Abstract:Based on the fractal characteristic of spool and valve chamber microscopic surface for hydraulic excavator multi-way valve, a mathematical model for the surface of spool and valve chamber was established via the function of W-M. Through Matlab software programming, three-dimensional surface topography model was established, and the effect of different fractal dimension on the surface topography of spool and valve chamber was compared. The gap flow model on the gap between the spool and valve chamber was established. The change of pressure and velocity of the hydraulic oil flowing in the gap was analyzed by Fluent software. The results show that along with increasing of the fractal dimension, the surface roughness of valve spool is in the trend of increasing. The surface roughness has great effect on pressure drop of the hydraulic oil flowing in the gap, and certain effect on oil velocity. The larger the surface roughness of spool and valve chamber is,the greater the pressure drop of oil, and the smaller the oil velocity is.