Development of Stop/Start Engine Combustion and Restart Control for Gasoline Direct Injection Automatic Transmission Application 2014-01-1747

Stop/Start technology for conventional automatic transmissions has recently received considerable attention in the automotive industry due to the potential fuel economy, and CO² emission reduction, benefit at minimal cost. Stop/Start was first developed for manual transmission applications in the EU and Japanese markets. When stop/start is applied to any automatic transmission powertrain the powertrain control challenge is to restart the engine in a manner that simultaneously minimizes the delay in transferring torque to the driven wheel(s) and provides a consistently smooth launch feel with low NVH. It has recently been shown that stop/start can be added to a gas engine powertrain with a conventional torque converter automatic transmission while achieving the desired launch characteristics with minimal change to the powertrain hardware and cost. This paper describes some of the powertrain control challenges that were addressed in the development of a stop/start system for conventional torque converter based automatic transmission applications. In particular the paper describes the stop/start restart engine and transmission characteristics that need to be addressed and provides a detailed description of the gasoline direct injection engine combustion and restart controls that were developed to support the goal of delivering consistently smooth and fast launch performance.