Research on a large torque surface-mounted magnetic screw mechanism and its application on 2D flow valve

A novel surface-mounted magnetic screw mechanism (SMMSM) with large output torque and high magnetic energy utilization is proposed. To study the torque-displacement characteristics, the analytical model of SMMSM is derived based on the equivalent magnetic charge theory, virtual displacement method and superposition principle. The influence of the spiral angle of SMMSM, number of magnetic bar, thickness of magnetic bar, and thickness of air gap on the torque are explored, and key structural parameters are selected to design and manufacture the prototype. A static and dynamic experimental platform is built, and the experiment show that the maximum output torque of the SMMSM can reach 1.185 N m at a displacement of 1 mm, and the step response time is 27.5 ms, which are substantially superior to the existing maglev couplings. Finally, the SMMSM is applied to 2D flow valve. The experiments show that the SMMSM-based 2D flow valve has the advantages of large flow rate, high system pressure and fast dynamic response: the maximum flow rate is 167.8 L/min at a system pressure of 25 MPa, the step response time is 16.5 ms, and the amplitude-frequency width is 46.0 Hz, which is also superior to the existing maglev 2D flow valves in terms of these performance indexes. The research indicates the SMMSM-based 2D flow valve can be used as a potential solution for electro-hydraulic servo-proportional valves.