Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: Billy on May 25, 2011, 09:56:20 PM
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Any of you have experience with windshield wiper motors? Are the frames/case of the motor isolated from the both motor leads?
I'd consider using a couple of them in a home project but both would be on H-Bridges so the frames would have to float relative to the motors windings, or I would have to use a non-metallic frame(which I don't want to do).
Thanks for any advice.
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The windshield wiper motor I have does indeed have the "ground" shorted to the frame (or case). Does that cause a problem when you use an H-bridge to reverse the motor direction? I had not thought of that, but I guess it might.
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I would imagine that they are not shorted to the frame in most cases. Your windows don't only roll one direction do they? I've never seen a window motor that has some form of transmission that allows for switching directions. The leads would have to be isolated from the case, generally a car frame is grounded and this includes the doors and most metal panels attached to the car.
Edit: I haven't seen this, but I would imagine two sets of windings could be used inside the motor and both leads could be 'hot' and the case could be grounded, but this sounds more expensive than it is worth.
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I've used windshield motors on 2 projects, an e-dolly which carries tools around for me and an e-lawnmower. The lawnmower used a frame from an Black & Decker electric lawnmower which is plastic. This isolated the motors... no problem. The mower uses 4 drive wheels and tank style steering and will go over just about anything in a lawn.
The e-dolly uses an aluminum frame with the motor mounts isolated on wood blocks (conveniently available) though you could use any durable insulating material. I can stand on the dolly and it will easily transport me up and down the driveway.
These are powerful motors good for use with wheels up to about 8" in dia.
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I would imagine that they are not shorted to the frame in most cases. Your windows don't only roll one direction do they? I've never seen a window motor that has some form of transmission that allows for switching directions. The leads would have to be isolated from the case, generally a car frame is grounded and this includes the doors and most metal panels attached to the car.
Edit: I haven't seen this, but I would imagine two sets of windings could be used inside the motor and both leads could be 'hot' and the case could be grounded, but this sounds more expensive than it is worth.
Hmmm, bingo... Some do rotate to one direction only... It's very simple in fact.... If something rotates on a cycle and you exploit the amplitude of only one oscillation, the resulting motion is in fact a sine or cosine with a fixed amplitude....
So yes they might be working in only one direction... whether the case is grounded or not, that I don't know...