On/Off solenoid with sensorless position detection

As is generally known, pressure-resistant solenoids for valves are used in hydraulics and pneumatics. These solenoids, for example, consist of a so-called pole tube with an integrated armature and a separate solenoid coil. Suitable displacement measuring systems are used in order to measure the armature´s as well as valve spool´s position constnatly; these ar directly mounted to the solenoid. Exeamples here are Hall Effect sensors or LVDT transducers. In case of lesser requirements, it is also possible to measure the valve spool´s position directly and in simplified manner. Here, partially standard proximity sensors are employed, which use the valve spool directly as measuring object. In these cases, however, only discrete position measurement is possible. A constant displacement measurement is not necessary. By means of the sensorless position-control developed by MSM, the armature´s position can be executed directly by analyzing the solenoid coil, partly replacing the usual sensors, under adapted basic conditions.