Abstract: The technique for the on-line measurement of bulk modulus of hydraulic fluid is very important for the dynamic simulation of hydraulic systems, system monitoring and adaptive control etc. In the paper the R-C network is used to accomplish the on-line measurement of βe and the average value and fitting curve expressing the relationship of βe with pressure is proposed. Furthermore, the random error of measured results is briefly discussed.

Key words: 测量方法, 体积模量, 液压油