内燃机运转中存在两类转速波动,即一个工作循环内的转速波动和相继循环间的转速变动.常用的转速表难以测定这些波动.本文介绍一种新测量仪器的原理,并分析了它的测量精度.该仪器曾在五种型号柴油机试验中应用,本文给出稳定工况、低速游车、突卸负载和起动过程等测量结果. There are two types of speed fluctuations in the operation of an internal combustion engine, namely, the speed fluctuations in one duty cycle and the speed changes in successive cycles. It is difficult to measure these fluctuations with the commonly used tachometer.This paper introduces the principle of a new measuring instrument and analyzes its measurement Accuracy.The instrument has been used in five models of diesel engine test, this article gives the stable operating conditions, low-speed travel, sudden load and start the process of measurement results.