Subject: RE: Servovalve Erratic Behavior
Date: Thu, 8 Apr 1999 06:33:01 -0500
From: "Anderson, Harlan" <Harlan.Anderson@mts.com>
To: "Albright, Joe" <Joe.Albright@mts.com>, "Chen, Hans"
     <Hans.Chen@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>

Joe
Are there G forces going with the motion of the pilot spool? I recently
took some plots which show some of the effects. If that helps.
I did find the Bosch valve if you want it.

                -----Original Message-----
                From:   Albright, Joe
                Sent:   Wednesday, April 07, 1999 2:44 PM
                To:     Chen, Hans; Anderson, Harlan
                Cc:     Gram, Marty; Saari, Byron; Larson, Rod; Nelson,
Terry; Melander, Dan; Lorenz, Josh
                Subject:        Servovalve Erratic Behavior

                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)


