Showing papers on "Spark-ignition engine published in 1987"

Estimating Heat-Release and Mass-of-Mixture Burned from Spark-Ignition Engine Pressure Data

Abstract: A First Law analysis based on the cylinder pressure variation during combustion is a commonly used diagnostic for determining actual spark-ignition engine burning rates. Both simple one-zone and more complex two-zone models have been developed for this purpose. It is shown that the fraction of the fuel's chemical energy which has been released and the fraction of fuel-air mixture burned, within the engine's cylinder, can be accurately estimated from a one-zone analysis if appropriate values for the “average ratio of specific heats”, y¯, of the one-zone contents are used. These values are determined by matching the output of the one-zone analysis to that of the more rigorous two-zone analysis of the same cylinder pressure data. Use of this one-zone burning rate analysis procedure is illustrated.

Fluid Motion Within the Cylinder of Internal Combustion Engines—The 1986 Freeman Scholar Lecture

Abstract: The flow field within the cylinder of internal combustion engines is the most important factor controlling the combustion process. Thus it has a major impact on engine operation. This paper reviews those aspects of gas motion into, within, and out of the engine cylinder that govern the combustion characteristics and breathing capabilities of spark-ignition engines and compression-ignition or diesel engines. Necessary background information and reciprocating engine operating cycles, the primary effect of piston motion and the spark-ignition and diesel engine combustion processes is first summarized. Then the characteristics of flow through inlet and exhaust valves in four-stroke cycle engines, and through ports in the cylinder liner in two-stroke cycle engines are reviewed. The essential features of common in-cylinder flows - the large scale rotating flows set up by the conical intake jet, the creation and development of swirl about the cylinder axis, the flows produced during compression due to combustion chamber shape called squish, flow during the combustion process, and two-stroke scavenging flows - are then described. The turbulence characteristics of these flows are then defined and discussed. Finally, flow phenomena which occur near the walls, which are important to heat transfer and hydrocarbon emissions phenomena, are reviewed.

Cyclically resolved HC emissions from a spark ignition engine

Abstract: A high frequency response (300Hz) flame ionization detector has been used to measure the instantaneous level of HC emissions in the exhaust of an SI engine. The characteristics of the HC signal are observed to be stable and repeatable at mixture strengths around stoichiometry, but at lean mixtures more erratic and complex signals are observed. With the addition of information on cyclic work and ionization levels in the exhaust, a detailed insight into lean combustion problems can be obtained.

Discrete Simplified External Linearization and Analytical Comparison of IC Engine Families

Abstract: A general, nonlinear spark ignition engine model is presented. Speed dependent discretization is employed to develop a linearized formulation for four and six cylinder port fuel injected engine representations. The methods presented provide a foundation for the application of classical or modern control techniques to internal combustion (IC) engine related control problems.

Modeling and Analysis of an Inherently Multi-Rate Sampling Fuel Injected Engine Idle Speed Control Loop

Abstract: This paper develops a model for the idle speed control of a six cylinder. electronically fuel injected, spark ignition engine. The inherently discrete microprocessor based fuel controller is not constrained to operate at the engine's natural sampling rate, resulting in a hybrid (continuous-discrete) multi-rate system. A method for evaluating the stability of the system is developed.

The Autoignition of Isobutane in a Knocking Spark Ignition Engine

Abstract: The chemical aspects of the autoignition of isobutane are studied experimentally in a spark ignition engine and theoretically using computer simulations with a detailed chemical kinetic mechanism. The results of these studies show that with the relatively knock-resistant fuel, isobutane, there is a significant amount of fuel breakdown in the end gas with a resulting heat release and temperature increase. The ability of the kinetic model to predict this low temperature chemical activity is assessed and the model is modified to more closely simulate the experimental observations. It is clear that a reasonable degree of low-temperature chemical activity precedes the autoignition event. We address the basic question or whether this first stage of combustion accounts for a chemical preconditioning of the end gas which leads to th autoignition; of whether it merely provides sufficient heat release in the end gas that the high temperature autoignition is initiated.

Effect of Torch Jet Direction on Combustion and Performance of a Prechamber Spark-Ignition Engine

Abstract: To examine the effect of torch jet direction on the combustion characteristics and engine performances, a spark-ignition engine with each divided chamber having a torch nozzle of different flow direction is used by changing the torch nozzle area, prechamber volume and air-fuel ratio, while keeping the engine speed of 1000 rpm. Typical pressure diagrams for different torch jet directions are analyzed to obtain such combustion characteristics as the crank angles of combustion start and finish, heat release rate and mass burned fraction. The engine performances, e.g. mean effective pressure and specific fuel consumption, are also measured. As a result, it can be made clear not only the effect of torch jet direction on the combustion characteristics, but also the relationship between the combustion characteristics and the engine performances for different torch jet directions.

Spark Ignition Engine Cold Starting with Methanol-Based Fuel Blends

Abstract: Methanol fuelled spark ignition engines have poor low-temperature starting capabilities. Since the problem is one of fundamental volatility, blending volatile additives with methanol can improve cold starting. In this study, minimum starting temperatures were determined for neat methanol, a 90% methanol fuel blend and seven 85% methanol fuel blends. The carburetted engine was from a 1.6 litre Escort produced for operation on methanol-based fuels. Starting was possible below -35 degrees C with some of the M85 fuels. Instances of stalling during the engine acceleration from cranking to idle speed were found to be due to lean excursions in the fuel/air ratios delivered to the cylinders. M85 fuels primed with n-butane required the least cranking time before starting. (A) For the covering abstract of the conference see IRRD 853507.

Operation of a Caterpillar 3516 spark-ignited engine on low-Btu fuel

Abstract: The use of an engine-generator package, fueled by landfill gas, to produce usable electrical power has generated considerable interest among both landfill operators and engine manufacturers. Landfill gas operation presents some unusual technical challenges that require preparation of the gas prior to engine consumption as well as modifications to the spark-ignited engine. The primary obstacles to landfill gas operation are the low-Btu content of the gas, its poor combustion characteristics, and fluctuations in the heating value of the gas. Even so, the engine was not derated from the standard natural gas generator set rating of 762 kW net electrical output. In addition, the engine performance was optimized to meet the EPA site laws for stationary gas engines while still maintaining very low brake specific fuel consumption (BSFC). Finally, 90 days of continuous operation demonstrated engine durability.

Spark-ignition engine

Abstract: There is disclosed a spark-ignition engine having a combustion chamber in which cavities are formed. The cavities are in communication with each other via a communication passage. Air-fuel mixture is appropriately held in the cavities. Spark plugs are disposed near the centers of the cavities to ignite the mixture at plural positions. At the top dead center, the clearance between the top surface of the piston and the lower surface of the cylinder head is made small to minimize useless space. A large squish area is provided to effectively collect the mixture in the cavities. Since the combustible mixture is always held in the vicinities of the spark plugs, stable and rapid combustion can be realized.

Improvements in early flame development in a spark ignition engine brought about by Spark-Aider fuel additives

Abstract: The effects of certain fuel additives—alkali and alkaline earth metal compounds collectively known as “spark-aiders”—on early flame development in a spark ignition engine have been investigated using a laser based technique for flame speed measurement. Iso-octane and unleaded gasoline were the fuels used and two different engines were considered. The results for a calcium and two potassium additives are presented and demonstrate that “spark-aiders” increase early flame development rates and reduce cyclic variation. The leaner the mixture, the more marked is this improvement. As the additive concentration is increased, the maximum improvement in combustion characteristics brought about by the additive increases up to a limiting value and the rate at which this improvement occurs also increases. There is a minimum additive concentration below which no effect can be observed. The “spark-aider” effect, once fully established, lingers on, though at a progressively decreasing level, when the engine is switched ...

Feasibility evaluation of reformed methanol usage to spark ignition engine

Abstract: To improve the cold starting and low load driveability problem in a methanol fueled car, a reformed methanol fueled si engine with a small methanol reformer using exhaust thermal energy as a heat source was developed and tested. Half of the methanol supplied to the engine was reformed to hydrogen and carbon monoxide, and the rest was supplied in a liquid state. As a result, this engine produces less power than the neat methanol fueled engine. But brake specific fuel consumption of this engine is lower based on the calorific value than that of the neat methanol fueled engine in the wide range of excess air ratio. The co emission levels are not significantly different, whereas the hc emission levels are lower than those from the neat methanol fueled engine. The nox emission levels are higher than those from the neat methanol fueled engine but this problem can be solved by lean burn (a).

Method of running a four-stroke spark-ignition engine

Abstract: Method of running a four-stroke spark-ignition engine with not specially hardened seats for the exhaust valves, using an unleaded carburettor fuel which contains 1 to 100 ppm, preferably 5 to 20 ppm, of ferrocene (bis- pi -cyclopentadienyl iron). Due to the addition of the ferrocene readily soluble in fuel, the exhaust valves are protected from excessive wear even at increased speeds and under more severe running conditions.

Engine control and combustion quality detection system and method

Abstract: A system is provided for controlling an internal combustion engine (10) and detecting combustion quality such as knock. A knock sensor (22) senses knock in the engine. A memory (25) and a calculation device (26) establish a base value for an engine control input, such as spark advance in a spark ignition engine. A generator (30) periodically perturbs the control input about the base value. A calculation device (31) determines a combustion quality value by calculating the slip of the output of the sensor (22) with respect to the control input. Means (36-39) may be provided for updating a correction schedule for the control input. Such a system may also be used for engine roughness with the engine control input being air/fuel ratio.

The performance characteristics of indolene-mpha blends in a spark ignition engine

Abstract: A study of the performance characteristics of Indolene- Methanol Plus High Alcohols (MPHA) has been completed. The study includes the measurement of fuel properties and performance parameters. The fuel properties investigated are distillation characteristics, heat of combustion, flash point, specific gravity and water tolerance. The performance parameters measured are MBT spark advance, power output and thermal efficiency. The alcohol concentration was varied from 0 to 100 percent by volume in clear indolene. The measurement of fuel properties indicated that, in general, MPHA-indolene blends have higher water tolerance, similar specific gravity, similar flash point and different distillation characteristics compared to methanol- indolene blends. The performance parameters were measured using a single cylinder CFR spark ignition engine at different compression ratios. The results of the performance measurements indicated that indolene-MPHA blends have a higher MBT (minimum advance for best torque) spark advance, similar power output and lower thermal efficiencies than indolene-methanol blends. (A) For the covering abstract of the conference see IRRD 853507.

The effects of spark-ignition engine design parameters on performance and economy : a modelling study

Abstract: Thesis. (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1987.

Validation of turbulent entrainment model in a spark-ignition engine

Abstract: A turbulent entrainment burning model is considered to be a reasonable one for the combustion in a spark-ignition engine. The concept is based on the Blizard and Tabaczynski model. It is important to estimate the turbulence characteristics, turbulent burning velocity, flame surface area and several experimental constants. Nevertheless, the examination of these values are insufficient, regardless of using many assumptions in previous studies. In this study, turbulence characteristics, the initial stage of burn duration and turbulent burning velocity were discussed in detail. This model was examined under various conditions of engine speed (600-1200 rpm), compression ratio (3.2-4.8) and ignition timing. The calculation results of mass fraction burned, burn rate and burn duration were in good agreement with the experimental ones. It was found that this model was valid for predicting the combustion in a spark-ignition engine.

Spark Ignition Process in Internal Combustion Engines

Abstract: In recent years, due to the restrictions on exhaust emission and fuel consumption in spark ignition (SI) engines, better ignition systems are needed. In recent fundamental studies of spark ignition, important factors affecting the ignition ability or minimum ignition energy have been investigated [1–5]. These help to obtain optimum conditions in practical ignition systems. However, the mixture conditions in practical SI engines is complicated by high turbulence and variation in fuel concentration [6–9]. Also, flame kernel structure and its formation process have been the subjects of chemical and pysical modeling [10–13]. In practical applications, some new ignition methods have been proposed to assure ignition of mixtures difficult to burn, such as plasma jet ignition, two successive sparks, breakdown spark, laser ignition etc. [14–19]. In the present paper, several topics are discussed, most of them emanating from the authors’ laboratory. The discussions are concerned particularly with very short and rather long duration sparks; the former corresponds to capacitance and the latter inductance components of the composite spark, which is used in most current SI engines.

Device for controlling ignition timing for spark ignition engine

Abstract: PURPOSE:To prevent knocking with good response while improving fuel consumption and output by detecting combustion light to monitor the condition of combustion, and controlling ignition timing to be a condition that self-ignition takes place without being brought to knocking. CONSTITUTION:A combustion light signal is inputted into an optical filter 5 by means of an optical fiber 4 installed in a combustion chamber 3, and components peculiar to self-ignition and knocking combustion are selected, which are transduced into electric signals by a photo-detector 6. Among these signals, only components peculiar to knocking and self-ignition are sent to a knocking judging circuit 12 and a self-ignition judging circuit 13 through filters 10 and 11 respectively, from which components which are greater their respective reference voltages, are inputted into a control circuit 14 as a knocking or a self-ignition signal. The control circuit 14 carries out the lead angle of ignition timing until a self-ignition existing condition is detected. On the other hand, this lead angle control is stopped if a signal of knocking is inputted, immediately carrying out a lag angle by a certain quantity on the contrary.

A theoretical analysis of basic cycle for hydrogen addition to the methanol fueled spark ignition engine.

Abstract: In this paper the theoretical cycle of OHV type single cylinder engine which carburetes hydrogen and methanol is compared with its actual cycle.That the change in number of molecules in combustion is independent of the excess air ratio and the residual gas fraction. When hydrogen methanol feed ratio is equal to or less than 0.0625, the number of molecules in combustion is increased and it usually has beneficial effect on engine performance, which is not the case when hydrogen only is supplied.Final temperature (or pressure) of compression and theoretical thermal efficiency increase progressively as hydrogen methanol ratio and excess air ratio increase.The heating value and final temperature of combustion decrease gradually in proportion to the increase in excess air ratio and to the decrease in hydrogen methanol ratio.However, when hydrogen methanol ratio is decreased rise of the final pressure of combustion is seen caused by the mole variation with combustion.The temperature rise ratio for combustion is nearly independent of hydrogen methanol ratio, whereas at a relatively high excess air ratio, only small curve differences between hydrogen methanol ratio are found. In contrast, the effect of hydrogen methanol ratio on degree of explosion is larger at lower excess air ratio.It is observed that the variation in actual engine brake horsepower by the increase in amount of hydrogen supplemented to methanol is almost the same, when it is compared with the results of the calculation method which was treated in this work.

Air-fuel ratio control device for spark-ignition engine

Abstract: PURPOSE: To improve exhaust emission purifying performance by providing an auxiliary valve device controlled according to the heating value of fuel in a branch fuel path bypassing a flow control valve in an engine where there is provided a fuel by-path by-passing a mixer for mixing air and fuel, and the flow control valve is disposed in the midway of the fuel by-path. CONSTITUTION: A gas engine is constructed so that a discharge port of a mixer 4 is connected to the starting end of an intake pipe 2, the terminal end of an air supply path is connected to one inlet of the mixer 4, and the terminal end of a fuel supply path 6 extended from a fuel gas supply source is connected to the other inlet. A by-path 8 bypassing the mixer 4 for supplying fuel gas to the intake pipe 2 is connected to the fuel supply path 6 downstream from a gas regulator 7, and a flow control valve 9 is interposed in the midway of the by-path. In this case, a branch fuel path 10 by-passing the flow control valve 9 to be connected to the by-path 8 is connected to the fuel supply path 6 further downstream from a portion where the by-path 8 branches off, and an auxiliary valve device 11 is interposed in the midway of the path 10. The device 11 is controlled according to the heating value of fuel gas. COPYRIGHT: (C)1989,JPO&Japio

Numerical Simulation of Laminar Flame Propagation in Constant Volume Vessels

Abstract: Recently, computer technology has advanced to a point, where it is possible to numerically simulated combustion phenomena in the spark ignition engine [1,2], though some numerical difficulties still exist [3]. Such simulation provides a deep understanding of the phenomena and thus offers useful suggestions for engine designers creating new engines of high efficiency and low pollutant emission [4].

Application of conditional sampling to the study of cyclic variability in a spark ignition engine

Abstract: Conditional sampling of cylinder pressure data is used to investigate cyclic variability in a premixed charge, spark ignited engine operating under fuel lean conditions. Unlike straight ensemble averaging of pressure data, conditional sampling applies a set of constraints to the pressure data such that like combustion events can be identified and grouped together. Ensemble averaging of pressure data from an engine that exhibits significant cycle to cycle variation is shown to produce a mean pressure history that is not representative of the combustion process. Conditional sampling provides a means of identifying and analyzing the different groups of pressure histories and therefore the different types of combustion processes that occur in an engine that exhibits cyclic variability (a).

Gas Velocity and Turbulence Measurement in a Spark Ignition Engine Using a LDA with a Fiber-Optic Pick-Up

Abstract: The laser Doppler anemometer (LDA) was the first instrument used to measure the unsteady flow velocity and turbulence in the combustion chamber of a reciprocating engine under firing conditions. It has been used in quantitative measurements of gas flow velocity, which varies according to combustion chamber geometry and engine operating conditions. This has fostered the development of engines with low fuel consumption and less pollution.