The FreeValve concept, also known as fully variable valve actuation, offers the unique ability to have independent control of the intake and exhaust valves in an ICE. For any engine load criteria, the timing of intake and exhaust can be independently programmed. The system can then “decide” based on driving conditions which one to use to maximize performance or minimize fuel consumption and emissions. This allows a greater degree of control over the engine which in turn provides significant performance benefits.
While the fully variable valve actuation concept has been widely tested, no manufacturer has been able to implement it in large scale production due to various technical problems along with packaging disadvantages and higher cost. The FreeValve technology shows great promise of overcoming these challenges in a cost-effective way.
Previous fully variable valve actuation engines use either electro-magnetic or electro-hydraulic to open the poppet valves. Instead of using these actuator types, FreeValve uses electro-hydraulic-pneumatic actuators combined with advanced sensor techniques. As a result, FreeValve 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 DI 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 powertrain manufacturer AVL in 2011 with further potential of improvement.
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 SAAB 9-5 test vehicle has also been driven 10,000km with both intake and exhaust valves controlled by the FreeValve system.