The Dynamic Performance Simulation Of Screw Pump's Relief Valve

A three-screw pump is one kind of advanced positive displacement pumps, and have been widely used for the compact form,long life-span and small in vibration. In recent years,the massive research works about the three-screw pumps have been carried on in domestic and foreign.But most of the works focused on the design,process and measure in the screw's molded lines, and less on the interrelationships between the pumps and its accessories.This paper focused on and simulated the dynamic performance of the relief valves used for the<135> type three-screw pumps. Based on the simulation results with the Matlab/Simulink, the force of the screw rods caused by impact pressure was analysed, and learned about the interrelationship between the pump and the relief valve. The results are useful to guide the design of the pumps and the valves.To know the impact on the pump rods caused by the relief valves, a method of vector algebra has been used to get the model of the screw rods. With the model, the forces and deflections of the screw robs in normal working condition have been computed with surface integral. And the results are even closer to the actual condition of the pumps, it is available for the design on screw rods and bushes. A method to balance the radial forces on the screw rods was advanced, it is useful for reduction of wear between the screw rods and bush.During the study of dynamic performance of the relief valve, the regulation of the high-pressure domain's variation has been led into the established dynamic equations of the relief valve, and simulated the dynamic performance with the software Matlab/Simulink. From the result of simulation, the maximum impact pressure as the relief valve opened was obtained, the impact to the screw rods has been computed and the correlation between the high-pressure domain and the dynamic performance of the relief valves was verified, and some advices about the relief valves were given.At last, the simulation results were verified with a test about the pressure of high-pressure domain as the relief valve opened, and the results were credible.The research works in the paper give a new research area, and have directive significance for the design of the pump systems.