Designing for Six Sigma Using Transfer Functions - An Automatic Transmission Transfer Gear Design Case Study 2005-01-1208

This paper describes how DFSS tools provided the impetus in designing transfer gear for NVH performance and also discusses the design complexity and steps involved, tools used and the results obtained, within the DFSS framework. This paper describes gear noise reduction at source by reducing excitations at the transfer gear mesh with the given gear manufacturing variability. Gear Design for audible noise reduction is complex since the responses involved are continuous over a wide range of frequency and operating conditions. The objective here was to ensure that a future design meets the NVH targets cascaded to the component, in this case, transfer gears. The team used a Box Benkhen design to conduct hardware experimentation and subsequently to develop hundreds of transfer functions at different frequencies and operating conditions. These transfer functions (mathematical relationship between the response and the inputs) were utilized to optimize the design at critical frequencies and then predict the responses at all other frequencies. The trade offs involved are handled in a systematic manner using advanced optimization tools. The methodology used is extremely powerful in visually representing these trade offs as well as the predicted results vs. targets. Robustness Analysis of the recommended design at critical frequencies provides enhanced insight to the designer.