Design of Over Center Valves Based on Predictable Performance

A typical over center valve system and a time domain simulation model is introduced together with a hypothesis that flow force compensation should reduce the inherent oscillatory behavior of such systems. A few results are shown from a parameter study that confirms this assumption and an approach to design over center valve geometries that have negative flow forces is presented with emphasis on predictability. In conclusion it is made clear that negative flow forces in the over center valve cannot solve the instability problem in general, however, it might very well be a method like lowering the pilot ratio, that can be used to application specific instability problems.