Rotor for an asynchronous electric machine

Abstract

A rotor for an asynchronous electric machine, the rotor comprising a rotor lamination stack having a plurality of slots extending axially through the rotor lamination stack distributed uniformly around a circumference, and a cast rotor cage having a plurality of bars extending through the slots of the rotor lamination stack, respectively, and short-circuit rings adjoining end faces of the rotor lamination stack and connecting the bars, wherein the lamination stack has a plurality of rotor laminations stacked axially on top of one another, the rotor laminations each having a plurality of recesses distributed uniformly around the circumference for forming the respective slots, wherein the rotor laminations each can be assigned to at least two different lamination types, namely a first lamination type having elongated, radially extending first recesses or a second lamination type having elongated, radially extending second recesses, wherein the radial extension of the first recesses is smaller than the radial extension of the second recesses.

Description

Technical Field

[0001] The present invention relates to a rotor for an asynchronous motor, the rotor comprising a rotor lamination assembly and a cast rotor cage, the rotor lamination assembly comprising a plurality of slots circumferentially distributed and extending axially through the lamination assembly, the rotor cage having a plurality of cage bars extending through the slots of the rotor lamination assembly respectively, and short-circuit rings adjacent to the end faces of the rotor lamination assembly and connecting the cage bars. Background Technology

[0002] Asynchronous motors are primarily used as drive motors and / or generators in electric or hybrid vehicles. Generally, an asynchronous motor has a stator and a rotor rotatable relative to the stator. Here, the rotor is configured as a so-called short-circuit rotating element, which has a cage made of a highly conductive material, such as aluminum or copper, or alloys of these materials.

[0003] The rotor cage is typically located at the rotor lamination assembly and has short-circuit bars and short-circuit rings extending longitudinally, the short-circuit rings connecting the ends of the short-circuit bars to each other. Conventionally, the short-circuit cage is either manufactured by casting, in which molten metal is filled into a mold surrounding the rotor body and flows into grooves provided in the rotor body to form the short-circuit bars, and simultaneously flows into cavities provided at the end faces of the rotor body to form the short-circuit rings. Alternatively, the rotor cage may also consist of multiple bars and separate short-circuit rings, wherein these components are subsequently electrically connected to each other, for example by brazing, fusion welding, etc.

[0004] To enable asynchronous motors to operate at higher speeds and thus increase their power density, development has focused particularly on improving the load-bearing capacity of the short-circuit ring, which is subjected to strong centrifugal forces at high speeds, potentially damaging or, in the worst cases, destroying the rotor. However, such improvements to the load-bearing capacity of the short-circuit ring typically come with additional components and / or costly installation processes and tooling requirements. Summary of the Invention

[0005] The object of the present invention is to provide a rotor for an asynchronous motor, characterized in particular by improving the load-bearing capacity of the short-circuit ring with less component consumption and manufacturing cost.

[0006] The objective is achieved by a rotor for an asynchronous motor having features according to the invention.

[0007] According to the present invention, the rotor has a rotor lamination assembly and a cast rotor cage, the rotor lamination assembly including a plurality of slots evenly distributed around the circumference and extending axially through the lamination assembly, the rotor cage having a plurality of cage bars extending through the slots of the rotor lamination assembly respectively and short-circuit rings adjacent to the end face of the rotor lamination assembly and connecting the cage bars.

[0008] The direction specification “axial” describes the direction along or parallel to the central rotor axis of the rotor.

[0009] The term "circumference" describes the direction of the outer circumference following the rotor or the direction of the outer circumference of the rotor laminations.

[0010] According to the present invention, the rotor lamination assembly has a plurality of rotor laminations stacked axially on top of each other, each rotor lamination having a plurality of circumferentially distributed voids for forming corresponding slots extending axially through the rotor lamination assembly.

[0011] According to the present invention, the rotor laminations can be respectively assigned to at least two different lamination types, namely, a first lamination type having an elongated first void extending in the radial direction, or a second lamination type having an elongated second void extending in the radial direction, wherein the radial extension of the first void is less than the radial extension of the second void. It is also conceivable, for example, to form a third lamination type that can be assigned to at least one rotor lamination, wherein the third lamination type has both a first void and a second void.

[0012] The direction description "radial" refers to the direction perpendicular to the central rotor axis.

[0013] According to the present invention, in the rotor lamination group, in the axial direction, at least a plurality of rotor laminations of the second lamination type, then at least a plurality of rotor laminations of the first lamination type, and then at least a plurality of rotor laminations of the second lamination type are stacked on top of each other, such that at least in the end region of the rotor lamination group, i.e. near the end face, i.e. near the respective end face of the rotor lamination group, a first support shoulder is formed in a respective slot.

[0014] The "end face" is basically formed by the bottom and top surfaces of the cylindrical or hollow cylindrical rotor lamination assembly.

[0015] By employing the rotor configuration according to the invention, particularly by creating a stepped design for the slots in the rotor laminations, a significant reduction in rotor damage, such as the risk of irreversible deformation of the short-circuit ring, can be achieved at higher speeds, thereby enabling reliable operation of the asynchronous motor at the highest possible power density.

[0016] Furthermore, the second void is preferably configured such that its width, following the circumferential direction, begins from the outer circumference of the rotor laminations, decreases radially over a defined length, and then increases again over the defined length, thereby creating at least one additional second support shoulder. This design of the second void, i.e., by creating the second support shoulder, achieves an additional improvement in the mechanical load-bearing capacity of the asynchronous motor rotor in a simple manner.

[0017] The radial extension of the corresponding void preferably corresponds to a minimum of 4% to a maximum of 22% of the outer diameter of the corresponding rotor lamination.

[0018] The radial distance between the corresponding empty portion and the central empty portion of the corresponding rotor lamination preferably corresponds to at least twice the thickness of the corresponding rotor lamination, i.e. twice the axial extension.

[0019] The radial distance between the corresponding empty portion and the outer circumference of the corresponding rotor lamination is preferably at least twice the thickness of the corresponding rotor lamination, i.e. twice the axial extension.

[0020] In a favorable configuration of the rotor, the short-circuit ring is made of aluminum or copper.

[0021] The rotor configuration according to the invention enables improved manufacturing of an asynchronous motor with a cast rotor cage. The rotor is particularly characterized by improved load-bearing capacity of the short-circuit ring of the cast rotor cage with reduced component and manufacturing costs. Attached Figure Description

[0022] Embodiments of the present invention will now be described with reference to the accompanying drawings, which should not be construed as limiting the invention. The drawings are schematic only and are not drawn to scale. In the drawings, the same reference numerals denote the same or equivalent features.

[0023] Figure 1 A perspective view of the rotor laminations for an asynchronous motor is shown.

[0024] Figure 2a Showing according to Figure 1 A top view of the first end face of the rotor lamination assembly.

[0025] Figure 2b Show Figure 2a The detail view of a local C in the image.

[0026] Figure 3a Showing according to Figure 1 A top view of the second end face of the rotor lamination assembly.

[0027] Figure 3b Show Figure 3a The detail view of local area B in the image.

[0028] Figure 4 Show along according to Figure 2a The sectional view of section AA.

[0029] Figure 5a A top view of rotor laminations of the first lamination type is shown.

[0030] Figure 5b Show Figure 5a The detailed view of a local D in the image.

[0031] Figure 6a A top view of rotor laminations of the second lamination type is shown.

[0032] Figure 6b Show Figure 6a The detailed view of a local E in the image. Detailed Implementation

[0033] exist Figure 1 The figure shows a perspective view of the rotor lamination assembly 1 of the rotor of the asynchronous motor according to the invention. For clarity, the cast rotor cage of the rotor according to the invention is not shown in the figure.

[0034] The rotor lamination assembly 1 is substantially hollow and cylindrical, having a central opening 9 for accommodating a rotor shaft (not shown). The rotor lamination assembly 1 has a plurality of thin, sheet-like rotor laminations 3 stacked axially on top of each other. Each rotor lamination 3 is configured to have a circular outer circumference and a similarly circular central void 7. Furthermore, in this embodiment, each rotor lamination 3 has a plurality of voids 4 evenly distributed around its circumference, i.e., a plurality of first voids 4a or a plurality of second voids 4b evenly distributed around its circumference.

[0035] The direction specification "axial" describes the direction along or parallel to the central rotor axis 8 of the rotor. The direction specification "radial" describes the direction perpendicular to the central rotor axis 8 of the rotor.

[0036] Currently, each rotor lamination 3 can be assigned to either a first lamination type 3a or a second lamination type 3b, wherein the configurations of the uniformly distributed circumferential voids 4 of the two lamination types 3a and 3b are significantly different. The rotor lamination 3 of the first lamination type 3a has multiple elongated, radially extending first voids 4a uniformly distributed circumferentially. The rotor lamination 3 of the second lamination type 3b has multiple, corresponding to the number of first voids 4a, elongated, radially extending second voids 4b uniformly distributed circumferentially. The radial extension of the first voids 4a is less than the radial extension of the second voids 4b.

[0037] The rotor laminations 3 of the first lamination type 3a and the second lamination type 3b are axially stacked such that the first empty portion 4a and the second empty portion 4b are aligned with each other, thereby forming slots 2 that extend axially in the longitudinal direction of the rotor lamination group 1 and are spaced apart from each other in the circumferential direction U of the rotor lamination group 1. The slots 2 are mainly used to accommodate the cage bars (not shown) of the rotor cage.

[0038] Rotor lamination group 1 in Figures 1 to 4The embodiments shown in varying degrees of detail are constructed by axially stacking multiple rotor laminations 3 of the second lamination type 3b, followed by axially stacking multiple rotor laminations 3 of the first lamination type 3a, and then axially stacking multiple rotor laminations 3 of the second lamination type 3a. In this way, first support shoulders 5 are formed in the corresponding slots 2 in the end regions of the rotor lamination group 1, i.e., near the end face.

[0039] The term "near the end face" describes the region near either the first end face S1 or the second end face S2 of the rotor lamination assembly 1. The first end face S1 currently forms the bottom surface of the hollow cylindrical rotor lamination assembly 1; the second end face S2 currently forms the top surface of the hollow cylindrical rotor lamination assembly 1.

[0040] exist Figure 5a and Figure 5b The rotor laminations 3 of the first lamination type 3a are shown in varying degrees of detail. A first gap 4a is configured such that its width follows the circumferential direction U from the outer circumference U of the corresponding rotor lamination 3 of the first lamination type 3a. A Initially, it decreases radially over a defined length.

[0041] exist Figure 6a and Figure 6b The rotor laminations 3 of the second lamination type 3b are shown in varying degrees of detail. The second gap 4b is configured such that its width follows the circumferential direction U from the outer circumference U of the corresponding rotor lamination 3 of the second lamination type 3b. A Initially, the length is reduced radially and then increased again over the defined length. This allows for the generation of additional support shoulders, namely second support shoulders 6, through the axial stacking of multiple rotor laminations 3 of the second lamination type 3b.

[0042] The outer diameter D of the rotor lamination 3 of the first lamination type 3a is... A and outer ring U A The outer diameter D of the rotor lamination 3 corresponding to the second lamination type 3b A and outer ring U A Therefore, the outer diameter D of rotor lamination group 1 A and outer ring U A The outer diameter D corresponds to the rotor laminations 3, 3a, and 3b that are stacked vertically on top of each other in the axial direction. A and outer ring U A .

[0043] List of reference numerals

[0044] 1 rotor lamination group

[0045] 2 slots

[0046] 3 rotor laminations

[0047] 3a First lamination type (rotor lamination of the first lamination type)

[0048] 3b Second lamination type (rotor lamination of the second lamination type)

[0049] 4. Empty space

[0050] 4a First blank section

[0051] 4b Second blank section

[0052] 5. First support shoulder

[0053] 6 Second support shoulder

[0054] 7 (The corresponding rotor laminations) Central void

[0055] 8 (The rotor's) central axis of rotation

[0056] 9 (Central opening of rotor laminations)

[0057] S1 (first end face of rotor lamination assembly)

[0058] S2 (the second end face of the rotor lamination assembly)

[0059] D A (The outer diameter of the corresponding rotor laminations or rotor lamination groups)

[0060] U A (The outer circumference of the corresponding rotor laminations or rotor lamination groups)

[0061] U (the circumferential direction of the corresponding rotor laminations or rotor lamination groups)

Claims

1. A rotor for an asynchronous motor, the rotor comprising a rotor lamination assembly (1) and a cast rotor cage, the rotor lamination assembly having a plurality of slots (2) axially extending through the rotor lamination assembly (1) and evenly distributed around its circumference, the rotor cage having a plurality of cage bars extending through the slots (2) of the rotor lamination assembly (1) and short-circuit rings adjacent to the end faces (S1, S2) of the rotor lamination assembly (1) and connecting the cage bars, wherein the rotor lamination assembly (1) has a plurality of rotor laminations (3) axially stacked on top of each other, each rotor lamination having a plurality of circumferentially distributed voids (4) for forming corresponding slots (2), wherein each rotor lamination (3) is capable of being assigned to at least two different lamination types (3a, 3b), namely a first lamination type (3a) having an elongated first void (4a) extending in the radial direction or a second lamination type (3b) having an elongated second void (4b) extending in the radial direction. (b) wherein the radial extension of the first empty portion (4a) is less than the radial extension of the second empty portion (4b), and wherein in the rotor lamination group (1), in the axial direction, at least a plurality of rotor laminations (3) of the second lamination type (3b), then at least a plurality of rotor laminations (3) of the first lamination type (3a) and then at least a plurality of rotor laminations (3) of the second lamination type (3b) are stacked on top of each other, such that at least in the region at the end of the rotor lamination group (1), i.e. near the end face, a first support shoulder (5) is formed in the corresponding slot (2).

2. The rotor according to claim 1, Its features are, The second empty portion (4b) is configured such that its width follows the circumferential direction (U) from the outer circumference (U) of the corresponding rotor lamination (3) of the second lamination type (3b). A (6) Begins radially decreasing over a defined length and then increasing again over the defined length, thereby creating at least one additional second support shoulder.

3. The rotor according to claim 1 or 2, Its features are, The radial extension of the corresponding empty portions (4, 4a, 4b) corresponds to the outer diameter (D) of the corresponding rotor laminations (3, 3a, 3b). A (The minimum is 4% and the maximum is 22%).

4. The rotor according to claim 1, 2 or 3, Its features are, The radial distance between the corresponding empty portion (4, 4a, 4b) and the central empty portion (7) of the corresponding rotor lamination (3, 3a, 3b) corresponds to at least twice the thickness of the corresponding rotor lamination (3, 3a, 3b), i.e. twice the axial extension.

5. The rotor according to any one of claims 1 to 4, Its features are, The corresponding empty portions (4, 4a, 4b) are located at a distance from the outer circumference (U) of the corresponding rotor laminations (3, 3a, 3b). A The radial spacing of the rotor laminations (3, 3a, 3b) corresponds to at least twice the thickness, i.e. twice the axial extension, of the corresponding rotor laminations (3, 3a, 3b).

6. The rotor according to any one of the preceding claims, Its features are, The short-circuit ring is made of aluminum or copper.

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