Slotless stators and methods for manufacturing such stators

A tool for manufacturing a stator for use in a slotless electric motor, wherein the tool comprises:

• a tool body with a central bore and a multitude of hook pins;
• wherein said hook pins can be moved between a first, operative configuration and a second, retracted configuration;
• wherein in said operative configuration of the hook pins, the inner ends of the hook pins protrude into the central bore of the tool body;
• and
• wherein in said retracted configuration of the hook pins, the inner ends of the hook pins are retracted, such that the distance of the inner ends of the hook pins from the longitudinal axis is larger than in the operative configuration.

A method for manufacturing a stator for use in a slotless electric motor, comprising the steps:

• providing a stator lamination stack of the stator, the stator lamination stack having the form of a hollow cylinder with an outer radius (Rsls) and a bore with an inner radius (rsls);
• providing a multitude of hook pins on one or both longitudinal ends of said stator lamination stack in a first configuration, the multitude of hook pins protruding toward a longitudinal axis of the stator lamination stack, and the inner ends of said hook pins having a distance from said longitudinal axis that is smaller than the outer radius (Rsls) of the stator lamination;
• winding three or more wire coils across the bore of the stator lamination stack, the individual wires inside the bore being oriented essentially parallel to the longitudinal axis, and the individual wires on the longitudinal ends of the coils outside the stator lamination stack being placed on the multitude of hook pins;
• moving the multitude of hook pins in a second configuration, in which said multitude of hook pins no longer support the individual wires;
• and
• compressing the wires on the longitudinal ends of the coils outside the stator lamination stack in a toroidally shaped winding head with an inner radius (rwh) that is essentially equal to the inner radius (rws) of the coils inside the stator lamination stack.