic components in the exhaust gases.

Cold starting tests on a methanol fuelled spark ignition engine

Abstract: The present cold starting performance of methanol fuelled spark ignition engines is poor compared to their gasoline counterparts. Apparatus has been developed to cold soak a small engine to temperatures as low as -65/sup 0/C. Tests have been conducted using methanol, Indolene and sample of commercial gasoline of depressed volatility. Data are provided showing the effect of fuel-air ratio on minimum starting temperature for the three fuels. Methanol failed to start at temperatures below about 0/sup 0/C whereas the Indolene started easily to below -45/sup 0/C. Reid Vapour Pressure is shown to be ineffective as a predictor of cold starting performance for methanol.

Spark-ignition engine with an eccentric piston combustion chamber

Abstract: The eccentrically located combustion chamber 9 in the piston 3 has substantially flat sloping side walls extending between the approximately eliptical opening 12 and the substantially flat approximately eliptical chamber bottom 11. The regions 18 and 18a of the piston head about the opening 12 approach the facing flat cylinder head surface to provide squish. A spark plug 20 and valve controlled inlet and exhaust ports 5 and 6 are located in the cylinder head (1), Fig. 1 (not shown), over the opening 12.

Comparative performance study of spark ignition engines burning alcohols, gasoline, and alcohol-gasoline blends

Abstract: In recent years it has been clear that the reserves of oil, from which petrol is refined, are becoming limited. In order to conserve these stocks of oil, and to minimize motoring costs as the price of dwindling oil resources escalates, it's obviously desirable to improve the thermal efficiency of the spark ignition engine. There are also obvious benefits to be obtained from making spark ignition engines run efficiently on alternative fuel, (non-crude based fuel). It has been claimed that hydrogen is an ideal fuel for the internal combustion engine it certainly causes little pollution, but is difficult to store, high in price, and difficult to burn efficiently in the engine without it knocking and backfiring. These problems arise because of the very wide flammability limits and the very high flame velocity of hydrogen. Alcohols used an additive or substitute for gasoline could immediately help to solve both energy and pollution problems. An experimental tests were carried out at Mansoura University Laboratories using a small single cylinder SIE, fully instrumented to measure the engine performance. The engine was fueled with pure methonol, pure ethonol, gasoline methanol blends and gasaline ethanol blends. The results showed that in principle, from kechnological aspectsmore » it's possible to use alcohols as a gasoline extender or as alcohol's gasoline, blends for automobiles. With regard to energy consumptions alcohols and alcohols gasoline blends lead to interesting results. The fuel economy benefits of using alcohols gasoline blends was found to be interesting in the part throltle operation.« less

Modeling for mass burning rate and combustion duration in spark ignition engines using gasohol fuels

Abstract: This paper presents an analytical model for the prediction of mass burning rates and combustion duration via analysis of pressure versus time data, physical engine design parameters, and the thermodynamic properties of the fuel. For model verification pressure and ion discharge traces were obtained for five methanol-gasoline blends burned in a single cylinder spark ignition engine. A new computational technique, built upon earlier Russian works, is presented to provide a more accurate model for the density of the combustion gases during combustion. The accuracy of the model predictions is substantiated through comparison with heat release data and flame front position data as recorded by ion discharge transducers.

Control method of exhaust gas returning in spark- ignition engine

Abstract: PURPOSE:To prevent an engine from lowering in charging efficiency by increasing EGR ratio in proportion to the increase of the number of revolutions of the engine and reducing the EGR ratio in the area of high-load operation. CONSTITUTION:An exhaust manifold 6 is connected to a surge tank 4 via an exhaust gas returning pipe 8, an exhaust gas returning control valve 9, and an exhaust gas returning pipe 10, and a part of exhaust gas is conducted into the surge tank 4. The exhaust gas returning control valve 9 increases EGR ratio in proportion to the increase of the number of revolutions of an engine; it keeps the maximum EGR ratio at a constant value in the area of medium load operation and reduces the above-said constrant value in proportion to the increase of the load of the engine in the area of high-load operation.

Butanol—Acetone Blends as S.I. Engine Fuels

Abstract: POWER and thermal efficiency of a spark ignition engine fueled by butanol-acetone blends were roughly equivalent to gasoline. Mixture distribution was less uniform with the blends, reducing the speed and load flexibility of the engine. Mixture temperature, exhaust temperature, and oxides of nitrogen emissions were all reduced while operating on the blends.

Turbocharging for the fuel efficient urban car

Abstract: The arguments are given for the use of a 1.3 Litre turbo charged spark ignition engine as a substitute for a 2 litre normally aspirated engine for late 80's compact cars. Descriptions of the three stages leading to an optimised engine turbocharger package are described, together with details of the prototype tc engine manufacture and testing including supercharger tests to define operating limits. An outline of the optimising computer program is given, together with examples of computed camshaft designs giving significantly improved performance at low engine speeds. Some experimental results are given, including those of in car testing which showed fuel consumption reductions of 12- 22 per cent over urban driving cycles (a).

Detecting combustible or combustion-supporting constituents in exhaust gas from an internal combustion engine

Abstract: A method and apparatus are provided for measuring air/fuel ratio for a fuel mixture (particularly for a spark ignition engine). A flow path is provided, for fuel mixture, which contains zones whereby either fuel can be added to lean mixtures or air can be added to rich ones (such additions being termed doping). In a subsequent reaction zone the temperature of, or current through, a conductor is maintained constant. The regulator needed to maintain the constant state enables the point of maximum heat release on combustion of a doped or undoped mixture near the conductor to be determined. A unique relationship between the ratio and such heat release enable the ratio to be determined.

Improved Spark Ignition Engine Efficiency through Lean Turbocharged Operation

Abstract: A production turbocharged V-6 engine of 3.8 liter (231 cu. in.) displacement volume was used in this study of lean turbocharged operation. The engine was modified for lean operation (A/F = 19-20:1) and manual control of the fuel flow, compressor discharge pressure, and EGR rates. Test conditions included loads and speeds to simulate road-load and 4% grade operating conditions, as well as constant intake manifold pressure tests. The results from the test program indicated that lean turbocharged operation has a potential for increased efficiency and reduced NOx emissions if operated at brake mean effective pressures of 500 kPa and above. For these operating conditions, HC and CO emissions are comparable to those of the naturally aspirated engine. NOx emissions were reduced by up to 50% over those for the naturally aspirated engine with EGR. Efficiency increases of up to 3 points (10%) were observed. Satisfactory detonation control for engines operating at these conditions will require comprehensive control of equivalence ratio, spark timing, and compressor discharge pressure.

Spark ignition engine

Abstract: PURPOSE:To accelerate the combustion speed for reducing a thermal loss by shaping a combustion chamber at the piston head in the specific recessed form and disposing an ignition plug on the cylinder side so that the position of plug faces the outer rim of the recess. CONSTITUTION:A combustion chamber at the head of a piston 5, namely a cavity 6 is shaped in such a form that its depth is gradually reduced in the radial direction from the center of the piston 5 to the outside, thereby producing shearing turbulene in the swirl generated during the combustion stroke. An ignition plug 7 is disposed on the cylinder side to be opposed to the peripheral rim of the cavity 6 so as to prevent the thermal pinch.

Comparative assessment of energy consumption and emission characteristics of a spark ignition engine operating on gasoline and methanol

Abstract: The investigations relating to the energy economy and emission characteristics of a spark ignition engine operating on gasoline and neat methanol under carburetion and manifold injection modes are described. The significant aspects of using neat methanol with reference to savings in energy consumption and reduction in exhaust emissions are highlighted.

Computation of NO Levels for Various Operations in SI Engines

Abstract: The method of computation is proposed to estimate NO emission levels of spark ignition engines operating with not only homogeneous but also nonhomogeneous mixtures, because mixture states other than a homogeneous one may deliberately be used to improve pollutant emissions and engine performance. First proposed is a model valid for homogeneous mixtures, and then it is so modified as to be applicable to various nonhomogeneous mixtures such as a stratified charge. These models allow us to survey the relation between NO emissions and the variations of mixture states or operating conditions in SI engines.

Spark-ignition engine with a rotary slide valve for intake and exhaust timing

Abstract: To allow favourable positioning of the ignition electrodes (11, 12) of the ignition device of an internal combustion engine equipped with a rotary slide valve (4) for intake and exhaust timing, at least the ignition electrodes (11, 12) are integrated into the slide valve (4) and in such a way that a chamber (10) in the slide valve (4), which chamber accommodates the said electrodes, is in a central position of communication with the associated combustion space (7) at the moment of ignition (Fig. 1).