Research on Reduction of Piston Vibration by Providing Granular Dampers Inside the Lattice Structure 2023-01-1149

Highly compression ratio is effective as one means of improving the thermal efficiency of an internal combustion engine. On the other hand, rapidly rise at combustion pressure to occur because of this high compression ratio causes a highly impulse force. The impulse force gives rise to a vibration and noise by spreading in an engine. Therefore, it can be said that reducing the vibration of combustion, which increases as the compression ratio increases, is same technology with improving thermal efficiency. Regarding the function of reducing combustion vibration, we are conducting model-based research on technology to reduce vibration by applying a granular damper to the piston. To reducing the vibration of combustion efficiently, we attempt to suppress the vibration directly with the piston, which is the source of the vibration. In this way, the damping effect is maximized within the minimized countermeasure range. The damping system is a piston equipped with an additively manufactured particle damper (AMPD), which has porous voids (lattice structure) that can be manufactured by methods such as Laser beam powder bed fusion (LPBF). For the installation of AMPD, we propose a structure that achieves the same or better effect even if other damping materials are reduced by performing an optimal design that enhances productivity. In this paper, we describe the design method of the vibration damping lattice piston and the construction of a prediction method using the discretized element method for vibration damping performance by AMPD. The designed pistons are manufactured by LPBF or casting. In addition, we consider the results which is measured the vibration and noise characteristics when we change the type of particles in AMPD.