## Open/Closed center circuits

Summary:

• Open/Closed center circuits – what does it mean?
• Which one I use?
• What can happen if I connect my system to wrong center circuit?

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There are two types of valve circuits can be used to control your system: “Open center circuit” and “Close center circuit”.

## Proportional valve calculation

Calculations Notes:

• The formulas and algorithm of calculations you can find by this link.
• Pressure compensated pump with variable displacement is used as a source of pressure and flow.
• The spool lands work as orifices and have the same shape on both sides of the spool land.
• The same orifice coefficient (Cv) is used for both lands.

## New QuickDesign with SmartConnect from SUN

New QuickDesign with SmartConnect from SUN

SUN announced about new SmartConnect schematic tool for manifold design.

This is a very interesting feature which really simplifies the preparing work of manifold design. The online application is free and required a free registration only. Before this time it was a pretty complicate algorithm to indicate connections between cartridges’ ports. Now you just draw a hydraulic schematic (easy drag and drop SUN components) and with next step you get ready to use manifold design drawing set.

I used SUN manifold design before and tried to use it now with SmartConnect – I see the difference, and it is really improving and great feature.

I think the next step from SUN to be components’ placement optimization. I really like the idea of free online manifold design, but on the other hand, I found the complicated design from SUN has not optimal components placement and always manual correction required. And the problem with it – it hard to do in CREO because at the end we get STEP file which impossible (or very hard and uncomfortable) to modify. But anyways, this online application can give you some idea how to place components in the space and this is a good basis for your own manifold design. This is why I at least recommend to pay attention to QuickDesign with SmartConnect tool.

## Part 1. Proportional control of double acting hydraulic cylinder.

Fig.1. Double acting cylinder control.

The goal of the calculation is definition of a cylinder velocity at the current operating voltage at the valve’s solenoid.
For calculations we need to know: cylinder and valve parameters (take them from manufacturer catalog), values of forces at cylinder rod (load) and pressure drop at return line (can be assumed as zero if unknown).

Summary:
1.1. Hydraulic cylinder extension calculation.
1.1.1. Spool lands ratio.
1.1.2. Pressure drops at the spool lands
1.1.3. Balance of forces at the cylinder.
1.1.4. System pressure calculation.
1.1.5. Flow through spool lands: max. and at current voltage.
1.2. Hydraulic cylinder retraction calculation.
1.3. Full stroke time calculation.