城轨列车减速度反馈制动力闭环控制方法

针对城轨列车在目前理论减速度开环控制模式下,实际制动减速度精度较低的问题,提出一种基于参数估计的制动力闭环控制方法.将列车运行于坡道、弯道等路段产生的附加运行阻力和摩擦副摩擦系数变化等导致的实际制动力偏差等效为列车在制动过程中所受的总扰动,以列车减速度和制动缸压力等作为输入,通过梯度估计方式对该扰动进行求解.根据总扰动...     

Stability of Metal Matrix Composite Pads During High-Speed Braking

Metal matrix composites are now commonly used as braking pads for the train running over 250 km/h by virtue of a number of desirable properties. To develop a fundamental understanding of the stability of metallic composites at high-speed braking, four typical composite materials, with different Cu and Fe contents, were subjected to a series of high-speed emergency braking at a simulative running speed of 380 km/h and a braking inertia of 27 kg/m^?2 and a normal pressure of 1.27 MPa in this paper. The results showed that the sample with higher Cu content displayed a fade COF and deteriorated wear, but the one with higher Fe content could maintain a stable COF and low wear rate. The tribological behaviour is associated with the relative rate of generation and consumption of the tribo-oxide film. For the sample with higher Cu content, the generation rate of tribo-oxide film was less than the consumption rate, and the COF fading and wear deterioration with the increasing braking times were attributed to the reduction in resistance to deform or to shear the asperities, which was thought to be caused by the degradation of near-surface layer due to the removal of protective tribo-oxide film. In contrast, for the sample with higher Fe content, the generation rate was approximately equal to the consumption rate, and a well-established tribo-oxide film on the surface was responsible for the stable friction level and low wear rates.     

Design and Analysis of Electro-mechanical Hybrid Anti-lock Braking System for Hybrid Electric Vehicle Utilizing Motor Regenerative Braking

Braking on low adhesion-coefficient roads, hybrid electric vehicle's motor regenerative torque is switched off to safeguard the normal anti-lock braking system (ABS) function. When the ABS control is terminated, the motor regenerative braking is readmitted.Aiming at avoiding permanent cycles from hydraulic anti-lock braking to motor regenerative braking, a novel electro-mechanical hybrid anti-lock braking system using fuzzy logic is designed. Different from the traditional single control structure, this system has a two-layered hierarchical structure. The first layer is responsible for harmonious adjustment or interaction between regenerative system and anti-lock braking system. The second layer is responsible for braking torque distribution and adjustment. The closed-loop simulation model is built. Control strategy and method for coordination between regenerative and anti-lock braking are developed. Simulation braking on low adhesion-coefficient roads with fuzzy logic control and real vehicle braking field test are presented. The results from simulating analysis and experiment show braking performance of the vehicle is perfect, harmonious coordination between regenerative and anti-lock braking function, significant amount of braking energy can be recovered and the proposed control strategy and method are effective.     

汽车真空辅助制动系统的设计与研究

以汽车紧急制动工况为研究对象,设计和研制了一种汽车真空辅助制动系统,该系统主要包括机械执行机构、制动吸盘、真空系统、弹射收起系统、控制系统五个部分。对该系统进行了理论分析和实验研究,结果表明,该系统可显著提高汽车制动效能, 可有效缩短汽车紧急制动时的制动距离,从而有效降低交通事故的发生概率并降低交通事故的严重程度。     

渣罐列车制动计算分析

针对某集团公司排渣用渣罐列车的制动系统，经过理论计算分析，得出列车制动力、制动距离及列车质量之间的关系，为列车安全运行提供理论依据。     

Driving and braking control of PM synchronous motor based on low-resolution hall sensor for battery electric vehicle

Resolvers are normally employed for rotor positioning in motors for electric vehicles,but resolvers are expensive and vulnerable to vibrations.Hall sensors have the advantages of low cost and high reliability,but the positioning accuracy is low.Motors with Hall sensors are typically controlled by six-step commutation algorithm,which brings high torque ripple.This paper studies the high-performance driving and braking control of the in-wheel permanent magnetic synchronous motor(PMSM) based on low-resolution Hall sensors.Field oriented control(FOC) based on Hall-effect sensors is developed to reduce the torque ripple.The positioning accuracy of the Hall sensors is improved by interpolation between two consecutive Hall signals using the estimated motor speed.The position error from the misalignment of the Hall sensors is compensated by the precise calibration of Hall transition timing.The braking control algorithms based on six-step commutation and FOC are studied.Two variants of the six-step commutation braking control,namely,half-bridge commutation and full-bridge commutation,are discussed and compared,which shows that the full-bridge commutation could better explore the potential of the back electro-motive forces(EMF),thus can deliver higher efficiency and smaller current ripple.The FOC braking is analyzed with the phasor diagrams.At a given motor speed,the motor turns from the regenerative braking mode into the plug braking mode if the braking torque exceeds a certain limit,which is proportional to the motor speed.Tests in the dynamometer show that a smooth control could be realized by FOC driving control and the highest efficiency and the smallest current ripple could be achieved by FOC braking control,compared to six-step commutation braking control.Therefore,FOC braking is selected as the braking control algorithm for electric vehicles.The proposed research ensures a good motor control performance while maintaining low cost and high reliability.     

Regenerative braking control strategy in mild hybrid electric vehicles equipped with automatic manual transmission

The actual regenerative braking force of an integrated starter/generator (ISG), which is varied with desired braking deceleration and vehicle speed, is calculated based on an analysis of the required deceleration, maximum braking force of ISG, engine braking force and state of charge (SOC) of battery. Braking force distribution strategies are presented according to the actual regenerative braking force of ISG. To recover the vehicle’s kinetic energy maximally, braking shift rules for a mild hybrid electric vehicle (HEV) equipped with automatic manual transmission (AMT) are brought forward and effects of transmission ratios are considered. A test-bed is built up and regenerative braking tests are carried out. The results show that power recovered by the braking shift rules is more than that recovered by the normal braking control rules. __________ Translated from Chinese Journal of Mechanical Engineering, 2006, 42(10): 156–160 [译自: 机械工程学报]     

基于Agent的电液复合制动系统防抱死控制研究

针对纯电动汽车电液复合制动系统电机再生制动力与液压制动力动态响应特性的差异及其非线性特性问题,提出了一种基于Agent的电液复合制动防抱死控制方法。构建了由电机Agent、液压制动Agent和ABS Agent组成的复合制动系统,依据让步策略、竞争策略和协同策略对电机再生制动力和液压制动力协调分配。MATLAB/Simulink仿真结果表明：紧急制动状态下,各Agent间能有效协作,前轮始终先于后轮进入抱死趋势,复合制动系统可以准确识别路面附着系数变化并及时调整电机制动力与液压制动力,提高了制动稳定性与系统的自适应能力。     

一种附着系数实时可调的汽车制动模拟试验台 设计、分析与实验研究

为了实现车辆制动模拟试验中附着系数的准确模拟和实时可调,设计了一种汽车制动模拟试验台,通过控制磁粉离合器励磁电流,实时模拟不同路面附着系数;搭建了基于路面识别的单轮车辆制动系统仿真模型,进行了单一路面和跃变路面下的制动仿真;研制了车辆制动模拟实验系统,开展了单一路面下汽车制动模拟实验和跃变路面下附着系数跟踪控制实验。研究结果表明,在湿沥青路面上以120 km/h初速度制动时,相比于基于固定目标滑移率,基于路面识别的最佳滑移率下的制动距离缩短了3.1%,且在低附着路面下更为明显;单一路面下制动时车速和轮速的实验值与仿真值基本吻合;跃变路面下附着系数最大跟踪误差仅为6.2%,跟踪控制效果良好。     

摩擦副组合对摩擦磨损性能的影响

在1：1惯性力矩制动试验台上研究了两种不同石墨形态的铸铁制动盘与两种混杂纤维增强的酚醛基制动闸片配副时的摩擦磨损性能。结果表明，对于某一配方的制动闸片，使用灰口铸铁盘的摩擦副具有较高的摩擦系数，但制动盘表面温度较高，闸片磨损量较大；对于某一种制动盘，使用B配方制动闸片时，制动盘表面的温度较高，但闸片的磨损量较小；在所有四种组合中，B配方制动闸片与灰口铸铁盘配副的瞬时摩擦系数能够完全满足有关技术要求。     

盘式制动系统参数对制动颤振的影响分析

为了研究盘式制动系统参数对制动颤振的影响,建立了二自由度的动力学模型,利用Matlab进行数值仿真,分别研究了制动初速度、制动压力、阻尼和刚度等因素对制动系统动力学特性的影响。根据得到的位移曲线和相图可以看出:随着制动初速度的增大,系统黏滞阶段持续时间减少,并逐渐进入稳定运动状态;制动压力相对较小时,制动系统处于稳定状态,随着制动压力的增大,摩擦片和制动盘的振动幅值也随之增大,振动强度变大;在阻尼增大的过程中,摩擦片和制动盘均由起初的纯滑动运动状态进入稳定运动状态,且达到稳定运动状态的时间也逐渐缩短;摩擦片在相对较小的制动刚度下即可达到稳定状态,而制动盘则需要有较大的刚度才能达到稳定状态。     

液驱混合动力车辆的制动能量回收研究

建立了液驱混合动力车辆制动能量回收的数学模型,对制动能量回收过程中的能量损耗、能量回收和制动性能进行仿真计算和分析,并对制动初始压力和蓄能器容积等主要设计参数对制动能量回收效率以及车辆制动性能的影响进行了定量分析,为液驱混合动力车辆液压系统进一步的优化设计和控制打下了良好的基础．     

基于间隙热源法的车轮踏面制动摩擦温升研究

针对传统模拟车轮踏面制动摩擦热流边界的加载方式存在的不足,如均布热源法计算精度较低和移动热源法计算效率较低,提出基于间隙热流加载法的车轮踏面制动摩擦温升有限元计算方法。以重载列车紧急制动为研究对象,通过与以往的移动热源法和均布热源法进行对比,研究新方法的计算精度和计算效率。计算结果显示:在计算精度方面,新方法不仅可以达到移动热源法的计算精度,还能体现均布热源法无法模拟的因闸瓦和踏面的接触-脱离现象导致的车轮踏面温度时间历程曲线波动现象。在计算时间方面,新方法的计算效率与均布热源法的相当,但新方法的计算速度比移动热源法的快4.3倍。     

[轮轨磨耗及预测]列车紧急制动过程中踏面温度分布及磨耗预测

列车紧急制动过程中踏面温度急剧升高导致车轮踏面的摩擦磨损机理与稳态运行时有显著差异。为了准确预测列车紧急制动过程中踏面磨耗,同时考虑踏面制动过程中车轮踏面与钢轨及闸瓦接触,基于有限元软件ABAQUS建立了踏面制动过程热机械耦合有限元模型,综合考虑制动温升对车轮踏面力学性能、硬度及摩擦因数的影响,仿真得到了紧急制动过程中车轮踏面上温度分布、硬度分布以及接触应力分布,并利用轮轨动力学软件UM得到了紧急制动过程中轮轨接触斑形状以及轮轨蠕滑区相对滑移分布,在此基础上结合Archard磨耗模型对单次紧急制动结束后的踏面磨损深度进行了定量预测。结果表明：对于制动初速度为130 km/h、160 km/h两种工况,踏面最高温度分别达到了397.0 ℃和485.9 ℃,踏面最大累积磨损深度分别为5.90 μm和7.43 μm,与踏面制动实验对比发现,预测结果与实验结果磨损位置及形貌分布趋势一致。     

多轴车制动的动力学模型及制动性能分析

通过分析经典车辆制动动力学模型应用于多轴车制动计算时存在的问题,提出了引进悬架变形协调方程的通用化多轴车直线制动动力学模型,推导了多轴车直线制动时地面法向反作用力的通用计算公式,并提出了一种便于计算机语言实现的直接计算多轴车抱死顺序的算法。基于该算法,推导了地面制动力、制动减速度和制动距离的通用计算公式。     

On the role of sliding load and heat input conditions in friction stir processing on tribology of aluminium alloy–alumina surface composites

ABSTRACT

Aluminium (AA5083)-alumina surface composites are prepared by friction stir processing in two conditions of heat input. The low heat (LH) input conditions is achieved at a rotational speed of 710?rpm and a traverse speed of 100?mm/min, and high heat (HH) input conditions are achieved at a rotational speed of 1400?rpm and a traverse speed of 40?mm/min. The tribological characteristics of aluminium alloy, friction stir processed (FSPed) alloy and FSPed surface composites against steel ball are studied at 5, 10 and 20?N load. While no significant influence is found on frictional behaviour, wear resistance of FSPed composites is superior to FSPed alloys. FSPed composites fabricated at HH input conditions exhibited improved wear resistance as compared to LH input condition. Adhesion and delamination are dominant wear mechanisms at 20?N. Debris particles are reduced in size and hydroxidated in sliding of surface composites.     

基于SVM的电梯制动器静态制动力矩估算方法研究

针对电梯制动器静态制动力矩估算问题,对电梯制动器的动态制动性能与静态制动性能分别进行了研究,利用电梯制动器试验台测试制动器的制动性能,根据实验测试结果提出了一种基于支持向量机的电梯制动器静态制动力矩估算方法,将利用制动器动态制动性能实验得到的制动初始速度与制动过程的平均制动力矩作为估算算法训练数据的输入值,将相同制动器对应的静态制动力矩作为估算算法训练数据的输出值,经过支持向量机算法训练得到估算模型,采用网格搜索法进一步优化估算模型。最后,通过制动实验进一步采集制动性能数据作为验证数据。实验结果显示,电梯制动器的动态制动性能与制动初始速度有关。交叉验证的结果表明,基于SVM的电梯制动器静态制动力矩估算方法能够便捷准确地根据电梯制动器的动态数据估算出静态制动性能。     

Investigating the Lubricity and Electrical Insulation Caused by Sanding in Dry Wheel–Rail Contacts

The adhesion (or available friction) in the wheel–rail contact is the most important parameter for the braking and traction operation of rail vehicles. Since the beginning of railway transportation, sanding from the locomotive has been a common practice to enhance the wheel–rail adhesion. In recent years, sanding from electrical multiple units (EMUs) and sand-based friction modifiers (FMs) have been adopted in some railway networks to overcome low adhesion incidents caused by leaf contamination in autumn. Although sanding has been proven to improve the adhesion under most of the typical contamination conditions, laboratory and field investigations have shown that sand may act as a solid lubricant in dry wheel–rail contacts. Nevertheless, the influence of the current sanding parameters on the solid lubrication effect has not been entirely investigated. Depending on the resulting adhesion coefficient, the traction and braking operations of rail vehicles could be affected. Furthermore, the influence of those parameters on the electrical insulation is also of special importance because it may affect the train detection. This article presents a laboratory investigation of the influence of three sanding parameters (i.e., feed rate, particle size, and slip) on the adhesion and electrical insulation in dry wheel–rail contacts. The tests have been carried out with a twin-disk roller rig in rolling-sliding motion under closely controlled conditions. Three different slips representative of the actual traction and braking operations have been considered. Sands of four different sizes and up to five feed rates have been used. The results show that using smaller particle sizes and higher feed rates promotes the lubrication and causes more electrical insulation in the wheel–rail contact. Furthermore, the increase in slip is found to reduce the lubrication, leading to a higher adhesion coefficient.     

基于混合仿真技术车辆ABS控制系统快速开发研究

叙述了利用先进计算机技术和仿真软件,进行车辆ABS电子控制系统快速开发的过程。首先建立车辆模型和ABS控制模型,然后进行纯仿真计算,实时仿真计算以及混合仿真计算,从而达到对车辆ABS控制逻辑快速开发的目的。最后把研制的ABS控制器应用于桑塔纳2000型试验样车进行实车道路试验,取得较好的效果。该开发系统具有较好的扩展性,也可用于其他车辆电子控制系统快速开发,从而为在较少的前期投入和短时期内开发出合格的汽车电子产品以迅速占领市场提供了新思路。     

An investigation into friction behaviour of dispersion-strengthened copper under severe railway braking conditions

A dispersion-strengthened copper (DSC) has been studied as an alternative material for railway brake discs, to be used in severe railway braking applications. Compared to standard steel, the DSC shows a more homogeneous thermal field at the friction surface. This also applies in depth, both avoiding hot spots. This thermal behaviour implies a lower wear and a very interesting friction coefficient evolution without any “anti-fade” phenomenon.