Cooling the Drill Motors

[Kevin A]

Hello,

Im on team 481 and we tested our drivetrain for 5 - 10 minutes on Wednesday and noticed the drill motors were really hot, and this is driving in low gear without pushing, not fully weighted down. So we've decided to use those little muffan fans to cool the motors, and we are wondering whether to blow air over them or pull air past them.

TIA,
Kevin Antaki
Team 481

[Frank(Aflak)]

I think blowing air past them would be more efficient . . . There is more air movement on the pushing side of a fan because it is more focused. Move air faster, and the air around the motor will stay nearer to room temp, sucking heat faster than it would if it was a shade warmer, as it would be drawing air past because the air in question would be in contact with the motor longer because it isn't moving as fast.

Of course, you have five muffin fans, mor max cooling I would recommend doing both - one sucking and one blowing.

[Kevin A]

Thanks for the advice, i will talk to my teacher about putting 2 fans on each motor, and the other thing is we are also going to be using the chippy's for drive motors, so they may be deserving of some fans too!

Kevin Antaki

[Not2B]

Here's a tip from the Lightning crew....

The exaust from the air pistons can be directed to the motor, via a piece of air tubing.

A few words of note:
-This is only gravy on top of a good air/temp management system
-Air gets hot when compressed, but I am assuming that the storage tanks have a chance to cool down somewhat.
-This worked for us in our rookie year when we were over heating the drill motors. Not many people noticed, but Ziff1.0 would move his lifters up and down like crazy in an attempt to cool off the motors.
-Also remember - hot air moves upward. Don't try to blow air down... just working against natural convection.

Wow.... first time my work in the climate control biz has helped with FIRST...

[Adam Krajewski]

If you think about it, 5-10 minutes of moving a 100 lbs+ robot is a lot to expect for a motor from a cordless drill. Also, it goes far beyond the length of any match you'll be in.

Back in '99, we had all sorts of problems overheating motors during the 2 minute matches (so much, in fact, we could change out toasted motors and speed controllers in under 2 minutes), so in '00 we designed our aluminum motor mounts to clamp around the body of the motors. This worked very due the ability of aluminum to sink away a great deal of heat, not only to the clamp, but to the rest of our frame. Just ask anyone who welds aluminum and they'll tell you the same. It’s also the same reason computer heatsinks are made primarily from aluminum. They worked even better when combined with active fan cooling, but were far less effective without the 'heatsink' mounts.

My advice to you is to design an aluminum clamp that connects to the body of your motors as smoothly and tightly as possible (for the best heat transfer) and then to your frame and if that isn't enough, fan cool the clamps/motors.

In terms of computer heatsinks, blowing across the heatsink almost always yields better results than sucking air over them. The opposite only seems to be true for very large heatsinks that are designed to suck air via special ducting (name anything produced by Alpha Co. Ltd.).

Adam

[Al Skierkiewicz]

All teams should be aware of the cooling issues with motors. On the new drill motors (bare bones) you will notice that the end opposite the brushes and fan, has two slots cut in it. The fan is a centrifugal unit so it throws air out from the edge while sucking in at the center. With that said it is easy to see how air is drawn in at one end, passes through the motor and out the fan. Disturb any of these three mechanisms and high heat will result. Don't block the intake, don't block the brush assy, and run the motors at sufficient RPM to let the fans do their job.