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首页> 外文会议>2001 Fall Technical Conference of the Asme Internal Combustion Engine Division, 2001, Sep 23-26, 2001, Argonne, Illinois >ENGINE FRICTION CHARACTERISTICS UNDER COLD START CONDITIONS
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ENGINE FRICTION CHARACTERISTICS UNDER COLD START CONDITIONS

机译：冷启动条件下的发动机摩擦特性

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摘要

Most studies of engine friction have been carried out at fully-warm operating conditions. Relatively little attention has been given to frictional losses when the engine is running cold, although these can be considerably higher and have a strong influence both on cold-start characteristics and fuel consumption during warm-up. The losses which effect the indicated load on the engine are rubbing losses and loads associated with driving auxiliaries. The equivalent frictional mean effective pressures (fmep) are generally highest during the first seconds of engine operation. These decay rapidly onto a characteristic variation which depends upon oil viscosity, and which fmep follows throughout the warm-up period. The oil viscosity can be evaluated at the bulk temperature of oil in the sump or main gallery. Breakdown motoring tests have been carried out on a series of diesel engines to examine how the friction contribution of various sub-assemblies in the engine contribute to the total and how this varies with temperature and speed. Tests were carried out using a compact cold cell and engine motoring facility. The engine was cold soaked to a target test temperature and then motored to a target speed and the variation of motoring torque recorded. Sets of tests were carried out at several stages of breaking the engine down. This enables the contributions due to the valve train, piston and big end assembly, crankshaft, fuel injection pump, and auxiliary load to be determined.
机译：发动机摩擦的大多数研究都是在完全温暖的工况下进行的。发动机冷运行时，摩擦损耗的关注相对较少，尽管这些损耗可能更高，并且对暖机过程中的冷启动特性和燃油消耗都有很大影响。影响发动机指示负载的损耗是摩擦损耗和与驱动辅助装置相关的负载。等效摩擦平均有效压力（fmep）通常在发动机运行的最初几秒钟内最高。这些迅速衰减成取决于油粘度的特征变化，并且在整个预热期间遵循fmep。可以在油底壳或主油道的整体温度下评估油的粘度。已经对一系列柴油发动机进行了故障驱动试验，以检查发动机中各个子组件的摩擦贡献如何对总贡献以及如何随温度和速度变化。使用紧凑型冷室和发动机机动设施进行了测试。将发动机冷浸至目标测试温度，然后将其驱动至目标速度，并记录驱动扭矩的变化。在分解发动机的几个阶段进行了一系列测试。这样就可以确定由于气门机构，活塞和大头组件，曲轴，燃油喷射泵和辅助负载引起的影响。

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