PROPERTIES AND DESIGN OF VALVES FOR MAGNETORHEOLOGICAL FLUIDS

摘要

The advantages of hydraulics, i. e. high energy to volume ratio as well as high stroke values, can be combined with the advantages of magnetorheological fluids (MRF), i. e. rapid reaction and straightforward valves without any moving parts, to create fast and compact actuators. This paper presents an approach for the design and dimensioning of MRF valves considering the MRF flow channel and flux path dimensions, coil parameters and permanent magnets and to examine their influence on static and dynamic properties of MRF valves. An iteration algorithm is used to calculate and simulate the magnetic properties of the valves. The calculation scheme considers eddy currents in the flux linkage as well as the excitation of the magnetic system by current sources and permanent magnets. Mesh current analysis is used to calculate the magnetic flux within polarized magnets. A solution for considering non-linear magnetic material properties of different soft magnetic materials, permanent magnets and of MRFs has been developed to assist the selection of the material used for the valves. By building up a simulation model using the iterative algorithm the dynamic behaviour of MRF valves can be analysed. The model can be used to simulate and optimise complete hydraulic drives and their controller.