In a conventional valve control system, the cams of the rotating intake camshaft open and close the valves. The air required for the combustion process is controlled by the position of a throttle valve. The main disadvantages of this system are energy wastage and slow adjustment to the continuously changing driving conditions.

In the UniAir system, the intake valves are not controlled directly by the intake camshaft, but indirectly via intermediate hydraulic chambers. These chambers open the valves by means of oil pressure. If this pressure is discharged by a controlled solenoid valve, the intake valve will not open even if the cam is in the lift phase.

In an example of potential, a newly-developed Jaguar Ingenium four-cylinder gasoline engine series features the UniAir system combined for the first time with two hydraulic camshaft phasing units.

The additional degree of freedom offered by the system with its optimized mass design means that the engine can operate in an even broader spectrum of the data map with optimum efficiency. This means, for example, that the engine can be switched off in start-stop operation and can be started again at lightening speed keeping vibrations in both instances to a minimum.

Another advantage of the technology is the fast and precise control of the valves to match the relevant cycle. This allows an instant increase in torque without impairing the efficiency of the engine due to the significant retardation of the ignition timing.

With the Jaguar Land Rover Ingenium gasoline engine, we have successfully completed the first stage on the way back to producing our engines in-house. The close collaboration with Schaeffler has made a significant contribution here. The engine scores points with its outstanding driving behavior, excellent performance, and reduced fuel consumption.

—Ron Lee, Powertrain Director in the Development department at Jaguar

From the finger follower through to the fully-variable UniAir valve control system, Schaeffler offers a modular system for variability in the valve train. Complemented by decades of experience in vibration damping, a high level of driving comfort is also guaranteed in demanding operating modes. Optimum interaction between the technologies is a decisive factor for ensuring further reductions in fuel consumption and emissions.

We are continuously developing UniAir technology in oder to meet the increasing demands of our customers to produce drives that reduce fuel consumption and emissions. Since its development, market interest in the system has steadily increased. The fact that other automobile manufacturers are now using this innovative technology provides us with a source of recognition and of motivation to continue along this path.

—Prof. Peter Pleus, CEO Automotive Schaeffler AG