Starting System for Stop/Start with Change of Mind
Further fuel consumption improvement of stop/start vehicles can be achieved by expanding the fuel cut period. In order to maintain vehicle response, ability to restart the engine during an engine stop event, known as change of mind (CoM), is necessary. Two current technologies to enable CoM are belt driven starter generator and permanently engagement starter. Both these technologies, however, require modification to additional vehicle components. The conventional pinion-shift-type starter has constant timing between pinion movement and motor rotation. If applied to CoM, the conventional starter risks making a loud noise or suffering serious mechanical damage during pinion engagement into the rotating ring gear of the engine and so is considered as unacceptable. Theses issues can be solved by using a new pinion-shift-type starter, which has independently controllable pinion movement and motor, and starter operation control, which can change the starter operation depending on engine speed. Furthermore, engine speed prediction based on engine rotational energy gives more accurate starter operation control which improves noise and restart response. The new pinion-shift-type starter and starter operation control with engine speed prediction has been fitted to vehicles and the performance compared to conventional starter systems. It is confirmed that engagement noise for CoM restart is equivalent to normal start engagement and that restart response is faster than current starting system with conventional starters. In this paper, details of the newly developed starter and starter control are described, together with performance of the new starting system.
KeywordsStop/start Fuel consumption Change of mind Starter Engine speed prediction
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