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1=SimSun first proposes two conditions and various types of continuously variable transmission methods that must be met to achieve infinitely variable speed, and introduces the existing type of continuously variable transmission as the main line, and from the development process of various types of continuously variable transmissions. Looking forward to the future development trend.
1 Infinitely variable transmission type The two technical problems that need to be solved are the continuous change of the speed and the stable operation at any transmission position.
To meet these two requirements, there are a variety of transmission modes 4 that utilize flexible medium transmission, such as hydraulic transmission using liquid as the transmission medium. The transmission mode is a combined transmission mode, and a hydraulic torque converter or a hydraulic coupler filled with a liquid is placed between the engine and the gearbox, and the torque of the liquid can be used to make the torque converter or the fluid coupling. The gear ratio varies within a fixed range and, in combination with a stepped gearbox, achieves a range of continuously variable transmissions. 6 The transmission with electromagnetic flow as the medium, this kind of shifting mode is mainly based on motor speed regulation, and has electromagnetic slip type DC motor type and AC motor type. In the friction transmission, the contact position between the main and the driven parts can be easily changed. With this feature, the transmission ratio can be continuously changed, so the friction type continuously variable transmission is the most widely used type of transmission. . 4 pulsating stepless speed change, pulsating type stepless speed change is a combination of way to achieve stepless speed change, with the link mechanism as the main body, the one-way overrunning clutch is the speed filter device, filtering out the speed within a certain range, outside the range The rotational speed will not be output, and since this output rotational speed is pulsating, it is called a pulsating continuously variable transmission.
2 Different implementations of the continuously variable transmission will enable the research of the transmission to move forward in different directions. The transmission of flexible liquid or electromagnetic flow as a medium has led to the development of infinitely variable speeds in the direction of control. The realization of hydraulic continuously variable transmission is a torque converter or a fluid coupling, which is usually combined with a gear transmission. The gearbox is a stepped transmission, and the torque converter or coupler can realize stepless change of the speed, thus achieving stepless transmission. This type of transmission requires consideration of the transmission characteristics of the torque converter or coupler and the coordinated control between the torque converter or the coupler and the gearbox. Essentially, the torque converter is used to control the gearbox. . The continuously variable transmission with the electromagnetic flow as the medium is usually called the electric power stepless speed regulation transmission, and can be divided into the DC transmission and the AC transmission. This stepless speed change method involves the field of motor control, and the speed regulation performance depends on the motor speed control and control level.
The mechanical continuously variable transmission is called a mechanical continuously variable transmission by a mechanism or a purely mechanical component. The current transmission forms mainly include friction type and pulsation type. In the basic theory of mechanical design, the basic forms of mechanical transmission are friction transmission gear transmission belt drive chain transmission and mechanism transmission. The transmission mode of the friction type continuously variable transmission is a combination of these basic transmission modes, and the pulsating continuously variable transmission is a combination of mechanisms.
3.1 Friction type continuously variable transmission and its development process Friction type is the simplest and most easy to realize stepless speed change transmission mode. The design of the continuously variable transmission is started from friction type. The flat plate type of the roller is the simplest type of structure. The roller is the active part, the flat plate is the driven part, and the roller relies on the friction between the roller and the flat plate to drive the flat disk to rotate, and the contact position of the roller and the flat plate can be adjusted at will. The drive radius is also changed accordingly, and the angular velocity of the disc changes. The continuously variable transmission has a simple structure and is easy to implement, and the contact area between the roller and the disk is small, the contact stress at the contact is large, and the shift range is small due to the limitation of the structural size. Therefore, the designer has proposed a new structure, the cone-and-ring disc type stepless transmission, the principle is the same as the former, but the contact area is increased, so the transmission power is also increased accordingly, and then the above-mentioned several in the cone-ring disc type. All types of continuously variable transmissions are direct contact between the main followers, relying on the friction between each other to transmit power, without the use of intermediate rolling bodies, and then the use of intermediate rolling elements between the main driven elements The continuously variable transmission is called an intermediate component type continuously variable transmission. The emergence of intermediate components has provided space for the expansion of the CVT, and the design of the CVT has entered a new phase.
The steel ball flat plate type is the original form, the steel ball outer cone type and the steel ball inner cone single roller cone flat plate type roller cone flat plate type, etc. The final rolling element and transmission parts ratio, the appearance of the intermediate components opens up a design for the design. For a vast space. Although the intermediate element or the transmission element can have a variety of shapes, the transmission form does not change, but is a simple form of friction transmission. In view of the planetary gear transmission, the planetary gear with the cone and the ring as the sun gear and the middle rolling element as the planetary gear, the planetary transmission has undoubtedly taken a big step forward in the composition of the mechanism, and its transmission range has large output characteristics. The high load carrying capacity and the compact structure of the pressing device and the operating mechanism are relatively simple.
The continuously variable transmission evolved from the basic mechanical transmission mode also has a belt type and chain type continuously variable transmission. The difference from the ordinary transmission mode is the chain single, the speed regulation is convenient, and the appearance of the metal belt solves the low life of the rubber belt and the transmission power is small. The defects are widely used in automobiles, especially limousines.
3.2 Non-friction type continuously variable transmission Pulsating type stepless speed change is a kind of mechanical stepless speed change mode other than friction type. Its implementation is a bit like the pole-to-AC phase in the circuit, and the stepless speed change mechanism is composed of at least one phase. By the filtering action of the overrunning clutch, the speed lower than a certain speed value is filtered out, and the output speed corresponding to the one-way clutch filtering condition is output. Since the speed fluctuation of the transmission mode is relatively large, it is called a pulsation type.
Research Status of Continuously Variable Transmission At present, the research on continuously variable transmission mainly follows the following steps: hydraulic stepless speed change, motor speed regulation and mechanical stepless speed change. From the field of research and development, hydraulic and motor speed regulation can be regarded as the research on the control system. Its development field is relatively small compared with the mechanical continuously variable transmission, and the magneto-rheological fluid is related to the hydraulic transmission. The discussion of the principle of the continuously variable transmission indicates that although the intermediate medium adopts a special material, there is no qualitative change in the basic transmission form, and the motor speed limitation is also great. From the development history of mechanical continuously variable transmission, the friction type continuously variable transmission has undergone the direct transmission intermediate component type and has evolved the planetary continuously variable transmission. In this process, the CVT is used in each stage of development. The structure is simple to complex, and the contact surface between the transmission elements is developed from a simple contact mode to a more adaptable surface shape for improving the transmission characteristics, and the pressurizing and speed regulating devices are also being continuously improved. Later, with the improvement of mechanical materials and processing technology, belt and chain stepless speed change has also been widely used.
The forward friction and hydraulic continuously variable transmissions of the continuously variable transmission have defects such as low transmission efficiency and large power consumption, and cannot be driven with a precise transmission ratio. Friction type stepless speed change can not transmit high power and has large friction loss. The hydraulic stepless speed change can transmit a large amount of power, but it needs to pay for the transmission efficiency, low power consumption and high cost. Non-friction type continuously variable transmission has gradually become the future development direction of the continuously variable transmission.
Gear transmission is the most commonly used mechanical transmission method. It can be overcome in the infinitely variable speed, but it is difficult to overcome. The gear transmission can not achieve stepless speed change, which is the most common understanding. Gear transmission has the advantages of good reliability, smooth transmission and high transmission efficiency. For the various types of gear transmissions currently available, the transmission ratio is relatively fixed, and the stepless speed change cannot be realized. However, this does not mean that the gear has no distance with the stepless speed change. Changing the tooth shape to make it suitable for stepless speed change is the direction that people are pursuing. Some people have proposed the Archimedes spiral gear, and the tooth shape changes along the dimension to realize Infinitely variable speed. We can also boldly envisage the use of a non-conventional tooth profile on the conical surface. The arrangement of the tooth profile on the conical surface meets the following requirements. The determined transmission position can be transmitted with a stable gear ratio. The number of teeth along the conical axis The direction is increased, and the contact position between the two transmission elements can be changed along the direction of the conical axis during the transmission process, and the linear speed of the cone changes in the axial direction, thereby achieving stepless speed change. We can also design a kind of flexible gear. During the meshing process, the effective number of gears can be adjusted as needed, and the stepless speed can be realized. In terms of the organization, the combination of different types of institutions can also achieve infinitely variable speed. Chongqing University has proposed a new type of continuously variable transmission, which is based on the original pulsating continuously variable transmission. Although there is still a distance from the actual use, it can be a great breakthrough in the design of the mechanism.
Yan Zhongtang. Guide to design and selection of mechanical continuously variable transmissions. Beijing Chemical Industry Publishing Zhou Youqiang. Mechanical continuously variable transmission. Beijing Machinery Industry Press, 2001.
Peng Mingtao. The development status of automotive belt type continuously variable transmission. Journal of Chongqing Technology and Business University, Ma Huai Lin. Automotive belt type continuously variable transmission technology and development. Beijing Auto, 1998 Liu Guangquan. The principle of the gear continuously variable transmission. Automotive technology, 1996 preparation.
Gold, Li Weili, and so on. The principle of a magnetorheological fluid continuously variable transmission. Journal of Southwest China Normal University, 2001.
Feng Yunhua, Du Li, et al. Structural innovation and design of a non-friction continuous acting continuously variable transmission. Journal of Chongqing University, 2003126.
Received the deadline for 2005 to turn to page 72 3 conclusion macro command is the best choice for automatic modeling and automated user operation in 0 people. The use of macro commands will greatly improve the speed of modeling analysis and experiment optimization, and also master the command language programming of ADAMS, which will play a guiding role in parametric analysis and in-depth development of ADAMSVIEW. And this macro command also has a certain versatility, can create a space curve corresponding to any external data, and has a fixed answer to the engineering practice. Dai Daixun, Hao Tianjue, Duo Yingxian, and so on. Automatic weapon design programming 1. Beijing Guo 2 Li Jun, Jie Junwen, Yan Wenjie, and so on. Also touch the example tutorial river. Beijing Institute of Technology Press, 2002157163.
3 Development prospects of building water supply plastic pipes 1 The country's vigorous promotion of chemical building materials can provide an excellent opportunity for the development of plastic pipes. Chemical building materials are the emerging category of building materials after the steel wood cement. Building water supply plastics is a chemical building material promoted by the state. The introduction of national and local policy documents has accelerated the promotion of chemical building materials. Since June 1, 2000, in the new residential buildings, it is forbidden to use galvanized steel pipes as water supply pipes, and to promote the application, the introduction, the pipe and the plastic pipes.
According to the construction business nine plan and the 2010 long-term goal plan, in 20012010, the demand for indoor cold water pipes in residential buildings is about 3xl05kma. The demand for hot water pipes is about 105. The demand for hot and cold water for solar water heaters is about 21041. The demand for other types of building hot and cold water pipes is about 1053. In addition, more than 2,600 foreign-related hotels in China have more than 400,000 guest rooms and 210,000 hotels have entered the peak period of renovation and renovation, and will be upgraded. According to the calculation of relevant people, the amount of hot and cold water pipes in hotels and restaurants is about the same, and you calculate according to the above aspects. In 2010, in the field of engineering construction, the demand for building water supply pipelines was about 6,105. When the national demand for residential buildings was eliminated, the galvanized steel pipes were promoted, and the plastic pipes of people, pipes, pipe-shaped pipes and other plastic pipes were used. The market potential of the tube is enormous.
1 Yang Shiying. Engineering plastics manual. China Textile Press, 1994.
Received date 200503
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