Valves are by far one of the most simple concepts on a motor vehicle. Advances in valve technology have existed since the 1980’s however without the development allowed in top level motorsports, standard valve technology has remained to this day.
There are a few companies however out there which have tried new things, during the 1990’s an Australian company developed a rotary valve system for formula 1 racing, however the rules were changed before it could be introduced, making standard valves enforced across all FIA racing categories.
Recently however the need for new valve technology, in terms of reduced emissions, has seen private and non racing development of new valve technology systems, the main of which has become known by the company name FreeValve. FreeValve is developed in Sweden alongside Koenigsegg who will be introducing the system into their road cars within the next 5 years.
FreeValve systems incorporate air pressure to open and close each individual valve, the benefits of this system is that a computer will control when each valve will open and close, doing away with the inefficiency seen in Camshafts and removing the need for timing belts / chains, making the engine smaller and lighter weight.
Air valve systems incorporate either an oiled mechanical spring to close, or an air spring. The benefits of the mechanical spring is that if air pressure is lost in the top of the valves opening system, the valve automatically shuts, leaving no damage to the engine. Air springs on the other hand, require the input of air below the piston of the top air supply, meaning they will only shut with the addition of air below the piston, potentially causing engine damage if air pressure is lost.
Mechanical springs however, are known to be fairly unreliable, if they were to break then the same situation would be seen as the air springs failure. For this reason most prefer using air to both open and close the valves. In reality however, a combination of both may present in the final product, with the mechanical spring being used at lower pressures, incorporating air pressure to close, and leaving the mechanical spring as a secondary back up system to prevent engine damage.
The benefits of independent valve systems such as the FreeValve system means that the inlet of fuel can be perfectly controlled, the best method of fuel delivery is via an on and off fashion, something impossible with a camshaft, as a camshaft will need rotating force to open and close, and while cam lobes can be machined for a slight increase, nothing beats the ability to simply open and close a valve on demand for perfect fuel delivery.
In the same way, exhaust gasses require the same method to completely empty the combustion chamber, this leaves the cylinder clean of any excessive heat and gases which will cause problems with the next combustion cycle, thereby increasing fuel efficiency by keeping the cylinder in better condition in regards to the atmosphere inside the cylinder itself.
Tests have shown around a 30% increase in power, 30% increase in fuel economy, 30% more torque and 50% reduction in emissions using the freevalve system on a regular road going engine. When combined with further technology such as Mazda’s SkyActiv, which is essentially a diesel engine system using petrol to significantly lower fuel usage, the overall reduction compared to a regular medium range compression standard valved piston engine in terms of emissions could be around the 65% to 70% mark, with further increases in torque, power and fuel efficiency.
Furthermore, these systems can carry over without modification in the event of a rise in popularity of hydrogen fuel systems, something which has recently been shown to be viable when extracting methane from mining operations, a new technique allows extractions of methane to leave behind only pure hydrogen and high quality pure carbon, making the ability to end LPG production and switch to hydrogen a cheap and reliable option for the future.