Electric induction machine

Patent metadata

Field	Value
Publication number	US-11888366-B2
Application number	US-202017134712-A
Country	US
Kind code	B2
Filing date	Dec 28, 2020
Priority date	Jun 29, 2018
Publication date	Jan 30, 2024
Grant date	Jan 30, 2024

Abstract

The disclosure relates to an electric induction machine in which a chamfer region is provided between each respective rotor groove and rotor bar at a position corresponding to a radially outer internal corner region of the rotor groove. Suitably, the chamfer region has a relative magnetic permeability less than that of the rotor frame, and an electrical resistivity higher than that of the rotor bar. Moreover, a minimum diameter of the chamfer region is suitably larger than a manufacturing-tolerances derived maximum clearance between the respective rotor groove and robot bar, if any.

First claim

The invention claimed is:

1. An electric induction machine, comprising:
a housing having an inner space;
a stator assembly arranged annularly within the inner space of the housing;
a shaft rotatably supported so as to concentrically extend through the stator assembly; and
a rotor assembly fixed to and surrounding the shaft within the inner space, the rotor assembly being disposed concentrically with and inside the stator assembly, wherein the rotor assembly further comprises:
a cylindrical rotor frame;
a plurality of axially extending longitudinal rotor grooves spaced circumferentially along the rotor frame, each rotor groove being rectangular in shape;
a plurality of longitudinal rotor bars accommodated within the rotor grooves, each rotor bar comprising a rectangular shape corresponding to the rectangular shape of a corresponding rotor groove except for a chamfer region;
a plurality of slits, each slit extending radially outward from a radial outer side of each respective rotor groove to an outer circumference of the rotor frame; and

the chamfer region formed in only each respective rotor bar as a gap between each respective rotor groove and rotor bar pair at a position corresponding to a radially outer internal corner region of the rotor groove,
wherein the gap of the chamfer region does not extend in the tangential direction of the rotor frame beyond a tangentially closest side of the slit.

2. The electric induction machine according to claim 1 , wherein the chamfer region has a relative magnetic permeability less than that of the rotor frame, and an electrical resistivity higher than that of the rotor bar.

3. The electric induction machine according to claim 2 , wherein a minimum diameter of the chamfer region is larger than a manufacturing-tolerances derived maximum clearance between the respective rotor groove and rotor bar, if any.

4. The electric induction machine according to claim 3 , wherein a cross-sectional profile of the chamfer region is concave on a side abutting the rotor bar, as seen along a longitudinal direction of said rotor bar.

5. The electric induction machine according to claim 1 , wherein a cross-sectional profile of the chamfer region is linear on a side abutting the rotor bar, as seen along a longitudinal direction of said rotor bar.

6. The electric induction machine according to claim 1 , wherein each respective rotor groove and rotor bar pair comprises two chamfer portions symmetrical with respect to each other along a radial symmetry axis.

7. The electric induction machine according to claim 1 , wherein each respective rotor groove and rotor bar pair comprises two chamfer portions unsymmetrical with respect to each other along a radial symmetry axis.

8. The electric induction machine according to claim 1 , wherein the chamfer region has a height in the radial direction of the rotor frame fat and a width in the tangential direction of the rotor frame, wherein the height of the chamfer is ¼-2 of the width of the chamfer region.

9. The electric induction machine according to claim 8 , wherein the rotor bar has a height in the radial direction of the rotor frame, and wherein the height of the chamfer region is 1-10% that of the rotor bar.

10. The electric induction machine according to claim 9 , wherein the rotor bar has a width in the tangential direction of the rotor frame, and wherein the width of the chamfer region is 10-90% that of the rotor bar.

11. The electric induction machine according to claim 1 , wherein the electric induction machine is an electric motor having a pre-determined rotation direction,
wherein each respective rotor groove and rotor bar pair have a single chamfer region at position corresponding to a radially outer internal corner region on a trailing side of the rotor groove with respect to the pre-determined rotation direction.

12. The electric induction machine according to claim 1 , wherein the electric induction machine is an electric generator having a pre-determined rotation direction,
wherein each respective rotor groove and rotor bar pair have a single chamfer region at position corresponding to a radially outer internal corner region on a leading side of the rotor groove with respect to the pre-determined rotation direction.

13. The electric induction machine according to claim 1 , wherein a minimum diameter of the chamfer region is larger than a manufacturing-tolerances derived maximum clearance between the respective rotor groove and rotor bar, if any.

14. The electric induction machine according to claim 1 , wherein a cross-sectional profile of the chamfer region is concave on a side abutting the rotor bar, as seen along a longitudinal direction of said rotor bar.

15. The electric induction machine according to claim 8 , wherein the rotor bar has a width in the tangential direction of the rotor frame, and wherein the width of the chamfer region is 10-90% that of the rotor bar.

16. The electric induction machine according claim 5 , wherein each respective rotor groove and rotor bar pair comprises two chamfer portions symmetrical with respect to each other along a radial symmetry axis.

17. The electric induction machine according to claim 2 , wherein the electric induction machine is an electric motor having a pre-determined rotation direction,
wherein each respective rotor groove and rotor bar pair have a single chamfer region at position corresponding to a radially outer internal corner region on a trailing side of the rotor groove with respect to the pre-determined rotation direction.

18. The electric induction machine according to claim 2 , wherein the electric induction machine is an electric generator having a pre-determined rotation direction,
wherein each respective rotor groove and rotor bar pair have a single chamfer region at position corresponding to a radially outer internal corner region on a leading side of the rotor groove with respect to the pre-determined rotation direction.

19. The electric induction machine according to claim 2 , wherein a cross-sectional profile of the chamfer region is concave on a side abutting the rotor bar, as seen along a longitudinal direction of said rotor bar.

Assignees

• Abb Schweiz Ag

Inventors

• Heikel Mikael
• Szucs-Bartfai Mark
• Szucs Aron
• Szucs-Bartfai Blanka
• Kovacs Zsolt
• Westerlund Jan

Classifications

• H02K17/20 Primary

  having deep-bar rotors · CPC title

• H02K17/42

  Asynchronous induction generators (H02K17/02 takes precedence) · CPC title

• H02K2213/03

  Machines characterised by numerical values, ranges, mathematical expressions or similar information · CPC title