Compressor question

#21
The treadmill motor should work for a prototype but what you should be looking for is probably a lot different than what you are looking for. It is very possible to build a quiet, low volume, high pressure air compessor. Generally smaller compressors make a lot of noise from two places. The intake and the non-lubricated drive system. For low volume applications you may be able to get away from a piston compressor and go to a diaphragm
Setup. A small 120 motor would have no issues and it would really reduce the price
 
#22
From my understanding, treadmill motors are DC. For DC motors if you vary the voltage, you vary the torque and speed the motor runs at. For an AC motor, you must vary the frequency to vary the speed/torque of the motor. My suggestion, if you're doing a reciprocating compressor, is to get a high speed / low torque AC motor (these tend to be the cheapest kind) and gear it down to the rotation speed / torque you desire. You can design the gear train yourself, or there are gearboxes out there pre-made for this type of thing, its just finding one to match your requirements.

Actually, what about a refrigerator compressor. I've seen these used before as stand alone, low volume compressors. They are quiet, small, and can be wired to turn on and off to maintain a set pressure just like a regular air compressor, just be sure to use an unloader valve in the setup. The compressor does need to be oiled though(setup is similar to using an old A/C pump for an onboard air system) and depending on the air cleanliness requirement , that may be a problem. Just a thought.


--Justin
 
#23
One thing thats hasnt been mentioned. The majority of the noise you hear from a traditional compressor does not come from the electric motor but rather the "pump" part of the compressor. That traditional thud thud thud thud thud you hear is the pistons moving up and down performing the actual "compressing" of the air.
 
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