基于超声波反射信号的曲轴油膜厚度测量系统

Oil film thickness measurement system of crankshaft based on ultrasonic reflection signal

曲轴处的润滑状态关系到内燃机的性能。该文研发了一种基于超声波反射信号的曲轴油膜厚度测量系统以实时监测油膜厚度的变化。基于声学理论,导出多层介质中油膜厚度与声反射系数的关系,并给出弹簧模型、共振模型和相移模型的使用方法。针对曲轴油膜厚度在0~50μm的约束,采用中心频率为1.056 MHz的超声双晶直探头来产生和接收超声信号,加工出具有4道不同深度环形槽的长轴来获取油膜厚度与声反射信号频谱峰值的函数关系。所拟合的线性模型被嵌入LabVIEW软件中用于计算油膜厚度。经检验,该测量系统的测量相对误差在10%以内,能较好地测量油膜厚度。

The performance of an internal combustion engine is related to the lubrication state of the crankshaft. In this paper, a thickness measurement system is developed using an ultrasonic reflection signal to monitor the change of oil film thickness in real time. Based on acoustic theory, the relationship between oil film thickness and acoustic reflection coefficient in multilayer media is derived, and the application methods of the spring, resonance, and phase shift models are given. For the crankshaft, the oil film thickness ranges from 0 to 50 μm, an ultrasonic double crystal straight probe with a center frequency of 1.056 MHz is used to generate and receive the ultrasonic signal, and a long axis with four annular grooves with different depths is processed to obtain the functional relationship between the oil film thickness and the spectral peak of the acoustic reflection signal. To calculate the oil film thickness, the fitted linear model is embedded into LabVIEW software. The test shows that the relative error of the measurement system is less than 10%, and the oil film thickness can be measured well.