Magnetic Rotary-Linear or Linear-Rotary Converter

In an earlier paper,1 a magnetic rotary-to-linear convertor was described. This device was an extension of the principle of the linear helical reluctance motor in which a rotating magnetic field was achieved by rotating mechanically a set of permanent magnets. The convertor described in this paper is based on a further extension of the helical motor in which the saliency of both stator and armature is obtained in a double-start screw thread having rectangular slots. This modification permits two-way action of the device in its ability to convert rotary to linear displacement or vice versa. It is shown that the new arrangement results in a force/displacement characteristic modified from that obtained previously, and with a significant increase in maximum force. Preliminary theoretical and experimental results from a prototype version of the new device are described.