pneumatic problem

[koka230]

well we have a shooter on our robot that is pneumatic well when we tested it before, we just put the system up to 60 psi without a regulator instead of having 120 in the tanks and regulated down to 60 just to test it, well when we tested it that way the ball shooter worked but when we put 120 in the tanks and regulated it down to 60 psi it did not work, oh and by the way we have 3/4 with 6in stroke cylinder and we are not getting the speed we need

please help and give some insight on this problem

[robert.hatchett]

Sounds like the stored air is not able to pass through the regulator at the speed your unregulated test was able to provide.

This is a function of Cv through the regulator.

Unfortunately, since you are required to use the KoP regulator you may have to rework your design to compensate. Also unfortunately, there is no easy solution to this and may require a revisit to your design.

If you could post more details about your system, perhaps there might be more insightful answers to your problem.

[Joe G.]

One possible solution would be to put accumulators on the 60psi side of the system. This would result in the momentary pressure drop on the 60psi side to be less, keeping pressure in the cylinder high throughout the cylinder's firing.

[Daniel_LaFleur]

Originally Posted by robert.hatchett

Sounds like the stored air is not able to pass through the regulator at the speed your unregulated test was able to provide.

This is a function of Cv through the regulator.

Unfortunately, since you are required to use the KoP regulator you may have to rework your design to compensate. Also unfortunately, there is no easy solution to this and may require a revisit to your design.

If you could post more details about your system, perhaps there might be more insightful answers to your problem.

Robert is correct. The Cv of the regulator is an issue if you are going to try and launch pneumatically.

I would suggest using 2 accumulators upstream of the regulator (120 PSI side) and 2 accumulators downstream of the regulator (60 PSI side). That may give you enough capacity to both shoot and recover quickly.

[koka230]

recovery isn't the issue its just the shooting speed

[Joe G.]

Shooting speed would be increased, though, if pressure in the cylinder was high throughout the entire stroke. The more storage space there is on the 60psi side, the less the pressure will go down as the cylinder moves, and the faster the cylinder will move throughout the entire stroke.

[koka230]

is it possible for us to get a different cylinder will that help too

[Chris Fultz]

if there is a way for you to keep the rod end of the cylinder open (do not route the tube to the solenoid), your cylinder will extend much quicker.

with the cylinder plumbed to a double acting solenoid, the vent air (when you extend the cylinder) is restricted through the solenoid.

There are a few ways to do this from a system standpoint.

You can T in a line from the rod end of the cylinder. When you activate the "extend solenoid", also activitate this second solenoid, which is completely vented to atmosphere. When you want to pressurize the rod end of the cylinder to retract, close this solenoid so that the pressurized air on the rod end of the cylinder will cause it to retract.

The other option is to just let the rod end vent. You will get a very fast extension, When you release the pressure after firing, then small bungee cords can full the cylinder back. You can get these little cords at most hardware stores (they are like 1/8" diameter and 6"long).

I am guessing when you did your first testing, you did not have a closed system, so the air could easily exit the cylinder when you extended it.

[spazdemon548]

As mentioned above, the easiest solution is to transfer one or two of your accumulators to your 60 psi side. When doing this, try to keep this accumulator as close to the cylinder and solenoid as possible as to decrease your tubing runs. Tubing length does not have as large of an effect on the velocity as the tubing's cross-sectional area will, but it still makes a difference. You may also want to try doubling up on solenoids. I remember seeing a few teams do this last year.

Also, we have found that putting some light oil on the cylinder will help tremendously.

Hopefully you'll find something to work.