Full Power Hydraulic Brake System Based on Double Pipelines for Heavy Vehicles

The hydraulic caliper disc brake system with air-over-oil is widely adopted at present for heavy vehicles,which makes use of air pressure system propelling the hydraulic pressure system acting on friction plates divided and combined for braking.There are some disadvantages such as pneumatic components failure,dust polluted and produce lots of heat in hydraulic caliper disc brake system.Moreover,considering the demands of the high speed,heavy weight,heavy load and fast brake of heavy vehicles,the full power hydraulic brake system based on double pipelines for heavy vehicles is designed and analyzed in this paper.The scheme of the full power hydraulic brake system,in which the triloculare cylinder is controlled by dual brake valve,is adopted in the brake system.The full power hydraulic brake system can accomplish steering brake,parking brake and emergent brake for heavy vehicles.Furthermore,electronic control system that is responsible for coordinating the work of hydraulic decelerator and hydraulic brake system is developed for different speed brakes.Based on the analysis of the influence of composed unit and connecting pipeline on braking performance,the nonlinear mathematic model is established for the full power hydraulic brake system.The braking completion time and braking pressure in braking performance of the double-pipeline steering brake and parking brake are discussed by means of simulation experiments based on Matlab/Simulink,and the simulation results prove that the braking performance of steering brake and parking brake meets the designing requirement of the full power hydraulic brake system.Moreover,the test-bed experiments of the brake system for heavy vehicles are carried out.The experimental data prove that the braking performance achieves the goal of the design,and that the full power hydraulic brake system based on double pipelines can effectively enhance braking performance,ensure braking reliability and security for heavy vehicles.

Dynamic Simulation and Valve Structure Optimization of an Electro-Hydraulic Clutch Shift Control System in an Automatic Transmission

The electro-hydraulic clutch control system controls the transferred torque of gear-shifting clutches in clutch-to-clutch transmissions. A nonlinear dynamic model of an electro-hydraulic clutch shift control system is presented. The mechanical and fluid subsystems of all valves are investigated, including their interactions. Model validation of the electro-hydraulic valve system is performed by comparing the simulated and measured pressure curves. The dynamic characteristics of the electro-hydraulic clutch shift control system with different supply pressures and different fluid temperatures are simulated and evaluated. It is found that pipes which are often ignored between the electro-hydraulic valve system and the clutch piston,have strong influence on clutch piston chamber pressures. In order to satisfy the required time and reduce the fluctuation of the clutch piston chamber pressures,the orifices' diameters and valve structure are optimized.

STUDY ON THE CONTROL SYSTEM OF HYDRAULIC MOMENT-ADJUSTED BRAKE FOR DOWNWARD BELT CONVEYOR

Having analyzed the drawbacks on the design of control system of hydraulic moment-adjusted brake system, the author presents a closed loop control system in the process of start and braking of the conveyer. On the basis of the concept of the critical time and the critical ac-celeration and its deductions, the working mode of the conveyer can be identified and controlled in feedback, furthermore, thus realize the process of soft start. ln the deceleration process, the author points out the problems that exist in the present control system and sets forward the control process that acted by the combined function of brake moment of motor and the drag torque of hy-draulic brake at the beginning of deceleration, it will further improved reliability of conveyor sys-tem.

基于ADAMS/Hydraulics模块的液压离合器液压系统仿真

简要介绍ADAMS及其Hydraulics模块的特点,利用ADAMS/Hydraulics模块建立液压离合器模型,同时对液压离合器的液压系统进行仿真研究。结果表明,液压离合器在液压缸的驱动下,可以完成工作过程中的主要动作,工作安全可靠,液压缸运行平稳,无较大冲击,为液压离合器液压系统的进一步研究及优化提供参考。

Parameters Matching and Control Method of Hydraulic Hybrid Vehicles with Secondary Regulation Technology

Hydraulic hybrid vehicles （HHV） with secondary regulation technology has the potential of improving fuel economy by operating the engine in the optimum efficiency range and making use of regenerative braking. Hydrostatic transmission technology has the advantage of higher power density and the ability to accept the high rates and high frequencies of charging and discharging, both of which are not favorable for batteries, but the lower energy density requires special power matching design and control strategy to coordinate all the powertrain components in an optimal manner. A multi-objective optimization method is proposed to distinguish the components size values of HHV by considering the requirements of driving cycles and technology aspects. The regenerative braking strategy and energy control strategy based on the optimized HHV is proposed to recovery the braking energy and distribute the regenerated braking energy. Simulation results show that by taking the optimized configuration of HHV, adopting the regenerative braking strategy and energy control strategy are helpful to improve the system efficiency and fuel economy of HHV under urban driving cycles.

Operation control strategy of series-parallel hydraulic hybrid vehicle

A series-parallel hydraulic hybrid system applied to public buses is put torwaro, ano parameters of key components are analyzed and determined. Energy management strategy based on logic thresh- old is designed which is aimed at efficient operation of the overall system considering the operational characteristic of the components and taking the curves of engine, hydraulic pump/motor and hydrau- lic pump as the main design basis; regenerative control strategy which makes regenerative brake sys- tem and frictional brake system work harmoniously is designed to raise recovery rate of regenerative brake energy. System dynamic modeling and simulation results show that the energy control strategy designed here is able to adapt system to changes of working condition and switch the operating mode reasonably. The regenerative braking control strategy is effective in raising the utilization of energy and improving fuel economy.

Research on Electro Hydraulic Proportional Control for Heavy Vehicle Blend Braking System

A blend braking system of heavy vehicle was proposed.The main control part of the system is the electro hydraulic proportional servo valve.A nonlinear model of brake cylinder controlled by the valve was deduced through the analysis of its control property and system feature.The transfer function of the system was also proposed,and the hydraulic inherent frequency and the PID closed-loop system feature were calculated.The simulated result is consistent with those tested in the bench and on the site with 50 t heavy vehicle.The experimental result shows that the control method has quick response and high precision.

A New Type of Automotive Braking Actuator for Decentralized Electro-hydraulic Braking System

This paper presents a new type of automotive braking actuator for a kind of brake-by-wire system called decentralized electro-hydraulic braking system( DEHB) to replace the traditional automobile braking system. The actuator of this system is driven by an electrical motor instead of the conventional vacuum booster to make the brake pressure be linearity controlled quickly. Therefore,the system has the advantages of quick response speed,good control performance and simple structure. Firstly,an overview of the actuator and the whole DEHB system is shown. Secondly,the possibility of this new kind of actuator working for the system is ensured based on some braking theories. Thirdly,the appropriate dynamic simulations are done to get some results to show the relations of different parameters and the effect of braking. Eventually,the proper parameters are determined to build a test bench which shows that DEHB system can achieve the maximum pressure of 13 MPa within 100 ms after parametric optimization,and meanwhile,the actuator is able to reduce pressure quickly after maintaining high pressure. All of the bench test results can meet with the design requirements and real demand of vehicle and this actuator may improve vehicle braking effect in the future. Besides,this actuator can be widely applied to the regenerative braking system because of its linear braking performance.

Position Control Optimization of Aerodynamic Brake Device for High-speed Trains

The aerodynamic braking is a clean and non-adhesion braking, and can be used to provide extra braking force during high-speed emergency braking. The research of aerodynamic braking has attracted more and more attentions in recent years. However, most researchers in this field focus on aerodynamic effects and seldom on issues of position control of the aerodynamic braking board. The purpose of this paper is to explore position control optimization of the braking board in an aerodynamic braking prototype. The mathematical models of the hydraulic drive unit in the aerodynamic braking system are analyzed in detail, and the simulation models are established. Three control functions--constant, linear, and quadratic--are explored. Two kinds of criteria, including the position steady-state error and the acceleration of the piston rod, are used to evaluate system performance. Simulation results show that the position steady state-error is reduced from around 12-2 mm by applying a linear instead of a constant function, while the acceleration is reduced from 25,71-3.70 m/s2 with a quadratic control function. Use of the quadratic control function is shown to improve system performance. Experimental results obtained by measuring the position response of the piston rod on a test-bench also suggest a reduced position error and smooth movement of the piston rod. This implies that the acceleration is smaller when using the quadratic function, thus verifying the effectiveness of control schemes to improve to system performance. This paper proposes an effective and easily implemented control scheme that improves the position response of hydraulic cylinders during position control.

基于转鼓转速传感的中低速新能源汽车联合制动系统控制方法

中低速新能源汽车是常见的交通工具,但是其制动控制存在响应时间长、控制效果差的问题,设计一种基于转鼓转速传感的中低速新能源汽车联合制动系统控制方法。首先,构建基于转鼓转速传感的中低速新能源汽车动力学方程,采集传感信息,然后,考虑开环控制容易导致控制系统的稳定性和鲁棒性差的问题,基于转鼓转速传感的联合制动系统传递函数推导出开环、闭环双传递函数,最后,根据系统传递函数,设计PID控制器的参数,通过PID控制器输出电-液联合制动控制信号,实现汽车联合制动系统控制。实验结果表明:所提方法的速度-位移曲线与现实速度-位移曲线基本一致,加速误差在-0.5 m/s2~0.5 m/s2范围内,平均制动控制响应时间为0.075 s,具有良好的制动控制能力。

多轴分布式电驱动车辆电液复合制动控制研究

针对多轴分布式电机驱动车辆电液复合制动中易出现的车辆制动抖动问题,提出了一种建压阶段电机制动力修正策略和一种基于前馈-反馈的协调控制策略,分别在建压阶段和其他阶段通过协调复合制动力来解决制动抖动的问题。针对防抱死控制系统与电机制动系统共同作用时的制动矛盾,提出了一种基于PID控制的ABS控制策略,主要通过改变电机制动力来解决制动矛盾的问题。通过TruckSim、Matlab/Simulink及AMESim联合仿真验证,制动冲击度在建压阶段下降了20.66%,在电机退出阶段下降了92.59%,驾驶感觉得到明显改善。而ABS控制策略也可在保证理想滑移率的同时完成制动能量回收;结合整车制动试验,表明协调控制策略在保证制动效果良好的同时实现了制动能量回收,效果显著。

电动汽车电控液压制动系统CarSim/Simulink联合仿真研究

针对某款国产电动汽车的电控液压制动系统,文章基于滑移率的比例-积分-微分(PID)控制提出了防抱死制动系统(ABS)模型,以改善车辆制动性能,提高在对开路面上的制动有效性和安全性。首先,使用Simulink软件建立液压电控制动系统的动力学模型;然后,基于滑移率设计PID控制器,并通过1/4车辆模型验证其有效性;最后,利用S函数将ABS控制器的Simulink模型输入CarSim平台中,开展CarSim/Simulink双平台联合控制仿真。结果表明,基于滑移率的PID控制的ABS对比无ABS的车辆,制动性能更加优越,在对开路面上制动稳定性更加明显。

集成式电液制动系统自适应压力控制

针对集成式电液制动系统(integrated electro-hydraulic brake system,IEHB)存在的复杂液压非线性特性和时变摩擦干扰,提出一种自适应压力控制策略。外环压力控制器引入液压特性的动态线性化模型并基于滑模观测器对模型参数实时辨识实现对非线性液压特性的自适应。内环伺服控制器采用基于压力的连续摩擦补偿和反步动态面控制应对传动机构摩擦阻碍。硬件在环实验结果表明,与现有的先进级联压力控制相比,设计的压力控制策略在多种工况下均表现出更高的控制精度和鲁棒性,并显著提升了IEHB在不同液压回路结构下的压力控制效果。

寒冷地区电液制动器的油液黏度-时间模型及制动特性研究

针对寒冷地区电液制动器制动力和制动力矩不足等导致水闸制动系统发生溜车问题,基于液压油Vogel黏温模型以及当地温度变化数据,构建了油液黏度随时间变化的黏度-时间模型,并基于该模型对电液制动器制动过程中油液流动特性进行了研究,然后对电液制动器制动性能进行了定量分析。结果表明:在制动过程中,电液制动器液压油压力主要分布在活塞底腔,且随着黏度增大而逐渐增大,当油液黏度为662.4 Pa·s时,压力达到1.455×10^(-3)MPa,电液制动器液压油在叶轮中心轴部位会出现涡流循环,其循环强度随着油液黏度的增加而逐渐增加;在给定工况下,该电液制动器的最小制动力为1098 N,最小制动力矩为274 N·m。而这一制动力矩已低于该电液制动器工作力矩范围,此时可以通过更换该月份黏度更小的液压油或增设预加热系统等措施来提高其制动力和制动力矩,从而实现正常制动。

面向混合动力汽车液压再生能量控制策略研究

针对混合动力汽车制动能量回收控制,提出了一种基于模糊Q学习的液压再生制动系统能量回收效率优化算法。建立了基于并联液压混合动力系统的汽车动力学模型,通过模糊Q学习法对汽车再生制动控制策略进行了优化。在此基础上建立了试验平台,验证液压再生制动仿真模型的准确性。与基于专家经验的模糊控制策略、动态规划算法相比,结果表明,经模糊Q学习算法优化的汽车节能率分别提高了9.62%和8.91%。

多目标拓扑优化算法在液压制动器传热优化中的应用

为有效提升液压制动器的传热性能,基于多目标优化算法对风冷盘的厚度、风槽高度、肋片倾角和肋片数量等设计变量进行拓扑优化,实现制动盘温度峰值和质量的同步降低。采用PDE方程建立风冷盘传热模型,以负热流为边界条件,求解出恒压匀速制动工况下的二维瞬态温度场。基于ANSYS Workbech建立风冷盘的三维参数化传热模型,利用台架试验法验证温度场仿真结果。采用中心组合设计法得出设计变量与优化目标的离散样本,通过多元二次回归模型构建代理模型并进行误差校核。构建优化数学模型,将质量优化目标转换为边界条件,通过序列二次规划算法得出不同质量区间的解集。结合min-max标准化和加权归一方法,得出无量纲的指标测评值,实现优化目标的性价比评价。优化结果表明,风冷盘质量降低8.3%,温度峰值降低3.7%,传热效率明显提升,经济效益和社会效益显著。

电液混合动力系统关键技术及能量管理研究综述

现有混合动力驱动技术以油电、油液混合动力为主,旨在提高传统燃油车辆的能量利用率、降低油耗和排放.基于液压技术的大功率密度及能量再生优势,电液混合动力系统可在全速工况范围内实现能量高效利用,提高纯电驱系统的功率密度,有效改善电动车辆续驶里程及蓄电池循环使用寿命.本文对电液混合动力系统构型、能量回收技术、能量释放模式及控制策略等相关研究成果的进展、现状及发展趋势进行综述,分析了利用电液混合动力构型与先进能量管理策略提升纯电动车辆动力性能与能量利用率的可行性技术方案与应用前景.根据已有研究成果,装备电液混合动力系统后车辆最大可降低约40%的能量消耗,在能量高效利用方面具有显著优势.对于电液混合动力系统而言,液压能再生、耦合与释放等与行驶场景及电机工况点密切相关,研究重点应解决动力耦合、再生制动与能量管理等关键技术,从而提升动力系统的综合性能特别是功率密度与节能特性.

某型船用大功率液控离合器传动系统联合仿真研究

进行了有关船用大功率液压驱动齿式离合器运动学及接触动力学的Adams和AMESim联合仿真流程研究,并进行了联合仿真交互操作界面开发,在给定参数下,能够输出可视化的计算结果。仿真分析结果表明,齿式离合器轴向接合过程的动态特性与冲击载荷受到主动端扭转刚度与轮齿端面结构的影响;减压阀最大开口压力为2.5 MPa,该压力下的最大推力为1.884×10^(5) N;在内外圈发生碰撞时,油压会急速上升,如果减压阀的流量不足,则进油油路会泄漏。经过多次联合仿真发现,进口压力在0.008~0.01 MPa就能实现在4 s左右完成离合器的接合脱开过程。

集成式电子液压线控制动系统建模与仿真

为了解决线控制动系统模型复杂、仿真困难等问题,文章针对一款常见的集成式电子液压线控制动(integrated electronic hydraulic brake,I-EHB)系统,推导其数学模型并进行仿真分析;在MATLAB/Simulink中搭建线控制动系统的仿真模型,设计比例积分微分(proportion integration differentiation,PID)制动控制器,实现对集成式电子液压线控制动系统的压力控制。仿真结果表明:该线控制动系统在PID控制器作用下实际输出压力值能够较好地跟随理想压力值,可以提供较好的制动效果。该文的研究对于线控底盘的开发具有积极推动作用。

弹射与阻拦一体式电磁弹射装置的电磁特性分析

针对线性弹射装置占地面积大、结构复杂和质量大的固有缺点,提出一种单轴一体式钢索拖动新型电磁弹射和阻拦装置。装置由永磁储能电机、电涡流离合器、电涡流制动器和绕线轮等组成。介绍了装置的结构和工作原理。基于安培环路定理建立电涡流离合器和电涡流制动器的电磁理论模型。通过与三维有限元计算结果对比,分析电涡流离合器和电涡流制动器的电磁特性。通过制作的电涡流制动器的小型试验样机验证电磁理论模型的正确性和有效性,最终进行动力学分析。研究结果表明,该装置可以使30000 kg的飞机在2.1 s内从0 m/s加速到70 m/s,并能够使72 m/s的飞机在2.6 s停下,满足设计指标的要求。