Dynamic and Static Characteristics of Double Push Rods Electromechanical Converter

Abstract

Due to the influence of material characteristics and winding power, single output electromagnet has limited ability to improve the dynamic characteristic of electro-hydraulic valve. Therefore, an electromechanical converter with double push rods is proposed in this paper, which can simultaneously output two electromagnetic forces, can push or pull the valve core and sleeve according to the current direction and realize rapid operation of load. According to the electromagnetic principle and the magnetic circuit analysis method, the mathematical model and equivalent circuit of the electromechanical converter with double push rods are established. Through the finite element simulation model of the electromechanical converter with double push rods with the same magnetization directions, the changing rules of its magnetic field distribution and force-displacement behaviors are studied and analyzed. According to the analysis results, the electromagnetic mechanical parameters and mechanical structure of the electromechanical converter with double push rods are determined, and the prototype is made. The test platform for the push-pull characteristics of the electromechanical converter with double push rods is built, and its static and dynamic characteristics are tested and analyzed. The results show that the thrust and pull output characteristics of the internal and external push rods are basically consistent with the simulation output, and proportional to the current density of the coil; the push-pull hysteresis of internal and external push rods output force is less than 5%; and the dynamic time response characteristics of the displacement and force are obtained. The hysteresis effect of output force is improved effectively through the H bridge drive control circuit modulated by PWM. Compared with the displacement response of a singlewinding electromagnet with a similar volume, it can effectively improve the dynamic displacement response. Followup work will further optimize the structure of the electromechanical converter and test the corresponding pilot valve. The research results provide a new theory for improving the output characteristics of electro-hydraulic pilot valve and have an extremely high engineering application value and broad application prospect.

Review of Recent Advances in the Drive Method of Hydraulic Control Valve

“…When adding a displacement amplification link, it not only reduces the efficiency of the mechanical drive but may also reduce the control accuracy. Therefore, when the spool movement stroke is [136]. 1.…”

“…There is a high-pressure orifice and a low-pressure orifice in the spool, and spool rotation changes the opening of the high-pressure and low-pressure orifices, thus changing the pressure at both ends of the spool, as shown in Figure 12. Wang XP et al [136] proposed an electro-mechanical converter with two pushrods. The inner coil controls the movement of the inner rod, and the outer coil controls the movement of the outer rod.…”

“…However, for general spool drive occasions, the conventional drive method can meet the requirements, and there is no need for a complex drive method. [136]. 1.…”

A Review of Pilot-operated Hydraulic Valves – Development, Challenges, and a Comparative Study

“…On this account, both of these actuators are recommended to be utilized in the Pilot stages in case of high flow demands. By the same token, Wang et al proposed an electromechanical converter with double push rods (20N force) to actuate the Pilot stage [156].…”