Efficient Overrunning Alternator Pulley (OAP) Design and Development for Robust FEAD System, Reduction of Fuel Consumption and CO2 for Model Gasoline Engine

Complex FEAD system in modern powertrain is reality today due to demanding regulation, hybrid powertrain and increasing customer expectation. Gasoline engines are going to be preferred over diesel engines specially for passenger car application. These downsized engines lead to increase engine excitation and so to higher dynamics. Use of overrunning alternator pulley (OAP) is globally accepted as cost effective and technically proven product for FEAD system to make it robust by optimizing the system performance such as belt tension, hub load, slippage and vibrations to improve fuel consumption and to reduce engine emissions. OAP is a mechanical device with one-way clutch unit which eliminates the torsional vibrations coming from engine crankshaft and ensures only accelerating proportions of crankshaft forces are transferred to alternator which means reduction in force level of belt drive system.

This paper describes the advantage of usage of OAP to achieve reduction in fuel consumption and emissions, to make the FEAD system efficient over the rigid alternator pulley by eliminating the rotational irregularities coming from FEAD system. In this paper, various engine driving conditions have been simulated to assess FEAD system performance in terms of hub load, belt pre-tension, belt slippage and vibrations by comparing rigid pulley and overrunning alternator pulley, followed by engine validation, which shows effectiveness of OAP.