单缸EGR发动机压缩比优化及涡轮增压器匹配研究

在1台气道喷射单缸EGR发动机上,独立控制EGR缸喷油及点火,实现燃料改质,研究了不同压缩比对发动机性能的影响,此外还匹配了不同涡轮增压器,用于改善外特性扭矩。试验结果表明:单缸EGR能有效改善发动机的燃油经济性,NOx和CO排放性能均所改善,但THC排放恶化,动力性能下降;提高压缩比能有效提高发动机的热效率,降低燃油消耗,但过高压缩比使发动机爆震倾向严重,限制发动机外特性扭矩;通过匹配小涡轮增压器低速扭矩有所改善。     

催化燃烧应用于均质压燃发动机的几种计算模型

通过耦合DETCHEM软件包及CHEMKIN软件包中的SENKIN模块,对活塞顶及活塞冠周边涂有催化剂的HCCI发动机燃烧过程进行了数值计算,建立了多区模型。针对在处理缝隙区存在催化剂时出现的一些问题,提出了4种不同的计算模型,对比分析了这4种计算模型与基准模型在缸内温度、放热率和HC,NOx以及CO排放等方面的差别。     

基于Inventor的舞台板转动机构运动仿真与分析

采用Inventor软件建立舞台板转动机构的虚拟样机模型,用Inventor软件的插件Simulation模块进行运动仿真分析。分析结果对缩短产品的开发周期,提高设计质量有指导意义。所使用的仿真方法对舞台板转动机构设计具有重要的参考价值。     

一种料斗与压板联动的新型后装压缩式垃圾车

针对目前市场上所使用的后装压缩式垃圾车存在的结构缺陷,介绍了一种结构简单、易操控、改装成本低、整车轴荷分配合理、使用经济性好的新型后装压缩式垃圾车,并对该车的结构和工作原理进行了阐述。     

一种后装压缩式垃圾车倾倒装置

通过对多种后装压缩式垃圾车倾倒装置的研究,结合倾倒装置自身的安装位置和设计目的,总结出一套设计方法。即通过液压油缸驱动四杆机构运动,以合适的挂桶高度和倾倒角度,实现垃圾桶从地面提升,桶中垃圾倒入车内,再使垃圾桶放回地面的全过程。其关键点是确定合适的四杆尺寸和凸轮的形状。     

RCS土壤固化剂加固土的试验研究

利用RCS土壤固化剂对宁乡两种典型土质进行了固化试验研究,研究结果表明,掺人0．015％的RCS固化剂后,试件最大干密度变大,最佳含水率的变化不明显;CBR值和7d无侧限抗压强度增大;同时,掺加一定量的水泥可以明显提高RCS固化土的水稳定性和抗压强度,可取得良好的效果。试验结果表明这种固化剂具有较强的实用价值和应用前景。     

外部热EGR对基于优化动力技术的汽油HCCI燃烧的影响

考察了外部热EGR对基于优化动力技术的汽油HCCI发动机燃烧的影响。试验结果表明:外部热EGR可以推迟HCCI燃烧的着火时刻,减缓放热速率,但对于高辛烷值燃料的HCCI燃烧,它对更高EGR率的兼容能力不强,需要提高进气温度来提高燃烧的稳定性;随着EGR率的增加,燃烧持续期延长,缸内温度和压力峰值均减小,指示热效率也随着减小;NOx排放随着EGR率的增加在经过一个"拐点"后始终维持在一个较低的水平,而CO和HC的排放随着EGR率的增加显著增加,燃烧恶化。     

Application of a self-tuning fuzzy PI–PD controller in an active anti-roll bar system for a passenger car

A fuzzy proportional-integral-derivative (PID) controller has not been widely investigated for active anti-roll bar (AARB) application due to its unspecific mathematical analysis and the derivative kick problem. This paper briefly explains how the derivative kick problem arises due to the nature of the PID controller as well as the conventional fuzzy PID controller in association with an AARB. There are two types of controllers proposed in this paper: self-tuning fuzzy proportional-integral–proportional-derivative (STF PI–PD) and PI–PD-type fuzzy controller. Literature reveals that the PI–PD configuration can avoid the derivative kick, unlike the standard PID configuration used in fuzzy PID controllers. STF PI–PD is a new controller proposed and presented in this paper, while the PI–PD-type fuzzy controller was developed by other researchers for robotics and automation applications. Some modifications were made on these controllers in order to make them work with an AARB system. The performances of these controllers were evaluated through a series of handling tests using a full car model simulated in MATLAB Simulink. The simulation results were compared with the performance of a passive anti-roll bar and the conventional fuzzy PID controller in order to show improvements and practicality of the proposed controllers. Roll angle signal was used as input for all the controllers. It is found that the STF PI–PD controller is able to suppress the derivative kick problem but could not reduce the roll motion as much as the conventional fuzzy PID would. However, the PI–PD-type fuzzy controller outperforms the rest by improving ride and handling of a simulated passenger car significantly.     

Achieving anti-roll bar effect through air management in commercial vehicle pneumatic suspensions

ABSTRACT

This paper introduces the concept of managing air in commercial vehicle suspensions for reducing body roll. A conventional pneumatic suspension is re-designed to include higher-flow air hoses and dual levelling valves for improving the dynamic response of the suspension to the body roll, which commonly happens at relatively low frequencies. The improved air management allows air to get from the air tank to the airsprings quicker, and also changes the side-to-side suspension air pressure such that the suspension forces can more readily level the vehicle body, much in the same manner as an anti-roll bar (ARB). The results of a multi-domain simulation study in AMESim and TruckSim indicate that the proposed suspension configuration is capable of providing balanced airflow to the truck’s drive-axle suspensions, resulting in balanced suspension forces in response to single lane change and steady-state cornering steering maneuvers. The simulation results further indicate that a truck equipped with the reconfigured suspension experiences a uniform dynamic load sharing, smoother body motion (less roll angle), and improved handling and stability during steering maneuvers commonly occurring in commercial trucks during their intended use.     

醋酸钙镁代替食盐作为融雪剂对钢筋腐蚀性问题的研究

对醋酸钙镁代替食盐作为融雪剂的关键问题之一“融雪剂对钢筋的腐蚀性”进行了研究,通过实验对国内和国外在应用醋酸钙镁作为融雪剂方面普遍担心的两个问题进行了验证。结果表明醋酸钙镁代替食盐作为融雪剂可以大幅度降低对钢筋的腐蚀。