Abstract: The electrical modulation valve can provide proportional output valve element displacement, flow, or pressure according to a continuously changing input electrical signal. It is the core component of electro-hydraulic proportional control technology. To remove the influence of pressure difference changes on the output flow, the traditional scheme is to use a pressure compensation valve, which increases the difficulty of both manufacturing and maintaining the valve. To solve this problem, a method of digital and mechanical redundancy control flow is proposed. Pressure sensors are installed at the inlet and outlet of the valve, and the controller adjusts the displacement of the valve element according to the pressure difference between the valve ports to realize high-precision control of the flow. A pressure compensation valve is installed in front of the valve, and a three-way solenoid valve is used to control the working of the compensation valve. In the case of sensor failure, the valve is switched to the mechanical compensation differential pressure mode, to control the flow and to achieve redundancy control. The system security is thereby improved. The feasibility of this scheme is verified through simulation and tests. The results show that, both for digital compensation and mechanical compensation, the output flow can be kept constant when the pressure difference changes, and the system has good static and dynamic characteristics. The principle can be applied to the displacement-flow feedback type electrical modulation valve, and can realize accurate control of the flow of the pilot valve and, finally, accurate control of the flow in the main valve.

Key words: Electrical modulation valve; Control characteristics; Co-simulation; Redundancy control

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