Bernhard Manhartsgruber, Andreas Plöckinger,
"A Test-Rig for the Characterisation of Fast Check Valves"
, in D N Johnston, K A Edge: Power Transmission and Motion Control - PTMC 2006, Seite(n) 335-346, 9-2006, ISBN: 08-6197-135-3
A Test-Rig for the Characterisation of Fast Check Valves
Sprache des Titels:
Power Transmission and Motion Control - PTMC 2006
While the measurement of the dynamic properties of a standard spool valve for directional flow control is a well defined task in the fluid power community, the characterisation of check valves is much less clear.
In the first case, the response of the spool position to various inputs like steps or sinusoids is measured. The comparison between the desired spool position (input) and the measured output is shown as a step response plot and/or as a bode diagram in the data sheet. The influence of a flow rate across the metering edges of the valve is often not shown in these figures, yet it is always present due to flow forces acting on the spool. However, the flow forces tend to influence mainly the magnitude of the transfer function between the desired and the actual spool position. The phase lag responsible for stability problems is only marginally affected. Therefore, the interaction between the controlled flow and the spool actuation is often neglected.
In the case of a check valve the situation is completely different. The only forces acting on the flow restricting element are the spring load and the forces exerted by the fluid. While it is in principle possible to measure the movement of the flow restricting element there is no
demand signal to compare with.
In the literature the dynamics of check valves is often characterised by the eigenfrequency of the spring-loaded restricting element not taking into account the interaction with the flow. This paper shows that there is a significant influence of the surrounding hydraulic fluid. Furthermore, details on a test rig and a measurement procedure for the dynamic characterisation of check valves are given.