Method for assembling a stator for an electric machine

• US 4,173,822 A
• Filed: 12/30/1977
• Issued: 11/13/1979
• Est. Priority Date: 07/10/1975
• Status: Expired due to Term

• Current Assignee: Interelectric AG (Karl-Walter Braun, PhD)
• Original Assignee: Interelectric AG (Karl-Walter Braun, PhD)
• Inventors: Fritschy, Hugo, Mayer, Jurgen, Futterer, Bodo
• Primary Examiner(s): Hall, Carl E.
• Application Number:
  US05/865,979
• Time in Patent Office: 683 Days
• Field of Search: 29/596, 29/598, 310/43, 310/42, 310/266, 264/262, 264/272
• US Class Current: 29/596
• CPC Class Codes: H02K 15/03 having permanent magnets
• CPC Class Codes: H02K 15/16 Centering rotors within the stator; Balancing rotors
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine

Abstract

A method for assembling a stator for an electric machine having a permanent magnet for generating a magnetic field in an air gap. Assembly of the stator is performed with the aid of a plunger, the cross-section of which corresponds to the cross-section of the air gap. The permanent magnet is slid into the interior of the plunger, whereas the flux return ring is slid over the same. The so formed sub-assembly is put into a casting mold adapted to be filled with a plastics material, which in its cured or hardened state forms a casing intimately surrounding the outer surface of the flux return ring and forming a face plate, to which the permanent magnet adheres. When the plastics material has set, the casting mold is opened and the plunger is retracted from the sub-assembly, resulting in a close toleranced cylindrical air gap space. After insertion of a bell-shaped rotor, a brush cover is assembled opposite the face plate. The flux return ring may be longitudinally slotted and biased so as to more intimately contact the calibrated tube during assembly in order to reduce the air gap tolerances. Instead of a plastics casing, a cup-shaped casing of a malleable or deformable material may be used.

Claims

1. A method of assembling a stator for an electric machine of the type having a bell-shaped rotor, a permanent magnet, a face plate holding said permanent magnet, a flux return ring abutting said face plate with one of its end faces and concentrically surrounding said permanent magnet, a casing intimately surrounding the outer surface of said flux return ring, comprising the steps of:

(a) sliding the permanent magnet into the interior of a support die, a plunger fitting into said die having an inner wall defining a cylindrical portion, the diameter of which corresponds to the inner diameter of the air gap space of said machine;

(b) sliding a flux return ring over the outer wall of said plunger;

(c) placing over the assembly, so obtained, a casting mold having a cavity conforming to the configuration of said stator;

(d) closing said mold and injecting plastic material thereinto;

(e) allowing the plastic material to harden;

(f) retracting the plunger from said die; and

(g) disassembling said die mold and removing the stator therefrom.

2. A method as claimed in claim 1, wherein a sealing ring is placed onto the front edges of the face plate side of the permanent magnet and of the flux return part after placing the entire assembly into said casting mold and prior to closing same.

3. A method as claimed in claim 1, wherein the flux return ring is slotted longitudinally over its whole length and is biased radially inwardly prior to sliding it over said calibrated tube.

4. A method as claimed in claim 3, wherein at least one bearing is placed into said casting mold prior to closing same.