Suppression of pressure transients in on/off control of low-pressure water hydraulic cylinder

摘要

The paper analyses and tests experimentally two methods to suppress pressure transients in an on/off controlled water hydraulic cylinder. The on/off position control is realised with inexpensive two-way solenoid valves and the basic three-state control is used as a starting point. In the first method, termed as the modified three-state control, the control algorithm is modified such that two velocities are achieved with the same valves as in the three-state control. In the second method two damping volumes are added into the system via small orifices. The effect of the size of the orifice and damping volume on the damping factor of the system is analysed by using a linearised model. Results show that both methods significantly reduce the pressure transients. The drawback of the modified three-state control is that it is more sensitive to changes in the load force than the three-state control. The use of the damping volumes is effective in reducing the pressure transients but the position error increases slightly.