Graduation Design (Thesis) of Wuhan University of Technology

Improvement of rear leaf spring suspension for ZYP5031XXPY pure electric vehicle

(School): International Education College

Specialty amp; Class: Automobile gj 1304

Student name: Tang Fangyu

Tutor: Zhong Shaohua

Statement of Originality

I solemnly declare that the thesis I submit is a piece of writing I completed independently based on my own research under the guidance of my supervisor. Except for the quotations, this paper does not include any writings published or completed by other individuals or groups. I am fully aware that the legal consequences of this statement are borne by me.

Signature of the author:Tang Fangyu

Date:2017.0530

Copyright Letter of Authorization to The Dissertation

The author of this dissertation fully understands provisions stipulated by this school on keeping and using dissertations. The author agrees that the school can reserve and send photocopies and electronic versions of this thesis to relevant departments or institutions managing dissertations. This thesis can be read and borrowed. I hereby authorize excellent provincial institutions appraising bachelor dissertations to incorporate all or any part of this dissertation into relevant databases for retrieval, as well as to preserve and compile this dissertation by photocopying, scanning or reprinting it in a reduced format.

This dissertation is: 1. Confidential until(year) and then this authorization letter will apply. 囗

2. Non-confidential. 囗

Signature of the author: Tang Fangyu

Date:2017.0530

Signature of the tutor:

Date:

Abstract

Suspension is one of the important components of the car, is the frame and axle between all the force connection device in general.Its role is to tansmit the force and torque from the road work on the wheel to the frame, to ensure the normal driving of the car.At the same time eases the impact when driving due to the uneven pavement caused by cars,and attenuate vibration,to ensure the comfort of passengers and car ride comfort.

This paper mainly completes the improved design of the steel plate spring suspension of ZYP5031XXPY pure electric vehicle.At first of the design,we should understand the present situation and development direction of the electric vehicle suspension and summary the structural classification and design requirements of the suspension.Then determine the direction of improvement towards light weight and car ride comfort,change the multi-piece leaf spring into small pieces.The rear suspension is a small piece of variable cross section steel leaf spring non-independent suspension.And finally complete the design and calculation of the parameters of the suspension components.we should first grasp the ZYP5031XXPY pure electric vehicle suspension main performance parameters when calculating,Including wheelbase, load, dynamic deflection, deflection and so on.Then design and calculate the suspension elastic element,Including determination of plate spring length, width, thickness, and the number of pieces.And then design other small parts and check their strength.Finally, analyze the design content and results,and use CATIA and other mapping software to complete assembly drawings and parts of the drawing of Rear plate spring suspension of the ZYP5031XXPY pure electric vehicle after being improved.

Key words:Plate spring suspension;Independent suspension;electric car;Structural design

Content

1.Preface 1

1.1.Development Status and Prospect of Electric Vehicles 1

1.2.The problem of this car suspension 2

1.3.The purposeand and the design requirements of the suspension study 2

1.4.The main problem that should be solved in this design 3

2.Determine the suspension structure 4

2.1.The composition of the vehicle suspension and the role of each component 4

2.2.Structure and characteristics of independent suspension and non - independent suspension 4

2.3.Determination of rear suspension system 5

3.Determination of the main parameters of the suspension 5

3.1.determination of suspension Static deflection 5

3.2. Determination of Suspension Dynamic Deflection 6

3.3.Suspension Elasticity 6

3.4.Suspension roll angle stiffness and its distribution in the rear axle 7

4.Design of suspension elastic elements 7

4.1. Selection of steel plate spring type 7

4.2. Determination of steel plate spring material 8

4.3. Plate spring full load arc height 9

4.4. Determination of the length of the leaf spring main leaf 9

4.5. Determination of the number of leaf springs 10

4.6. Determination of cross-sectional shape and number of steel plates 10

4.7.Calculation of steel plate spring stiffness 10

4.8. Determination of maximum stress point and stress calculation of leaf spring 13

4.9. Check the strength of the leaf spring 16

5.Design of shock absorbers 17

5.1. Classification and selection of shock absorbers 17

5.2. Relative damping coefficient 18

5.3. Determination of damping coefficient of shock absorber 19

5.4. Determination of maximum unloading force 20

5.5. Determination of the diameter D of the cylinder of the drum shock absorber 20

Summary 21