This solution was first introduced Renault in the Formula 1. The idea is simple: replace the screw spring cylinder (22) and piston (20) moving together with the valve. The residue of the timing system (rollers, cams, etc.) have not changed. In the cylinder there is a compressed gas (28), usually nitrogen that is compressed when opening the valve (4).
A heavy steel spring was removed in this way. The stiffness of the gas spring can be increased almost indefinitely, without increasing its size. The main limitation is only the quality of the seals.
A certain inconvenience of such timing is to fill the cylinders before starting the engine. Currently, pneumatic springs use all bands F1.
The period of the greatest popularity of this solution has already passed. Mercedes used them in 50,000
Ducati desmodromic timing [/18] [19] The concept is based on complete removal of springs and the use of additional valves closing levers. They work with dedicated cams. The almost perfect solution can work at very high rotational speeds, and at the lower ones, it does not waste energy to compressing excessively rigid springs.
Unfortunately, it's easy to see that this is a complicated and difficult circuit. Currently, the only manufacturer applicable to the desmodromic timing is the manufacturer of Ducati motorcycles. Even Japanese competition from Motogp headed towards gas springs.
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