Subject: Servovalve Erratic Behavior
Date: Wed, 7 Apr 1999 14:43:40 -0500
From: "Albright, Joe" <Joe.Albright@mts.com>
To: "Chen, Hans" <Hans.Chen@mts.com>, "Anderson, Harlan"
     <Harlan.Anderson@mts.com>
CC: "Gram, Marty" <Marty.Gram@mts.com>, "Saari, Byron"
     <Byron.Saari@mts.com>, "Larson, Rod" <Rod.Larson@mts.com>,
     "Nelson, Terry" <Terry.Nelson@mts.com>, "Melander, Dan"
     <Dan.Melander@mts.com>, "Lorenz, Josh" <Josh.Lorenz@mts.com>

Hi Hans/Harlan,

While testing the Toyota Crash Simulator, we believe we are seeing short
periods of time during a pulse where the 256 spool position moves in an
unexpected direction for a short distance, and then catches back up with
the expected position.  It may have been doing that for an extended
period of time.  We are not certain.  It became very evident recently
during a higher jerk test because the unexplained motion occured right
at the time of poppet unseating, creating a very large acceleration
transient.  I am interested in any ideas you (or any of the cc's) might
have about why it occurs and how to remedy it.

Byron and I have started investigating possible control output errors
from the model, and will probably change pilot valves to see if it is
pilot specific.  One possible explanation proposed was 252 ball slop.
If that is indeed the case, an electric feedback pilot valve would
address that problem.  Along those lines, what is the status of the
Bosch valve with electric feedback we evaluated a year or so ago.
Harlan, I was unsuccessful finding it in the back room.  Do we still
have it, and if so what is the pressure rating on the valve and what is
required to try it on our system?

Any ideas anyone would care to share would be greatly appreciated.  At
the moment, this problem is proving to be a bit of a show stopper.

Thanks!

Joe A

joe.albright@mts.com
http://intranet.mts.com/users/a/albright/index.htm
X4355
MIPS Dept (
http://intranet.mts.com/users/b/bigotB/reference/mips/index.htm )
Toyota Crash Sled
(http://intranet.mts.com/users/a/albright/1997/CrashSim/Checkout/DailyLo
g.htm)
