LIGHT WEIGHT PISTONS FOR FRICTION OPTIMIZED SPARK IGNITION ENGINES

This article describes the development of MAHLE piston technology with the goal of meeting increasing requirements of advanced, highly efficient gasoline engines. The new EVOLITE (R) lightweight piston from MAHLE is a continuation of the development of its predecessor, the EVOTEC (R) 2, and is based on the EVOTEC (R) design concept. This concept differs from the design approach of previous decades in that the piston geometry has inverted asymmetry on the thrust and antithrust side. A narrow thrust side is combined with a wide, elastic antithrust side for skirt guidance. The light, robust EVOTEC (R) 2 piston is available with ring carrier or cooling gallery - Figure 1. The EVOLITE (R) concept represents further refinement of the EVOTEC (R) design concept by increasing asymmetry further. By geometrically optimizing the box wall connection between the skirt and crown, the lifetime has been increased by up to 8 times in comparison with the EVOTEC (R) 2, depending on stress location, while the weight has been reduced by up to 5%. Friction, which is critical for low CO2 emissions, is also reduced with this new piston type.