Full circumferential reluctance maglev coupling for 2D proportional flow rate valve: Design, modelling and experimental validation

A novel full circumferential reluctance maglev coupling (FCRMC) is proposed in this paper, which not only meets the requirements of force transmission and valve position feedback of two-dimensional (2D) valve but also has the advantages of closed-loop magnetic circuit and high magnetic energy utilization rate. To investigate the torque-displacement characteristic of FCRMC, a detailed analytical model based on the equivalent magnetic circuit method is formulated, which considers the leakage flux effect, edge effect, and magnetic permeability nonlinearity. The effects of the inclination angle, width, air gap, and number of teeth on the torque are explored by the analytical model, and appropriate structural parameters are selected to design and manufacture the prototype. A dedicated test bench is built and the static/dynamic characteristics of FCRMC are tested. The experimental results show that the FCRMC prototype has a step velocity of 20.8 × 10−3 mm/ms, a torque-volume ratio of 8.47 × 10−3 N m/cm3, a torque-permanent magnets(PMs) volume ratio of 0.050 N m/cm3, and a step velocity-PMs volume ratio of 2.63 × 10−3 mm/ms·cm3. Finally, to verify the feasibility of the FCRMC in real work situations, the FCRMC is applied to a 2D electro-hydraulic proportional flow valve. The experimental results show that, at 15 MPa, the no-load flow of the valve is 82.4L/min, with a hysteresis of 3.8 %, a step velocity of 17.5 × 10−3 mm/ms, and amplitude and phase frequency widths of 22.4 Hz and 26.5 Hz.