Self-contained magnetic bearings
Ed Huntress
so it's not a hobbyist item. But it would be very, very cool to have some of
these suckers.
Baldor is planning to use them in some new motors, for up to 30,000 rpm.
http://www.nytimes.com/2010/01/03/business/03novel.html?hpw
--
Ed Huntress
Grumpy
"Ed Huntress" <hunt...@optonline.net> wrote in message
news:4b4011c3$0$22541$607e...@cv.net...
compressor. These things wizz around at about 30,000 RPM, and have an active
control system that maintains the shaft in the centre of the bearing. I
can't remember the name, but it was an Australian design that couldn't raise
enough money to go into production ( Never ending storey, here in Auz) so
managed to get a Canadian company involved. I saw an early production model
set up in a test rig here in Melbourne. The big advantage that I saw, was
that it was totally unlubricated, so no oil return systems were required.
They only made the one size,as it was aimed at the commercial (not
industrial ) sector. My first quetion was" What happens in a power failure?"
They assured me that it maintained its centre untill it slowed down to about
a thousand revs, then dropped onto some plastic wear blocks. They did not
offer to demonstrate.
Bill Noble
vacuum
"Ed Huntress" <hunt...@optonline.net> wrote in message
news:4b4011c3$0$22541$607e...@cv.net...
Grumpy
"Bill Noble" <nob...@nowhere.invalid> wrote in message
news:hhpbi2$112$1...@news.eternal-september.org...
> air bearings are much cheaper and work if you don't need to operate in a
> vacuum
Not much good in a refrigeration compressor!
Ignoramus7943
Here's a stupid question. Suppose that your device is running happily
on those magnetic bearings.
Then, wham, power to them goes out.
What will happen?
i
Ed Huntress
"Ignoramus7943" <ignora...@NOSPAM.7943.invalid> wrote in message
news:fbGdnbJEl7ffet3W...@giganews.com...
That's answered in the brief article linked to above.
--
Ed Huntress
Ignoramus7943
>
> "Ignoramus7943" <ignora...@NOSPAM.7943.invalid> wrote in message
> news:fbGdnbJEl7ffet3W...@giganews.com...
>>
>> On 2010-01-03, Ed Huntress <hunt...@optonline.net> wrote:
>>> This is a very cool technology. The price is a bit
>>> steep...$45,000...<gag>,
>>> so it's not a hobbyist item. But it would be very, very cool to have some
>>> of
>>> these suckers.
>>>
>>> Baldor is planning to use them in some new motors, for up to 30,000 rpm.
>>>
>>> http://www.nytimes.com/2010/01/03/business/03novel.html?hpw
>>>
>>
>> Here's a stupid question. Suppose that your device is running happily
>> on those magnetic bearings.
>>
>> Then, wham, power to them goes out.
>>
>> What will happen?
>>
>> i
>
> That's answered in the brief article linked to above.
>
Ed, I did not see any answer.
i
Joseph Gwinn
"Ed Huntress" <hunt...@optonline.net> wrote:
This caught my eye too.
Here is the company's website: <http://www.synchrony.com/>.
And the relevant patent application is US 2009/0265038 A1.
Joe Gwinn
Ed Huntress
"Ignoramus7943" <ignora...@NOSPAM.7943.invalid> wrote in message
Oh, sorry, Iggy. I bounced all over with the links after I read that, and I
see that I actually got the answer to that question at Synchrony's site.
Try this, and search down the page for this question: "What happens if the
shaft contacts the auxiliary bearing due to a total loss of power?"
http://www.synchrony.com/frequently-asked-questions/default.aspx#16
--
Ed Huntress
Ned Simmons
Similar to the concept of incorporating the amp and motion controller
in the same package as a servo motor, for example...
--
Ned Simmons
Ned Simmons
<nob...@nowhere.invalid> wrote:
>air bearings are much cheaper and work if you don't need to operate in a
>vacuum
>
Air bearings are certainly much cheaper, but they can have stability
problems and tend to fail in spectacular fashion. I worked on a
project a few years ago where we were considering magnetic bearings
specifically for their ability to compensate for instability and load
imbalance on the fly. SKF demo'ed a high speed spindle for us. The
motor was barely audible as we sat in a conference room and the motor
spun at 30,000 RPM in the middle of the table.
But it was godawful expensive, and we ultimately used conventional
ceramic bearing spindles.
--
Ned Simmons
DoN. Nichols
>
> "Ignoramus7943" <ignora...@NOSPAM.7943.invalid> wrote in message
> news:ysCdnQH6yJn0cd3W...@giganews.com...
>> On 2010-01-03, Ed Huntress <hunt...@optonline.net> wrote:
>>>
>>> "Ignoramus7943" <ignora...@NOSPAM.7943.invalid> wrote in message
>>> news:fbGdnbJEl7ffet3W...@giganews.com...
[ ... ]
>>>> Here's a stupid question. Suppose that your device is running happily
>>>> on those magnetic bearings.
>>>>
>>>> Then, wham, power to them goes out.
>>>>
>>>> What will happen?
>>>>
>>>> i
>>>
>>> That's answered in the brief article linked to above.
>>>
>>
>> Ed, I did not see any answer.
>>
>> i
>
> Oh, sorry, Iggy. I bounced all over with the links after I read that, and I
> see that I actually got the answer to that question at Synchrony's site.
>
> Try this, and search down the page for this question: "What happens if the
> shaft contacts the auxiliary bearing due to a total loss of power?"
>
> http://www.synchrony.com/frequently-asked-questions/default.aspx#16
However, I think that the assumption is that if power fails to
the bearing, it fails to everything else, too. If something else is
providing the power to rotate the load (e.g. a steam or gas turbine),
and it is not linked into the power failure sensors in the magnetic
bearing with a fail-safe, things could get rather exciting.
Enjoy,
DoN.
--
Email: <dnic...@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
sta...@prolynx.com
Been available for quite a few years in fans, I've been gradually
replacing old computer fans with ones with mag-lev bearings as they
gum up. No failures yet. They run about twice the price of ball
bearing jobs. Mean time before failure is waaay out there. The trick
is to scale the technology up so there's a payback within a reasonable
time. Or use it where lube failure costs a lot more than just the
failed motor, like a computer.
Stan
Norman Yarvin
> Try this, and search down the page for this question: "What happens if the
> shaft contacts the auxiliary bearing due to a total loss of power?"
>
> http://www.synchrony.com/frequently-asked-questions/default.aspx#16
The answer probably eventually should be:
"In that case we use the motor that's driving the shaft as a
generator, and draw power from its rotational inertia in order to
keep the bearing operational until speed is low enough not to
matter. This enables us to have the auxiliary bearings last
indefinitely, unlike the old versions of our bearings, in which
the auxiliary bearings might only survive ten power losses, which
meant that you really needed a UPS to keep them powered, as we
still recommend if you have the old versions installed."
But they evidently haven't gotten around to implementing that feature
yet... since that webpage, as it stands, only describes what I'm calling
'the old versions'.
--
Norman Yarvin http://yarchive.net
Norman Yarvin
<sta...@prolynx.com> wrote:
>Been available for quite a few years in fans, I've been gradually
>replacing old computer fans with ones with mag-lev bearings as they
>gum up. No failures yet. They run about twice the price of ball
>bearing jobs. Mean time before failure is waaay out there.
Although those are nice, they aren't actually mag-lev bearings; instead
they're just plain bearings (sleeve bearings) which are magnetically
pre-loaded so that the thrust loads are in the opposite direction from
what they would otherwise be. That is, the magnet's pull counters and
overpowers the fan's aerodynamic thrust. I think the idea is that it's
better to take the thrust load on the end of the shaft than it is to take
it on a snap ring, since the end of the shaft has more surface area to
bear the load.
Computer fan terminology seems to be driven more by marketing than by
engineering precision; that same basic idea -- magnetic preload -- is
called by a variety of names, including "fluid dynamic bearing" and
"magnetic barometric bearing", depending on who is selling it. And if
you really want to be amused, try guessing what an "air rifle bearing"
is. (Can you shoot squirrels with it?)
Real mag-lev bearings can't be done by merely adding permanent magnets to
a bearing; instead they require electromagnets driven by a controller
that continually senses how far the shaft is from its desired position,
and activates the electromagnets to push it back. Thus the high price.
Winston
(...)
> That is, the magnet's pull counters and
> overpowers the fan's aerodynamic thrust.
OH!
I studied a cross - section drawing and tried to understand why
the repulsion of the 'levitation' magnet wouldn't just push the
blade assembly against the axial stop at the end of the sleeve
bearing travel. Now I grok.
Thanks!
--Winston
--
Congratulations Robert Piccinini and Steven A. Burd, WalMart Publicists of the Year!
John R. Carroll
> On 2010-01-03, Ed Huntress <hunt...@optonline.net> wrote:
>
>> Try this, and search down the page for this question: "What happens
>> if the shaft contacts the auxiliary bearing due to a total loss of
>> power?"
>>
>> http://www.synchrony.com/frequently-asked-questions/default.aspx#16
>
> The answer probably eventually should be:
The answer is:
Regenerative braking.
Feedback loops have gotten pretty fast and they run either open or closed.
--
John R. Carroll
Martin H. Eastburn
It can be planned in the heavy stone wheels that spin through periods of time
before a generator can come up if really bad. And if the wheel goes crazy
the direction it blows through a building can be defined.
Martin