1. 研究目的与意义（文献综述）

over the years, the use of fuel (petrol, diesel etc.) powered vehicles has contributed to the environmental pollution, which has led to serious global warming. all over the world there has been significant environmental and political motivation to reduce t pollution so as to have a clean environment. due to these issues and some other problems, electric vehicle technology (evt), as a viable solution to clean transportation, is becoming the leading development trend of most major automotive companies [1]. different from hybrid electric vehicle, the motor drives and batteries are the only power to the pure electric vehicle [2], hence traditional braking system is no longer applicable to electric vehicle, since there will be no such unit to provide vacuum or hydraulic support[3]. the mainstream technologies for the braking mechanism of electric vehicles are electro-mechanical braking and regenerative braking systems. electro-mechanical braking system is also referred to as emb.

in july 1997, siemens, a german company registered emb patent in the united states patent office. emb was first used on airplane. from the 1990s to the last century, its application on vehicles has gradually grown and has attracted a lot of research that has led to better utilization of the system. emb mainly consists of control unit, sensors and pedal simulator. the pedal simulator simulate the relationship between speeds and braking force, sensors control running state, driving state and braking state of the vehicle. the control unit, as the main part of the whole emb, is responsible for receiving and analyzing the signal and respond accordingly[4]. emb does not only solves the problem of brake force, but also resolve the issues of anti-lock braking system, vehicle braking system, electronic stability control and driver control system which are integrated into a complex braking system. however, since emb system is a new technology, it has some challenges, such as the fault processing, temperature control, anti-interference ability, comprehensive control and high cost[5]. the companies that participate in the market competition of emb mainly include continental teves, siemens, bosch, eaton, allied signal, delphi, varity lucas, and hayes.

regenerative braking system is another popular technology, which was first developed by a frenchman called m.a. darracq in 1897. regenerative braking system is also known as feedback braking system. the operating principle is by converting the motoring action into generating action. when the vehicle brake is applied, regenerative braking system converts the vehicle kinetic energy into electrical energy and stores it. in the braking process, the control system operates according to the brake pedal stroke, speed and acceleration. the road conditions also have effect on the determination of the regenerative braking force. the ratio of regenerative braking force and friction braking force, provides more regenerative braking force to motor to meet the needed braking action[6]. on the contrary the traditional braking system can not accurately control the wheel braking force, it cannot form a good match with feedback braking system[7],so traditional braking system is not effective for recovery of braking energy.

2. 研究的基本内容与方案

The main objective of this project is to design a braking system of electric maintenance engineering vehicle working in subterranean tunnel. The mainly work environment of the target tunnel maintenance engineering vehicle is subterranean tunnel, road conditions and temperature are stability, but the road is narrow. The work of the vehicle is transporting stall and towing another vehicle with articles.

Technical Proposal:

The overall design scheme:

1. The electric engineering vehicle has a low speed, low in quality and small in size, but has a stable driving condition. Intend to remove emergency braking system and auxiliary braking system to reduce the space, weight and cost of the braking system.

2. Intend to use permanent magnet synchronous motor because it is small in size, light in weight and highly efficient.;

3. The engineering vehicle requires small size, therefore, I intend to use electro-mechanical braking system to achieve the small volume and compact structure. Optimize the brake pedal structure design according to the vehicle structure[14];

4. The electric engineering vehicle can be driven in dual direction and unmanned, Therefore it will need two cab and relative control circuit[15], intend to use a joystick as the control mechanism;

5. Less braking efficiency needed, so disk brakes will be used to obtain the small size, relatively high quality and stable performance;

6. The electric engineering vehicle has high requirements on the spatial structure, seldom brake in the running process ,therefore, it will be decided whether to bring in regenerative braking system according to the actual situation.

Design line:

1. To analyze electric vehicle braking system both domestic and foreign, compare it with the existing braking system,and select the appropriate types of brake;

2. To determine the design scheme of the brake system according to the standard requirements;

3. To analye and calculate the relevant design parameters of braking system and proofread;

4. To determine the parameters of the relevant parts of the braking system with the intention of meeting the standard requirement;

5. CATIA 3D model of the braking system will be used to complete the assembly drawing and the drawings of the main parts.

3. 研究计划与安排

1-2 (19^th ,20^th weeks of semester 7) chose the topic of graduation design, graduation design task book (parameters), the data collection

3 (1^st week of semester 8 ) schematic design, literature retrieval, complete proposal.

(2^nd ,3^rd weeks of semester 8) internship, external data collection, complete the internship report

4. 参考文献（12篇以上）

[1] poria fajri, sangin lee, venkata anand, kishore prabhala, mehdi ferdowsi. modeling and integration of electric vehicle regenerative and friction braking for motor/dynamometer test bench emulation [j]. ieee transactions on vehicular technology, 2016,61 (10): 5798-5808.

[2] zhang qi, fu xiaoling, li ke, xing guojing, zhang chenghui. the pure electric vehicle power system and optimal braking strategy [j]. journal of system simulation,2016,(3):600-609.