Development of CAE technology for the design optimization of piston pin circlip

This study focuses on the technology for establishing design criteria for the piston pin circlip (hereinafter referred to as "circlip"), which is a component that holds the engine piston pin. The circlip is assembled into the piston by compressing it to the size of the piston circlip groove. However, in high-revving engines, the inertia forces caused by engine rotation can cause the circlip to disengage from the groove, potentially leading to the piston pin falling out and damaging the engine. To prevent this, it is possible to compress the circlip more and increase the reactive force acting on the groove to prevent falling out. However, this countermeasure raises concerns about the deterioration of the assemblability of the circlip. Therefore, it is necessary to establish evaluation criteria that prevent the circlip from disengaging and deteriorationg the assemblability of the circlip. To enable appropriate design of the circlip during the engine specifications review phase, we developed the following two technologies. The first is the development of a surrogate model that predicts the amount of plastic deformation of the circlip due to compression during circlip assembly process and thermal loads during engine warm-up. This surrogate model was created using data obtained from actual measurements and CAE analysis, using a regression model. The second is the development of CAE technology that predicts the likelihood of the circlip disengaging, taking into account the amount of plastic deformation. These technologies aim to support the optimization of circlip design and contribute to improving the reliability of the engine.