高压共轨喷油器测试电路设计及其检测平台开发研究

为了检测高压共轨喷油器的工作性能,改善汽车尾气的排放质量,对高压共轨喷油器的动作原理及其检测波形进行了分析,并对喷油器的喷油量进行了计算。采用PLC技术,利用PWM方法,设计了一种喷油器检测电路及其测试平台,可以检测各类型号的高压共轨喷油器在怠速及全油门状态下的喷油状况,对其喷油质量给出判定,该平台也可进行喷油嘴驱动电路的优化研究。     

基于压电效应的喷油器及其控制

基于压电效应的喷油器重量轻,响应快,灵敏度高;能够实现少量的预喷油、多次喷油,且喷油开始时刻、喷油间隔时间能够随发动机的运行工况进行柔性控制,排放可以达到欧洲Ⅳ号标准.对基于压电效应的喷油器的结构及其工作原理进行了分析,并对压电模块驱动器的工作特性进行了分析.     

喷油器与ECU匹配试验方法研究

高压共轨喷油器是高压共轨系统中的核心部件,喷油器与ECU间的匹配状态,决定喷油器的的喷油特性和动态性能,最终决定发动机的性能,因此喷油器与ECU间匹配好坏至关重要。本文主要介绍喷油器的工作原理,包含机械原理与电路驱动原理;与ECU间匹配,包含分析喷油器电器参数,离线测试,离线测试后再次进行理论评估;如何通过泵台试验进行验证,包含泵台介绍,泵台实验设计,喷油速率对比,喷油油量对比,散差对比。同时通过泵台得到的数据对发动机性能标定提供支持。     

超磁致伸缩驱动高压共轨式喷油器的结构设计及喷油特性分析

针对现有喷油器存在的喷油速率低、喷油脉宽大、响应速率慢的问题,提出了一种超磁致伸缩驱动高压共轨式喷油器的设计方案。简述了该高压共轨式喷油器的整体设计及工作原理,并且在Jiles-Atherton磁滞模型和液压传动理论基础上建立数学模型;采用COMSOL建立了驱动部分仿真模型,并进行输出位移和应力特性分析,采用AMESim建立了喷油器整体模型,并进行喷油速率分析;搭建试验平台,验证了超磁致伸缩驱动高压共轨式喷油器设计方案的有效性。结果显示：当线圈电流为3.6 A时,超磁致伸缩棒的最大输出位移可达52μm;在160 MPa的压力下喷油最低脉宽从1 ms降低到0.15 ms,并且无论脉宽长短,其脉宽-喷油量均具有良好的线性度。结果表明,提出的设计方案可行,为研制出一种高性能的高压共轨式喷油器奠定了理论和技术基础。     

电控喷油器强度的有限元计算分析

喷油器是电控喷油系统中最基本、最关键的元件之一,它接受电子控制单元（ECU）发出的控制指令,完成喷油过程,以实现满足系统要求的各种不同喷油规律。由于喷油器的工作油压很高,为保证其工作的安全性和可靠性,检验其结构参数是否合理,有必要对其进行有限元强度计算。本文采用大型CAD软件I-DEAS Master SeriesTM,对喷油器体进行了强度计算和应变分析。对喷油器的结构参数和材料选择进行了调整和优化,为喷油器的结构设计和材料选用提供理论指导,提高设计成功率,降低开发成本。     

回油背压对高压共轨喷油器喷油特性影响的研究

高压共轨喷油器是柴油机高压共轨电控系统中最重要的一个部件,其喷油特性(如喷油器量)的优劣将直接影响发动机的性能表现。喷油器的喷射特性不仅受到喷油器的结构参数的影响,同时在喷射过程中还受到外界工作环境的影响,比如喷油器喷射时发动机缸内的背压,以及喷油器工作时的回油通道中的背压。本文主要对某高压共轨喷油器进行台架试验测试,研究喷油器回油背压对喷油特性的影响,并分析产生影响的原因,为开发新型的燃油喷射系统提供试验数据。     

压电式喷油器结构参数对喷油特性影响的研究

为研究喷油器关键结构参数对喷油规律的具体影响,采用GT-Fuel软件对高压共轨压电式喷油器进行了建模和仿真计算,研究了喷孔数、喷孔直径、针阀锥角、压力室容积等结构参数对喷油率和针阀升程的影响。分析结果表明:增加喷孔数或减小喷孔直径可以提高喷油压力和针阀响应速度,优化喷油率;增大针阀锥角可以优化喷油特性,但会产生较大压力波动;较小的压力室容积可产生预喷射现象,提高燃油燃烧稳定性。该研究为喷油器结构设计和优化提供了参考依据,具有较高推广和实用价值。     

某车型发动机碳烟排放分析及解决措施

某车型发动机在试验过程中,出现多起碳烟排放超标问题.为解决此问题,通过对故障车辆进行数据检测、分析可能原因,最终锁定故障原因为喷油器喷油异常导致,以此对喷油器进行方案论证和试验验证,锁定碳烟异常原因,为后续类似排放问题以及风险规避提供有效解决方案,为喷油器喷油设计提供宝贵经验.     

直喷发动机失火故障分析与优化策略

失火会影响发动机的可靠性、动力性、经济性和排放性能,是发动机的常见故障,引起失火故障的原因也有很多,涉及到发动机各个子系统。本文分析了某汽油直喷发动机在试验过程中出现的失火故障,主要存在有两种不同的失效模式,一则为点火线圈与火花塞的匹配问题：火花塞电极磨损后间隙变大,点火线圈无法提供足够的点火电压;另一则为喷油器与喷油策略的匹配问题：喷油器阀针行程大,在原有的喷油间隔要求下,影响二次喷油;通过改进点火线圈的性能;控制喷油器的阀针行程,同时调整喷油间隔时间,解决了发动机失火故障。     

喷油器技术状况检测技术研究

随着喷油器使用时间的增加,其主要部位和零部件的技术状况会下降,影响喷油质量,进而影响发动机的性能。本文根据检测目标对当前的喷油器技术状况检测技术进行了分类,总结了传统检测方法,并列举了部分改进方法及检测效果。     

电控燃油系统位置检测和驱动装置的研究

本文分析了柴油机燃油系统电控原理,研制出适用于电控燃油系统的一种新型的位置检测和驱动装置,并对其原理,输出特性以及灵敏度进行了分析,实验结果表明该装置能满足燃油系统电控性能的要求。     

An investigation of the spray characteristics of diesel-DME blended fuel with variation of ambient pressure in a constant volume combustion chamber

We compared the spray characteristics of a typical fuel (100% diesel, DME) and diesel-DME blended fuel in a constant volume combustion chamber (CVCC). The typical fuel (100% diesel, DME) and diesel-DME blended fuel spray characteristics were investigated at various ambient pressures (pressurized nitrogen) and fuel injection pressures using a common rail fuel injection system when the fuel mixture ratio was varied. The fuel injection quantity and spray characteristics were measured including spray shape, penetration length, and spray angle.     

半差动环形角度传感器的研究

本文研制了适用于电控燃油系统的一种新型角度传感器,并对其结构、工作原理以及测量电路进行了分析。分析结果表明该传感器的特性能满足电控燃油系统性能的要求。     

An experimental study on the spray characteristics of a dual-orifice type swirl injector at low fuel temperatures

The objective of this study is to investigate the effects of fuel temperature on the spray characteristics of a dual-orifice type swirl injector used in a gas turbine. The major parameters affecting spray characteristics are fuel temperature and injection pressure entering into the injector. In this study, the spray characteristics of a dual-orifice type swirl injector are investigated by varying fuel temperature from — 30°C to 120°C and injection pressure from 0.29 to 0.69 MPa. Two kinds of fuel having different surface tension and viscosity are chosen as atomizing fluids. As a result, injection instability occurs in the low fuel temperature range due to icing phenomenon and fuel property change with a decrease of fuel temperature. As the injection pressure increases, the range of kinematic viscosity for stable atomization becomes wider. The properties controlling the SMD of spray is substantially different according to the fuel temperature range.     

An investigation on the spray characteristics of DME with variation of ambient pressure using the common rail fuel injection system

We investigated the DME spray characteristics about varied ambient pressure and fuel injection pressure using the common rail fuel injection system when the nozzle holes diameter is varied. The common rail fuel injection system and fuel cooling system were used since DME has compressibility and vaporization at atmospheric temperature. The fuel injection quantity and spray characteristics were measured. The spray was analyzed for spray shape, penetration length, and spray angle at the six nozzle holes. There are two types of injectors: 0.166 mm diameter and 0.250 mm diameter. The ambient pressure, which was based on gage pressure, was 0, 2.5, and 5 MPa. The fuel injection pressure was varied by 5 MPa from 35 to 70 MPa. By comparing with the common injector, using the converted injector it was shown that the DME injection quantity was increased 127% but it didn??t have the same low heating value. Both the common and converted injectors had symmetric spray shapes. In case of converted injector, there were asymmetrical spray shapes until 1.2 ms, but after 1.2 ms the spray shapes were symmetric. Also, the converted injector had shorter penetration length and wider spray angle than the common injector.     

An experimental study on spray and combustion characteristics based on fuel temperature of direct injection bio-ethanol-gasoline blending fuel

This study investigated the spray and combustion characteristics of a direct injection spark ignition type system based on the changes in the temperature of the blended fuel (with bio-ethanol and gasoline). The test was performed in a chamber with a constant volume. The diameter and width of the chamber were 86 mm and 39 mm, respectively. The bio-ethanol test fuel was blended at volume ratios of 0 %, 10 %, 20 % and 100 %. The temperature of the fuel was set as −7, 25 and 35 °C. The fuel injection pressure and ambient pressure were set as 4.5 and 0.5 MPa, respectively. The shape and characteristics of the spray were investigated through a spray experiment. The increase in the fuel temperature changed its density and viscosity; this in turn increased spray penetration and spray area and increased the bio-ethanol blending ratio. The combustion visualization and experimental analysis indicated that the decrease in the fuel temperature and the increase in the bio-ethanol blending ratio led to the high viscosity and low heating value. This resulted in an increase in the ignition delay and a decrease in the rate of heat release. It is necessary to adjust the spray strategy and ignition timing to adopt bio-ethanol blended fuel as an alternative fuel.

     

An experimental study on the evaporation of freely falling droplet under high temperature and high pressure gas stream

An experimental apparatuses and measuring system have been made to obtain characteristics connected with evaporation, ignition delay, combustion of a freely falling liquid fuel droplet in high temperature and high pressure gas stream. In this study some systematic experiments were performed to test the utility of the system. The newly devised apparatus was ensured reliability and utility from the tentative experimental results.     

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.     

Comparison of experimental and predicted atomization characteristics of high-pressure diesel spray under various fuel and ambient temperature

The aim of this study is to investigate the effects of the fuel temperature and the ambient gas temperature on the overall spray characteristics. Also, based on the experimental results, a numerical study is performed at more detailed and critical conditions in a high pressure diesel spray using a computational fluid dynamics (CFD) code (AVL, FIRE ver. 2008). Spray tip penetration and spray cone angle are experimentally measured from spray images obtained using a spray visualization system composed of a high speed camera and fuel supply system. To calculate and predict the high pressure diesel spray behavior and atomization characteristics, a hybrid breakup model combining KH (Kelvin-Helmholtz) and RT (Rayleigh-Taylor) breakup theories is used. It was found that an increase in fuel temperature induces a decrease in spray tip penetration due to a reduction in the spray momentum. The increase of the ambient gas temperature causes the increase of the spray tip penetration, and the reduction of the spray cone angle. In calculation, when the ambient gas temperature increases above the boiling point, the overall SMD shows the increasing trend. Above the boiling temperature, the diesel droplets rapidly evaporate immediately after the injection from calculation results. From results and discussions, the KH-RT hybrid breakup model well describes the effects of the fuel temperature and ambient gas temperature on the overall spray characteristics, although there is a partial difference between the experimental and the calculation results of the spray tip penetration by the secondary breakup model.     

喷射压力对生物柴油混合燃料喷雾特性的影响

基于KH-RT液滴破碎模型对定容燃烧弹内生物柴油-正丁醇混合燃料的喷雾贯穿距离、喷雾锥角、索特平均粒径、速度场以浓度场进行数值模拟,通过定容燃烧弹试验台架获取的生物柴油-正丁醇混合燃料的喷雾特性对数值模型进行验证,结果表明:随着喷射压力的增加,BD70N30混合燃料的喷雾贯穿距和喷雾锥角增加;索特平均粒径降低;雾束中心...