Subject: RE: Servovalve Erratic Behavior
Date: Wed, 7 Apr 1999 15:00:47 -0500
From: "Chen, Hans" <Hans.Chen@mts.com>
To: "Albright, Joe" <Joe.Albright@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>

Joe, Most likely it is pilot problem. Changing pilot may be the easiest
way to prove it. Bosch valve does not have 5000 psi rating as I
remember. Hans

> -----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/Daily
> Log.htm)
>
>
