Optimization of Engine Mounting System for First Gear Launch Judder

Normal engine mounting system is designed to carry loads of powertrain in all driving conditions and also isolate the vibrations of powertrain. Softer mounts are good for vibration isolation but it is not recommended to have softer mounts because durability will be affected adversely. Optimum stiffness needs to be finalized which will have balance between durability and performance. In addition to durability many performance parameters needs to be checked during the time of development. This study includes the development of engine mounting system for elimination of drive away judder in first gear. Maximum peak torque value for the drive-away event is in the range of 80Nm - 120Nm. In the worst case, this peak torque can reach to maximum 170Nm depending on maneuver, engine rpm is around 1100-1200. Steering wheel, instrument panel and whole vehicle cabin will vibrate for few seconds and then vehicle will run smoothly. To eliminate this issue, various iterations were done in the mounting system and solution is proposed which has no launch judder in 1st gear. A 6-DOF rigid body model is also established to simulate launch judder. Powertrain mounting system design has been modified to achieve the reduction in above mentioned vibrations. The pros & cons of the suggested change in mounting system on the overall NVH performance is also discussed in this paper.