Research on lightweight design method of diesel engine steel piston based on heat transfer characteristics

Steel pistons are gradually replacing traditional aluminum–silicon alloy pistons as the preferred choice for high-power density engines. However, there is still a lack of systematic research on the heat transfer characteristics of steel pistons in the field of small bore diesel engines. For this reason, this paper was based on the storage temperature testing system to study the variation of temperature field and thermal stress in steel pistons of the small-bore diesel engine under the maximum torque conditions. The results show that there are significant temperature variations in the circumferential path of the steel piston head, indicating that the temperature distribution of the steel piston is highly uneven. The highest temperatures and maximum thermal stresses were found in the rim. To further achieve the lightweighting of the steel piston, a lightweight design method based on heat transfer characteristics was proposed. A multi-objective optimization algorithm was used to optimize the top land height and the position and shape of the cooling gallery. The structural design solutions with volume and thermal stress control were finally obtained. The optimized design solution can reduce the mass by a maximum of 10.01 %, the maximum temperature by a maximum of 35.04 °C and the maximum thermal stress by a maximum of 18.38 % compared to the original design.