半环面牵引式无级变速器性能研究

摘要

随着发达国家环保部门(EPA)颁布了汽车燃油经济性和排放的新标准，无级变速传动(CVT)成为了提高汽车内燃机(ICE)燃烧效率的关键技术之一。对汽车界来说，通常采用的无级变速传动如各种不同的带式无级变速传动并不是新东西，然而其承载能力受到限制。随着材料、传动油、制造技术以及控制技术的发展，出现了承载能力更大、速比调节响应更快的环面牵引式无级变速器，这种变速器可用于大排量的车辆动力传动系统中。 本文针对半环面牵引式CVT的工作特性进行了理论和实验研究，提供了一套这种机械传动的设计方法。研究了动力传动单元之间的接触特性，其接触为典型的椭圆形点接触，并在弹性流体动力润滑作用下的接触区域内，通过高接触压力下的油膜剪切力来传递动力。对不同系统参数下的赫兹接触应力进行了研究，并以图表形式给出了最大赫兹应力与速比的关系。得出了材料性能(弹性系数)、工况条件(输入扭矩和最大牵引系数)和几何参数(曲面盘几何比，曲率比和动力滚轮的半锥角)对该传动的性能有重要影响的结论。这些图表为设计者了解最大赫兹应力提供了依据，从而更好地应用于特定工况下接触表面间的牵引力分析。 建立了半环面牵引式CVT(共轴和平行轴)的系统数学模型，详细分析并计算了它的扭矩传递能力、由自旋运动及几何滑动产生的功率损失、椭圆形接触区的接触效率，并以积分形式表达了其结果，这样就能用数值方法方便地进行设计计算。整个分析过程在接触区内赫兹参数的运动学关系及其表达式的基础上进行。提出了在系统参数的影响下半环面牵引式CVT中特有的自旋点接触效率的计算方法。以图表的形式展示了主要参数(加载后的接触应力，滚轮的几何比和传动比)的数值计算结果，这些参数对系统的性能有重要影响。这些图表有助于设计人员选择合适的系统参数以减少不必要的自旋功率损失。 开发了系统实验台，为调节系统速比提出了一种新的机构。用不同类型的润滑油(无级变速器油和牵引油)进行了不同速比、输入扭矩和转速下的实验，并对所设计的牵引传动系统的实际性能进行了评价。 整个测量单元与实验装置构成为一体，采用恰当的测量仪器对不同工况下的转速和扭矩传递能力进行了测量。 实验结果表明，传动效率主要取决于工况条件，随输入转矩、输入转速和传动比以及传动油的不同而不同。 结果表明，与Ub3牵引油和其它的无级变速传动油(CVTF)相比，使用Ub4牵引油的传动系统具有更高的传动效率。因此，对于半环面牵引式无级变速传动(CVT)，本文推荐使用Ub4牵引油。

目录

文摘

英文文摘

CHAPTER 1 INTRODUCTION AND REVIEW OF RELEVANT LITERATURE

1.1 Introductory Remarks

1.2 Continuously Variable Transmissions (CVTs)

1.3 Toroidal CVTs

1.3.1 Single cavity toroidal

1.3.2 Dual-cavity toroidal

1.4 Backgrounds and History of Toroidal Type CVTs

1.4.1 Early developments

1.4.2 Modern developments

1.4.3 New developments

1.5 Current Problem and Research

1.6 Thesis Organization

CHAPTER 2 TOROIDAL TRACTION CVT CONCEPT

2.1 Overview

2.2 General Kinematics of Stepless Traction CVT

2.2.1 Spinning and rolling velocities

2.2.2 Spin roll ratio

2.2.3 Spin ratio

2.2.4 Spin point and geometric slippage

2.2.5 Speed ratio under loaded condition

2.2.6 Relative slip

2.3 EHL Point Contact with Variable Local Sliding Velocities and Oil Film Thickness

2.4 Determination of the Torque Capacity

2.5 Power Loss and Contact Efficiency of Traction CVT

2.6 Basic Structures of the Toroidal CVT

2.6. I Geometrical particularities of full toroidal CVTs

2.6.2 Geometrical particularities of half toroidal CVTs

2.7 Features of Toroidal CVTs

2.7.1 Features ofhalftoroidal CVTs

2.7.2 Features of full toroidal CVTs

2.8 Half Toroidal CVT

2.8.1 Geometry and operation principles

2.8.2 Transmission ratio

2.8.3 Hydraulic system

2.9 Methods to Generate Contact Force

2.9.1 Hydraulic system

2.9.2 Mechanical system

2.10 Contact Pressure at Traction Contact Point

2.11 Power Transmission

2.11.1 Principle of power transmission for toroidal CVT

2.11.2 Effective traction coefficient

2.12 Necessary Loading Force for Traction Drive

2.13 Traction Power Transfer Technologies

2.14 Ratio Change Principle for Half toroidal CVT

2.14.1 Formulation sideslip for speed ratio change

2.14.2 Creep effect

2.14.3 Formulation of creep and sideslip

2.14.4 Modeling of traction force and sideslip force

2.15 Spin Analysis

2.15.1 Spin at traction surface

2.15.2 Traction force recession and moment loss by spin

2.15.3 Heat flux flow in the power roller

2.16 Torque Transmission Efficiency of the Half Toroidal CVT

2.16.1 Torque loss of support bearing

2.16.2 Torque transmission efficiency

CHAPTER 3 DESIGN METHOD OF HALF TOROIDAL CVTS

3.1 Introduction

3.2 Principal of Operation

3.3 Specifications

3.3.1 Input data

3.3.2 Material

3.3.3 Traction oil

3.3.4 Dimensions

3.4 Design Calculation for Loading Cam Mechanism

3.4.1 Lead cam

3.4.2 Cam angle

3.4.3 Axial load

3.4.4 Tangential load

3.4.5 Contact force

3.4.6 Maximum contact stress on the cam surface

3.4.7 Contact force via loading cam

3.5 Basic Geometry and Kinematic Relations

3.5.1 Basic dimensions

3.5.2 Ideal speed ratio

3.5.3 Transmission ratio

3.5.4 Power roller speed

3.5.5 Speed ratio range

3.6 Forces Analysis on the Input disk, Power roller and Output disk

3.6.1 Force analysis on input disk

3.6.2 Force analysis on output disk

3.6.3 Force analysis on power roller

3.7 Strength Calculations

3.7.1 Traction contact point

3.7.2 Maximum contact stress at contact ellipse

3.8 Force Analysis on Gears and Shafts

3.8.1 Force analysis on spur gears

3.8.2 Reaction forces and bending moments

3.8.3 Shaft design and bearing selection

3.9 Oil Film Thickness and Oil Film Parameter

3.9.1 Oil film thickness

3.9.2 Oil film parameter

3.10 Spin Analysis

3.11 Summary

CHAPTER 4 THEORETICAL ANALYSIS ON HALF TOROIDAL CVTS

4.1 Introduction

4.2 Coaxial Half Toroidal CVT

4.2.1 Kinematic relations of coaxial half toroidal CVT

4.2.2 Performance analysis of coaxial half toroidal CVT

4.2.3 Search for spin point locations of coaxial half toroidal CVT

4.3 Parallel Axle Half Toroidal CVT

4.3.1 Kinematic relations of parallel axle half toroidal CVT

4.3.2 Performance analysis of parallel axle half toroidal CVT

4.3.3 Search for spin point locations of parallel axle half toroidal CVT

4.4 Theoretical Results and Discussions

4.4.1 Theoretical results for the Hertzian parameters of coaxial half toroidal CVT

4.4.2 Theoretical results for torque capacity and contact efficiency of coaxial half toroidal CVT

4.4.3 Theoretical results for torque capacity and contact efficiency of parallel axle half toroidal CVT

CHAPTER 5 EXPERIMENTAL INVESTIGATIONS OF HALF TOROIDAL CVTS

5.1 Introduction

5.2 Test Rig Description

5.2.1 Experimental setup

5.2.2 Measurement setup

5.3 Experimental Procedure

5.4 Experimental Results and Discussions

5.5 Summary of the Experiments

CHAPTER 6 CONCLUSIONS AND FUTURE WORK

6.1 Summary and Findings

6.2 Future Work Suggested

ACKNOWLEDGMENTS

REFERENCES

APPENDICES 1 List of publication

APPENDICES 2 Attended Projects List

VITA

独创性声明和学位论文版权使用授权书