Research On High Power Magnetorheological Fluid Stability Transmission Technology

Magnetorheological fluid(MR fluid),which is mainly composed of micro-sized soft magnetic particles,carrier liquid and stabilizers,is a kind of intelligent materials.MR fluid power transmission adopts this smart material as working medium.As a new power transmission form,MR fluid transmission has many advantages,such as a quick and reversible response,simple control and low energy consumption,as well as high anti-interference ability,etc.Therefore,it possesses a broad application prospect in the fields of soft start,soft brake,stepless speed control and overload protection for mechanical equipment.According to the existing problems in current studies of MR fluid transmission,this dissertation conducts an in-depth research from the following aspects.The composition of MR fluid is described,and the selection of component material is analyzed,the influence of surface additive types and contents,thixotropic agent types and contents,the carrier liquid types on the sedimentation stability and apprarent viscosity of MR fluid are researched detailly,and a variety of transmission MR fluids are prepared which have widely temperature range.The rheological effect evolution of MR fluid is studied from macro and micro aspects,a small power experimental platform for MR fluid transmission is designed and constructed,and the related factors affecting transmission stability of MR fluid are researched systemically and the influence rules of rotate speed,temperature,particle sedimentation and response time are obtained,providing the reference for the design of MR fluid power transmission device.The basic structure and heat dissipation mode of a high power MR fluid transmission device are determined,a new type of transmission disk with hollow and magnetic cylinders is proposed,and based on this structure,a novel high power MR fluid transmission device is developed,moreover,its magnetic circuit is also analyzed in detail by the method of finite element.Three basic working conditions of MR fluid power transmission device are summarized,and the distribution characteristics of velocity and pressure fields are obtained based on the computational fluid dynamics method,and the influence of rotate speed,inlet velocity,inlet position and diameter and quantity of magnetic cylinders on flow field are studied.The steady and transient temperature fields under two common working conditions are obtained respectively,and the maximum slip power of the device is also discussed.It shows that the device has excellent heat dissipation performance and can meet the needs of high power transmission.An experimental platform for high power MR fluid transmission is designed and established,and the transmission performances including no-load torque,magnetic torque,dynamic characteristic,time response characteristic,temperature characteristic,and the temperature rise characteristic are tested respectively,obtaining the influence rule of different speed and slip power,cooling water flow speed and inlet position on the temperature of MR fluid.The results verify the effectiveness of the heat dissipation structure for high power MR fluid transmission.Research results from this dissertation play an important guiding significance to the thorough study of MR fluid transmission technology and they could provide a technical support for the design and application of high-power MR fluid transmission device.