电喷汽油发动机起动困难故障诊断方法

起动困难是电喷汽油发动机的常见故障,因为无论发动机处于冷态还是热态,都有着较为苛刻的起动条件,例如对发动机的空燃比、点火时刻以及点火能量等都有一定的要求,而且对蓄电池电压和起动机的转速等也有要求.因此对于电喷汽油发动机起动困难的故障要根据其故障现象和容易引起这些故障现象的相关因素进行分析和排除.结合实例详细阐述了常规的故障诊断和排除方法并提供了完善的诊断流程.     

火花塞积炭的影响因素及对策

自主品牌的新车型在冬季普遍遇到冷起动和火花塞积炭问题,尤其是配备增压发动机或增压直喷发动机的车辆,冷起动和火花塞积炭问题更加突出。从系统的角度分析积炭的影响因素,并指出:改善火花塞积炭问题,核心是做好整车的冷起动ECU数据标定和冷起动试验,尤其是低温大负荷条件下发动机喷油相位、喷油量和点火正时参数之间的合理搭配;在系统无法再优化的前提下,优化火花塞点火端的结构设计可以改善冷起动和积炭问题;良好的驾驶习惯、定期维护点火系统、使用符合国家规范的燃油,也可以改善冷起动和积炭问题。     

煤油发动机冷起动缸盖预热方法研究

活塞发动机燃烧煤油时,预热是解决冷起动困难的有效方法之一。本文提出了煤油发动机缸盖预热的方法,讨论了两种加热片在缸盖上的布片方式,利用Fluent对每种布片方式的温度场进行了仿真计算。进行煤油发动机冷起动试验,在不改动发动机喷油和点火系统的条件下,对两种布片方式进行了试验验证,通过比较预热时间,得到预热效果较好的布片方式,并证明煤油发动机冷起动性能得到了较大改善。     

基于欧Ⅲ标准的某型号汽油机稳态排放特性试验研究

编制了欧Ⅲ标准常温下“冷起动后排气排放试验”程序,在某型号汽油发动机的各种稳态工况下,测得不同点火提前角和空燃比条件下运行时尾气中的一氧化碳（CO）、碳氢化合物（HC）、氮氧化物（NOx）的排放特性。通过试验分析了各种运转参数对汽油机尾气排放特性的影响关系,为综合匹配各运转参数来达到降低车用汽油发动机尾气排放奠定了基础。     

基于欧Ⅲ标准的某型号汔油机稳态排放特性试验研究

编制了欧Ⅲ标准常温下"冷起动后排气排放试验"程序,在某型号汽油发动机的各种稳态工况下,测得不同点火提前角和空燃比条件下运行时尾气中的一氧化碳(CO)、碳氢化舍物(HC)、氮氧化物(NOx)的排放特性.通过试验分析了各种运转参数对汽油机尾气排放特性的影响关系,为综合匹配各运转参数来达到降低车用汽油发动机尾气排放奠定了基础.     

被动预燃室发动机低温冷起动及低负荷试验研究

预燃室射流点火是改善汽油发动机热效率的有效手段,为了研究和改善被动预燃室低温冷起动及低负荷时的燃烧稳定性,设计了不同容积、孔面积、材料、喷孔结构的被动预燃室装置,安装在一台涡轮增压汽油发动机上,进行了低温冷起动试验,以及低速、低负荷燃烧稳定性试验。研究结果表明,被动预燃室容积、孔面积、材料、喷孔结构对低温冷起动性能有显著影响。预燃室容积较小时,预燃室内部淬熄层占预燃室容积的比例大,预燃室内部混合气少。较小的孔径或孔面积减少了预燃室内残余废气的排出。旋转孔使得预燃室内部废气分层,火花塞附近废气比例大。较高的导热率使预燃室冷起动时预燃室散热较快。因此,小容积、小孔径、高导热率材料以及旋转喷孔等均不利于发动机冷起动。优化结构的被动预燃室在-20℃～-8℃的冷起动工况下能实现发动机稳定着火起动。点火角和排气VVT对发动机的燃烧稳定性影响较小。进气VVT对预燃室燃烧稳定性影响较大,进气门开起时刻推迟,着火上止点附近缸内湍动能变强;另一方面实际压缩比变大,主燃烧压入预燃室内部的新鲜混合气比例提高,预燃室点火燃烧稳定性显著改善。     

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。     

电喷汽油机使用乙醇汽油的试验研究

在电喷汽油机参数耒作任何调整的情况下,试验研究了燃用乙醇汽油对发动机动力性和经济性的影响.研究表明:电喷汽油机改燃乙醇汽油后,全负荷时汽油机动力输出不变;但部分负荷时,动力输出稍微有所下降;与普通汽油相比,乙醇汽油的燃油消耗率有所增加;在怠速工况下.汽油机的CO、HC等废气排放有显著降低.     

某型柴油机高压共轨系统冷起动性能试验研究

以某非道路用国产高压共轨系统柴油机为研究对象,对其冷起动性能进行研究,并与带国外高压共轨喷油器的同款发动机进行对比,通过分析冷起动试验结果,对国产高压共轨ECU里喷油参数进行优化标定。最终通过试验验证,使国产高压共轨柴油机冷起动性能特别是排放性得到极大地改善。     

现代汽油机基于点火能量的点火系统研究

以点火能量为线索,对现代汽油机点火系统主要零部件的功能特点进行分析和阐述;简述了点火系统零部件的原理以及其对点火能量的影响。电控点火系统的有效匹配可使发动机的动力性、经济性和排放得到改善。     

Experimental study of fine center electrode spark plug in bi-fuel engines

In the present work, the erosion of platinum fine center electrode spark plugs and conventional nickel plugs are investigated in a gasoline and natural gas bi-fuel engine. The effect of electrode erosion is evaluated by comparing the required ignition voltage and cold start ability of the different plug designs. After durability tests, platinum fine center electrode plug had insignificant electrode erosion and negligible gap growth; whereas the nickel plug had notable erosion and gap growth. There was no detectable side sparking for fine center electrode plugs. In terms of performance, the required ignition voltage of fine center electrode plug was lower than conventional spark plug. Also, results of a cold start test demonstrated that the starting time of the engine with fine electrode plugs was lower than conventional spark plugs. The surface of electrodes was studied by the scanning electron microscope and the energy dispersive X-ray spectroscopy techniques. Cracking and peeling was observed on the surface of the nickel conventional electrodes, but not on the surface of the platinum fine electrodes. These tests show that platinum fine center electrodes could be suitable for gasoline/natural gas bi-fuel engines to meet long lifetime demand.     

LJ465Q-2AE1汽油机满足欧Ⅲ排放标准的研究

LJ465Q-2AE1发动机是新研制开发达到欧Ⅲ排放要求的汽油机,它具有结构紧凑、升功率大、油耗低、转速高、噪声小等特点。笔者介绍了如何对该汽油机的燃烧系统、进气系统、点火系统及排气催化转化系统进行的优化设计。     

Control of cold start hydrocarbon emissions of motor bike engine by gasoline-ethanol blends and intake air heating

Two wheeled motor bikes are playing an important role in urban passenger transportation owing to ease of handling and affordable cost. Maximum amount of unburnt hydrocarbons (HC) and carbon monoxide (CO) are emitted during cold start of spark ignition engines. The current work presents the possible reduction of cold start HC emissions of 150 CC motorbike spark ignition (SI) engine with ethanolgasoline blends and/or with intake air heating by glow plug. Anhydrous ethanol was blended with unleaded gasoline in the range of 0% (E0) to 20% (E20) by volume to be used as fuel. The experimented parameters were intake air temperature, exhaust gas temperature, fuel consumption and exhaust gas emissions. Without intake air heating, E10 was found to be the optimum to reduce the cold start HC emissions by 23%. With intake air heating in the range of 40°C to 70°C, maximum HC emissions reduction was 23.8% for neat gasoline at 50°C and 33.6% for E10 blend at 60°C.     

A study on characteristics and control strategies of cold start operation for improvement of harmful exhaust emissions in SI engines

Emission regulations for automobiles have become more stringent and the improvement of emission during cold start has been a major key issue to meet these regulations. Among many kinds of factors that affect cold start operation, ignition timing is crucial to improve emission characteristics due to the influence on exhaust gas temperature. Recent progress in variable valve timing allows optimized valve event strategies under various ranges of engine operating conditions including cold start. This study investigates effects of ignition and exhaust valve timing on exhaust gas temperature, combustion stability and emission characteristics through cold start bench tests of an SI engine. Experimental results show that exhaust valve timings and ignition timings significantly affect exhaust gas temperature and stability of engine operation under cold start condition. Exhaust valve timing also affects CO and NO_x emission due to changes in residual gas fraction of the combustion chamber. Ignition timing mainly affects exhaust gas temperature and HC emission. A control strategy, advanced exhaust valve timing and retarded ignition, is plausible in order to achieve reduction of exhaust emission while maintaining stability under cold start operation of SI engines.     

M15发动机性能模拟研究

采用GT-Power软件建立模型,模拟某VVT汽油机的工作过程,分析在汽油机上直接燃用M15燃料时动力性下降的原因,并以恢复原机动力性能为目标进行优化,把优化后的M15发动机与原机性能进行对比,指出优化原汽油机点火提前角可以提高M15发动机的动力性能。     

165F汽油机燃用沼气的可行性试验研究

随着石油能源的消耗量愈来愈大,而蕴藏量愈来愈少的国际能源状况,寻找发动机替代能源的要求越来越迫切。在此背景下,笔者以沼气作为小型汽油机的替代燃料,在165F汽油机上进行燃用沼气的改装实验,将原来汽油机磁电机式点火系统改成蓄电池式点火系统,通过试验得出以沼气作为小型汽油机燃料是初步可行的。     

LJ276发动机电喷化改造设计

应用GT-Power软件搭建原机模型,并进行仿真计算,计算结果与试验结果基本吻合,验证了仿真模型的准确性。针对原机化油器的不足,建立了LJ276电喷化仿真模型,模拟性能有所提高。依次对进气系统结构进行了一系列的优化设计。结果表明,改进后的汽油机的动力性、燃油经济性均得到一定的改善。制作样机进行台架试验,与原机相比,电喷发动机扭矩最大提高9．2％,功率最大提高9．2％,燃油消耗率最大降低15．4％。     

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