The wearing failure mechanism and optimization of diesel engine piston pinhole with copper bushing under ultra-high cylinder pressure

This paper investigates the wear issue of the piston copper bushing pinhole in diesel engines under ultra-high cylinder pressure and analyzes the wear mechanism of the copper bushing pinhole after engine testing. A thermo-mechanical coupling simulation model of the piston assembly is established, and the accuracy of the simulation model is verified by experiments. Meanwhile, taking the coefficients and exponents of the segmented function profile as research objects, and aiming at the peak contact pressure of the copper bushing pinhole as the optimization goal, a segmented function profile design method for the copper bushing pinhole is proposed. The results show that the wear of the copper bushing pinhole is mainly characterized by the synergistic wear of abrasive and adhesive wear. The exponent and coefficient of the inner function of the segmented function profile and the length of the transition section have a greater impact on the peak contact pressure, while the influence of the exponent and coefficient of the outer function is relatively small. The optimal segmented function profile obtained reduces the peak contact pressure of the copper bushing pinhole by 20.3%. This method has a good optimization effect and provides a theoretical basis for the design of the copper bushing pinhole profile under ultra-high cylinder pressure in the later period.