摘 要

取力器常见于汽车上的使用，由于取力器的使用可靠性与经济性能，被广泛应用在重型商用汽车上，此次设计中，针对重型商用汽车上的取力器结构进行设计。首先查阅大量文献，了解取力器的国内外研究现状并确定本文的主要研究内容，通过文献的的查阅，确定取力器的结构与工作原理。其次，根据重型商用汽车的性能要求对取力器的关键参数进行设计计算与强度校核。本文的设计思路为首先设计取力器的设计方案，然后根据重型商用汽车的性能要求对取力器的齿轮传动与轴、轴承等关键零部件的设计与校核。最后完成对取力器操纵机构的设计，其中包括气缸、拨叉的计算与选取。

关键词：取力器；设计计算；强度校核；齿轮传动

Heavy commercial vehicle sandwich power take-off

Abstract: Abstract: the power take-off is commonly used in automobiles. Because of its reliability and economic performance, it is widely used in heavy commercial vehicles. In this design, the structure of the power take-off is designed for heavy commercial vehicles. First of all, consult a large number of documents to understand the domestic and foreign research status of the power take-off and determine the main research content of this paper. Through the literature review, determine the structure and working principle of the power take-off. Secondly, according to the performance requirements of heavy commercial vehicles, the key parameters of the power take-off are designed, calculated and strength checked. The design idea of this paper is to first design the design scheme of the power take-off, and then according to the performance requirements of heavy commercial vehicles, design and check the gear transmission, shaft, bearing and other key parts of the power take-off. Finally, the design of the manipulator of the power take-off is completed, including the calculation and selection of the cylinder and the fork.

Key words: power takeoff; design calculation; strength check; gear transmission

Catalogue

Heavy commercial vehicle sandwich power take-off IV

Chapter 1 Introduction 1

1.1 Background and purpose of the research 1

1.2 Research status at home and abroad 3

1.2.1 Research status abroad 3

1.2.2 Domestic research status 4

1.3 The main research content of this paper 5

Chapter 2 Design scheme and demonstration of power takeoff 6

2.1 Design requirements for power takeoff 6

2.2 Demonstration of power take-off scheme 6

2.2.1Known parameters 6

2.2.2 Scheme demonstration 7

2.3 Summary of this chapter 9

Chapter 3 design and calculation of power takeoff parameters 10

3.1 Design and check of gear transmission 10

3.1.1 Selection of materials 11

3.1.2 Preliminary design of contact fatigue strength according to tooth surface 12

3.1.3 Checking the contact fatigue strength of tooth surface 13

3.1.4 3D modeling of gears 15

3.2 PTO shaft design process 17

3.2.1The overall design of the shaft 17

3.2.2 Shaft structure modeling 18

3.2.3 Shaft strength calculation 18

3.3 Selection of power take-off bearings 20

3.3.1 Shaft force analysis 20

3.3.2 Select bearing model 20

3.4 Power take-off key connection design 21

3.4.1 Power take-off shaft slip spline 21

3.4.2 Power take-off shaft method orchid key 22

3.5 3D drawing of power take-off assembly 22

3.6 chapter summary 23

Chapter 4 Design of power take-off control mechanism 24

4.1The design principle of the control mechanism 25

4.2Calculation of cylinder 25

4.1 Shift fork 26

4.2 3D drawing of control mechanism 26

4.3 chapter summary 27

Summarize 28

References 29

Thanks 31

Chapter 1 Introduction

Background and purpose of the research

With the rapid development of society, China's logistics functions and logistics companies have developed rapidly in recent years, which also means that the demand for heavy commercial vehicles in the Chinese market will increase over time. . The rapid development of China's heavy commercial vehicles will greatly drive the development of China's automobiles, and as the market expands, China's engineering or modified vehicles will have a larger market. The rapid development of the automotive market will further stimulate the construction and maintenance of national roads, which means that the automotive industry in the domestic market regarding highway maintenance and repair will be welcomed in the market. As China has a vast territory and people's living conditions are becoming more and more abundant, curiosity about other new things will also encourage people to use logistics. And with the rise of the Internet industry, more and more people choose to shop at home without leaving home. These behaviors have greatly stimulated the development of the logistics and transportation industry. China has a vast territory, a large resource gap between North and South, different types, and different energy and local specialties. In order to facilitate the transportation of energy and materials, it will further stimulate the development of the Chinese automobile market. In addition, the long-distance transportation of energy materials from south to north requires special vehicles to develop the market. The express delivery industry in the market has developed rapidly, which has greatly promoted the demand for various transportation vehicles. These include vehicle types such as transport vehicles and refrigerated vehicles. The pace of urbanization in China is getting faster and faster. In the process of urbanization, the construction industry, environmental sanitation and other urbanization will be further developed. The country's market demand for special vehicles for urbanization will increase substantially. The market share of heavy commercial vehicles will increase significantly, and the proportion of commercial vehicles is an indicator of a country's economic development. Effective data survey shows that the proportion of commercial vehicles in Western Europe and the United States in the market is about seven-tenths, while the proportion of heavy vehicles in China is much lower than the proportion of Western Europe and the United States. This means that China intends to lag behind Western European and American countries in economic development. Nowadays, with the rapid development of China's economy, the development of heavy commercial vehicles in the market is getting better and better, the entire commercial vehicle industry will be greatly increased, and the technical level of the entire commercial vehicle has been changed for a long time. . In the future, the development of commercial vehicles will have broad development prospects. The commercial heavy-duty vehicle industry will receive a broad development and rapid development, and the product structure of commercial vehicles and their economic scale will undergo tremendous changes in the future. The automotive market has gradually transformed into commercial vehicles. Market steam. In the future, it will become a major trend in the development of domestic automobiles to customize specialized heavy-duty commercial vehicles for different user needs. The research and development of power devices in heavy commercial vehicles is of great significance.

Heavy-duty commercial vehicle power take-offs are mainly responsible for the power transmission between the car and its equipment. It is the main component responsible for power transmission. The power take-off is mainly composed of transmission gear power take-off shaft bearings and related parts such as construction. The meshing between them completes the transmission of power. The power take-off is mainly installed at the rear of the engine. It is an external power output assembly that transmits power from the engine to other power after passing through the power take-off. Different heavy commercial vehicles have different structures, so they have different requirements for the structure of power take-offs. Among them, the type of power take-offs need to be designed according to the requirements of heavy commercial vehicles, and their product specifications also occur. Various changes, and the technical field of view between different power take-offs are very different, so some fixed parameters for different heavy-duty commercial vehicle power take-offs are also different, including the rated power of the power take-off, Specific parameters such as power. At the same time, the power take-off is also a type of gear that helps the car to engage the gear. The main parts, among which the power take off gears include pneumatic gears, manual gears, hydraulic drive gears and electric gears. Pneumatic gears are mainly used for the gear shifting method of power takeoffs that are common on the market for heavy commercial vehicles. With the rapid development of automotive technology, the requirements for heavy commercial vehicles are becoming higher and higher, and the overall paper quality requirements for heavy commercial vehicles are also increasing. Among them, the lightweight requirements for heavy commercial vehicles are increasing. In the process of designing a heavy-duty commercial vehicle, the performance of the vehicle should be increased while reducing the weight of each component as much as possible. However, due to the limited internal space of heavy-duty commercial vehicles, the volume requirements for power take-offs are high, and the volume of power take-offs is required to be small. The operating power of automobiles is getting larger and larger, which requires the output power of automobile power take-offs to increase accordingly. Therefore, it is necessary to set a relatively small volume and mass for the current market requirements, but the output power is greatly Power take-off is very promising.

Power take-off is one of the important parts widely used in automobiles, which is mainly responsible for transmitting the power of the engine. Power take-offs are often used in special vehicles, which transmit the power of the engine through power take-offs to drive special equipment. With the rapid development of China's economy and technological level, more and more machinery industries produce special vehicles with their own industry characteristics. The performance of the power take-off is closely related to the reliability of the car's work, and the power take-off as a powerful function of the connection is widely valued and welcomed. Power take-offs come in a variety of types depending on the conditions of use and changes in the environment. Figure 1-1 is a picture of several common power take-offs.

Figure 1-1 Physical diagram of power take-off

Research status at home and abroad

1.2.1 Research status abroad

The power take-off is mainly used in heavy-duty commercial vehicles. It is a device responsible for power output. The power take-off is installed behind the engine and transmits power to other power outputs through the power take-off. In order to meet the requirements of the car for different environments, power take-offs with different specifications can be installed on the chassis of the car. The power take-off can be selected according to the car's use environment and usage conditions. Depending on the use of the power take-off, the vehicle can be modified to varying degrees. Among developed countries in Western Europe and the United States, there are more than 6,000 types of power take-offs used in heavy commercial vehicles or agricultural vehicles in their countries, and in Western European and American countries, the patents on power take-offs have reached 400 fast . Among them, their power take-offs are often used in special vehicles. Because the use requirements of special vehicles are very high, the requirements for power take-offs are also very high. In order to expand the automotive market in Western Europe and the United States, Western scientific research institutions and major universities have launched research on power take-offs, including many producers ’power take-off clubs will be designed based on the original power take-off Manufacturers in Western Europe and the United States will make appropriate improvements to the power take-off according to the subsequent devices connected to the power take-off. Due to the different professional vehicles installed in the power take-off, the requirements for the power take-off are different, resulting in a variety of power take-off operation methods. The common power take-off control method is pneumatic control, but it is also controlled by mechanical control and hydraulic control.

In 1998, Germany began research on power take-offs, which mainly focused on the control methods of power take-offs. Based on the original power take-off control methods, a set of designs that could be used for multiple modes of operation was designed. Program, and conduct simulation experiments on the program, the final research results show. This set of procedures can be combined with current kinetic methods to shorten the development cycle of the extractor to the greatest extent. The development of the program for the power take-off of the German university was initially limited to an analysis of a different working condition of the transmission. Later, it was gradually applied to the chassis of the car and the representative car. Different technical analyses were carried out on the working conditions.