Squirrel cage rotor

Abstract

The invention provides a squirrel cage rotor which comprises an iron core (10) and a squirrel cage (20) formed through casting, the squirrel cage (20) comprises a plurality of conducting bars (21) and two end rings (22) located at the two ends of the conducting bars (21), and the iron core (10) comprises a first section (11) located in the axial middle and two additional sections distributed at the two ends of the first section (11). A plurality of first grooves (110) are formed in the first section (11), a plurality of additional grooves are formed in the additional section, the guide strip (21) comprises a guide strip middle section (211) formed in the first groove (110) and a guide strip large end formed in the additional groove, and the outline of the guide strip large end is larger than that of the guide strip middle section (211) on a projection perpendicular to the axial direction. The squirrel cage rotor is high in structural strength and not prone to deformation at a high rotating speed.

Description

Technical Field

[0001] The present invention relates to the field of motors, and more particularly to a squirrel cage rotor of a motor. Background Art

[0002] High-speed motors are increasingly being used in many fields, such as in new energy vehicles. For squirrel cage rotors, such as cast aluminum squirrel cage rotors, the structural strength of the connection between the cage bars and the end rings is usually a weak point, especially when the motor speed is greater than 20,000 rpm or even reaches 25,000 rpm, the requirements for the strength of the cage structure will be very high. Summary of the invention

[0003] The purpose of the present invention is to overcome or at least alleviate the deficiencies of the above-mentioned prior art and to provide a high-speed squirrel cage rotor with low cost and high structural strength.

[0004] The present invention provides a squirrel cage rotor, which comprises an iron core and a squirrel cage formed by casting, wherein the squirrel cage comprises a plurality of conducting bars and two end rings located at both ends of the conducting bars. The core includes a first section located in the middle of the axial direction and two additional sections distributed at both ends of the first section, the first section is formed with a plurality of first slots, and the additional sections are formed with a plurality of additional slots. The guide bar comprises a guide bar middle section formed in the first slot and a guide bar large end formed in the additional slot, On a projection plane perpendicular to the axial direction, the contour of the large end of the conductor bar is larger than the contour of the middle section of the conductor bar.

[0005] In at least one embodiment, the additional section includes a second section, the second section is formed with a plurality of second slots, and on a projection plane perpendicular to the axial direction, the second slots extend beyond the first slots on a radially inner side of the core.

[0006] In at least one embodiment, on a projection plane perpendicular to the axial direction, the second groove also exceeds the first groove on both sides in the circumferential direction.

[0007] In at least one embodiment, the additional section further comprises a reinforcing sheet, and the reinforcing sheet is located on a side of the second section facing away from the first section. The reinforcing sheet is formed with a plurality of openings, and on a projection plane perpendicular to the axial direction, an outline of each of the openings covers an outline of a plurality of the second grooves.

[0008] In at least one embodiment, the additional section is a reinforcement sheet, and the reinforcement sheet is formed with a plurality of openings. On a projection plane perpendicular to the axial direction, an outline of each of the openings covers an outline of a plurality of the first grooves.

[0009] In at least one embodiment, in a projection perpendicular to the axial direction, the opening extends beyond the first slot on the radial inner side of the core.

[0010] In at least one embodiment, the reinforcing sheet is made of a material having a yield strength greater than a yield strength of a material made of the first section.

[0011] In at least one embodiment, on a cross section perpendicular to the axial direction, the profile of the additional section forms a concave-convex uneven structure on both sides of the circumference, so that the large end of the conductive bar forms a concave-convex structure in the circumferential direction.

[0012] In at least one embodiment, an outer peripheral portion of the end ring forms a slope surface.

[0013] In at least one embodiment, the casting material of the cage is pure aluminum.

[0014] The squirrel cage rotor according to the present invention has high structural strength and is not easily deformed at high rotation speeds. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of a squirrel cage rotor according to a first embodiment of the present application.

[0016] Figure 2 yes Figure 1 Schematic diagram of the corresponding core.

[0017] Figure 3 yes Figure 2 Schematic diagram of the corresponding core with the reinforcement sheet hidden.

[0018] Figure 4 yes Figure 1 Schematic diagram of the first section of the corresponding core.

[0019] Figure 5 yes Figure 1 Schematic diagram of the corresponding squirrel cage cut along the axial direction.

[0020] Figure 6 yes Figure 5 A locally enlarged schematic diagram.

[0021] Figure 7 yes Figure 1 Axial view of the first section of the corresponding core.

[0022] Figure 8 yes Figure 1 Axial view of the second section of the corresponding core.

[0023] Fig. 9 yes Figure 7The corresponding first section and Figure 8 Axial view of the corresponding second segment superposition.

[0024] Fig.10 yes Figure 1 Schematic diagram of the corresponding core reinforcement sheet.

[0025] Fig.11 yes Fig.10 Axial view of .

[0026] Fig.12 yes Figure 8 The corresponding second section and Fig.11 Axial view of the corresponding reinforcement sheet stack.

[0027] Fig.13 yes Figure 7 The corresponding first section, Figure 8 The corresponding second segment overlaps and Fig.11 Axial view of the corresponding reinforcement sheet.

[0028] Fig.14 1 is an axial view of a first section of an iron core and a stack of reinforcement sheets of a squirrel cage rotor according to a second embodiment of the present application.

[0029] Fig.15 is a schematic diagram of a squirrel cage rotor according to a third embodiment of the present application.

[0030] Fig.16 yes Fig.15 Schematic diagram of the corresponding squirrel cage rotor cut along the axial direction.

[0031] Fig.17 yes Fig.15 Schematic diagram of the corresponding squirrel cage rotor core.

[0032] Fig.18 yes Fig.15 Schematic diagram of the corresponding first section of the iron core.

[0033] Fig.19 yes Fig.17 The corresponding axial view of the core.

[0034] Fig. 20 yes Fig.17 Axial view of the corresponding second section.

[0035] Fig.21 yes Fig. 20 A partially enlarged schematic diagram of the corresponding second section.

[0036] Fig. 22 yes Fig.15 Schematic diagram of the squirrel cage of the corresponding squirrel cage rotor.

[0037] Fig.23 yes Fig. 22 Schematic diagram of a section perpendicular to the axial direction.

[0038] Fig.24 yes Fig. 22 Schematic diagram of an axial section.

[0039] Description of reference numerals: 10 iron core; 11 first section; 110 first slot; 12 second section; 120 second groove; 121 second groove outer portion; 122 second groove inner portion; 13 reinforcing sheet; 130 opening; 131 outer peripheral portion of the opening; 132 inner peripheral portion of the opening; 20 squirrel cage; 21 guide bar; 211 middle section of guide bar; 212 end section of guide bar; 2121 convex part; 2122 concave part; 2123 inner extension; 213 guide bar reinforcement section; 22 end ring; 220 slope surface. DETAILED DESCRIPTION

[0040] The exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present invention, and are not intended to exhaust all possible modes of the present invention, nor to limit the scope of the present invention.

[0041] First embodiment Reference Figures 1 to 13 , a squirrel cage rotor according to a first embodiment of the present application is introduced. Unless otherwise specified, the radial, axial and circumferential directions of each component referred to below are all based on the radial, axial and circumferential directions of the iron core of the squirrel cage rotor.

[0042] Reference Figure 1 The squirrel cage rotor of this embodiment includes an iron core 10 and a squirrel cage 20. The squirrel cage 20 is formed by casting, and the material used for casting is preferably a material with high electrical conductivity, such as pure aluminum (aluminum content is not less than 99%), which has low material cost and good electrical conductivity.

[0043] Figure 2 The iron core 10 is shown, which includes a first section 11 , a second section 12 located at two axial ends of the first section 11 , and two reinforcing sheets 13 located at two ends of the second section 12 facing away from the first section 11 . Figure 3 The reinforcing sheet 13 is omitted and the first section 11 and the second section 12 are shown stacked. Figure 4 Only the first section 11 is shown.

[0044] Among them, the first section 11 and the second section 12 can both be formed by stacking silicon steel sheets; the reinforcement sheet 13 is preferably a metal plate with a thickness greater than that of a single silicon steel sheet, and the thickness of the reinforcement sheet 13 is, for example, 1~20mm, preferably 3~5mm; the material yield strength of the reinforcement sheet 13 is greater than that of the silicon steel sheet, and the manufacturing material of the reinforcement sheet 13 is, for example, DC mold steel.

[0045] The first section 11, the second section 12 and the reinforcing sheet 13 form grooves of different sizes, and the guide bars 21 of the squirrel cage 20 are formed in these grooves, so that the guide bars 21 show a segmented structure in the axial direction. In this embodiment, the whole formed by the second section 12 and the reinforcing sheet 13 is also called an additional section. Figures 5 and 6 The squirrel cage 20 is shown in an axially cutaway state.

[0046] Next, combine Figures 7 to 13 , the structure of the different sections in the core 10 and the structure of the squirrel cage formed therewith are described in detail.

[0047] First combine Figures 7 to 9 The first section 11 forms a plurality of first grooves 110, in which the main part of the conductor bar 21, namely the conductor bar middle section 211, is cast. The second section 12 forms a plurality of second grooves 120, in which the conductor bar end section 212 of the conductor bar 21 is cast. Fig. 9 The axial projection of the first section 11 and the second section 12 when they are stacked together is shown. It can be seen from the figure that the circumferential center line of each first groove 110 is aligned with the circumferential center line of a second groove 120, the second groove 120 exceeds the first groove 110 in the radial direction, and the radially inner portion exceeds the first groove 110 on both sides of the circumference. The second groove 120 includes a second groove outer portion 121 close to the outer circumference and a second groove inner portion 122 close to the inner circumference. Each second groove outer portion 121 is substantially aligned with a first groove 110, the second groove inner portion 122 exceeds the first groove 110 in the radial direction, and the second groove inner portion 122 exceeds the first groove 110 in the circumferential direction at the portion connected with the second groove outer portion 121. As a result, the casted conductor bar end 212 exceeds the conductor bar middle section 211 in the radial direction, and the exceeding portion also slightly exceeds the conductor bar middle section 211 on both sides of the circumference.

[0048] According to the above description, the junction of the guide bar 21 and the end ring 22 is the weak point of the cage structure, and the guide bar end 212 is close to this structural weakness. Forming a guide bar end 212 with a larger cross-sectional area at this point will disperse the structural stress near the junction. The width change at the junction of the second slot outer portion 121 and the second slot inner portion 122 plays a role similar to an "anchor". When the rotor moves at high speed and the cage is subjected to centrifugal force, the tendency of the second slot inner portion 122 to move toward the outer peripheral side will be constrained by the iron core.

[0049] Next, combine Figures 10 to 13 The reinforcing sheet 13 and the conductor bar reinforcing section 213 formed in the reinforcing sheet 13 by casting are introduced.

[0050] The reinforcing sheet 13 is formed with a plurality of openings 130 . Fig.11 is an axial view of the reinforcing sheet 13, Fig.12 The figure shows the projection along the axial direction when the reinforcing sheet 13 and the second section 12 are stacked together. Fig.13 The figure shows the projection of the reinforcing sheet 13, the second section 12 and the first section 11 when they are stacked together in the axial direction. It can be seen that each opening 130 can cover multiple (two in this embodiment, and in other possible embodiments, three to five or even more) second grooves 120. The opening 130 includes an opening outer peripheral portion 131 close to the outer peripheral side and an opening inner peripheral portion 132 close to the inner peripheral side. The opening outer peripheral portion 131 is aligned with the second groove outer side portion 121 in the radial direction, and the opening inner peripheral portion 132 is aligned with the second groove inner side portion 122 in the radial direction. In accordance with the shape of the second groove outer side portion 121 and the second groove inner side portion 122, at the junction of the opening inner peripheral portion 132 and the opening outer peripheral portion 131, the opening inner peripheral portion 132 exceeds the opening outer peripheral portion 131 on both sides in the circumferential direction.

[0051] The conductor bar reinforcement section 213 is cast at the opening 130, and the conductor bar reinforcement section 213 directly connects the conductor bar end 212 and the end ring 22. From the axial middle of the squirrel cage to the two ends, there are the conductor bar middle section 211, the conductor bar end 212, the conductor bar reinforcement section 213 and the end ring 22, and the cross-sectional area of ​​the conductor bar part is getting larger and larger. In this embodiment, the whole formed by the conductor bar end 212 and the conductor bar reinforcement section 213 is also called the conductor bar big end.

[0052] Similar to the function of the conductor bar end 212, the conductor bar reinforcement section 213 itself is located at the weakest position of the cage structure, and the conductor bar reinforcement section 213 has a larger axial cross-sectional area than the conductor bar end 212, so that the stress at this location is dispersed. The width change at the junction of the opening outer peripheral portion 131 and the opening inner peripheral portion 132 plays a role similar to an "anchor". When the rotor moves at high speed and the cage is subjected to centrifugal force, the tendency of the opening inner peripheral portion 132 to move toward the outer peripheral side will be constrained by the iron core.

[0053] In addition, since the reinforcing sheet 13 has a high structural strength, the deformation of the inner guide bar portion is further limited, so that the squirrel cage can still maintain its original shape at a high speed without being deformed due to centrifugal force.

[0054] Back to Figure 5The end ring 22 forms a slope surface 220 at the outer peripheral portion, which achieves the effect of reducing the weight of the outer peripheral area of ​​the end ring 22, thereby reducing the centrifugal force on the end ring 22. During the high-speed rotation of the rotor, the stress between the end ring 22 and the guide bar 21 is further reduced.

[0055] Second embodiment Reference Fig.14 The second embodiment of the present application is introduced. The second embodiment is a modification of the first embodiment, and components having the same or similar structures or functions as those in the first embodiment are marked with the same reference numerals, and detailed descriptions of these components are omitted.

[0056] The main difference between this embodiment and the first embodiment is that the core 10 of this embodiment only includes the first section 11 and the reinforcement sheet 13 , and the second section 12 is not disposed between the first section 11 and the reinforcement sheet 13 .

[0057] Fig.14 1 is a schematic axial projection diagram when the reinforcing sheet 13 and the first section 11 are stacked together, and only the iron core 10 is shown in the figure, but not the squirrel cage 20. It can be understood that the conductor bar 21 of the squirrel cage 20 formed by casting the iron core 10 only includes the conductor bar middle section 211 and the conductor bar reinforcing section 213, but does not include the conductor bar end 212. For this embodiment, the reinforcing sheet 13 is also called an additional section, and the conductor bar reinforcing section 213 is called a conductor bar big end.

[0058] In this embodiment, on the projection plane perpendicular to the axial direction, the contour of each opening 130 of the reinforcing sheet 13 covers the contours of the plurality of first grooves 110, and the opening 130 exceeds the first groove 110 in the radial direction, and the exceeding portion is the opening inner circumference 132. The opening inner circumference 132 and the opening outer circumference 131 form a change in the opening width at the junction, and the circumferential width of the opening inner circumference 132 at the junction is greater than that of the opening outer circumference 131.

[0059] The conductor bar reinforcement section 213 in this embodiment directly connects the conductor bar middle section 211 and the end ring 22. As the area where the original structural strength may be the weakest, the conductor bar reinforcement section 213 in this embodiment increases the cross-sectional area of ​​the connection, and the width change at the junction of the opening outer peripheral portion 131 and the opening inner peripheral portion 132 plays a role similar to an "anchor". When the rotor moves at high speed and the squirrel cage is subjected to centrifugal force, the tendency of the opening inner peripheral portion 132 to move toward the outer peripheral side will be constrained by the iron core.

[0060] Third embodiment Reference Figures 15 to 24 The third embodiment of the present application is introduced. The third embodiment is another variation of the first embodiment.

[0061] The main difference between this embodiment and the first embodiment is that the core 10 in this embodiment does not have the reinforcing sheet 13 , but the structural strength of the cage 20 is increased by improving the shape of the second slot 120 of the second section 12 .

[0062] The core 10 in this embodiment includes a first section 11 and two second sections 12 located at both ends of the first section 11. The first section 11 is formed with a plurality of first slots 110, and the second section 12 is formed with a plurality of second slots 120. Fig.19 The axial projection of the first section 11 and the second section 12 when they are stacked together is shown. Similar to the first embodiment, the circumferential center line of each first groove 110 is aligned with the circumferential center line of a second groove 120, and the second groove 120 extends radially inward beyond the first groove 110, and the extending portion is the inward extension portion 2123.

[0063] Also refer to Fig.21 The profile of the second groove 120 forms a concave-convex uneven structure on both sides of the circumferential direction, or the second groove 120 includes a plurality of convex portions 2121 and a plurality of concave portions 2122 in the circumferential direction. In the radial direction, these convex portions 2121 and concave portions 2122 are not limited to being located in the conductor bar reinforcement section 213 or the non-conductor bar reinforcement section. These concave-convex structures make the conductor bar end 212 of the conductor bar 21 cast through the second groove 120 also have a concave-convex shape in the circumferential direction.

[0064] The bar reinforcement section 213 at the connection between the bar 21 and the end ring 22 in this embodiment has a larger cross-sectional area, which disperses the stress at the connection. The uneven shape of the bar end 212 plays a role similar to a hook, increasing the friction between the bar 21 and the core 10, so that the cage 20 can withstand greater centrifugal force without deformation during the high-speed rotation of the rotor.

[0065] In this embodiment, the second section 12 is also called an additional section, and the conductor bar end 212 is called a conductor bar big end.

[0066] It should be understood that the above embodiments and some aspects or features thereof may be appropriately combined. For example, the conductor bar end 212 in the first embodiment may also have a convex portion 2121 and a concave portion 2122, or the conductor bar reinforcement section 213 in the second embodiment may also include a plurality of convex portions and a plurality of concave portions in the circumferential direction.

[0067] The present invention has at least one of the following advantages: (i) The squirrel cage of the present application is provided with a large end of the guide bar with a larger cross-sectional area between the middle section of the guide bar and the end ring, so that the stress of the original weak part of the structure of the squirrel cage is dispersed, thereby enhancing the structural strength of the squirrel cage; and the large end of the guide bar is located radially inward of the middle section of the guide bar compared to the enlarged part of the middle section of the guide bar, and the centrifugal force on this part is relatively small, and the centrifugal force increased by the squirrel cage is limited at high speed of the motor.

[0068] (ii) When the cross-sectional area of ​​the large end of the conductor bar is increased, a concave-convex structure can be provided to increase the friction between the cage and the core, so that the cage can withstand greater centrifugal force without deformation.

[0069] (iii) The iron core may include a reinforcing sheet. On the one hand, the reinforcing sheet may be made of a material having a yield strength greater than that of the silicon steel sheet so as to increase the structural strength of the iron core. On the other hand, the opening of the reinforcing sheet covers a plurality of first slots or second slots adjacent thereto, so that the conductor bar reinforcement section cast in the opening is connected to the end ring and a plurality of conductor bar middle sections or a plurality of conductor bar end sections at both axial ends with a larger cross-sectional area, thereby further reducing the structural stress at the connection between the conductor bar and the end ring and enhancing the structural strength of the squirrel cage.

[0070] (iv) The outer peripheral portion of the end ring forms a slope surface, which achieves the effect of reducing the weight of the outer peripheral area of ​​the end ring, thereby reducing the centrifugal force on the end ring.

[0071] (v) Since the structural strength of the squirrel cage is enhanced, the casting material of the squirrel cage can be selected from a material with high electrical conductivity and low strength, such as pure aluminum, thereby reducing the material cost, increasing the power density of the rotor, and not affecting the reliability of the rotor.

[0072] Of course, the present invention is not limited to the above-mentioned embodiments, and those skilled in the art may make various modifications to the above-mentioned embodiments of the present invention under the guidance of the present invention without departing from the scope of the present invention.

Claims

1. A squirrel cage rotor, comprising an iron core (10) and a squirrel cage (20) formed by casting, wherein the squirrel cage (20) comprises a plurality of conductive bars (21) and two end rings (22) located at both ends of the conductive bars (21), characterized in that: The iron core (10) comprises a first section (11) located in the middle of the axial direction and two additional sections distributed at both ends of the first section (11), the first section (11) being formed with a plurality of first slots (110), and the additional sections being formed with a plurality of additional slots. The conductor bar (21) comprises a conductor bar middle section (211) formed in the first slot (110) and a conductor bar large end formed in the additional slot, On a projection plane perpendicular to the axial direction, the profile of the large end of the conductor bar is larger than the profile of the middle section (211) of the conductor bar.

2. The squirrel cage rotor according to claim 1, characterized in that: The additional section comprises a second section (12), wherein the second section (12) is formed with a plurality of second slots (120), and on a projection plane perpendicular to the axial direction, the second slots (120) extend beyond the first slots (110) on the radial inner side of the iron core (10).

3. The squirrel cage rotor according to claim 2, characterized in that: On a projection plane perpendicular to the axial direction, the second groove (120) also exceeds the first groove (110) on both sides in the circumferential direction.

4. The squirrel cage rotor according to claim 2, characterized in that: The additional section further comprises a reinforcing sheet (13), wherein the reinforcing sheet (13) is located on a side of the second section (12) facing away from the first section (11). The reinforcing sheet (13) is formed with a plurality of openings (130), and on a projection plane perpendicular to the axial direction, the outline of each of the openings (130) covers the outlines of the plurality of second grooves (120).

5. The squirrel cage rotor according to claim 1, characterized in that: The additional section is a reinforcement sheet (13), and the reinforcement sheet (13) is formed with a plurality of openings (130). On a projection plane perpendicular to the axial direction, the outline of each opening (130) covers the outlines of a plurality of the first grooves (110).

6. The squirrel cage rotor according to claim 5, characterized in that: In a projection perpendicular to the axial direction, the opening (130) extends beyond the first slot (110) on the radial inner side of the iron core (10).

7. The squirrel cage rotor according to any one of claims 4 to 6, characterized in that: The yield strength of the material from which the reinforcing sheet (13) is made is greater than the yield strength of the material from which the first section (11) is made.

8. The squirrel cage rotor according to any one of claims 1 to 3, characterized in that: On a cross section perpendicular to the axial direction, the contour of the additional section forms a concave-convex uneven structure on both sides of the circumferential direction, so that the large end of the guide bar forms a concave-convex structure in the circumferential direction.

9. The squirrel cage rotor according to any one of claims 1 to 3, characterized in that: The outer peripheral portion of the end ring (22) forms a slope surface (220).

10. The squirrel cage rotor according to any one of claims 1 to 3, characterized in that: The casting material of the squirrel cage (20) is pure aluminum.

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