| Summary: | To realize rotary and linear motions of a single spool for improving a proportional displacement of the spool, a new structure of ball screw compression–torsion coupling is proposed, which is used in the two-dimensional electro-hydraulic proportional directional valve. Its principal is based on changing the spiral angle of the raceway to magnify the thrust of a wet proportional electromagnet and realize the rotary to linear motion of a single spool. In addition, because of the rolling friction instead of the sliding friction, the friction resistance is reduced. The mathematical model of the valve is established and the characteristics of the valve are simulated and analyzed by MATLAB. Theoretical and experimental results show that the no-load hysteresis of the ball screw compression–torsion coupling is up to 1% under the flutter compensation. At the system pressure of 21 MPa, the flow hysteresis of the valve is less than 5%, and the nonlinear degrees of the input displacement of electromagnet and the output displacement of the valve core are both less than 1%. The width of the valve corresponding to −3 dB and −90° is about 12 Hz, and the step response time of the valve is about 0.45 s without overshoot.
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