Theoretical and experimental research on the cartridge two-dimensional (2D) electro-hydraulic servo valve

Abstract

A cartridge 2D EHSV based on torque motor is proposed in this paper, which is keeping the advantages of conventional 2D valve, such as compact structure, high power-to-weight ratio, and excellent dynamic characteristics. In order to explore its dynamic characteristics, the design concept and operating principle of the cartridge 2D EHSV valve is presented first. Then the mathematical model of cartridge 2D EHSV valve is derived, especially the rotational viscous damping coefficient which is studied in detail. The simulation results of the open(closed)-loop model show that the support pressure plays an insignificant role in the dynamic characteristics of 2D EHSV, only the phase bandwidth of the closed-loop model increases. And the rise time of the open-loop model is about 10 ms, and the frequency bandwidth is about 40 Hz, while the rise time is about 4 ms and the frequency bandwidth is about 100 Hz of the closed-loop model. Furthermore, as verified by experimental results, the rising time of the step response is about 7 ms and the bandwidth is approximately 38 Hz under the open-loop control, while that is 6 ms and 117 Hz for 25% input signal under the close-loop control. Finally, the difference between the experiment and the simulation is discussed. It is concluded that the cartridge 2D EHSV has excellent dynamic characteristics.