Squirrel-cage rotor and manufacturing method therefor

Abstract

Provided in the present application is a squirrel-cage rotor, comprising an iron core, a winding, and one or more connecting elements, wherein the iron core is provided with slots; the winding is integrally formed by means of casting; the winding comprises end rings, which are arranged at axial ends of the iron core; and the connecting elements are inserted into the slots and extend into the end rings. 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. The end lamination stamping is formed with projections which extend axially beyond the axial end of the rotor core and into the end ring. The projections are combined with the end ring so that they can resist certain centrifugal forces acting on the end ring due to rotation of the rotor.

[0003] However, the thickness of the lamination is usually thin, so that the projection is difficult to bear a large load. In addition, the lamination is easily deformed during stamping, and the stamped lamination is also easily deformed during casting, so that the quality of the electric machine is difficult to guarantee. Furthermore, in order to bend the projection, an additional stamping die needs to be used in the production process, so that the production cost of the electric machine is high.

[0004] SUMMARY

[0005] 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.

[0006] The present application provides a squirrel cage rotor comprising: a core provided with a slot; a winding integrally formed by casting, the winding comprising an end ring provided at an axial end of the core; and one or more connecting elements inserted into the slot and extending into the end ring.

[0007] In an optional aspect, the winding further comprises a plurality of bars supported on the core and connected to each other via the end ring, the plurality of bars being arranged side by side in a circumferential direction of the squirrel cage rotor, the connecting element being arranged between two adjacent bars.

[0008] In another optional aspect, a plurality of the connecting elements are arranged side by side in the circumferential direction of the squirrel cage rotor, the number of the connecting elements being less than the number of the bars.

[0009] In another optional aspect, the connecting element extends into an inner and / or outer circumferential portion of the end ring; and a circumferential dimension of the connecting element is less than or equal to a circumferential dimension of the bar, and a radial dimension of the connecting element is less than or equal to a radial dimension of the bar.

[0010] In another optional solution, the first connecting element and the second connecting element are included as the connecting elements, the first connecting element and the second connecting element are staggered in the circumferential direction of the squirrel cage rotor; and / or the first connecting element and the second connecting element are staggered in the radial direction of the squirrel cage rotor.

[0011] In another optional solution, at a first temperature, the connecting element is configured to be in clearance fit with the slot; and at a second temperature, the connecting element is configured to be in transition fit or interference fit with the slot, wherein the first temperature is lower than the second temperature.

[0012] In another optional solution, the hardness and material strength of the connecting element are greater than the hardness and material strength of the winding.

[0013] In another optional solution, the core includes one or more first laminations and one or more second laminations, the first laminations are provided with through holes, inner circumferential surfaces of the through holes are formed as side walls of the slot, and end surfaces of the second laminations are formed as bottom walls of the slot.

[0014] The application also provides a manufacturing method of the above squirrel cage rotor, the manufacturing method includes: inserting the connecting element into the slot; and casting the winding so that the connecting element extends into the end ring.

[0015] In an optional solution, the casting is centrifugal casting or die casting, and the connecting element is made of stainless steel.

[0016] With the above technical solutions, by providing the connecting element inserted into the slot, the squirrel cage rotor is improved in the following aspects. On the one hand, the size of the connecting element is not easily restricted by the core, so that the connecting element can withstand a larger load, thereby being able to improve the upper limit of the rotation speed of the squirrel cage rotor. On the other hand, the core does not need to be additionally or complexly punched, so that the core is not easily deformed in the punching and casting processes, thereby being conducive to ensuring the quality of the squirrel cage rotor. In addition, since the additional punching step is omitted or simplified in the production process, the production process does not need additional or complex punching dies, so that the squirrel cage rotor can have a lower production cost. BRIEF DESCRIPTION OF DRAWINGS

[0017] FIGS. 1-3 are schematic diagrams of a squirrel cage rotor according to a first embodiment of the application.

[0018] FIG. 4 is a schematic diagram of a first lamination of the squirrel cage rotor in FIG. 1.

[0019] FIG. 5 is a schematic diagram of a second lamination of the squirrel cage rotor in FIG. 1.

[0020] Figs. 6 and 7 are schematic views of the core of the squirrel-cage rotor in Fig. 1.

[0021] Fig. 8 is a schematic view of the squirrel-cage rotor in Fig. 1, in which the windings are omitted.

[0022] Fig. 9 is a sectional view of the squirrel-cage rotor in Fig. 1.

[0023] Fig. 10 is a schematic view of the squirrel-cage rotor in Fig. 1, in which part of the structure is shown in a transparent manner.

[0024] Fig. 11 is a schematic view of a squirrel-cage rotor according to a second embodiment of the present application, in which the windings are omitted.

[0025] Fig. 12 is a schematic view of the squirrel-cage rotor in Fig. 11, in which part of the structure is shown in a transparent manner. DETAILED DESCRIPTION

[0026] Exemplary embodiments of the present application are described below with reference to the accompanying drawings. It is to 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.

[0027] (First Embodiment)

[0028] Figs. 1 to 3 are schematic views of a squirrel-cage rotor 30 according to a first embodiment of the present application.

[0029] The squirrel-cage rotor 30 can include a core 32 and windings 34. The core 32 can include a plurality of first laminations 36 and a plurality of second laminations 38 arranged in a stack in the axial direction. The first laminations 36 can be provided at both axial end portions of the core 32, and the second laminations 38 can be provided at an axial intermediate portion of the core 32. The windings 34 can be made of an aluminum alloy and integrally formed by centrifugal casting. The windings 34 can be cast directly on the core 32, and the core 32 can serve as a part of the casting mold.

[0030] In other embodiments, the windings 34 are not limited to being made of an aluminum alloy, and can be made of a copper alloy, for example. The core 34 is not limited to being integrally formed by centrifugal casting, and can be integrally formed by die casting, for example.

[0031] Fig. 4 is a schematic view of the first lamination 36.

[0032] The first laminations 36 can include a plurality of first through-holes 40 and a plurality of second through-holes 42. The first through-holes 40 can be provided at an outer circumferential portion of the first laminations 36, and the plurality of first through-holes 40 can be arranged side by side and uniformly spaced apart in the circumferential direction C. Each of the second through-holes 42 can be provided between two adjacent first through-holes 40, and the plurality of second through-holes 42 can be arranged side by side and uniformly spaced apart in the circumferential direction C. The number of the first through-holes 40 and the number of the second through-holes 42 can be unequal. For example, in the present embodiment, the number of the first through-holes 40 can be greater than the number of the second through-holes 42. Of course, in other embodiments, the number of the first through-holes 40 and the number of the second through-holes 42 can be equal. The first through-holes 40 and the second through-holes 42 can have substantially the same radial dimension, and the radially inner portion (radially outer portion) of the first through-holes 40 and the radially inner portion (radially outer portion) of the second through-holes 42 can substantially coincide in the radial direction R. In other words, the radially inner portion (radially outer portion) of the first through-holes 40 and the radially inner portion (radially outer portion) of the second through-holes 42 can be located at substantially the same position in the radial direction R.

[0033] FIG. 5 is a schematic view of the second laminations 38.

[0034] The second laminations 38 can include a plurality of third through-holes 44. The third through-holes 44 can be provided at an outer circumferential portion of the second laminations 38, and the plurality of third through-holes 44 can be arranged side by side and uniformly spaced apart in the circumferential direction C. The third through-holes 44 can have substantially the same shape as the first through-holes 40.

[0035] FIGS. 6 and 7 are schematic views of the iron core 32.

[0036] The iron core 32 can include a plurality of rotor slots 46 and a plurality of insertion grooves 48. The rotor slots 46 can extend the entire axial length of the iron core 32, and the insertion grooves 48 can extend from the axial end faces of the iron core 32 toward the axial center side. For adjacent first laminations 36, as viewed in the axial direction A, the first through-holes 40 and the second through-holes 42 on one lamination can respectively coincide with the first through-holes 40 and the second through-holes 42 on the other lamination, so that axial end portions of the rotor slots 46 can be defined by the plurality of first through-holes 40, and side walls of the insertion grooves 48 can be defined by inner circumferential surfaces of the plurality of second through-holes 42. For adjacent second laminations 38, as viewed in the axial direction A, the third through-holes 44 on one lamination can coincide with the third through-holes 44 on the other lamination, so that an axial intermediate portion of the rotor slots 46 can be defined by the plurality of third through-holes 44. For adjacent first laminations 36 and second laminations 38, as viewed in the axial direction A, the first through-holes 40 on the first laminations 36 can coincide with the third through-holes 44 on the second laminations 38, and the axial end faces of the second laminations 38 can cover the entire second through-holes 42, so that the two axial end portions of the rotor slots 46 can communicate via the axial intermediate portion, and a bottom wall of the insertion grooves 48 can be defined by the axial end faces of the second laminations 38.

[0037] Figure 8 is a schematic view of the squirrel cage rotor 30, in which the windings 34 are omitted.

[0038] The squirrel cage rotor 30 can further include a plurality of connecting elements 50. Each connecting element 50 can be inserted into a slot 48, and the axial cross-section of the connecting element 50 and the axial cross-section of the slot 48 can have substantially the same shape and size. The connecting element 50 can abut against the bottom surface of the slot 48, and a portion of the connecting element 50 can protrude out of the slot 48, for example, substantially half of the axial length of the connecting element 50 can protrude out of the slot 48.

[0039] Figures 9 and 10 are schematic views of the squirrel cage rotor 30. Figure 9 shows the squirrel cage rotor 30 in a cutaway manner. The partial structure in Figure 10 is shown in a transparent manner, so as to better observe the connecting elements 50.

[0040] The core 32 can include a pair of end rings 52 and a plurality of bars 54. The end rings 52 can be arranged coaxially with the core 32, and the two end rings 52 can be respectively provided at the two axial ends of the core 32. The bars 54 can be supported on the core 32 and connected between the two end rings 52. Each bar 54 can be provided in a rotor slot 46, and the axial cross-section of the bar 54 and the axial cross-section of the rotor slot 46 can have substantially the same shape and size. Preferably, the circumferential dimension of the connecting element 50 can be less than or equal to the axial dimension of the bar 54, so that the connecting element 50 does not excessively occupy the space of the core 32. The bars 54 can form a certain angle with the axial direction A, so that the bars 54 are inclined. The portion of the connecting element 50 protruding out of the slot 48 can all protrude into the end ring 52, so that the end ring 52 is connected to the core 32 via the connecting element 50. The connecting element 50 and the end ring 52 can have substantially the same radial dimension, so that the connecting element 50 can be arranged on almost the entire radial width of the end ring 52. The hardness and material strength of the connecting element 50 can be greater than the hardness and material strength of the winding 32, for example, the connecting element 50 can be made of stainless steel.

[0041] It needs to be understood that the intersection of the end ring 52 and the bar 54 is prone to stress concentration and forms a weak portion. By providing the connecting element 50, the connecting element 50 can share the load of the bar 54, so that the weak portion is not prone to reaching the yield limit. In this way, the squirrel cage rotor 30 can have a higher upper limit of rotational speed.

[0042] Compared with the prior art, by replacing the protrusion punched out from the laminations with the connecting element 50, the squirrel-cage rotor 30 can be further improved in the following aspects. On the one hand, the size of the connecting element 50 is not easily restricted by the thickness of the laminations, so that the connecting element 50 can bear a larger load, thereby further increasing the upper limit of the rotational speed of the squirrel-cage rotor 30. On the other hand, the laminations do not need to be additionally or complexly punched, so that the laminations are not easily deformed in the punching and casting processes, thereby being conducive to ensuring the quality of the squirrel-cage rotor 30. In addition, since the additional punching step is omitted or simplified in the production process, the production process does not need additional or complex punching dies, so that the squirrel-cage rotor 30 can have a lower production cost.

[0043] It can be understood that by making the hardness and material strength of the connecting element 50 greater than the hardness and material strength of the winding 32, the connecting element 50 can reliably support the end ring 52, so that the end ring 52 can bear a larger load, thereby further increasing the upper limit of the rotational speed of the squirrel-cage rotor 30.

[0044] It can be understood that since the second through hole 42 is arranged between the two adjacent first through holes 40, the connecting element 50 is arranged between the two adjacent conductive bars 54. On the one hand, such an arrangement is conducive to reducing the radial width of the end ring 52, so that the squirrel-cage rotor 30 can have a smaller weight. On the other hand, during the casting process, such an arrangement can make the high-temperature area more concentrated, so that the first laminations 36 and the second laminations 38 are not easily deformed, thereby further improving the quality of the squirrel-cage rotor 30.

[0045] The manufacturing method of the squirrel-cage rotor 30 will be introduced below, and the manufacturing method can include the following steps.

[0046] (i) Inserting the connecting element 50 into the insertion slot 48.

[0047] (ii) Positioning the iron core 32 on which the connecting element 50 is mounted in a mold.

[0048] (iii) Pouring molten aluminum alloy liquid into the mold, so that the aluminum alloy liquid fills the rotor slot 46 and submerges the part of the connecting element 50 protruding from the insertion slot 48, thereby obtaining the winding 34.

[0049] (iv) Removing the iron core 32 and the winding 34 from the mold.

[0050] Here, step (i) can be performed at a lower first temperature so that the slot 48 is clearance-fitted with the connecting member 50, and thus the connecting member 50 is easily inserted into the slot 48. Step (iii) can be performed at a higher second temperature so that the slot 48 is transition-fitted or interference-fitted with the connecting member 50, and thus the connecting member 50 is not easily dislodged from or moved within the slot 48 during casting. Here, the first and second temperatures refer to the temperatures of the core 32 and the connecting member 50. In the present embodiment, in order to achieve such a fitting relationship, the coefficient of thermal expansion of the connecting member 50 can be greater than the coefficients of thermal expansion of the first and second laminations 36 and 38.

[0051] (Second Embodiment)

[0052] The second embodiment is a modification of the first embodiment, and for features that are the same as or similar to those of the first embodiment, the same reference numerals are used in the present embodiment, and detailed descriptions of these features are omitted.

[0053] FIG. 11 is a schematic view of the squirrel-cage rotor 30 according to the second embodiment of the present application, in which the windings 34 are omitted.

[0054] The present embodiment differs from the first embodiment in that the connecting members 50 can have smaller radial dimensions and are arranged on the core 32 in a different manner. Some of the plurality of connecting members 50 can serve as first connecting members 56, and others can serve as second connecting members 58. The first and second connecting members 56 and 58 can be staggered in both the circumferential direction C and the radial direction R. The plurality of first connecting members 56 can be arranged side by side and uniformly spaced in the circumferential direction C, and the plurality of second connecting members 58 can be arranged side by side and uniformly spaced in the circumferential direction C.

[0055] The partial structure in FIG. 12 is shown in a transparent manner in order to better observe the connecting members 50.

[0056] The first connecting members 56 can extend into the inner circumferential portion of the end ring 52, and the second connecting members 58 can extend into the outer circumferential portion of the end ring 52.

[0057] It will be appreciated that the arrangement of the present embodiment enables the size of the second through hole 42 to be reduced compared to the first embodiment, and thus the first lamination 36 is less likely to deform. Furthermore, the squirrel-cage rotor 30 of the present embodiment can have a smaller weight in the case where the number of connecting members 50 is the same.

[0058] The present application is not limited to the above-described embodiments, examples, or configurations, and various modifications can be made to the above-described embodiments, examples, or configurations of the present application by those skilled in the art under the teachings of the present application without departing from the scope of the present application.

[0059] List of Reference Numerals

[0060] 30 squirrel cage rotor

[0061] 32 core

[0062] 34 winding

[0063] 36 first lamination

[0064] 38 second lamination

[0065] 40 first through hole

[0066] 42 second through hole

[0067] 44 third through hole

[0068] 46 rotor slot

[0069] 48 insertion slot

[0070] 50 connecting element

[0071] 52 end ring

[0072] 54 bar

[0073] 56 first connecting element

[0074] 58 second connecting element

[0075] A axial

[0076] R radial

[0077] C circumferential

Claims

1. A squirrel cage rotor characterized by, Comprising: a core (32) provided with a slot (48); a winding (34) integrally formed by casting, the winding (34) including an end ring (52) provided at an axial end of the core (32); and one or more connecting elements (50) inserted into the slot (48) and extending into the end ring (52). The winding (34) further includes a plurality of bars (54) supported on the core (32) and connected to each other via the end ring (52), the plurality of bars (54) being arranged side by side in a circumferential direction (C) of the squirrel cage rotor, the connecting elements (50) being provided between two adjacent bars (54).

2. The squirrel cage rotor of claim 1, wherein, A plurality of the connecting elements (50) are arranged side by side in the circumferential direction (C) of the squirrel cage rotor, the number of the connecting elements (50) being less than the number of the bars (54).

3. The squirrel cage rotor of claim 2, wherein, 4. The squirrel cage rotor according to claim 2, wherein the connecting elements (50) extend into an inner and / or outer circumferential portion of the end ring (52); and a circumferential dimension of the connecting elements (50) is less than or equal to a circumferential dimension of the bars (54), and a radial dimension of the connecting elements (50) is less than or equal to a radial dimension of the bars (54). comprising a first connecting element (56) and a second connecting element (58) as the connecting elements (50), 5. The squirrel cage rotor of any one of claims 1 to 4, wherein, the first connecting element (56) and the second connecting element (58) are staggered in the circumferential direction (C) of the squirrel cage rotor; and / or the first connecting element (56) and the second connecting element (58) are staggered in a radial direction (R) of the squirrel cage rotor.

6. The squirrel cage rotor according to any one of claims 1 to 4, wherein at a first temperature, the connecting elements (50) are configured to be gap-fitted with the slot (48); and at a second temperature, the connecting elements (50) are configured to be transition-fitted or interference-fitted with the slot (48), wherein the first temperature is lower than the second temperature. a hardness and a material strength of the connecting elements (50) are greater than a hardness and a material strength of the winding (34). the core (32) includes one or more first laminations (36) provided with through-holes whose inner circumferential surfaces are formed as side walls of the slot (48), and one or more second laminations (38) whose end surfaces are formed as a bottom wall of the slot (48).

7. The squirrel cage rotor of any one of claims 1 to 4, wherein, The squirrel cage rotor is the squirrel cage rotor according to any one of claims 1 to 8, and the manufacturing method includes:

8. The squirrel cage rotor of any one of claims 1 to 4, wherein, inserting the connecting elements (50) into the slot (48); and 9. A method of manufacturing a squirrel cage rotor, characterized by, casting the winding (34) such that the connecting elements (50) extend into the end ring (52). The casting is centrifugal casting or die casting, and the connecting elements (50) are made of stainless steel. ​ 10. The method of manufacturing a squirrel cage rotor according to claim 9, wherein ​

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