内燃机车真空制动系统的检测

通过对真空制动系统的简单介绍,基于真空制动系统的特性,得出在真空制动系统检测中,真空压力表起到重要的作用。     

Energy and wear optimisation of train longitudinal dynamics and of traction and braking systems

Traction and braking systems deeply affect longitudinal train dynamics, especially when an extensive blending phase among different pneumatic, electric and magnetic devices is required. The energy and wear optimisation of longitudinal vehicle dynamics has a crucial economic impact and involves several engineering problems such as wear of braking friction components, energy efficiency, thermal load on components, level of safety under degraded or adhesion conditions (often constrained by the current regulation in force on signalling or other safety-related subsystem). In fact, the application of energy storage systems can lead to an efficiency improvement of at least 10% while, as regards the wear reduction, the improvement due to distributed traction systems and to optimised traction devices can be quantified in about 50%. In this work, an innovative integrated procedure is proposed by the authors to optimise longitudinal train dynamics and traction and braking manoeuvres in terms of both energy and wear. The new approach has been applied to existing test cases and validated with experimental data provided by Breda and, for some components and their homologation process, the results of experimental activities derive from cooperation performed with relevant industrial partners such as Trenitalia and Italcertifer. In particular, simulation results are referred to the simulation tests performed on a high-speed train (Ansaldo Breda Emu V250) and on a tram (Ansaldo Breda Sirio Tram). The proposed approach is based on a modular simulation platform in which the sub-models corresponding to different subsystems can be easily customised, depending on the considered application, on the availability of technical data and on the homologation process of different components.     

制动条件下连挂救援动车组车钩垂向偏转行为

为了研究连挂救援动车组在制动条件下产生的冲击,建立了不同编组形式下的动车组动力学模型。考虑实际的车钩运动关系和缓冲器迟滞特性,建立了钩缓装置的动力学模型。制定了连挂救援动车组的运行安全阈值,分析了紧急制动时动车和钩缓系统的动力学响应,研究了直线工况下车钩的动态偏转行为与动车编组形式、制动减速度和车钩自由转角等参数对动车组运行安全性的影响。计算结果表明:A类动车组连挂救援B类动车组,直线上制动时连挂断面的压钩力和车钩点头角分别达到799.4kN和11.5°,钩尾框托梁垂向力和车端垂向相对位移分别达到136.2kN和126.2mm,明显超过允许限值,即80kN和95mm,车钩力垂向分量会造成车体点头和轮重减载现象,从而导致局部结构破坏和车间运动干涉。当制动档位降到7级或车钩自由点头角低至4°时,钩尾框前箱托梁垂向力低于限值,而车端垂向相对位移超过限值;当制动档位降到6级或车钩自由点头角低至2°时,可保证车端垂向相对位移低于允许值。     

汽车制动能量再生系统复合储能方式研究

对由铅酸电池与超级电容并联,并在铅酸电池与超级电容之间采用两象限DC/DC转换器控制的复合储能方式进行研究,建立其简化的等效电路模型,并从能量流的角度出发建立复合储能系统能量流模型,在Matlab/Simulink环境下对模型进行仿真计算,并在课题组搭建的汽车能量再生系统硬件在环仿真试验台上进行了试验,结果表明复合储能器能量回收率远高于单个储能器回收的能量值,并且复合储能系统的使用有利于制动能量回收与利用的优化管理。     

薄圆桶压电振子的弯曲振动分析

薄圆桶压电振子是薄金属圆桶底部粘合压电陶瓷圆片的振动元件.文章利用瑞利—里兹法,采用弹性边界约束条件,对薄圆桶压电振子的振动特性进行理论分析,推导得到压电振子振动频率方程,通过数值计算分析支撑结构对压电振子频率的影响,为该类传感器的研制提供设计依据.经分析计算,当压电振子中陶瓷圆片结构确定时,振子的谐振频率随支撑结构厚度的增加、半径的减小而增大.其中当金属底面厚度与振子总厚度之比在0.5～0.75之间时,振子谐振频率变化缓慢,当两者厚度比超过0.75后,谐振频率迅速增高;而当压电圆片与支撑结构半径比在0.4～0.9之间变化时,振子谐振频率随两者半径比的增大而增加,变化斜率也略有增大.     

High-speed trains subject to abrupt braking

The dynamic response of high-speed train subject to braking is investigated using the moving element method. Possible sliding of wheels over the rails is accounted for. The train is modelled as a 15-DOF system comprising of a car body, two bogies and four wheels interconnected by spring-damping units. The rail is modelled as a Euler–Bernoulli beam resting on a two-parameter elastic damped foundation. The interaction between the moving train and track-foundation is accounted for through the normal and tangential wheel–rail contact forces. The effects of braking torque, wheel–rail contact condition, initial train speed and severity of railhead roughness on the dynamic response of the high-speed train are investigated. For a given initial train speed and track irregularity, the study revealed that there is an optimal braking torque that would result in the smallest braking distance with no occurrence of wheel sliding, representing a good compromise between train instability and safety.     

Rollover detection and control on the non-driven axles of trucks based on pulsed braking excitation

The major challenges for rollover detection are the accurate modelling of vehicle dynamics and the real-time estimation of the varied parameters. To circumvent the dependence on vehicle parameters, a novel rollover detection method based on the pulsed braking excitation is proposed. With the lateral load transfer ratio (LTR), the relationship between rollover risks and non-driven wheel rotational dynamics is deduced, which is the basis to apply braking excitation on wheels. The lateral acceleration is adopted as the first criterion to activate the rollover detection. Once the pulsed braking is applied to the non-driven wheels, the braking pressure and wheel angular speeds are measured to estimate the LTR on the non-driven axle. In case of emergency, the differential braking-based anti-rollover is implemented. Experiments were conducted on a Hardware-in-Loop bench. The results show that, the pulsed braking can be activated timely, and the LTR on the non-driven axle is estimated accurately. With the anti-rollover control, the roll stability is improved considerably.     

Optimisation of active suspension control inputs for improved performance of active safety systems

A collocation-type control variable optimisation method is used to investigate the extent to which the fully active suspension (FAS) can be applied to improve the vehicle electronic stability control (ESC) performance and reduce the braking distance. First, the optimisation approach is applied to the scenario of vehicle stabilisation during the sine-with-dwell manoeuvre. The results are used to provide insights into different FAS control mechanisms for vehicle performance improvements related to responsiveness and yaw rate error reduction indices. The FAS control performance is compared to performances of the standard ESC system, optimal active brake system and combined FAS and ESC configuration. Second, the optimisation approach is employed to the task of FAS-based braking distance reduction for straight-line vehicle motion. Here, the scenarios of uniform and longitudinally or laterally non-uniform tyre–road friction coefficient are considered. The influences of limited anti-lock braking system (ABS) actuator bandwidth and limit-cycle ABS behaviour are also analysed. The optimisation results indicate that the FAS can provide competitive stabilisation performance and improved agility when compared to the ESC system, and that it can reduce the braking distance by up to 5% for distinctively non-uniform friction conditions.     

铁道车辆车轮和制动技术的发展趋势

介绍了欧洲对铁道车辆车轮和制动性能所进行的改进,探讨了美国货车ECP制动技术在欧洲运用的可能性。     

国外160 km/h快速货车制动系统

介绍了国外 160km /h快速货车制动系统的发展特点