Electrohydraulic Vibration Exciter Controlled by 2D Valve

The working frequency of the electrohydraulic vibration exciters conventionally constructed by a servo valve and a hydraulic cylinder or a motor is to a large extent limited to fairly narrow range by the frequency response capability of the servo valve. A scheme of electrohydraulic vibration exciter using a 2D valve (two-dimensional control valve) to control a hydraulic actuator is therefore proposed to enhance the working frequency by a large margin. In the 2D valve, the rotary and sliding motions are independently exploited to control the frequency and the magnitude of the agitated vibration respectively. The frequency of the 2D valve controlled vibration exciter is determined by the rotary speed, number of grooves distributed on a spool land and coupled pattern of the groove number on the spool land and the windows number on the spool sleeve. By adjusting these factors in the 2D valve design, the proposed scheme of vibration exciter is apt to realize high-frequency vibration. Taking the electrohydraulic vibration exciter formed by the 2D valve and a symmetrical cylinder as an example, theoretical and experimental investigations are carried out to the case that the elastic force constitutes the main part of the load. It is clarified that the change of the direction of elastic force has a significant effect on the excited wave form. Although the rate of throttling areas of the 2D valve varied in a triangular waveform approximately as the spool rotates, the ascent and descent slopes of output force or displacement wave demonstrates somewhat inconsistency because of the changing direction of the elastic force. The inconsistency becomes the most manifest when the linear opening of the 2D valve reaches a critical point and weakens when it is reduced.