Low cost solutions to reduce cogging torque and acoustic noise of small brushed DC motors for automotive radiator Cooling Fan Modules

The paper focus is on the reduction of the acoustic noise emitted by radiator Cooling Fan Modules (CFMs) equipped with small brushed DC electrical motors. Initial measurements performed on standard production CFMs proved that the main part of the emitted noise is excited by specific cogging torque harmonics of the motor. Then, modifications in the motor production have been analyzed by means of electromagnetic Finite Element Method (FEM) simulations. The solutions held compatible with the cost-sensitive automotive component market and the actual automatic production lines have been implemented in special prototypes. The reported noise measurements results of CFMs equipped with these prototypes show the effectiveness of the proposed low-cost solutions for the cogging torque and emitted noise reduction.