Study On The Performance Of Magnetorheological Transmission Device

Magnetorheological Fluid (MRF) is a new intelligent material which is composed of micron-size ferromagnetic particles, carrier fluid and trace additive. The rheological properties of MRF changes rapidly, continuously and reversible under the application of an external magnetic field. Magnetorheological Transmission Device(MRTD), with rapid response, continuous adjustable output characteristics, and broad application prospect, is a new power transmission device which is using MRF as the transmission medium. According to the existing problems in the study of MRF and MRTD, the following aspects are thoroughly researched in the dissertation.The performance of MRF is tested and analyzed. In order to explore the controllable rheological mechanism of MRF, the formation process and particle chain structure of MRF under the magnetic field are observed using the built microscopic observation platform. Shear properties of MRF were tested by MCR301 rheometer and dependence of shear stress on magnetic field strength, shear rate and volume ratio is analyzed. The experimental results demonstrate that shear stress of MRF increases with the volume ratio, and the shear rate has little effect on its shear stress.When MRF is not saturated, dependence of shear stress on magnetic field strength tends to be linear.A new type of MRTD is developed based on the rheological performance of MRF. The new MRTD is designed based on shear-extrusion mode of MRF which not only improved the working performance effectively, but also reduced the adverse effect of centrifugal force. With its magnetic field and the flow field disturbed by the rotating magnetic cylinder, the developed new MRTD can deliver large and stable torque. Based on the established MRTD mathematical model, the design of the magnetic circuit and structure is completed and a complete MRTD design method is summarized.The transmission characteristics of MRTD were tested with the used of built experiment platform which includes the no-load characteristic, the static-load characteristic, the dynamic response characteristic, the speed control characteristic and the constant torque characteristic. It can be concluded that, when the excitation current is 0-2A, the relationship between torque and excitation current is linear. The response of the MRTD is rapid and it is increased with the magnetic field intensity.The loading response time is longer than unloading one and the slip speed has little effect on the response time when excitation current is constant. When the torque is constant, the designed MRTD can realize limitless transmission by adjusting the excitation current. With the influence of Magnetic column structure, the transmission torque of MRTD added slightly with the increase of slip speed when magnetic field strength is constant. The study has a reference value on the application and population of MRTD technology.