Pneumatic train brake simulation method

The design of new pneumatic brakes for rail vehicles or improvements of existing ones can be made better or more efficient by the use of a simulation method. This paper gives a general presentation of the author’s modelling methods used for solving problems relating to railway pneumatic brakes. The brake models in this paper (slightly different from those of other authors) take into account air-wave phenomena including air viscosity, the influence of the brake pipe branches, heat transfer in the brake pipes and reservoirs, air flows in the brake valves and the dynamics of moving mechanical parts. For various simulation purposes, separate partial models with different levels of accuracy were created. Various verifications and identifications of the models were performed with the use of train brake testing facilities, including both in-house and other test stands. A variety of examples of simulation results are presented here.     

一种制动试验台制动力检测系统的标定方法

FZD-9010B制动试验台为滚筒反力式制动试验台,是目前用于车辆制动性能检测的常规设备。基于虚拟仪器的FZD-9010B制动试验台检测系统可以实现制动力的动态、实时检测并可得制动过程的制动力曲线。针对于制动力检测系统的标定问题,笔者阐述一种有效的标定方法,通过设计一个杠杆机构,并借助标准砝码来实现的。该方法具有结构简单、有效、易于操作和实施的特点。     

Structural optimization of a circumferential friction disk brake with consideration of thermoelastic instability

This research suggests a new disk brake design using circumferential friction on the disk of a front-wheel-drive passenger car. The paper compares mechanical performance between the conventional and suggested disk brakes under dynamic braking conditions. Thermoelastic instability is considered in simulation of the test condition. An optimization technique using a metamodel is introduced to minimize the weight of the suggested disk brake. To achieve this goal, the response defined in the optimization formulation is expressed in a mathematically explicit form with respect to the design variables by using a kriging surrogate model, resulting in a simple optimization problem. Then, the simulated annealing algorithm is utilized to find the global optimum. The design results obtained by the kriging method are compared with those obtained from ANSYS analysis.     

Estimation of the adhesion force for a disc brake in a skid control condition

The performance of brakes has become important due to increased train speeds. The brake system of a train must possess a large brake force to stop the train safely within a limited stopping distance. However, an excessive brake force deteriorates the ride comfort and causes the train to skid. Therefore, it is necessary to control the brake force within the adhesion force limit. This paper presents an analytical method to estimate the relationship between the brake and adhesion forces of a disc brake system. This method has been applied to the actual disc braking control system of the Korea High-Speed Train (HSR350x), and the adhesion force is estimated in an actual skid condition.     

汽车气压盘式制动器的结构特点与性能分析

介绍了几种国内外重型汽车气压盘式制动器的结构及其特点,从左右轮制动力差异,制动器的效能因数与摩擦系数的关系及迟滞量等方面对盘式制动器与鼓式制动器进行性能对比分析,说明盘式制动器在制动效能、制动效能的稳定性以及制动时汽车的方向稳定性上比鼓式制动器具有明显的优势,理论和试验表明盘式制动器与ABS、ASR、EBS等系统匹配时可简化系统结构、优化系统性能,并对重型汽车装用盘式制动器带来的制动系统的相关问题进行了探讨.     

具有迟滞模拟记忆功能的奥迪盘式制动器可变线性模型

本文以奥迪１００盘式制动器为研究对象，建立了一种可模拟制动压力－力矩响应迟清点特性的可变线性模型，首先，介绍在ＪＦ－１３２型汽车制动器试验台上进行防抱制动器模拟试验的方法，其次，在获得大量试验数据的基础上，运用曲线拟合和优化技术，建立制动压力－力矩关系的线性模型，心滞模型为线笥模型，最后，在相同制动压力输入的前提下，把模型的理论计算民试验结果进行对比分析了模型的有效性和精确性。     

New procedure to estimate the brake warping in a roller tester

Vehicle systems such as the steering, brakes and suspension greatly influence vehicle safety. Therefore, these systems must be inspected to guarantee that they are functioning correctly and to certify that the vehicle is functioning at a satisfactory safety level. In disc brakes, warping is one of the principal reasons for vibrations and noise, and it contributes to diminished brake efficiency. Currently, the International Motor Vehicle Inspection Committee (CITA) demands disc brake warping inspections occur during periodic motor vehicle inspections (PMVIs); however, the procedure to carry out this inspection is not well defined. In this investigation, the warping phenomenon has been analyzed, and a new inspection procedure is proposed.     

Model-based analysis of the mechanical subsystem of an air brake system

Most commercial vehicles such as buses and trucks use an air brake system, often equipped with an S-cam drum brake, to reduce their speed and/or to stop. With a drum brake system, the clearance between the brake shoe/pad and the brake drum may increase because of various reasons such as wearing of the brake shoe and/or brake drum and drum expansion caused by high heat generation during the braking process. Hence, to ensure proper functioning of the brake system, it is essential that the clearance between the brake shoe and the brake drum is monitored. In this paper, we present a mathematical model for the mechanical subsystem of the air brake system that can be used to monitor this clearance. This mathematical model correlates the push rod stroke transients and the brake chamber pressure transients. A kinematic analysis and a dynamic analysis of the mechanical subsystem of the air brake system were performed, and the results are corroborated with experimental data.     

Direct tire force generation algorithm based on non-iterative nonlinear inverse tire model

The function of vehicle dynamics control system is adjusting the yaw moment, the longitudinal force and lateral force of a vehicle body through several chassis systems, such as brakes, steering and suspension. Individual systems such as ESC, AFS and 4WD can be used to achieve desired performance by controlling actuator variables. However, integrated chassis control systems that have multiple objectives may not simply achieve the desired performance by controlling the actuators directly. Usually those systems determine the required tire forces in an upper level controller and a lower level controller regulates the tire forces through the actuators. The tire force is controlled in a recursive way based on vehicle state measurement, which may not be sufficient for fast response. For immediate force tracking, we introduce a direct tire force generation method that uses a nonlinear inverse tire model, a pseudo-inverse model of vehicle dynamics and the relationship between longitudinal force and brake pressure.     

Measurement of the disc-pad friction coefficient for mechanical brakes using direct and indirect methods

It is necessary to guarantee the proper brake force to stop a train safely in a limited distance and o adjust its speed. Currently, most trains are run by electrical power and have a combined electrical and mechanical (friction) braking system. The mechanical brake force is determined by many parameters, such as the friction coefficient of the brake disc and pad, the pressure in the brake cylinder, the brake cylinder’s cross sectional area and the brake linkage ratio. In general, the friction coefficient data of the brake disc and pad have been taken through a dynamo-test in a laboratory, but these data might not be well matched with real data under operating conditions because of the difference in data acquisition conditions. The present study examined two methodologies that can measure the friction coefficient of the brake pad and disc based on a train’s real operating conditions. The first method was the direct method, which measured the brake force and clamping force applied on the mechanical brake by using strain gauges installed on the brake to calculate the friction coefficient. The second was an indirect method that obtained the friction coefficient by using the weight of the train and the equivalent brake force. Those variables were calculated from the longitudinal dynamic characteristics, such as resistance to motion, gradient resistance and curved resistance. These two methodologies were used to obtain the disc-pad friction coefficient for the mechanical brakes of a Korean high-speed train (HSR350x).     

汽车制动器制动效能因数计算及结果分析

对47种型号的汽车液压制动系统制动器的制动效能因数进行了计算，得到了当摩擦因数为0.35时各种结构型式制动器制动效能因数的平均值及其分布范围。绘制了国产各种结构型式制动器典型的制动效能因数随摩擦衬片摩擦因数变化的特性曲线。对同一制动器采用两种不同的制动效能因数计算方法所得计算结果进行了对比及验证。根据制动效能因数曲线图，提出了制动器系列化设置时减少制动器尺寸规格的设想。     

车用轮胎压力与温度监测系统的研究

汽车胎压监视系统主要用于在汽车行驶时实时地对轮胎气压、温度进行自动监测,对轮胎漏气、气压异常高温进行报警。制动系统的性能与驾乘人员安全密切相关,因此制动气压的精准性是一个非常重要的问题。     

Verification of pneumatic railway brake models

The article presents a survey of diverse methods for validation of pneumatic train brake modelling. Various experimental measurements of railway pneumatic brakes were made chiefly on a test stand at Poznań University of Technology; other test stands and some results have been taken from the literature. The measurements, some of them unconventional, were performed on separate pneumatic elements, brake devices, the brake pipe and fragments thereof. Mechanical devices were also included. The experimental measurement results were used for the verification of numerical models and for the determination of parameters. The latter was partially performed using an optimisation method.     

Brake pad taper wear on brake moan noise

Automotive brake systems today have many factors that can contribute to brake noise. Modern approaches to reduce the propensity of brake noise mostly target high frequency brake squeal. A more difficult constituent of brake noise to address is low frequency moan, which is typically caused when the brake system excites a suspension member with a constrained natural frequency in the range of excitation. Although most modern CAE techniques utilized to diagnose and solve brake noise issues focus on new brake pad condition, this paper will show the benefit of understanding a common wear mechanism “Taper Wear,?and attempt to correlate its effects on brake moan. In order to study this phenomenon, a finite element model of a disc brake is established, and a complex eigenvalue analysis (CEA) of the brake system is performed. The propensity of brake moan noise is evaluated on basis of damping ratio of a dynamic brake system model. By using the finite element model, effects of the brake pad taper wear on brake moan noise is studied. The results show that the brake pad taper wear is a significant factor for generating the instability causing the brake moan noise. The study is performed at various levels of brake pad taper wear. When the brake pad taper wear is more than 0.5 mm, the value of negative damping ratio rapidly increases, and the propensity of brake moan noise is greatly magnified. In this study, the simulation result correlated well with the test result, which provides the theory and guidance for brake moan noise control.     

汽车轮胎侧偏特性影响因素的试验研究

应用轮胎静力学特性试验机，研究了低速条件下3种不同胎面花纹轮胎在干燥路面上的侧偏特性，主要分析了胎面花纹、轮胎负荷和轮胎气压等因素对轮胎侧偏特性的影响。结果表明：轮胎的Fy-α关系曲线形状与胎面花纹形式、轮胎负荷和胎压等均无关。而Mz-α关系曲线变化趋势与胎面花纹无关，却与轮胎负荷和气压有关；在相同试验条件下，顺向花纹轮胎具有更优异的附着性能和侧偏特性。     

Cooperative regenerative braking control for front-wheel-drive hybrid electric vehicle based on adaptive regenerative brake torque optimization using under-steer index

In this study, cooperative regenerative braking control of front-wheel-drive hybrid electric vehicle is proposed to recover optimal braking energy while guaranteeing the vehicle lateral stability. In front-wheel-drive hybrid electric vehicle, excessive regenerative braking for recuperation of the maximum braking energy can cause under-steer problem. This is due to the fact that the resultant lateral force on front tire saturates and starts to decrease. Therefore, cost function with constraints is newly defined to determine optimum distribution of brake torques including the regenerative brake torque for improving the braking energy recovery as well as the vehicle lateral stability. This cost function includes trade-off relation of two objectives. The physical meaning of first objective of cost function is to maximize the regenerative brake torque for improving the fuel economy and that of second objective is to increase the mechanical-friction brake torques at rear wheels rather than regenerative brake torque at front wheels for preventing front tire saturation. And weighting factor in cost function is also proposed as a function of under-steer index representing current state of the vehicle lateral motion in order to generalize the constrained optimization problem including both normal and severe cornering situation. For example, as the vehicle approaches its handling limits, adaptation of weighting factor is possible to prioritize front tire saturation over increasing the recuperation of braking energy for driver safety and vehicle lateral stability. Finally, computer simulation of closed loop driver-vehicle system based on Carsim? performed to verify the effectiveness of adaptation method in proposed controller and the vehicle performance of the proposed controller in comparison with the conventional controller for only considering the vehicle lateral stability. Simulation results indicate that the proposed controller improved the performance of braking energy recovery as well as guaranteed the vehicle lateral stability similar to the conventional controller.     

鼓式制动器摩擦副压强不均匀性分析与评价

定义了鼓式制动器摩擦片压强的两种不均匀度指数，推导了现有的不同机构型式的鼓式制动器的摩擦副压强不均匀度指数的计算公式，并分析了其变化特性。以这两种压强不均匀度指数作为新的评价指标，对各种型式的鼓式制动器进行了评价，揭示了一些型式的鼓式制动器所固有的缺点。提出了改进传统鼓式制动器的技术方向和途径。     

车辆持续制动时制动器热衰退现象研究

制动系统热衰退是引发交通事故的一个重要原因。如何降低汽车持续制动时制动器的热衰退以保证车辆的行驶安全性是摆在人们面前的一个急需解决的问题。针对这个问题,在这里就车辆持续制动时,对制动特征、产生热衰退现象的机理及降低制动系统热衰退的措施等方而问题进行了深入探讨研究。     

Development of a valve and optimization of a tube for self-inflating tire

Worldwide, the tire market requires safe and eco-friendly tires. In this study, a self-inflating tire (SIT) was studied and manufactured. Self-inflating tire refers to a technique for maintaining appropriate tire pressure. An internal regulator senses when tire inflation pressure has dropped below the set air pressure. The tire boosts air through the valve when rolling and compressed air enters into the tire. This procedure keeps the tire air pressure at an appropriate level and increases tire safety. In this study, a regulator was used as a negative-pressure system. A check valve was selected the minute flow check valve depending on the shape of the configured system. In addition, the material of the tube was developed with excellent physical properties and resistances (elastic rebound, working temperature, etc.) owing to its complete compression and restoration. A tube performance tester was developed and a computer aided engineering (CAE) model was modeled for comparison with the test results. Using the tester and model, it was possible to optimize the shape of the tube and regulator. Finally, the reliability of the study was verified through the prototype test. The developed equipment and systems can be used for the manufacture of high-performance and safe tires.     

35000kN机械压力机摩擦离合器与制动器的改进

针对第一汽车制造厂用于冲压生产的35000kN机械压力机原多盘摩擦离合器与制动器存在的问题,改进设计成单盘浮动镶块式的结构。并对有关问题进行了探讨。为大型机械压力机离合器与制动器的设计与改进提供了必要的参考数据,积累了实践经验。