Magnetorheological Fluid Fan Drive for Trucks

TLDR: In this article, a magnetorheological fluid (MRF) fan drive prototype for automotive truck application is designed and tested for both performance and durability, and a dual concentric gap with drum rotor design is chosen to meet the required torque capacity, packaging and mass constraints.

Abstract: A magnetorheological fluid (MRF) fan drive prototype for automotive truck application is designed and tested for both performance and durability. A dual concentric gap with drum rotor design is chosen to meet the required torque capacity, packaging, and mass constraints. Finite element magnetostatic modeling is performed to size the electromagnetic circuit and achieve the desired flux density levels in the MR fluid gaps. The clutch is filled with a custom-formulated MR fluid. Performance testing shows excellent speed control and response. The required 40 N-m torque capacity is achieved along with low drag speed, which is a key design characteristic of the fan drive. The clutch successfully passed several 500 h durability tests in a test cell environment. Performance testing indicates that the MRF clutch maintains its required torque capacity with very little increase in drag speed over the duration of the tests indicating no fluid thickening issues. The total dissipated energy in these tests is about 3.8GJ. The total specific dissipated energy for these tests is more than seven times higher than the 10 7 J/cm 3 upper limit previously suggested in the literature.