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Regulator/automatic metering system

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Regulator/automatic metering system

Unread postAuthor: saefroch » Mon Sep 20, 2010 2:59 pm

Today I was toying around with the idea of an automatic metering system for a hybrid, and eventually came up with this design. I do realize it's mostly an over-engineered regulator, but with a simple adjustment to the extension air spring, one should be able to re-calibrate it. As usual, the drawing is not exactly to scale, though I tried to get it close enough to make sense. Thoughts?

Image

EDIT: Explination:

The gas flows in the directions the arrows point. When the gas flows into the valve system, the piston begins to slide to the right, into the path of the air, beginning to shut the valve. As pressure increases, the piston creeps forward into the path of the flow because of the differences in area on either side. There is also an extension air spring on the back of the valve that restricts the shutting action, but once the o-rings get to the openings, air rushes in, the piston jerks forward and cuts off the flow, and the holding pin (presumable spring-loaded) slides in to prevent farting.
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Last edited by saefroch on Mon Sep 20, 2010 7:52 pm, edited 1 time in total.
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Unread postAuthor: Fnord » Mon Sep 20, 2010 3:24 pm

Something I made and never implemented when I was in ohio...

The slide is your meter volume. Input and output are interchangable.
To adjust the meter volume, turn the bolt.

Coincidentally, 1/2" copper and 1/8" sch40 steel work well for this design.
Put a spring against the green part(epoxy) if you want it to auto-recock.
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Unread postAuthor: saefroch » Mon Sep 20, 2010 4:26 pm

So does your design dump from the "fill" side to the "chamber" side automatically, or is it manually operated, and just meters a volume at whatever the "fill" pressure is?
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Unread postAuthor: POLAND_SPUD » Mon Sep 20, 2010 6:33 pm

@fnord
that's a 3 way valve, you know ? :wink:
Just use off the shelf parts...
All you need is a regulator + 3 way valve



Also, an air piloted 3 way can work as a sort of regulator. Have a look at this
Image
if you want to switch it you've got to send air signal to the pilot port. Of course, the air pilot port can be hooked up to almost anything.

If in normal position propane can flow through the valve to the chamber and from there to the air pilot port then you can use it to automatically cut off propane as soon as the right pressure is reached.

If you want to use it with propane then you probably need and air amplifier, which is basically just an air pilot attached to the 3way, but larger than the one you can see above. The larger the diameter the lower pressure you can use to switch the valve

Ohh I found a pic of a valve with it Image
They come in different sizes and shapes but they are all just air piloted 3 way valves
Clippard has them too
http://www.clippard.com/store/display_d ... p?sku=2010

I don't know how consistent would the method be but with an air amplifier I suspect that it should be fairly consistent.
Of course, you might as well just use a standalone reg to improve accuracy and use the air pilot just for automation.

Notice that you don't have to use a pressure switch, electronics and solenoid valves. You might as well use a fully pneumatic system based on air piloted valve.

What is more, you can use air piloted valve to provide timing. With a flow control valve attached to the port of the air pilot it will take some time before the signal is sent to the air pilot and the time the pilot switches the valve. You can use that if you want to build a time delay based volumetric metering system
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Unread postAuthor: saefroch » Mon Sep 20, 2010 7:44 pm

Okay I understand little bits of what you're trying to explain to me, but since I have no understanding of what's inside that "air piloted 3 way."

Are you saying you could put a pop-off onto one of the ports pilot the valve and cut the flow?

I think what I posted could be considered an "air piloted valve." I'm adding an explanation of how it's supposed to work for clarification.
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Unread postAuthor: POLAND_SPUD » Mon Sep 20, 2010 8:19 pm

Inside there is a piston. When you pressurise the thing the piston moves and switches the valve - that's all. It's like a miniature air cylinder - it converts pressure to motion.

yeah, it's that simple.

EDIT
:-D
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Unread postAuthor: Fnord » Tue Sep 21, 2010 8:48 am

saefroch:
Yes, my valve is manual, not full auto. IMO it would be easier to make a meter that operates using the hybrid's autobolt movement than one that just goes pop-pop-pop all by itself. An automatic meter may lead to timing problems if you're not careful.

You could just put a copper coil around the slide in my design; running current through it would cause it to act like a solenoid.
(you can put a regulator on my design also, but a reg is more prone to failure than the adjustable meter volume)
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Unread postAuthor: jackssmirkingrevenge » Tue Sep 21, 2010 9:06 am

*facepalm*

where have you been putting your fingers?
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Unread postAuthor: POLAND_SPUD » Tue Sep 21, 2010 9:40 am

You could just put a copper coil around the slide in my design; running current through it would cause it to act like a solenoid.
But you can buy a solenoid 3way valve for about 15-20$ and it does the same thing but better

An automatic meter may lead to timing problems if you're not carefu
Timing valves are used in places where you can't use electricity becasue it is too dangerous, for example in mines. AFAIK they work perfectly.

Timing valves are basically just an airpiloted valves with an inbuilt flow control valve.
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