A rotary valve and its orifice design for high-frequency asymmetric vibration waveforms with electro-hydraulic vibrator

High-frequency asymmetric vibration waveforms are often required in engineering practice. However, when asymmetric vibration waveforms are needed, conventional electro-hydraulic vibrators can only achieve low frequencies, due to the limitations imposed by the inertia in slide servo valve. In this paper, to generate high-frequency asymmetric vibration waveform, a rotary valve is proposed as the control valve of the electro-hydraulic vibrator. Then the parameter relationship between the valve orifice and the vibration waveform characteristics is investigated. Based on the shape and amplitude of the asymmetric vibration waveform, the geometric parameters of the orifice are analytically solved. The results show that with rotary valve, high frequency can be easily achieved with the spool rotation at a uniform high speed, and the frequency range of the electro-hydraulic vibrator can be greatly extended. The proposed rotary valve and its orifice design method can be effectively applied to electro-hydraulic vibrators with different structural parameters. It enables the generation of the desired high-frequency asymmetric vibration waveforms. The vibration waveform error is lower than 6.5% when the vibration frequency is higher than 70% of the natural frequency, and the error of the calculated amplitude obtained from the orifice design method is lower than 7%.