Subject: Volvo poppet forces
Date: Fri, 7 May 1999 16:17:21 -0500
From: "Gram, Marty" <Marty.Gram@mts.com>
To: "Albright, Joe" <Joe.Albright@mts.com>, "Lorenz, Josh"
     <Josh.Lorenz@mts.com>, "Strand, Dick" <Dick.Strand@mts.com>,
     "Chen, Hans" <Hans.Chen@mts.com>, "Melander, Dan" <Dan.Melander@mts.com>,
     "Kusner, Dave" <Dave.Kusner@mts.com>, "Gallagher, Steve"
     <Steve.Gallagher@mts.com>, "Saari, Byron" <Byron.Saari@mts.com>,
     "Larson, Rod" <Rod.Larson@mts.com>, "Hessburg, Thomas"
     <Thomas.Hessburg@mts.com>, "Fullen, Mark" <Mark.Fullen@mts.com>
CC: "Beduhn, Bill" <Bill.Beduhn@mts.com>, "Cohoon, Steve"
     <Steve.Cohoon@mts.com>

Poppet valve test results.  Good news.

On May 6, we ran a series of tests on the Volvo rear actuator.  In these
test we kept the main pressure below 600 psi to avoid lifting the
actuator off the floor.  We were able to flow 22000 gpm through the
valves in each direction and measure flow forces (we reached 28000 gpm
when we opened the valves fast).  The valves have a 12" diameter poppet
with a 25 sq in drive area --they are about 25% larger than the Toyota
valve.  The Volvo valves were built without a flow deflecting "nose",
and there is no insert in the center hole.  We use an LVDT to control
valve position.

Flow force measurements were consistent with the flow forces measured on
Watervliet and UCSD -- very low.  Flow force on the return valve was
about 5000 lbf (flow in the same direction as Toyota).  Flow force on
the pressure valve was about 4000 lbf.  The flow forces did not vary
noticeably with valve opening.

When we run at full system pressure of 5000 psi, we expect the flows to
increase by a factor of 3 and expect the flow forces to increase by the
same factor.

Joe:  It may be worthwhile to revisit the Toyota valve flow force
measurements.  Could the very high forces that you measured on the
poppet be due to something other than flow force? -- acceleration?
--effect of a loose LVDT?  --vibrations on the transducer?  --pressure
taps seeing a venturi effect?

--Marty
