Squirrel-cage rotor and manufacturing method therefor

Abstract

Provided in the present application is a squirrel-cage rotor, comprising an iron core and a winding. The iron core defines rotor slots, recesses and channels, wherein the rotor slots extend along the entire axial length of the iron core; the recesses located at two axial ends of the iron core are recessed axially inward from an axial end face of the iron core; and the channels are formed at two axial ends of the iron core, and the recesses are in communication with the rotor slots via the channels. The winding is integrally formed by means of casting, and comprises two end rings, conductive bars, protrusions and connecting portions, wherein the end rings are arranged at two axial ends of the iron core; the conductive bars extend into the rotor slots from the end rings, and the protrusions extend into the recesses from the end rings; and the connecting portions are arranged in the channels, and the protrusions are connected to the conductive bars via the connecting portions. Further provided in the present application is a manufacturing method for the squirrel-cage rotor.

Description

Squirrel cage rotor and manufacturing method thereof TECHNICAL FIELD

[0001] The present application relates to the field of electric machines, and in particular to a squirrel cage rotor and manufacturing method thereof. BACKGROUND

[0002] Chinese patent application CN103999333A discloses an electric machine having end rings and support projections. A small portion of the end ring fills a space in the plane of the end lamination formed when the projection is bent out of the plane of the lamination. The engagement of the end ring portion with the end lamination helps to resist certain centrifugal forces acting on the end ring and to secure the end ring to the rotor core. However, the space in the plane of the end lamination is a blind hole. During the casting process, air cannot be effectively discharged from the blind hole, so that the small portion of the end ring has more air holes, thereby resulting in a lower strength structure strength of the small portion.

[0003] SUMMARY

[0004] The present application aims to overcome or at least alleviate the deficiencies of the prior art, and to provide an improved squirrel cage rotor and manufacturing method thereof.

[0005] The present application provides a squirrel cage rotor comprising: a core defining a rotor slot, a recess, and a passage, the rotor slot extending an entire axial length of the core, the recess being recessed from an axial end surface of the core to an axial inner side at both axial end portions of the core, the passage being formed at both axial end portions of the core, and the recess being communicated with the rotor slot via the passage; and a winding integrally formed by casting, the winding comprising two end rings, a bar, a projection, and a connecting portion, the end rings being provided at both axial ends of the core, the bar extending into the rotor slot from the end rings, the projection extending into the recess from the end rings, the connecting portion being provided in the passage, and the projection being connected with the bar via the connecting portion.

[0006] In an optional aspect, the rotor slot and the recess are arranged side by side in a circumferential direction of the squirrel cage rotor, and a thickness of the projection in the circumferential direction is 1 / 3 to 1 times a thickness of the bar in the circumferential direction.

[0007] In another optional aspect, the passage extends from a radially outer side of the rotor slot to a radially outer side of the recess, or the passage extends from a radially inner side of the rotor slot to a radially inner side of the recess.

[0008] In another optional aspect, an axial length of the passage is the same as an axial length of the recess, and the connecting portion extends to the axial inner side from the end ring.

[0009] In another optional solution, a plurality of the bars are evenly distributed in the circumferential direction of the squirrel-cage rotor, and each of the bars is connected to one of the protrusions via one of the connecting portions on each side of the squirrel-cage rotor in the axial direction.

[0010] In another optional solution, the core comprises a first lamination and a second lamination arranged in layers, the first lamination comprises a first through hole, the second lamination comprises a second through hole, the first through hole comprises a first portion and a second portion, the first portion coincides with the second through hole in the circumferential direction of the squirrel-cage rotor and defines the rotor slot together with the second through hole, and the second portion is staggered with the second through hole in the circumferential direction and defines the recess and the channel.

[0011] In another optional solution, the channel extends in the circumferential direction of the squirrel-cage rotor, the channel is arranged between the rotor slot and the recess, and the length of the protrusion in the radial direction of the squirrel-cage rotor is 80% to 120% of the length of the bar in the radial direction of the squirrel-cage rotor.

[0012] In another optional solution, the axial length of the protrusion and the connecting portion on each side of the squirrel-cage rotor in the axial direction is 1 / 10 to 1 / 30 of the axial length of the bar, and in the circumferential direction of the squirrel-cage rotor, the adjacent protrusion and the bar are separated by the teeth of the core.

[0013] The application also provides a manufacturing method of the above squirrel-cage rotor, the manufacturing method comprises: flowing a melt between the rotor slot and the recess via the channel.

[0014] In an optional solution, the casting is centrifugal casting or die casting, and the winding is made of aluminum alloy.

[0015] With the above technical solution, by arranging the channel, the melt can flow between the rotor slot and the recess via the channel. In the casting process, the air in the recess can be taken away with the melt, thereby reducing or even eliminating the pores in the protrusion. In this way, the protrusion can have a higher structural strength, so that the squirrel-cage rotor can have a higher upper limit of rotational speed. BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is a schematic view of a squirrel-cage rotor according to a first embodiment of the application.

[0017] FIG. 2 is another schematic view of the squirrel-cage rotor in FIG. 1.

[0018] FIG. 3 is a schematic view of a first lamination of the squirrel-cage rotor in FIG. 1.

[0019] FIG. 4 is a schematic view of a first through hole of the first lamination in FIG. 3.

[0020] Fig. 5 is a schematic view of a second lamination of the squirrel-cage rotor in Fig. 1.

[0021] Fig. 6 is a schematic view of an axial end portion of the core of the squirrel-cage rotor in Fig. 1.

[0022] Fig. 7 is a schematic view of a winding of the squirrel-cage rotor in Fig. 1.

[0023] Fig. 8 is a schematic view of an axial end portion of the winding in Fig. 7.

[0024] Fig. 9 is a schematic view of a first lamination of a squirrel-cage rotor according to a second embodiment of the present application. DETAILED DESCRIPTION

[0025] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood that the specific description is merely for the purpose of teaching one skilled in the art how to practice the present application, and is not intended to limit the scope of the present application.

[0026] (First Embodiment)

[0027] Figs. 1 and 2 are schematic views of a squirrel-cage rotor 30 according to a first embodiment of the present application.

[0028] The squirrel-cage rotor 30 can include a core 32 and a winding 34. The core 32 can be stacked by a plurality of first laminations 36 and a plurality of second laminations 38. The first laminations 36 can be arranged at both axial end portions of the core 32, and the second laminations 38 can be arranged at a middle portion of the core 32. The winding 34 can be made of an aluminum alloy and integrally formed by centrifugal casting. The core 32 can be a part of a casting mold, and the aluminum alloy in a molten state can be directly poured onto the core 32.

[0029] In other embodiments, the aluminum alloy can be replaced by a copper alloy or the like, and the centrifugal casting can be replaced by die casting or the like.

[0030] Fig. 3 is a schematic view of the first lamination 36.

[0031] The first lamination 36 can include a plurality of first through holes 40. The first through holes 40 can be provided at an outer circumferential portion of the first lamination 36, and the plurality of first through holes 40 can be arranged at regular intervals along a circumferential direction C.

[0032] Fig. 4 is a schematic view of the first through hole 40.

[0033] The first through hole 40 can include a first portion 42 and a second portion 44. The first through hole 40 can be formed substantially in a U-shape, a bottom of the U-shape can be radially outward of an opening of the U-shape. The first portion 42 can be formed as one radial portion of the U-shape, and the second portion 44 can be formed as a circumferential portion and another radial portion of the U-shape. In other words, the second portion 44 can be formed substantially in an L-shape, and the first portion 42 can be formed as a remaining portion of the first through hole 40.

[0034] FIG. 5 is a schematic view of the second lamination 38.

[0035] The second lamination 38 can include a plurality of second through holes 46. The second through holes 46 can be provided at an outer circumferential portion of the second lamination 38, and the plurality of second through holes 46 can be arranged uniformly at intervals along the circumferential direction C. The second through hole 46 can have substantially the same shape as the first portion 42.

[0036] FIG. 6 is a schematic view of an axial end portion of the core 32.

[0037] The core 32 can include a plurality of rotor slots 48, a plurality of recesses 50, and a plurality of passages 52. For adjacent first laminations 36, the first through hole 40 on one lamination and the first through hole 40 on another lamination can coincide with each other in the circumferential direction C (i.e., occupy the same circumferential position, overlap as viewed in the axial direction A) such that axial end portions of the rotor slots 48 can be defined by the plurality of first portions 42, the recesses 50 can be defined by the radial portions of the plurality of second portions 44, and the passages 52 can be defined by the circumferential portions of the plurality of second portions 44. For adjacent second laminations 38, the second through hole 46 on one lamination and the second through hole 46 on another lamination can coincide with each other in the circumferential direction C (i.e., occupy the same circumferential position, overlap as viewed in the axial direction A) such that middle portions of the rotor slots 48 can be defined by the plurality of second through holes 46. For adjacent first laminations 36 and second laminations 38, the first portion 42 and the second through hole 46 can coincide with each other in the circumferential direction C (i.e., occupy the same circumferential position, overlap as viewed in the axial direction A), and the second portion 44 and the second through hole 46 can be offset in the circumferential direction C such that the middle portions of the rotor slots 48 are connected between the two axial end portions of the rotor slots 48, and bottom surfaces of the recesses 50 and the passages 52 can be defined by axial end faces of the second laminations 38.

[0038] It is understood that, by stacking the first laminations 36 and the second laminations 38 in the above-described manner, each recess 50 can communicate with a rotor slot 48 via a passage 52. The rotor slots 48 can extend the entire axial length of the core 32. The recesses 50 and the passages 52 can be formed at axial ends of the core 32 and recessed from axial end faces of the core 32 toward the axial inside (axial middle position side). The rotor slots 48 and the recesses 50 can be arranged side by side in the circumferential direction C, and the passages 52 can extend from the radially outer side of the rotor slots 48 to the radially outer side of the recesses 50 in the circumferential direction C. The passages 52 can be formed with ports 54 on side walls of the recesses 50, and the ports 54 can cover the entire axial length of the recesses 50. The axial length of the passages 52 can be the same as the axial length of the recesses 50, so that the core 32 requires fewer types of laminations.

[0039] FIG. 7 is a schematic view of the winding 34.

[0040] The winding 34 can include a pair of end rings 56 and a plurality of bars 58. The two end rings 56 can be coaxially and oppositely arranged in the axial direction A, and the bars 58 can extend from one end ring 56 to the other end ring 56. The bars 58 can extend substantially in the axial direction A, or optionally, a middle portion of the bars 58 can form an angle with the axial direction A. Of course, in other embodiments, the entire bars 58 can be parallel to the axial direction A. Referring to FIGS. 1, 2, and 6, the two end rings 56 can be respectively provided at axial ends of the core 32, and each bar 58 can be fittedly provided in a rotor slot 48.

[0041] FIG. 8 is a schematic view of an axial end of the winding 34.

[0042] The winding 34 can further include a plurality of protrusions 60 and a plurality of connecting portions 62. The protrusions 60 and the connecting portions 62 can protrude from axial end faces of one end ring 56 toward the other end ring 56 in the axial direction A, and each protrusion 60 can be connected to a bar 58 via a connecting portion 62. Referring to FIGS. 1, 2, and 6, the protrusions 60 can be fittedly provided in the recesses 50, and the connecting portions 62 can be fittedly provided in the passages 52.

[0043] Preferably, the protrusions 60 and the bars 58 can be separated by teeth of the core 32. The thickness of the protrusions 60 in the circumferential direction C can be 1 / 3 to 1 times the thickness of the bars 58 in the circumferential direction C, and the axial length of the protrusions 60 and the axial length of the connecting portions 62 can each be 1 / 10 to 1 / 30 of the axial length of the bars 58. In this way, the protrusions 60 and the connecting portions 62 do not excessively encroach on the space of the core 32.

[0044] It is appreciated that the junction of the end ring 56 and the bar 58 is prone to stress concentration and thus forms a weak point. Accordingly, by extending the protrusion 60 into the recess 50, the protrusion 60 can share the load of the weak point so that the weak point is less likely to reach the yield limit, and thus the squirrel cage rotor 30 can have a higher upper limit of rotational speed. Further, the length of the protrusion 60 in the radial direction R can be 80% to 120% of the length of the bar 58 in the radial direction R, so that the protrusion 60 can share more load.

[0045] It is appreciated that by arranging the rotor slot 48 and the recess 50 side by side in the circumferential direction C, the bar 58 and the protrusion 60 can occupy a smaller space in the radial direction R, so that the end ring 56 can have a smaller radial width, and thus the squirrel cage rotor 30 can have a smaller weight. In addition, when casting, the side-by-side arrangement of the rotor slot 48 and the recess 50 can concentrate the high-temperature region, so that the lamination is less likely to be deformed by high temperature, and in particular, the effect of the high-temperature region on the inner circumferential portion of the lamination can be weakened.

[0046] It is appreciated that by extending the connecting portion 62 from the end ring 56 into the channel 52, the bar 58 and the protrusion 60 can be connected to the end ring 56 via the connecting portion 62, so that the structural strength of the bar 58 and the protrusion 60 can be improved.

[0047] A manufacturing method of the squirrel cage rotor 30 will be described below, which can include the following steps.

[0048] (i) Positioning the core 32 in a mold.

[0049] (ii) Pouring a molten aluminum alloy liquid (an example of a melt) into the mold.

[0050] (iii) Rotating the mold so that the aluminum alloy liquid fills the rotor slot 48, the recess 50, and the channel 52, wherein the aluminum alloy liquid can flow between the rotor slot 48 and the recess 50 via the channel 52.

[0051] (iv) Solidifying the aluminum alloy liquid to obtain the winding 34.

[0052] (v) Removing the core 32 and the winding 34 from the mold.

[0053] It is appreciated that by allowing the aluminum alloy liquid to flow between the rotor slot 48 and the recess 50, the air in the recess 50 can be taken out with the aluminum alloy liquid, so that the porosity in the protrusion 60 can be reduced or even eliminated. In this way, the protrusion 60 can have a higher structural strength, so that the squirrel cage rotor 30 can have a higher upper limit of rotational speed. Here, the aluminum alloy liquid can flow from the rotor slot 48 into the recess 50, or from the recess 50 into the rotor slot 48. For different channels 52, both flow directions can occur at the same time.

[0054] It is to be understood that, in the above-described casting process, the temperature of the outer circumferential portion of the core 32 is higher than that of the inner circumferential portion. Therefore, the aluminum alloy liquid shrinks more slowly when located at the outer circumferential portion of the core 32 than when located at the inner circumferential portion of the core 32. Accordingly, by extending the channel 52 from the radially outer portion of the rotor slot 48 to the radially outer portion of the recess 50, the aluminum alloy liquid shrinks more slowly when flowing in the channel 52, thereby facilitating feeding and venting.

[0055] It is to be understood that, by covering the entire axial length of the recess 50 with the port 54, the gas located at different positions in the axial direction can all exit the recess 50 along with the flow of the aluminum alloy liquid, thereby facilitating the complete venting of the gas from the recess 50. In addition, the longer port 54 can increase the joint area between the protrusion 60 and the connecting portion 62, thereby further improving the structural strength of the protrusion 60.

[0056] (Second Embodiment)

[0057] The second embodiment is a variation of the first embodiment, and for the features identical or similar to those of the first embodiment, the same reference numerals are used in the present embodiment, and the detailed description of these features is omitted.

[0058] Fig. 9 is a schematic view of the first lamination 36 of the squirrel-cage rotor 30 according to the second embodiment of the present application.

[0059] Compared with the first embodiment, the difference of the present embodiment lies in the different arrangement of the first through-hole 40. Specifically, the first through-hole 40 can still be formed in a substantially U shape, but the bottom of the U shape is changed to be located radially inwardly of the opening of the U shape. Accordingly, the channel 52 can extend from the radially inner portion of the rotor slot 48 to the radially inner portion of the recess 50 along the circumferential direction C.

[0060] It is to be understood that the above-described embodiments are only exemplary and are not intended to limit the present application. Those skilled in the art can make various modifications and changes to the above-described embodiments under the teachings of the present application without departing from the scope of the present application.

[0061] List of Reference Numerals

[0062] 30 squirrel-cage rotor

[0063] 32 core

[0064] 34 winding

[0065] 36 first lamination

[0066] 38 second lamination

[0067] 40 first through-hole

[0068] 42 first portion

[0069] 44 second portion

[0070] 46 second through hole

[0071] 48 rotor slot

[0072] 50 recess

[0073] 52 passage

[0074] 54 port

[0075] 56 end ring

[0076] 58 guide bar

[0077] 60 protrusion

[0078] 62 connecting portion

[0079] A axial direction

[0080] R radial direction

[0081] C circumferential direction

Claims

1. A squirrel cage rotor characterized by, includes: a core (32) defining a rotor slot (48) extending an entire axial length of the core (32), a recess (50) recessed from an axial end surface of the core (32) to an axial inner side at both axial end portions of the core (32), and a passage (52) formed at both axial end portions of the core (32), and the recess (50) communicates with the rotor slot (48) via the passage (52); and a winding (34) integrally molded by casting, the winding (34) including two end rings (56) provided at both axial ends of the core (32), bar conductors (58) protruding into the rotor slot (48) from the end rings (56), protrusions (60) protruding into the recess (50) from the end rings (56), and connecting portions (62) provided in the passage (52), the protrusions (60) being connected to the bar conductors (58) via the connecting portions (62).

2. The squirrel cage rotor of claim 1, wherein, The rotor slot (48) and the recess (50) are arranged side by side in the circumferential direction (C) of the squirrel-cage rotor, and a thickness of the protrusion (60) in the circumferential direction (C) is 1 / 3 to 1 times a thickness of the bar conductor (58) in the circumferential direction (C).

3. The squirrel-cage rotor according to claim 2, wherein the passage (52) extends from a radially outer portion of the rotor slot (48) to a radially outer portion of the recess (50), or the passage (52) extends from a radially inner portion of the rotor slot (48) to a radially inner portion of the recess (50).

4. The squirrel cage rotor of any one of claims 1 to 3, wherein, An axial length of the passage (52) is the same as an axial length of the recess (50), and the connecting portion (62) extends from the end ring (56) to the axial inner side.

5. The squirrel cage rotor of any one of claims 1 to 3, wherein, A plurality of the bar conductors (58) are uniformly distributed in the circumferential direction (C) of the squirrel-cage rotor, and each of the bar conductors (58) is connected to the protrusion (60) via the connecting portion (62) on each side in the axial direction of the squirrel-cage rotor.

6. The squirrel cage rotor of any one of claims 1 to 3, wherein, The core (32) includes a first lamination (36) and a second lamination (38) arranged in layers, the first lamination (36) including a first through-hole (40), the second lamination (38) including a second through-hole (46), the first portion (42) coincides with the second through-hole (46) in the circumferential direction (C) of the squirrel-cage rotor and defines the rotor slot (48) together with the second through-hole (46), the second portion (44) is offset from the second through-hole (46) in the circumferential direction (C) and defines the recess (50) and the passage (52).

7. The squirrel cage rotor of any one of claims 1 to 3, wherein, The passage (52) extends in the circumferential direction (C) of the squirrel-cage rotor, and the passage (52) is provided between the rotor slot (48) and the recess (50), A length of the protrusion (60) in the radial direction (R) of the squirrel-cage rotor is 80% to 120% of a length of the bar (58) in the radial direction (R) of the squirrel-cage rotor.

8. The squirrel cage rotor of any one of claims 1 to 3, wherein, An axial length of each of the protrusion (60) and the connecting portion (62) on each axial side of the squirrel-cage rotor is 1 / 10 to 1 / 30 of an axial length of the bar (58), On the circumferential direction (C) of the squirrel-cage rotor, the adjacent protrusion (60) and the bar (58) are separated by a tooth of the core (32).

9. A method of manufacturing a squirrel cage rotor, characterized by, The squirrel-cage rotor is the squirrel-cage rotor according to any one of claims 1 to 8, and the manufacturing method includes: The melt is caused to flow between the rotor slot (48) and the recess (50) via the passage (52).

10. The method of manufacturing a squirrel cage rotor according to claim 9, wherein The casting is centrifugal casting or die casting, The winding (34) is made of an aluminum alloy.

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