The Kinematics and Dynamics of Engine Start Systems

Interest in low-voltage hybrid systems has grown because of the potential for significant fuel economy gains at a relatively low cost. Start/stop technology in hybrid powertrains is an economical technical approach in this general area of powertrain refinement. A new engine start mechanism concept is presented herein. It can change its operating state between two modes, respectively, involving a geared or belted connection to the crankshaft. This novel starter device enables an ultrafast start as well as a 5–10% fuel economy improvement, depending on voltage and power levels implemented. We also present a detailed engine cranking model developed in AMESim that distinguishes between motoring and firing events to get an accurate representation of engine dynamic torque response during engine start/stop events.