Motor rotor, motor and electric equipment
By using plastic strips and U-shaped grooves in the motor rotor, the problems of insufficient mechanical strength and limited magnetic leakage effects caused by thin silicon steel sheets in high-speed permanent magnet motors are solved, and better magnetic leakage reduction is achieved and structural stability.
Patent Information
- Application Number
- CN202323397584.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-12
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2033-12-12
AI Technical Summary
In existing high-speed permanent magnet motors, in order to reduce magnetic leakage, thin silicon steel sheets are usually required to use as magnetic isolation bridges, but thin silicon steel sheets lead to insufficient mechanical strength of the motor and limited effect of reducing magnetic leakage.
By providing splicing first and second splicing blocks that can be spliced and fitted at the core splicing of the motor rotor, and opening a first glue injection groove and a first clamping groove at the splicing, the magnetic leakage is reduced by using a plastic rubber strip, and the magnetic leakage is reduced by The design of U-shaped groove improves splicing convenience and stability.
It effectively reduces magnetic leakage, improves the overall structural stability and mechanical strength of the motor rotor, and at the same time improves the power density and structural strength of the motor.
Smart Images
Figure CN222191941U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of motor manufacturing, and in particular to a motor rotor, a motor and an electrical device. Background Art
[0002] In the prior art, for high-speed permanent magnet motors, such as drive motors for new energy vehicles, in order to reduce magnetic flux leakage and pursue higher motor power density, it is usually necessary to set a magnetic isolation bridge at the core joint in the motor rotor. The existing magnetic isolation bridges are usually made of silicon steel sheets. In order to effectively reduce magnetic flux leakage, it is necessary to reduce the thickness of the silicon steel sheets as much as possible. However, if the thickness of the silicon steel sheets is too small, there is a problem of poor mechanical strength of the corresponding motor. At present, the minimum thickness of the silicon steel sheets is only about 0.5 mm, and the effect of reducing magnetic flux leakage is relatively limited. Utility Model Content
[0003] The purpose of the present application is to provide a motor rotor, a motor and an electrical device, which have the advantage of better reducing magnetic leakage. At the same time, the corresponding motor rotor also has the advantages of relatively stable overall structure and high mechanical strength.
[0004] The embodiment of the present application is implemented as follows:
[0005] In the first aspect, an embodiment of the present application provides a motor rotor, comprising a plurality of iron core monomers, which are spliced in sequence to form the motor rotor. Along the radial direction of the motor rotor, each iron core monomer comprises a first splicing block and a second splicing block that can be spliced together. A first glue injection groove is provided at the edge of the joint of the first splicing block, and the first glue injection groove corresponds to the magnetic steel groove in the first splicing block. A first clamping groove is provided on the bottom wall of the first glue injection groove. A first boss that can be clamped together with the first clamping groove is provided at the joint of the second splicing block. When the first boss is clamped in the first clamping groove, a glue injection area is formed between the side of the first boss and the first glue injection groove.
[0006] In the above technical solution, a first glue injection groove is provided at the joint of the iron core in the motor rotor, and the leakage magnetic field is reduced by injecting glue in the first glue injection groove to form a plastic strip. Since the plastic strip is not magnetically conductive, it has the advantage of better effect in reducing magnetic leakage compared with the method of setting silicon steel sheets to reduce the leakage magnetic field. In addition, a first clamping groove is provided in the first glue injection groove, and a first boss that can be clamped and matched with the first clamping groove is provided at the joint of the second splicing block. Through the clamping fit of the two, the convenience and accuracy of splicing the first splicing block and the second splicing block can be improved. At the same time, the stability and mechanical strength of the overall structure of the corresponding motor rotor can be improved after the injection of glue.
[0007] In some optional embodiments, the first clamping groove is a U-shaped groove and is recessed in a depth direction of the first glue injection groove.
[0008] In the above technical solution, the first snap-in groove is set in the form of a U-shaped groove. Since the corners in the groove are all in the form of arc transition, when the first boss and the first snap-in groove are snap-fitted, the risk of damage between the two due to scratching each other can be effectively reduced, thereby extending the service life of the corresponding components; in addition, the U-shaped groove is set in the form of a recessed form in the depth direction of the first glue injection groove, which also has the advantage of being easy to snap-in.
[0009] In some optional embodiments, the first clamping groove is located at an end of the first glue injection groove close to the second splicing block.
[0010] In the above technical solution, the first clamping groove is opened at the above specific position, which not only facilitates the clamping, but also forms a larger glue injection area after the clamping, thereby better reducing magnetic leakage.
[0011] In some optional implementation schemes, in the circumferential direction of the motor rotor, the ratio of the inner width of the first clamping groove to the inner width of the first glue injection groove is 1:5 to 1:7.
[0012] In the above technical solution, on the circumferential direction of the motor rotor, the ratio of the inner width of the first clamping groove and the first glue injection groove is limited to a specific range, which can better take into account the overall structural stability of the corresponding motor rotor and effectively reduce magnetic leakage (if the inner width of the first clamping groove is too small, the stability after clamping is poor; if the inner width of the first clamping groove is too large, the size of the glue strip formed after glue injection is small, and the effect of reducing magnetic leakage is poor).
[0013] In some optional embodiments, in the radial direction of the motor rotor, the inner width of the first glue injection groove gradually decreases from a side close to the magnetic steel slot to a side away from the magnetic steel slot.
[0014] In the above technical solution, the first glue injection groove is set to a special form of being larger inside and smaller outside. After the glue strip is formed by glue injection, the glue strip can be stably clamped in the first glue injection groove, thereby effectively reducing the risk of the glue strip falling off during operation, so as to improve the stability of the overall structure of the motor rotor.
[0015] In some optional embodiments, in the circumferential direction of the motor rotor, the inner width of the first glue injection groove is not less than the size of the magnetic steel groove in the corresponding area.
[0016] In the above technical solution, in the circumferential direction of the motor rotor, the inner width of the first glue injection groove is set to a special form that is not less than the size of the magnetic steel groove in the corresponding area, which can basically achieve full coverage of the corresponding area of the magnetic steel groove to better reduce magnetic leakage.
[0017] In some optional embodiments, in the radial direction of the motor rotor, the distance from the opening of the first glue injection groove to the bottom wall of the first glue injection groove is L1, the distance from the bottom wall of the first glue injection groove to the bottom wall of the corresponding magnetic steel groove is L2, and the ratio of L1 to L2 is 1:1 to 1:1.5.
[0018] In the above technical solution, the radial opening position and size of the first glue injection groove are limited to a specific range, so that a glue strip with a suitable thickness can be formed at a specific position, thereby better reducing magnetic leakage.
[0019] In some optional embodiments, the second splicing block includes a main splicing piece and a secondary splicing piece that can be spliced together. The main splicing piece can be spliced together with the first splicing block. A first boss is provided at the joint where the main splicing piece and the first splicing block are spliced together, and a second glue injection groove is provided at the edge of the joint where the main splicing piece and the secondary splicing piece are spliced together. The second glue injection groove corresponds to the magnetic steel groove in the main splicing piece. When the main splicing piece and the secondary splicing piece are spliced together, a glue injection area is formed between the side of the secondary splicing piece and the second glue injection groove.
[0020] In the above technical solution, the second splicing block is arranged in a form in which the main splicing piece and the auxiliary splicing piece can be spliced and matched, and a second glue injection groove corresponding to the magnetic steel groove inside the main splicing piece is opened on the edge of the main splicing piece (so as to reduce leakage magnetic flux by injecting glue in the second glue injection groove to form a plastic glue strip). Compared with the second splicing block of the conventional structure (the second splicing block is usually arranged as an integral whole, and the area corresponding to the magnetic steel groove in the second splicing block is not specially provided with a magnetic isolation bridge, and accordingly, there is also a more serious magnetic leakage problem), it has the advantage of better effect in reducing magnetic leakage.
[0021] In a second aspect, an embodiment of the present application provides a motor, comprising a motor rotor as provided in the embodiment of the first aspect.
[0022] In the above technical solution, the motor includes a motor rotor as provided in the first aspect embodiment, and the motor rotor has the advantages of better reducing magnetic leakage, relatively stable overall structure and high mechanical strength, so that the motor has higher power density and higher structural strength.
[0023] In a third aspect, an embodiment of the present application provides an electrical device, including a motor provided in the embodiment of the second aspect.
[0024] In the above technical solution, the electrical equipment includes a motor as provided in the embodiment of the second aspect. By taking advantage of the motor's high power density, sufficient power can be provided for the electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0026] Figure 1 A schematic diagram of the structure of a motor rotor provided in an embodiment of the present application;
[0027] Figure 2 A schematic diagram of the structure of an iron core monomer after assembly provided in an embodiment of the present application;
[0028] Figure 3 A schematic diagram of the structure of a core unit after being disassembled provided in an embodiment of the present application;
[0029] Figure 4 for Figure 3 A partial enlarged view of the middle A;
[0030] Figure 5 A schematic diagram of the structure of a second splicing block after assembly provided in an embodiment of the present application;
[0031] Figure 6 A schematic diagram of the structure of a second splicing block after being disassembled provided in an embodiment of the present application;
[0032] Figure 7 for Figure 6 A partial enlarged view of point B in the middle.
[0033] Icon: 10-motor rotor; 100-core monomer; 110-first splicing block; 111-first glue injection groove; 112-first clamping groove; 120-second splicing block; 121-main splicing piece; 1211-first boss; 1212-second glue injection groove; 1213-second clamping groove; 122-secondary splicing piece; 1221-second boss; 130-magnetic steel groove. DETAILED DESCRIPTION
[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.
[0035] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.
[0036] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.
[0037] In the description of this application, it should be noted that the terms "upper", "lower", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish descriptions, and cannot be understood as indicating or implying relative importance.
[0038] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0039] The motor rotor, motor and electrical equipment provided in this application are described in detail below.
[0040] See also Figure 1 to Figure 4 In a first aspect, an embodiment of the present application provides a motor rotor 10, comprising a plurality of core monomers 100, which are sequentially spliced to form the motor rotor 10. Along the radial direction of the motor rotor 10, each core monomer 100 comprises a first splicing block 110 and a second splicing block 120 that can be spliced together. A first glue injection groove 111 is provided at the edge of the splicing portion of the first splicing block 110. The first glue injection groove 111 corresponds to the magnetic steel groove 130 in the first splicing block 110. A first clamping groove 112 is provided on the bottom wall of the first glue injection groove 111. A first boss 1211 that can be clamped together with the first clamping groove 112 is provided at the splicing portion of the second splicing block 120. When the first boss 1211 is clamped in the first clamping groove 112, a glue injection area is formed between the side of the first boss 1211 and the first glue injection groove 111.
[0041] It should be noted that the opening position of the first glue injection groove 111 corresponds to the edge of the magnetic steel groove 130 in the first splicing block 110, that is, corresponds to the position of the existing magnetic isolation bridge, that is, the installation position of the silicon steel sheet for reducing magnetic leakage.
[0042] In the present application, a first glue injection groove 111 is provided at the core joint of the motor rotor 10, and the leakage magnetic field is reduced by injecting glue in the first glue injection groove 111 to form a plastic strip. Since the plastic strip is not magnetically conductive, it has the advantage of better reducing the magnetic leakage effect compared to the method of setting a silicon steel sheet to reduce the leakage magnetic field. In addition, a first clamping groove 112 is provided in the first glue injection groove 111, and a first boss 1211 that can be clamped and matched with the first clamping groove 112 is provided at the joint of the second splicing block 120. Through the clamping fit of the two, the convenience and accuracy of splicing the first splicing block 110 and the second splicing block 120 can be improved. At the same time, the stability and mechanical strength of the corresponding overall structure of the motor rotor 10 can be improved after the injection of glue.
[0043] It is understandable that the specific configuration of the first snap-fitting groove 112 is not limited and can be set according to conventional selections in the art as long as the snap-fitting and fixing function can be achieved.
[0044] See also Figure 4 As an example, the first clamping groove 112 is a U-shaped groove and is recessed in the depth direction of the first glue injection groove 111 .
[0045] In this embodiment, the first snap-in groove 112 is configured as a U-shaped groove. Since the corners in the groove are in the form of arc transitions, when the first boss 1211 and the first snap-in groove 112 are snap-fitted, the risk of damage due to mutual scratching can be effectively reduced, thereby extending the service life of the corresponding components. In addition, the U-shaped groove is configured to be concave in the depth direction of the first glue injection groove 111, which also has the advantage of being easy to snap-in.
[0046] In other possible implementations, the U-shaped groove may also be recessed in other directions as long as it can be snap-fitted with the first protrusion 1211 .
[0047] As an example, the first engaging groove 112 is located at an end of the first glue injection groove 111 close to the second assembling block 120 .
[0048] In this embodiment, the first clamping groove 112 is opened at the above-mentioned specific position, which not only facilitates the clamping, but also forms a larger glue injection area after the clamping, thereby better reducing magnetic leakage.
[0049] As an example, in the circumferential direction of the motor rotor 10, the ratio of the inner width of the first clamping groove 112 to the inner width of the first glue injection groove 111 is 1:5 to 1:7, for example but not limited to, the ratio of the inner widths of the two is any point value of 1:5, 1:6 and 1:7 or a range value between any two.
[0050] In this embodiment, on the circumference of the motor rotor 10, the ratio of the inner width of the first clamping groove 112 and the first glue injection groove 111 is limited to a specific range, which can better take into account the overall structural stability of the corresponding motor rotor 10 and effectively reduce magnetic leakage (if the inner width of the first clamping groove 112 is too small, the stability after clamping is poor; if the inner width of the first clamping groove 112 is too large, the size of the glue strip formed after glue injection is small, and the effect of reducing magnetic leakage is poor).
[0051] See also Figure 4 As an example, in the radial direction of the motor rotor 10 , the inner width of the first glue injection groove 111 gradually decreases from a side close to the magnetic steel groove 130 to a side away from the magnetic steel groove 130 .
[0052] In this embodiment, the first glue injection groove 111 is set to a special form of being larger inside and smaller outside. After the glue strip is formed by glue injection, the glue strip can be stably clamped in the first glue injection groove 111, thereby effectively reducing the risk of the glue strip falling off during operation, thereby improving the stability of the overall structure of the motor rotor 10.
[0053] In other possible implementations, in the radial direction of the motor rotor 10 , the inner width of the first glue injection groove 111 may be gradually increased from the side close to the magnetic steel groove 130 to the side away from the magnetic steel groove 130 , or may be the same everywhere.
[0054] See also Figure 4 As an example, in the circumferential direction of the motor rotor 10 , the first glue injection groove 111 is located in the middle of the magnetic steel groove 130 in the corresponding area.
[0055] In this embodiment, on the circumference of the motor rotor 10, the first glue injection groove 111 is set in the middle of the magnetic steel slot 130 in the corresponding area, which can more effectively reduce magnetic leakage (the closer to the middle of the magnetic steel slot 130, the stronger the magnetic field in the corresponding area, so setting the glue strip at this specific position can more effectively reduce magnetic leakage).
[0056] In other possible implementations, in the circumferential direction of the motor rotor 10 , the first glue injection groove 111 may also be in the form of one side edge close to the magnetic steel groove 130 in the corresponding area.
[0057] As an example, in the circumferential direction of the motor rotor 10 , the inner width of the first glue injection groove 111 is not less than the size of the magnetic steel groove 130 in the corresponding area.
[0058] In this embodiment, in the circumferential direction of the motor rotor 10, the inner width of the first glue injection groove 111 is set to a special form that is not less than the size of the magnetic steel groove 130 in the corresponding area, which can basically achieve full coverage of the corresponding area of the magnetic steel groove 130 to better reduce magnetic leakage.
[0059] It is understandable that the position and thickness of the glue strip formed after glue injection are closely related to the effect of reducing magnetic leakage. Based on this, the opening position and size of the first glue injection groove 111 in the radial direction of the motor rotor 10 can be adjusted.
[0060] As an example, in the radial direction of the motor rotor 10, the distance from the opening of the first glue injection groove 111 to the bottom wall of the first glue injection groove 111 is L1 (that is, the depth of the first glue injection groove 111 is L1), and the distance from the bottom wall of the first glue injection groove 111 to the bottom wall of the corresponding magnetic steel groove 130 is L2, and the ratio of L1 to L2 is 1:1 to 1:1.5, for example but not limited to, the ratio of the two is any one of 1:1.1, 1:1.2, 1:1.3, 1:1.4 and 1:1.5 or a range value between any two.
[0061] In this embodiment, the radial opening position and size of the first glue injection groove 111 are limited to a specific range, so that a glue strip with a suitable thickness can be formed at a specific position, thereby better reducing magnetic leakage.
[0062] See also Figure 5 to Figure 7 As an example, the second splicing block 120 includes a main splicing piece 121 and a secondary splicing piece 122 that can be spliced and matched. The main splicing piece 121 can be spliced and matched with the first splicing block 110. A first boss 1211 is provided at the splicing point where the main splicing piece 121 and the first splicing block 110 are spliced and matched, and a second glue injection groove 1212 is provided at the edge of the splicing point where the main splicing piece 121 and the secondary splicing piece 122 are spliced and matched. The second glue injection groove 1212 corresponds to the magnetic steel groove 130 in the main splicing piece 121. When the main splicing piece 121 and the secondary splicing piece 122 are spliced and matched, a glue injection area is formed between the side of the secondary splicing piece 122 and the second glue injection groove 1212.
[0063] In this embodiment, the second splicing block 120 is configured in a form in which the main splicing piece 121 and the auxiliary splicing piece 122 can be spliced and matched, and a second glue injection groove 1212 corresponding to the magnetic steel groove 130 inside the main splicing piece 121 is opened on the edge of the main splicing piece 121 (so as to reduce leakage magnetic flux by injecting glue in the second glue injection groove 1212 to form a plastic glue strip). Compared with the second splicing block 120 of a conventional structure (the second splicing block 120 is usually arranged as an integral whole, and the area corresponding to the magnetic steel groove 130 in the second splicing block 120 is not specially provided with a magnetic isolation bridge, and accordingly, there is also a more serious magnetic leakage problem), it has the advantage of better effect in reducing magnetic leakage.
[0064] See also Figure 7 As an example, along the radial direction of the motor rotor 10, a second clamping groove 1213 is provided on the bottom wall of the second glue injection groove 1212, and a second boss 1221 capable of being clamped and matched with the second clamping groove 1213 is provided at the joint of the auxiliary splicing piece 122. When the second boss 1221 is clamped in the second clamping groove 1213, a glue injection area is formed between the side of the second boss 1221 and the second glue injection groove 1212.
[0065] In this embodiment, a second snap-in groove 1213 is opened in the second glue injection groove 1212, and a second boss 1221 that can snap-fit with the second snap-in groove 1213 is provided at the joint of the secondary splicing piece 122. Through the snap-fitting of the two, the convenience and accuracy of splicing the main splicing piece 121 and the secondary splicing piece 122 can be improved. At the same time, the stability and mechanical strength of the overall structure of the corresponding motor rotor 10 can be improved after glue injection.
[0066] It should be noted that there is no limitation on the structures or components not specifically described in the motor rotor 10 , and they can be arranged according to conventional selections in the art.
[0067] In a second aspect, an embodiment of the present application provides a motor, comprising a motor rotor 10 provided in the embodiment of the first aspect.
[0068] In the present application, the motor includes a motor rotor 10 as provided in the first aspect embodiment. The motor rotor 10 has the advantages of better reducing magnetic leakage, relatively stable overall structure and high mechanical strength, so that the motor has higher power density and higher structural strength.
[0069] In a third aspect, an embodiment of the present application provides an electrical device, including a motor provided in the embodiment of the second aspect.
[0070] In the present application, the electrical equipment includes a motor as provided in the second aspect embodiment. By taking advantage of the motor's high power density, sufficient power can be provided for the electrical equipment.
[0071] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A motor rotor, characterized in that: It comprises a plurality of core monomers, which are sequentially spliced to form the motor rotor. Along the radial direction of the motor rotor, each of the core monomers comprises a first splicing block and a second splicing block which can be spliced together. A first glue injection groove is provided at the edge of the splicing part of the first splicing block, and the first glue injection groove corresponds to the magnetic steel groove in the first splicing block. A first clamping groove is provided on the bottom wall of the first glue injection groove. A first boss which can be clamped together with the first clamping groove is provided at the splicing part of the second splicing block. When the first boss is clamped in the first clamping groove, a glue injection area is formed between the side of the first boss and the first glue injection groove.
2. The motor rotor according to claim 1, characterized in that: The first clamping groove is a U-shaped groove and is recessed in a depth direction of the first glue injection groove.
3. The motor rotor according to claim 2, characterized in that: The first clamping groove is located at an end of the first glue injection groove close to the second splicing block.
4. The motor rotor according to claim 3, characterized in that: In the circumferential direction of the motor rotor, the ratio of the inner width of the first clamping groove to the inner width of the first glue injection groove is 1:5 to 1:
7.
5. The motor rotor according to any one of claims 1 to 4, characterized in that: In the radial direction of the motor rotor, the inner width of the first glue injection groove gradually decreases from a side close to the magnetic steel groove to a side far away from the magnetic steel groove.
6. The motor rotor according to any one of claims 1 to 4, characterized in that: In the circumferential direction of the motor rotor, the inner width of the first glue injection groove is not less than the size of the magnetic steel groove in the corresponding area.
7. The motor rotor according to any one of claims 1 to 4, characterized in that: In the radial direction of the motor rotor, the distance from the opening of the first glue injection groove to the bottom wall of the first glue injection groove is L1, and the distance from the bottom wall of the first glue injection groove to the bottom wall of the corresponding magnetic steel groove is L2, and the ratio of L1 to L2 is 1:1 to 1:1.
5.
8. The motor rotor according to any one of claims 1 to 4, characterized in that: The second splicing block includes a main splicing piece and an auxiliary splicing piece that can be spliced and matched. The main splicing piece can be spliced and matched with the first splicing block. The first boss is provided at the splicing point where the main splicing piece and the first splicing block are spliced and matched, and a second glue injection groove is provided at the edge of the splicing point where the main splicing piece and the auxiliary splicing piece are spliced and matched. The second glue injection groove corresponds to the magnetic steel groove in the main splicing piece. When the main splicing piece and the auxiliary splicing piece are spliced and matched, a glue injection area is formed between the side of the auxiliary splicing piece and the second glue injection groove.
9. A motor, characterized in that: The invention comprises a motor rotor as claimed in any one of claims 1 to 8.
10. An electrical device, characterized in that: Comprising the motor as claimed in claim 9.