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首页> 外文会议>The 2002 Global Powertrain Congress on Advanced Transmission/Drivetrain Systems Vol.21 Sep 24-26, 2002 Ann Arbor, Michigan USA >Layshaft Transmission Gear Ratio Selection
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Layshaft Transmission Gear Ratio Selection

机译：副轴变速比选择

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摘要

For a given application transmission ratios are selected to satisfy performance requirements of gradability, fuel economy, acceleration, and ease of operation. Back in 1951 Chrysler had established engine piston displacement per ton-foot as a measure of gradability and acceleration. This criterion was later revised and expressed as piston displacement per ton-mile (DPTM) for the convenience of graphical representation. The displacement formula is also presented in metric units as liters per kilogram kilometer (lPkgkm). Transmission ratio is selected such that along with a given engine size and tire size the desired performance and piston displacement are achieved. Gradability and launcha-bility vary directly with the displacement and improved launchability can favorably affect fuel economy. Also, this measure, better reflects the unboosted and part throttle launch performance of a vehicle as opposed to using the gradability formulas, which use wide open throttle torque. The unboosted (in case of turbocharged engines) or part throttle launch performance gives a better indication of performance and ease of launch for the more typical driving conditions of passenger vehicles. Typically piston displacement ranges from about 10in~3 per ton foot for a loaded truck to 45in~3 per ton foot for a passenger car in high gear. Experience has attested that a loaded truck in low gear should have higher displacement (approximately 75in~3 per ton foot) in order that the passenger car and trucks can use the same highway without undue aggravation. Given the piston displacement criteria in low and high gears the ratio spread can be calculated as a ratio of the displacements in low gear to high gear. Using the ratio spread we can proceed to calculate ratio steps in a manner such that they form a geometric sequence.
机译：对于给定的应用，选择传动比以满足可分级性，燃油经济性，加速和操作简便性的性能要求。早在1951年，克莱斯勒就确定了每吨英尺的发动机活塞排量，以此来衡量可爬坡度和加速度。此标准后来进行了修订，并以图形表示的方便性表示为每吨英里的活塞排量（DPTM）。位移公式也以公制单位表示，以升/千克公里（lPkgkm）为单位。选择传动比，以便与给定的发动机尺寸和轮胎尺寸一起获得所需的性能和活塞排量。爬坡性和可发射性随排量而直接变化，而可发射性的提高可有利地影响燃油经济性。同样，与使用可开度节气门扭矩的可分级性公式相比，该措施更好地反映了车辆的无节气门和部分节气门启动性能。对于乘用车更典型的驾驶条件，未增压（对于涡轮增压发动机而言）或部分节气门启动性能可以更好地指示性能，并易于启动。通常，活塞的位移范围从装满卡车的每吨英尺约10英寸3到高档乘用车的每吨英尺45英寸3。经验证明，低速装载的卡车应具有更高的排量（每吨英尺约75in〜3），以使乘用车和卡车可以在不增加过度行驶的情况下使用同一条高速公路。给定低速档和高速档的活塞排量标准，可以将比率扩展计算为低速档与高速档的排量之比。使用比率扩展，我们可以以形成几何序列的方式继续计算比率步长。

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