进气压力传感器检测和波形分析

进气歧管绝对压力传感器用于D型汽油喷射系统。它在汽油喷射系统中所起的作用和空气流量传感器相似。进气歧管绝对压力传感器根据发动机的负荷状态测出进气歧管内绝对压力的变化,并转换成电压信号,与转速信号一起输送到电控单元,作为确定喷油器基本喷油量的依据。在当今发动机电子控制系统中,应用较为广泛的有半导体压敏电阻式、真空膜盒传动式两种。     

卡特330C型挖掘机的C-9发动机排障两例

一台卡特330C型挖掘机,配装C-9 型电控发动机,该发动机的工作原理如附图所示。C-9型发动机的燃油喷射系统采用液压驱动电控单体喷射技术(HEUI)来控制喷油器的工作。发动机的工作系统可分为3个部分:电控系统、低压燃油供给系统和液压控制系统,电控系统是由电子控制模块(简称ECM)、各种传感器和执行器共同组成。电控系统由ECM监测各种传感器的输入信号, 并根据发动机的负荷及转速来控制喷油器的工作,以达到最佳的喷油正时、喷射持续时间和喷射压力,从而实现精     

现代汽车发动机电子控制系统及其传感器

现代车用发动机电控单元（ECU）又称为电子控制器或电子控制组件，是发动机控制系统的核心部件。电控单元主要由输入回路、单片微型计算机（单片机）和输出回路三部分组成。发动机电控单元的主要功用是接收各种传感器和控制开关输入的发动机工况信号，根据电控单元内部预先编制的控制程序和存储的试验数据，通过数学计算和逻辑判断确定适应发动机工况的喷油时间和点火提前角等参数，并将这些参数转换为电信号控制各种执行元件完成执行动作，从而使发动机保持最佳运行状态。     

电控发动机ECU故障检测仪设计

设计了一种电控发动机ECU检测系统.对离线的ECU输入模拟工作信号,激励其工作,测量ECU的喷油、点火脉宽等输出信号,通过与正常值比较来判断ECU电路板上存在故障的模块.系统实现了ECU各种工作参数的离线分析和显示.能够准确判断ECU故障部位.实验结果表明:该系统准确、可靠,提高了ECU的测试及维修效率.     

浅谈丰田卡罗拉曲轴位置传感器的工作原理及检测方法

曲轴位置传感器能检测上止点信号、曲轴转角信号和发动机转速信号,是电控单元计算点火时刻与喷油时刻的最主要依据之一。以丰田卡罗拉轿车曲轴位置传感器为例,分析了电磁式曲轴位置传感器的工作原理及检测方法,为诊断电磁式曲轴位置传感器的故障提供了一套全面、系统的检测方法。     

东风悦达起亚K5进气歧管绝对压力传感器的检测

电控发动机采用进气歧管绝对压力传感器来检测进气量的称为D型喷射系统，一般安装于节气门与发动机进气门之间。是根据发动机转速和负荷的大小检测出歧管内绝对压力的变化，间接的检测出进气量， PCM依据此信号电压的大小，控制基本喷油量的大小。     

柴油机电子控制系统(二)

这类系统的电控柱塞式喷油总成如图2a所示,喷油量和转速控制机构如图2b所示。它在传统喷油泵的机械调速器壳体内安装了线性电磁铁以取代机械调速器,在喷油泵凸轮轴的自由端安装了磁电式转速传感器(见图2a),用于检测发动机的转速;并在每个喷油分泵上增设一个可以移动的控制滑套(见图2c),用于调节喷油泵的喷油定时。电控单元根据加速踏板位置、发动机转速、涡轮增压器增压压力、冷却液温度、     

3412E型发动机动力不足的故障排除

我矿D10R型推土机配装3412E型发动机,燃油系统采用常规燃油系统与液压驱动和电子控制技术相结合,使燃油系统的工作更加稳定、耐用,并且不需要调整。其电控喷油器具有较高的灵活性,能调整发动机到最理想的工作性能,可根据发动机的转速控制喷油压力,通过多组传感器向电控器(简称ECM)输送信号来确定发动机的工作情况,通过这些输入信号控制燃油系统工作,从而大大降低了工作成本和环境污染。一台机器在运行了5000h后,作业时突然出现发动机动力不足,转速明显下降,无法进行作业,而在空载时发动机转速正常。检查了空气滤芯和燃油油     

汽车发动机电控燃油喷射系统

汽油机电控喷油系统是国外汽车工业70年代出现的一项高科技产品,该系统用传感器采集发动机工况参数,输入电脑(控制单元)来控制最佳喷油量和最佳点火时刻,使发动机的空燃比和点火提前角得到最优化控制,从而大大减少排气污染,降低油耗,提高功率和行驶性能。目前发达国家90％的轿车都采用了此项技术。     

电控直列泵─管─阀─嘴柴油喷射系统的机液特性研究

电控直列泵─管─阀─嘴（PPVI）柴油喷射系统是一种新型的电磁阀溢流控制式直列泵喷油系统,通过分析该系统内部的压力波动过程,确定电磁控制阀在高压油路中的连接方式和最佳位置,揭示该系统的喷油量、喷油定时、喷油压力及喷油速率等方面的喷射特性,通过系统结构设计、硬件调整和软件标定解决多缸机系统的油量均匀性问题,进行电控柴油机的台架试验,表明喷射特性的可控性及其对整机综合性能的改善效果。     

浅析电控燃油喷射系统的典型故障诊断

目前,电控燃油喷射系统（简称EFI）已在国内外轿车上广泛应用。但是在排除电控燃油喷射系统故障时,发现尽管故障现象不同,原因各异,但颇具典型性的当属氧传感器、冷却液温度传感器和节气门位置传感器的故障。它们不仅有故障率高的特点,而且对发动机工况的影响也较大。为此,笔者拟结合多年的车辆装备维修实践,以及到基层部队调研培训实际情况,就以上几种电控燃油喷射系统典型故障谈一下个人见解,仅供参考。     

凌志LS-400轿车发动机电控燃油喷射系统的故障模拟与实验分析

本文针对凌志LS-400轿车发动机电控汽油喷射系统的主要执行器和传感器,怠速控制阀、水温传感器、爆震传感器、氧传感器进行了故障模拟,并用示波器对各种故障产生后ECU的控制信号进行检测,将检测结果与理论分析进行对比。     

电喷汽油机冷起动性能研究

针对影响电喷汽油机冷起动性能的系统进行研究,包括起动系统、点火系统和电喷系统。在实车上对这些系统进行方案对比试验,分析其对电喷汽油机冷起动的具体影响。试验证明,对起动系统、点火系统和电喷系统进行优化可以有效地提高冷起动性能,并得到各个系统的最佳匹配点。     

Comparisons of predicted and measured results on performance and emission of engine effected by intake air dilution and supercharging

An experimental study was conducted on a single cylinder direct injection diesel engine to investigate the effects of diluting intake air, with different gases and increasing intake pressure on combustion process and exhaust emissions. The intake O₂ concentration is changed from 15% to 21% by diluting intake air with different gases (CO₂, Ar, N₂), and the intake pressure is changed from one to two bar by a screw compressor. A modified program for calculating heat release rate, is used to study the characteristics of combustion and exhaust emissions in detail. The main results show that the addition of either CO₂ or Ar to the intake air increases the ignition delay. The variations of ignition delay with CO₂ are much larger than those of ignition delay with Ar for the same O₂ concentration. The emission of NOx decreases with the decrease of O₂ concentration and the smoke level is lower with the addition of the CO₂ than with that of Ar. As the intake pressure is increased, the ignition delay is shortened. Furthermore the high intake air pressure enhances the air-fuel mixing and diffusion combustion, and reduces the premixed combustion, so that NOx emission is decreased without increasing smoke emissions. The addition of CO₂ at high intake pressure, drastically reduces NOx emissions and smoke emission simultaneously at a high load condition, and the addition of CO₂ reduces NOx emissions without affecting the smoke emissions substantially at a low load condition. A zero-dimensional combustion simulation program incorporated with the present heat release correlation and ignition delay correlation is used to predict ignition delay, cylinder pressure and engine power. The results show that the correlations are likely to be adequate for the engine operating under diluted intake air and various intake pressure.     

A study on in-cylinder flow field of a 125cc motorcycle engine at low engine speeds

The in-cylinder flow characteristics of a four-stroke, four-valve, pent-roof small engine of motorcycle at engine speeds from 2000 rpm to 4000 rpm were studied using computational fluid dynamics (CFD). The aim of this study was to investigate the in-cylinder flow characteristics of small engines, including tumble, swirl, turbulent kinetic energy (TKE), angular momentum, in-cylinder air mass, turbulent velocity, turbulent length scale, and air flow pattern (in both intake and compression strokes) under motoring conditions. The engine geometry was created using SolidWorks, then was exported and analyzed using CONVERGE, a commercial CFD method. Grid independence analysis was carried out for this small engine and the turbulence model was observed using the renormalized group (RNG) k-ɛ model. The pressure boundary conditions were used to define the fluid pressure at the intake and exhaust of the port. The results showed that the increase in the engine speed caused the swirl flow in the small engine to be irregularly shaped. The swirl flow had a tendency to be stable and almost constant in the beginning of the compression stroke and increased at the end of compression stroke. However, the increase of in engine speed had no significant effect on the increase in tumble ratio, especially during the intake stroke. There was an increase in tumble ratio due to the increase in engine speed at the end of compression stroke, but only a marginal increase. The increase in engine speed had no significant effect on the increase in angular momentum, TKE, or turbulent velocity from the early intake stroke until the middle of the intake stroke. However, the angular momentum increased due to the increase in engine speed from the middle of the intake stroke to the end of compression stroke, and the angular momentum achieved the biggest increase when the engine speed rose from 3000 to 4000 rpm by 10 % at the end of the intake stroke. The increase in engine speed caused an increase of TKE and turbulent velocity from the middle of intake stroke until the end of compression stroke. Moreover, the biggest increase of TKE and turbulent velocity occurred when the engine speed rose from 3000 to 4000 rpm at the middle of intake stroke around 50 % and 25 %, respectively. Turbulent length scales appeared to be insensitive to increasing engine speed, especially in the intake stroke until 490 °CA. From that point, the value of the turbulent length scale increased as engine speed increased. The biggest increase in the turbulent length scales occurred when the intake valve was almost closed (around 20 %) and the engine speed was within two specific ranges (2000 to 3000 rpm and 3000 to 4000 rpm). Regarding the effect of engine speed, there were no significant effects upon the accumulated air mass in the small engine. The increase in engine speed caused an increase of turbulence in the combustion chamber during the late stages of the compression stroke. The increase in turbulence enhanced the mixing of air and fuel and made the mixture more homogeneous. Moreover, the increase in turbulence directly increased the flame propagation speed. Further research is recommended using a new design with several types of intake ports as well as combinations of different intake ports and some type of piston face, so that changes in air flow characteristics in small engines can be analyzed. Finally, this study is expected to help decrease the number of experiments necessary to obtain optimized systems in small engines.

     

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。     

某缸内直喷发动机进气歧管CFD模拟分析

进气歧管控制着发动机各缸的进气,尤其对于多缸发动机,进气控制对发动机各循环变动的影响非常大。对于四缸以下发动机的进气歧管采用稳态CFD分析完全满足优化设计要求,但对于四缸以上发动机需要采用瞬态CFD分析方法更为合适。进气歧管是发动机最关键进气系统部件之一,其核心功能是为发动机各缸提供充足均匀的混合气,是影响发动机动力性和经济性的关键因素;除此之外,电喷系统主要传感器和执行器均安装在进气歧管上,导致进气歧管结构复杂和高成本。计算机模拟可以降低开发成本,文中用三维CFD软件对某缸内直喷发动机进气歧管进行了稳态流动分析,通过CFD分析基本可以确定进气歧管结构要求,指导实际产品设计。     

Multi-stage turbocharger system analysis method for high altitude UAV engine

A multi-stage turbocharger system analysis method has been presented for a hydrogen fueled internal combustion engine targeted for High altitude long endurance UAV (HALE UAV), of which cruising altitude is 60000 ft. To utilize an internal combustion engine as a propulsion system of a HALE UAV, proper inlet pressure boost system such as a series of turbochargers should be ready, which makes engine performance less sensitive to flight altitude. In this study, to boost rarefied intake air pressure up to 1.7 bar to avoid early ignition of hydrogen and to produce required power from engine, we used a boost system which consists of three-staged turbocharger accompanied by intercooler to reduce compressed air temperature. To analyze multi-stage turbocharger performance at the cruising altitude, we established an explicit one-dimensional analysis method by matching required power between compressors and turbines. Then adequate turbochargers were searched for from commercially available models based on performance analysis results. One-dimensional analysis was also applied from sea level to the cruising altitude to decide turbocharger operating lines were located within each turbocharger operating ranges.

     

滑阀式压缩空气发动机实验研究

为优化气动发动机设计,提高气动发动机的工作性能,在一台由四冲程汽油机改装的二冲程气动发动机上进行了详细的台架试验。提出一个评价气动发动机性能的新指标——气动发动机平均有效压力和缸内平均压力的比值。采用钢、铝和尼龙三种材料制作相同尺寸的配气滑块进行试验,结果表明配气滑块的质量,对气动发动机动力性有影响。对进气持续角为128 °、143 °和156 °的尼龙材料配气滑块进行试验,试验结果表明增大进气持续角可以提高压缩空气的膨胀效率。在三种不同压缩比的状况下进行了气动发动机试验。试验证明在传统内燃机的基础上改装气动发动机时,增大发动机压缩比,会降低压缩空气的膨胀效率。     

An investigation of the effect of changes in engine operating conditions on ignition in an hcci engine

The dependence of the ignition timing in an HCCI engine on intake temperature and pressure, equivalence ratio, and fuel species is investigated with a zero-dimensional model combined with a detailed chemical kinetics. The accuracy of the model is evaluated by comparing measured and computed results in a propane-fueled HCCI engine. It is shown that the peak pressure values are reproduced within 10% and ignition timing within 5° CA. The heat loss through the walls is found to affect significantly on the ignition timing for different inlet conditions. It is also shown that for the propane-fueled engine, the tolerance in intake temperatures is 20–25K and the tolerance in intake pressure is about 1 bar for stable operation without misfire or too early ignition. Comparison of propane and heptane fuels indicates that the tendency to misfire when heptane is employed as the fuel is less than that when propane is employed with the same wall temperature conditions. However, the heptane-fueled engine may have a Lower compression ratio to avoid too early ignition and hence lower efficiency. For the selected set of engine parameters, stable operations might be achieved for the heptane-fueled engine with twice as much tolerance in intake temperatures as for the propane-fueled engine.