JOINT AND JOINTING METHOD IN A PERMANENT MAGNET SYNCHRONOUS MACHINE

• US 20140028144A1
• Filed: 01/25/2012
• Published: 01/30/2014
• Est. Priority Date: 01/26/2011
• Status: Active Grant

• Current Assignee: Danfoss Editron Oy (Danfoss A/S)
• Original Assignee: Axco-Motors Oy (Danfoss A/S)
• Inventors: Parviainen, Asko, Piispanen, Ari
• Granted Patent: US 9,660,494 B2
• Time in Patent Office: Days
• US Class Current: 310/210
• CPC Class Codes: H02K 1/223 Rotor cores with windings and permanent magnets for additional excitation in synchronous motors or generators H02K21/042; in synchronous motors having additional short-circuited winding for starting as an asynchronous motor H02K21/46
• CPC Class Codes: H02K 15/0012 Manufacturing cage rotors
• CPC Class Codes: H02K 21/12 with stationary armatures and rotating magnets
• CPC Class Codes: H02K 3/16 for auxiliary purposes, e.g. damping or commutating

Abstract

The invention relates to a joint between a copper short-circuiting ring (1) and a copper bar (2) of the damper winding in a permanent magnet synchronous machine, wherein the end of the bar is jointed to a hole (9) disposed in the short-circuiting ring by welding them together at the mating surfaces. Further, the invention relates to a corresponding method. According to the invention the short-circuiting ring (1) includes a blocking structure for limiting the heat flux from being conducted further into the short-circuiting ring from the weld between the short-circuiting ring and the bar.

Claims

1. A joint between a copper short-circuiting ring and a copper bar of the damper winding in a permanent magnet synchronous machine, wherein the end of the bar is jointed to a hole disposed in the short-circuiting ring by welding them together at the mating surfaces, wherein the short-circuiting ring includes a blocking structure for limiting the heat flux from being conducted further into the short-circuiting ring from the weld between the short-circuiting ring and the bar.

2. The joint according to claim 1, wherein the blocking structure includes a sleeve-type framing around the hole on the surface of the short-circuiting ring, whereby the welded joint between the short-circuiting ring and the bar is formed between the sleeve-type framing of the hole of the short-circuiting ring and the bar.

3. The joint according to claim 1, wherein the blocking structure is formed by a ring-type groove made around the hole to a distance therefrom.

4. The joint according to claim 1, wherein the blocking structure is formed by a ring-type sheath extending upward from the surface of the shirt-circuiting ring in the direction of the hole.

5. The joint according to claim 1, wherein the end of the bar includes a central recess, which constitutes a sleeve-type framing to the end of the bar.

6. A method for welding together a copper short-circuiting ring and a copper bar of the damper winding in a permanent magnet synchronous machine, wherein the end of the bar is jointed to a hole disposed in the short-circuiting ring by welding them together at the mating surfaces, wherein at least one of the pieces to be welded is shaped in the vicinity of the mating surfaces to be welded so that the free conduction of heat outside the weld in the pieces to be welded is limited.

7. The method according to claim 6, wherein the free conduction of heat to the bar is limited by providing the end of the bar with a central recess.

8. The method according to claim 6, wherein the free conduction of heat to the short-circuiting ring is limited by machining a groove around the hole disposed in the short-circuiting ring, to a distance from the hole.

9. The method according to claim 6, wherein the magnetic circuit of the permanent magnet synchronous machine is short-circuited before welding for the area to be welded to minimize the leakage flux preventing the welding.

10. The method according to claim 9, wherein the short-circuit is made by a massive iron mass extending from under the short-circuiting ring of the rotor, from around the bars and from contact thereto, along the outer casing of the rotor in the vicinity of the area to be welded.

11. The method according the claim 10, wherein the iron mass is used to cool the permanent magnet poles of the rotor at the bars to be welded.

12. The method according to claim 11, wherein the iron mass is cooled by a cooling circulation surrounding it and/or passing through it.