8 replies to this topic

[Nustang70]

i am not even sure if that is how you spell it:rolleyes:
can someone please inform me? also, what did they use before Renault introduced pneumotic valves?

[Ursus]

It means you use pneumatics(pressurised air/gas) instead of metal springs to close the valves.

[Rainer Nyberg]

The valves have a pneumatic return. The pneumatic system is used instead of the 'normal' coil spring return of the valves.
The pneumatic valve return allows higher engine revs.

The other - rarely used - system is desmodromic valves, where the valves are both opened and closed mechanically.

[MacFan]

The performance of metal springs was previously the limiting factor in the quest for higher revs. Replacing them with a pneumatic system using compressed air has allowed the very high revs now used in F1.

[DVRNT]

Two more facts about springs;

Neumatic springs have less reciprocating mass, so they can open and close faster than metal valve springs.

Metal springs vibrate when they are closed, that can cause valve bounce, this is another limiting factor. .

[marion5drsn]

I’ve been perusing this question for a few hours and it gives me a good opportunity to correct several terms used by myself and many others about the phrase ,”pneumatic valves”.
Firstly there is no such thing as a pneumatic valve as the term is used by many! The term should be more accurately a gas spring.
Secondly the term pneumatic as used really means a replacement of the helical metallic spring by a air spring. Others gasses can be used but for what purpose I don’t see any necessity. Dry nitrogen could be used but at the pressures used the water vapor should not turn to steam. Would it make any difference in any case?
Thirdly, metallic springs are subject to, coil bind, spring fatigue, spring surge, valve float and a lot of other unfavorable occurrences that air springs are not subject to. Most of these are due to the fact that metallic springs are a great deal like the strings on a bass violin that is they vibrate and have natural frequencies, standing waves, beats and overtones. Mercedes understood this as far back as 1939 when they produced the 1.5 Liter GP engine.
Fourthly the word pneumatic is an unnecessicarily lengthy word. How many of us use the phrase pneumatic compressor, I believe the most used term is air compressor.
There is a diagram at http://www.atlasf1.c...40&pagenumber=3
M.L. Anderson

[Top Fuel F1]

Here's a direct hyperlink to the diagram Marion is talking about:

http://www.atlasf1.c...8948#post488948

[desmo]

Here's the image.

Good points Marion. Perhaps just saying air spring would be less confusing. People have a tendency to think of pneumatically actuated valves rather than simply pneumatically sprung ones when they hear the term 'pneumatic valves'.

[Nustang70]

thanks to everyone who tried to help.