I posted directly via the contact form on the blog, not sure if it made it through.
I'm way out of my lane even commenting on this, but maybe you can dramatically simplify the air delivery side of this design, if you're willing to under-engineer. A single air chamber with an inlet (blower in) and two outlets (patient out and return out). Low rpm motor slow rotating a sealed disc with holes in it balancing outflow between feed-to-patient and return. Put a blowoff mechanism inline around the flow meter. If the capacity is there and there's such a thing as a common or global delivery 'frequency', maybe it could support more than one person.
Again, I might as well be from another planet in terms of knowledge in this domain. I'm just confused at the apparent complexity around the servo, linkage, and waste-gating. I DO get that delivery can be tailored nearly entirely in software with this design. That's cool.
Not by any means an expert here either, but my impression is that, to call something a “ventilator” in a medical context, it has to have a software-controlled rate of flow. “Ventilator” is to “air pump” as “CNC router” is to “regular router.” It needs to be integrated as part of a control system, feeding out forced air-pressure (thrust?) data, and getting fed back a PWM control signal. (Sort of like a CPU fan, but with air pressure in place of on-die temperature.)
Keep in mind, the use of these things is that you hook this up to a patient and then leave them in a room while you go handle other emergencies. It needs to tell you if it’s having a problem (through hookups to monitoring equipment.)
I think it also needs to not try to force air into a blocked airway (i.e. to blow open the patient’s larynx the moment they try to swallow), and/or needs to let up on the air pressure in a sinusoid pattern so the patient can exhale—though I might be wrong about either/both of those, given that they’re not really problems doctors encounter with hand-pumped ventilation. But either of those, in combination with the flywheel-like momentum of a big blower fan, would explain the waste gate.
I'm way out of my lane even commenting on this, but maybe you can dramatically simplify the air delivery side of this design, if you're willing to under-engineer. A single air chamber with an inlet (blower in) and two outlets (patient out and return out). Low rpm motor slow rotating a sealed disc with holes in it balancing outflow between feed-to-patient and return. Put a blowoff mechanism inline around the flow meter. If the capacity is there and there's such a thing as a common or global delivery 'frequency', maybe it could support more than one person.
Again, I might as well be from another planet in terms of knowledge in this domain. I'm just confused at the apparent complexity around the servo, linkage, and waste-gating. I DO get that delivery can be tailored nearly entirely in software with this design. That's cool.