Note: Obviously, this project is not anywhere near presenting to a doctor for consideration, and further development. Do not make this. Do not try this under any circumstances.
You only have to pump about a half-litre of air to save a human life. I realize that a lot of people are working on designs, but for every one of use messing with this, it puts more pressure on the corporate world to compete.
I messed around with this idea yesterday, and some, tonight. There are only concepts here. I am just moving stuff around, so go easy on me. I just need to step away from it and think more.
The device would be 3D printed in the 1st world, but perhaps it could be made of plywood in the 3rd world, so, I am going to try to keep it K.I.S.S. . Because I mean for it to be 3d printed, the largest part must be smaller than 200mm x 200mm x 180mm.
I want it designed so it can be 3D printed in sections, so a trashed print will only set you back no more than 25%, so it cannot be monolithic, BUT the parts need alignment surfaces and edges, so it cannot be assembled out of alignment. Perhaps there will be bolts and 3D printed pins, so there is no misalignment.
The idea is to make something rugged that would use as many ordinary materials as possible. Instead of using linear rails, I thought to use skateboard bearings because they are good, cheap, and plentiful.
Oddly, fasteners will be a problem. In the U.S. metric fasteners are rare. Elsewhere USCU/SAE are likely unobtainium.
Yes, I know I have the NEMA 23 motor interfering with the top. It needs a motor mount, too. The whole thing is going to have to be redrawn with gussets and holes to save filament. It will have to be triangulated and filleted.
The motor would likely be a stepper, but perhaps in poorer regions, the could use some other geared controllable motor.
I am not happy that there are sliding parts, but squashing some kind of bag with a rotating part tended to want to pinch it.
Perhaps the displacement could be adjusted by offsetting the eccentric or changing it out, but that is where a lever and bellows design was better. Perhaps the bottom plate could be movable. Doctors check the progress by reducing the volume, and see how people respond.
Perhaps a column of water could be used to eliminate overpressure, just the opposite that a vacuum lock works for pnumothorax chest tubes, which I spent a few weeks with : O