1. 研究目的与意义（文献综述）

vehicle transmission is used to coordinate the engine speed and the actual speed of the wheel. it can change the engine output speed and torque to adapt to different working conditions in the process of driving, and make the engine work in the best state. therefore, the transmission is an important device of automobile. the performance of the transmission will affect the comfort, fuel economy and power performance of the whole vehicle. ^[1-3] with the development of automobile industry, transmission in china is in a period of high-speed development, and has occupied a dominant position in the field of mechanical transmission. but in the field of automatic transmission with higher level of design, manufacture and technology, our country is still in a backward period. at present, the proportion of automatic transmission used in high-end vehicles is as high as 90% in the world. the proportion of automatic transmission used in middle-grade and middle-grade vehicles is between 40% and 60%. at present, only 30% of passenger cars in china use transmission.

china's mechanical transmission product development capability is strong, assembly and parts development can be completed independently, in the field of traditional manual transmission independent enterprises have a great advantage. ^[4,5] in the field of automatic transmission in china, passenger automatic transmission is dominated by a few multinational companies. with the increasing demand for automatic transmission in the market, the core technology of automatic transmission is becoming increasingly serious. as far as the key technologies of ad, dct, amt and cvt automatic transmission products are concerned, our current situation is that the core technology of at is covered by patents of foreign companies. to bypass these patents, it requires not only high research and development costs but also high commercial risks to achieve technological breakthroughs by our own strength. dct's core technology is currently in the hands of two companies, luk and bogwarner of the united states. luk has no intention of joint venture with domestic enterprises, nor will it transfer related technology. the conditions of bogwarner joint venture are very harsh, requiring the ownership of the joint venture. ^[6-8] domestic amt is mostly used in heavy trucks, and the ecu control unit of single amt is trapped in the technical blockade of foreign enterprises. cvt technology is not blank in china. the road test of 30,000 km and the bench test of 200,000 km of cvt independently developed by private enterprises in china have been successful, but they can not be put into mass production because of their difficulties. ^[9,10] therefore, there is still a lot of room for transmission market in our country. i urgently need to develop automatic transmission technology. ^[11,12]

because of the late start of the research on automobile transmission in china and the immature technology, it is the only way to realize the dominant position of automatic transmission in the world in the future for china to continue the research on automobile transmission. this topic is aimed at the design, dynamic analysis and finite element analysis of automobile transmission. ^[13~15]

2. 研究的基本内容与方案

(1)basic contents of research (design)

1carefully consult the relevant information about transmission, understand the structure and working principle of various transmission, and compare the characteristics and advantages and disadvantages of various transmission.

2determine the research model, design a suitable transmission according to the parameters of the research model, and use the modeling software to establish the transmission model.

3. 研究计划与安排

1-2 (19-20 weeks of the 7th semester) to determine the topic of graduation design, improve the task book of graduation design (related parameters), and collect data in school

3 (8th semester, 1st week) project conception, literature search, completion of opening report

4-5 (2nd-3rd week of 8th semester) off-campus internship, off-campus data collection, foreign language translation and data re-collection

4. 参考文献（12篇以上）

[1] chen jiarui. fifth edition of automobile structure (volume 2) [m]. people's transportation press, 2006.

[2] wang wangyu. fourth edition of automobile design [m]. machinery industry press, 2007.

[3] yu zhisheng. fourth edition of automobile theory [m]. machinery industry press, 1981.