24.05.2009 NEW FPT MULTIAIR SYSTEM BEGINS PRE-PRODUCTION AHEAD OF AUTUMN DEBUT

FIAT MULTIAIR
ALFA MITO 1.4 MULTIAIR
FIAT MULTIAIR

Fiat Powertrain Technologies' innovation new Multiair electro-hydraulic valve actuation system (top and bottom) will make its first ptoduction application this autumn in the Alfa Mito (middle).

Fiat Powertrain Technologies (FPT) has started manufacturing of the 1.4-litre FIRE engine incorporating the ground-breaking new Multiair electro-hydraulic value actuation system ahead of its introduction into Fiat Group Automobiles' production models starting from September. The news that Multiair pre-production is now getting underway at FPT's key Termoli plant at Molise in Italy comes from the Milano Finanza newspaper.

Termoli is one of FPT's key factories and currently produces the 1.4-litre FIRE engine, in 8v and 16v formats, as well as manufacturing Fiat's C510, C513 and C546 transmissions. The highly advanced Multiair system was officially presented during a press conference at the 79th Geneva Motor Show in March, and its first application will be on the Alfa Romeo MiTo in the autumn. It will be initially fitted to a range of 1.4-litre engines with power outputs from 105 to 170 bhp before being rolled out to a number of other FPT range engines next year, including the forthcoming 900c SGE (Small Gasoline Engine).

Alongside Multiair, FPT will also introduce its Multijet 2 technology later this year on the acclaimed 1.3 SDE. The new technology, focusing mainly around developments in pump and injector technology, will boost the engine's outputs from the current 90bhp and 200Nm to 95bhp and 230Nm, and is expected to debut in the Lancia Musa before also appearing in the Fiat 500.

Multiair is a new 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 reducing fuel consumption; pollutant emissions are likewise reduced through combustion control Multiair is a versatile technology, easily applicable to all gasoline engines and with future potential developments also for diesel engines.

The multiple benefits of the Mutiair system start with an increase of maximum power by up to 10 percent thanks to the adoption of a power-oriented mechanical cam profile. Low-rpm torque is improved by up to 15 percent through early intake valve closing strategies that maximize the air mass trapped in the cylinders. Elimination of pumping losses brings a 10 percent reduction of fuel consumption and CO2 emissions, both in naturally aspirated and turbocharged engines with the same displacement. Multiair turbocharged and downsized engines can achieve up to 25 percent fuel economy improvement over conventional naturally aspirated engines with the same level of performance. The Multiair system also offers optimum valve control strategies during engine warm-up and internal exhaust gas recirculation, realised by reopening the intake valves during the exhaust stroke, result in emissions reduction ranging from 40 percent for HC / CO to 60 percent for NOx.

The operating principle of the Multiair system, applied to intake valves, is the following: 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 the solenoid 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 hydraulic chamber and the intake valves are de-coupled; the intake valves do not follow the intake cam anymore and close under the valve spring action. The final part of the valve closing stroke is controlled by a dedicated hydraulic brake, to ensure a soft and regular landing phase in any engine operating conditions. Through solenoid valve opening and closing time control, a wide range of optimum intake valve opening schedules can be easily obtained. For maximum power, the solenoid valve is always closed and full valve opening is achieved following completely the mechanical cam, which was specifically designed to maximise power at high engine speed (long opening time). For low-rpm torque, the solenoid valve is opened near the end of the cam profile, leading to early intake valve closing. This eliminates unwanted backflow into the manifold and maximises the air mass trapped in the cylinders. In engine part load, the solenoid valve is opened earlier causing partial valve openings to control the trapped air mass as a function of the required torque. Alternatively the intake valves can be partially opened by closing the solenoid valve once the mechanical cam action has already started. In this case the air stream into the cylinder is faster and results in higher in-cylinder turbulence. The last two actuation modes can be combined in the same intake stroke, generating a so-called “Multilift” mode, that enhances turbulence and combustion rate at very low loads.
 

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