CVT - a rapidly growing new type of transmission
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1=SimSun has introduced the Dingtech meter, which has been put into use, including metal belts and wheeled wheel roller chain wheel discharge. The article also analyzes the technical method of the Ding Transmission adopting the liquid knife torsion device, and the step-by-step speed change of the transmission. The planetary gear type automatic transmission has made great progress and development in recent decades. The installed rate of passenger cars and various construction machinery has become higher and higher, and the use of manual transmissions has been surpassed in developed countries. However, this kind of automatic transmission has many defects, including low transmission efficiency, high structural complexity, high cost, high crane and the inherent output characteristics of the engine cannot be fully matched. The automotive technicians insist on seeking a fuel-efficient economy and easy operation. A seamless CVT. Now this kind of transmission with continuously changing transmission ratio has appeared. It is the continuously variable transmission that starts to be used for loading. 0, D, 1 such as this 17 anus 31731 claws; 55; 0, D, the outstanding advantages are, can make the car realize The whole process of stepless speed change makes the maneuverability of the car produce qualitative progress, taking into account the economy and power of the car. It can match the gear ratio within the optimal speed range of the engine to achieve the smoothness under various working conditions; the transmission efficiency is stable. And up to 94,96, the speed ratio range of up to 5 can be compared with the speed ratio range of the manual transmission. Nowadays, people realize that the realization of Ding technology is called the manual technology from the manual transmission to the automatic transmission. The technology has already attracted widespread attention from the global automotive industry. At present, Europe and the United States have invested heavily in research and development, various forms of Ding technology and products have emerged one after another.
Practical Ding type Ding technology has been started to load, there are a variety of transmission methods to achieve stepless speed change, currently used in all types of cars, the main forms are, metal, type drive belt and movable pulley type, referred to as metal Belt, wheel, active turntable wheel driven turntable for introduction.
At the core of the metal belt and wheel technology is a metal drive belt with a very strong copper. It is coupled to a pulley that can be moved axially and has an adjustable width. The drive belt is pressed against a pulley with a variable radius. Form a mechanical continuously variable transmission. The driving radius of the pulley can be changed to change the main driven pulley metal driving belt by a combination of a high-strength flexible metal belt and a metal pushing block. The metal strip is made up of layers of soft molybdenum alloy strips, each strip is only 0.18 thick, and its tensile strength is extremely strong, but the flexibility is good; the push block is stacked on the flexible metal strip, and the dovetail type card is used. Installed, about 28, push the block above. Each block has a thickness of 2., a width of about 251 and a height of about 12, which is wedge-shaped; this steel push block has extremely high hardness and wear resistance, forming a drive steel strip 2 with a circumference of about 600,1, which can withstand High tensile and pressure 1 control system and electronic control system. In addition to the above-mentioned continuously variable shifting part, the mechanical shifting device also includes two single-row side-by-side and two-cylinder clutches, and two servo cylinders of the master-slave pulley; the hydraulic control system accepts computer commands, and the output oil pressure controls two clutch pressure servos. The cylinder has a total of cylinder movements to change the power transmission direction and the driving radius of the main driven pulley to achieve stepless speed change; in the electronic control system, the computer receives two signals of the engine throttle opening and the transmission output speed to determine the pulley width. The slip amount, the middle pulley position sensor is used as a feedback signal to detect the slip value that actually occurred in the pulley.
Intelligent 0 also automatically adjusts the line pressure of the hydraulic system based on the importance of the output torque. When the car starts or runs at medium and large loads, the transmission output torque M; h60M, the line pressure rises, the clamping force of the pulley to the drive belt increases, avoiding the slippage of the steel belt and ensuring the transmission of power by itself; When the transmission is running at medium and high speeds, the line pressure drops and the clamping force decreases, making the transmission work more smoothly.
The turret roller type uses a plurality of circular arc rollers to mesh with the inner arc-shaped turntables of two independent pairs of holes to transmit power. The basic principle of the slewing wheel type continuously variable transmission is that the technology of the children's toy is applied in the automobile shifting system. The car designer's thinking is broad and lively. The working principle of this structure is relatively simple. 3. The input turntable is rigidly connected with the crankshaft of the engine, and the output turntable is rigidly connected with the drive shaft. There are several pressing engaging rollers in the radial circumference 360 ​​between the input and output turntables. The roller can make a tilting swing at a fixed angle, and can change the meshing radius 7 with the wheel; and 7, can achieve different gear ratios. When 77, when it is decelerating motion, the output speed is lower than the engine speed; otherwise, when 77, it is the speed increase conversion.
The 殓 structure only relies on the hard metal friction between the roller and the two turntables, and it is impossible to transmit power at all. Just like the ball bearing, the rotation of the inner ring of the steel bowl cannot be driven by the balls to rotate the outer steel bowl. It is because the friction between them is too small. The real reason for this kind of slewing wheel type variable speed machine for power transmission is because there is a special kind of viscous oil that fills the entire inside of the transmission.
The flashing part of this viscous oil is a special long wedge shape. When the external pressure is low, the molecules are randomly arranged and the fluidity of the oil is good; but under the extremely high unit surface pressure, the molecules are forced to make rules. Parallel to the array, the macro is now producing huge shear stress. When the roller is pressed against the two turntables, the viscous oil under a high pressure, the oil film has a large shear stress, and the external traction is extremely strong, so that the meshed turntable rollers can transmit a large amount. Power, the transmission torque can reach 400, 1 with the transmission ratio can be. 2.5. This lays the foundation for the application of the turntable roller mechanism in the transmission of automotive power transmission.
The turntable roller type was actually used in the Nissan new male jazz 31 sedan. This concept car, which debuted in 1999, has attracted great attention from the automotive industry. The US and Japan car companies have been researching and developing. Mazda has also launched Ding, 1 such as the 1 type, and 1 in the 3 car. According to the measured data of Nissan, the sleek prospect of this turntable roller CVT is better than the traditional hydraulic planetary gears!
Chains, wheeled metal chains, wheeled continuously variable transmissions and metal belts, wheeled pulley widths to change the power transmission ratio, but the metal chain to replace the combined metal drive belt, making it a power transmission medium.
Such a continuously variable transmission also includes a mechanical shifting device and an electronic control system of the hydraulic control system. for. The energy loss between the metal chain and the belt pulley is prevented, and the pressing force between the chain and the wheel is adjusted according to the engine working condition and the transmission power requirement, and the pressing force is adjusted by the computer.
Chain, wheeled continuously variable transmission, for example, 1 has been installed on the 2.8 Audi 6 sedan and is planned to be exported to China. According to Audi, the use of chain 0 is less than the traditional Ding's 100-kilometer fuel consumption, and the 100-kilometer acceleration time saved 1.3 seconds. The 0, D, because of the high manufacturing precision requirements, the current price is more expensive, with the production of expensive production, the cost is expected to drop significantly, Ding's characteristics, the use of D-speed transmission will make the car superior to the manual transmission and planetary gear The dynamic transmission of the automatic transmission is comfortable and has a great increase in driving pleasure, and this is irrelevant to the proficiency of driving skills, so 1 will be acceptable. The main features of 0 ding are the following points: Electronic control 1 can achieve closed-loop control of engine power, the engine can run in the optimal speed range, so that the car gets good power. Using the stepless speed change electronic control 01, while maintaining the engine throttle and the speed is stable, the vehicle speed is adjusted by the transmission ratio of 0 butyl, and then the feedback closed loop control of the output speed signal can obtain the most engine and vehicle driving conditions. Good match. When the car accelerates the climb to increase the accelerator pedal, 0, D automatically increases the transmission ratio, and the engine can quickly achieve power to achieve power matching.
Low fuel consumption and good fuel economy. The 0-infinitely variable transmission can effectively coordinate the good matching between the driving load of the vehicle and the engine working condition. The engine works on the optimal fuel working line, and the fuel comparison test under the conditions of automobile use is improved. The result is clearly on the urban road. Dingbi 4 Ding fuel rate of 13,17! On the highway at a steady speed of 90, the fuel economy can still reach 6.
The engine's blowdown is reduced. As mentioned above, the closed-loop control of the engine power can be realized by using the D-system, so that the stable transmission ratio is wide, and the overspeed ratio of 5 can be obtained, so that the engine can obtain the torque output at a lower speed, and the transmission efficiency is higher. High engine combustion is fully stable. Tests show that with 0, D shifting system, COHC and NOx are greatly reduced in engine exhaust emissions, and the amplitude can reach 20.
Regarding the question of the development of Ding technology, whether the Ding transmission adopts a hydraulic torque converter has different technical treatment methods. For the metal drive belt, wheel type, Ding, the activity ratio is a minimum of 385, the maximum is 2.25, the transmission ratio is 5.8, the hydraulic torque converter can be no longer connected in series, and the electromagnetic clutch is connected in series between the engine and the Transfer and cut off the transmission of power. For the turntable roller type, the transmission ratio range is about 2.5, and it is better to connect a high-efficiency hydraulic torque converter to the main large torque value.
At present, the simulation of the Vybridge theory and the optimization design method have been used to design the torque converter cycle circle and the pump wheel turbine guide wheel, and the matching between the engine and the torque converter is optimized, so that the transmission efficiency is 90. Keep the gears asking. Ding is a stepless speed change technology, this can no longer set high, medium and low gear, but in order to meet people's driving habits and experience driving pleasure, especially the young people's rapid requirements for motor sports, so now the car is used, Ding transmission still Setting the virtual gear position mimics the manual transmission form, of course, this shifting operation is much simpler than the MT. 3CVT and integrated control of other systems in the car. Electronic control, Ding and engine can carry out effective closed-loop matching control, and can also be integrated with other electronic control systems. In fact, comprehensive intelligent control of multiple systems has been realized, which will improve the overall performance of the car.
China's research and development of 00 technology has begun. The Jilin University of Technology and the Power Transmission Research Institute of Jiaotong University have developed the Ding test device and conducted adaptive research tests. One of the tests is to use the strain gauge sensor to embed. Telemetry is transmitted through a clever antenna in a metal drive belt. Accurately measure a large amount of data on the tensile and lateral pressures experienced by the drive belt for research and development in China