|The new Advanced Elastoval II piston. Click to enlarge.|
Federal-Mogul Corporation has developed a lightweight, high-strength aluminium piston that enables engine manufacturers to increase the power density and efficiency of boosted, direct injected gasoline engines. The Advanced Elastoval II piston enters series production later this year in a new European passenger car, where it contributes to gains in fuel economy and reductions in CO2 emissions.
Specific power outputs in engines are likely to increase from current levels of around 95 kW/L to 130 kW/L to coming years. Peak combustion pressures will rise from 110 bar to 130 bar and even 160 bar in engines using alternative fuels such as E100, compressed natural gas (CNG) or others, Federal-Mogul notes.
|Cutaway of the Advanced Elastoval II piston. Click to enlarge.|
The new Advanced Elastoval II piston is lighter, delivers increased power outputs and can withstand the higher pressures that occur late in the combustion cycle of highly charged downsized engines.
The Advanced Elastoval II piston architecture is up to 20% lighter than previous generation pistons. Whereas previous wall sections measured 4mm, the latest piston achieves wall sections as thin as 2.5mm.
Any reduction in wall thickness requires the entire piston structure to be redesigned. Advances in piston design, analysis tools and testing at Federal-Mogul’s global development centers have led to a series of new features that achieve a better stress distribution, enabling a weight optimized design.—Arnd Baberg, chief engineer product engineering, Federal-Mogul Powertrain Energy
The complex curved side panel forms of the Advanced Elastoval II piston are inclined in two planes and are closer together at the top to support the piston crown, using multiple weight-reducing pockets and crown reinforcing ribs. The piston pin bosses are curved towards the side panels and boss distance is reduced to the minimum possible. The piston’s design uses asymmetric geometries to enable maximum weight reduction.
All Federal-Mogul Elastoval pistons use different skirt widths for the thrust and non-thrust sides of the piston, to achieve the best compromise of light weight, superior NVH and scuffing performance.
Advanced Elastoval II reduces skirt width to 50% of bore diameter on the thrust face and just 45% of the bore on the non-thrust face without compromising NVH or increasing scuffing risk.
Several vehicle manufacturers are validating the Advanced Elastoval II piston, with the first scheduled for series production later this year.