Ignition Timing Control Research Articles

Effects of N_2/CO_2 Addition on Ignition and Combustion in Homogeneous Charge Compression Ignition Engine Operated on Dimethyl Ether(HCCI, Effect of Fuel and Additives)

The control of ignition timing and combustion period over a wide range of engine speeds and loads in HCCI engine is one of the barriers to the realization of the engine. Application of exhaust gas recirculation, EGR, is thought to be a promising option to control ignition timing, to extend combustion period and to suppress knock like combustion. In this study, the effects of N_2/CO_2, major components of exhaust gas, addition on the heat release of cool flame and the emission characteristics of CO were investigated from experiments and computations. The heat release of cool flame was reduced with N_2 addition, however, it increased with CO_2 addition. From the systematic experiments and chemical kinetic computations, it was confirmed that the amount of heat release at cool flame depends strongly on the concentration of O_2 at cool flame onset. The dominant path for CO oxidation is the reaction of CO + OH = CO_2 + H. The produced H atoms react with O_2 molecules and produce OH + O or HO_2. The CO oxidation becomes active as increasing the blanching rate to OH + O. However, with the addition of CO_2 to the mixture, the branching rate to HO_2 was increased, resulting in a higher CO emission. Though the addition of CO_2 is effective in suppressing a knocking from its large heat capacity, it has an inferior effect on CO emission.

Validation of Retarding Mechanism in Ignition Timing of HCCI Engine by Adding Methanol to DME

Controlling ignition timing in Homogenous Charge Compression Ignition (HCCI) of Dimethyl Ether by adding methanol has been studied in a motored engine. Reduction of heat release at cool flame and consequent delay of ignition timing with the methanol addition were confirmed. In exhaust gas analysis conducted mainly in single cool flame condition, fuel consumption decreases and formaldehyde formation increases with increasing methanol addition. It was found that these functions are independent of equivalence ratio when the three variables are expressed relative to initial fuel load. These behaviors were well reproduced by simulations using Curran's mechanism, whereas a small extent of underestimation of the cool flame heat release was suggested. A simplified model accounting for the additive effect was constructed by extracting the essential chemical mechanism, in which HCHO+OH and methanol +OH reactions are responsible for the termination of the chain reaction mechanism of DME low temperature oxidation.

Advanced/Retarded Criterion on Ignition of Fuel/Air Mixtures with Formaldehyde Doping(HCCI, Effect of Fuel and Additives)

Formaldehyde artificially added into the mixtures is efficacious as an ignition control medium for hydrocarbon fuels in engine cylinders. The vapor added into the mixtures has given the premixed compression-ignition (HCCI) engine a stable ignition timing, which is controllable to get the MET by the amount of formaldehyde to be added. The effect of formaldehyde addition is either suppressing or promoting. A universal criterion of the formaldehyde effect resulting whether in the advanced or in the retarded hot-flame appearance from the original ignition events has been elucidated through experiments over a wide range of parameters on the fuel octane or butane rating, the equivalence ratio of the mixture, and the mixture temperature to be raised. The formaldehyde would be a suppressing additive under the cool-flame generating constituents, temperature and pressure conditions, and a promoting additive under the poor cool-flame generating conditions in the cylinder charge during the preflame reactions leading to the ignition. The added formaldehyde is superfluous to the ignition event originally belonging to the cool-flame dominant regime, which would give a suppressing effect. On the other hand, the artificially added formaldehyde could be a starting point of preflame reactions leading to the final hot ignition belonging to the blue-flame-dominant regime, where a few fuel transition and low intermediates appear, and where the high temperature chemistry dominates. It allows a short cut of the preflame induction period, in consequence, a promoting effect for the ignition. The low-temperature-ignition classification; three typical regime, "cool-flame dominant regime", "negative-temperature-coefficient regime" and "blue-flame dominant regime" would be a universal advanced/retarded criterion on ignition of fuel/air mixtures with formaldehyde doping for the ignition timing control in the piston compression engines.

Design of computer controlled combustion engines

Globalization and growing new markets, as well as increasing emission and fuel consumption requirements, force the car manufacturers and their suppliers to develop new engine control strategies in shorter time periods. This can mainly be reached by development tools and an integrated hardware and software environment enabling rapid implementation and testing of advanced engine control algorithms. The structure of a rapid control prototyping (RCP) system is explained, which allows fast measurement signal evaluation, and rapid prototyping of advanced engine control algorithms. A hardware-in-the-loop simulator for diesel engine control design is illustrated, simulation results for a 40 tons truck are presented. Providing efficient engine models for the proposed development tools, a dynamic local linear neural network approach is explained and applied for modelling the NO x emission characteristics of a 1.9 l direct injection diesel engine. Furthermore the application of a RCP system is exemplified by the application of combustion pressure based closed-loop ignition timing control for a SI engine. Experimental results are shown for a 1.0 l SI engine on a dynamic engine test stand.

Smokeless and low NOx combustion in a dual-fuel diesel engine with induced natural gas as the main fuel

In a compression ignition engine, using a rich and lean biform mixture composition that avoids both slightly lean and extremely over-rich regions would be effective in suppressing NOx formation without increasing smoke when the overall air-fuel ratio approaches the stoichiometric ratio. To realize the formation of rich and lean mixtures and the control of ignition timing, a dual-fuel diesel engine with an induced gas with resistance to self-ignition as the main fuel and with a small quantity of diesel fuel for the ignition source has potential merits. However, this method has the problem of knocking and misfiring when the percentage of inducted fuel is increased. In this research smokeless and very low NOx combustion without knocking over a wide operating range was established in a single-cylinder dual-fuel diesel engine with induced natural gas as the main fuel. Optimizations of the combustion chamber shape and operating factors, including exhaust gas recirculation (EGR) and intake air throttling, which determine conditions of the in-cylinder gas, were investigated at several i.m.e.p. (indicated mean effective pressure) conditions. The results of the experiments showed that a combination of the divided cavity, EGR and intake air throttling was effective in simultaneously eliminating knocking and reducing total hydrocarbon (THC) and NOx over a wide i.m.e.p. range. At high i.m.e.p. silent and smooth combustion without knocking was achieved, even with a large amount of induced natural gas. Moreover, the maximum i.m.e.p. increased in comparison with conventional diesel operation with a lower injection pressure system because smoke emission was not a limitation. At medium i.m.e.p. it was effective to adopt EGR and intake air throttling for very low NOx under relatively lower THC. However, at low i.m.e.p. it was difficult to avoid increases in THC and i.s.e.c. (indicated specific energy consumption) while realizing very low NOx and smokeless operation. At lower overall excess air ratio conditions, NOx reduction was shown with a biform mixture composition without slightly lean or extremely rich regions.

Control of Ignition and Combustion of Dimethyl Ether in Homogeneous Charge Compression Ignition Engine.

A homogeneous charge compression ignition (HCCI) engine is known to have high thermal efficiency and low nitrogen oxide emission. However, the control of ignition timing and its combustion period over a wide range of engine speeds and loads is one of the barriers to the realization of the engine. On the lean side of the equivalence ratio, control of ignition is difficult due to its long delay of ignition, and there is knocklike problem under high load. In both computations and experiments of HCCI engine operated on dimethyl ether, the operable range (the possible range of fuel input from just ignitable to knock-occurring state) shifted to the rich side with decreasing intake temperature and amount of mixing of carbon dioxide. The range of fuel input was reduced at low intake temperatures, because the hot flame onset angle advanced more quickly than it did at high intake temperatures. However, the mixing of CO2 caused the operable range to shift to the rich side while retaining the same range. The results of this study indicated the possibility of high-load operation or extension of the load range by exhaust gas recirculation.

Combustion Control and Operating Range Expansion with Direct Methanol Injection in a Premixed Charge Compression Ignition Engine

The control of ignition timing, the suppression of rapid combustion, and the expansion of stable operating range upto higher load maintaining ultra low NOx and smokeless combustion were achieved by direct methanol injection in a premixed charge compression ignition engine. The combustion suppression effect increased with advancing methanol injection timing as the methanol widely distributed in combustion chamber. With increasing in methanol injection amount, the onset of low temperature oxidation delayed and the heat release in the low temperature oxidation decreased. This reduction of low temperature oxidation resulted in suppression of the temperature rise before the onset of high temperature oxidation, then delayed the onset of high temperature oxidation, and suppressed the rapid combustion. At high load the fraction of methanol injection amount have to be more than 50% to achieve normal combustion without too early ignition and knocking. Flame luminosities during the low and high temperature oxidations decreased with methanol injection.

806 火花放電がない 2 サイクル圧縮自着火機関を用いた着火時期制御の研究

In this research, the study of ignition timing control, resulting from the application of a certain level of internal EGR, on combustion was investigated using a two-cycle engine and gasoline as the test fuel. Measurements were made of the ion current, the cylinder pressure and the combustion chamber inner wall temperature. Data were measured and analyzed on SI (Spark-Ignition) operation and AI (Auto-Ignition) operation.

Ignition timing control of homogeneous charge compression ignition engines by pulsed flame jets

In diesel engines, most of the fuel is burned in a diffusion combustion phase, which inherently leads to the formation of excessive amounts of soot and NOx emissions. In order to decrease soot and NOx emissions simultaneously, the concept of a lean homogeneous charge compression ignition engine has been proposed. The onset of the combustion of the engine depends on the autoignition of the fuel, so it is quite difficult to control the ignition timing. On the other hand, it has been revealed that Pulsed Flame Jet (PFJ) has a great potential to enhance ignition reliability and burning rate in lean mixtures. In this article, autoignition characteristics of n -butane/air mixtures in a rapid compression machine (RCM) were shown first. The appearance of low temperature flames was observed in autoignition of n -butane in the RCM used here, and it was realized that the final compression conditions in the RCM correspond to the upper end of the low-temperature range of the positive temperature dependence region of ignition delay. Then the combustion tests with PFJ were carried out and it was demonstrated that the onset of combustion can be controlled by PFJ, and it was revealed that PFJ has a potential for the ignition timing control of the homogeneous charge compression ignition engine.

A Study of Ignition Timing Controlon on Premixed Lean DI Compression Ignition Engine.

Recently, pre-mixed lean combustion has gained the attention of many researchers, who are investigating compression ignition characteristics of this type of mixture. Previous research in our laboratory has shown that low NOx combustion can be obtained by PREDIC (PREmixed lean DIesel Combustion). While NOx emissions were very good, the fuel consumption was greater than that of a conventional engine, due to a lack of ignition timing control. So in this study, ignition timing control was attempted using two fuels. Results showed that ignition timing control was possible using a low cetane fuel (such as methanol or α-methyl naphthalene) after the diesel fuel main injection. The injection timing and quantity of methanol affected the ignition timing of PREDIC.

A Study of Adequate Spray Formation for Premixed Lean Diesel Combustion. An Analysis of Impingement Spray.

Premixed lean diesel combustion (PREDIC) achieves very low NOx emissions as a result of early fuel injection. Another consequence of such early injection is an increase in the amount of fuel spray reaching the cylinder wall. This results in higher fuel consumption and THC emissions. Another shortfall is that compression ignition timing control is difficult because of its dependence upon the incylinder temperature. These problems can be addressed by utilizing an impingement spray, with two nozzles. In this study, this type of spray was analyzed on spray position control, larger spray volume, and less wall wetting, among others. Also, the impingement spray structure was analyzed by cross-sectional observation using laser induced fluorescence. Spray penetration, high-density area, and plume area were measured. The impinging sprays enhance each other's spreading and mixture formation. Higher injection pressure has little effect on spray penetration and high-density area.

Fuzzy neural ignition timing control for a natural gas fuelled spark ignition engine

One of the important inputs to a spark ignition engine which affects nearly all engine outputs is ignition timing. It is well known that the optimum ignition timing which gives the maximum brake torque for a given engine design varies with the rate of flame development and propagation in the cylinder. Modern engines show ignition timing being generally controlled by fixed open-loop schedules as functions of engine speed and load. It is desirable that this ignition timing can be adjusted to the optimum level which produces the best torque to obtain minimum fuel consumption and maximum available power. This paper presents an ignition timing control system based on fuzzy logic and neural network theories. A fibre optical sensor system was developed for measurement of the intensity of the luminous emission which correlates the combustion pressure and ignition timing control on a Ford 1600 cm3 four-cylinder spark ignition engine fuelled with natural gas. Several engine tests were carried out in optimizing the combustion intensity detection system. The results obtained provide important information compatible with intelligent control of the engine using fuzzy neural control technology. Moreover, tests carried out with data using this technology show good results that fit quite well with the original engine output torque characteristics.

An investigation of optimum control of ignition timing and injection system in an in-cylinder injection type hydrogen fueled engine

It is already known that the emission characteristic of hydrogen fueled engines are extremely good, when running the engine under lean burn conditions, with excess air ratios λ>2 which lower the NO x emissions (Int. J. Hydrogen Energy 4 (1997) 423). However, there are abnormal combustion in the engine, which is one of the factors that has prevented the practical use of the engine. It is also a common conclusion that abnormal combustion can be suppressed in the in-cylinder injection type engine (International Fuels and Lubricants Meeting and Exposition, Philadelphia, PA, 6–9 October, SAE Technical Paper Series No. 8615769, 1986; Int. J. Hydrogen Energy 2 (1977) 329). But, such advantages as suppression of abnormal combustion, engine power-up and reduction of NO x emission are gained depending on proper injection system and reasonable injection timing, ignition timing and law of hydrogen injection. In this study, Hydrogen is injected into the cylinder in the late compression stroke and is ignited by electric spark in a test engine. The research on the performance of hydrogen fueled engine is carried out under the condition of different ignition timing and injection timing. Further, a control system consisting of a fuzzy-neural network controller combining with ignition adaptive controller is applied to the engine in order to optimally control ignition timing, injection timing and cycle amount of hydrogen injection. Thus, the performances in the hydrogen engine attain optimization in every operating state of the engine.

Design of Computer Controlled Combustion Engines

Globalization and growing new markets, as well as increasing emission and fuel consumption requirements force the car manufacturers and their suppliers to develop new engine control strategies in shorter time periods. This can mainly be reached by development tools and an integrated hardware and software environment enabling rapid implementation and testing of advanced engine control algorithms.The structure of a Rapid Control Prototyping (RCP) system is explained, which allows fastmeasurement signal evaluation, and rapid prototyping of advanced engine control algorithms. A hardware-in-the-Ioop simulator for Diesel engine control design is illustrated, simulation results for a 40 tons truck are presented. Providing efficient engine models for the proposed development tools, a dynamic local linear neural network approach is explained and appliedfor modelling the NOx emission characteristics of a 1.9 liter direct injection Diesel engine. Furthermore the application of a RCP system is exemplified by the application of combustion pressure based closed-loop ignition timing control for a SI engine. Experimental results are shown for a 1.0 liter SI engine on a dynamic engine test stand.

A Study of Ignition Characteristic on Premixed Lean DI Diesel Engine.

Recently, pre-mixed lean mixture combustion has attracted attention, and many researchers are investigating compression ignition of a pre-mixed lean mixture. Previous research in our laboratory has shown that low NOx emission combustion is obtained by PREDIC (PREmixed lean Dlesel Combustion) . However some problems still remain, such as higher fuel consumption because of lack of ignition timing control, compared to conventional diesel combustion. So in this study the ignition ; characteristic was researched. As the result, it was cleared that the ignition timing was depended on the cylinder gas temperature and the ignitability of the fuel.

Gas sampling analysis of combustion processes in a homogeneous charge compression ignition engine

In-cylinder gas sampling experiments were conducted to clarify the chemical reaction processes of homogeneous charge compression ignition (HCCI) combustion. To study the differences in ignition processes by the ignitability of fuels, three kinds of straight-chain saturated hydrocarbons, such as n-pentane, n-hexane and n-heptane, were used as the fuels. Also, to study specific differences in the ignition processes between a single-component fuel and a dual-component fuel, n-pentane was used as the single-component fuel and n-hexane and ethylene, with compositions adjusted in order to have the same ignitability as n-pentane, were used as the dual-component fuel. The results show that the chemical processes in the low-temperature oxidation range, from 700 to 900 K, need to be controlled for the ignition timing control of HCCI combustion. Controlling ignition timing by dual fuel means controlling the oxidation starting time by the ignitability of a high cetane number fuel and controlling the low-temperature oxidation rate by varying the composition of the high and low cetane number fuels.

Fuzzy ignition timing control for a spark ignition engine

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 information compatible with intelligent control of the engine using fuzzy logic technology. Moreover, tests carried out to date using this technology show good results that fit quite well with the original engine output torque characteristics.

814 予混合圧縮着火機関の着火時期制御 : パルスジェットによる着火時期制御の試み(O.S.5-4 噴射制御)(O.S.5 次世代エンジンのための燃焼制御と新技術)

814 予混合圧縮着火機関の着火時期制御 : パルスジェットによる着火時期制御の試み(O.S.5-4 噴射制御)(O.S.5 次世代エンジンのための燃焼制御と新技術)

Premixed Lean Diesel Combustion Charasteristics on Supercharged Diesel Engine.

Recently, pre-mixed lean mixture combustion has attracted attention, and many researchers are investigating compression ignition of a pre-mixed lean mixture. Previous research in our laboratory has shown that low NOx emission combustion is obtained by PREDIC (PREmixed lean DIese1 Combustion). However some problems still remain, such as higher fuel consumption, a lack of ignition timing control, a large increase in THC and CO, compared to conventional diesel combustion. The output limit of PREDIC is about 50% of conventional diesel combustion. So in order to increase the PREDIC engine output, supercharging was adopted. It was resulted that the power output was higher and the fuel consumption was better than the conventional natural aspiration diesel engine using supercharging. The numerical simulation analysis shows that NOx was produced at rich mixture area because of lower spray penetration under high density conditions. As the result, the high injection rate is effective to make a lean mixture.

4844026 Spark ignition timing control system for internal combustion engine with feature of suppression of jerking during engine acceleration

4844026 Spark ignition timing control system for internal combustion engine with feature of suppression of jerking during engine acceleration