I’d argue that quick-exhaust valves are flow control valves under R77-H, because what they do as a function is control flow. They divert the flow of air from one port to another. They are a commercially produced, readily available, pressure-rated component. Okay, maybe it isn’t what FIRST means by flow control (with the little knob to slow down the flow of air) but still, what’s the harm?
What’s the reasoning for ruling them illegal? Making quick-exhaust valves illegal completely invalidates SO many innovative designs, and limits students’ exploration of the physics concepts behind pneumatic systems.
What’s the history on the legality of these in years past?
Really hoping they reverse this ruling. Until then, we are out hundreds of dollars, and now redesigning our launcher…
That’s interesting… For a while, we were thinking of using them too. They are (what I would consider) a flow control valve.
We’ve put these on our robots for years. I may be remembering wrong, but I think something like that may have been given in the kit in years past.
What’s stopping you from getting a solenoid valve with a really high flow rate, then connecting it directly to the cylinder? Also, you’ll only need this valve on the retract side, so you could go with a spring/gravity return.
If you have used those valve anytime since 2008 (the year I started FIRST) you were not legal. I use pneumatics in my job, and quick exhaust valve (also called quick-dump) are extremely useful, but have never been FIRST legal. Believe me, there were many years that I wanted to use them!
They are not flow control valves. A flow control valve can restrict the flow, not re-direct it.
I’ve been disappointed too. There have been several prototypes that would have worked if the exhaust wasn’t restricted through the solenoid. I guess they want to “err on the side of caution” and ensure there is some dampening of the cylinder.
If y’all haven’t seen team 2073 cocking mechanism, take a look: Very clever catapult
I think there is a fitting that vents and prevents contamination at the same time. I wouldn’t leave a cylinder’s retraction port open to the particle-filled FRC world.
I’m wondering if there exists such a thing as a “quick exhaust fitting” If so, it would be a fitting, not a valve, and thus rendered legal for use. Anyone an expert of pneumatics manufacturer’s catalogs?
I’m curious to hear the answer as we have used a 90 degree fitting with no tubing to vent to atmosphere while using gravity to return the cylinder for the last two years. We used it on our ball pickup in 2012 and our climbing arms and disc dump in 2013. Both years we passed inspection at two districts and MSC.
Also, if you put the opening in the cylinder out of the way of a place where dirt and dust can accumulate, there is very little risk of pickup up any debris.
Another solution is dual solenoids, each one with one capped port, and one side connected to the cylinder. This lets you push it back down, and then vent to atmosphere.
Never say never. A geared down continuous rotation servo would probably do it. But but not sure if you’d have needed position control w/out adding POT.
There is no rule which states that the open ports of a cylinder must be attached to the solenoid, which means that there is no reason venting directly to the atmosphere is illegal.
If it were made illegal via a new rule, I’d be pretty upset. We are working on a design that uses pneumatics and hasn’t been seen in FIRST (or at least in the many designs I’ve seen or studied from 2008, 2010, or 2014). It’s pretty simple, but relies on the pressure venting directly to the atmosphere. We could possibly overcome a ruling, but only by moving to more expensive solenoid valves.
Which is why I can’t understand why quick exhaust valves are illegal. Perhaps it is the difference in venting near-atmospheric pressure to atmosphere, as opposed to venting 60 PSI to atmosphere? Still, I don’t see the danger in it.
I view the new solenoid valve rule as a positive step. My impression is the GDC is keeping the pneumatics restricted to keep the robots safe & to simplify the inspection process.
This was done in 2010. No comment on if it would be legal in 2014
Posted by 2010FRC0476 at 01/25/2010 10:52:27 am
Can we use plug valves, Parker model # PV609-2 as allowed in Rule R72, instead of
solenoids to activate and exhaust pneumatic cylinders? We would rotate the plug valves using
pneumatic 90-degree actuators and a custom-made bracket between the pneumatic actuator
and the plug valve handle. Or we would turn the plug valves using HS322-HD servos or the
Denso window motors.
Re: Plug Valves Instead of Solenoids
Posted by GDC at 01/28/2010 12:03:45 am
There is no rule that would prohibit this.
A geared down continuous rotation servo would probably do it. But but not sure if you’d have needed position control w/out adding POT.