camless engine

[Greg Hermann]

>>
>
>Thanks for the break Grumpy.
>
>I was just throwing the powerstroke idea around as a starting point. My
>thoughts had
>no respect for the laws of physics. But how about a solenoid controlled
>valve to
>allow high pressure fluid into a hydraulic ram that opened the valve. A
>position
>sensor on the valve somewhere and an identical set-up to slow the opening
>and then
>close the valve.
>Similar to the Ducati desmo gear set up where the camshaft opened and
>closed the
>valves( I have no idea how to spell desdromonic and my spell checker
>fainted when I
>tried)
>
>Neil
>
Long ago, had the fun of talking to a guy who had worked for Thompson Valve
(now the "T" in TRW) about the hydraulic pressures that are encountered in
hydraulic (self-adjusting) lifters. These are not only the sort of
pressures you would be dealing with, but trying to switch on and off and
start and stop the flow--consider the inertia in the fluid itself, as well
as the weight of the valve. They are easily comparable the the higher range
of diesel fuel injection pressures--2000  BARs!! (About 30,000 psi).

Not saying it is not possible, just not too likely any time soon.

Variable valve LIFT is not to important. Variable valve timing and duration
has a LOT of potential. As is already being done, the most likely
practical way of achieving it is with hydraulic/mechanical adjustment of
the cam timing, and possibly next with multiple cam lobes per valve.
Variable lift can be achieved on a practical basis with variable rocker
geometry--and this is already being done, although not on a mass production
basis.

I strongly suspect that all the talk about 32 V. solenoids is directed more
toward controlling the actuation of this kind of hardware, and possibly
toward control over variable inlet tract geometry (which is also already a
reality) than toward actual hydraulic actuation of the valves themselves.

The good old fashioned poppet valve is a VERY well developed and durable
part, and it flows far better, particularly for intermittent flow, compared
to other schemes than a lot of folks give it credit for!

Back to our regularly un-scheduled efi programming---

Greg


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