The new Toyota Stop & Start system

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The new Toyota Stop & Start system

Asada, Toshiaki / Sakai, Kazuhito

Toyota, as first in the world, introduced an idle stop system, which used a pinion shift starter, in 1981. Based on mass-produced experience of idle stop systems, now Toyota has developed the world's first idle stop system, which uses a permanently engaged gear mechanism. It realizes excellent NV and quick response during engine stop and restart phase, and also responds immediately to the driver's 'Change of Mind' (i.e. engine restarting request before the engine is completely stopped). The system, called 'TOYOTA Stop & Start system', is used with a new petrol engine, and will be further expanded to other petrol engines and vehicles in the future. The system concept was realized through comparison of various engine starting methods, which finally resulted in the selection of a permanently engaged gear mechanism as best system for stop & start functionalities. Analysis of issues such as mechanical component stress and specific usage conditions was done using Multibody Dynamics simulation, evaluation with real vehicles, component unit tests and field tests. Detailed information about the stress and usage conditions was accumulated through these tests. Thereafter the Stop & Start system was designed appropriately and full reliability of the engine starting process was realized. This system, which is a combination of a permanently engaged gear mechanism and a refined electric power-control line, improved NV and response during engine stop and restart phase and also realized immediate response to the driver's 'Change of Mind'.