Electronic valve control

[Christopher G. Moog]

Tony Cooper wrote:

> > delsol wrote:
> > > Has anyone had any experience with electronic control of  engine valves?
> > > Ideally no cam would be involved. Any ideas or info, anyone?
> > > Daniel

Several systems have been proposed.  Current firm pushing this idea (for several
years mixed results) has been Aura Systems in California.  They use two valve
springs (one above the valve stem pushing open and one in the normal position
pushing closed).  When no power is applied the valves stay half open.

The system uses two solenoids one to hold the valves open and one to hold them
closed.  The springs store the initial energy of closing the valve to reopen
them.  It works like this.  At start-up the valve closing solenoids are
energized closing all the valves (relatively large amounts of current are needed
to pull the valves closed).  With the valves closed the voltage applied to the
closing solenoids can be cut back since the valve need to held closed rather
than pulled closed.  The hold closed solenoids are selectively turned-off.  This
causes the springs to open the valve.  The momentum of the moving valve causes
it to overshoot the neutral position and go to the fully open position.  The
hold open solenoid is energized to hold the valve in the open position.  To
close the valves the process is reversed.  This cuts down the energy needed to
open and close the valves since the solenoids are holding the valves in position
rather than moving them.

Aura has been pushing the technology for several years.  I believe they have
demo'ed the system on several engines (Ford OHC 2.3 Pinto, GM 3.8 liter V-6) but
have not, as of yet, interested an auto maker in the technology.  I've heard the
system works best with 2 valve heads (costs lower, greater potential pay back)
and is limited in the RPM (less than 6,000) under which it can operate.  I
believe someone on this list is working on a set-up for a Chevy Small Block.
Should be interesting.