Impact on FEAD Dynamic Performance of Mild Hybrid Engine with Increase in Engine Torque

<div class="section abstract"><div class="htmlview paragraph">Front End Accessory Drive (FEAD) systems are used in automobiles to transfer power from the engine-to-engine accessory components such as the alternator, water pump, etc. using a Belt and Tensioner. The emergence of Mild hybrid technologies has led to the replacement of alternator with Belt-driven Integrated Starter-generator (B-ISG). In conventional configuration of FEAD, the power transfer is in single direction but in mild hybrid engine power transfer is bidirectional: tight and slack side of the Belt changes as per Torque assist or Regeneration mode. The presence of an integrated starter-generator (ISG) in a belt transmission places excessive strain on the FEAD System and necessitates checking the dynamic performance of FEAD System thoroughly.</div><div class="htmlview paragraph">Study of Increase in Engine Torque in existing Vehicle was done to understand its effect on various system. This vehicle is Mild Hybrid and consists of Belt-driven Integrated Starter generator system. Increase in Engine torque lead to increase in rotational fluctuation which directly impacts the FEAD System parameters such Belt slip, Belt Tension, etc. This paper presents the impact of increase in Engine Torque on dynamic performance of FEAD system through System performance test on Vehicle. System Performance test measures various parameters of Vehicle and FEAD System during different test patterns which are worst conditions for FEAD. These different Test patterns were identified based on ISG Modes (Assist, Generation and Regeneration) and various parameters such as Rotational fluctuation, ISG Torque, Battery SOC, etc. System performance Test result shows the Belt slip, Belt Tension and Tensioner behavior during ISG Modes (Assist, Generation & Regeneration). Measurement results were compared and analyzed, and it was judged that current FEAD design of the drive system meets the requirements of Engine with increased torque. Influence of increase in damping of Hydraulic Tensioner on FEAD performance parameter was also demonstrated. Approach followed for design verification in this paper have practical engineering significance for design and development of the FEAD System.</div></div>