End cushioning

[Metehanbektas]

Hello guys,

another question from me. I have a piston accumulator, and it has an end cushioning at the end of stroke of oil side. See image. I have calculated kinetic energy of the system and got the pressure peak. Normally in cylinder, we have a cushioning hole, through this oil flows. But in my case, i dont have it. How should i measure the tolerance of hole and piston ?

 

[tbuelna]

Seems pretty straightforward. Initially the flow will be limited by the area and length of the hole in the cap. Then as the piston approaches the cap, the flow will be limited by the circumferential gap between the upper edge of the piston protrusion and the hole chamfer in the cap. Once the piston protrusion edge passes into the cylindrical section of the hole in the cap, the flow area is the area of the hole minus area of the piston protrusion at the circumferential gap. The flow characteristics will change as the axial overlap between the piston protrusion and the cylindrical hole increase.

You can always fine tune the flow by tapering the piston protrusion OD.

 

[73lafuite]

Please find calculation for the flow in your application