Circuit for Misting/Cooling my Currie

[dozentrio]

I just bought a 36 volt controller for my 1018 Unite motor. I haven't drilled my holes yet, or run my plumbing, but of course I will have to if I don't want to cook my motor.

I want to give my motor extra-special treatment, so I also want to add a spray misting system, which will spray a fine mist of distilled water if my motor heats up past some threshold. Here is where I need a little bit of help.

I'd like to put a thermistor or two (for the added redundancy, perhaps, in case one fails or gives a bad reading) inside the motor casing close to the windings. I want to use a simple analog circuit to control my misting system and blower, based on the temperature inside the casing. I'd also like a potentiometer so I can adjust my "threshold" values for the blower and misting-pump.

If the temperature exceeds threshold 1 (30 deg. C or so), the blower starts, [strikeout]and blows proportionally to temperature[/strikeout] (unnessarily complex). If the temperature exceeds threshold 2 (adjustable by my potentiometer) the misting pump blows a burst of mist, maybe for 5 seconds or so. I don't want it to mist constantly because I think even a short burst of mist will cool the motor plenty. However, it will take a little while for the temperature to drop as a result (thermal inertia). At full "cooling power" I would like my mist sprayer to spray 5 seconds on, pause 10 seconds, and cycle like this. The time intervals don't have to be exact of course, but you get the idea.

Now I know capacitors can be used for the time delays, and zener diodes can be used to set my thresholds somehow, and maybe relays can be used to switch my blower and misting-pump on and off, but I lack the confidence to try to design the circuit myself. I've a limited understanding of such things, and have never done it before. So... can anyone help?

 

[Lock]

Not sure why you don't just have a motor properly sized for the mission? ...but anyway.
Can't say either whether misting is a way to go. Only thought was that you might add a feature that cools/mists for a while after the motor stops instead of stopping immediately when the motor stops.
tks
locK

 

[dozentrio]

Everyone asks me that-- why I didn't get a properly sized motor. I picked the wrong motor in my eagerness to get going I don't really have a good excuse, but there are a couple of reasons.

-I live in Ontario, and ebikes above 500 watts are illegal. At least I think so. You're probably more informed than I on this Lock
-I like the gearbox that comes with the my1018.
-I'm experimenting with a "quick-release" motor (and controller and batteries) idea, for people who want to be able to A) install this kit very easily B) put it on a different bike easily C) take it off the bike and into work, school, the house, etc. so it doesn't get stolen, and for easy charging. The my1018 is small and relatively light, and with my drivetrain idea would come off more quickly and easily than a bigger motor
-I am poor, and smaller = cheaper
-I'm a student, and I'm doing this partly to apply what I've learned, so the stuff really sinks in. Building a cooling system is fun!

 

[TylerDurden]

According to Reid, humidity is good for the brushes.

I'm not sure about a mist, though.

Perhaps a two speed fan? (high and super-high)

As for circuits, perhaps simple thermostatic switches (skip the R-C delays)... the key thing is temperature.

 

[Lock]

...in Ontario, and ebikes above 500 watts are illegal. At least I think so.

Correct

-I like the gearbox that comes with the my1018.

my1018? Rated 250W? I suspect you'll have more than heating problems trying to pump more watts through that baby... like, stripped gears... Others here are far more knowledgeable about tech than I...
My first scoot came w/350W approx. And almost immediately I swapped up to 450W... World of diff and the motor never gets hot to the touch.

Building a cooling system is fun!

If you look at it this way then you are good to go! G'Luck! Personally I value reliability right up there with safety and for reliability I always look for the least amount of parts and components.
locK

 

[dozentrio]

I ordered a 450 watt my1018. It looks the same as the 250 watt one. I am not sure what the difference is, I just hope there is one, and I'm not getting scammed I am a little concerned about the windings lifting if I try to run too much current/voltage. Someone mentioned they had that problem with a different motor... Or my magnets getting de-magnetized. Or some other hideous result from trying to run a motor past its rated values.

As for circuits, perhaps simple thermostatic switches (skip the R-C delays)... the key thing is temperature.

I looked into thermostatic switches. I did find some neat stuff from Cantherm, but the response time was a little low. It seems like they are meant to be pressed against a surface, whereas mine would be floating in the air near the rotor windings. There are some neat dual purpose ones that do current sensing and temperature sensing. If they go above rated value (and you wire them in series with your motor) it will just cut power when they trip. Max value was 22 amps though, and again, the response time is a little low.

I tried to draw out a circuit I think -should- work for controlling the fan/blower. I'm not sure about how to do the amplifying part though. I basically need to control my power going to the fan/blower from the voltage (0~5 volts) from here.


I've heard electrical people talk about op-amps and mosfets (my professors included) but never did quite get it. Can someone help me out?

 

[Lock]

Hey doz... did you try typing my1018 into the search field here? Lots of hits with subjects about overvolting and cooling eh?
lock

 

[JS Tyro]

mine would be floating in the air near the rotor windings.

Never put one part that isn't solidly secured next to another part that's moving. Unless, of course, you want it to fail. It should be secured in place with something to keep it where it belongs else when you ride over a bump, the thermistor and rotor will try to become one.

I say this in case you aren't using the term "floating" figuratively.

 

[michaelplogue]

They make something similar for controlling computer fans - might work in your application. These ones have a temperature range of 30 to 50°C:

http://www.frozencpu.com/search.htm...=5trErhpk&searchspec=NoiseMagic+ThemoControl+