September 15, 2015
KS Kolbenschmidt
Less weight, less friction: the newest-generation Liteks gasoline engine pistons
In recent years,KS Kolbenschmidt has repeatedly refined its Liteks design for ultra light and, at the same time, durable gasoline pistons. Compared to todays in-productionpistons, the latest design is another 10 percent lighter. Friction is minimized and, consequently, fuel consumption and emissions are down, too. There is also a high-performance variant ofthese newly designed pistons. This comes complete with piston ring carrier and coolant passage and is intended for very high-power gasoline engines.
Past years have seen the development of the fundamental design of the Liteks pistons and now, as a consequence of the newly configured skirt support, it has been possible to achieve a more homogenous stress distribution in the piston itself as well as further enlarged ring zone undercuts. The fourth-generation pistons again show a marked reduction in weight while nonetheless being able to cope with the very high thermal and mechanical loads imposed by today's power units.The new designespecially caters forfuture direct-injection and multi-turbo engine technologies: the convex pin boss abutting surface hub in conjunction with the newly configured connection to the piston skirt provides for well-balanced piston crown support which, in turn, better distributes strain concentration over the entire combustion surface.
The new Litekspistons will make future engines more efficient. The pistons themselves owe their weight reduction to alloy KS 309 and the design engineers' consistent exploitation of this material's specific advantages. Thus the wall thickness of the piston crown was reduced by up to 30 percent. The increased size of the ring zone undercuts is made possible by an optimized casting tool design.
Demonstrable friction improvements
On the fourth Liteks generation, friction has again been lowered by fine-tuning the basic piston structure and optimizing piston profile, which is asymmetrically barrel shaped. On the thrust and anti thrust sides, differing and variable ovalities have been used along the skirt height. Skirt width has also been reduced. As a result, friction is now down by28% under full-load conditions and 7% under part load. The new Liteks generation thus contributes significantly to reducing CO2 emissions from modern gasoline engines.
Nanofriks skirt coating reduces friction and wear
Another benefit comes from the Nanofriks skirt coating developed by KS Kolbenschmidt. A combination of nanoparticles, solid lubricant, and additives, this coating reduces possible mixed friction losses while wear behavior is still improved. Tribological investigations demonstrate that, compared to conventional coatings, Nanofriksshrinks both the dry friction coefficient and wear by over 50 percent and thus addresses the requirements of today's engines regarding fuel efficiency as well as operating dependability. Meanwhile, Nanofriks coated pistons are being used by leading OEMs worldwide—in future also in combination with fourth-generation Liteks pistons.