On Wed, 12 Apr 2017 09:11:45 -0700,
wrote:
On 12 Apr 2017 04:01:56 GMT, "DoN. Nichols"
wrote:
I thought about that but dismissed it because I really don't know how
I would go about doing it.
You should dismiss it because it is complication you don't need. My
contact in Ford Engineering tells me that the burst test speed for
"standard" alternators (the traditional ones before they started
designing a custom alternator for every engine) is 15,000 RPM and that
they will run up to around 10,000 RPM with the engine wound out.
So you have no problem getting the power to the solenoid. The problem
will be the solenoid itself.
The only way the solenoid could work is for the plunger to be exactly
axially aligned with the shaft. If it is off-center by even a tiny
amount, the whole assembly will be out of balance. Worse, the
centrifugal force will act to bind the plunger against the wall of the
solenoid tube.
Even if you work that out the fluid (air in this case) will be
affected by the same centrifugal force. The force will either work
against or with the valve. If it work against the valve, the valve
might not open. If it works with the valve, it might not shut.
I don't fully know what you're trying to achieve but it seems to me
that a stationary solenoid, a rotary coupling such as one of these.
https://www.mcmaster.com/#rotating-couplings/=17755fj
to get the air inside the tube. If you need to flow to be abruptly
started and stopped, my approach would be capillary tubing from the
valve to the outlet, the bore of which is chosen to provide the
desired air volume when full shop air is applied from the solenoid.
Here is an example of several bore sizes.
https://www.johnstonesupply.com/sear...pillary+tubing
If your solenoid is DC it will either require a snubber or use a
switching device capable of withstanding the flyback. A pure diode
will greatly slow the closing time because the current will continue
to flow until it is dissipated in the solenoid's resistance.
If you need it to close rapidly, the usual technique is to connect a
resistor in series with the solenoid and adjust its value until the
flyback voltage is as high as tolerable. For example if your
actuating device uses a 200 volt max rating transistor, I'll allow the
voltage to rise to no more than 100 volts.
You'll need an oscilloscope to observe this. I anticipate your not
having one but you probably have a friend that does.
If you need the valve to close very rapidly, I can describe a very
simple peak/hold circuit that supplies full voltage until the solenoid
is actuated and then drops the current to the much lower holding
value. Much less current to dissipate in the snubber.
John
So maybe you could help. Sticking out the
back of the lathe will be a steel tube. Inside this tube will be the
solenoid actuated valve and counterweights so that the tube is
balanced. And the plumbing that will bring the air from the valve to
the collet closer mounted in the spindle. Into the end of this tube
will be screwed a rotary union that passes air. If I have a coil
wrapped around the steel tube won't that be a problem? What if a
plastic sleeve were to be pressed over the O.D. of the tube and the
coil wrapped on it. Would that be better? Since I can supply any
voltage to the stationary coil it seems tome that a 1:1 ratio between
the coils would be easiest to do. Does this mean that I can also get
away with just about any number of turns provided the wire can handle
the minute current? The valve only needs .2 amps to operate so the
wire can be pretty fine. The valve operates on DC but a rectifier can
be stuffed into the tube along with everything else. Will the tube
coil need a snubber diode too? Any advice?
Thanks,
Eric
John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address