Crankshaft Positioning Utilizing Compression Force and Fast Starting with Combustion Assist for Indirect Injection Engine 2005-01-1166

Toyota has been continuing to study economy and general-purpose starting technologies for smaller displacement engines, since market introduction of the 42-14V MHV in 2001. This study shows one of the strategies for nearly silent and fast starting for economy size cars, which have smaller displacement engines by utilizing a small MG (motor generator) at 12 Volts.

The most significant issue for realizing advanced starting features (silent, fast and smooth) is the cost. Power electric components, especially, have a large cost disadvantage, which is generally proposed to the controlling power. So efforts were made to reduce the electrical power requirements. Also methods for minimizing additional components and utilizing conventionally existing components (e.g. sensors) are discussed in this paper.

Another characteristic is that smaller displacement engines (e.g. I4, I3) have larger cranking torque difference characteristics than larger engines (e.g. I6, I8).

Hence, this paper focuses on the cranking torque mechanisms analysis of cranking compression force. It shows crankshaft positioning control, utilizing compression force and inertia energy to reduce electrical restarting cranking power. Moreover the crankshaft positioning enables the conventional indirect injection engine to fuel one cylinder during the stopping process and realize combustion assisted restarting. A strategy employs balancing and optimizing mechanical compression and electric energy was developed. It realizes silent (10 dB improved) and fast (66% improved) novel starting, and saves electric cranking energy (50% reduced) compared to a conventional engine system. Furthermore, in order to analyze cranking characteristics from many sides, engine cranking simulation models were simultaneously studied with mechanical-electrical simulation. The simulation models were validated with experimental results and are shown in the paper.