Automotive Transmission

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Automotive Transmission
The role of transmission  
The output of the engine speed is very high, maximum power and maximum torque at a certain speed area. Engine in order to exert the best performance, it is necessary to have a variable-speed devices, to coordinate the engine speed and the actual wheel speed. Transmission process in the car, in between the engine and the wheels have a different gear ratio, by shifting the engine can work at their best performance of state power. Transmissions are the development trend of more and more complex, increasingly high degree of automation, automatic transmission will be the mainstream of the future.  
Transmission type  
Automotive automatic transmission has three common forms: namely, Automatic Transmission (AT), mechanical stepless automatic transmission (CVT), electric-controlled mechanical automatic transmission (AMT). At present, the most widely used is the AT, AT almost become synonymous with automatic transmission.  
AT Torque by Torque, and planetary gear and hydraulic control system components, through the hydraulic transmission and gear portfolio approach to achieve variable-speed torque variation. One of Hydraulic Torque is the most important parts, which pump wheels, turbines and components, such as guide pulley of the transmission of both torque and the role of clutch.  
AT compared with, CVT save the complex and cumbersome combination of variable-speed gear transmission, but the two groups to carry out variable-speed drive pulley. By changing the driving wheel and driven wheel contact belt speed radius. Canceled because of gear, so the transmission ratio can change speed more smoothly, without shifting sense of the sudden jump.  
AMT and Automatic Transmission (AT) are the same class has automatic transmission. It is in general based on the manual transmission, through the installation of microcomputer-controlled electric device to replace the original finish by the manual operation of the clutch of separation, joint, and block transmission of the election, motion shift, automatic shift implementation.  
The general structure of automobile transmission  
1. Easy transmission of the basic structure: the shell, transmission and manipulation of some parts.  
(1) Shell: Shell is the basic pieces of support for the installation of transmission and storage of all parts lubricants. Has installed its bearing on the precision boring. Transmission under varying load, so the stiffness of the shell should be enough, there is to strengthen the wall, the shape of the complex, as many castings (gray cast iron materials, commonly used HT200).  
In order to facilitate the installation, transmission and manipulation of some Split parts are frequently made, cover with the housing connected by bolts and reliable positioning. Shell has come on up, I put the oil, check oil foot mouth, should also be taken into heat dissipation.  
(2) Transmission parts: is the gear, shaft, bearings and other transmission parts. Geometry axis through strength, stiffness calculation. Mainly due to decide on the stiffness, while the carbon steel and alloy steel elastic modulus almost equal, so the general use of carbon steel (commonly used 45 steel). Only one gear with the shaft or axle load made serious only by steel. Shaft and gear for many spline connection (for neutral good, reliable transmission of power, a small compressive stress, etc.). Spline shaft bearing parts and let the surface hardening treatment by the Department. Shaft with rolling bearing supports many, easy lubrication, high efficiency, small radial clearance, axial positioning should be reliable. Many ways to use splash lubrication (υ> 25m / s, as long as the appropriate viscosity apparently succumbed to the wall).  
(3) to manipulate parts: the main components located inside the transmission cover.  
2. The composition of the structural characteristics of transmission: there is easy and efficient transmission, the advantages of simple easy-to-use-Jun mine but a few files, i changed the scope of small (traction, speed small), file number should be taken only at certain limited Cut used. If the increase in the scope of i, then increase the size so that transmission, axle span increase, both in order to increase the file-axis span of a few do not make too large, transmission can be formed. The composition of the so-called transmission, usually from both a combination of easy transmission, one of a few more files as the main transmission, less transmission known as the deputy.  
Transmission component of advantages:  
(1) can reduce the number of gears, and a few more files to reduce the number of gear the more obvious advantages. Easy compared with the transmission, it can shorten the length of shaft to reduce the transmission of the external size and weight, and can easily be more than one reverse. Into the file so the current number of files more than six hours, almost all transmission components.  
(2) transmission: the rate of change of Ω than large: if the main transmission gear ratio change rate Ωzu = 3, Vice transmission Ωfu = 4 is Ω = 12; easy transmission arrangement Ω = 12, the structure is often difficult to reasonable.  
Composed of transmission of disadvantage:  
(1) file groups have correspondence between the transmission ratio, so that each file is not 2, (the speed and traction) are ideal.  
(2) manipulation of trouble shifting, and sometimes both want to manipulate some speed, if not for the flower arrangement will shift memory.  
In order to reduce the control action, it is best to shift the order. Calling attention to the grade for this presentation ten out files so that the first group of transmission ratio is greater than all of the first file group 11 to the majority of phase transformation from the stall speed of just fixing the main purpose of this is the only way most convenient.

GM Hydra-Matic  
General can be regarded as the founder of automotive automatic transmission has been. The world's first automatic transmission is used in the United States in 1940 Oldsmobile automobile on a common, and it is a tandem structure of planetary gear transmission fluid control. Applies to the Cadillac STS-V's latest six-speed Hydra-Matic automatic transmission 6L80, may be regarded as the world's most advanced Automatic Transmission (AT) has been.  
Automatic Transmission For example, it has an internal gear is also divided, but the abolition of the clutch. The more gear, then shift, the better the ride comfort. At present, common automatic transmission are generally four-speed, that is, block has four forward. 6L80 has six forward gear, the number of teeth than the one block are separately 2.36,3 block 4.03,2 block 0.85,6 block 1.15,5 block 1.53,4 block 0.67. Obviously, it is more than 4-speed automatic transmission with a greater ratio and smaller ratio of the difference, it is more smooth when speed.  
Outside the block a few more besides, 6L80 also has a lot of unique special skills:  
Driver shift control system (DSC) - through its driver into a vehicle without the clutch from the automatic five-speed, high-performance手动挡. Drivers under the food stalls to the DSC on the location, the light touch can be specified at the scope of the neat, smooth implementation block addition and subtraction. The driver to switch control mode, the transmission control module monitors the vehicle speed, engine torque and gear used to decide whether to automatically add block to avoid damage to the powertrain. Each have a sliding gear on the clutch, can be carried out on all five gear engine braking.  
Performance computing systems down block (PAL) - in a row after a high-speed, stop升挡maintain engine braking. Transmission control module based on driving behavior to decide whether to activate the device. If the system found in the vehicle slowed down before turning, transmission may be even lower in order to avoid stall two block.  
Performance computing shift system (PAS) - turn off the accelerator in high-speed automatic adjustment of the level of acceleration gear, re-open at throttle-down power to elevate. Once the transmission control module to detect high levels of command, this function immediately.  
This transmission also reduced in the rugged mountain road "Shift Search," the stability of the shift functions, with the lower block BrakeAssist monitoring function, electronically controlled engine braking, as well as to adapt to these high-power, high torque engines are the new need a new dual-chip torque converter. In addition, SRX is also equipped with high-performance downhill Downgrade Detection Brake Assist.   Chinese car market gearbox  
China's auto market is in a transmission period of rapid development. 2007 Chinese sales of 8,791,500 motor vehicles, motor vehicle production in 2008 will exceed nine million sales, car sales in 2010 will reach 12.63 million. Size of the market in the automotive industry's rapid growth, China is faced with a major transmission industry opportunities. In 2006 the market scale of China's automobile transmission up to 300 billion yuan and more than 20% annual growth is expected in 2010 is expected to reach 60 billion yuan.