Induction motor

Abstract

To provide a technique capable of efficiently cooling a rotor bar.SOLUTION: An induction motor may also comprise: a shaft; a first cooling passage extending in an axial direction of the shaft inside of the shaft; a rotor core which is fixed to the shaft; a rotor slot which is provided in the vicinity of an outer peripheral surface of the rotor core; and a rotor bar which is inserted into the rotor slot. The induction motor may also comprise: a resin member which covers an outer peripheral surface of the rotor bar; a second cooling passage extending along the rotor bar inside of the resin member; and a communication path communicating the first cooling passage and the second cooling passage.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The technology disclosed in this specification relates to an induction motor. [Background technology]

[0002] An induction motor is disclosed in Patent Document 1. The induction motor in Patent Document 1 includes a shaft, a rotor core fixed to the shaft, rotor slots provided near the outer circumferential surface of the rotor core, and rotor bars inserted into the rotor slots. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-015845 Summary of the Invention [Problem to be solved by the invention]

[0004] In the induction motor of Patent Document 1, the rotor bars may generate heat when the induction motor is operated. This specification provides a technique for efficiently cooling the rotor bars. [Means for solving the problem]

[0005] In a first aspect of the present technology, an induction motor may include a shaft, a first cooling passage extending inside the shaft in the axial direction of the shaft, a rotor core fixed to the shaft, a rotor slot provided near an outer circumferential surface of the rotor core, and a rotor bar inserted into the rotor slot. The induction motor may also include a resin member covering an outer circumferential surface of the rotor bar, a second cooling passage extending inside the resin member along the rotor bar, and a communication passage connecting the first cooling passage and the second cooling passage.

[0006] According to this configuration, since the second cooling passage is disposed in the vicinity of the rotor bar, the rotor bar can be efficiently cooled. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view of an induction motor according to an embodiment. [Diagram 2] A portion of the cross-sectional view taken along line II-II of Figure 1. [Diagram 3] An enlarged view of part III of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 1, an induction motor 2 of the embodiment includes a rotor 10 and a stator 90. The induction motor 2 is mounted on, for example, an electric vehicle (for example, a hybrid vehicle or an electric vehicle). The induction motor 2 functions, for example, as a power source for the electric vehicle.

[0009] The rotor 10 is configured to be rotatable relative to the stator 90. The stator 90 is disposed around the rotor 10. The rotor 10 rotates when a three-phase alternating current flows through the stator 90. The rotor 10 includes, for example, a shaft 30, a rotor core 12, and a cage conductor 40.

[0010] The shaft 30 extends in the direction of the rotation axis of the rotor 10. The shaft 30 includes an outer member 32 and an inner member 34. The outer member 32 is made of, for example, metal, and is configured in a cylindrical shape with a bottom. An insertion space 36 into which the inner member 34 is inserted is provided inside the outer member 32.

[0011] A plurality of communication holes (a plurality of first communication holes 38 and a plurality of second communication holes 39) extending in the radial direction are provided in the side surface of the outer member 32. The plurality of communication holes 38, 39 penetrate the side surface of the outer member 32. The first communication hole 38 is provided in the axial tip portion of the outer member 32. The first communication hole 38 is provided on the tip side of the rotor core 12 in the axial direction of the outer member 32. The second communication hole 39 is provided on the base end side of the first communication hole 38 in the axial direction of the outer member 32. The second communication hole 39 is provided on the base end side of the rotor core 12 in the axial direction of the outer member 32. The first communication hole 38 communicates with a first communication passage 52 described later, and the second communication hole 39 communicates with a second communication passage 56 described later.

[0012] The inner member 34 is made of, for example, metal, and is configured in a bottomless tubular shape. An inner passage 304 is provided inside the inner member 34. The inner member 34 is inserted into an insertion space 36 inside the outer member 32. As a result, an outer passage 302 is provided between the outer member 32 and the inner member 34. The inner passage 304 and the outer passage 302 extend in the axial direction of the shaft 30, and communicate with each other at an end of the shaft 30 in the axial direction. In this configuration, the cooling liquid (e.g., water or oil) that has flowed through the inner passage 304 flows into the outer passage 302 at the end of the shaft 30 in the axial direction. The inner passage 304 and the outer passage 302 form a first cooling passage 3.

[0013] Rotor core 12 is formed, for example, by stacking a plurality of electromagnetic steel sheets of the same shape in the axial direction of shaft 30. A shaft hole 60 is provided in the radial center of rotor core 12. Shaft 30 is inserted into shaft hole 60 of rotor core 12. With shaft 30 inserted into shaft hole 60, shaft 30 and rotor core 12 are fixed to each other by, for example, shrink fitting.

[0014] Furthermore, the rotor core 12 has rotor slots 14 into which rotor bars 16, described later, are inserted. A plurality of rotor slots 14 are provided in the rotor core 12. Each rotor slot 14 is provided near the outer circumferential surface of the rotor core 12. The plurality of rotor slots 14 are arranged at intervals in the circumferential direction of the rotor core 12. Each rotor slot 14 extends in the axial direction of the rotor core 12 (the axial direction of the shaft 30). The rotor slots 14 penetrate the rotor core 12 in the axial direction.

[0015] As shown in Figures 2 and 3, the rotor slot 14 has a shape in which, for example, the outer peripheral edge of the rotor core 12 is cut out in the radial direction of the rotor core 12. Note that Figure 2 shows a portion of the II-II cross section of Figure 1. The rotor slot 14 of this embodiment has an opening 142 and an insertion portion 144. The opening 142 of the rotor slot 14 opens on the outer peripheral surface of the rotor core 12. The insertion portion 144 is provided radially inward of the opening 142 of the rotor core 12. Note that the shape of the rotor slot 14 is not particularly limited.

[0016] A cage conductor 40 (see FIG. 1) of the induction motor 2 includes a plurality of rotor bars 16 and a pair of end rings 18 that connect the plurality of rotor bars 16. Both axial ends of the rotor bars 16 are fixed to the end rings 18. The end rings 18 extend in the circumferential direction of the rotor 10. The rotor bars 16 and the end rings 18 are made of a metal containing, for example, copper.

[0017] The multiple rotor bars 16 are arranged at intervals in the circumferential direction of the rotor 10. Each rotor bar 16 extends along the axial direction of the shaft 30. In a modified example, each rotor bar 16 may extend in a direction inclined with respect to the axial direction of the shaft 30. Each rotor bar 16 is inserted into an insertion portion 144 of each rotor slot 14 of the rotor core 12 (see Figures 2 and 3). A gap exists between the outer circumferential surface of the rotor bar 16 and the inner circumferential surface of the insertion portion 144.

[0018] The rotor slots 14 of the rotor core 12 are filled with a resin member 20 that seals the rotor bars 16. The resin member 20 is filled between the rotor core 12 and the rotor bars 16. The resin member 20 is filled into the openings 142 and the insertion portions 144 of the rotor slots 14. The resin member 20 covers the outer peripheral surfaces of the rotor bars 16.

[0019] The resin member 20 filling the rotor slots 14 is provided with a second cooling passage 22. The second cooling passage 22 is provided in each rotor slot 14. Thus, the induction motor 2 is provided with a plurality of second cooling passages 22. The second cooling passage 22 is provided in the resin member 20 filling the openings 142 of the rotor slots 14. The second cooling passage 22 is provided radially outward of the rotor core 12 relative to the rotor bars 16. The second cooling passage 22 is provided near the outer circumferential surface of the rotor core 12. The second cooling passage 22 is provided near the outer circumferential surface of the rotor bars 16. The second cooling passage 22 extends along the rotor bars 16 inside the resin member 20. For example, the second cooling passage 22 extends in the axial direction of the rotor core 12 along the rotor slots 14.

[0020] As shown in Fig. 1, the induction motor 2 of the embodiment further includes a plurality of passage members (a plurality of first passage members 50 and a plurality of second passage members 54). One end of each of the passage members 50, 54 is fixed to the outer circumferential surface of the outer member 32 of the shaft 30. The plurality of passage members 50, 54 extend radially from the outer circumferential surface of the outer member 32 in the radial direction of the rotor core 12. Each of the passage members 50, 54 extends from the outer circumferential surface of the outer member 32 to the vicinity of the outer circumferential surface of the rotor core 12. The other end of each of the passage members 50, 54 is fixed to an end face of the resin member 20 in the axial direction.

[0021] Each of the passage members 50, 54 is made of, for example, metal and is configured in a cylindrical shape. Among the plurality of passage members 50, 54, a first communication passage 52 is provided inside the first passage member 50. A second communication passage 56 is provided inside the second passage member 54. One end of the first communication passage 52 communicates with the first communication hole 38 provided in the outer member 32 of the shaft 30. One end of the first communication passage 52 communicates with the first cooling passage 3 via the first communication hole 38. The other end of the first communication passage 52 communicates with the second cooling passage 22 provided in the resin member 20. The first communication passage 52 communicates with the first cooling passage 3 and the second cooling passage 22.

[0022] Similarly, one end of the second communication passage 56 communicates with the second communication hole 39 provided in the outer member 32 of the shaft 30. One end of the second communication passage 56 communicates with the first cooling passage 3 via the second communication hole 39. The other end of the second communication passage 56 communicates with the second cooling passage 22 provided in the resin member 20. The second communication passage 56 communicates between the first cooling passage 3 and the second cooling passage 22.

[0023] In the induction motor 2 having the above configuration, for example, a coolant is supplied from a coolant supply device (not shown) to the inner passage 304 of the first cooling passage 3 of the shaft 30. The coolant that has flowed through the inner passage 304 flows into the outer passage 302 of the first cooling passage 3 at the axial end of the shaft 30. A part of the coolant that has flowed through the inner passage 304 flows through the first communication passage 52 and into the second cooling passage 22. The coolant flows through the second cooling passage 22, thereby cooling the rotor bar 16 arranged along the second cooling passage 22. The coolant that has flowed through the second cooling passage 22 then flows through the second communication passage 56 and again flows into the outer passage 302 of the first cooling passage 3. The coolant that has flowed through the outer passage 302 is returned to, for example, the coolant supply device.

[0024] According to the above-mentioned induction motor 2, even if the rotor bar 16 generates heat when the induction motor 2 is operating, the second cooling passage 22 is arranged in the vicinity of the rotor bar 16, so that the rotor bar 16 can be efficiently cooled. [Explanation of symbols]

[0025] 2: induction motor, 3: first cooling passage, 10: rotor, 12: rotor core, 14: rotor slot, 16: rotor bar, 18: end ring, 20: resin member, 22: second cooling passage, 30: shaft, 32: outer member, 34: inner member, 36: insertion space, 38: first communication hole, 39: second communication hole, 40: cage conductor, 50: first passage member, 52: first communication passage, 54: second passage member, 56: second communication passage, 60: shaft hole, 90: stator, 142: opening, 144: insertion portion, 302: outer passage, 304: inner passage

Claims

[Claim 1] A shaft, a first cooling passage extending in an axial direction of the shaft within the shaft; A rotor core fixed to the shaft; a rotor slot provided near an outer circumferential surface of the rotor core; A rotor bar inserted into the rotor slot, a resin member covering an outer circumferential surface of the rotor bar; a second cooling passage extending along the rotor bar inside the resin member; a communication passage that communicates the first cooling passage and the second cooling passage.

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