STUDY ON INJECTION AND IGNITION CONTROL OF GASOLINE ENGINE BASED ON BP NEURAL NETWORK

According to advantages of neural network and characteristics of operating procedures ofengine, a new strategy is rapresented on the control of fuel injection and ignition timing of gasolineengine based on improved BP network algorithm. The optimum ignition advance angle and fuelinjection pulse band of engine under different speed and load are tested for the samples trainingnetwork, focusing on the study of the design method and procedure of BP neural network in engine     

缸内直喷汽油机冷启动燃烧与排放光学试验研究

结合光学单缸机和激光诱导荧光测量技术对直喷汽油机冷怠速工况缸内油气混合与燃烧过程进行了可视化试验研究。试验采用了屋脊形透明缸套和双侧激光,利用统计图像评估方法得到了缸内混合气浓度和燃烧火焰分布图像,通过缸压传感器和燃烧分析仪对燃烧稳定性进行了分析,采用废气分析仪和光学传感器分别对碳氢和碳烟排放进行了分析评估。研究表明：燃烧稳定时燃油与缸套碰壁是碳氢排放产生的主要原因,碳烟排放则主要由活塞顶部燃油碰壁造成;适当推迟第二次喷油时刻有利于点火时刻火花塞附近稳定浓混合气的形成,继而提高燃烧稳定性,同时减少碳氢排放,过迟喷射会导致碳烟明显增加,过早喷射会造成缸内失火,碳氢排放增加。     

汽油添加剂含量对其节油和排气净化效果的影响

简述了汽油添加剂的种类和基本工作原理,在汽油机试验台架上,进行了一系列汽油中含有不同含量的MAZ添加剂在等同工况下的热车怠速、常用转速为2 800 r/m in的负荷特性和外特性对比试验,探讨新型多效燃油添加剂MAZ加到国产90#汽油中的体积分数对其节油和排气净化效果的影响。检测结果表明,汽油中含MAZ添加剂的体积分数为0.1%时,能有效改善发动机的燃油经济性和排放特性,而发动机的动力性则基本不变,其综合使用效果较佳。     

PID控制在汽油机怠速稳定性控制中的应用研究

介绍了PID控制的原理以及该理论在汽油机怠速稳定性控制中的应用;通过在标定开发中对汽油机点火角、气路的P/D控制,以及I相的综合控制,实现了发动机怠速稳定性波动小于30 min/s的工程开发要求;分析了PID各项对怠速转速稳定控制的作用及影响程度,总结了标定过程中PID的调整规则。     

An investigation on the fuel behavior for a PFI type motorcycle engine

Recently, the electrically controlled fuel injection type motorcycle has been emphasized in order to meet regulations for exhaust emissions. However, there are many difficulties in selecting the control parameters because the pulsation phenomenon occurs in the intake port due to the higher speed operating range and the smaller layout than for a passenger car. Therefore, we investigated the injector spray characteristics which are applied to a 4-valve motorcycle gasoline engine. The spray characteristics were visualized by using a CCD camera synchronized with the stroboscope at 6000 rpm. Furthermore, we compared the simulation results using the VECTIS code with experimental results. The results showed that the trajectory of the spray was directed towards the lower wall of the intake port when the fuel was injected at closed valve timing. On the other hand, when the fuel was injected at open valve timing, a large portion of the fuel was lifted towards the upper half of the port. In addition, open valve injection makes fuel evaporation time short; this resulted in better mixture formation than a closed valve injection. From this result, we found that injection timing has a great effect on the mixture formation within a motorcycle cylinder.     

Analysis of compression ignition combustion in a schnurle-type gasoline engine comparison of performance between direct injection and port injection systems-

A two-stroke Schnurle-type gasoline engine was modified to enable compression-ignition in both the port fuel injection and the in-cylinder direct injection. Using the engine, examinations of compression-ignition operation and engine performance tests were carried out. The amount of the residual gas and the in-cylinder mixture conditions were controlled by varying the valve angle rate of the exhaust valve (VAR) and the injection timing for direct injection conditions. It was found that the direct injection system is superior to the port injection system in terms of exhaust gas emissions and thermal efficiency, and that almost the same operational region of compression-ignition at medium speeds and loads was attained. Some interesting combustion characteristics, such as a shorter combustion period in higher engine speed conditions, and factors for the onset of compression-ignition were also examined.     

Design of an optimal idle speed controller for a turbocharged diesel engine using fuzzy logic method

Idle Control of Internal Combustion Engines (ICEs) is one of the most important modules of Engine Management Systems (EMS) due to its effects on fuel consumption (FC) and pollutions produced in urban traffics. PID controllers are usually used for idle speed regulation. In this paper a PID like fuzzy controller is used to control the idle speed. The aim of this research is to introduce the selection method of membership functions for nonlinear processes which have unsymmetrical behaviors around working point. Also a simple yet useful graphical base approach to optimize fuzzy like PID controller is introduced. In order to design the controller a mean value model of a 1.6 turbocharged diesel engine is applied. In this model the effects of injection timing, injected fuel mass, ambient conditions and cycle by cycle torque generation variations are taken into account. The model also predicts the engine behavior in warm-up period. Two main manipulated variables of injection timing and injected fuel mass per cycle are handled to control the engine speed under different sources of engine speed variation such as external loads made by A/C, steering hydraulic pump or alternator and also the internal loads e.g. variable internal friction. The designed controller shows high robustness in response to change in ambient conditions.     

Idle speed modeling and optimal control of a spark-ignition engine

A model of engine dynamics is developed. The model is a MISO (Multi Input Single Output) linear model which has two inputs and one output. One input is the spark timing, and the other is the ISCV (Idle Speed Control Valve) position. The output is the angular speed of an engine. The reliability of the developed model is confirmed by comparing the measured response of the engine to step inputs and external disturbance with the simulation results. In order to reduce the steady state error, an integrator state is inserted to the state equation. An engine idle speed controller is designed using optimal control theory based on the model. The performance variation of the controller to the various design parameters is simulated. On the basis of the simulation and the experimental data, the design parameters are determined. The developed controller reduced the idle speed drop caused by an external load change and recovered the desired idle speed in one second.     

Effects of piston shapes and intake flow on the behavior of fuel mixtures in a GDI engine

The purpose of this study is to investigate the stratification of fuel vapor with different in-cylinder flow, piston cavity and injection timings in an optically accessible engine. Three different piston shapes that are F(Flat), B(Bowl) and R(Re-entrance) types were used. The images of liquid and vapor fuel were captured under the motoring condition using Laser Induced Exciplex Fluorescence technique. As a result, at early injection timing of 270° BTDC, liquid fuel was evaporated faster by tumble flow than swirl flow, where most of fuel vapor were transported by tumble flow to the lower region and both sides of cylinder for the F-type piston. At late injection timing of 90° BTDC, tumble flow appears to be moving the fuel vapor to the intake side of the cylinder, while swirl flow convects the fuel vapor to the exhaust side. The concentration of mixture in the center region was highest in the B-type piston, while fuel vapor was transported to the exhaust side by swirl flow in F and Rtype pistons. At the injection timing of 60° BTDC, the R-type piston was better for stratification due to a relatively smaller bowl diameter than the others.     

Experimental study on axial stratification process and its effects (I)-Stratification in Engine-

This paper is the first of several companion papers, which investigate axial stratification process and its effects in an SI engine. The axial stratification is very sophisticate phenomenon, which results from combination of fuel injection, port and in-cylinder flow and mixing. Because of the inherent unsteady condition in the reciprocating engine, it is impossible to understand the mechanism through the analytical method. In this paper, the ports were characterized by swirl and tumble number in steady flow bench test. After this, lean misfire limit of the engines, which had different port characteristic, were investigated as a function of swirl ratio and injection timing for confirming the existence of stratification. In addition, gas fuel was used for verifying whether this phenomenon depends on bulk air motion of cylinder or on evaporation of fuel. High-speed gas sampling and analysis was also performed to estimate stratification charging effect. The results show that the AFR at the spark plug and LML are very closely related and the AFR is the results of bulk air motion.     

A study on the deposit formation in the cylinder and intake valve of a S. I. Engine

A spark ignition engine with port fuel injection (P.F.I.) system was used to accumulate cylinder head deposit (C.H.D.), intake valve deposit (I.V.D.), and piston top deposit (P.T.D.) on an engine dynamometer. In this study, the effect of base gasoline on I.V.D. was examined. The deposit forming tendency and the influence of the fuel component for decreasing deposits have been experimentally examined. The amount of I.V.D. has been observed to increase linearly with the engine operating time. It is also observed that the amount of valve deposit with newly blended gasoline is less than that with base gasoline.     

高压共轨柴油机预喷射标定试验研究

以配备Bosch第2代高压共轨燃油喷射系统的柴油机为基础,运用INCA5.4在线标定软件和ES590等,对柴油机进行了预喷射的在线标定。根据优化的喷射策略,开展了预喷射对柴油机整机性能影响的试验研究。结果表明,预喷射在柴油机怠速时可以有效降低发动机噪声,与无预喷射方式相比,有预喷射方式的燃油消耗率略有升高。     

直接起动阶段直喷汽油机运动特性的模拟

建立了直喷汽油机的三维数值模型和运动学模型,并进行了试验验证。模拟了直喷汽油机在直接起动过程中不同喷油策略和点火时刻下的燃烧特性、反转和正转过程的运动特性。结果表明：与单次喷油相比,采用两次喷油策略时,首个着火气缸内混合气燃烧后的最大气缸压力较大,而且其大小受到点火时刻的影响;首个着火气缸内混合气燃烧后的最大气缸压力较大,则直喷汽油机反转过程中转过的最大角度较大;在各种喷油条件下,第2个着火气缸在反转到其最大转角前2°左右点火,正转过程转速较高,有利于直喷汽油机的直接起动。     

Effect of water induction on the performance and exhaust emissions in a diesel engine (II)

This study was to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in an IDI diesel engine. The fuel injection timing was also controlled to investigate a method for the simultaneous reduction of smoke and NOx when water was injected into the combustion chamber. The formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water played a role as a heat sink during evaporating in the combustion chamber, while the smoke was slightly increased with increased water amount. Also, NOx emission was significantly decreased with increase in water amount. A simultaneous reduction in smoke and NOx emissions was obtained when water was injected into the combustion chamber by retarding more 2°CA of the fuel injection timing than without water injection.     

浅谈缸内直喷发动机

简要阐述了缸内直喷技术的特点和缸内直喷发动机发展前景,重点介绍了缸内直喷发动机的綦本组成、工作原理和缸内直喷发动机的优缺点等。     

某汽油机VVT系统的优化设计

发动机可变气门正时技术(VVT,Variable Valve Timing)至今已经有30余年的历史,由于其省油、功升比大等优点,近年来得到了广泛的运用。针对在汽油发动机台架试验运行过程中,某汽油机VVT工作异常进行阐述,对该故障进行分析。通过对VVT系统的优化设计及相关的试验验证,从而有效地解决了故障问题。     

A mathematical model for the prediction of the injected mass diagram of a S.I. engine gas injector

A mathematical model of gaseous fuel solenoid injector for spark ignition engine has been realized and validated through experimental data. The gas injector was studied with particular reference to the complex needle motion during the opening and closing phases, which strongly affects the amount of fuel injected. As is known, in fact, when the injector nozzle is widely open, the mass flow depends only on the fluid pressure and temperature upstream the injector: this allows one to control the injected fuel mass acting on the “injection time” (the period during which the injector solenoid is energized). This makes the correlation between the injected fuel mass and the injection time linear, except for the lower injection times, where we experimentally observed strong nonlinearities. These nonlinearities arise by the injector outflow area variation caused by the needle bounces due to impacts during the opening and closing transients [1] and may seriously compromise the mixture quality control, thus increasing both fuel consumption and pollutant emissions, above all because the S.I. catalytic conversion system has a very low efficiency for non-stoichiometric mixtures. Moreover, in recent works [2, 3] we tested the simultaneous combustion of a gaseous fuel (compressed natural gas, CNG, or liquefied petroleum gas, LPG) and gasoline in a spark ignition engine obtaining great improvement both in engine efficiency and pollutant emissions with respect to pure gasoline operation mode; this third operating mode of bi-fuel engines, called “double fuel” combustion, requires small amounts of gaseous fuel, hence forcing the injectors to work in the non-monotonic zone of the injected mass diagram, where the control on air-fuel ratio is poor. Starting from these considerations we investigated the fuel injector dynamics with the aim to improve its performance in the low injection times range. The first part of this paper deals with the realization of a mathematical model for the prediction of both the needle motion and the injected mass for choked flow condition, while the second part presents the model calibration and validation, performed by means of experimental data obtained on the engine test bed of the internal combustion engine laboratory of the University of Palermo.     

Thermodynamic model for prediction of performance and emission characteristics of SI engine fuelled by gasoline and natural gas with experimental verification

In this study, a thermodynamic cycle simulation of a conventional four-stroke SI engine has been carried out to predict the engine performance and emissions. The first law of thermodynamics has been applied to determine in-cylinder temperature and pressure as a function of crank angle. The Newton-Raphson method was used for the numerical solution of the equations. The non-differential form of equations resulted in the simplicity and ease of the solution to predict the engine performance. Two-zone model for the combustion process simulation has been used and the mass burning rate was predicted by simulating spherical propagation of the flame front. Also, temperature dependence of specific heat capacity has been considered. The performance characteristics including power, indicated specific fuel consumption, and emissions concentration of SI engine using gasoline and CNG fuels have been determined by the model. The results of the present work have been evaluated using corresponding available experimental data of an existing SI engine running on both gasoline and CNG. It has been found that the simulated results show reasonable agreement with the experimental data. Finally, parametric studies have been carried out to evaluate the effects of equivalence ratio, compression ratio and spark timing on the engine performance characteristics in order to show the capability of the model to predict of engine operation.     

车用柴油机燃烧和热流分析的数值研究

利用商用软件STAR—CD及ES—ICE对某D6114柴油机在的缸内燃烧过程进行了数值模拟计算,分析和比较了不同喷油提前角对缸内燃烧过程和燃烧室表面热流的影响。研究结果表明：喷油提前角提前,柴油机缸内的燃烧效果优于喷油提前角推迟,燃烧过程中缸内的压力和温度比推迟喷油提前角时要大,同时缸内的最高燃烧压力和最高温度也高;喷油提前角对缸盖和活塞顶壁面平均热流的影响与其对缸内平均温度的影响相似,对缸套壁面的影响是喷油提前角提前越早,传给缸套的热流越小。数值计算结果为高功率、高强化和低热损的柴油机设计提供理论依据。．     

汽油添加剂对改善发动机性能的试验研究

本文叙述了汽油添加剂的主要作用和分类,并通过发动机台架试验研究了美狮汽油添加剂对发动机经济性及排气净化的影响,试验结果表明汽油中添加体积分数为01%的美狮汽油添加剂能够改善发动机经济性及排放性能。