Simulation and Experimental Testing of an Actuator for a Fast Switching On-Off Valve Suitable to Efficient Displacement Machines

Digital Displacement (DD) fluid power machines are upcoming technology, improving the efficiency compared to traditional variable displacement machines, especially at low displacements where currently available fluid power pumps/motors suffer from mediocre efficiency. This efficiency improvement is made possible using independent electronically controlled seat valves for each pressure chamber, which is controlled corresponding to the rotation of the crankshaft. By control of these pressure chamber seat valves, the total displacement are controlled in discrete steps, and the pressure chambers not contributing to the displacement are not pressurized, which has been shown to improve the efficiency. To make this type of displacement control possible and energy efficient, the seat valves must be fast switching (ms range) and exhibit a very low pressure loss during operation, setting strict requirements for the valve design process. In this paper simulation of such fast switching valve is presented and the transient actuator performance is experimentally validated against transient Finite Element Analysis (FEA). Models predict a switching time of approximately 1ms for the valve and a pressure loss of 0.5 bar at 600 l/min, leading the way for highly efficient switching valves in DD machines.