This invention deals with an electronically controllable Variable Valve Lift System for internal combustion engines.
This system is a mechanical transmission having the capability of varying the lift of the intake and/or exhaust poppet valves while the engine is running and when varying its working conditions. Said variations being continuous and within wide limits.
The mechanical transmission includes (see Fig. 1) a regulator mechanism (RM), with two slotted holes (10), and an actuation mechanism composed by:
- a primary oscillating lever or finger follower (3), in contact with the cam (1) actuating the lift of the valve;
- a secondary oscillating lever or finger follower (4), directly acting on the poppet valve (6);
- a wedge-shaped slider device (5), with a bore fitted with a roller free to rotate and having its ends protruding from it. The ends of said roller are engaged and guided by the slotted holes (10) of the regulator mechanism. Said slider is interposed between the two oscillating levers and transmits the movement from the primary oscillating lever to the secondary one. Said slider, by sliding back and forth during the valve’s lift, actuates – depending on the rotation of the regulator mechanism around the axis C – the variation of the poppet valve’s maximum lift.
The regulator mechanism is operated by a suitable system (e.g. an electric engine driving a worm gear) in order to modify – according to the engine working conditions and to the defined engine regulation strategies – the angular position of the slotted holes and hence the movement of the slider, when the cam is lifting, with respect to the two oscillating levers, in such a way actuating the variation of the transmission characteristic from the cam to the poppet valve (see Fig. 2).
For a complete description of this invention and the registered patents, look at the link:
The primary application of a VVLS like this one is for maximizing the volumetric efficiency of the engine over the speed (maximum torque/power vs. revs), which is physically impossible with a fixed lift of the valves. This gives also the chance of downsizing the engines, which is one of the most effective ways to reduce both fuel consumption and emissions.
The description of the other applications and benefits would ask for more space than allowed here. Full details available at the above mentioned link.
Finally, it is worth to be mentioned that the merging of FIAT with Chrysler is also based on the transfer of innovation from the Italian Automotive Manufacturer. The most important one no doubt being represented by the electro-hydraulic MultiAir Variable Valve Lift System (original FIAT’s Patent), which is going to be introduced in the Chrysler engine line. This further demonstrates that this solution represents the most effective way to improve the performance and reduce both the fuel consumption and the emissions - including CO2 - of current internal combustion engines
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