Transmission: 8-speed CVT automatic manual transmission?

CVT technology has once again become one of the new technologies that people pay attention to. Here is a brief introduction to the principle of CVT, so that everyone can know the difference between CVT technology and manual transmission and automatic transmission which are widely used now. \x0d\ AT present, there are manual gearboxes (MT), automatic gearboxes (AT) and continuously variable gearboxes (CVT) on the market. \x0d\ 1, mt: \ x0d \ manual gearbox (mt: manual gearbox) adopts gear set. Because the number of teeth in the gear set of each gear is fixed, the speed ratio of each gear is a fixed value (so-called "gear"). For example, the first gear ratio is 3.455, the second gear ratio is 2.056 and then the fifth gear ratio is 0.85. Multiplying these numbers by the main reduction ratio is the total transmission ratio. The total transmission ratio has only five values (that is, there are five gears), so it is a gear shift. \x0d\ Manual transmission is the most common transmission, and its basic structure can be summarized in one sentence, that is, two shafts and an intermediate shaft, namely, the input shaft, the output shaft and the intermediate shaft, which constitute the main body of the transmission, and of course, the reverse shaft. Manual transmission, also known as manual gear transmission, contains gears that can slide in the axial direction. Through the meshing of different gears, the purpose of speed change and torsion is achieved. \x0d\ 2. AT: \ x0d \ Automatic transmission (AT: automatic transmission) uses the vehicle speed and load (the stroke of the accelerator pedal) for two-parameter control, and the gear automatically shifts up and down according to the above two parameters. The similarity between at and MT is that they are both stepped transmissions, but AT can automatically increase or decrease the gear according to the vehicle speed, which can eliminate the "frustration" of the hand gear. \ x0d \ (1) Structure of AT: \ x0d \ Compared with manual wave, hydraulic automatic wave (AT) is quite different in structure and use. Manual wave is mainly composed of gears and shafts, which produce speed change and torque through different gear combinations; AT is composed of hydraulic torque converter, planetary gear and hydraulic control system, which realizes speed change and torque change through hydraulic transmission and gear combination. Among them, hydraulic torque converter is the most distinctive part of AT, which is composed of pump wheel, turbine and guide wheel, and directly inputs engine power to transmit torque and clutch action. \ x0d \ (2) Advantages and disadvantages of AT: \x0d\ AT does not need a clutch to shift gears, and the gear position changes slightly and greatly, and the connection is stable and the operation is simple, which brings convenience to drivers and comfort to passengers. \x0d\ but there are many shortcomings. First, it is slow to respond to speed changes and is not sensitive to manual gears, so many riders like to drive manual gears; Second, the fuel consumption is uneconomical, the transmission efficiency is low and the torque range is limited. In recent years, the introduction of electronic control technology has improved this problem; Third, the mechanism is complex and it is difficult to repair. The high-speed circulating hydraulic oil in the torque converter will produce high temperature, so the specified high-temperature resistant hydraulic oil should be used. In addition, if the car cannot be started due to insufficient battery power, it cannot be started by a cart or trailer. If the faulty vehicle is towed away, the driving wheel must be off the ground to protect the automatic wave gear from damage. \x0d\ (3)AMT\x0d\ AMT is modified on the basis of the original mechanical transmission (manual wave), mainly changing the manual shift control part. That is, under the condition that the overall transmission structure is unchanged, the automation of gear shifting is realized by adding an automatic control system controlled by a microcomputer. So AMT is actually a robot system to complete the clutch operation and gear selection. Because AMT can be modified on the basis of manual wave in production, it has good production inheritance and low investment responsibility, and is easily accepted by manufacturers. The core technology of AMT is microcomputer control, and the electronic technology and quality will directly determine the performance and operation quality of AMT. \x0d\ 3, CVT:\ x0d \ CVT (continuously variable transmission) differs from a continuously variable transmission in that its transmission ratio is not a discontinuous point, but a series of continuous values, for example, it can be changed from 3.455 to 0.85. CVT is simpler in structure and smaller in size than traditional transmission. It has neither numerous gear pairs of manual transmission nor complex planetary gear sets of automatic transmission. It mainly depends on the driving wheel, driven wheel and metal belt to realize the stepless change of speed ratio. \x0d\ Its principle is that several groups of gears with different sizes, like ordinary gearboxes, are divided and combined under control to form different speed ratios, just like the pedals of bicycles drive wheels to rotate at different speeds through large and small wheels and chains. Because different forces have different thrust on each group of gears, the output speed of the gearbox changes accordingly, thus realizing slow rotation regardless of grades. \x0d\ CVT uses a transmission belt and a ratchet wheel with variable groove width to transmit power, that is, when the ratchet wheel changes the groove width, the contact radius between the driving wheel and the driven wheel also changes, and the transmission belt generally adopts rubber belt, metal belt and metal chain. CVT is truly stepless speed change. Its advantages are light weight, small volume and few parts. Compared with AT, CVT has higher working efficiency and lower fuel consumption. However, the disadvantage of CVT is also obvious, that is, the transmission belt is easy to be damaged and cannot bear a large load. It can only be used in low-power and low-torque vehicles with a displacement of about 1 liter, so the automatic gear occupancy rate is below 4%. In recent years, the situation has improved after vigorous research by major automobile companies. CVT will be the development direction of automatic gearbox. \x0d\ At present, there are three CVT products in China, namely Audi, Fit and Siena, and the fourth CVT listed is Yun Qi. Among these four products, only Audi and Yun Qi have cruise fixed speed. \ x0d \ History of CVT \ x0d \ The development of CVT technology has a history of more than one hundred years. German Mercedes-Benz Company is the originator of adopting CVT technology in automobiles. As early as 1886, the V-type rubber belt CVT was installed on the gasoline engine produced by the company. 1958, Dr. H.Van Doorne of Dutch DAF company successfully developed a double V-shaped rubber belt CVT named Variomatic, which was installed on Narcissus cars manufactured by DAF company, and the sales volume exceeded 1 10,000 vehicles. However, the rubber belt CVT has a series of defects, such as limited power (torque is limited below 135Nm), unstable clutch operation, large energy loss of hydraulic pump, transmission belt and clamping mechanism, so it has not been generally accepted by the automobile industry. \x0d\ However, the research on improving the performance of transmission belt and CVT transmission power limit has been going on. Hydraulic torque converter is integrated in CVT system, and the clamping force of driving wheel and driven wheel is controlled electronically. CVT adopts energy-saving pump, and the traditional rubber belt is replaced by metal belt for transmission belt. The new technical progress overcomes the original technical defects of CVT system, which leads to the emergence of the second generation CVT with greater torque transmission capacity and better performance. Since 1990s, more and more attention has been paid to the research and development of CVT technology, especially in mini-cars, and CVT is considered as the key technology. With the rapid development of global science and technology, new electronic technology and automatic control technology are constantly being adopted in CVT. \ x0d \1In the first half of 1997, Nissan Company of Japan developed CVT for 2.0L cars. On this basis, Nissan developed 1998 CVT with manual shift mode for medium-sized vehicles. The new CVT adopts the newly developed high-strength wide steel belt and high hydraulic control system. By adopting these advanced technologies to obtain greater torque capacity, Nissan has researched and developed the electronic control technology of CVT. The change of transmission ratio is controlled by full-speed electronic control. When the car goes downhill, the engine braking can always be controlled according to the speed, and the speed ratio can be steadily increased on the wet road surface to prevent slipping. Nissan plans to expand the application scope of its CVT from 1.0 L to 3.0L cars. \x0d\ Mitsubishi Corporation of Japan chose CVT to transmit the power of direct injection engine smoothly without energy loss to drive the car. V-belt/transmission wheel mechanism can ensure the smooth and uninterrupted transmission of engine power at various speeds. CVT eradicates the tooth-beating phenomenon of traditional automatic transmission when shifting gears, thus obtaining more satisfactory response and control. Mitsubishi is going to adopt the combination of direct injection engine (1.5L or less) and CVT. \x0d\ Fuji Heavy Industries of Japan also has 15 years experience in developing CVT. 1In May, 1997, Fuji Heavy Industries assembled a fully computer-controlled E-CVT (CVT with six-speed manual shift mode) for its Vistro mini-car. The driver can make a six-speed shift without operating the clutch. Fuji Heavy Industries adopted an electronically controlled CVT with a locking torque converter on the Pleo mini-car. The slip of the torque converter can be kept to a minimum through a small range of locking, and the planetary gears are used to switch forward/reverse gears. The transmission ratio range is1:10-5.5:1. \ x0d \1In the first half of 1999, Ford of the United States and ZF of Germany cooperated to produce CVT for Ford cars and light trucks. The new joint venture between Batavia and Ohio will start producing CFT23 CVT with electronic management function designed for Ford from 200 1. CVT designed by ZF Company is a kind of torque converter transmission, which uses steel belts produced for installing front-wheel drive cars with transverse engines. ZF can also produce CVT series longitudinal engines for front-wheel drive vehicles and rear-wheel drive vehicles. ZF said: Compared with four-speed automatic transmission, CVT system can improve acceleration performance 10% and fuel economy 10%- 15%. Compared with lock-up torque converter, CVT system is more efficient and will not leak oil. Ford is designing a traction drive CVT to match all the company's light trucks, including rear-wheel drive and all-wheel drive trucks. Traction drive uses a slider that moves along a special sliding fluid to replace the drive belt and drive wheel. The relative position of the sliding parts determines the transmission ratio, and the power is transmitted through a thin layer of liquid oil between parts. \x0d\ German ZF Company began to provide steel belt drive VT 1 CVT for Rover 2 16 cars in the middle of 199. The CVT includes spiral gear or transmission device, suitable hydraulic system and wet clutch. The ECU integrated in the system can further combine mechanical, hydraulic and electronic systems, so as to make better use of the unique advantages of various systems. \x0d\ The electronic CVT control system of Bosch in Germany is based on the electronic/hydraulic module controlled by sensors and actuator units. Bosch integrates independent components, actuators, sensors and transmission shift ECU into a module, and transmission manufacturers only need to add an integrated control unit. \ x0d \ Application of CVT transmission \x0d\ 1987. Subaru of Japan put the CVT transmission on the market and achieved success. Ford and Fiat in Europe are also equipped with VDT-CVT on cars with displacement from 1. 1L to1.6L. With the development of technology, the global awareness of energy conservation and environmental protection has been enhanced by the energy crisis. Based on the experience of the first generation CVT, a CVT with better performance and greater torque capacity is developed. At present, in order to improve the competitiveness of products, the world's major automobile manufacturers are vigorously developing CVT. Now Nissan, Toyota, Ford, GM, Audi and other famous automobile brands are selling cars equipped with CVT transmissions, and the annual output of CVT cars worldwide has reached nearly 500,000. It is worth noting that the automobile market equipped with CVT first penetrated into the North American market from Japan and Europe, so CVT is the main trend of automobile development today. \x0d\ China has a huge automobile sales market, and the automobile industry is one of our national industries. The automatic transmission (AT) needed by China's automobile industry is imported, which greatly increases the cost of domestic cars equipped with AT, while the cost of CVT transmission developed and produced by the equipment itself does not increase much, indicating that the market prospect of CVT is promising. \x0d\ At present, China is considering developing automatic transmission for automobiles. Since the "Ninth Five-Year Plan", the research and development of metal V-belt CVT for automobiles has been included in the national major scientific and technological research plan, in order to track the technological development of the world and develop automobiles suitable for China's national conditions. \x0d\ In the last decade, CVT technology has taken a big step forward, making CVT more competitive than mechanical transmission MT with a history of 100 years and automatic transmission AT with a history of more than 50 years. CVT technology is at the beginning of its life cycle, and the characteristics of CVT will be further improved. What is \ x0d \ What? The main structure and working principle of \x0d\ CVT are shown in figure 1. The system mainly includes driving wheel set, driven wheel set, metal belt and hydraulic pump. \x0d\ Structural diagram of electronic control system of continuously variable transmission \x0d\ Metal belt consists of two metal rings and hundreds of metal sheets. Both the driving wheel set and the driven wheel set are composed of a moving disk and a fixed disk. The pulley on one side near the oil cylinder can slide on the shaft, while the pulley on the other side is fixed. Both the moving disk and the fixed disk are conical structures, and the conical surfaces form V-shaped grooves to mesh with the V-shaped metal transmission belt. The power output by the engine output shaft is first transmitted to the driving wheel of CVT, then transmitted to the driven wheel through V belt, and finally transmitted to the wheel through reducer and differential to drive the car. When working, the movable discs of the driving wheel and the driven wheel move axially, changing the working radius of the engagement between the conical surfaces of the driving wheel and the driven wheel and the V-shaped transmission belt, thus changing the transmission ratio. The axial movement of the moving disk is realized by the driver adjusting the hydraulic pump cylinder pressure of the driving wheel and the driven wheel through the control system as needed. Because the working radius of the driving wheel and the driven wheel can be continuously adjusted, stepless speed change is realized. \x0d\ In the hydraulic system of metal belt continuously variable transmission, the role of the slave cylinder is to control the tension of the metal belt to ensure efficient and reliable transmission of power from the engine. The driving cylinder controls the position of the driving cone wheel to move along the axial direction, and the metal belt moves along the V-shaped groove in the driving wheel group. Because the length of the metal belt is constant, the metal belt changes in the opposite direction along the V-shaped groove in the driven wheel set. The radius of gyration of the metal belt on the driving wheel set and the driven wheel set changes to realize the continuous change of speed ratio. \x0d\ auto start, the working radius of the driving wheel is smaller, and the transmission can obtain a larger transmission ratio, thus ensuring that the drive axle can have enough torque and the automobile can have a higher acceleration. With the increase of vehicle speed, the working radius of driving wheel decreases gradually, the working radius of driven wheel increases correspondingly, and the transmission ratio of CVT decreases, so that the car can travel at a higher speed. \x0d\ CVT features \x0d\ 1 and economy \x0d\ CVT can realize a wide range of stepless speed change, thus obtaining the best matching between the transmission system and the engine working conditions and improving the fuel economy of the whole vehicle. German Volkswagen installed 4-AT and CVT on its golf VR6 car for ECE urban cycle and ECE suburban cycle test, which proved that CVT can effectively save fuel (see table 1) \x0d\ Volkswagen's golf VR6 car and 4-AT and CVT \x0d\ Test fuel consumption 4-AT CVT \ ECE urban cycle, L/100km14.413.2 \ x0d \ comparison 120km/h, l/100km10.39.2 \ x0d. The greater the reserve power of the car, the better the power of the car. Because of CVT's stepless speed change characteristics, the transmission ratio of maximum reserve power can be obtained, so the dynamic performance of CVT is obviously superior to that of mechanical transmission (MT) and automatic transmission (at). \x0d\ 3, emission \x0d\ CVT has a wide working range of speed ratio, which can make the engine work in the best working condition, thus improving the combustion process and reducing exhaust emissions. ZF Company has tested its own CVT, and the exhaust emission is about 10% lower than that of the vehicle equipped with 4-AT. \x0d\ 4. Cost \x0d\ CVT system has a simple structure, and the number of parts is less than AT (about 500) (about 300). Once automobile manufacturers start mass production, the cost of CVT will be lower than that of AT. Because the system can save fuel, with the mass production and the innovation of system and materials, the production cost of CVT parts (such as transmission belt or chain, driving wheel, driven wheel, hydraulic pump, etc.) will be reduced by 20%-30%. \x0d\ There is no doubt that the technical content and manufacturing difficulty of CVT transmission are higher than that of MT transmission and similar to that of at transmission. Because of its simple structure, metal belt CVT contains about 40% less parts than at transmission, and the quality of the whole vehicle is also reduced. \x0d\ 5。 Ride Comfort \x0d\ Because the speed ratio of CVT is continuously changing, the acceleration or deceleration process of the car is very gentle, and driving is very simple and safe. Let users get all-round "driving pleasure". CVT also refers to Intel Clear Video Technology \ x0d \ Intel Clear Video Acceleration Technology \x0d\ G965 GMA X3000. As the core of Intel's fourth generation drawings, its specifications have been further improved. Become the first Intel IGP chipset supporting Direct X 9.0, Sharder Model 3.0 and OpenGL 1.5, with the computing power of hardware Pixel Sader 3.0 and vertex shader 3.0, and hardware Transform &；; Lighting (T & ampl) and full-precision floating-point operation support HDR effect, its strength can never be ignored, and it can enjoy up to 256MB of system memory. \x0d\ Intel has designed its own 2D image acceleration technology on GMA X3000, Intel Clear Video Technology, which can use a brand-new display core and adopt more advanced algorithms to enhance the playback of high-definition images and improve the image quality and color jitter during video playback. And enhance the advanced display capability (HDMI) on PCs and home appliances, which can be completely in line with nVIDIA's pure video and ATi's Avivo. The clear video technology focuses on the advanced de-interlacing algorithm, and with the ProcAmp color control settings, the picture quality will be better and the performance will be improved when playing high-definition video content such as MPEG2-2 and WMV, and multiple video streams corresponding to 1 HD and 1 SD streams can also be played simultaneously. In terms of output interface, Intel Clear Video Technology can support popular HDMI video and audio interfaces, which makes it easy for the G965 motherboard to connect HDTV and computer monitors. \x0d\ Generally speaking, compared with NVIDIA PureVideo and ATi avivo 2D video processing engines, Intel Clear Video Techmology has some shortcomings in the supported video formats, such as H.264 format, which is more optimistic now. Of course, we are not sure whether the H.264 decoder will be added through the driver in the future. Fortunately, Intel has added the support of HDMI interface, which makes G965, as a low-cost HTPC, better connected with future home appliances. [1][2][ Edit this paragraph] Overview of ]CVT-Capacitive Voltage Transformer 1 \x0d\ Capacitive Voltage Transformer (CVT) has a development history of more than 40 years abroad and has been widely used in 72.5 ~ 800 kV power systems. Since 1964 was born in Xi 'an Power Capacitor Factory, domestic CVT has accumulated 35 years of experience in manufacturing and operation, and has now entered a mature stage. Especially in recent years, domestic CVT has made a breakthrough in improving accuracy and output capacity, and successfully adopted fast saturated reactance damper, which obviously improved the ferromagnetic resonance damping characteristics and transient response characteristics. Domestic CVT has reached or exceeded the performance index of electromagnetic voltage transformer (VT), and has the advantages of high insulation strength, no ferromagnetic resonance with the system, low price at high voltage, and can be used as the coupling capacitor of carrier communication (PLC), which has been widely recognized by users in power sector. Therefore, since the Ninth Five-Year Plan, domestic CVT has been widely used, and the product voltage range covers 35 ~ 500 kV. In 1 10 ~ 220 kV, the quantity of CVT has occupied an absolute advantage. CVT is often used instead of VT not only in new stations, but also in the transformation of old stations, and CVT is selected for 330 ~ 500 kV grades without exception. Even at 35 ~ 66 kV, the price of CVT is not dominant. Considering the fundamental elimination of ferromagnetic resonance between VT and the system, some power stations also choose CVT. Since 1995, the production and sales volume of CVT has increased by 25% annually, reaching 4,700 units in 1998, accounting for 90% of voltage transformers of10kV and above. During this period, with the development of power capacitor insulation technology and material science, the design and manufacturing technology of CVT abroad has made great progress, and some new products have appeared. We should summarize the experience of CVT manufacturing and operation at home and abroad in time, further promote the development of domestic CVT, and provide high-quality and reliable products for the construction and transformation of urban and rural power grids and the construction of EHV power grids in China.