Magnetorheological Fluid-Based Continuously Variable Transmission

A continuously variable transmission (CVT) is proposed that utilizes magnetorheological (MR) fluids. Using a typical MR fluid with a saturation yield stress of 70 kPa at 1600 Oe, it appears feasible to design a 60 hp CVT within the desired volumetricfootprint: 3-inch axial length and 10-inch diameter. Initially, the Phase I will investigate the tradeoffs between the various possible approaches for the MR fluid-based CVT, in order to select the most promising concept. The effort will then proceed todevelopment of an optimum design for the selected concept. The design effort will address issues such as production and shaping of the activating magnetic field, viscous losses in non-activated regions of the MR fluid, overall efficiency, stresses incritical elements, and sealing of the MR fluid. We will conclude the program with testing on a representative small-scale prototype that incorporates the critical features and addresses the risks of the proposed MR fluid CVT.A compact, efficientcontinuously variable transmission (CVT) with high rpm capability offers improved fuel economy, reduced vehicle weight, reduced engine torque/speed demands, and reduced vehicle emissions. Such a CVT will also benefit products and equipment where there isvariable-speed mechanical power transmission.