The Free Valve concept, also known as continuous variable valve timing, offers the ability to have independent control of the intake and exhaust valves in an Internal Combustion Engine. For any engine load criteria, the timing of intake and exhaust can be independently programmed. The engine can then “decide” based on driving conditions which one to use to maximize performance. This allows a greater degree of control over the engine which in turn provides significant performance benefits.
- While the concept has been widely tested, no manufacturer has been able to implement it in large scale production due to various technical problems along with the higher cost.
- Traditional Free Valve engines use either electro-magnetic, electro-hydraulic, or fully mechanical actuators to open the poppet valves. Instead of using these traditional actuator types, Cargine uses electro-hydraulic-pneumatic actuators combined with advanced sensor techniques. As a result, Cargine has overcome all of the typical challenges faced by other Free Valve techniques.
- The system has a verified fuel consumption reduction of 12-17 percent compared to a state-of-the-art four cylinder two liter engine with Direct Injection and variable cams. Energy consumption investigated and concluded same as for cam system in normal rpm range. The tests were performed on a single cylinder engine at AVL in 2011.
- The system has been successfully tested and installed in a SAAB 9-5 (intake valve only) from 2009 to 2011. Over this time period, the SAAB has driven more than 55,000 Km of everyday driving and proven start ability down to -20 degrees Celsius.
- The expected timeline from an automotive OEM commitment to mass production is 12-18 months, depending on the commitment.
Source: Cargine
Romain’s opinion:
I believe in such a technology which is close to the Fiat Multi-air system. However, it seems that it needs a compressed air source for the pneumatic actuation. In trucks, this is not a problem because an air compressor is often fitted on the engine but in passenger cars, it may need extra components to generate this pressurized air. When do you think this free valve technology could be ready for serial production?
