均质压燃式发动机系统的改造及燃烧分析

对实验室原有的依维柯索菲姆柴油发动机进行燃油喷射系统和进排气系统的改造,使其实现均质压燃燃烧方式(HCCI)燃烧方式。同时加装数据和信号采集装置,以基础燃料进行燃烧,利用缸压采集和燃烧分析模块进行数据采集和分析。实验证明,通过对发动机原有燃油喷射系统和进排气系统的改造,完全能够实现HCCI燃烧方式,在过量空气系数λ为2.85左右时,发动机NO_x和碳烟的排放能同时降低。可以考虑改进排气系统和燃油喷射系统,将λ控制在理想值附近。     

均质压燃研究用模拟试验装置的研制

均质压燃(HCCI)过程在当前已经成为发动机燃烧的研究热点.不同燃料均质压燃性能差异很大,相关试验需要多台结构参数不同的试验用发动机,而在不同的发动机上因受多种因素的影响出现不同的燃烧特性,形成不同的对比性能.因此,采用燃烧边界条件可调的发动机模拟燃烧试验装置十分必要.设计的模拟试验装置不仅具备良好的边界条件可控性,而且具备适应多种燃料的试验功能.可以按照试验者的要求实现均质压燃过程的试验研究.论述了该试验装置的组成、工作原理及技术性能.     

基于数值模拟的柴油-天然气RCCI发动机不同预喷时刻下燃烧与排放特性研究

随着计算机技术的不断发展,数值模拟方法变得更加成熟,并成为现今内燃机研究的主要手段。文章运用CONVERGE软件,采用数值模拟方法,对柴油-天然气双燃料反应活性控制压燃发动机燃烧与排放性能进行研究。根据研究机型参数,进行三维几何模型的构建,优化仿真模型并实施数值计算模拟,建立了满足实际要求的发动机燃烧模型。采用数值模拟方法,得出二次喷射下不同预喷时刻缸内主要参数变化曲线及相关云图,找出最有利的预喷时刻段,对研究其他因素对双燃料发动机燃烧与排放特性的影响具有重要的指导意义和参考价值。     

基于模糊神经网络的车辆发动机建模和控制

本章针对车辆发动机是一个高度非线性、不确定的复杂系统,其模型难以建立的特点研究了基于模糊神经网络的发动机辨识技术。同时基于辨识模型和神经网络设计了发动机单变量鲁棒自适应控制系统。     

浅谈汽车发动机可变气门正时技术的发展及运用

普通自然吸气四冲程发动机工作时,气门的开启和关闭时刻并非恰好是活塞处于上、下止点的时刻,而是利用气流的气流动量惯性,气门适当提前点开启,延迟点关闭.此类发动机配气相位是固定不可改变的.为了使发动机充气量足、排气彻底,能够适应行驶过程中发动机不同的工况.通过适时改变配气相位,延长、缩短进、排气的时间,以达到进气充足排气干净的要求,提高发动机转矩和功率.     

压剪机的PLC控制

本文设计的压剪机PLC控制系统工作可靠,控制精度高,操作安全省力,具有计数和分拣功能。     

基于模糊神经网络的汽油机瞬态工况空燃比控制系统的研究

针对汽油机瞬态工况空燃比控制精度偏差的问题,结合模糊控制系统容错性、鲁棒性以及神经网络学习强的特点,提出了应用模糊神经网络控制瞬态工况空燃比的方法,进行了神经网络和模糊控制算法的分析,设计了基于模糊神经网络的空燃比控制器.通过应用MATLAB/Simulink平台仿真,验证了基于模糊神经网络的汽油机瞬态工况空燃控制系统的可行性.研究结果表明,模糊神经网络控制对瞬态工况空燃比的控制调节时间快,超调量小,具有一定的应用价值.     

基于PLC控制的多功能双向自动压装机设计

多功能双向自动压装机是根据用户需求专门研制的,用于压装汽车催化器的载体和汽车消声器的内组件的一种装置。该装置是由机械结构、气动控制、电气控制等部分组成的,采用三菱PLC、视觉传感器、气动元件、伺服驱动系统来实现不同产品可以在同一台设备上压装的要求,同时解决了载体或内组件在压入筒体中位置控制精度不高的问题,还具有实时监控功能,遇到不合格品能够自动识别报警。实践证明,该方案技术含量高、效果好,促进了汽车催化器载体和消音器内组件压装技术与工艺优化改进,取得了良好的社会效益和经济效益。     

共轨式柴油发动机的轨压PID控制仿真

在高压共轨系统中,对共轨压力的控制是提高内燃机性能的关键,针对被控对象的特点,建立了被控对象的仿真模型。采用PID控制算法实现了对共轨压力的闭环控制,利用MATLAB／SIMULINK对系统进行了仿真,为实现神经网络模糊PID控制算法在轨压控制中的应用打下了良好的基础。     

Experimental Study on Dimethyl Ether Combustion Process in Homogeneous Charge Compression Ignition Mode

Experimental study on homogeneous charge compression ignition (HCCI) combustion process was carried out on a single-cylinder direct injection diesel engine fueled with dimethyl ether(DME). The influence of inert gas CO2 on the ignition and combustion process was investigated. The research results indicate that because of the high cetanc number of DME, the stable HCCI operating range is quite narrow while the engine has a high compression ratio. The HCCI operating range can be largely extended when the inert gas is inducted into the charging air. HCCI combustion of DME presents remarkable characteristic of two-stage combustion process. As the concentration of inert gas increases, the ignition timing of the first combustion stage delays,the peak heat release rate decreases, and the combustion duration extends. Inducting inert gas into charging air cannot make the combustion and heat release of DME occur at a perfect crank angle position. Therefore, to obtain HCCI operation for the fuel with high cetane number,other methods such as reducing engine compression ratio should be adopted. Emission results show that under HCCI operation, a nearly zero NOx emission can be obtained with no smoke emissions. But the HC and CO emissions are high, and beth rise with the increase of the concentration of inert gases.     

Effects of Exhaust Gas Recirculation on the Homogeneous Charge Combustion Process of n-Heptane at Different Load Conditions

Effects of exhaust gas recirculation （ EGR） on homogeneous charge combustion of n-heptane was studied through simulation and experiment. Experiments were carried out in a single cylinder, four-stroke, air cooled engine and a single cylinder, two-stroke, water cooled engine. In the four-stroke engine, experiments of the effects of EGR were examined using heated N2 addition as a surrogate for external EGR and modifying engine to increase internal EGR. The ignition timing was sensitive to EGR due to thermal and chemical effects. EGR or extra air is a key factor in eliminating knock during mid-load conditions. For higher load operation the only way to avoid knock is to control reaction timing through the use of spark ignition. Experimental and modeling results from the twostroke engine show that auto-ignition can be avoided by increasing the engine speed. The twostroke engine experiments indicate that high levels of internal EGR can enable spark ignition at lean conditions. At higher load conditions, increasing the engine speed is an effective method to control transition from homogeneous charge compression ignition （ HCCI） operation to non-HCCI operation and successful spark ignition of a highly dilute mixture can avoid serious knock.     

A Fuzzy Homogeneous Combustion Control System

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Negative Valve Overlap Mode of HCCI Operation Using Gasoline and Diesel Blended Fuels

The negative valve overlap (NVO) strategy of HCCI operation was experimentally investigated on a gasoline HCCI engine operated with variable valve timing in association with the addition of diesel fuel. The experimental results show that, by using gasoline and diesel blended fuels, the required NVO interval for suitable HCCI combustion under a given engine speed and a moderate compression ratio condition could be reduced, and the HCCI combustion region was extended remarkably without substantial increase in NOx emissions under a given inlet and exhaust valve timing due to the improvement of charge ignitability. In addition, the possible scale of NVO was extended. A substantial increase in the lean limit of excess air ratio and the upper limit of load range can be achieved because of higher volumetric efficiency, resulting from the decrease in the required NVO and the presence of less residual gases in cylinder.     

Negative Valve Overlap Mode and Diesel of HCCI Operation Using Gasoline Blended Fuels

The negative valve overlap (NVO) strategy of HCCI operation was experimentally investigated on a gasoline HCCI engine operated with variable valve timing in association with the addition of diesel fuel. The experimental results show that, by using gasoline and diesel blended fuels, the required NVO interval for suitable HCCI combustion under a given engine speed and a moderate compression ratio condition could be reduced, and the HCCI combustion region was extended remarkably without substantial increase in NO, , emissions under a given inlet and exhaust valve timing due to the improvement of charge ignitability. In addition, the possible scale of NVO was extended. A substantial increase in the lean limit of excess air ratio and the upper limit of load range can be achieved because of higher volumetric efficiency, resulting from the decrease in the required NVO and the presence of less residual gases in cylinder.     

基于PLC控制的多段变频调速在矿井提升机中的应用

鉴于煤矿提升机在矿井安全中的重要地位,详细介绍了基于PLC控制的变频调速系统。该系统利用三菱变频器矢量控制性能优良的特点,通过三菱变频器的多段速控制实现了对提升机的无极调速。该系统已成功运用于某矿提升机电控系统中。     

一种不确定性机器人的变结构控制

考虑机器人的不确定项,首先利用反馈控制技术,把基于拉格朗日方程的多关节机器人动力学模型转化成一线性状态方程.然后基于此状态方程,运用变结构控制思想,并结合李雅普诺夫函数设计出一种新的机器人鲁棒控制器,这种控制器能够保证机器人机械臂的跟踪误差渐近收敛到零点.无论是理论推导还是实验仿真都说明了所设计的控制器有着很好的鲁棒性和有效性.     

流量控制变频调速系统在实验教学中的应用

流量变频调速控制系统变频器采用森兰SB60,根据输入给定值和反馈的实际值,即流量传感器信号转换获得的反馈电压信号,利用PID控制自动调节,改变频率输出值来调节所控制的三相异步电机转速,继而来调节水箱流量,实现流量控制的目的.     

基于网络控制与组态技术的过程控制实验室改造

在介绍"THJ-3型高级过程控制系统实验装置"组成的基础上,完成了基于C/S网络控制的1拖4的实验设备的改造,组建了系统的组态环境,并在组态环境下学生能够通过网络对过程控制装置在实验室的教师服务器上进行采集和控制,系统调试运行效果良好。通过网络技术对实验室的改造可以大大提高实验室的利用率,解决了实验室设备较少的问题,同时可以让学生能更好地了解学习现代网络控制和组态技术的优点。     

基于虚拟仪器的湿增压实验台测控系统研究

本文以湿增压动力装置实验台为物理模型,为进行相关实验完成了速度、流量、扭矩等重要参数的测量,并以NI6221硬件为基础,基于虚拟仪器平台LabVIEW研制了实验台的测试软件.新设计的测试系统是基于虚拟仪器平台的模块化系统,使得研究人员的大部分精力集中于所要实现的功能上,而不是以往繁琐的算法和重复的编程上,参数易于修改,缩短了系统开发的周期,能满足实验需求.