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In the 2006 Formula 1 World Championship the rules allowed for pneumatic valvesprings.

These engines were required to have a 90° V8 engine with 2.4 liters of displacement, 4-valve-per cylinder layout with two overhead cams per cylinder bank and pneumatic valvesprings.

Some of these engines were exceeding 20,000 RPM's at the end of the season. Driving the reciprocal weight of a poppet valve at 20,000 RPM's is absolutely astonishing and from the outside looking in seems almost impossible.

My Question

How did the F1 engineers design these valves to function?

They were required to run cams so this wasn't a camless solution.

How did the cams interact with the pneumatic valve springs?

Did the engine drive a pneumatic pump that provided air pressure or did they need to fill an air tank much as the CART series team had to do with their pneumatic valve solution?

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Regular valve springs won't cut the mustard in F1

That's why pneumatic valve "springs" have no springs.

Instead, they use a chamber of pressurized nitrogen to return the valves back into the "closed" position after the cams have run their course.

The diagram below (from this webpage) shows a comparison of regular valve springs on the left to the pneumatic setup on the right. The pressurized chamber is marked on the third diagram as "121".

Valve Spring Comparison

Operation

  • Valve Opening

    The cams are nothing special; they operate the valve using a bucket-shim or cam-follower design, so the valves would move down just like it would in a road-going passenger vehicle.

  • Valve Closing

    In lieu of springs, the valves are pushed into their closed position using nothing but high gas pressure.

    The webpage also mentions that when F1 engines with pneumatic valvetrains are pulled out of the engine, a remote gas cylinder needs to be connected to prevent the valves from clattering into the pistons.

Pressurized reservoir

This reservoir is likely pressurized pre-race and left alone, for a few reasons:

  • the reservoir is filled with dry nitrogen; if there was a pump that was constantly replenishing lost pressure it would introduce regular air into the system, which is undesirable.

  • running a pump off the engine is parasitic

  • if they can lose weight, F1 teams will most definitely shed it

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