Showing papers on "Spark-ignition engine published in 1978"

The Prediction of Ignition Delay and Combustion Intervals for a Homogeneous Charge, Spark Ignition Engine

Abstract: Correlations for the ignition delay and combustion energy release intervals in a homogeneous charge, spark-ignited engine are developed. After incorporation within a simplified engine cycle simulation, predicted values of these two combustion parameters are compared to experimental engine data. The correlations are based on four fundamental quantities--the turbulent integral scale, the turbulent micro-scale, the turbulent intensity, and the laminar flame speed. The major assumptions include: (1) the turbulent integral scale is proportional to the instantaneous chamber height prior to flame initiation; (2) angular momentum is conserved in the individual turbulent eddies ahead of the flame front (i.e., a ''rapid distortion'' turbulence model); and (3) the turbulent intensity scales with the mean piston speed. Two empirical constants scale the correlations to a given engine. Predicted values for the ignition delay and burn intervals show good agreement with experimental results for wide variations in engine operating and design conditions (e.g., engine speed and load, spark timing, EGR, air-fuel ratio, and compression ratio). In addition, the shapes of the predicted mass fraction burned curves agree well with published data.

“Wetting” the Appetite of Spark Ignition Engines for Lean Combustion

Abstract: Single-cylinder spark ignition engine experiments conducted at constant speed, fixed airflow, and using isooctane as the fuel, demonstrated the effects of fuel-air mixture preparation was changed by varying the time of fuel injection in the induction manifold, near the intake valve port. For comparison, a prevaporized fuel-air mixture was also investigated. Emphasis was placed on determining the effects of mixture preparation on combustion characteristics. Based on the results from this study, the often favored prevaporized mixture of fuel and air may not be the best diet for lean engine operation. /SAE/

Effects of combustion-chamber surface temperature on the exhaust emissions of a single-cylinder spark-ignition engine

Abstract: The effect of combustion-chamber surface temperature on exhaust emissions was investigated for wide ranges of air/fuel ratio, speed and volumetric efficiency A single-cylinder research engine was operated on propane over a range of speed (1000 to 2500 r/min), volumetric efficiency (20% to 80%) and air/fuel ratio (13 to 225), while combustion-chamber surface temperature was varied independently It was found that oxides of nitrogen (NOx) emissions significantly increase with increasing surface temperature This effect is strongest at lean air/fuel ratios In rich mixtures, the demonstrated weak influence of surface temperature on NOx emissions is attributed to NO decomposition reactions occurring during the expansion stroke With the exception of the extremely lean condition (225 air/fuel ratio), the sensitivity of hydrocarbon emissions to surface temperature was found to be essentially independent of air/fuel ratio No significant effect of surface temperature on carbon monoxide emissions was found

Wetting the appetite of spark ignition engines for lean combustion. SAE Paper 780234

Abstract: Single-cylinder spark ignition engine experiments conducted at constant speed, fixed airflow, and using isooctane as the fuel, demonstrated the effects of fuel-air mixture preparation on lean operation. Mixture preparation was changed by varying the time of fuel injection in the induction manifold, near the intake valve port. For comparison, a prevaporized fuel-air mixture was also investigated. Emphasis was placed on determining the effects of mixture preparation on combustion characteristics. Based on the results from this study, the often favored prevaporized mixture of fuel and air may not be the best diet for lean engine operation.

Exhaust Emissions and Performance of a Spark Ignition Engine Using Oxygen Enriched Intake Air

Abstract: Oxygen was added to the intake air of a spark ignition engine to determine its effects on exhaust emissions and engine performance. Increasing the content of O2 in the intake air of the engine from 21 to 32 percent by volume, increased exhaust nitric oxide emissions, decreased exhaust hydrocarbon emissions, decreased thermal efficiency and permitted leaner engine operation. These effects can be largely attributed to high flame temperatures and/or flame speeds with Os enriched air.

Alternative Automobile Engines.

Abstract: A technology assessment of various heat engines for automobile propulsion is presented covering: the spark ignition (Otto) engine; the compression ignition (diesel) engine; the vapor cycle (Rankine) engine; the Stirling engine; and the open and closed Brayton cycle (gas turbines) engines. Comparative data given include temperature ratio, thermal efficiency, power to mass ratio, exhaust emissions, and manufacturing cost. The defects of alternative engines to the spark ignition engine are clearer than their virtues, and the choice of a single best alternative is complex. Government policies with respect to the automotive industry are discussed. (PMA)

Some problems and benefits from the hydrogen fueled spark ignition engine

Abstract: Induction ignition or back-flashing associated with H2 engines is shown to be caused by deposit ignition or residual gas ignition. Results from single cylinder engine tests show that operation free of induction ignition is possible at all mixtures and compression ratios up to knock and beyond. Test with a typical automotive engine gave thermal efficiencies on average nearly twice that for gasoline. Specific NOx emissions were always less than with gasoline (1/200 to 1/3), but the maximum torque range could not be explored because pyrolised carbon from the lubricant caused induction ignition which could not be eliminated.

Performance and Emission Predictions of a Multi-Cylinder Spark Ignition Engine with Exhaust Gas Recirculation

Abstract: A multi-cylinder four stroke cycle spark ignition engine equipped with an exhaust gas recirculation (EGR) system to reduce nitric oxide emission has been comprehensively simulated in a computer program including intake and exhaust manifolds The program was tested against experiments performed on a standard production four cylinder four stroke engine equipped with a simple laboratory made EGR system A nitric oxide emission reduction of about 50% was obtained at the peak NO condition In spite of simplified assumptions that comparison between prediction and measurement of some major engine variables was good The simulation program holds promise as a tool for engine development work An appendix is added giving the outline of the calculation procedure

Performance and Emission Predictions for a Multi-Cylinder Spark Ignition Engine with Catalytic Converter

Abstract: A mathematical model is developed to represent an oxidizing catalytic converter in the exhaust system of a spark ignition engine in which the flow is non steady A series of tests were carried out on a four cylinder two litre engine with a carbon monoxide and hydrocarbon oxidizing converter and secondary air injection Comparison of results between experiments and computer calculations shows excellent agreement when the converter is new, but that if the catalyst surface is poisoned or aged the hydrocarbon prediction deteriorates The carbon monoxide predictions, however, remain fairly good Prediction of the overall engine performance and emission levels is very good /SASI/

Clean spark ignition internal combustion engine

Abstract: A two or four-stroke spark ignition engine has fuel injectors located at or near BDC, and a separate recess in its cylinderhead to trap a lean mixture for causing more complete combustion of a rich mixture outside the recess after the rich mixture is ignited.

Method for operating a multi-cylinder jump-spark ignition engine and operation control system thereof

Abstract: In a non-load operation of a multi-cylinder internal combustion engine, both suction flow of newly supplied air-fuel mixture to be introduced in a first combustion chamber and exhaust flow of combustion gas to be exhausted from the first combustion chamber or only the exhaust flow is throttled to carry out compression ignition combustion in the first combustion chamber, while suction flow of newly supplied air-fuel mixture to be introduced into a second combustion chamber is blocked to stop combustion in the second combustion chamber to increase a gas feed rate in the first chamber, to thereby cause a kind of run-on phenomenon in the engine in non-load condition.

Lean mixture running of the spark ignition engine by the generation of a vortex system within the intake

Abstract: The effect of fuel mixture strength and ignition timing on flame propagation in the spark ignition engine was investigated, and the significance of intake-generated turbulence was assessed using a vortex generator (several delta-shaped wings joined at their apexes and positioned in the inlet port). The test vehicle was a single-cylinder, four-stroke, variable compression ratio Renault with a spark ignition engine. The engine was run on gasoline at four speeds (1000, 1500, 2000, and 2500 rpm), and tests were conducted to obtain the optimum spark timing over a range of mixture strengths. Engine speed, throttle angle and ignition timing, and percentage of flame arrivals across the combustion chamber were measured for three conditions: no vortex generator (datum); 50% blockage ratio vortex generator; and 85% blockage ratio vortex generator. Results showed that flame speed and lean extinction limit may be increased by fitting a vortex generator in the engine intake. The vortex generator should be of variable geometry and replace the conventional throttle. The main instrument on the engine consists of a flame logger which accepts amplified signals from ionization probes set in the engine combustion chamber. The logger is gated to count flames which travel across the combustion chamber during a set crank angle period. Information from this instrumentation is presented in the form of graphs describing the effect of vortex generator blockage ratio, mixture strength, engine speed and load, and spark timing on the percentage number of flames which cross the chamber and on the apparent flame speed. It is demonstrated that the beneficial effect of a vortex generator is more pronounced in the lean mixture region and that measured flame speed is increased using the generator.

Fuel feeding method in spark ignition engine

Abstract: PURPOSE:To increase the fuel feeding pressure by arranging a special variable throttle on the passage which interconnects the discharge side with the intake side of the positive displacement pump and to decrease the discharge amount of hydrocarbons by forming the range of turbulent flow from the current by the spray nozzle and retaining the air-fuel ratio at the near theoretical value.

Method of operating 22cycle spark ignition engine and its operational controller

Abstract: PURPOSE:7110 To purify exhaust gas in the case of low loads and to improve fuel cost, by inducing autogenous ignition on a boundary surface with residual gas by means of layer-like admission for supplying fresh air to a lower portion in a cylinder, to stabilize combustion

Research on a Dual-Chamber Stratified Charge Engine

Abstract: One alternative to the problem of improving fuel consumption while reducing high exhaust emissions is the dual chamber stratified charge spark ignition engine. This paper describes the various phases of the research program now being conducted. Its purpose is to better understand the basic combustion process in this type of engine and the fundamental limitations involved. Typical results obtained in the initial phases of study are illustrated.

Diesel engine with cylinder antechambers - has fuel injectors fitting into antechamber inserts positioned in spark plug openings

Abstract: The engine has a cylinder block (1) with a cylinder head (2) above it. The inlet and exhaust valves (6) are in the cylinder head. A fuel injector (12) fits into a holder (16). The holder screws into the end of an insert (17) which has a cylindrical space (18) inside it forming the antechamber. The insert fits into the opening in the cylinder head normally used for a sparking plug in a spark ignition engine. The end of the insert is closed with a small opening (19) into the engine cylinder.

Variable-displacement spark-ignition engine. final report

Abstract: A five-cylinder variable displacement research engine was designed, built, and tested. Displacement is varied by changing the piston stroke using a four-bar linkage. Before the engine was built, its dynamics were thoroughly analyzed, and a five-cylinder configuration was selected to minimize vibration. Test data show that BSFC is, as expected, less dependent on load than in conventional engines, and averages less than 0.5 lb/bhp-hr over the load and speed range of ordinary automobile operation. The impact of exhaust gas recirculation on emissions levels was studied experimentally. Several methods for estimating urban fuel economy from dynamometer data predict a 20 to 25% improvement compared with conventional engines at the same emissions levels. (ERA citation 03:044973)

Photographic characterization of spark-ignition engine fuel injectors

Abstract: Manifold port fuel injectors suitable for use in general aviation spark-ignition engines were evaluated qualitatively on the basis of fuel spray characteristics. Photographs were taken at various fuel flow rates or pressure levels. Mechanically and electronically operated pintle injectors generally produced the most atomization. The plain-orifice injectors used on most fuel-injected general aviation engines did not atomize the fuel when sprayed into quiescent air.

Problems of turbocharging of automotive engines

Abstract: As mentioned in section 2.3, the supercharging of spark ignition aero-engines was already highly advanced at the time when they were superseded by the gas turbine. During and after World War I, the engines were mechanically supercharged, around World War II exhaust turbocharged. There was, however, little incentive to supercharge automobile engines other than those in sports- and racing cars, because it was simpler and cheaper to obtain more power by increasing the size of the engine.

Economic comparison of future automotive power systems

Abstract: This paper presents Exxon Enterprises Inc.'s approach to the economic evaluation of advanced automotive power systems. The paper derives and compares projected initial costs and operating costs for a subcompact car and a full size car powered by four different advanced power systems, i.e. an advanced spark ignition engine, a lightweight diesel engine, a battery powered motor, and a diesel electric hybrid system. /SAE/