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一、前言在汽车和工程机械试验中,发动机转速是重要测试参数之一。转速测量误差较大,对评定发动机性能和其他技术指标有直接影响。因此,转速测量误差最好不大于1%。发动机台架试验,如在曲轴端部安装高次倍频式数字传感器,用数字测速仪测量,可直接读出每分钟转数,测量误差也能满足要求。但是,在用汽车和工程机械的发动机,难以安装这种传感器,因此,精确测量其发动机的转速比较困难。虽然用频闪法测速仪可以对发动机冷却风扇的转速做精确测量,但由于风扇和曲轴之间通过皮带轮传动,在发动机冲击角加速度的影响
I. Introduction In the automotive and construction machinery test, the engine speed is one of the important test parameters. The speed measurement error is larger, which has a direct impact on the evaluation of engine performance and other technical indicators. Therefore, the speed measurement error is best not more than 1%. Engine bench test, such as the installation of high-end frequency multiplier digital sensor at the end of the crankshaft, measured with a digital speedometer can be read directly to the number of revolutions per minute, the measurement error can meet the requirements. However, it is difficult to mount such a sensor on engines for automobiles and construction machinery, and therefore it is difficult to accurately measure the rotational speed of its engine. Although the stroboscope can make accurate measurements of the engine cooling fan speed, the influence of acceleration on the engine impact angle due to the transmission of the pulley between the fan and the crankshaft