Cool Diaphragm-Engine

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Orngrimm
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Cool Diaphragm-Engine

Post by Orngrimm »


Not my video not idea. But i think it is super cool and well explained.
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Downunder35m
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Re: Cool Diaphragm-Engine

Post by Downunder35m »

Reminds me of the putt-putt engines....


But what you posted in the video I have seen as a commercial product to pump syrup.
Coca Cola uses air driven diaphragm pumps basically operationg like the one in your video.
Just without the drive shaft as a second diaphragm just pumps the syrup.
However, in their design there is no hole in the diaphragm and complicated pin system either.
A tiny membrane flexes in the chamber and operates a vale for the vent channel.
Works a bit like these reverse cycle valves in your aircon, a fully sealed system. ;)

I see the possible options for the above engine in low speed applications.
The loss of air is minimal and despite the piston drive efficiency is not that bad either considering it is just compressed air.
What i fail to undestand is the gear approach in this configuration.
A proper crank would provide the required balance in the system and allow for a 90° change in the drive rotation.
The engine would be bulkier but with a much higher efficiency.
The valve system could be simplified by utilising the same approach as in paint ball or gel blast guns.
Meaning, instead of using a double valve that is driven by the piston:
The valve travels through the pressure and expansion chamber.
Check the preview pic of the above video and take away the ball first.
Now you have the two chambers with the seal rings.
The valve is a hllow shaft with two holes and a channel between them.
The top hole, when the piston is all the way up, allows the pressurised air to pass through to the second hole, exiting into the pressure chamber.
When the piston travels down the valve shaft seals the top ring - it has to extend much further out than the wire pin!
But then the lower hole travels into the chamber with the diaphragm while the top hole opens the connection to the pressure chamber - POP!
And well, as you might have guessed already, if you modif the hollow shaft a bit more with another slot and add another seal with exit port you won't even need a hole in the diaphragm anymore....
Only downside is that you need to find the right hole and channel sizes for the airflow and volumes you plan to use.
But if you use these CO2 capsules for tire inflation with their simple valve I guess you could get even longer flight times than what you get from a soda bottle - despite the extra weight.

Interesting concept that I might have to try out one day if I find the time....
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liquidhandwash
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Re: Cool Diaphragm-Engine

Post by liquidhandwash »

that a great little engine design thanks for posting it
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Orngrimm
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Re: Cool Diaphragm-Engine

Post by Orngrimm »

The idea behind the gear is (As he says in the video) to have the option of a gearing if needed.
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Downunder35m
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Re: Cool Diaphragm-Engine

Post by Downunder35m »

I understand that.
But having the gear directly on the piston instead of a crankshaft creates a lot of unwanted problems, not just a bad balance.
With the moving mass of the piston compensated the output is much smoother and a gear on the crankshaft would still provide the required reduction or re-direction.
Just print a simple crank mechanism with direct gear and one with a proper crankshaft.
You will feel the difference when cranking it by hand already.
despite the extra parts the friction will be less as well because the forces are going in a striaght line so to speak.

If using a simple and direct gear instead of a crackshaft would work good enough then these small RC comustion engines would not bother with the extra parts and added gearbox ;)
But I am not the designer of the engine and have to assume the guy doing it know why he is using this approach.
Might be just weight or the complexity of creating a matching crankshaft.....
Exploring the works of the old inventors, mixng them up with a modern touch.
To tinker and create means to be alive.
Bringing the long lost back means history comes alive again.
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Orngrimm
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Re: Cool Diaphragm-Engine

Post by Orngrimm »

It was a proof of concept. More for the piston assembly than for the gearing afterwards as I understand...
No optimisation there yet..
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Downunder35m
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Re: Cool Diaphragm-Engine

Post by Downunder35m »

Well, then I sit back for a while and hope he will provide a nice update soon :)
I like seeing people doing things differently and getting hooked on a problem with the will to solve it.
Exploring the works of the old inventors, mixng them up with a modern touch.
To tinker and create means to be alive.
Bringing the long lost back means history comes alive again.
liquidhandwash
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Re: Cool Diaphragm-Engine

Post by liquidhandwash »

He has an updated engine no more gears, I want to see him drop some dry ice in the bottle.
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