It is widely used nowadays, the transmission has been fully utilized, the answer is no, there is still a great potential, that is, can increase the number of transmission gear to increase the engine power utilization, increase the average vehicle speed. In order to increase the value in our country, but do not want to make the vehicle speed too low, you need to increase the power of the engine, but this is not an easy task, and to improve the transmission to a block, relatively speaking easier, in improving the engine power utilization At the same time, it also achieved the goal of improving the fuel economy of automobiles.
With a gearbox, the car speed is expressed in logarithmic coordinates. The zigzag clearance above this power characteristic diagram is greatly reduced, and the power utilization rate is greatly improved. At the same time, the maximum traction force is increased, which is conducive to the smoothness of starting on a steep slope or leaving the road. The structure and operation of the multi-speed transmission Regardless of the type of transmission, the speed ratios of the various gears are arranged in equal steps, with the aim of maintaining a common stage ratio between the upper and lower gears.
For multi-speed transmission gear, the total transmission ratio. Since its development, the two-box type compound transmission consisting of a main box and a rear auxiliary box has become the main form of a multi-speed transmission. Its structure can be a secondary box composed of cylindrical helical gears, which can be of a split-speed type, or it can be Segmented, now mainly the latter, segmented can also be a planetary gear reduction mechanism. The operating mode of the operation is a two box part of the block. As the main block operation, according to the driving conditions, the differential speed box is used to interpolate the speed, so it is not a gradual operation of a block, these driving conditions are the road When the change of working conditions requires half a block, when the slope changes little when climbing, when passing over the same line with other cars, it is necessary to overtake.
The multi-speed gearshift transmission is a dual-mode single gearshift operation. The driver can only increase the number of gears to a single gear by dialing the gearshift handle on the preselected differential switch. In operation, the gearbox can only divide a certain gear, not necessarily To shift gears progressively, shifts are simplified. Three-box compound multi-speed transmission, with a main box in the middle, a split-speed auxiliary box at the front, and a stepless sub-box at the rear, is now basically set and modularized, with one box, two boxes, and three boxes. With the change of speed ratio, many variant gearboxes can be formed on one load level.
From the speed characteristics, it can be seen that the speed of the engine is between the average speed and the average speed of the engine. The average power utilization rate can be found from the graph. When using a speed ratio transmission with a total speed ratio, the ratio of the speed ratio can be known. The average power utilization rate rises to the sum of the speed ratios when researched for gears, the number of transmissions increases, and the total speed ratio also increases, while the stage ratio decreases as the number of gears increases, as shown in the figure. As the value decreases, the shift is more convenient because the difference between the upper and lower speeds decreases.
In general, a gear box is used to form a gear in front of the transmission, and of course other combinations are also used. The gear ratio of a multi-speed transmission is not strictly proportional to the number of stages. Generally, there is a gear ratio closer at the high gear end. The ratio of the time used by the high gear end of the transmission accounts for most of the time. This can achieve better results in improving the average speed and saving fuel consumption. The shift operation is easy, but the driver must also perform certain training, especially the three-box multi-speed transmission, because the driver must always grasp the position of the gear.
As the gear increases, its cost must also increase. From experience in foreign countries, it is proven that transmission costs increase, but the overall cost of operation is reduced, and the resulting benefits are greater than those of multi-speed transmissions. The impact of the development of the economic situation in the future on the development of multi-speed gearboxes In the past planned economy era, fuel consumption accounts for the total cost of motor transport companies. This is an important indicator. With the current road maintenance fees for automobile transportation, the With the implementation of the fuel tax, the proportion of fuel taxes and costs will be greater, and the use of multi-speed gearboxes will be more economical.
Suggestions for the development of China's multi-speed transmission The stock of China's medium- and heavy-duty trucks is not small, the power is generally, and the total mass of actual trains is greater than that. First-step transmissions with two-cassette substations with sub-sections can be developed first. In the future, multi-port transformers should be designed with a modular design. The main box is a block, a two-cassette type with a rear-staged sub-tank, and a multi-speed transmission with a gear and a block for the future development. The split-type auxiliary box has room for the development of a three-box type.
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