Abstract
The magnetic circuit of existing linear force motors does not consider the issue of energy utilization of permanent magnets, and the structure is complicated. To achieve high energy utilization and simplify the structure, this paper presents a novel magnetic circuit topology for the linear force motors of electro-hydraulic servo-proportional valves. In order to rapidly and accurately calculate the static characteristics of the force motor, an analytical model is established by using the equivalent magnetic circuit method. The model comprehensively considers the magnetic leakage effect, edge effect, and permeability nonlinearity. A prototype of the force motor is designed and manufactured, and a special experimental platform is built. The prototype force motor has a linear force-displacement characteristic and the output force increases with the increase of the excitation currents, which can reach about 41 N at 2 A. This indicates that it is suitable as an electro-mechanical converter for electro-hydraulic servo-proportional valves. Moreover, the analytical model is used to perform parameter optimization and calculate the magnetic flux density in the working air gap and the force-displacement characteristics under different excitation currents. The results are in good agreement with the electromagnetic field finite element simulation and experimental results. They indicate that the analytical model can rapidly and accurately predict the static characteristics of the force motor. The research work provides good reference means for the design of magnetic circuit topology with consideration of the high energy utilization of permanent magnets, and also the accurate analytical modeling of valve electro-mechanical converters.
Highlights
Since its advent, electro-hydraulic control technology has occupied a high-end position in electro-mechanical transmission and control technology with its high power-density, large output force, and excellent static and dynamic characteristics
The servo-proportional valve has appeared [10,11]. This valve features a direct action mechanism actuated by a linear electro-mechanical converter (LEMC), and the spool position is a closed-loop controlled by the displacement sensor
LPM ofutilization electro-hydraulic servo-proportional are properly considered together so that the potential contributed to the external valves, where the structural simplicity andmagnetic energy utilization of the permanent magnet magnetic circuit can be maximized asthat much possible.potential
Summary
Electro-hydraulic control technology has occupied a high-end position in electro-mechanical transmission and control technology with its high power-density, large output force, and excellent static and dynamic characteristics. Compared with the proportional solenoid, the configuration of the LFM features a single coil and double permanent magnet to constitute a differential magnetic circuit, which has large thrust force and fast dynamic response, and reduces the control current and coil heating [19]. The latter is more similar to a bi-directional proportional solenoid structure, which is characterized by a single permanent magnet and double-coil winding These LFM configurations have common shortcomings: firstly, their structure is too complicated, with the yoke being composed of multiple parts; secondly, the existence of radial working air gaps greatly increases the coaxiality between armature and yoke components, which improves the manufacturing cost. LPM ofutilization electro-hydraulic servo-proportional are properly considered together so that the potential contributed to the external valves, where the structural simplicity andmagnetic energy utilization of the permanent magnet magnetic circuit can be maximized asthat much possible.potential.
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