Fiat Group and Fiat Powertrain Technologies took advantage of the event to unveil its new Multiair air management technology. The system is an electro-hydraulic system of engine valves for dynamic and direct control of air and combustion, cylinder by cylinder and stroke by stroke. Thanks to a direct control of the air through the intake engine valves without using the throttle, Multiair helps reduce fuel consumption and engine emissions.
The operating principle of the system is as straight forward as it gets. A piston, moved by a mechanical intake cam, is connected to the intake valve through a hydraulic chamber, which is controlled by a normally open on-off Solenoid Valve.
When this valve is closed, the oil in the hydraulic chamber behaves like a solid body and transmits to the intake valves the lift schedule imposed by the mechanical intake cam. When the solenoid valve is open, the decoupled hydraulic chamber and intake valves close under the valve spring action.
Technical details aside, Multiair was developed because of its benefits. The system allows for low rpm torque to be reduced by 15 percent and improve the dynamic engine response. Multiair's strongpoint reside in its ability to reduce fuel consumption and CO2 emissions.
Turbocharged engines fitted with the system can achieve up to 25 percent fuel economy over naturally aspired engines with the same level of performance. Together with the internal exhaust gas recirculation system, CO2 emissions are reduced by 40 to 60 percent.