compressed gasses

[terc04]

Hi all. I am looking for some advise/expertise in the area of compressed gasses. Namely, those used in paintball and your shifting systems. I
have two basic questions. Is there any way to be able to run a CO2 tank and regulator on it's side (laid down)? If not, what happens to your
valves, regulator, etc? The second question is, what about using N2 or HPA? My fear of these is that since they are not a liquid they will lose
a finite pressure for each shift and cause us to have to adjust our regulator after so many hours of usage. I am just looking for some info
from those with more experience than anyone here.
Thanks in advance,

Tim
Mizzou Racing

[terc04]

Hi all. I am looking for some advise/expertise in the area of compressed gasses. Namely, those used in paintball and your shifting systems. I
have two basic questions. Is there any way to be able to run a CO2 tank and regulator on it's side (laid down)? If not, what happens to your
valves, regulator, etc? The second question is, what about using N2 or HPA? My fear of these is that since they are not a liquid they will lose
a finite pressure for each shift and cause us to have to adjust our regulator after so many hours of usage. I am just looking for some info
from those with more experience than anyone here.
Thanks in advance,

Tim
Mizzou Racing

[Duke of URL]

My opionion:

Don't use fluid power unless you absolutely have to.
That includes hydraulics and pneumatics.

Try to find an electromechanical solution first.

Check out the Solenoid shifter forum.

[sticks]

Frankly, I would worry significantly about the drop in pressure of the HPA or N2 in comparison to C02, as they will both drop in roughly the same degree. With the advent of truly high pressure tanks though (4500psi and greater), I think the advantage in terms of consistent air pressure and endurance has to go to HPA. However, the the actuating pressures for something like a gear shift, the operating pressure should always be sufficient. The only exception in regard to competition might be the endurance event. In oder to be relatively secure in not sucking liquid C)2 from the tank while lying horizontally, an anti-siphon tube inside the tank and attached to the valve would be recommended. While not foolproof, it would significantly lessen the odds. I would have to agree that the use of liquid is theoretically less ideal then electromechanical, but with the specs I've seen on most electronic actuators, I would be slightly swayed toward liquids as well. Mechanically I am a big fan of the butterfly shifting design, but thats a bio/mechanical solution, so probably useless to your design plans.

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Duke of URL:
My opionion:

Don't use fluid power unless you absolutely have to.
That includes hydraulics and pneumatics.
<HR></BLOCKQUOTE>

So, what is your reasoning for this opinion? I don't think you will sway anyone by simply your opinion, but if there are good reasons to stay away from this technology lets hear them.

-Charlie Ping
Auburn University FSAE 1999-present

[Richard Lewis]

Personally I'd take a hydraulic clutch over a cable one anyday...

-------------------------
UVIC Formula SAE Team

http://fsae.uvic.ca

[Brent Howard]

I am not on the shifter design team for calgary, but my understanding of the reasoning agains the pnumatic system is that the loss of pressure per shift is fairly high and the wall thickness of the container to hold enough gas at a high enough pressure would be fairly high....resulting in a heavy syatem. In drag racing i was told that they fill teh chassis with compressed air, howerver, they are only doing one short run, not long laps. The reason behind not using hydralic systems is that the weight again is higher than an electromechanical system. Also, you have the potential for leaks. With and electromechanical system the weight is light, and also easy to make a paddle. Think of how hard it is to press the brake pedal with your hand and think of doing something simaler everytime you need to shift. With an electricl stsem all you have to do is change the circut.

Brent

www.ucalgary.ca/fsae

[Richard Lewis]

I totally disagree about the weight of shifting system being a drawback for electro-pneumatic. I've not heard of anyone with an elecro-mechanical system that found push-pull solonoids of a reasonable weight. You're looking at (don't quote me) in the area of 8lbs just for the solonoid if I remember correctly.

I believe our electro-pneumatic system as implemented last year weighed less than 8lbs, including bottle, fittings, lines, solonoids, cylinder, etc.

I'm sure a fully mechanical system can be made for less weight. My question is, do you really want to take one hand off the wheel? [img]/infopop/emoticons/icon_smile.gif[/img]

-------------------------
UVIC Formula SAE Team

http://fsae.uvic.ca

[terc04]

Here is what I have come up with.

An old car of ours (1997 vintage) has an electromechanical shifter. Total system weight is 4.97 lb. The system worked well, but was hard on the F2's shift forks. Some creative EE thinking fixed the problem.

Our current cars (1998 - 2002) use a mechanical lever and either a push-pull cable or a system of rods and bellcranks. Most weigh in at under 2 lbs. Only a few of our drivers understand how to shift properly so we see a lot of missed shifts and bent or broken shifters.

Now for the new car. We have selected a tank, solenoid valves, cylinder, lines and fittings that has managed to keep the total weight at 2.62 lbs. We will also be able to integrate nicely with our ECU to give us a few handy features that will remain secret for the time being. The entire system is also well hidden on the car. Reliability is the only question still unanswered.

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by terc04:
Now for the new car. We have selected a tank, solenoid valves, cylinder, lines and fittings that has managed to keep the total weight at 2.62 lbs.

Reliability is the only question still unanswered.<HR></BLOCKQUOTE>

Hmmm... I'd say longevity is another question. Does that weight include the weight of the gas? And if so, how did you decide how much you'd need for the endurance event?

-Charlie Ping
Auburn University FSAE 1999-present