The radial deformation of MRE rings (magnetorheological elastomer) in a radially oriented magnetic field can be continuously controlled by the current of the magnetic coil, i. e. the radial gap between MRE ring and magnetic yoke can be closed continuously and opened again. This creates the characteristic of a proportional valve. A difference to conventional proportional valves is the radial instead of a linear closing movement, which makes the valve compact.
The characteristics of the MRE valve can even be adjusted within a wide range due to the properties of the MRE rings used. A harder MRE ring needs a stronger magnetic field to close the valve. But this valve can withstand higher pressures in the closed state.