Design and Analysis of a Novel Magnetorheological Fluid Dual Clutch for Electric Vehicle Transmission

A novel magnetorheological fluid dual clutch (MRFDC) for electric vehicle transmission is proposed in this article. The structure was based on the MR fluid clutch and traditional dual clutch equipped on internal combustion engine vehicle. Therefore the MRFDC combines the advantages of MR fluid clutch and dual clutch transmission (DCT) to achieve high control accuracy and fast response. The structure of MRFDC was designed by Unigraphics (UG) three-dimensional (3D) modeling software. Then, finite element analysis (FEA) for magnetic field was conducted by ANSYS under different applied currents from 0.1A to 1A with 0.1A space to obtain the relation between the applied current and magnetic field. In this article, Herschel-Bulkley model is used to predict the MR fluid behavior because of the high shear rate of MR fluid. Finally, output torque of MRFDC can be estimated by calculus with geometric dimensions of MRFDC structure and rheological properties of MR fluid dependent on the magnetic field generated by the applied current. Finally the relation between the applied current and output torque of the internal clutch and external clutch can be obtained, respectively. Simulation results show that the relation between the output torque and the applied current can be considered linear for internal clutch under 0-1.0A current excitation. While the applied current is below 0.3A, the relation for external clutch can also be considered as linear. Thus, it is easy to use linear control methods to achieve gear shift based on mathematical models of MRFDC by controlling the applied current through the coil of the dual clutch under the requirement of achieving the maximum driving torque.