Manufacture of a Production-Optimised Liner for Direct Winding Cooling of an Electric Machine

Abstract

This study deals with the development, production, and use of a cost-optimised solution for the media-tight separation of the rotor chamber from the stator chamber for use in direct-cooled electric machines. This results in a considerable cost optimisation regarding existing liner concepts. In addition, the use of a liner, manufactured in a transfer moulding process, offers advantages because the electromagnetics are not influenced, as is the case with metallic liners. The liner is manufactured with the help of a thermoset plastic in a single stage moulding process. Due to the integral design, a wide variety of functional assemblies, such as the seal, the end plates, and the sealing surfaces, are reproduced in one plastic component, which means that there are no separation points, and no finishing work is required. This increases the tightness and insulation strength and reduces the production effort. By making ideal use of features of the sheet metal package, wall thicknesses of the liner of less than 0.8 mm can be achieved through form-fit connections. Another special feature is the elimination of demoulding bevels through a patented tool concept, which enables a constant air gap. In the experimental investigations, the suitability of the moulded liner for use in an electric machine is demonstrated. This includes the required mould technology and the special features of process control when dealing with cross-linking plastics.