点火提前角的影响因素及其控制

对于现代汽车而言,最佳的点火提前角不仅要保证发动机的动力性和燃油经济性都达到最佳值,还必须保证排放性最好.介绍了点火提前角影响因素,提出了对点火提前角进行控制的方法,从而使发动机的动力性和经济性达到最优.     

基于GT-POWER的汽油机燃烧乙醇汽油点火正时分析

根据点火提前角数学模型,对汽油机燃烧乙醇汽油后的点火提前角进行了计算,将计算值输入到GT-POWER模型中,运行后与实验值进行对比分析,得出汽油机燃烧乙醇汽油后点火提前角应相应的减小的结论,为汽油机使用乙醇汽油后点火提前角的调整提供理论依据.     

基于BP神经网络控制天然气发动机点火提前角

点火提前角控制是天然气发动机控制的最重要内容之一,精确控制点火提前角涉及到发动机运行的动力性和经济性。对此,开发采用BP神经网络控制的方法来实现天然气发动机的点火提前角控制问题,并基于发动机平均值模型进行了神经网络的MATLAB在线仿真。结果表明:点火提前角最大绝对误差0.4°CA,最大相对误差1.5%,该优化控制模型能准确地获取天然气发动机最佳点火提前角。     

影响发动机最佳点火提前角因素的对比分析

发动机点火提前角影响汽车发动机的动力性、经济性、排放等性能指标,为加深对最佳点火提前角受相关因素影响的理解,本文对发动机最佳点火提前角的影响因素进行了梳理与分析。     

虚拟仪器技术在点火提前角测量中的应用

介绍了用笔记本计算机、信号调理电路以及数据采集卡DAQ-6024E构成的基于虚拟仪器技术的汽油发动机点火提前角测试系统。测试信号可以从发动机直接引出，经过信号调理和信号合成电路后进入数据采集卡。系统软件用图形化编程语言LabVIEW设计，测试结果可以直观地在计算机屏幕上显示。系统能测量点火提前角，显示、存储多缸的测量值，非正常工况下报警等功能。各测量参数均以博世综合测试系统和元征X431ECU诊断盒的测量值为参照。     

LNG发动机最佳点火提前角的模拟优化仿真

在某系列天然气发动机点火控制系统基础上,提出利用神经网络在线优化点火提前角,从而解决天然气发动机在使用过程中因磨损、老化等造成最佳点火提前角发生变化的问题,达到提高天然气发动机的动力性和燃气经济性的目的。首先通过Matlab/simulink建立的LNG发动机模型,编写标定程序,得出初始点火提前角,然后设计神经网络。优化策略为在稳定工况时,利用自适应神经网络在线修正,得出实时最佳点火提前角;在工况变化较快时直接读取MAP图,得到点火提前角。最后利用GT-POWER搭建天然气发动机模型进行仿真并与实测数据进行比较。     

二冲程煤油发动机整机建模与初始点火提前角计算分析

针对二冲程汽油发动机改燃烧航空煤油后,初始点火提前角需重新标定的问题,利用GT-Power对以煤油为燃料的二冲程发动机进行整机建模。通过数值计算分析了转速、负荷、进气压力、进气温度和空燃比对点火提前角的影响,得出除转速和负荷外,进气温度对点火提前角的大小影响明显。针对不同的工况条件,充分考虑动力性而忽略经济性与排放性的前提下,通过计算获取了发动机初始点火提前角;通过仿真数据与实验结果对比验证了其一致性。     

小型航空二冲程煤油发动机小负荷试验研究

将1台点燃式二冲程气道喷射汽油机改造为缸内直喷煤油发动机,在3000r/min小负荷工况下进行了点火提前角、喷气结束角、过量空气系数对性能影响的试验研究。结果表明,喷气结束角为50°和80°（上止点前）时,适当增大点火提前角,能使功率增加、油耗降低,但点火提前角不宜过大,否则会造成HC和CO排放量的增加;点火提前角为15°和30°（上止点前）时,适度提前喷气结束时刻,可以使功率增加、油耗和排放降低;另外,偏浓混合气有利于提高功率输出,偏稀混合气有利于降低排放。     

用点火正时仪 检测燃气发动机点火提前角

12V190型燃气发动机采用火花塞点火,其点火提前角是否准确直接影响发动机的动力性和燃油经济性。     

点火角对小排量增压汽油机燃烧特性的影响研究

对465Q汽油机进行废气涡轮增压改造,研究点火角对增压后发动机燃烧特性的影响。随点火角的增大,缸内最高压力和压升率峰值都增大,其对应的曲轴转角提前,燃烧循环变动改善;每个工况下,都存在一个最佳的点火角,使发动机的功率最大,燃油消耗率最低。在最佳点火角附近,点火角每调整5°,动力性和经济性变动幅度在4%左右。     

Effect of spark plug protrusion on the performance and emission characteristics of an engine fueled by hydrogen-natural gas blends

Mixtures of hydrogen and natural gas are promising for improving efficiency and reducing harmful emissions in spark ignition engines, since limits of flammability can be extended while stable combustion is secured. In this research, the combustion characteristics of long electrode spark plugs were evaluated in a hydrogen blended with natural gas (HCNG) engine. Decreases in the flame propagation distance through the use of spark plugs can lead to increased burning rates and further improvement of fuel economy in HCNG engines. An 11-liter heavy duty lean burn engine was employed and performance characteristics including emissions were assessed according to the spark timing of the minimum advance for best torque (MBT) for each operating condition. Retarded MBT spark advance timing with long electrode spark plugs due to increased burning speed supported increases in engine efficiency and reductions of nitrogen oxide (NO_x) emissions. The lower positions of initial flame kernels due to the use of long electrode spark plugs were preferable to improvements of cyclic variability due to reduced flame front quenching, and carbon monoxide (CO) emissions at the flammability limit were also improved.     

PVDF振动传感器的设计及在点火发动机中的应用

聚偏氟乙烯（PVDF）是一种新型压电高分子材料，它具有独特的压电效应，已被越来越广泛地应用于振动控制领域。通过余弦形状的PVDF薄片，设计出具有紧凑结构的振动传感器，并设计了实用的电荷放大电路，最后用其来检测发动机的爆震点，从而对发动机点火提前角进行控制，使发动机工作在轻微爆震状态，通过实验表明PVDF振动传感器测量简单、更方便、更准确，经济性和动力性得到了提高。     

并联混合动力轿车多能源管理系统标定试验

介绍基于超级电容的单轴并联混合动力轿车结构,开发出混合动力多能源管理系统,实现了发动机管理系统与整车管理系统的软件和硬件集成化.在测功机上对发动机进行了稳态标定,得到发动机的万有特性、基本点火提前角、充气效率和比油耗等数据.整车转鼓试验表明,采用电子节气门和燃油瞬态补偿策略的混合动力汽车排放较低,能够达到国Ⅲ和国Ⅳ的排放标准.将发动机的喷油转速提高到1.2 kr/min, 避免了传统发动机在低转速下的过浓喷油,并且取消了发动机的怠速工况,将混合动力汽车的油耗降低8%～10%.通过对起动过程空燃比和点火提前角的优化,缩短了三效催化转化器的起燃时间,降低了发动机的冷起动排放.这种硬件和软件集成的设计结构,降低了研发成本,推进了混合动力产业化进程.     

5kW沼气发电机的研究与开发

为了合理利用丰富的沼气资源,将5kW汽油发电机改装成可以燃用沼气的燃气发电机,并设计了水容式阻火器、稳压减压器等安全设施;对改装后的燃气机采取了提高压缩比、增大点火提前角、采用高能点火等优化改进措施,并对发电机燃用汽油和沼气进行了性能对比试验。试验结果表明：该系统能够安全可靠地工作,机组燃沼气时排放比燃汽油时得到明显改善,有效燃料消耗降低,经济性更好。     

Effects of various intake valve timings and spark timings on combustion,cyclic THC and NOX emissions during cold start phase with idle operation in CVVT engine

In a gasoline SI engine, valve events and spark timings put forth a major influence on overall efficiency, fuel economy, and exhaust emissions. Residual gases controlled by the valve overlap can be used to reduce NOx emissions and the spark retardation technique can be used to improve raw THC emissions and catalyst light-off performance during the cold start phase. This paper investigated the behaviors of the engine and its combustion characteristics with various intake valve timings and spark timings during the fast idle condition and cold start. And cyclic THC and NOx emissions were measured at the exhaust port and their formation mechanisms were examined with fast response gas analyzers. As a result, THCs and NOx were reduced by 35% and 23% with optimizing valve overlap and spark advance during the cold transient start phase. Consequently, the valve events and ignition timings were found to significantly affect combustion phenomena and cold-start emissions. This paper was recommended for publication in revised form by Associate Editor Kyoung Doug Min Simsoo Park received his B.S. and M.S. degrees from Seoul National University in 1977 and 1979, respectively, and a Ph.D. from the State University of New York at Stony Brook. He served as a Principle Research Engineer at Hyundai Motor Company, a Director for Publication of the KSME, a Technical Advisor of Hyundai-Kia Motor Company, and an Editing Director, Project Director, International Director, Accounting Director, and General Affair Director of KSAE. He is currently Vice President of Editing and International at KSAE and a professor of mechanical engineering at Korea University.     

Ignition Pattern Analysis for Automotive Engine Trouble Diagnosis Using Wavelet Packet Transform and Support Vector Machines

Engine spark ignition is an important source for diagnosis of engine faults.Based on the waveform of the ignition pattern,a mechanic can guess what may be the potential malfunctioning parts of an engine with his/her experience and handbooks.However,this manual diagnostic method is imprecise because many spark ignition patterns are very similar.Therefore,a diagnosis needs many trials to identify the malfunctioning parts.Meanwhile the mechanic needs to disassemble and assemble the engine parts for verification.To tackle this problem,an intelligent diagnosis system was established based on ignition patterns.First,the captured patterns were normalized and compressed.Then wavelet packet transform(WPT) was employed to extract the representative features of the ignition patterns.Finally,a classification system was constructed by using multi-class support vector machines(SVM) and the extracted features.The classification system can intelligently classify the most likely engine fault so as to reduce the number of diagnosis trials.Experimental results show that SVM produces higher diagnosis accuracy than the traditional multilayer feedforward neural network.This is the first trial on the combination of WPT and SVM to analyze ignition patterns and diagnose automotive engines.     

Performance and emission characteristics of a low heat rejection spark ignited engine fuelled with E20

In internal combustion engines, the concept of low heat rejection (LHR) using thermal barrier coating on the surface of combustion chamber is gaining attention. Thermal barrier coating reduces the heat transfer to the cooling system, protects engine components from peak heat flux and fluctuating temperature produced during combustion and improves the performance of the engine. Information in the literature is plentiful for LHR diesel engine and only few studies exist on LHR spark ignited engine. The application of thermal barrier coating in spark ignited engine is limited by pre-ignition and knocking due to elevated combustion chamber temperature. A spark ignited engine with moderate insulation on the combustion chamber and higher octane fuel can overcome this difficulty. The objective of the present experimental study is to quantify the changes in performance and emission characteristics brought by partial thermal insulation on the combustion chamber of a four stroke spark ignited engine fueled with E20 blend. Partial thermal insulation was created by coating 0.3 mm thick Alumina (Al₂O₃) on the cylinder head, inlet and exhaust valves. The changes are quantified with respect to unmodified engine fueled with gasoline. The combustion parameters such as flame development and rapid burn duration are also estimated and compared. The results indicate that partially insulated SI engine when fueled with E20 improves performance and reduces emission. A maximum of 48% reduction in THC and 50% reduction in CO emission at part load was achieved.

     

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。     

Cycle-to-cycle variations under cylinder-pressure-based combustion analysis in spark ignition engines

Combustion analysis based on cylinder-pressure provides a mechanism through which a combustion researcher can understand the combustion process. The objective of this paper was to identify the most significant sources of cycle-to-cycle combustion variability in a spark ignition engine at idle. To analyse the cyclic variation in a test engine, the burn parameters are determined on a cycle-to-cycle basis through the analysis of the engine pressure data. The burn rate analysis program was used here and the burn parameters were used to determine the variations in the input parameter—i, e,, fuel, air, and residual mass. In this study, we investigated the relationship of indicated mean effective pressure (IMEP), coefficient of variation (COV) of IMEP, burn angles, and lowest normalized value (LNV) in a spark ignition engine in a view of cyclic variations.