Combined type flow valve for liquid of high-pressure large-flow alternating current servo direct-drive machine

The invention provides a combined type flow valve for liquid of a high-pressure large-flow alternating current servo direct-drive machine. An alternating current servo motor drives a push rod through the transmission of a thread and the push rod acts on a hydraulic transmission cavity which is sealed with hydraulic oil; when the push rod moves, the inner volume of the hydraulic transmission cavity is changed and a valve core moves to the same side to compensate the change of the volume, so that the movement of the valve core is controlled through controlling the movement of the push rod. The valve has the advantages of simple structure, accurate control and convenience for use, can directly use a computer to carry out digital control, has good buffering and positioning performances, can meet the requirements of positioning any point, can realize a closed ring system of electric feedback, and especially can be used for better solving the problem that the previous servo valve is sensitive to oil liquid pollution. The valve is wide in working pressure range and large in flow and can work under a very low oil supply pressure, and the dynamic performance is not greatly influenced by the low oil supply pressure; and the valve has fewer middle transmission links so that the efficiency of the system can be improved.