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Home > Archive > Alternative Power sources > September 2007 > Re: Attn : Nick Pine - got a live one for ya ! Re: Too much humidity from my swamp cooler
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Re: Attn : Nick Pine - got a live one for ya ! Re: Too much humidity from my swamp cooler
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| nicksanspam@ece.villanova.edu 2007-09-16, 5:25 pm |
| Bob Pietrangelo <bobp3@comcast.net> wrote:
[color=darkred]
>My son and I are going on Sunday, when are you speaking.
At 2:30 on Saturday in the yellow flag tent (1 of 8). PhD Nathan Hurst
will be talking about his Mazda radiator solar heating experiments in
Australia at 3:30 on Sunday in the red flag tent (a late program change.)
PhD Rich Komp will be talking about energy-efficient food storage at 3:30
on Saturday in the blue flag tent and new developments in photovoltaics
at 4:30 on Sunday in the white flag tent. We'll be at an "ask the engineer"
table at other times. About 6,000 people came the first year and 12,000
last year. Will there be 24,000 this year? :-)
BTW, it would simplify the damper arrangements if we could pull hot sunspace
air through the radiator with its fans during the day to heat water and push
house air through it to heat the house at night. Does anyone know if late
model Japanese radiators (eg my $35 '95 Mitsubishi 2.0 Eclipse) 12V fans have
brushes that are slanted in the normal rotation direction in a way that lets
the commutators quickly grind them up in reverse?
Thanks,
Nick
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| .p.jm@see_my_sig_for_address.com 2007-09-16, 5:25 pm |
| On 16 Sep 2007 15:02:03 -0400, nicksanspam@ece.villanova.edu wrote:
>Bob Pietrangelo <bobp3@comcast.net> wrote:
>
>
>
>At 2:30 on Saturday in the yellow flag tent (1 of 8). PhD Nathan Hurst
>will be talking about his Mazda radiator solar heating experiments in
>Australia at 3:30 on Sunday in the red flag tent (a late program change.)
>PhD Rich Komp will be talking about energy-efficient food storage at 3:30
>on Saturday in the blue flag tent and new developments in photovoltaics
>at 4:30 on Sunday in the white flag tent. We'll be at an "ask the engineer"
>table at other times.
That would be during your potty break, I assume ?
PHDs ! PHDs! PHDs ! Boy howdy mama, gotta be some good
stuff there with all dem PHDs !!!!
> About 6,000 people came the first year and 12,000
>last year. Will there be 24,000 this year? :-)
Sounds like a good weekend in Reno.....
>BTW, it would simplify the damper arrangements if we could pull hot sunspace
>air through the radiator with its fans during the day to heat water and push
>house air through it to heat the house at night. Does anyone know if late
>model Japanese radiators (eg my $35 '95 Mitsubishi 2.0 Eclipse)
You bought a new car ? Congrats !
> 12V fans have
>brushes that are slanted in the normal rotation direction in a way that lets
>the commutators quickly grind them up in reverse?
>
>Thanks,
>
>Nick
--
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| nicksanspam@ece.villanova.edu 2007-09-16, 5:25 pm |
| <.p.jm@see_my_sig_for_address.com> wrote:
>
> You bought a new car ? Congrats !
Just a part of one. We could do this with about $800 of standard HVAC stuff.
[color=darkred]
My mechanic friend says no. Reversing should be OK.
Nick
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| Neon John 2007-09-16, 5:25 pm |
| On 16 Sep 2007 15:34:25 -0400, nicksanspam@ece.villanova.edu wrote:
>
>My mechanic friend says no. Reversing should be OK.
You're mechanic friend is wrong for most automotive DC motors. The issue isn't brush
slant because most small motors don't use brush slant. The issue is brush timing.
The reaction of the field and armature magnetic fields forces the field toward the
edge of the pole. It is desirable to commutate at a zero potential point and that
means where the field is weakest. Therefore brushes are advanced over the static
timing to the new dynamic neutral position. If the motor is reversed without
re-timing the brushes, there will be heavy sparking, rapid commutator and brush wear,
high current draw, overheating and low power. The timing changes with load but since
a fan is a more or less constant load, static timing works.
Larger more expensive DC motors frequently have "interpoles", also known as
"commutation windings" to stabilize the commutation point but small cheap automotive
motors don't.
The old EV warrior electric bicycle used two Ford radiator fan motors for propulsion.
One on either side of the wheel, shafts pointing toward each other with a rubber
roller connecting the two. The roller contacted and drove the tire. These motors
came in left and right-hand rotation versions.
If one attempts to run one backwards it does everything I described above. When the
company went bankrupt I bought a box full of the motors and have used them on a
variety of small EV projects so I'm quite familiar with the characteristics.
On the web there are various descriptions of techniques people have used to reverse
these motors. For some reason there were many more of one type than the other on the
surplus market so there was a demand for reversing techniques. It looked like a lot
of work to me, for this motor uses a radial commutator and the brushes are riveted to
the end bell plus the motor is assembled with crimped joints.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
You have a magnetic personality... That must be why all your mental floppies are blank.
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| daestrom 2007-09-17, 5:25 pm |
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<nicksanspam@ece.villanova.edu> wrote in message
news:fcm9fu$8hi@acadia.ece.villanova.edu...
> Jeff <dont_bug_me@all.uk> wrote:
>
>
> Most AC fans are only rated for 104 F.
>
> I spoke with a motor guy who didn't think brush timing would be an issue.
>
Nah... It will just burn the edge of the commutator bars and the brushes
will wear out faster. Once the bars are burned you'll have to dress them up
each time you replace the brushes, otherwise the pitting will mechanically
wear the brushes more and more. But other than that, you shouldn't have too
much trouble :-/
How you plan on reversing these anyway, open 'em up and reverse the polarity
going to the field or to the armature? (hint: don't reverse both or you get
nowhere). Reversing the applied voltage to the motor leads won't work
unless it's a PM motor.
daestrom
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<nicksanspam@ece.villanova.edu> wrote in message
news:fck0g1$7v2@acadia.ece.villanova.edu...
> <.p.jm@see_my_sig_for_address.com> wrote:
>
>
> Just a part of one. We could do this with about $800 of standard HVAC
> stuff.
>
>
> My mechanic friend says no. Reversing should be OK.
I concur; brushes are usually mounted at a perfect 90* angle, but =do=
make certain you have a spare set of brushes available before making this
setup anything permanent. Finding spares can be a real PITA.
>
> Nick
>
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"Neon John" <no@never.com> wrote in message
news:sb6re3t7eifb1cmuqb116dp53lu3qu0p3l@4ax.com...
> On 16 Sep 2007 15:34:25 -0400, nicksanspam@ece.villanova.edu wrote:
>
>
>
> You're mechanic friend is wrong for most automotive DC motors. The issue
> isn't brush
> slant because most small motors don't use brush slant. The issue is brush
> timing.
Aaahhh so. Number One Son is learning.
> The old EV warrior electric bicycle used two Ford radiator fan motors
We used to have a cartoon in the window of our parts dept w/a guy
holding one, saying "I need everything but this for an '87 Taurus." :-)
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"Anthony Matonak" <anthonym40@nothing.like.socal.rr.com> wrote in message
news:46edad44$0$18916$4c368faf@roadrunner.com...
> Neon John wrote:
>
> I guess the simple solution would be to bolt another fan on the other
> side of the radiator.
>
> Anthony
Pardon me for being thick; is he trying to run the motor in reverse, or
convert it to run in either direction at a flip of a switch????????
inquiring minds want to know....
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| Neon John 2007-09-18, 3:25 am |
| On Mon, 17 Sep 2007 17:46:14 -0400, "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com>
wrote:
>
>Nah... It will just burn the edge of the commutator bars and the brushes
>will wear out faster. Once the bars are burned you'll have to dress them up
>each time you replace the brushes, otherwise the pitting will mechanically
>wear the brushes more and more. But other than that, you shouldn't have too
>much trouble :-/
Yup. "Motor guys" scare me with what they don't know. I moonlight in a friend's
motor repair shop, in part, to help keep him out of trouble :-)
Automotive radiator fan motors don't permit changing the brushes, at least not
easily. All the connections including the brush pigtail leads are spot-welded and
the can is either pressed or welded together. The motors are effectively disposable.
Here's a page on changing the timing of the EV Warrior (Ford radiator fan motor)
timing, as an example of what is involved:
http://redneckrobots.com/ev/mod.htm
At 140,000 miles I recently had to replace the radiator fan motor on my Caprice. It
quit running due to brush wear. Being an engineer and a motor guy, I decided that
I'd rebuild the old one and put it on the shelf as a spare. This motor is pressed
together so I pressed it apart on my arbor press.
The destruction was impressive. The brushes were worn to nubs. The commutator bars
were worn to within a few thousandths of breaking through to the underlying plastic.
The windings were spot-welded to the armature bars, making replacement fairly
impractical. There were grooves worn in the shaft under both bearings. Whomever did
the engineering on this motor nailed the lifecycle, causing everything to wear out
together. It went into the garbage.
>
>How you plan on reversing these anyway, open 'em up and reverse the polarity
>going to the field or to the armature? (hint: don't reverse both or you get
>nowhere). Reversing the applied voltage to the motor leads won't work
>unless it's a PM motor.
Almost all these motors are permanent magnet field so reversing is just a matter of
reversing the polarity. If I were going to try to reverse one of these then I'd open
it up and time the brushes mechanically neutral. The sparking and other bad behavior
will be about the same in both directions but it will be less than if a properly
timed motor is run against the timing.
If you have reversible drill and can see the commutator then you can observe a
neutrally-timed motor. The sparking is fairly heavy under load in either direction.
Since a drill motor's lifetime is typically measured in hundreds of hours, it doesn't
matter much.
There are other problems to deal with. Many radiator fan blades are held onto the
shaft by simple threads. Reverse the rotation and the fan unscrews from the shaft.
Also few fan blades are bi-directional. They blow air efficiently in one direction
only. In the reverse direction they primarily make noise. A quick peek at the blade
on most any radiator fan will reveal just how asymmetrical they are. Shallow attack
angle quickly ramping up to a sharp discharge angle. They just don't work in
reverse.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
What do you call a blonde's dildo? Pneumatic tool.
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