Browse Publications Technical Papers 2018-28-0102


ENHANCEMENT OF STARTER BRUSH LIFE FOR MICRO HYBRID (START/STOP) APPLICATIONS In Micro hybrid, start-stop system automatically stop and start the engine to reduce the idling time of engine spend in traffic jams and signals, thereby reducing fuel consumption and emissions. Starter motors used in Micro hybrid (Start/Stop) application has 5~10 times more life cycles than compare to conventional starter because of need to starter in every idling time of engine. There are multiple components in starter motor have sliding contact (mechanical/electrical), rolling contact will inflict the life cycles of starter motor. Brush is one of the major sliding contact elements to inflict the life cycle of starter, brushes are commonly used to conduct current between the stationary and moving part of starter. Brushes are exposed both mechanical and electrical loading conditions. Brush wear is affected by the association of Mechanical wear and electrical wear. The mechanical wear inflicted by various factor including Material composition, material properties, Sliding speed, sliding distance, Contact force (Spring force) while the electrical wear inflicted by various factor including under/over commutation, Current density, contact resistance and also affected by environmental factors like humidity, temperature. The main objective of this paper is to optimize the brush life of Metal(Copper) graphite brush for Micro hybrid (start/stop) applications starter motor by means of reducing brush wear through optimize the brush wear influential factors. Dynamically measure the brush wear rate in various condition by changing brush material, sliding speed, contact force, current density, temperature and humidity are in with and with-out applying current. And also continuously measure the changes in brush temperature, coefficient of friction, voltage drop and contact resistance. From this data we calculate the percentage of each contributing factors over brush life and create the mathematical model to estimate the brush life in design stage itself. This will help to avoid the wastage of testing time over wrongly selected brush grade and also able to optimize the brush life for a particular application.


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