Aspects of Shift Quality With Emphasis on Powertrain Integration and Vehicle Sensitivity 2005-01-2303

A customer's perception of vehicle quality very closely parallels the noise vibration and harshness (NVH) characteristics of the vehicle. Consequently, automotive manufacturers are investing significant resources into optimizing the NVH performance of their vehicles. Automatic transmission shift quality is one of a number of attributes where NVH optimization is critical towards providing customers with a pleasant driving experience. This paper addresses various aspects of understanding, quantifying and optimizing a vehicle's shift quality characteristics.

Following an introductory treatment of automatic transmission planetary gear systems, the interaction between the engine/transmission system during shifts is summarized. Various shift quality metrics used to quantify a vehicle's response and its sensitivity to transient inputs are provided. Approaches to manage the engine torque output during the shifts are discussed. Examples from various case studies are used to show the influence of the interaction between engine/transmission as well as the vehicle's sensitivity on the overall perceived shift quality behavior of the vehicle. The examples considered show how refined powertrain controls and upfront vehicle sensitivity considerations can be used to achieve superior shift quality.