With the constant talk of electric vehicles being the next big thing, it’s interesting to see how much development is still being done on the good old internal combustion engine, the Fiat MultiAir engine is a good example.
The Fiat MultiAir Engine, uses a solenoid valve to control oil flow to a hydraulic lifter that actuates the intake valve. The mechanical cam actuating the valves uses a high performance profile. During periods when high performance operation is necessary, the solenoid valve is closed, the hydraulic lifter is locked in place and the mechanical cam is followed yielding maximum performance. During all other periods, from warmup to idling to low speed and everywhere else in between and all through the rpm range, the solenoid valve can be opened at varying times for varying durations to give exactly the engine performance required.
The intake valve, when not directly coupled to the cam, closes using spring pressure with final closure controlled by a dedicated hydraulic brake which ensures a precise soft landing.
Valve control within each stroke
The solenoid valve can vary within each piston stroke, allowing the cam to begin opening the valve early, for instance, then partially allowing oil to flow to keep the valve from opening as far as it otherwise would if following the cam profile exactly. This process allows precise, cylinder by cylinder air flow control to give just the right performance called for with the lowest emissions possible.
Applicable to multiple engine types and fuels
Since this technology applies to valve opening it’s widely applicable, it can be used in both spark ignition and diesel engines, normally aspirated or forced induction and with a variety of fuels.
25% better fuel economy and lower emissions
Fiat points to a 25% increase in fuel economy due to greatly increased engine efficiency allowing smaller engines for the same power output plus:
Optimum valve control strategies during engine warm-up and internal Exhaust Gas Recirculation, realized by reopening the intake valves during the exhaust stroke, result in emissions reduction ranging from 40% for HC / CO to 60% for NOx
First application of the technology will be on a 1400cc 16 valve 4 cylinder and then a 900cc 2 cylinder, the sort of engine sizes you might find in a motorcycle. Hmm …
The precise control now possible of what was once an almost purely mechanical function means the internal combustion engine has a long way to go before it leaves the scene and most of us around here, I think, are pretty happy about that. Very neat technology, I like it!