Abstract:  Aiming at the optimization problem of spool valve flow force, the flow field characteristics of non-full-circumferential opening and internal flow spool valve were studied,the structure of the valve sleeve was optimized. Firstly, a two-phase flow model was adopted, the movement state of the spool was simulated by using dynamic grid technology and UDF function, the transient flow field under the movement of the spool was calculated through simulation, and the steady flow field was analyzed when the spool is stationary. Then the influence of spool velocity,flow rate and orifice opening on flow force was studied. Finally, a method of changing the oil inlet hole of the valve sleeve from a straight hole to an oblique hole was proposed to optimize the flow force. The flow force at different inclination angles and valve openings were compared. The research results show that the steady state flow force of the spool valve is larger than the transient flow force, but the transient flowforce can be relatively large when the spool moves quickly with a large flow; and the opening degree is less than 0.5 mm, so its effect can not be ignored. The optimized valve sleeve structure can effectively reduce the flow force, and the optimization effect is best when the tilt angle is in the range of 15°~20°, which provides a useful reference for the optimization design of the spool valve structure.

Key words: spool valve;flow field characteristics;valve opening;flow force;valve sleeve structure;tilt angle