Study On Magneto-rheological Shock Absorber For Railway Vehicle Anti-yaw Vibration

When the railway vehicles run at a higher speed, the bogie may have a large amplitude horizontal swing movement in periodicity, that yaw vibration. Fierce yaw vibration increases the risk of derailment wheel, thereby threatening the safety of vehicle operation. Installing anti-yaw vibration absorbers can effectively inhibit the yaw vibration of the bogie, to ensure rail vehicles running safely. Most of anti-yaw vibration absorbers are cylinder hydraulic shock absorber at present. The parameters of hydraulic shock absorber are not changed, only in specific operating conditions to achieve optimal, so the hydraulic anti-yaw vibration absorber is lack of variable load; variable speed and adaptability to the unpredictable road conditions. As the rail vehicles in different driving condition of the damper characteristics have different requirements, adjustable damper is the objective of shock absorber technology development, Magneto-rheological (MR) shock absorber is a new high adjustable damping properties of intelligent devices.Aiming at the characteristics of traditional MR fluid shock absorber such as low utilization of magnetic field, high energy consumption, a kind of multistage radial flow model MR shock absorber was presented based on technical requirements of railway vehicle anti-yaw vibration absorber. The specific contents are as follows:(1) The technology of anti-yaw shock absorber and MR shock absorber is introduced, and the importance of the study on MR shock absorber for anti-yaw vibration is described, the existing problems that conventional MR shock absorber used in anti-yaw vibration are pointed out by reviewing related MR shock absorber research, a kind of multistage radial flow model MR shock absorber was presented, the purpose and content are proposed.(2) A test methodology for rheological behaviors of MR greases based on double rotational coaxial cylinder shear mode is presented to obtain high shear strain rate and magnetic flux density. The rheological properties of MR fluid were tested to provide material parameters for the design of MR shock absorber.(3) The high axial stiffness of the end of connecting structure; high damping coefficient and low unloading velocity of anti-yaw shock absorber were introduced; the technical requirements of railway vehicles for anti-yaw shock absorber were proposed. The multistage radial flow model MR shock absorber was presented, the working principle was described, the working cylinder design, the damping control valve design and circuit design of MR shock absorber were completed, the structural parameters of MR shock absorber were determined.(4) The radial flow model was described, The rheology equations and the computation formula of damping force of radial flow model are derived from hydrodynamics theory, based on Newton fluid model or generalized Bingham fluid model according to Navier-Stokes fluid dynamics equations. The magnetic field of damping control valve was analyzed, the relationship between shear yield stress and excitation current of MR fluid was obtained, calculated the damping force, gave out the radial velocity distribution of different location and radial velocity distribution of different current.(5) In order to evaluate the control features of MR shock absorber; the force-displacement; force-velocity and durability characteristics of the MR shock absorber were tested in the J95-I type oil pressure absorber test bed, comparing theoretical damping force and experimental damping force, analysis the main reasons for the errors.Finally, the paper is summarized; the special features and the problems that MR technology in railway vehicle applications require further research are outlined .