Designing a Tensioning Mechanism for a Belt-driven Integrated Starter-generator System

摘要

The B-ISG system is a transmission system characteristic to micro-hybrid automobiles. It is akin to traditional belt drives, differing in the fact that an electric motor, called an integrated starter-generator (ISG), replaces the original alternator, re-starts the engine from an idle stop and provides braking regeneration [2]. In the B-ISG setting the ISG is mounted on the belt drive. The ISG produces a speed of approximately 2000 to 2500rpm in order to spin the engine at approximately 750rpm and upwards to produce an instantaneous start in the start-stop process [3]. The high rotations per minute (rpm) produced by the ISG consistently places much higher tension requirements on the belt than when the crankshaft is driving the belt, and produces excessively slack spans coincidently in the belt. Increased slackness increases the amount of pretension needed. The traditional belt drive system's tensioner, a single-arm tensioner, does not suitably reduce the high belt tension nor provide enough tension in the slack belts spans that occur when the ISG re-starts the engine, which is when it drives the crankshaft pulley and accessory pulleys comprised within the belt transmission.