車輛工程專業(yè)畢業(yè)設(shè)計外文翻譯---自動變速器如何工作-文庫吧
2025-04-16 15:56 本頁面
【正文】 h is released, the bigger sun gear is free to spin in the opposite direction of the turbine Second Gear This transmission does something really neat in order to get the ratio needed for second gear. It acts like two plaary gear sets connected to each other with a mon pla carrier. The first stage of the pla carrier actually uses the larger sun gear as the ring gear. So the first stage consists of the sun (the smaller sun gear), the pla carrier, and the ring (the larger sun gear). The input is the small sun gear。 the ring gear (large sun gear) is held stationary by the band, and the output is the pla carrier. so the formula is: 1 + R/S = 1 + 36/30 = :1 The pla carrier turns times for each rotation of the small sun gear. At the second stage, the pla carrier acts as the input for the second plaary gear set, the larger sun gear (which is held stationary) acts as the sun, and the ring gear acts as the output, so the gear ratio is: 1 / (1 + S/R) = 1 / (1 + 36/72) = :1 To get the overall reduction for second gear, we multiply the first stage by the second, x , to get a :1 reduction. This may sound wacky, but it works. Third Gear Most automatic transmissions have a 1:1 ratio in third gear. You39。ll remember from the previous section that all we have to do to get a 1:1 output is lock together any two of the three parts of the plaary gear. With the arrangement in this gear set it is even easier all we have to do is engage the clutches that lock each of the sun gears to the turbine. If both sun gears turn in the same direction, the pla gears lockup because 外文資料 7 they can only spin in opposite directions. This locks the ring gear to the plas and causes everything to spin as a unit, producing a 1:1 ratio. Overdrive By definition, an overdrive has a faster output speed than input speed. It39。s a speed increase. In this transmission, engaging the overdrive acplishes two things at once. If you read How Torque Converters Work, you learned about lockup torque converters. In order to improve efficiency, some cars have a mechanism that locks up the torque converter so that the output of the engine goes straight to the transmission. In this transmission, when overdrive is engaged, a shaft that is attached to the housing of the torque converter (which is bolted to the flywheel of the engine) is connected by clutch to the pla carrier. The small sun gear freewheels, and the larger sun gear is held by the overdrive band. Nothing is connected to the turbine。 the only input es from the converter housing. Let39。s go back to our chart again, this time with the pla carrier for input, the sun gear fixed and the ring gear for output. Ratio = 1 / (1 + S/R) = 1 / ( 1 + 36/72) = :1 So the output spins once for every twothirds of a rotation of the engine. If the engine is turning at 2020 rotations per minute (RPM), the output speed is 3000 RPM. This allows cars to drive at freeway speed while the engine speed stays nice and slow. Reverse Reverse is very similar to first gear, except that instead of the small sun gear being driven by the torque converter turbine, the bigger sun gear is driven, and the small one freewheels in the opposite direction. The pla carrier is held by the reverse band to the housing. So, according to our equations from the last page, we have: Ratio = R/S = 72/36 = :1 So the ratio in reverse is a little less than first gear in this transmission. Gear Ratios This transmission has four forward gears and one reverse gear. Let39。s sum
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鄂ICP備17016276號-1