Abstract: Proportional valve was the core component of the large diesel engine piston pump. The performance of the spool valve affected the hydraulic operating system. For the influence of proportional valve orifice on flow characteristics, the flow characteristics of proportional valve with different port structures were analyzed by means of numerical simulation and experiment. Firstly, based on the Schnerr-Sauer cavitation model of twophase flow in Fluent, the cavitation and flow characteristics of the valve under three different throttles were analyzed. Then, the proportional valve test rig was used to complete the flow test of the sample. Finally, the simulation results were compared with the experimental data. The comparison conclusion between simulation and experiment was obtained. The reliability of the simulation results was verified. The results show that the cavity volume of the proportional valve has no effect on the flow characteristics. The three throttles are fully open, and the flow of the valve is 9.56 L/min. The throttle shape of proportional valve affects the flow characteristic curve. The minimum flow coefficient of triangular valve port is 0.66. The flow coefficient of rectangular valve port is more than 0.7. The second-order rectangular valve port can control the flow linearly and accurately in low condition, and respond quickly in high condition. The secondorder rectangular valve port is more suitable for large diesel engine piston pump.

Key words:  piston pump;proportional valve;flow characteristics;hydraulic operating system;cavity model;throttle orifice