Electronic valve control

[BUTLER, Tom]

> -----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