Abstract: In view of requirements for better position accuracy, response time and stability of hydraulic system, it is more important than ever to pay attention to bulk modulus of hydraulic oil. The effects of the bulk modulus of hydraulic oil on system performance are analyzed. Based on the theoretical model, studies on the effects of air content, pressure and temperature on bulk modulus are done though simulation. An online measuring device of bulk modulus of hydraulic oil is designed according to the definition of bulk modulus. The simulation and experiment results show that the method of analysis and measurement of bulk modulus provided is very useful to confirming the oil bulk modulus in real hydraulic system.

Key words: Bulk modulus of hydraulic oil, Hydraulic system, Online measurement, Simulation analysis