Wierd application, hypothetical question.

[justin ivan]

Ahh now we metnion the mighty VW, these are close to my heart(if you 
couldn't tell by my e-mail addy) The new vw turbodiesel is indeed capable or 
over 150hp, the new european model in fact has 150hp from the factory, of 
course they also use a variable vane turbo. Lots of neat tech in those cars.
   Back to the stepper motor, the control circuit would be pretty easy, 
should be able to make a simple look-up table that says for these engine 
parameters (which I am not sure what is measured on a diesel) and then move 
the stepper motor a certain amount. The movement of the stepper motor would 
be the easy part as control circuits are out there, the look-up table beyond 
my knowledge right now but check the archives.
As far as the linkage to the control pin, might not be as hard as you think, 
lots of options, workm drive, simple rack and pinion or even a simple screw 
drive. I can envisiona few options, get me off-line if you want to discuss 
further, I don't want to get this thread too far off topic.


>From: "Shirley, Mark R" <MarkRShirley at eaton.com>
>Reply-To: diy_efi at diy-efi.org
>To: "'diy_efi at diy-efi.org'" <diy_efi at diy-efi.org>
>Subject: RE: Wierd application, hypothetical question.
>Date: Wed, 6 Dec 2000 13:51:43 -0500
>
>A stepper is an interesting idea.  I'm assuming the control
>circuitry would be far different though.  And the linkage to the
>control pin would be complex and/or hard to fabricate, with gears
>probably involved.  Actually the newer VW turbodiesels control the
>pin I am trying to control with a stepper actuator to control the
>fuel collar.  That would be a neat EFI project.  Most of those pumps
>are capable of far in excess of 150HP.  Of course that's more of a
>real EFI project, with requirments of DBW, RPM input etc.
>
>-----Original Message-----
>From: Eric Bryant [mailto:BRYANTE at ghsp.com]
>Sent: Wednesday, December 06, 2000 1:09 PM
>To: 'diy_efi at diy-efi.org'
>Subject: RE: Wierd application, hypothetical question.
>
>
> > From: justin ivan [mailto:vlkslvr at hotmail.com]
> > Subject: RE: Wierd application, hypothetical question.
> >
> >
> > I assume that maybe by voice coil actuators you mean as in
> > speakers? Either
> > way, .5 to 1" of stroke for an electormechanical solenoid
> > really is asking
> > for too much if you need any considerable force. I could dig
> > out some of the
> > charts relating to stroke vs force that I have hiding but I
> > don't see it
> > happening.
> > if it were .25 to .33 or so, you might be able to get away with it.
>
>That's the beauty of a voice-coil actuator - you get a nearly-flat force 
>vs.
>displacement curve, while a solenoid will yield some sort of exponential
>roll-off as the armature travels from the pole piece (the shape of the 
>curve
>depending on a lot of factors, of course).
>
>With a solenoid, it's often necessary to use some mechanical advantage in
>order to keep the armature in the higher-force portion of the travel.  You
>start getting non-linearities with increasing mechanical complexity (due to
>lash and so on), so this turns into a difficult motion-control problem.
>
>A voice coil may be a bit easier than a solenoid to work with, but 
>something
>like a stepper motor will give a far-greater power density, and I think 
>it'd
>be more appropriate for this application.  At least that's where I'd
>start...
>
>Eric Bryant
>mailto:bryante at ghsp.com
>http://www.novagate.com/~bryante
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