Electronic valve control

[Shannen Durphey]

BUTLER, Tom wrote:

> > -----Original Message-----
> > From: Clare Snyder [SMTP:snyder at huron.net]
> > Sent: Monday, February 09, 1998 9:14 AM
> > To:   diy_efi at efi332.eng.ohio-state.edu
> > Subject:      Re: Electronic valve control
> >
> > dzorde wrote:
> > >
> > > I think you would eventually break the valve from the stem due to
> > the sheer
> > > hammering of the valve against the seat.
> > >
> > > Dan     dzorde at geocities.com
> > >
> > > >Actually there have been a few engines built and run with solenoid
> > controlled
> > > >valves........however they are VERY noisy, this is because as the
> > solenoid
> > > >begins to close the valve it accelerates considerably resulting in
> > slamming
> > > >the valve in its' seat whereas a cam actutated valve will be placed
> > on its'
> > > >seat with zero velocity. I have heard that the solenoid engines
> > sound alot
> > > >like diesels....
> > > >
> > > >Scott Shotton 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
> > > >>
> > > >> This idea has crossed my mind before.  Computer controled valves
> > would
> > > >> be an invaluable tool.  Infinate duration and timing
> > posibilities.
> > > >> However, as far as I know, solenoid technology is not good enough
> > for
> > > >> that particular application.  I wish it were!
> > > >>
> > > >> Scott
> > > >
> > > >
> > > >
> > > >
> > What about hydraulic or pneumatic control, with computer controlled
> > solenoid control of the fluid system?
> > --
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>         The problem here is that you need the engine running in the
> first place in order to have hydrualic pressure or pneumatic pressure to
> actuate the valves.  You have a chicken and egg problem.  While it is
> possible to have some sort of reservoir to hold pressure, you still have
> to worry about pressure leak-down.  Even if your seals are perfect, what
> about a hard starting situation?  How much reserve capacity must you
> have?  Some arrangement might be made to pump up pressure in an engine
> non-start situation, but compexity is going way up.  Solenoid actuation
> seems to me to be the only viable avenue of pursuit.  I don't dislike
> cam shafts enough to want to cause myself that much brain damage
> however.
>
>         Tom Butler  TEBUTLER at MCCAIN.CA

  I guess my earlier post never made it through.  One way to do this would
be to control the lifter bleed down rate.  If the cam had a high lift/long
duration lobe, then the bleed off could be held to a minimum during the
earliest part of the lift, and then dumped before the valve is open too long
to create early valve timing and lift.  As RPM increases, this could be
reversed.  If the lifter were made such that it had a minimum mechanical
lift then it would always open the valve no matter how much fluid pressure
there was within the lifter body.  In current engines, this could give a
rough form of valve control by using lifters with a fixed bleed down rate
and controlling the supply pressure.  Crude, but still better than fixed
lift and duration.

Shannen