1．目的及意义

Atpresent, with the continuous growth of the market economy and in response tothe call for environmental protection, new energy vehicles are occupying anever-increasing share of the world market. Electric trucks, as a naturally partof new energy vehicles, are greatly concerned by various companies.

Electrictrucks are economical, with lower charging fees than fuel costs. Becauselogistics vehicles value cost economy and require less comfort, electricvehicles are economically superior to ordinary fuel trucks. From the point ofview of car purchase cost, electric logistics vehicles not only enjoy centraland local double subsidies, but also have purchase tax exemption when buyingcars. However, the high original price may lead to higher selling prices thantraditional logistics vehicles, but in general, electric vehicles with lowcharging costs have obvious economic advantages.

Accordingto the research report on the current situation of China's electric logisticsvehicle market from 2018 to 2025 published by the China Industry ResearchNetwork, many large cities do not limit the green light of pure electricvehicles, but also give priority to licensing and free parking. Compared to those fuel trucks which can onlybe used at night, pure electric trucks can work at anytime and in anywhere, whosecompetitive advantage is obvious. In U.S. and UK, electric trucks are alsobecome more and more popular, as U.S. is building charging sites for electrictrucks^[1] , andelectric trucks are occupying an increasing share of the U.S. market^[2], UK is trying to replace ordinary trucks by electrictrucks for sanitation workers^[3]. Above all, we can clearly see the bright future ofelectric trucks.

At thesame time, electric trucks have the characteristics of no pollution, low noise,high energy efficiency, simple structure, easy maintenance and so on, and these advantages are in line with thecurrent market requirements; however, electric vehicles are not as good as theysee, especially the short battery life and low energy storage, which lead tounsatisfactory mileage after a single charge^[4]. However, from a developing point of view,with the advancement of science and technology, the problems of electricvehicles will be gradually solved ^[6], and electric vehicles will be widespread,as Ford company^[7] andTesla company^[8]， both are big and famous companies in the world， are trying to research new technology for electric trucks, andthere will be more and more companies starting their research and developmentfor electric trucks. With the development of technology, their prices and usecosts will decrease ^[10].

Sincebraking performance is an important indicator of a car, which is directlyrelated to traffic safety, and many terrible traffic accidents are often causedby long braking distance and side slips during emergency braking. Therefore,braking performance of a car, especially a truck, is an important guarantee forsafe driving, also the core part of my design. In this design, I will try todesign the rear brake for Type 1070 electric truck to guarantee its brakingability. For the accuracy and practicality of this design, I’d choose DongfengEQ1070 TTBEV pure electric truck to search for related data and finish mydesign.{title}

2. 研究的基本内容与方案

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Thebasic content of this design is to design the rear wheel brake of the 1070electric truck. I intend to use Dongfeng EQ1070 TTBEV as the design model. Themain contents of the design are listed as follows:

1.Determinethe type of designed brake；

2.Determinethe structure of designed brake；

3.Obtainthe corresponding data from the design model for calculation；

4.Checkin the relevant performance；

5.Drawthe required design drawings.