Study on Ring Conformability under Bore Deformation

This study proposes a method to calculate the limit of piston ring conformability to deformed bore based on measured gas leakage flow rate through ring-bore gap and calculated gap area using a test device that allows the creation of arbitrary bore deformation. As a result, it was clarified that predicted conformability can be matched with measured value by modifying a constant value in the conformability equation for a single order bore deformation proposed by Dunaevsky and Tomanik et al. Furthermore, it has been confirmed experimentally that the conformability limit index ∑U for the complex bore deformation proposed by Tomanik is valid. Using ∑U, area of gap between piston ring and deformed bore under engine operating condition was calculated to derive the relationship between blow-by gas flow rate.