Electros without solenoids

[ScatterPlot]

I was just thinking... With a small enough pneumatic valve (something on the order of a hAIR or the PTP thing) or more probably a custom made one, could a paintball gun be designed that used a piezo to activate the valve? I dunno, I'm gonna go do a little research and post back later.
Discuss.

[ScatterPlot]

OK I did a smidge of checking some stuff...
Looks like these peizos only moove super teeny amounts (at least that's what the sound ones do anyway). Others I think might be able to be built that move some more. Maybe a shaft that will lengthen and get narrower with current? I dunno. Someone who knows about this crap help me out a little.

[cybershark]

Nitinol wire?

Perhaps instead of piezo-electrics you should look to something like nitinol wire. It contracts very quickly when electricity is applied, and it is the base material in a lot of robotic "muscles." I've played a little with the stuff, and I'm thinking you'd be hard pressed to get very high cycle rates out of it, but it can be used to very efficiently and repeatedly cycle. I just did a little googling though and found some references to cycle rates in the Khz, but have no references to the length of these cycles, or the amount of force they can constrict with.

I've also found references to Flexinol, but know nothing of it's uses. It is referred to as a better choice for actuators though on one page. This may be a better way to get the mechancial motion out of the electronics.

Oh, and Piezos can get longer travel if you stack several units, but I still believe it'll be far too short and weak to activate even the lightest valves.

[cybershark]

followup...

http://www.imagesco.com/catalog/nitinol/

2nd item from the bottom of the page....

now I'm liking this idea...

[ScatterPlot]

I wasn't sure about the "stroke length" of piezos (activation length or whatever). I was thinking maybe make the valve designed around a piezo, not use one to actuate a valve. What I was thinking of is maybe like a 1/4" diameter piezo rod fit inside an o-ring or something, then when it activates it gets longer and I would guess gets thinner in diameter, but then again I know nothing about piezos. That wire stuff is cool, gonna have to bookmark that site

[ocelot213]

if you wanted to make the piezo element actuate a valve perhaps a true roller trigger is possible...

[ScatterPlot]

^^^???

[Chronobreak]

im confued a bit but if the cycle time is 1 second on then 3.5 seconds off it would have no practical use....

[ScatterPlot]

I think it was meant to be an example, not something to actually use.

[cybershark]

indeed just an example

the idea being that a product exists that accomplishes atleast some of the desired goals. It uses an electrically driven system lacking any sort of solenoid to manipulate a pneumatic valve. Perhaps someone can study the efficiency of this valve as compared to a solenoid version and figure out whether further study is warranted. I'm worried myself that the Nitinol/Flexinol wire solutions will prove to devour batteries about as much as a solenoid. Ofcourse that's only if it can be brought up to cycle speeds in the first place

[RazorMonkey]

Number of cycles possible doesn't really matter as long as it's not EXTREMELY low... As long as you can get ~2000, it wouldn't be that bad, considering how amazingly cheap this stuff is Also, the NanoMuscle shows quite some potential in this case

EDIT:

I did a little bit of research... When not pushed to the absolute limit, Nitinol should last for millions of cycles. The cycling rate leaves a lot to be desired though... I'm thinking that the cycling rate might be increased by a heatsink of some sort...

[cybershark]

We've got the heatsink

if it's in a high flow area and mounted with a good thermal bond to the parts of the valve that it's actuating then it should do well at being self cooled. As long as the design is CO2 tolerant you may even be able to get faster speed out of going liquid. It could quench the wire quite readily, and if carefully dosed out in tiny increments you may be able to get efficiency quite high. As you cycled the gun faster it would probably actually perform better do to the chill effect it would generate. First off we'll have to see if significant strength and speed can be generated even for a slow speed. I'm tempted to get some of this stuff and try, but with my current goal being to acquire a mill I'm left a little cashless.

[RazorMonkey]

I completely forgot about CO2... That could DEFINITELY speed the cooling... lol I'm probably going to experiment some with this stuff, tell you how it goes...

[jamescell]

hmmm interesting stuff you are exploring here.

[cybershark]

sadly...

I'm guessing that to get the cycle rates high enough you'll have to be cooling the stuff so rapidly that it'll start getting brittle and giving out, but this could use some investigation. I've emailed a few places, but not recieved any answers about high cycle rates, or about possible performance boosts due to active cooling from liquid CO2