In order to solve the problem that the magnetic field strength distribution in the working gaps is not uniform and the braking torque per 1 m3is small in magnetorheological (MR) transmission,a novel MR brake configuration featuring double layer gaps and several coils arranged along the circumferential direction were proposed.An exact closed form expression of the braking torque was derived,and the magnetic circuit modeling was established to estimate the magnetic field strength in the gaps.Then,BOBYQA method was used to optimize the structural sizes,and the magnetic field strength distribution was conducted.Simulation was compared with the calculation of magnetic circuit.The results showed that the magnetic circuit modeling can guide the structure design,and the torque per 1 m3generated by the designed MR brake is about 2.3×104Nm/m3.The research results provides a theoretical reference for the design of double layer multi coil MR brake.
