Abstract
In this paper, a novel maglev coupling based on the opposed Halbach array is proposed as the interface between the linear electro-mechanical converter and 2D valve body. This non-contact maglev coupling possesses several advantages over existing mechanical couplings such as zero friction and wear, low vibration and noise, and no lubrication, which is expected to greatly improve the control accuracy and life cycle of the 2D valve. A detailed analytical model of maglev coupling is established based on the electro-magnetic theory. Firstly, the permanent magnets of the Halbach array is decomposed into several types of basic elements to obtain their individual analytical expressions, which are then re-superimposed into the whole coupling to obtain the analytical formula of torque–displacement characteristics. In order to obtain maximum output torque of maglev coupling, a parametric analysis was performed using an analytical model and optimal pitch angle and shifted distance was explored and found. To verify the correctness of the analytical modelling and parametric analysis results, the torque–displacement characteristics were also studied through both the FEM simulation and experimental approach. The results of analytical modelling, FEM simulation and experiment were in a good agreement, which shows that the maximum magnetic torque can reach about 0.579 N·m when the external armature displacement is 1 mm. The research work provides an important reference for the future application of maglev coupling in a 2D valve.
Highlights
The electro–hydraulic control system has been widely used in crucial industries such as aerospace, defense, ship, large-scale power plant, and material testing machines [1,2,3].As key control components, electro–hydraulic servo and proportional valves play a decisive role for the performance of the whole system [4,5]
Since the magnetic force generated by the electro-mechanical converter (EMC) is not sufficient enough to directly conquer the influence of Bernoulli force and friction force brought by high pressure and large flow rate condition, these valves need to be designed as pilot operated configuration where an extra pilot stage is supplemented so that the magnetic force of EMC can be effectively amplified to a sufficient level to actuate the main spool [9,10]
After World War II, the demand for low-cost and robust electro–hydraulic control technology from the civil industry was growing strongly, and the proportional valve appeared where the low-cost proportional solenoid was used as a valve EMC [16,17]
Summary
The electro–hydraulic control system has been widely used in crucial industries such as aerospace, defense, ship, large-scale power plant, and material testing machines [1,2,3]. The pilot operated servo valves can be divided into nozzle-flapper valves, jet-pipe valves and deflector-jet valve, all of which are actuated by the torque motor These valves are primarily aiming at aviation industry and feature very fast dynamic response and high control accuracy [11,12]. Since the spool of the 2D valve physically functions as both the pilot stage and main stage, it features simplicity and high power-to-weight ratio [26,27] This configuration needs to design a spiralshape sensing groove on the sleeve inner surface in order to regulate pressure in the control chamber.
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