Title: Optimization through NVH Analysis to Improve the Vehicle Acoustics and Quality of Transmission Shifter
text: Gear shift quality and feel determines the performance of the transmission. It is dependent on the synchronizer, shift system, gear shifter etc in a transmission. In this study the impact of the transmission shifter on the gear shift feel is detailed. More focus is paid towards the feel in terms of NVH characteristics. The rear wheel drive transmission shifter can be bifurcated into direct and indirect shift type. Indirect shifter are of two types, the rod type shifter and the cable shifter. The rod type shifter is analyzed in detail. All the shifters are connected to the gear shift top lever which is the customer interface for gear shifting. The design of the top lever is critical in getting the optimal feel of shifting and the mounting of the shifter is critical to improve its NVH characteristics. Different design iteration of the top lever are studied to illustrate the impact of the weight and stiffness on the vibration. CORRELATION OF A SEMI REMOTE SHIFTER MOUNTING ON VEHICLE ACOUSTICS AND VIBRATION is also established. The shifter dynamics are simulated and its NVH characteristics were studied for 4 cylinder engine and 3 cylinder engine. The shifter strength is analyzed with CAE on hyper mesh. The mechanical links involved and the iterations done to improve the shift quality as well the vibration levels of the hand ball are described. The biasing and shifting force and the travel of the knob in each gear are optimized by verifying through GSQA. Various rear wheel drive transmission have been used as an example to illustrate the shifter dynamics and efficiency. In a three cylinder engine the optimization of the semi remote shifter for the vibration and noise is critical. The solution can be common with a 4-cylinder engine if the arrangement is similar. The extent of benefit would be less on the 4-cylinder than with the 3-cylinder engine as it is more balanced. This study deals primarily with the mounting scheme of the semi remote shifter and its impact on the vehicle NVH. As the 3-cylinder engine configuration has the maximum drive train vibration, it enables a better understanding of the impact of the semi remote shifter mounting scheme on the vehicle. The analysis would help in the selection of the optimum semi remote shifter configuration and material with design adaptation suited to the engine configuration providing better NVH result on the vehicle.