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EP-4736297-A1 - FILLING A GROOVE WITH A THERMOPLAST COMPOUND IN AN ELECTRIC MACHINE

EP4736297A1EP 4736297 A1EP4736297 A1EP 4736297A1EP-4736297-A1

Abstract

A groove closure of a winding groove of an electric machine is to be efficiently produced. For this purpose, a viscous groove closure material is provided (S5, S6), the thermoplastic matrix of which is mixed with magnetizable particles. The viscous groove closure material is applied (S7) into the groove of the electric machine, and finally the viscous groove closure material is cooled (S8) in the groove, whereby the groove closure material is cured in the groove.

Inventors

  • Büttner, Klaus
  • KATZENBERGER, TOBIAS
  • KIRCHNER, FLORIAN
  • KIRCHNER, KLAUS
  • PLOCHMANN, Bastian
  • WARMUTH, MATTHIAS

Assignees

  • Innomotics GmbH

Dates

Publication Date
20260506
Application Date
20240610

Claims (14)

  1. 1. Method for filling a slot (1) of an electrical machine characterized by - providing (S5, S6) a viscous slot closure material in whose thermoplastic matrix magnetizable particles are mixed, - Applying (S7) the viscous slot sealing material into the slot (1) of the electrical machine, and - Cooling (S8) of the viscous slot sealing material in the groove, whereby the slot sealing material in the groove (1) hardens.
  2. 2. The method of claim 1, wherein the plastic matrix is a polyolefin.
  3. 3. The method according to claim 1, wherein the plastic matrix is a polyamide and in particular a polyamide-6.
  4. 4. Method according to one of the preceding claims, wherein 75 to 90 percent by weight of magnetizable particles, in particular iron powder, are mixed into the slot closure material (S3).
  5. 5. Method according to one of the preceding claims, wherein the application (S7) of the viscous slot sealing material into the slot of the electrical machine is carried out by extrusion or injection molding.
  6. 6. Method according to one of the preceding claims, wherein the application of the slot sealing material is carried out by a single-screw extruder or an application gun.
  7. 7. Method according to one of the preceding claims, wherein the slot closure material is heated to a maximum of 250°C, in particular to a maximum of 200°C, for application (S7).
  8. 8. Method according to one of the preceding claims, wherein the viscous slot sealing material is melted from a granulate (S6).
  9. 9. The method according to claim 8, wherein the melting (S6) of the slot closure material takes place immediately before the application (S7).
  10. 10. Method according to one of the preceding claims, wherein during the application (S7) of the viscous slot closure material into the slot (1) of the electrical machine, a viscous strand (10) of the slot closure material is applied to a wire bundle (6) in the slot (1).
  11. 11. The method according to claim 10, wherein the wire bundle is pressed in the direction of the groove base (3) of the groove (1) immediately before the application (S7) of the viscous strand (10).
  12. 12. The method according to claim 11, wherein after the application (S7) of the viscous strand (10), the wire bundle (6) relaxes in the groove and a part of the strand (10) is pressed behind a groove projection (5) of the groove (1) to form a positive connection.
  13. 13. Method according to one of the preceding claims, wherein the viscous strand (10) is pulled off flush with the surface after being introduced into the groove and/or is smoothed with a heating device.
  14. 14. Device for filling a groove (1) of an electrical machine characterized by - a melting device designed to melt (S2, S6) a slot closure material, in whose thermoplastic matrix magnetizable particles are mixed (S3), - an application device designed to apply (S7) the molten slot sealing material into the slot of the electrical machine and to allow the molten slot sealing material in the groove (1), whereby the slot sealing material in the groove (1) hardens.

Description

Description Groove filling using thermoplastic compound of an electrical machine The present invention relates to a method for filling a groove of an electrical machine. Furthermore, the present invention relates to a corresponding device for filling such a groove. Low-voltage motors are typically manufactured with a round wire winding, which is wound into coils in advance using a flyer/template winder and then drawn into the laminated core with the respective slots in a fully automated process. The critical point here is always the slot gap, which is defined by the two adjacent slot teeth. This is significantly smaller than the slot itself, which ideally means that the magnetic circuits close more effectively, but the entire copper winding has to be drawn through this cross-sectional taper. In order to generate ideal magnetic field properties in the laminated core, the slot gap would have to be chosen to be so narrow that the slot gap width is smaller than the diameter of a single wire in the winding. However, this would lead to major problems in terms of manufacturing, as typical winding drawing-in processes can no longer be used. The current sheet metal geometries are a kind of compromise that takes both requirements into account. The slot gap is approx. the clear width of two to four individual wires ( diameter ) , whereby the copper bundle is partially compressed to this width by a suitable lamella guide during insertion and the disadvantage with regard to the magnetic circuit dimensioning remains acceptable . Particularly in the case of larger machines (medium voltage or high voltage motors) with higher requirements, the existing slot gap is then closed using a magnetic slot closure. This is a magnetic tic iron particles of various designs, which are usually present in combination with a plastic as a "compound". This "compound" (filler particles = iron, matrix = plastic) is often prefabricated and used as slot wedges, which are mechanically inserted. This has the disadvantage that the slot lock can loosen and come off during operation of the machine due to vibrations and forces, thus blocking the rotor and thus leading to the failure of the machine. On the other hand, prefabricated slot gaps are not an economical solution for a product portfolio with a wide variety of variants, as is often the case in the area of low-voltage motors. Another application for medium and high voltage machines is the use of a still uncrosslinked, highly filled paste consisting of iron filler particles and chemical reactive resin (mixing ratio approx. 90 percent by weight iron filler, 10 percent by weight polymer matrix). The mass must be kneaded for several hours under active cooling to ensure homogenization of the particles in the matrix and then stored and transported in a cool place, as it is a one-component, reactive mass. The matrix component is, for example, an anhydrite-cured epoxy resin, which hardens when exposed to a higher temperature (150°C, several hours) to form a molding material that has sufficient mechanical strength and a glass transition temperature of over 140°C, thus meeting the requirements of medium voltage and high voltage machines for the insulation system and the peripherals. Due to the choice of matrix and iron filler composition as well as the high mechanical requirements for the final molding material and during application, additional additives such as talcum (as a lubricant) and polymer fibers (as reinforcement of the mass and thixotropy during processing) in the single-digit weight percentage range are necessary. The material is applied at room temperature either manually ("spackling") or by a (partially) automated bead application and subsequent pressing in using a special squeegee. Thermal hardening is then brought about by a hot air oven or by applying current to the windings. The object of the present invention is to propose an economical and low-energy possibility for slot filling, especially in low-voltage machines. According to the invention, this object is achieved by a method and a device according to the independent claims. Advantageous further developments of the invention emerge from the subclaims. The invention is based on the knowledge that low-voltage motors that have a high level of efficiency have only very low power losses, which manifest themselves in heating of the rotor and the stator, whereby a temperature of over 100 °C is almost impossible, particularly in the area of a possible slot closure. This allows a new perspective on the thermal stability of the insulation system and its periphery. In particular, the periphery (e.g. the cover slide) can be well below the thermal class F/H (155 °/180 °C, 20,000 h) otherwise required for the primary insulation system, without negatively affecting the service life or performance of the machine. Based on this development, the invention presents an alternative polymer solution for slot filling, which represents an economical and