We are trying to cool a falcon motor, and don’t want to constantly blow air into it as out compressor would then never turn off and we would never be able to store pressure before the match. We are wondering if we can essentially suck air through the motor to cool it and then send that air into the compressor to then go to the rest of the robot. IF this isn’t advised, then we will probably just switch to using a solenoid to send air when the motor gets over a certain temp.
The intended use case is to plumb the exhaust port from your manifold into your motors. This way, air is pushed through whenever you actuate a pneumatic device.
I would go with the solenoid option. I’m not sure there are any compressors with an intake you could even hook up to, but even if there was you 1) don’t want to run pre-heated air into your compressor as that will make your compressor run even hotter which is bad for the lifespan of the compressor, and 2) you will have much less flow on the intake vs using air compressed to 60 psi. You may be able to plumb the exhaust of your cylinder control solenoids to vent through your falcons to save some air that way.
2 Likes
So we do have a compressor that has an intake. I believe it is the viair 92c. Are you saying the air would be preheated cause it goes through the motor ? because if it is constantly getting room temp air into the motor, will it even get hot? We are going to do some tests tomorrow.
Yes, that’s what Zach’s saying, at least to my understanding. The motor would still get hot as the compressor isn’t constantly running. Also, even if the motor didn’t get hot, it would still be adding heat to the air that went through the motor, making the compressor hotter. Room temp air heated, even a little, by a motor will be hotter than room temp air not heated. Those compressors do get very hot already.
2 Likes
Yup, basically what Eliot said. Even if you had enough cooling to keep the motor at room temperature, that means the heat is going into the air instead, and then into your compressor. And you will not have enough flow from that compressor to keep even one motor under moderate use at room temperature.
Some napkin math: Consider a moderate use Falcon pulling 20A @ 12V. According to the published data, this motor would be running about 5900 RPM with 0.34 NM of torque. That is 240 W input power and 210 W output power, so you need to remove the remaining 30W of heat to maintain a given temperature. If you want to keep the temperature at 44 C at a room temp of 20 C, regular air with a heat capacity of 700 J per kg per degree C and a max flow rate of 1.03 CFM can only remove about 9 W in the best case. And almost all of the assumptions made here work against you, lowering the amount of heat removed: the flow rate decreases as the compressor builds pressure, the extra restriction on the input flow will further decrease flow rate, the compressor is only rated for a 9% duty cycle and regardless will not be running at all times, and it is unlikely the air will actually achieve the full temperature delta in the short time it is in contact with the motor.
2 Likes