Quick Question

[dtengineering]

Originally Posted by Kersten

Is it possible, when using a piston, to retain the air instead of lose it so it will work faster instead of having to build up the energy over and over again?

Possible and FRC legal are two different things.

The short answer is yes, it is possible to retain some of the energy in the compressed air by venting it to a second-stage low pressure side of the pneumatics. I'm simplifying a bit here, but yes, it is possible to build a system that is more efficient than simply venting all "used" air to the atmosphere.

FRC has a few rules that make this challenging, one stating that all compressed air must come from the compressor, and another one stating that only the Clippard tanks may be used for storing compressed air.

So consider the situation where you have a cylinder pressurized to 60psi. Hook it up as normal, but then run the vent from the solenoid valve to another solenoid valve. This second solenoid valve can output to either a regulator set to 30psi feeding a storage tank on a low pressure side of the system, or to atmosphere.

When you change the direction of the first solenoid valve (to move the piston) the 60psi air in the extended part of the cylinder is directed through the second solenoid valve to the 30psi side of the system. When the pressure in the cylinder has dropped a bit, and some the energy in the compressed air has been recovered, then the second solenoid valve shifts and vents to atmosphere, allowing the piston to complete its stroke as normal. This might be legal, so long as it is not determined that the cylinder is acting as a storage tank, and so long as the piston on the cylinder is not 'pushed' in by an external force (thus compressing the air using something other than the compressor).

While I don't see a rule specifically prohibiting this, other than listed above, I would definitely get a Q&A ruling on it before planning to builld it into a robot.

But it IS possible to recover SOME of the energy stored in the compressed air.

Jason

P.S. On the "possible" vs. FRC legal... it is possible to set the working system pressure above 60psi, but not FRC legal. Now that our season is over, however, we have discovered that an extra 10psi or so in the launcher is... impressive.