Pneumatic valve train in detail

[DaveKillens]

Another factor to consider is heat. NASCAR engines are required to use springs, and they are known to be almost red hot at maximum RPM. Fatigue life as well as additional cooling requirements may also be a deciding factor in choosing one over another.

[xpensive]

This is a basic question but what is the advantage of pneumatic valves over spring valves is it simply that at higher rpm's they are more affectiv or is more complex than that, sorry if this is a stupid question but you good folks will be able to tell me. Thanks

Jesse

One of the original advantages was that in a pneumatic system like this, the gas-chambers are not really springs as
they are interconnected to have an almost constant total volume, why the gas-pressure is also basically constant.
This way there is no hysteresis and very little heat generation compared to a conventional spring-system.

All in all, no heat means higher valve-load is allowed and thus higher revs.

Something like this Dave?

[strad]

"Dave's not here"

[xpensive]

"Dave's not here"

As in Dave has left the building, or Dave has ceased to xist, or Dave is an x-member?

[markc]

"Dave's not here"

As in Dave has left the building, or Dave has ceased to xist, or Dave is an x-member?

As in Cheech and Chong...

[DaveKillens]

[Brian.G]

riff_raff,
looking at the F1 diagrams we have here, i notice that they have rigid cylinders for the air chamber and not diaphragms that are typical on automotive suspension air springs.

I hear ya, kinda like this one?



I have a mammoth thread in the pipeline in a day or two, so keep an eye out if anyone wants to know more,

Brian,

[ringo]

Great! just leave a link in here to your thread.

[Brian.G]

Great! just leave a link in here to your thread.

Sure will,

Brian,

[olefud]

This is a basic question but what is the advantage of pneumatic valves over spring valves is it simply that at higher rpm's they are more affectiv or is more complex than that, sorry if this is a stupid question but you good folks will be able to tell me. Thanks
Jesse

Pneumatic systems have less mass inertia, no fatigue or stress limits, reduced volume requirements, less sensitivity to structural vibrations, and reduced friction losses at high operating frequencies.

Springs have a worrisome resonant frequency unless the wire diameter and/or coil diameter is varied along the spring length. It seems the pneumatic spring could have the same problem, but the natural frequency would vary with pressure and volume, as well as being more easily tuned to a noncritical frequency

[aussiegman]

This is a basic question but what is the advantage of pneumatic valves over spring valves is it simply that at higher rpm's they are more affectiv or is more complex than that, sorry if this is a stupid question but you good folks will be able to tell me. Thanks
Jesse

Pneumatic systems have less mass inertia, no fatigue or stress limits, reduced volume requirements, less sensitivity to structural vibrations, and reduced friction losses at high operating frequencies.

Springs have a worrisome resonant frequency unless the wire diameter and/or coil diameter is varied along the spring length. It seems the pneumatic spring could have the same problem, but the natural frequency would vary with pressure and volume, as well as being more easily tuned to a noncritical frequency

This is the other big factor harmonics and resonance in the spring. Couple this with the heat generated by running at +10,000rpm and pneumatic valve actuation bring reliability and longevity advantages.

Coatings and improved metallurgy have helped, but I would expect pneumatics to continue to be used.

A hybrid spring/pneumatic camless system is being developed by a partnership between Koenigsegg and another Swedish company called Cargine which could be a very interesting development, however I doubt the rules would allow its use in F1.

[Brian.G]

Great! just leave a link in here to your thread.

http://www.f1technical.net/forum/viewto ... 27#p450327

Brian,