Showing papers on "Spark-ignition engine published in 2000"

Direct injection spark ignition engine

Abstract: A method is presented for improving performance of direct injection spark ignition internal combustion engines at high load conditions by increasing the degree of homogeneity of the air-fuel mixture during the intake stroke of the engine. The improved performance is achieved by adding a deflector designed to reduce intake air impinging upon the fuel spray and deflecting it to the intake side of the combustion chamber, thus facilitating better fuel circulation throughout the combustion chamber. This method improves engine performance at high load engine operating conditions.

Low heating value gas on spark ignition engines

Abstract: The performance of a spark ignition engine using low heating value (LHV) gas generated in a fixed bed downdraft (co-current) gasifier, using agricultural and forestry residues was measured on a dynamometer test bench. The parameters measured include torque, power output, emissions measurement, exhaust gas temperature for both operation on gasoline and LHV gas. Improvements in hydrocarbon and carbon monoxide emissions were obtained and the engine suffered less thermal stress under LHV gas operation. The power loss was relatively low, though the experimental arrangement restricted the power output at high throughputs of gas.

Investigation of the mixture formation inside a gasoline direct injection engine by means of linear Raman spectroscopy

Abstract: Linear Raman scattering has been used for the investigation of the mixture formation inside an optically accessible gasoline direct injection spark ignition engine. The concentrations of O 2 , N 2 , H 2 O, and isooctane have been measured simultaneously and cycle resolved along a line of nearly 1 cm at three different locations inside the combustion chamber. By means of polarization-resolved detection optics, it was possible to separate the highly polarized Raman signals from unpolarized contributions from light emissions by stray light from surfaces, background luminescence, or laser-induced fluorescence. A separation between pure air and air/fuel mixture spectra was possible, indicating the influence of air entrainment on mixture formation. As all droplet influences on the taken spectra could be suppressed successfully, only pure gasphase spectra enter the air/fuel ratios evaluated. At the three selected locations (underneath the spark plug and displaced about 1.6 cm toward the intake and toward the outlet valve), the concentrations of all major species have been detected with high spatial and temporal resolution to observe the mixture formation process in a wide area inside the cylinder starting at fuel injection until shortly before ignition. Comparison with two-dimensional laser-induced exciplex fluorescence (LIEF) images allows improved interpretation of the phenomena taking place during mixture formation.

Charge control for direct injection spark ignition engines with EGR

Abstract: Modern automotive engines rely increasingly on high performance estimation and control algorithms to deliver the expected performance benefits. This paper discusses a number of control problems and issues that arise in the design of a charge controller for a lean-burn direct injection spark ignition engine with exhaust gas recirculation (EGR). To deal with uncertainties and parameter variations that can significantly affect the engine performance, the use of feedback and adaptive controllers is shown to be essential.

Technical Note: Combustion characteristics and hydrocarbon emissions of a spark ignition engine fuelled with gasoline-oxygenate blends

Abstract: Combustion characteristics and hydrocarbon emissions in a spark ignition engine operating on oxygenated fuel blends are studied, and the mass fraction burned and engine hydrocarbon emissions are analysed. Calculation results, based on the recorded pressure diagram, show that the flame development and rapid burn angles of gasoline-ether blends generally decrease and the maximum cylinder pressure increases as compared with those of gasoline. The flame development angle and rapid burn angle decrease when the fraction of alcohol fuels in gasoline is small, whereas they increase when the fraction of alcohol fuels is large. The experimental results show that engine exhaust hydrocarbon emissions can be reduced by blending oxygenated fuels in gasoline rather than operating on neat gasoline. Operating on gasoline-ether blends rather than on gasoline-alcohol fuel blends and neat gasoline greatly reduces hydrocarbon emissions. (A)

Free-piston internal combustion engine

Abstract: An internal combustion free-piston pump-engine provides pressurized fluid for a hydrostatic powertrain. The free-piston (4) is reciprocably mounted in a piston bore (3) and transfer combustion pressure directly into pressurized hydraulic fluid. Fast, computer controlled hydraulic two-way valves (17-20) initiate the stepwise pressurization of the smaller face (11), the larger face (12), or both faces of the hydraulic end of the free-piston, controlling the piston movement and especially its top-end and bottom end positions. The control concept can be applied to a two-stroke, or four-stroke compression or spark ignition engine. A pressure wave charger (28), transfers the energy of the exhaust pressure wave into an air intake pressure wave.

Fuel metering effects on hydrocarbon emissions and engine stability during cranking and start-up in a port fuel injected spark ignition engine

Abstract: To gain a better understanding of engine behavior in starting, cranking tests were performed on a 2.OL 4-cylinder Ford Zetec engine. The tests consisted of varying the initial engine position, starting temperature, and fueling strategy during the first two cycles in order to elucidate the effects of these variables on IiMEPg and HC emissions. The engine stopping position is a function of the gas load balance on the piston after the engine has been shut off. The most important effect of that position is on the instantaneous engine speed during cranking, which varies according to the sequence of firing events in the engine during a given cycle. Increased speed increases engine output through improved combustion phasing and heat release schedule. For a given starting position, IIMEPg is fairly insensitive to in-cylinder X within the range of 0.65 to 1.1; this is due to the combination of decreased combustion efficiency and improved heat release phasing. For all temperatures and starting positions, the firing threshold is X 1.1; tests run under colder temperature conditions require more fuel to reach this limit. Hydrocarbon emissions are sensitive to in-cylinder X outside the range of 0.65 to 1.1; lean and rich mixtures result in high HC levels due to misfires and partial burns, respectively. In addition, for a given in-cylinder X, lower temperatures result in higher HC levels. Open valve injection causes non-uniform in-cylinder mixtures, liquid fuel deposits in-cylinder, and spark plug wetting, and is therefore detrimental to engine stability and HC emissions. Thesis Supervisor: Wai K. Cheng Title: Professor of Mechanical Engineering

System and method of controlling air-charge in direct injection lean-burn engines

Abstract: A method and system for controlling the air charge in a direct injection spark ignition engine that provides proportional plus integral control in positioning an electronic throttle control valve and an exhaust gas recirculating valve in order to compensate for uncertainties in the EGR valve flow area. An adaptation algorithm is used to improve the estimate of in-cylinder flow and throttle open-loop control.

A comparison of the relative effects of fuel composition and ignition energy on the early stages of combustion in a natural gas spark ignition engine using simulation

Abstract: Spark ignition engines operating on natural gas (NG) show advantages over petrol and diesel alternatives in terms of precatalyst emissions. However, such engines are affected much more than their petrol counterparts by the long combustion delay of the main fuel component, methane. The sensitivity of combustion delay to fuel/diluent chemistry means that this issue is exaggerated by the presence in the NG of variable concentrations of higher hydrocarbons and of inorganic components, arising from the worldwide variability of NG or from the use of exhaust gas recirculation.The present article reports on a study using a large-scale three-dimensional simulation, incorporating computational fluid dynamics (CFD) and fully detailed chemical kinetics, of the early stages of NG combustion in a spark ignition engine. The focus is on comparing the relative influences of gas composition (i.e. the ethane content of the NG, and carbon dioxide in the oxidant/diluent) with the effects of ignition source location an...

Vibration monitoring as a predictive maintenance tool for reciprocating engines

Abstract: The vibration signature of a four-stroke, four-cylinder carburetted spark ignition engine has been analysed. The significance and contribution of the signature components with respect to the overall information about the engine health have been explored. The engine block vibrations were recorded at four different locations, two in the vicinity of the rear crankshaft bearing and two at opposing sides of the engine block. The vibrations were measured along the three principal axes. It was found that the engine block side is the most sensitive location for collecting data and the direction transverse to the pistons’ movement plane is the most informative one. For the sake of simplicity in possible practical applications in the future the tests were conducted under idle conditions. The measured vibration waveform has been synchronized with the crankshaft position by using the primary coil signal and then transformed to the frequency domain by a fast Fourier transform procedure. Frequencies below 1 Hz ...

EGR control system for internal combustion engine

Abstract: An EGR control system for a direct injection spark ignition engine operated at a plurality of the combustion modes comprising stratified-charge combustion and premix-charge combustion. The system includes a flow rate control valve equipped at the EGR passage to regulate flow rate of the exhaust gas to be recirculated which is operated when the one combustion mode is determined to be changed to another of a plurality of the combustion modes, thereby ensuring an EGR amount that is neither deficient nor excessive for the combustion mode, while preventing misfire from happening and preventing the degradation of drivability, fuel economy and emission performance from occurring. Alternatively, the system includes an actuator for regulating an opening of a throttle valve or a second EGR control valve installed in a branch passage and a passage switching valve for switching the EGR passage and the branch passage.

Direct injection type spark ignition engine

Abstract: PROBLEM TO BE SOLVED: To stratify a mixture and enable stabilized stratified charge combustion by accelerating fuel delivery under an operating condition in which tumble streams damp and collapse. SOLUTION: An exhaust valve 8 is temporarily opened during a compression stroke before fuel injection when an engine is running at low speeds including idling. The valve is temporarily opened by configuring an exhaust valve operating cam 17 with two different types of cams for and selecting either one at an appropriate timing. One of these two cams is provided with a cam nose that opens the exhaust valve 8 during the exhaust stroke, together with a small cam nose that opens the exhaust valve 8 during the compression stroke. An intake valve operating cam 15 is made up of two different types of cams with different operating angles, which advances the timing at which to close the intake valve in an operating condition whereby the exhaust valve 8 is opened during the compression stroke.

Engine/vehicle speed control for direct injection spark ignition engine applications

Abstract: A system and method for engine/speed control of a direct injection spark ignition engine include operating the engine in a stratified charge mode and controlling speed based on engine set points for best performance using fuel as a primary torque actuator and airflow as a secondary torque actuator whenever possible to maintain spark at or near MBT. When current operating conditions and/or system constraints prevent use of engine set points corresponding to best performance, speed control becomes the primary objective. Systems and methods according to the present invention improve the compromise between speed control and best performance set-point objectives.

Fuzzy ignition timing control for a spark ignition engine

Abstract: It is well known that the optimum ignition timing, which gives the maximum brake torque (MBT) for a given engine design, varies with the rate of flame development and propagation in the cylinder. This depends, among other factors, on engine design and operating conditions, and on the properties of the air-fuel mixture. In modern engines the ignition timing is generally controlled by fixed open-loop schedules as functions of engine speed, load and coolant temperature. It is desairable that this ignition timing can be adjusted to the optimum level producing the best torque to obtain minimum fuel consumption and maximum available power. This paper presents an ignition timing control system based on fuzzy logic theory. A pressure sensor system ws developed for the determination of combustion parameters and ignition control on a Ford 1600cm3 four-cylinder engine fuelled with natural gas. Several tests were carried out in optimizing the pressure detection system. The results obtained provide important i...

Combustion and the thermodynamic performance of spark ignition engines

Abstract: Some overall considerations for the optimization of the energy chain for the spark ignition engine are briefly discussed and figures given for the relative inhaled energies with different fuels. There follows a description of the nature of turbulent flame propagation in engines, showing the computed characteristics of the burning rate for stoichiometric and lean mixtures at different engine speeds. These reveal the factors influencing partial quenching and misfire. Flame instabilities are shown theoretically to become more important with increasing pressure. The associated flame wrinkling and cellularity increase the burning rate of both laminar and turbulent gaseous flames. Fundamental aspects of the present trend towards the direct injection of gasoline are discussed and the unique instabilities in aerosol combustion are shown to increase the burning velocity above that of the corresponding gaseous mixture. The degree to which evaporative cooling of droplets can enhance the volumetric efficiency is discussed. The onset of autoignition in an engine is calculated with recent shock tube data, which are also used to show that evaporative cooling can increase the knock resistance by about four octane numbers.

Synchronization of Combustion Variations in a Multicylinder Spark Ignition Engine

Abstract: : We report experimental observations of synchronization among combustion variations in different cylinders at fuel-lean conditions in an eight-cylinder spark ignition engine. Our results appear to confirm that synchronization readily occurs and that it becomes stronger as the overall equivalence ratio is reduced from stoichiometric. It also appears that the onset of synchronization is associated with bifurcation instabilities reported previously for combustion in single cylinders. We use both cross-correlation and symbolic time series analysis to quantify the apparent relationships between pairs of cylinders and multicylinder groups. Extension of a simple dynamic model for single-cylinder combustion variations to the multicylinder case appears to agree with the observations and provides a basis for further studies. The occurrence of significant cylinder-to-cylinder synchronization may have significant implications for engine diagnostics and control.

Rapid transient torque management in DISI engines

Abstract: A system and method for transient torque control of a direct injection spark ignition engine include controlling airflow and fuel flow rather than ignition timing so that spark timing may be set for best fuel economy. The system and method are particularly suited for variable cam timing or variable valve timing DISI engines where valve timing enables a sufficiently fast engine torque response to achieve transient control. The present invention may be used for torque-based speed control strategies, such as idle speed control or cruise control. The invention includes determining a maximum available airflow to determine whether a desired torque and air/fuel ratio can be achieved using airflow. Otherwise, the invention uses fuel flow control based on the maximum available air flow to provide the desired engine output torque and air/fuel ratio.