Fracture analysis on flywheel bolt of ISG motor for hybrid bus

摘要

Using tool such as torque wrenches, air guns, speed sensors and bolt fastening analyzer, the causes of flywheel bolt fracture of ISG motor was analyzed, respectively from the fixed structure of hybrid bus, tightening performance of bolt and clutches shock characteristics. The results show that lack of tightening torque and excessive torque occurred from clutches shock were the major causes of over-fatigue about flywheel bolt for hybrid bus. The solutions were proposed to prevent the connecting fracture of flywheel bolt, included using level 10.9 Hexagon bolt to increase the tensile strength, and using torque wrench to reset torque value, and insuring clutches engagement synchronously to reduce torque shocks.