摘 要

本文设计了磁流变阻尼器外加滚珠丝杆式的馈能装置，磁流变阻尼器的活塞杆上下运动，滚珠丝杆将上下运动转化为发电机输入轴的旋转运动，这样将汽车垂直振动的能量转化为电能储存在电池组中，以提升电动汽车的续航里程。

论文主要研究了磁流变阻尼器结构设计，也设计了滚珠丝杆式的馈能装置。本文一方面借助Maxwell 2D有限元分析模块，对所设计的磁流变阻尼器内部磁路中的磁感应强度和磁力线进行模拟，并与实际工况下所需求的磁感应强度进行对比。另一方面借助电磁学理论，从电磁学角度计算磁流变阻尼器阻尼通道中的磁感应强度。

从以上两个方面的研究结果表明：所设计的磁流变阻尼器内部磁路符合要求

本文的特色：设计了馈能型磁流变阻尼器。从理论计算和有限元分析两个方面验证磁路的有效性。并建立了馈能型磁流变阻尼器的力学模型，这对研究半主动悬架具有重要的指导意义。

关键词：磁流变阻尼器；有限元分析；磁感应强度；馈能装置；力学模型

Abstract

This paper designs a magnetorheological damper with a ball screw type energy-feeding device. The piston rod of the magnetorheological damper moves up and down. The ball screw converts the up and down motion into the rotary motion of the generator input shaft. The vibration energy is converted into electrical energy and stored in the battery pack，so as to achieve the purpose of improving the cruising range of electric vehicles.

The thesis mainly studies the structure design of the magnetorheological damper, and also designs a ball screw type energy feeding device. On the one hand, this paper uses the Maxwell 2D finite element analysis module to simulate the magnetic induction intensity and magnetic field lines in the internal magnetic circuit of the designed magnetorheological damper, and compares it with the magnetic induction intensity required under actual working conditions. On the other hand, with the help of electromagnetic theory, the magnetic induction intensity in the damping channel of the magnetorheological damper is calculated from the perspective of electromagnetics.

The research results from the above two aspects show that the internal magnetic circuit of the designed magnetorheological damper meets the requirements

Features of this article: Design the energy-feeding magnetorheological damper. Verify the effectiveness of the magnetic circuit from theoretical calculation and finite element analysis. And establish the mechanical model of the energy-feeding magnetorheological damper, which has important guiding significance for the study of semi-active suspension.

Key words: Magnetorheological damper; Finite element analysis; Magnetic induction intensity; Energy feeding device; Mechanical model

Contents

Chapter 1 Introduction 1

1.1 Research status at home and abroad 1

1.1.1 Automotive suspension system 1

1.1.2 Magnetorheological fluid 1

1.1.3 Magnetorheological damper 2

1.1.4 Energy-fed suspension system 3

1.2 The basic content of the research 5

Chapter 2 Working Principle and Structural Design of Magnetorheological Damper 7

2.1 Working Principle of Magnetorheological Fluid 7

2.2 Structure selection of magnetorheological damper 8

2.3 Working principle of magnetorheological damper 10

2.4 Structural parameter design of magnetorheological damper 11

2.4.1 Inner diameter of cylinder 13

2.4.2 The diameter of piston rod 13

2.4.3 Performance parameters of magnetorheological fluid 13

2.4.4 Preliminary determination of the working gap width 14

2.4.5 Length of damping channel L 14

2.4.6 Calculation of maximum damping force 14

2.5 Magnetic circuit design of magnetorheological damper 15

2.5.1 Material selection 15

2.5.2 Calculation of magnetic circuit structure parameters 16

2.5.3 Electromagnetic coil design 18

2.6 Finite element analysis of the magnetic circuit of the magnetorheological damper 22

2.7 Structure selection of energy feeding device 29

2.8 Select the product model of the ball screw 30

2.9 Summary of this chapter 33

Chapter 3 Mechanical Model of Energy-Feed Magnetorheological Damper 34

3.1 Theoretical basis 34

3.1.1 Biot-Savart Law 34

3.1.2 Bingham model 35

3.2 Relationship between magnetic field strength in the damping channel and the current in the coil 35

3.3 Deducing the damping force formula from the bingham model 37

3.4 Mechanical model of energy feeding device 38

3.5 Mechanical model of energy-feeding magnetorheological damper 40

3.6 Energy recovery model of magnetorheological damper 40

3.7 Summary of this chapter 40

Chapter 4 Summary and prospect 42

4.1 Summary 42

4.2 Prospect 42

References 43

Thanks 45

Chapter 1 Introduction

1.1 Research status at home and abroad

1.1.1 Automotive suspension system

Suspension is the general name for all force transmission connection devices between the frame (or load-bearing body) and the axle (or wheel). The performance of automobile suspension system will significantly affect the car's handling stability and ride comfort. The stiffness and damping of traditional suspension systems are determined according to experience or optimized design methods. The performance parameters of this passive suspension system are constant during driving. If the stiffness and self-damping characteristics of the suspension system are dynamically adaptively adjusted according to the driving conditions of the car, so that the suspension system is always in the best shock absorption state, it is called an active suspension.

Active suspension is divided into full active suspension and semi-active suspension. Full active suspension is mainly used in luxury cars, which requires many sensors, has a complicated structure, and is expensive. The semi-active suspension does not consider changing the stiffness of the suspension, but only changes the damping of the suspension, so it is composed of no power source and only controllable damping elements. The semi-active suspension has a simple structure, consumes almost no vehicle power when working, and can obtain similar performance to a full-active suspension, so it has a good application prospect ^[1].

1.1.2 Magnetorheological fluid

Magnetorheological fluid is a controllable fluid, and it is one of the most active researches in smart materials. A magnetorheological fluid is a suspension made of a mixture of tiny soft magnetic particles with high magnetic permeability and low hysteresis, and a non-magnetic liquid. Under the condition of zero magnetic field, this suspension exhibits the characteristics of Newtonian fluid with low viscosity; while under the action of strong magnetic field, it exhibits the characteristics of Bingham with high viscosity and low fluidity. This characteristic of the magnetorheological fluid makes it used in many active and semi-active control devices to produce intelligent, flexible, efficient, environmentally friendly and energy-saving equipment. It has been applied in many industries and has shown a wide range of applications.

Rainbow first proposed the concept of magnetorheological fluid in 1948^[9]. It is a suspension formed by dispersing micron-sized magnetically polarized particles in a non-magnetic liquid (mineral oil, silicone oil, etc.). Under the condition of zero magnetic field, the magnetorheological fluid behaves as a liquid with good fluidity, and its apparent viscosity is very small; under the action of a strong magnetic field, the apparent viscosity can be increased by more than two orders of magnitude in a short time (millisecond order), and presents Solid-like properties; and this change is continuous and reversible, that is, the original state is restored after removing the magnetic field. However, from the 1950s to the 1980s, the development of magnetorheological fluids has been very slow due to the failure to recognize the potential of its shear stress and the problems of suspension and corrosion. Into the 1990s, with the improvement of preparation technology, the research of magnetorheological fluids has renewed, and has become an important branch of the current intelligent materials research field^[2].

1.1.3 Magnetorheological damper

A magnetorheological damper made of magnetorheological fluid is a kind of damper with adjustable damping force and excellent performance. The piston assembly of the MR damper introduces a circuit. When current passes through the damper, the coil in the piston generates a magnetic field and instantly changes the characteristics of the magnetorheological fluid in the piston. In this way, the damping force can be continuously changed in real time by adjusting the damper current. However, the magnetorheological damper has the problem of static settlement of the magnetorheological fluid, which restricts his development. According to the manner in which the magnetorheological fluid flows in the cylinder of the damper, the magnetorheological damper can be divided into a shear type, a valve type, a shear valve type, and a squeeze flow type.

The advantages of MR dampers are simple structure, good reliability, and fast response speed, which make up for the shortcomings of traditional dampers such as the non-adjustable damping force and poor vibration isolation performance. Therefore, MR dampers have a wide range of applications in the engineering field. China's first three-tower cable-stayed bridge—the Dongting Lake Bridge ’s cable-stayed cable vibration control uses MR dampers to achieve effective shock absorption^[3]. Zhang Hongbo et.al. installed a total of 20 viscous shear-type MR dampers in Zhaobaoshan Bridge, Ningbo, which effectively controlled the wind-induced vibration of stay cables ^[4]. Zheng Ling and others equipped MR dampers on military armored vehicles. The experimental results showed that the average off-road speed of armored vehicles was increased by 25%, and the acceleration of pitch-roll was reduced by 30%, and the ride comfort and steering stability were improved^[5]. In 2002, Delphi applied magnetorheological dampers to Gadillac series cars for the first time, which significantly improved the car's ride comfort and operating stability. Magnetorheological damper has a good application prospect in the field of vehicles.