Is the CIM COOLER Good for use?

[nuggetsyl]

Cims do get hot and we have made heat sinks for team 25 and use them on the cims. Imo 80% of the teams do not understand how this game will played. This is not 2012 there is no safe zone. Imo this is the second coming of 2003. If you are a defensive robot and have the weight get some heat sinks.

[yash101]

They aren't too heavy either. I beclieve they are under a pound, so just use them on some high-strain parts, like the drivetrain.

[Gadeer Zbedat]

I'm really thankful for youre replies guys
Good luck in competition and have great building season \
Team 1946

[Vaude]

The coach of my team actually owns Next Gen Robots, the company that owns the CIM coolers, which came in the KOP.

To demonstrate, he did a 3 minute test of CIMs under no load, and you can see they make a huge difference. once you think about what kind of load your teams may be putting on these motors, you'll see they are well worth the additional weight.

www.youtube.com/watch?v=O-A6PXVUmW0

I can direct questions you may have to him, when my team meets tomorrow.

[RobotDoktor]

It can depend on your usage. Drive motors may not necessarily need it except during extended use or very high load. Our team's 2013 bot used a CIM to power a flywheel based shooter, which did get so hot in a demonstration/practice period we had to stop using it to avoid damage (oh, by the way, burning CIM is a bad smell). Any CIM that is under near constant use, especially on a PID, can definitely benefit from this. As to the overall effectiveness, it may not be as good as active cooling, but is simpler. The shell of the CIM is aluminum, so when the motor is hot enough it will conduct heat. Without some sort of thermal paste to aid the conduction between the CIM and the heatsink may not be totally efficient.

[roystur44]

The Banebot motors in a start stop high load conditions can get smoking hot. I've seen the power wires get red hot and melt the covering off. Wonder if there will be any heat sinks made for them???

[Vaude]

In continuation with my previous reply, my coach put the data from the video, which proves the effectiveness of the CIM coolers Here

After many requests, he also made a chart which lays out the temperatures Here (Select the second image, linking to the image itself resulted in a rather small image).

I am currently at my team meeting, so let me know if you have any questions!

[NextGenRobots]

Here's a snapshot of FRC TEAM 4283 with triple motor Gearboxes and Full 360 CIM COOLER configuration!



More shots of their build and Week 0 competition can be found at https://www.facebook.com/GranvilleRobotics. Thank you TEAM 1038 Lakota Robotics for hosting this past weekend in Cincinnati.

-Dan

[ausinhanks]

we are looking for more of these sim coolers and i was wondering if anyone knew where to buy them thanks

[Robo Hamsters]

Originally Posted by ausinhanks

we are looking for more of these sim coolers and i was wondering if anyone knew where to buy them thanks

http://store.nextgenrobots.com/product/cim-cooler-360

[MrForbes]

We switched to the little Viair compressor this year, and like many other teams added a big fan to keep it cool. Since the compressor is in the middle of our robot, between the drive motors, it also happens to keep the outside of the drive motors cool. No heat sink required.

Your mileage may vary.

[Jarren Harkema]

Originally Posted by MrForbes

We switched to the little Viair compressor this year, and like many other teams added a big fan to keep it cool. Since the compressor is in the middle of our robot, between the drive motors, it also happens to keep the outside of the drive motors cool. No heat sink required.

Your mileage may vary.

Same sort of set up for us as well. We are using a server fan which blow air across the compressor and cims on the left side. This worked so well we mounted a second fan on the the other side to keep the right coms cool.

[Nathan Streeter]

As has been mentioned by Andrew Palardy and others, a heat sink will probably have relatively little impact on the motor winding temperature over the course of a 2-3 minute match... See Richard Wallace's data for evidence regarding that (note how, during the test, the motor case temp only rises by about 5-10degC).

Where I do think a heat sink would make a difference - and I think it would - is when you put the usage in the context of practice, elim matches, or short match-turn-around (i.e. districts or off-season), etc. The internals of the motor can't be cooled below the CIM case temperature... so as the external motor housing climbs to higher temperatures, so also do the minimum and working internal temps (since under same power output conditions, the same deltaT will be maintained from motor windings to CIM case).*

So, I definitely recommend that teams consider how to cool their CIMs! I know I'd like to work out a way to put a heat sink solution on our robot!

I haven't used the CIM COOLERS but they look like a neat solution... I do have a few comments about them though:

-The linked video test is neat, but running at free speed is fairly low heat output (32W)... At max power they dissipate 477W, and at stall they dissipate a mind-blowing 1596W**! At only 32W, simply adding aluminum to the case to hold more heat for a given temp increase would have a beneficial impact.

-Heat sinks rely on air taking the heat away... hence the fins. Without a fan (forced convection), it relies simply on the air moving around... which is driven by the fact that air becomes lighter when it gets hotter. In the test the fins are vertical (ideal), while on almost all robots they are at all angles (vertical, horizontal, upside-down)... this means its effectiveness will be significantly lower when mounted horizontally, particularly in a cramped robot.

- If teams use the heat sinks, they should definitely apply thermal paste (I've had experience with silicone grease and other gap fillers... i.e. http://www.bergquistcompany.com/ther...roperties.htm). Interfaces are tremendous thermal insulators... applying a little thermal paste and then bolting the heat sinks together firmly enough so that paste squeezes out will help tremendously. With many Watts being dumped through that interface, you could have a huge thermal rise just in the interface (let alone the motor internals). I wouldn't be surprised if using the CIM COOLER with no thermal compound gives little or no benefit. If you do use a thermal paste, I highly recommend the blue stuff from Bergquist... compared to grease it's extremely easy to cleanup!

So, I would recommend investigating a CIM-cooling solution... but putting some big muffin fans on there to run while the robot's on or off may go about as far (note, the robot's usually on the cart far more than it is powered on). You'll likely want fans somewhere to force the air around, rather than relying on free convection.

*If you're interested in a tidbit about heat transfer... it works the same way electricity does. In electricity, a Voltage drop (i.e. deltaV between two battery terminals) drives/pushes electrical current (I) to move against electrical resistance (R). Similarly, a Temperature drop (i.e. deltaT between CIM internal and CIM case, then between CIM case and ambient) drives heat to move against thermal resistance.

** Note, 1596W is nearly as much as an oven puts out, and well over that of a microwave! Now that certainly motivates me to cool my CIMs and avoid stalling them!