Old 09-01-17, 12:26 AM
  #13  
dabac
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Originally Posted by FBOATSB View Post
Look Ma, no springs
Getting rid of the springs is not a goal in itself. The big payoff is expected from the easily variable timing.
A desmodromic valve train isn't any better at that than a regular camshaft.

Originally Posted by FBOATSB View Post
Desmodromic valve trains were hugely successful .....
Were they really?

Originally Posted by FBOATSB View Post
... in high revving superbike racing.
High revving being the operative word.
Insufficient understanding of harmonics and self-oscillation made the valves "float" instead of moving cleanly from open to shut. A minor tweak of valve mass and/or spring rate sorted it out w/o the complicated mechanics.

Originally Posted by FBOATSB View Post
Maybe a double acting push/pull solenoid could get this going in ... automobile engine.
Unlikely.
The spring isn't the problem. Valves needs to be forcibly moved in both directions. Springs exist as a short cut to get away from the double lifter/closer arrangement of the desmodromic system.
The trouble is the valve itself.
It still has mass enough to be difficult to shuttle back & forth by electro-magnetic force at the speed required by a combustion engine.

Valves operated directly by solenoids is doable as such. But it is proving difficult to get it compact enough.
High-voltage and cryo can fix it, but brings it own problems.

A lighter valve material would make it easier. Some weird ceramic with magnetic properties perhaps.

The Koenigsegg video briefly mentioned "pneumatics", so I think they're using solenoids as control valves for compressed air that becomes the force that moves the engine valves.
Originally Posted by FBOATSB View Post
a simple automobile engine.
Don't understand what you mean by that.
In one sense race engines have it easier. Less emission requirements, not much interest in doing well on partial loads etc.
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