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Using Arduino => General Electronics => Topic started by: Aqualize on Nov 23, 2012, 01:29 am

Title: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 23, 2012, 01:29 am
Hello

For a big project I need a strong and slow engine. As I gathered it is common get a used windshield wiper motor. I got a used one from my neighbor who fixes cars but the motor turned out to be something strange, not like any other wiper motor I can find on the internet (doesn't look like them either). I experimented with it to understand it. If I remember it has 5 connections and I guess two are for this auto-parking feature but I'm not interested in that. Leaves three connections and now to bizarre(to me).
Let me call them c1, c2 and c3. The possible connections that can be made with a power source (plus and minus) is listed here and what happens:
+c1 -c2 motor rotates one direction.
-c1 +c2 motor rotates the same direction (even though I reversed polarity).
+c3 -c2 motor turn the other direction.
-c3 +c2 motor turns the other direction (again, I reversed polarity and it spins the same, but at a different speed).
+c1 -c3 short circuits
-c1 +c3 short circuits

The thing about different speed I guess is for the different speeds of the wipers.
And the c2 should be the "ground", because it would be in touch with the rest of the metal of the car it was mounted in at the beginning.

I understood that I needed to control high currents with the arduino, but I didn't want a mechanical relay (the direction might be changing quite often, perhaps a few times per second). I bought a Parallax HB-25 Motor Controller (http://www.parallax.com/tabid/768/ProductID/64/Default.aspx) (bought it in fact before my strange wiper motor).


You might see the problem here, to control direction of a motor the HB-25 changes polarity of its output ports (M1 and M2). That wouldn't help me.
And now I'm getting out into the more deep waters, for me at least. I think that adding a few diodes might solve my problem.

I attach my suggestion. I hope people can tell me if this will do what I want. When the HB-25 puts positive on M1 and negative on M2 the motor rotates one way and when changing polarity of M1 and M2 it rotates the other way.
Second, I need help with selecting the diodes. I plan to buy from conrad.com, they have a big selection of diodes (http://www.conrad.com/Diodes.htm?websale7=conrad-int&ci=SHOP_AREA_17304). Is a "standard" diode okay? Or a Schottky diode? What I've tried to read other diodes aren't of interest here.
So... the voltage I guess will be around 13-14VDC and the motor might get stalled (high current draw). I don't know anything about the motor's power. But looking around there seems to be wiper engines in the range of 50-150 watt. So if buy diodes that are good for up to 15A, which should I buy? Or if the price would be the close for 25A I would take that (25A is the max continuous for the motor controller).
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: zoomkat on Nov 23, 2012, 02:00 am
The below has some wiper motor wiring info.

http://www.youtube.com/watch?v=1Ww5-pmiokc
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 23, 2012, 02:17 am

The below has some wiper motor wiring info.

*youtube*


I have seen that video but that isn't similar to mine, neither wiring or look. As seen the output shaft of the typical motor in the video is at a right angle to the axle of the DC motor inside it. My motor has the output shaft (after reduction gears) parallel to the DC motor axle. I don't have it here so I can't take a picture of it, sorry.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: zoomkat on Nov 23, 2012, 03:10 am
Stuff to look at. You might ask the source of the wiper motor what car it came out of. The short circuit wires might be across an internal limit switch when it is closed

https://www.google.com/search?q=Windshield+Wiper+Motor+Wiring&num=100&hl=en&lr=&tbo=u&as_qdr=all&tbm=isch&source=univ&sa=X&ei=1NauUKT0IcPf0gHG8oCABQ&ved=0CIcBELAE&biw=1201&bih=641
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 23, 2012, 03:29 am

Stuff to look at. You might ask the source of the wiper motor what car it came out of. The short circuit wires might be across an internal limit switch when it is closed

https://www.google.com/search?q=Windshield+Wiper+Motor+Wiring&num=100&hl=en&lr=&tbo=u&as_qdr=all&tbm=isch&source=univ&sa=X&ei=1NauUKT0IcPf0gHG8oCABQ&ved=0CIcBELAE&biw=1201&bih=641


The neighbor had pulled it out of some car at the scrap yard. He don't remember which car. There are no markings or name at all on it of what I remember (the motor is at my parents house, can't check).
But I did sit and test all the ports on it, had connected a ATX PSU modded for such task.
I tried to pry it open but I couldn't. It is something internally that makes it behave as it do. As far as I know all DC motors change direction when the polarity is changed, or this is some kind of strange engine that won't do that.

Just to clarify, it is not that kind of small motor that connects directly to a wiper via a shaft (used in old tractors and trucks), which also has automatic reversal at the end zones.
On my motor it is a little gear, no long shaft out of it. The linkage to a standard wiper blade setup would be connected to this gear.


But given the characteristics of it what I wrote in the first post, would the diode setup work?
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: retrolefty on Nov 23, 2012, 03:41 am
Quote
But given the characteristics of it what I wrote in the first post, would the diode setup work?


Your diode steering circuit looks like it would work to me. I would use diodes with as high a current rating as you can find (and afford of course). As a second level safety item I would consider adding one automotive style fuse on the single common - lead feeding the motor. Who knows what the stall current would be if the motor was to jam or whatever and while the motor driver seems to have some fuse protection I would consider this second one maybe sized closer (but still more) to what the motor actually draws in your application. Note that because of the voltage drop (across two diodes) there is likely going to be a little 'dead band' around the neutral control speed setting being sent to the controller, but you can probably deal with that in your software if it becomes as issue in your control algorithm.

Lefty
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: zoomkat on Nov 23, 2012, 04:02 am
There could be relays internal to the motor assembly.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 23, 2012, 04:23 am
I remembered I had an arduino with breadboard... I tested the wiring and instead of the motor I had 1 LED+resistor going from "motor 1st +" to "-" in the wiring diagram, and another LED+resistor going from "motor 2nd+" to "-". And then to be sure I switched the LEDs' legs and as expected it didn't shine then but when switching positive and negative input the breadboard the first LED went dark and the other one lit up.

I'm going to buy a car fuse assortment box for mini ATC fuses (small flat car fuses), that is the type that the motor controller has. Because I agree that 25A is probably to much. 10A or 15A will be better. You wrote "single common - lead feeding the motor". Do you mean I anyway should have an extra fuse after the motor (the "-" connector of the motor) or do I get away from this by changing the fuse on the controller.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 23, 2012, 04:45 am
I found this diode, what do you all think?
http://www.produktinfo.conrad.com/datenblaetter/150000-174999/160744-da-01-en-SCHOTTKY_DIODE_DSS25_0025B_TO_220_AC.pdf
(no, I won't forgetting cooling of it)
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: be80be on Nov 23, 2012, 05:47 am
Sounds to me like you have a window motor not a wiper motor.

Window motors have gears on them wiper motors don't have any that you can see.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 23, 2012, 11:04 am

Sounds to me like you have a window motor not a wiper motor.

Window motors have gears on them wiper motors don't have any that you can see.

I didn't know how those looked like so I googled it. Well the principle looks the same as the wiper motor. It has a worm gear reduction. The gears aren't similar either, mine has a lot more teeth, I think is made to be connected to some component with inner teeth (like putting a drive shaft on it or so).
I started considering the possibility that it might like some vital components. But a wiper motor has a worm gear that slows it down a lot. This output gear already only turns like 100 rpm (i.e. a few revolutions per second unloaded) which could be suitable for a wiper motor.

To put an end to figuring this out I will ask my mom if she can try to take a few photos of this and send it over (I live far away) to me so I can display it to you guys. But I will make my online purchase tonight (CET timezone) because that webshop has come up with the idea to import the "black friday" phenomena here, so they have a general discount for all purchases.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: zoomkat on Nov 23, 2012, 03:25 pm
Ebay h-bridges are getting cheaper.

http://www.ebay.com/itm/Arduino-240W-High-power-H-Bridge-Motor-Driver-Module-Smart-Car-Driver-/330817755465?pt=LH_DefaultDomain_0&hash=item4d06465949

http://www.ebay.com/itm/43A-DC-Motor-Driver-Drive-Module-H-Bridge-PWM-Contro-For-Robot-Smart-Car-Arduino-/300818612987?pt=LH_DefaultDomain_0&hash=item460a2fc2fb

http://www.ebay.com/itm/30A-H-bridge-Coreless-Motor-Driver-Forward-Reversion-Brake-For-Smart-Car-Arduino-/180983568079?pt=LH_DefaultDomain_0&hash=item2a237616cf

http://www.ebay.com/itm/Dual-H-Bridge-Optoisolate-ATMEL-ATTINY-2313-based-Motor-driver-Arduino-PIC-/271028808736?pt=LH_DefaultDomain_0&hash=item3f1a936c20

http://www.ebay.com/itm/50A-H-bridge-Coreless-Motor-Driver-Forward-Reversion-Brake-For-Smart-Car-Arduino-/180984278054?pt=LH_DefaultDomain_0&hash=item2a2380ec26

Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 23, 2012, 05:20 pm
Well I already have the Parallax HB-25 motor controller (HB = H-Bridge) so I don't need any of those I think.

Here are the pictures. The bend part of the mounting bracket is pointed away from the motor when mounted onto it.
And the white cable around the output gear was only for me to visually estimate the rpm when testing.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: be80be on Nov 25, 2012, 06:47 pm
Well I can tell you one thing for sure that's a wiper motor. Looks like a older chevy
It should have wiring like this Low and high.  So you end up with 5 wire

Ground and supply and then 3 for speed changes.  A little arm slipped over the shaft and had a bolt that locked it to those spines.

More then likely wired like this (http://www.freepatentsonline.com/6600281-0-large.jpg)  
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: dc42 on Nov 25, 2012, 07:37 pm

I found this diode, what do you all think?
http://www.produktinfo.conrad.com/datenblaetter/150000-174999/160744-da-01-en-SCHOTTKY_DIODE_DSS25_0025B_TO_220_AC.pdf
(no, I won't forgetting cooling of it)


Measure the resistance of the motor windings with a multimeter and divide that into the supply voltage you will be using to get the stall current (Ohm's law). If it's less than 25A then that diode will be fine, with appropriate heatsinking if necessary. If it's a lot less than 25A, then a regular silicon power diode will be suitable and cost less. The only advantage of a Schottky diode in this application is that is has a lower voltage drop, so it dissipates less power and may not need quite as much cooling.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: be80be on Nov 25, 2012, 08:35 pm
If the wiper motor draws 25 amps it's bad almost any of the never use over a 15 amp fuse and 10 amps in newer cars is the normal.
Quote
Current. The minimum required current for the motor is 1.6 amps at 70 rpm, 0.9 amps at 41 rpm (and 4 amps if you elect to run it at 106 rpm, see note on the next page). These current ratings are for the motor spinning with no load. As you add mechanical load, these numbers can increase dramatically, doubling or even tripling under a heavy load. (When testing for torque, I found the motor to draw close to 14 amps in a stalled condition.) This factor must be taken into account when selecting a power supply. Since the motor will only use what it needs when it comes to current, it's best to provide a source with a higher current rating than you think you might need. I would recommend a 5 amp or greater supply to handle most circumstances.

And most stuff you find on the net say a 5 amp supply will run most any of them there not a power house of a motor
Quote
Contrary to what some believe, the wiper motor does not oscillate back and forth, it rotates continuously in one direction like most other motors. The rotational motion is converted to the back and forth wiper motion by a series of mechanical linkages. Here's a page that shows how this works in a car http://auto.howstuffworks.com/wiper1.htm

This type of motor is called a"gearhead" or "gear motor" and has the advantage of having lots of torque. My unscientific test (using one wiper motor and a torque wrench) found that at 12 volts, on high speed, the motor has 13.5 pound-feet and on low speed, has 17.5 pound-feet of torque.

Here a nice link http://www.scary-terry.com/wipmtr/wipmtr.htm
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: NickPyner on Nov 26, 2012, 12:37 am

[ As seen the output shaft of the typical motor in the video is at a right angle to the axle of the DC motor inside it. My motor has the output shaft (after reduction gears) parallel to the DC motor axle. I


You are right to draw attention to this, and the picture.

So, are you sure it is a wiper motor? It certainly doesn't look like one, and questioning that will not only go quite some way to explain  why you are having so much trouble with it, but also eventually explain any surprises you might get when you finally succeed - or fail.

I have never worked on a Japanese car but I don't imagine them to be any different.  I don't recall any wiper motor not having a right angle drive i.e. a worm drive. There are three glaringly obvious reason for wiper motors to use worm drive.

1. It substantially increases the torque available from a small cheap motor

2. It reduces the speed to what is needed for the job i.e. not very fast and a hell of a lot slower than what a DC motor normally delivers.

3. 1 and 2 above are achieved with just two components - the worm, integral with the motor shaft thereby not actually qualifying as component, and the large gear wheel. The alternative is a multi-component gear train - with the attendant cost, space, and reliability issues.

Further, that motor looks pretty big for a wiper motor.  Further still, I see talk of 25A but I have never known a wiper requiring anything bigger than  a 15A fuse, and that is quite often shared with something else. And while you are at it, window motors are the same, for the same reasons - with the added advantage that the worm drives fits in the door better.

I think it is sort of actuator. I have no idea what for. Actuators on cars are usually vacuum. The most interesting thing about it is that your neighbour can't remember what car it came off (if it actually came off a car). You could find that your best solution is to go to a junk yard and procure what is definitely a wiper motor - one that is actually connected to wipers.

Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: be80be on Nov 26, 2012, 02:57 am
It's a wiper motor I've seen one just like it on a old chevy dump truck. It's old like me.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 26, 2012, 09:57 am
Thank you all for your responses.
be80be seems convinced it is a form of wiper motor. I have only what heard and pieced together. It comes from a man that fixes cars at home, he said it was a wiper motor that he'd gotten from a scrapyard. On a older car I can't think on any use for such motor (slow turning, high torque) except for the wipers.
I'm going to continue assuming it is a wiper motor. Anyway if a wiper motor of similar size seems nowhere near using 25A I hope I can feel calm with my motor controller and those diodes I bought.

Well I'm not convinced by the wiring suggested by be80be (from when I tested it with trial end error) I will print it and bring it with me next time I go there and have a chance to study it more.
And the reason I don't keep it here where I live is that the intended use is as a motor for turning the steering wheel on a tractor, which is at my parents home and travel there by bus and train and is not so keen on carrying this motor back and forth. The tractor has hydraulic assisted steering (otherwise I don't think it would be enough to turn the steering wheel). But that is a subject for another thread which I hope to start if this projects gets going.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: NickPyner on Nov 27, 2012, 12:12 am
OK. The penultimate, or possibly ultimate question:

Looking at pic028, you have a bit of white cable to estimate the rpm. Did you just see that cable move momentarily, or did you see it rotate continuously in both directions?
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 27, 2012, 12:16 pm

OK. The penultimate, or possibly ultimate question:

Looking at pic028, you have a bit of white cable to estimate the rpm. Did you just see that cable move momentarily, or did you see it rotate continuously in both directions?

It moved continuously (no stuttering) for as long as I wanted it to be by having the wires in contact with the connection points. By shifting connection points I could make it go the other way. But they moved in different speed. Lets say 80 rpm and 150 rpm. That they moved in different speeds makes me think that there isn't any "low" and "high" connections, changing direction makes the high and low.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: NickPyner on Nov 27, 2012, 03:22 pm

That they moved in different speeds makes me think that there isn't any "low" and "high" connections, changing direction makes the high and low.


That's as good an explanation as any, but it may be reversing just to park.

The reason why I asked the question is that I'm sure the bit of cable  isn't wrapped round an "output  gear", it's a spline. It looks exactly like the spline for a screenwiper arm, hence my question.  If the shaft rotated about a thirty degrees and then reversed, the motor is almost certainly a windscreen wiper motor but not off a car. It's off a train or a bus, hence the size. You often see buses with the wipers going but obviously not connected and thus must have a motor for each.  It could still be a wiper motor but, if that is the case, it obviously has a large and vital part missing, the reciprocating gear. Fortunately it is not too vital for you, but the bit that connects to the spline would probably be useful. It could have been that the motor originally drove a hydraulic pump, which might have been nice for your purpose(!)
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 28, 2012, 09:59 am


That they moved in different speeds makes me think that there isn't any "low" and "high" connections, changing direction makes the high and low.


That's as good an explanation as any, but it may be reversing just to park.

The reason why I asked the question is that I'm sure the bit of cable  isn't wrapped round an "output  gear", it's a spline. It looks exactly like the spline for a screenwiper arm, hence my question.  If the shaft rotated about a thirty degrees and then reversed, the motor is almost certainly a windscreen wiper motor but not off a car. It's off a train or a bus, hence the size. You often see buses with the wipers going but obviously not connected and thus must have a motor for each.  It could still be a wiper motor but, if that is the case, it obviously has a large and vital part missing, the reciprocating gear. Fortunately it is not too vital for you, but the bit that connects to the spline would probably be useful. It could have been that the motor originally drove a hydraulic pump, which might have been nice for your purpose(!)

That's an interesting thought. Wiper motors for tractors work similar to how you describe it for other bigger machines (the arm is connected to the wiper motor directly and the motor changes direction).

Well the lack of speed makes me doubt it would be used to drive a hydraulic pump. The tractor hasn't hydrostatic steering (orbitrol). First I was thinking of affected the hydraulic valve on the servocylinder but gave up that. I think it is tightly built together so connecting some electronic valve (which I don't have and they are expensive) may not be possible. Bicycle gears of appropriate size and chain connecting the steering wheel and the electric motor is a way I think this will work, thanks to the power steering. An older tractor we have is without that I know that for such task this little motor wouldn't be enough.


But to sum it up we are waiting for me to take another look it with multimeter and wires, having a printed copy of the wiring diagram I got and see if it corresponds or not. And after that I think I will build it together as I thought with 4 diodes, smaller fuse on the motor controller and an Arduino for a bench test run. I know for sure I will visit the parents around Christmas, we'll see if I go earlier. So don't hold your breath until then! ;)
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Nov 28, 2012, 12:33 pm


[...]

[...] It could still be a wiper motor but, if that is the case, it obviously has a large and vital part missing, the reciprocating gear. Fortunately it is not too vital for you, but the bit that connects to the spline would probably be useful. [...]

As I don't have this piece my idea use the bicycle gear, somehow centered and then use the welding machine to permanently attach it.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Dec 26, 2012, 12:11 am
So it is Christmas time and I have a chance to experiment with the motor again. And the connection works as intended!
So now the two input cables, when reversed polarity also reverses direction of the motor. Those 4 diodes was the key.
I will post pictures of the whole thing when I also get the arduino to drive it via the HB-25 controller. What I've done now to test the motor is to connect it to my modded computer PSU (banana sockets on top of it for easy access).
I don't know if I'm doing it wrong with the HB-25 but I will experiment on a small DC motor I have tomorrow.
Title: Re: Connecting strange wiper motor, help selecting diodes (or other suggestion)
Post by: Aqualize on Dec 26, 2012, 07:36 pm
I thought maybe a video showed it better :)
Using the servo library I got it to work. I hooked it up to read input from the Y axis of the joystick shield.
I measured the amperage between the PSU +12V and HB25 controller's positive connector, when the motor runs at full speed with no load it uses ~2.5A. Peaks higher, especially if changing direction suddenly.

So thanks everyone for the help, the objective I needed help with by starting this thread has been archived.

http://www.youtube.com/watch?v=WmBrxlfs2Ko