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.

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.

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.

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.

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.

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。

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%。

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.

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。

基于AMESim汽车制动液压系统特性建模分析

制动液压系统是整车液压系统的关键部件,直接影响新车安全。根据车辆制动系统需求,对行车和停车两种制动液压系统的原理进行分析,在此基础上设计确定制动系统中制动器、制动泵、蓄能器、系统压力等主要结构单元的关键参数;基于AMEsim搭建制动液压系统的分析模型,对液压系统中蓄能器充液过程进行分析,研究充液阀溢流值与蓄能器充液压力之间的关系;对系统工作性能进行分析。采用液压测试系统对某实际车辆制动液压系统的工作过程进行测试,以验证前述分析的准确性。结果可知:充液阀中溢流阀的开启压力直接决定充液阀的功能是否能够实现,需综合考虑系统的最高充压和充液阀的充液速率;不同压力结果表明,所研究的制动系统溢流阀开启值最佳值为16.5MPa;实测结果为16.1MPa,与仿真分析结果误差为2.5%,同时变化规律也保持一致,表明前述分析的准确性,为同类设计提供参考。

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。

重载车辆再生缓速系统运行特性及能效分析

重载车辆行驶路况复杂,在其下长坡过程中,机械制动器因长时间工作而温度上升,容易造成刹车失灵。为此,针对30 t重载车辆提出一种液压再生缓速系统对其进行制动,系统由液压泵/马达为车辆提供制动扭矩,蓄能器回收制动动能并在加速工况辅助电机驱动车辆,散热模块进行系统散热。制定了车辆行驶过程中的加速与制动控制策略并建立了车辆系统仿真模型进行分析。结果表明:在不同的坡度下该系统均能够提供足够的制动扭矩,最大制动扭矩可达1150 N·m,具有很好的缓速制动特性,其系统油温也稳定在60℃左右;同时该系统能将回收的制动能量辅助电机驱动行走系统,制动能量回收率为42.4%。

电动装载机电液复合制动协同控制策略研究

针对电动装载机的电液复合制动系统,为满足多工况制动需求以及保障制动安全性,本文提出了一种基于再生制动自由行程液压制动阀的电动装载机液压制动系统。结合电动装载机的理想前后轮制动力分配曲线以及制动意图识别得到的制动强度,制定了制动强度与整车制动力矩需求的分配曲线;为进一步提高再生制动力与液压制动力分配的协调性,同时兼顾制动能量回收效率,提出了一种基于行走再生制动和液压制动的电液复合制动协同控制策略,降低了整车总制动力矩波动,保证了制动模式切换的平顺性。最后,搭建了基于AMESim-Matlab/Simulink联合仿真模型,并搭建试验样机,验证了电动装载机复合制动协同控制策略的可行性,结果表明,该系统能量回收效率可达71.6%,制动回收率可达44.5%,一个工作循环实现节能7.6%,说明本文提出的控制策略具有良好的制动性能和能量回收效率。

不同抽水转发电模式下抽蓄机组稳定性参数对比

新型电力系统建设要求缩短抽水蓄能机组的快速响应时间。以具体电站机组为例,研究了正常与快速抽水转发电模式下监控流程的主要差异和机组稳定参数的变化规律。在此基础上,引入反时限振动评价方法对两种模式下的振动峰峰值进行计算,评估了转换模式对机组的影响;采用频谱分析方法对无叶区压力脉动进行分析,发现了低转速下无叶区存在水力共振现象,并揭示了共振幅值、频率与转速的相关性。研究结果表明:抽水转发电快速流程优于正常流程,快速转换模式下的水力制动方式较正常转换模式下的电气制动加机械制动方式流程时间由438 s缩短至220 s,显著提高工况转换效率;在振动对机组损伤方面,14个振动、摆度监测点中13个监测点证明快速转换模式有利于延长机组预期寿命;同时,快速转换模式有利于机组快速通过低转速下无叶区产生的水力共振区,将水力共振时间由15 s缩减至5 s,共振转速区间压缩超过60%。

采煤机搬运车制动系统同步性优化设计

为提高采煤机搬运车制动系统的响应速度,并解决前后车制动同步性差的问题,结合仿真分析对制动系统进行了优化设计。通过计算搬运车制动效能,得出在可优化的参数中,影响制动系统响应速度的主要因素为消除制动器间隙所用时间和制动器制动力增长所用时间;建立制动系统数学模型,通过Simulink仿真计算可知,通过减小非制动工况下制动器摩擦片的间隙,可有效提高制动系统的响应速度。提出背压控制阀组以最大限度地减小摩擦片间隙,通过计算确定背压值最大为1.29 MPa,并通过试验得知背压小于0.9 MPa时,背压控制阀组几乎不起作用,同时为防止搬运车正常行驶时出现制动拖滞现象,将背压值设定为1.2 MPa。通过试验确定背压控制阀组,提高了前后车制动器响应的同步性,试验结果表明:相较于优化前,前后车制动时间差减小为0.24 s,保证了搬运车制动系统的安全运行。最后,通过试验验证了制动系统响应速度的提升,结果表明:常规制动中制动距离为5.2 m,紧急制动中制动距离为3.2 m,均符合MT/T 989—2006《矿用防爆柴油机无轨胶轮车通用技术条件》的技术要求。

能量应急与双泵供能液压制动系统研究

矿用宽体车在极端路况下频繁制动会导致整车负荷多变,造成发动机停转或制动系统压力急剧变化,导致制动系统失效。针对以上问题,提出一种带有能量应急模块的双泵供能液压制动系统。以应急蓄能器作为能量应急模块、发动机与电动机带动油泵组成双泵供能模块为系统供能,具有紧急制动、行车制动等制动方式。对能量应急与双泵供能液压制动系统和传统单泵供能系统进行对比,在AMESim中建立系统仿真模型。结果表明:相比传统单泵供能系统,双泵供能系统首次充液时间减少了0.98 s,能量应急模块与双泵供能模块可相互亢余,保证系统液压油供给;同时中后桥制动响应时间比前桥慢了0.03 s,进一步提高了整车制动稳定性;系统可实现矿用宽体车行驶中的紧急制动。