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Discussion Starter #1
Got a theoretical question for the engineers out there to shoot down ;)

Would it be possible to create a magnetically coupled torque converter using
permanent and or electromagnets?
Picture a flywheel sized disc with alternating polarity permanent magnets
attached to its face. One on the motor and one on the drive shaft facing
each other in close proximity with a mechanism to vary the air gap between
them. At low torque the wheels would be "locked" together. From a dead stop
the wheels would be allowed to "slip" so the motor would not be "lugged" at
low speeds. I think i read somewhere that the magnetic slip actually creates
heat, possibly as much as if it were a regular friction clutch. Comments
welcome. Al

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Discussion Starter #4
Several years ago Eaton Corp made a unit called an Eddy Current Clutch which
worked like you are describing. I ran into several of them on some
harvesting equipment where they were used as a speed control. The model I
worked with looked like a "normal" motor with a shaft out each end. It
fooled many farmers since without the controller turned on it acted like the
motor shaft was "broken" as you turned one end the other end didn't move.
I believe the insides were actually a cup shape that fit over the armature
and I expect there was a bearing in the middle. It used slip rings to get
power to the windings on one of the shafts. Power from a standard motor was
coupled to one end of the unit and by varying the voltage to the windings
the output shaft would vary its speed up to match the input shaft speed. I
seem to remember that the control voltage topped out around 90 VDC.

respectfully,
John
----- Original Message -----
From: "Al" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Wednesday, October 24, 2007 8:32 PM
Subject: [EVDL] magnetic shaft coupling?


> Got a theoretical question for the engineers out there to shoot down ;)
>
> Would it be possible to create a magnetically coupled torque converter
> using
> permanent and or electromagnets?
> Picture a flywheel sized disc with alternating polarity permanent magnets
> attached to its face. One on the motor and one on the drive shaft facing
> each other in close proximity with a mechanism to vary the air gap between
> them. At low torque the wheels would be "locked" together. From a dead
> stop
> the wheels would be allowed to "slip" so the motor would not be "lugged"
> at
> low speeds. I think i read somewhere that the magnetic slip actually
> creates
> heat, possibly as much as if it were a regular friction clutch. Comments
> welcome. Al
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

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Discussion Starter #5
HI- All
Google Magna Drive

Another intresting device is the magnetic base used with a dial
indicator.It couples and uncouples by
rotating a magnet in a metal base. I think it's sort of like sliding a
magnet off of a steel table instead of
trying to lift it. Can some one calculate the difference between sliding
and lifting? -FT.


> [Original Message]
> From: Al <[email protected]>
> To: Electric Vehicle Discussion List <[email protected]>
> Date: 10/24/2007 10:33:50 PM
> Subject: [EVDL] magnetic shaft coupling?
>
> Got a theoretical question for the engineers out there to shoot down ;)
>
> Would it be possible to create a magnetically coupled torque converter
using
> permanent and or electromagnets?
> Picture a flywheel sized disc with alternating polarity permanent magnets
> attached to its face. One on the motor and one on the drive shaft facing
> each other in close proximity with a mechanism to vary the air gap
between
> them. At low torque the wheels would be "locked" together. From a dead
stop
> the wheels would be allowed to "slip" so the motor would not be "lugged"
at
> low speeds. I think i read somewhere that the magnetic slip actually
creates
> heat, possibly as much as if it were a regular friction clutch. Comments
> welcome. Al
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev



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Discussion Starter #7
The Subaru Justy with the continuously variable transmission worked in a similar way. Instead of a variable gap, it had a magnetic fluid between 2 concentric drums. With modest current the 2 drums would lock together, but would slip at low currents.

----- Original Message ----
From: Al <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Wednesday, October 24, 2007 10:32:13 PM
Subject: [EVDL] magnetic shaft coupling?


Got a theoretical question for the engineers out there to shoot down ;)

Would it be possible to create a magnetically coupled torque converter
using
permanent and or electromagnets?
Picture a flywheel sized disc with alternating polarity permanent
magnets
attached to its face. One on the motor and one on the drive shaft
facing
each other in close proximity with a mechanism to vary the air gap
between
them. At low torque the wheels would be "locked" together. From a dead
stop
the wheels would be allowed to "slip" so the motor would not be
"lugged" at
low speeds. I think i read somewhere that the magnetic slip actually
creates
heat, possibly as much as if it were a regular friction clutch.
Comments
welcome. Al

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http://lists.sjsu.edu/mailman/listinfo/ev




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Discussion Starter #9
Al wrote:
> Would it be possible to create a magnetically coupled torque converter
> using permanent and/or electromagnets?

Sure! They are available commercially. Many styles and types.

> I think i read somewhere that the magnetic slip actually creates
> heat, possibly as much as if it were a regular friction clutch.

Yes. All the normal ones convert all the slip energy into heat. This is
a big disadvantage compared to a true hydraulic torque converter, which
can literally multiply the torque. For example, when the output is at
1/3rd the RPM of the input, the output torque is about 2.5 times greater.

Electric systems can do this, too; but it requires that they be built
more like a motor-generator setup.

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Discussion Starter #10
How did it get diffferent gear ratios?
That would only work as a clutch.

David Dymaxion wrote:
> The Subaru Justy with the continuously variable transmission worked in
> a similar way. Instead of a variable gap, it had a magnetic fluid
> between 2 concentric drums. With modest current the 2 drums would lock
> together, but would slip at low currents.
>
> ----- Original Message ----
> From: Al <[email protected]>
> To: Electric Vehicle Discussion List <[email protected]>
> Sent: Wednesday, October 24, 2007 10:32:13 PM
> Subject: [EVDL] magnetic shaft coupling?
>
>
> Got a theoretical question for the engineers out there to shoot down ;)
>
> Would it be possible to create a magnetically coupled torque converter
> using
> permanent and or electromagnets?
> Picture a flywheel sized disc with alternating polarity permanent
> magnets
> attached to its face. One on the motor and one on the drive shaft
> facing
> each other in close proximity with a mechanism to vary the air gap
> between
> them. At low torque the wheels would be "locked" together. From a dead
> stop
> the wheels would be allowed to "slip" so the motor would not be
> "lugged" at
> low speeds. I think i read somewhere that the magnetic slip actually
> creates
> heat, possibly as much as if it were a regular friction clutch.
> Comments
> welcome. Al
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>
> _______________________________________________
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