What is a denso window motor?

[Team2441]

Hey, guys, a really new and fresh team here, and we're not quite sure what a denso window motor is, or does, exactly. If someone could give us the lowdown on what it is, what it's capable of doing, and what it can be used for, we'd surely appreciate it. Thanks! :yikes:

-Team 2441

[MrForbes]

It is a power window motor for a car, it has a nice heavy duty motor attached to a worm drive reduction setup. It can actuate a medium sized mechanism, kind of slowly. And it can keep it in place after you turn off the motor, and it won't kill the motor if the mechanism jams or stops and you keep applying power to the motor.

usually they are run by a Spike relay, and run full speed either direction, but you could connect it to a Victor speed controller and run it however fast you want to forward or back (up to the maximum speed it will go).

It's a bit fun connecting it to a mechanism, you probably would use that funky black round thing that came in the kit and fits over the funky gear looking thing on the motor, which is the output shaft..

[lynca]

I see the fisher price motor used in Spool (winch) applications , Would it be possible to use the Denso motor as a Winch Motor.

I have a hunch that the anti-backdrive worm gear will make reeling the spool quite difficult (without motor power).

[MrForbes]

Yes, a window motor would work well for a winch. You will have to go to some trouble to figure out how to make the spool, and attach it to the motor gear adapter, and support it in bearings or bushings....

also you'll need to figure out the maximum load on the cable, and design the spool so it is the correct diameter to translate the available torque of the motor into force pulling the cable. And remember to derate the torque of the motor, that is, set it up so that you are only using about 20% of the "stall torque" at maximum loading.

Example:

for a motor rated at 10 N-m stall torque, you would design it to need a maximum of 2 N-m.

Let's say your mechanism needs a force on the actuating cable of 50 N to raise the arm. The available torque is 2 N-m, so your spool radius would be 2/50 = 0.04 m

so the spool diameter would be 0.08 m (that's about 3 inches, right?)

edit:
also you can use the speed of the motor to figure out the rate at which the winch pulls in the cable. If the motor is rated at 85 rpm at no load, it might turn at about 80% of that speed with a 20% load on it. So, you'll get about 68 rpm.

With a spool with a diameter of 0.08m, you will pull in 0.08 x pi meters of cable per revolution. That's .25 meters/revolution, and 68/60 x .25 = 0.28 meters per second (about 1 foot per second).

[Elgin Clock]

Under load the window motor is kind of useful... up until a certain point.

Basically it has a safety feature that shut's itslf off when it gets too hot. This is called a thermal protective device.

The actual application of a window motor, is to crank up a power window.

Since there is no switch to shut it off if you keep holding the button down to put the window up, what (I'm told) the motor does is have that safety built in and power itself off when it overloads itself when the window hits the top of the frame.
(Does someone want to verify that for me... I'm getting this info second hand, and while it makes sense, I don't know if it's 100% accurate)

Basiallly in the end, just be careful what kind of loads you put it under.. and test with the motor a lot before using it for a final application on your robot.

It's good to drive some smaller applications, but unreliable under a heavy load as far as I'm concerned from our experience with them in the past.

[lynca]

So i compared your calculations with a Fisher Price, to get approximately the same dimension of spool (3") lifting 50N , The torque ratio goes down considerably to 4% instead of 20%.

http://lyncas.googlepages.com/SpoolFP.PNG
It seems safer to run at a smaller percentage of the load torque to reduce current consumption. However, I am bit worried of running the fisher price close to stall to keep an elevator lift stable at a high position compared to having a window motor.