Characteristic investigation of a magnetostrictive fast switching valve for digital hydraulic converter

In order to adapt the frequency requirements of fast switching valve applied to the digital hydraulic converter, a 2/2 way fast switching valve driven by giant magnetostrictive material was performed in this article. The finite element simulation of the fast switching valve’s electromagnetic field and flow field was carried out. In addition, the integrated analytical model of giant magnetostrictive material–fast switching valve coupling with enhanced transmission line method was built in MATLAB/Simulink. The displacement and pressure-flowrate characteristics of giant magnetostrictive material–fast switching valve were discussed and validated in the experiments. The results indicated that the nonlinearity magnetization presents a positive relationship with the driving current before it reaches the saturated state, and the hydraulic force at the expected opening is far less than output force caused by magnetostrictive strain. The experimental valve displacements are in good agreement with obtained results from analytical model, which reveals that the analytical model is accurate enough to predict the main performances of the fast switching valve. The maximum valve displacement without supply pressure is up to 68 µm, which attenuates moderately with the growth of supply pressure. The experimental responses of the displacement and the pressure of giant magnetostrictive material–fast switching valve are less than 1 ms. The amplitude of output flowrate is 8.1 L/min at the frequency of 100 Hz when the pressure drop across giant magnetostrictive material–fast switching valve is 6 MPa theoretically. Similarly, the maximum transient flowrate derived from experiments reaches 8.2 L/min at pressure drop across giant magnetostrictive material–fast switching valve of 5.9 MPa, which is basically consistent with that predicted by analytical model. These reveal that the giant magnetostrictive material–fast switching valve can be utilized in the digital hydraulic converter to improve the system’s efficiency.