摘 要

悬架系统是车辆的重要组成部分，其重要作用是连接簧上质量和簧下质量，从而合理传递路面激励，以保证车体部分有良好的平顺性。传统油气式减振器通过节流孔以及油液的粘滞阻尼产生阻尼力，并通过产生的热量将悬架部分的能量耗散掉。经研究发现，一辆中型轿车在一般路面上以96km/h的速度行驶，悬架耗散能量可达400W。如果能够将这一部分能量经过合理的设计进行有效的收集，则能够为车辆悬架的主动控制提供能源，实现悬架主动控制的能量自供给，甚至能为车辆的电控系统提供辅助能源，成为车辆节能减排的新途径。

经过多年的研究，目前能量回收式悬架可根据发电机的类型分为直线电机式和旋转电机式。而旋转电机式能量回收悬架还可以进一步划分为机械传动式和液压传动式。本论文依托国家自然基金面上项目（项目编号：51675391）“并联互通液电馈能式主动径向转向架理论及试验研究”，对液电馈能型能量回收式悬架进行了核心零部件的三维模型设计、加工和理论研究，重点讨论了综合考量乘坐舒适性、操纵稳定性和能量回收特性的多目标情况下，等效转动惯量取值的优化，具体研究工作如下：

1）对液电馈能式减振器的理论模型进行了推导，基于推导的理论模型建立了仿真模型并对其外特性进行了分析。首先分析了液电馈能式减振器的工作原理，并基于液体体积的连续方程逐步推导了流经每个单向阀的液体体积、流经高压蓄能器和低压蓄能器的油液体积、液压马达和发电机之间的的扭矩平衡方程以及减振器作用力的表达式。基于所述的理论推导，借助Matlab中的Simulink模块里内置的PTO-sim模型库建立了液电馈能式减振器的仿真模型，并分析液电馈能式减振器的常用车型及其对应工况下的激励对模型进行了仿真分析。分析仿真结果发现液电馈能式减振器在定幅值变频率和定频率变幅值的激励作用下，减振器的作用力随频率和幅值的增加而增加，并且，在低频/低幅值的作用下，示功图左右以及上下均基本对称，而当激励逐渐增大之后，示功图开始出现倾斜，且激励的频率越大，倾斜程度也越大，并且倾斜的方向均保持基本一致，由此发现了滞后性是液电馈能式减振器的重要特性。而对于其能量回收特性，平均功率变化范围从10W到200W不等，最高可超过300W。并且，液电馈能式减振器对频率的变化较为敏感，而对幅值的变化则相对不敏感，最终得出液电馈能式减振器更适用于路面激励变化相对较小的轨道车辆的结论。

2）设计了液电馈能核心模块的三维模型，并根据设计对核心模块进行了加工和组装。首先通过对液电馈能式减振器的工作原理分过程进行了仔细分析，然后对液压系统的工作环境压力、最大液压流量、单向元器件的开启压力等工况进行了分析。为了将液电能量转换核心模块进行高度集成，逐步分析了其各个状态下的油液流动情况，初步设计了草图并对草图的设计原理进行了逐步分析，发现草图能够满足液电馈能式减振器的相关工作要求，可根据该布置简图进行各零部件的细节设计。设计的液电能量转换模块分为两横两纵两个主体，其中横向主体内置油液通道，并且预留单向阀组、高压蓄能器、低压蓄能器以及液压马达的接口，而纵向主体则包含单向阀组与进出口端接口。建模的过程分为横向主体、纵向主体、单向阀组以及各部分的连接装配关系。最终，根据设计的三维模型对液电能量转换核心模块进行了加工与组装。

3）建立液电馈能型馈能悬架1/4车模型，并对1/4车模型的动力学特性进行了理论分析，并创新性的采用等效电路的方法建立了仿真模型。为探究液电馈能型能量回收式悬架对车辆动力学特性及能量回收特性的影响，需对配备液电馈能型能量回收式减振器的馈能悬架建立二自由度四分之一车模型。为简化模型，将摩擦阻尼和高压蓄能器的影响统一等效为液压阻尼，然后基于简化模型对四分之一车模型的平顺性（乘坐舒适性和操纵稳定性）和能量回收特性的理论关系进行了推导，研究发现当等效惯容小于某一特定值时，能量回收式悬架的乘坐舒适性将优于传统悬架。并且，等效惯容的影响因素主要有悬架系统的刚度与轮胎刚度的刚度比以及簧上质量与簧下质量的质量比。而对于操纵稳定性，能量回收式悬架在刚度比较大的情况下能够提高车辆的操纵稳定性。在建立模型方面，则分析了振动模型和电路模型的转换方法，然后在Matlab中的Simulink模块下建立了直观、简明的等效电路模型。

4）基于仿真模型进行了馈能悬架1/4车模型动力学仿真分析，并通过仿真结果和理论推导结果对1/4车二自由度车模型的动力学特性进行了分析。首先根据液电馈能减振器的外特性对仿真所采用的车辆参数和路面激励参数进行了分析和选定，然后基于选定的参数对于特定车型在两种常见的路面激励情况下的操纵稳定性、乘坐舒适性和能量回收特性进行了仿真，并对仿真结果进行了仔细的分析。通过对比分析可知，第三章的理论分析正确。即在不同的工况下，车辆的乘坐舒适性不同，但是液电馈能型能量回收式悬架相对于传统油气式悬架改善乘坐舒适性的范围都是不受路面激励的变化影响，并且对于选定的车型，液电馈能型能量回收式悬架的等效惯量改善乘坐舒适性的范围大于改善操纵稳定性的范围。

5）基于仿真模型并借助多目标优化软件Isight进行联合仿真，对液电馈能型能量回收式悬架的等效惯量进行了多目标优化设计。基于第三章的理论推导和第四章的四分之一车二自由度动力学模型的仿真分析结果可知，液电馈能型能量回收式悬架能够在回收传统油气式悬架耗散的能量的同时，能够在一定范围内提高操纵稳定性和乘坐舒适性。因此，对于等效转动惯量的优化是一个单变量三目标的多目标优化。对多目标优化的背景进行了概述，然后根据液电馈能型能量回收式悬架的优化特点选择了多目标粒子群算法（Multi-Objective Particle Swarm Algorithm）作为优化算法，并逐步在多目标优化软件Isight中建立联合仿真模型进行优化，最终得到了目标情况下的最优解。

关键词：液电馈能型能量回收式悬架；车辆动力学；能量回收；多目标优化；多目标粒子群算法

Abstract

Suspension System is the key component for vehicles, one of its import function is to connect the sprung mass and un-sprung mass and transform the excitation from road in order to achieve good riding comfort and road handling. Traditional viscous absorber dissipates this part of energy as heat by its orifices and viscous damping. Based on previous research, a kind of medium-sized vehicle can dissipate about 400W energy in suspension system under the speed of 96km/h. If this part of dissipated energy can be harvested by rational design, the harvested energy can support the energy consumption of active control and realize self-powered of active control, and even can provide auxiliary energy for electronic control system, which can be a new approach to realize energy conservation and emission reduction.

After a long period of research, the energy harvesting suspension system can be divided into linear-motor type and rotary-motor type, and the rotary-motor type can be divided into mechanical transmission and hydraulic transmission. This paper is based on the project funded by National Science Founding of China (NSFC)—“Theoretical and Experimental Study of the Parallel Interconnection Hydraulic-Electric Energy-Harvesting Active Radial Steering Bogie System”（Project No. 51675391）. In this paper, the 3D model of the key components for converting hydraulic energy into electric power has been designed and fabricated. This paper is focused on the multi-objective optimization of the equivalent inerter considering ride comfort, road handling and energy harvesting, the specific research can be seen below.

1) The theoretical model of Hydraulic-electromagnetic Energy-harvesting Shock Absorber (HESA) has been derived, and the external characteristics of HESA have been analyzed. Firstly, the working principle of HESA has been analyzed, and the formulas of fluid volume flowing each check valve, fluid volume flowing high pressure accumulator and low pressure accumulator, torque between hydraulic motor and generator have been derived based on continuity equation of hydraulic volume. Based on aforementioned theoretical analysis, the simulation model has been built in PTO-sim library of Simulink in Matlab. Simulations have been down based on typical vehicle model and its corresponding excitation. The results show that under the excitation of fixed-frequency/ variable-amplitudes or fixed-amplitude/variable-frequencies, the force from HESA will increase with the increase of frequency or amplitude. What’s more, the indicator diagram is symmetrical in both up-and-down and right-and-left, but the indicator diagram will incline with the increase of excitation, and the larger the excitation is, the more incline it will be. This kind of characteristic shows that hysteresis is one of the importent characteristics of HESA. As for energy harvesting characteristic, the mean power ranges from 10W to 200W, and the peak can reach 300W. Based on all the aforementioned simulation, we can know that the HESA is more sensitive in variable frequencies than variable amplitudes, and the HESA is more suitable for railway vehicles for its less variable excitation.

2) The 3D models of key-components of HESA have been designed and fabricated. Firstly, the working principle has been analyzed, and the ambient pressure of the hydraulic system, max flow, cracking pressure of check valves have been analyzed. In order to highly integrate the key components of HESA, the sketches of key components have been analyzed and designed, which can meet the requirement of HESA. The designed model is consisted by two horizontal parts and two vertical parts, and there are oil tracks in horizontal parts, reserved interfaces for check valves, high-pressure as well as low pressure accumulators and hydraulic motor in horizontal parts; there are reserved interfaces for check valves and in-and-out ports in vertical parts. At last, the designed 3D model has been machined and fabricated.

3) The quarter car model of this energy harvesting suspension system have been built and the dynamic characteristics of this quarter car model have been analyzed theoretically, and the model has been built by equivalent electric model. 2-DOF quarter car model is used for analyzing the suspension performance of HESA. The viscous damping and damping from high pressure accumulator have been simplified as hydraulic damping. And then, the theoretical relationships of ride comfort and road handling have been derived by simplified quarter model. It’s found that the ride comfort and road handling can be improved than traditional viscous suspension when the equivalent inerter is less than a certain value. The methods for converting vibration model into equivalent electric model have been introduced and the equivalent electric model has been built in Simulink of Matlab.

4) The dynamic characteristics of 2-DOF quarter car model have been analyzed based on simulation results. The parameters in simulation have been analyzed and selected based on the external characteristics, then, simulations for ride comfort and road handling have been done under two usual road excitations based on selected parameters. The conclusions of theoretical analysis in Chapter 3 can be proved to be true by the simulation results. That means that the ride comfort and road handling can be different in different working conditions, but the range of improvement on ride comfort and road handling of HESA than traditional viscous suspension system will not be affected by road excitation. What’s more, the improvement range of equivalent inerter of HESA on ride comfort is larger than road handling.

5)Multi-Objective optimization has been done for equivalent inerter of HESA by joint simulation of Matlab and Isight. Based on the conclusions in Chapter 3 and Chapter 4 of 2-DOF quarter model, the HESA has been proved that can harvest energy which dissipated by traditional shock absorbers as heat and as well as improve the ride comfort and road handling. Hence, multi-objective optimization has been done based on one variable and three objectives. The background of multi-objective optimization has been introduced, and Multi-Objective Particle Swarm Algorithm has been chosen based on its characteristics.