1.Objective and Significance (Including the Analysis of the Research Status at Home and Abroad)

With the rapid growth of China's passenger car market, the domestic passenger car stock is huge. At the same time, in order to meet the requirements of low-end market and fully develop the product line, despite the prevailing market situation of auto-transmission models, the traditional manual-transmission products are still indispensable.

Therefore, the type of clutch that manual transmission should match must also be the traditional mechanical clutch. In addition, due to the rapid development of the information age, the dependence on electronic components will be increasingly high in the future. Under some special conditions, in order to ensure the normal operation of the car, when the electronic components cannot work properly, the mechanical mechanism is the last guarantee, which also shows the necessity of research on mechanical clutch.

Modern automobile industry has a worldwide, is the development of comprehensive industry, the competition is becoming more and more fierce. Since the first automobile factory was founded in 1953, China has had more than 130 automobile factories and more than 700 automobile modification factories. With the rapid development of China's national economy and the continuous improvement of people's living standards, new requirements have been put forward for the use of automobiles. Customers have increasingly high requirements for comfortable driving and comfort of cars. So cars need to adapt their clutches to the demands of increasingly demanding customers in order to stay relevant in a volatile market.

Clutch includes; electromagnetic clutch, friction clutch, magnetic powder clutch and hydraulic clutch. According to the number of driven plates, friction plate clutch can be divided into single plate clutch, double plate clutch and multi-plate wet clutch. In the early stage of clutch development, the conical friction clutch is widely used, Its ability of transmitting torque is stronger than that of friction clutch with different structures of the same diameter, but its shortcomings are also obvious, and its operation is more complex, which requires driver's with certain driving experience and skills. Because of the large moment of inertia of the transmission part of the conical friction clutch, it is difficult to shift gears, and the combination is not soft enough, so it is easy to get stuck. Consequently, the conical friction clutch was gradually replaced by the wet multi-plate clutch. However, the multi-disc wet clutch also has some defects. The oil is easy to stick between the sheets in the clutch, which causes the clutch to be separated incompletely and causes difficulty in shifting gears. Therefore, it was gradually replaced by dry multi-plate clutch, which has many contact surfaces and can ensure a smooth start of the car. However, due to the large number of pieces, the inertia of the driven part is large, so the shift process is not very convenient and easy. The poor heat dissipation and ventilation effect of the middle pressure plate can easily lead to overheating, which accelerate the wear and tear of friction plate in the clutch, even burns and fractures, and affect the service life of the clutch. Moreover, if not adjusted properly, it may lead to incomplete separation of the clutch.

At present, most manual cars use diaphragm spring clutch as power transmission mechanism of automobiles.Diaphragm spring clutch is widely used in cars and light vehicles in recent years, its composition in generally includes: friction plate, torsional shock absorber, clutch control mechanism, driven plate assembly, clutch cover assembly separation bearing assembly, diaphragm spring. Its torque capacity is large and more stable, it is easy to operate, its balance is good, and it can be mass-produced. It is also very important for its research. Therefore, in order to optimize the design of the clutch, it is necessary to consider the optimal design of each basic component:

In the article "Design and Research of Jetway Clutch Diaphragm Spring" published in 2006, Hu Jing and others analyzed various factors affecting the characteristic curve of the diaphragm spring, and obtained a more reasonable correction coefficient, and proposed a correction formula that can be standardized production[1]; In addition, there are many design schemes for the optimization of the diaphragm spring. In the “Mechanical Analysis and Research on the Clutch Diaphragm Spring of Micro Cars”, Liu Anzhen from Wuhan University of Technology also proposed the optimization scheme by calculating the influence of lever ratio and the thickness of the diaphragm spring on the deformation characteristics of the clutch diaphragm spring load[12]. In the “Clutch Diaphragm Spring Optimization Design and Simulation”, Song Hongbin of Yanbian University optimizes the diaphragm spring and the friction plate[4]. The optimized diaphragm spring is in the wear range. The change of the compaction force is reduced, and the stability of the compression force is improved. In the "Optimal Design of the Automobile Clutch Diaphragm Spring" by Zhang Chao and Yuan Xiaolei of Chang'an University, the weighting coefficient is also introduced to adjust the two objective functions simultaneously, while the optimization of other components is relatively small[11]; such as Zhang Weibo of Fuzhou University in “The finite Element Design of the Clutch Pressure Plate Based on ANSYS”, based on the finite element analysis of the pressure plate, the stress distribution and deformation of the pressure plate under the thermal load are obtained[13]. According to the analysis results, the friction surface of the pressure plate is improved, it is concluded that the pressure plate design was reasonable.In addition to the components, the overall structural design and dynamic analysis are also essential. "Clutch Modeling Simulation Analysis" by Wang Dashuang of Wuhan University of Technology contains the building of a simplified three-dimensional model of the clutch as a whole, and then uses kinematics analysis software to simulate the motion process, including the analysis of the slip grinding stage, the surface temperature of the friction surface in the sliding stage, and the analysis of the sliding torque in the clutch engagement stage.After completion of the overall design, the calibration should undertake checking to ensure the normal use of the clutch[2]. “A New Car Clutch System Check” by Tao Faqiang and Zhang Ziyuan of SAIC General Motors Wuling Automobile Co., Limited provide the details of the clutch friction, backup coefficient, the temperature rise of the start, the clutch pedal force and the clutch pedal stroke as well as related design parameter checking method[9].

With reference to the design forms and the stable simulation and check method of the various schemes provided by each of the above predecessors, the design of the diaphragm spring clutch can be further developed and considered in many aspects.

Analysis of Research Status at Home and Abroad