Electric machine with permanent magnet rotor
By fixing permanent magnets to the magnetic core using fixed blades in a 'V' shaped arrangement and alternating laminations, the electric machine addresses manufacturing cost and imbalance issues, achieving a balanced and cost-effective rotor design.
Patent Information
- Application Number
- JP2025124231
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-08-01
- Filing Date
- 2025-07-24
- Publication Date
- 2026-02-16
AI Technical Summary
Existing electric machines with permanent magnet rotors face issues such as increased manufacturing costs, weight, and rotor imbalance due to the use of adhesives to fix permanent magnets, which can disperse irregularly during high-speed rotation.
The permanent magnets are firmly fixed to the magnetic core using fixed blades without adhesives, with a 'V' shaped arrangement and alternating laminations to ensure secure attachment and balanced distribution.
This method reduces manufacturing costs and improves rotor balance, ensuring a cost-effective and balanced rotor structure without the drawbacks of adhesive use.
Smart Images
Figure 2026025958000001_ABST
Abstract
Description
[Technical Field]
[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to Italian Patent Application No. 102024000018064, filed August 1, 2024, the entire disclosure of which is incorporated herein by reference.
[0002] The present invention relates to electric machines having permanent magnet rotors. [Background technology]
[0003] EP 4243249 A1 describes a synchronous electric machine with a rotor having permanent magnets (i.e., arranged inside the rotor), which is primarily used in the automotive industry. In this electric machine, the rotor includes a magnetic core consisting of a series of stacked laminations and a plurality of permanent magnets embedded inside the magnetic core. In particular, the magnetic core includes a series of axially arranged sheets into which the permanent magnets are inserted. To ensure that the permanent magnets remain stationary inside the sheets even when subjected to stresses resulting from the rotor's rotation at high speeds (which can reach 30,000 rpm), the permanent magnets are connected to the inner walls of the sheets with adhesive. However, gluing the permanent magnets inside the sheets increases manufacturing costs, slightly increases weight, and can increase rotor imbalance (because the adhesive, subjected to the thrust of the permanent magnets when inserted axially, can often disperse itself irregularly within the sheets). That is, fixing the permanent magnets by applying adhesive can result in imbalances inside the rotor, since it is very difficult to obtain a uniform distribution of the adhesive inside the sheet.
[0004] Other examples of synchronous electric machines with permanent magnet rotors are described in US Patent Application Publication No. 2008007131 and WO2006003244.
[0005] French patent application FR 3 129 792 describes a rotor for a rotating electrical machine, comprising, in a cross section perpendicular to the rotor's axis of rotation, permanent magnets having long and short sides, and a magnetic core provided with a number of axially oriented sheets made of a series of laminations stacked on top of one another and housing the permanent magnets, in each sheet at least one lamination having at least one tab extending into the sheet to reach into contact with the respective permanent magnet and pressing the permanent magnet against the opposite face of the sheet.
[0006] Chinese Patent No. 115378204 describes a method for manufacturing a laminated magnetic core for a rotor of a rotating electrical machine. Summary of the Invention
[0007] SUMMARY OF THE INVENTION It is an object of the present invention to provide an electric machine with a permanent magnet rotor which does not suffer from the above-mentioned drawbacks and which at the same time is easy and cost-effective to manufacture.
[0008] According to the present invention there is provided an electric machine having a permanent magnet rotor as claimed in the accompanying claims.
[0009] The claims describe preferred embodiments of the invention and form an integral part of this specification. [Brief explanation of the drawings]
[0010] The present invention will now be described with reference to the accompanying drawings, which show some non-limiting exemplary embodiments thereof. [Figure 1] 1 is a schematic longitudinal cross-sectional view, with parts removed for clarity, of an electric machine having a permanent magnet rotor constructed in accordance with the present invention; [Figure 2] FIG. 2 is a partially exploded perspective view, with parts removed for clarity, of a rotor magnetic core of the electric machine of FIG. 1; [Figure 3] 2 is a plan view of a first type of lamination that makes up the rotor magnetic core of the electric machine of FIG. 1; FIG. [Figure 4]4A and 4B are enlarged views of a sheet of the laminate of FIG. 3 without and with a corresponding permanent magnet, respectively. [Figure 5] 4A and 4B are enlarged views of a sheet of the laminate of FIG. 3 without and with a corresponding permanent magnet, respectively. [Figure 6] 4A and 4B are enlarged views of a sheet of the stack of FIG. 3 without a corresponding permanent magnet and a further sheet of the stack of FIG. 3 with a corresponding permanent magnet, respectively. [Figure 7] 4A and 4B are enlarged views of a sheet of the stack of FIG. 3 without a corresponding permanent magnet and a further sheet of the stack of FIG. 3 with a corresponding permanent magnet, respectively. [Figure 8] 2 is a plan view of a second type of lamination that makes up the rotor magnetic core of the electric machine of FIG. 1; FIG. [Figure 9] 9A and 9B are enlarged views of a sheet of the laminate of FIG. 8 without and with a corresponding permanent magnet, respectively. [Figure 10] 9A and 9B are enlarged views of a sheet of the laminate of FIG. 8 without and with a corresponding permanent magnet, respectively. [Figure 11] 9A and 9B are enlarged views of a sheet of the stack of FIG. 8 without a corresponding permanent magnet and a further sheet of the stack of FIG. 8 with a corresponding permanent magnet, respectively. [Figure 12] 9A and 9B are enlarged views of a sheet of the stack of FIG. 8 without a corresponding permanent magnet and a further sheet of the stack of FIG. 8 with a corresponding permanent magnet, respectively. [Figure 13] 1A and 1B are schematic views of respective details of the rotor magnetic core of the electric machine of FIG. 1, in particular FIG. 13 is a cross-sectional view along line XIII-XIII and FIG. 14 is a cross-sectional view along line XIV-XIV. [Figure 14] 1A and 1B are schematic views of respective details of the rotor magnetic core of the electric machine of FIG. 1, in particular FIG. 13 is a cross-sectional view along line XIII-XIII and FIG. 14 is a cross-sectional view along line XIV-XIV. [Figure 15] 1A and 1B are schematic views of respective details of the rotor magnetic core of the electric machine of FIG. 1, in particular FIG. 13 is a cross-sectional view along line XIII-XIII and FIG. 14 is a cross-sectional view along line XIV-XIV. [Figure 16] 1A and 1B are schematic views of respective details of the rotor magnetic core of the electric machine of FIG. 1, in particular FIG. 13 is a cross-sectional view along line XIII-XIII and FIG. 14 is a cross-sectional view along line XIV-XIV. DETAILED DESCRIPTION OF THE INVENTION
[0011] 1, reference numeral 1 generally designates a synchronous electric machine for the automotive industry of reversible type (i.e., capable of operating both as an electric motor, absorbing electrical energy to generate mechanical torque, and as a generator, absorbing mechanical energy to generate electrical energy). Electric machine 1 comprises a shaft 2 mounted for rotation about a central rotation axis 3, a permanent magnet rotor 4 having a cylindrical shape and keyed to shaft 2 for rotation therewith, and a stator 5 having a cylindrical tubular shape arranged around rotor 4 to surround it.
[0012] According to what is shown in FIG. 2, the rotor 4 comprises a magnetic core 6 and a plurality of magnetic poles 7 made of permanent magnets 8 and 9 embedded inside the magnetic core 6 .
[0013] 2, each magnetic pole 7 comprises two permanent magnets 8, which are arranged adjacent to each other at a fixed distance from each other in respective seats 10 (better visible in FIGS. 3 and 8) obtained axially inside the magnetic core 6. According to a preferred embodiment, in each magnetic pole 7, the two permanent magnets 8 are arranged inclined relative to each other so that they form a "V" shape (with an obtuse angle at the apex), i.e., in each magnetic pole 7, the two permanent magnets 8 are arranged adjacent to each other and inclined to form an obtuse angle in each pair of seats 10 spaced apart from each other, so that between the two seats 10, the magnetic core 6 is radially oriented and has a bridge spanning the two permanent magnets 8. Furthermore, each magnetic pole 7 comprises two permanent magnets 9, which are arranged adjacent to each other at a fixed distance from each other in respective seats 11 (better visible in FIGS. 3 and 8) obtained axially inside the magnetic core 6. According to a preferred embodiment, in each magnetic pole 7, the two permanent magnets 9 are arranged inclined relative to each other so that the two permanent magnets 9 form a "V" shape (with an obtuse angle at the apex), i.e., in each magnetic pole 7, the two permanent magnets 9 are arranged adjacent to each other and inclined to form an obtuse angle at each pair of sheets 11 spaced apart from each other, so that between the two sheets 11, the magnetic core 6 is radially oriented and has a bridge spanning the two permanent magnets 9. In particular, in each magnetic pole 7, the two permanent magnets 9 are smaller than the two permanent magnets 8 and are arranged radially outside the two permanent magnets 8, in the area defined by the two permanent magnets 8.
[0014] It is important to recall that an obtuse angle is a convex angle whose width is greater than 90° (corresponding to a right angle) and less than 180° (corresponding to a flat angle); in other words, an obtuse angle is greater than a right angle (i.e., greater than 90°) and less than a flat angle (i.e., less than 180°).
[0015] According to a preferred embodiment shown in the accompanying drawings, in each magnetic pole 7, the obtuse angle formed between the two permanent magnets 8 is smaller than the obtuse angle formed between the two permanent magnets 9. In particular, in each magnetic pole 7, the obtuse angle formed between the two permanent magnets 8 is equal to 110° and the obtuse angle formed between the two permanent magnets 9 is equal to 120°.
[0016] According to the preferred embodiment shown in the accompanying drawings, in each magnetic pole 7, the first distance existing between the proximal ends (i.e., the two ends closest to each other) of the two permanent magnets 8 is greater than the second distance existing between the proximal ends (i.e., the two ends closest to each other) of the two permanent magnets 9. Similarly, in each magnetic pole 7, the third distance existing between the proximal ends (i.e., the two ends closest to each other) of the two sheets 10 is greater than the fourth distance existing between the proximal ends (i.e., the two ends closest to each other) of the two sheets 11.
[0017] Each permanent magnet 8 or 9 has a parallelepiped shape whose exterior is defined by two larger side walls that are parallel to and opposite each other and two smaller side walls that are parallel to and opposite each other and perpendicular to the larger side walls, the two larger side walls obviously having a larger extent (area) than the two smaller side walls.
[0018] The magnetic core 6 consists of a series of laminations 12 and 13 (different from one another as will be explained below) stacked on top of one another and has a plurality of spaced apart axial sheets 10 and 11 in which the permanent magnets 8 and 9 are inserted (as mentioned above). In particular, the laminations 12 are alternated with the laminations 13 (different from the laminations 12 as will be explained below) so that at least 10 laminations 13 are interposed between two laminations 12, in particular at least 15, preferably at least 20 laminations 13 are interposed between two laminations 12 (according to a preferred embodiment, 20 to 30 laminations 13 are interposed between two laminations 12).
[0019] 4 and 5, each stack 12 has, for each sheet 10, only two fixed blades 14 that are parallel to each other, arranged on the same side of the sheet 10, and bent at 90° relative to the same larger sidewall of the corresponding permanent magnet 8 housed in the sheet 10 (according to a different embodiment not shown, each stack 12 has, for each sheet 10, at least two fixed blades 14, i.e., three or more fixed blades 14 can be provided for each sheet 10). Furthermore, each stack 12 has, for each sheet 10, one single fixed blade 15 that is oriented perpendicular to the corresponding fixed blade 14 and bent at 90° relative to the smaller sidewall of the corresponding permanent magnet 8 housed in the sheet 10 (according to a different embodiment not shown, each stack 12 has, for each sheet 10, two or more fixed blades 15).
[0020] According to another embodiment not shown, the number of fixed blades 14 in each sheet 10 is different, varying from a minimum of 2 to a maximum of 4 or 5. Similarly, according to another embodiment not shown, the number of fixed blades 15 in each sheet 10 is different, varying from a minimum of 1 to a maximum of 2 or 3. In general, the number of fixed blades 14 and 15 is established as a function of the dimensions (length and width) of the fixed blades 14 and 15, as a function of the dimensions (length and width) of each permanent magnet 8, and as a function of the desired holding force that the fixed blades 14 and 15 must exert on each permanent magnet 8.
[0021] According to a preferred embodiment, each sheet 10 has a flat wall 16 opposite two fixed blades 14, which press a corresponding permanent magnet 8 housed in the sheet 10 against the flat wall 16. That is, the corresponding permanent magnet 8 is stacked between the two fixed blades 14 and the flat wall 16 of the sheet 10 and is pressed against the flat wall 16 of the sheet 10 by the two fixed blades 14.
[0022] According to a preferred embodiment, each sheet 10 has teeth 17 that protrude into the sheet 10 and are oriented perpendicular to the wall 16, against which the fixed blade 15 presses the corresponding permanent magnet 8 housed in the sheet 10, i.e., the corresponding permanent magnet 8 is stacked between the fixed blade 15 and the teeth 17 of the sheet 10 and is pressed against the teeth 17 of the sheet 10 by the fixed blade 15.
[0023] 6 and 7, each stack 12 has, for each sheet 11, one single fixed blade 18 bent at 90° relative to the larger sidewall of the corresponding permanent magnet 9 housed in the second sheet 11, and furthermore, each stack 12 has, for each sheet 11, one single fixed blade 19 oriented perpendicular to the corresponding fixed blade 18 and bent at 90° relative to the smaller sidewall of the corresponding permanent magnet 9 housed in the sheet 11. According to another embodiment not shown, the number of fixed blades 18 in each sheet 11 is different, varying from a minimum of 1 to a maximum of 2 or 3. Similarly, according to another embodiment not shown, the number of fixed blades 19 in each sheet 11 is different, varying from a minimum of 1 to a maximum of 2 or 3. In general, the number of fixed blades 18 and 19 is established as a function of the dimensions (length and width) of the fixed blades 18 and 19, as a function of the dimensions (length and width) of each permanent magnet 9, and as a function of the desired holding force that the fixed blades 18 and 19 must exert on each permanent magnet 9.
[0024] According to a preferred embodiment, each sheet 11 has a flat wall 20 opposite a fixed blade 19, and the fixed blade 19 presses a corresponding permanent magnet 9 housed in the sheet 11 against the flat wall 20. That is, the corresponding permanent magnet 9 is stacked between the fixed blade 19 and the flat wall 20 of the sheet 11, and is pressed against the flat wall 20 of the sheet 11 by the fixed blade 19.
[0025] According to a preferred embodiment, each sheet 11 has teeth 21 that protrude into the sheet 11 and are oriented perpendicular to the wall 20, and the fixed blade 19 presses the corresponding permanent magnet 9 housed in the sheet 11 against the teeth 21, i.e., the corresponding permanent magnet 9 is stacked between the fixed blade 19 and the teeth 21 of the sheet 11 and is pressed against the teeth 21 of the sheet 11 by the fixed blade 19.
[0026] 8 to 11, unlike the lamination 12 having fixed blades 14 and 15, the lamination 13 is completely devoid of fixed blades bent relative to the permanent magnets 8 and 9. That is, the fixed blades 14-15 and 18-19 are not present in all laminations 12 or 13, but only in the lamination 12, so that, as shown in FIGS. 13 to 16, there is a certain axial distance (equal to the thickness of the lamination 13 interposed between two subsequent laminations 12) between the fixed blades 14-15 or 18-19 and the next fixed blade 14-15 or 18-19.
[0027] In general, the number of laminations 13 interposed between two laminations 12 is established as a function of the dimensions (length and width) of the fixed blades 14-15 and 18-19, as a function of the dimensions (length and width) of the permanent magnets 8 and 9, as a function of the number of permanent magnets 8 and 9 present inside the magnetic core 6, and as a function of the desired holding force that the fixed blades 14-15 and 18-19 must exert on the permanent magnets 8 and 9.
[0028] 13 to 15, in all the stacks 13, each sheet 10 has three recesses 22 (shown in FIGS. 9 and 10) that are arranged in the regions of the three fixed blades 14 and 15 of the stack 12 and form respective empty spaces for the bent portions of the fixed blades 14 and 15, and similarly, each sheet 11 has two recesses 23 (shown in FIGS. 11 and 12) that are arranged in the regions of the two fixed blades 18 and 19 of the stack 12 and form respective empty spaces for the bent portions of the fixed blades 18 and 19. In other words, all the stacks 13 are identical to one another, and therefore, in all the stacks 13, each sheet 10 has a recess 22 and each sheet 11 has a recess 23.
[0029] The space left by the recess 22 for the fixed blades 14 and 15 is shown diagrammatically in Figures 13 to 16, but the space left by the recess 23 for the fixed blade 18 is completely similar and therefore does not require further illustration (in addition to what is already shown in Figures 11 and 12).
[0030] 16, in only one group of laminates 13 arranged in contact with each laminate 12, each sheet 10 has three recesses 22 arranged in the region of the three fixed blades 14 and 15 of the laminate 12, forming respective empty spaces for the bent portions of the fixed blades 14 and 15, and each sheet 11 has two recesses 23 arranged in the region of the two fixed blades 18 and 19 of the laminate 12, forming respective empty spaces for the bent portions of the fixed blades 18 and 19, while the remaining laminates 13 instead lack the recesses 22 and 23. That is, in this embodiment, there are two types of laminates 13: a first type of laminate 13 in which each sheet 10 has a recess 22 and each sheet 11 has a recess 23, and a second type of laminate 13 in which no sheets 10 have a recess 22 and no sheets 11 have a recess 23. Groups of the first type laminations 13 (having recesses 22 and 23) are arranged in the regions of the zones engaged by the fixed blades 14-15 and 18-19 bent relative to the permanent magnets 8 and 9 (i.e., the zones where the fixed blades 14-15 and 18-19 bent relative to the permanent magnets 8 and 9 are arranged), while other groups of the second type laminations 13 (not having recesses 22 and 23) are arranged in the regions of the zones not engaged by the fixed blades 14-15 and 18-19 bent relative to the permanent magnets 8 and 9 (i.e., the zones where the fixed blades 14-15 and 18-19 bent relative to the permanent magnets 8 and 9 are not present). Thus, groups of the first type laminations 13 are arranged alternately with groups of the second type laminations 13 (as shown in FIG. 16).
[0031] The embodiments described herein can be combined with each other without departing from the scope of protection of the present invention.
[0032] The electric machine 1 described above has many advantages.
[0033] First, in the above-described electric machine 1, the permanent magnets 8 and 9 are firmly fixed to the respective sheets 10 and 11 without the use of adhesives, which results in a reduced manufacturing cost for the above-described electric machine 1 and a better balance for the rotor 4.
[0034] Furthermore, the above-described electric machine 1 is simple and cost-effective to manufacture since the fixed blades 14-15 and 18-19 can be easily obtained during shearing of the laminate 12 without any associated increase in manufacturing costs, and similarly the recesses 22 and 23 can be easily obtained during shearing of the laminate 13 without any associated increase in manufacturing costs.
[0035] List of drawing reference numbers 1 Electrical Machinery 2 shafts 3 Rotation Axis 4 rotors 5 Stator 6 magnetic core 7 magnetic poles 8. Permanent magnets 9. Permanent magnets 10 sheets 11 sheets 12 Laminate 13 Laminate 14 fixed blades 15 fixed blade 16 Wall 17 teeth 18 Fixed Blade 19 Fixed Blade 20 Wall 21 teeth 22 recess 23 Recess
Claims
1. An electric machine (1), a shaft (2) mounted for rotation about a central axis of rotation (3); a rotor (4) having a magnetic core (6) carried by the shaft (2) and consisting of a series of stacked laminations (12, 13) and having a plurality of axially oriented sheets (10, 11); and a plurality of magnetic poles (7), each comprising two first permanent magnets (8) arranged adjacent to each other and inclined to form a first obtuse angle in each pair of spaced-apart first sheets (10), and two second permanent magnets (9) arranged adjacent to each other and inclined to form a second obtuse angle in each pair of spaced-apart second sheets (11); a stator (5) disposed around the rotor (4) so as to surround the rotor (4); each of the first or second permanent magnets (8, 9) has a parallelepiped shape whose exterior is defined by two larger side walls that are parallel and opposite to each other and two smaller side walls that are parallel and opposite to each other and perpendicular to the larger side walls; In each magnetic pole (7), the two second permanent magnets (9) are smaller than the two first permanent magnets (8), are arranged radially outward of the two first permanent magnets (8), and are arranged in an area defined by the two first permanent magnets (8); The magnetic core (6) is configured by alternately arranging first laminations (12) and second laminations (13) different from the first laminations (12), and at least ten second laminations (13) are interposed between two first laminations (12); The electric machine (1) comprises: Each first stack (12) has at least two first fixed blades (14) that are parallel to each other, arranged on the same side of each first sheet (10), and bent at 90° relative to the same larger side wall of the corresponding first permanent magnet (8) housed in each first sheet (10); Each first stack (12) has, for each first sheet (10), at least one second fixed blade (15) that is oriented perpendicular to the corresponding first fixed blade (14) and bent at 90° to the smaller sidewall of the corresponding first permanent magnet (8) housed in the first sheet (10); Each first stack (12) has, for each second sheet (11), at least one third fixed blade (18) bent at 90° relative to the larger side wall of the corresponding second permanent magnet (9) housed in said second sheet (11); Each first stack (12) has, for each second sheet (11), at least one fourth fixed blade (19) that is oriented perpendicular to the corresponding third fixed blade (18) and bent 90° relative to the smaller sidewall of the corresponding second permanent magnet (9) housed in the second sheet (11); An electric machine (1), characterized in that each second lamination (13) is completely devoid of fixed blades bent relative to said first and second permanent magnets (8, 9).
2. 2. The electric machine (1) according to claim 1, wherein each first seat (10) has a flat wall (16) opposite the two first fixed blades (14), and the two first fixed blades (14) press the corresponding first permanent magnets (8) housed in the first seat (10) against the flat wall (16).
3. 3. The electric machine (1) according to claim 1 or 2, wherein each first seat (10) has a first tooth (17) that protrudes into the first seat, and the second fixed blade (15) presses the corresponding first permanent magnet (8) housed in the first seat (10) against the first tooth.
4. 4. An electric machine (1) according to claim 1, 2 or 3, wherein in each second laminate (13), each first sheet (10) has a first recess (22), the first recess (22) being arranged in the region of the fixed blade (14, 15) of the first laminate (12) and forming a respective free space for the bent portion of the fixed blade (14, 15).
5. a second laminate (13) of a first type is provided, each first sheet (10) having a first recess (22), the first recess (22) being arranged in the region of the first and second fixed blades (14, 15) of the first laminate (12) and forming respective free spaces for the bent portions of the first and second fixed blades (14, 15); a second laminate (13) of a second type is provided, each first sheet (10) being devoid of said first recesses (22); 4. The electric machine (1) according to claim 1, 2 or 3, wherein another group of the first type laminations (13) is arranged in a region of a zone where the first and second fixed blades (14, 15) of the first laminations (12) bent relative to the first permanent magnet (8) are arranged, and another group of the second type laminations (13) is arranged in a region of a zone where the first and second fixed blades (14, 15) of the first laminations (12) bent relative to the first permanent magnet (8) are not present.
6. 6. The electric machine (1) according to claim 1, wherein each second seat (11) has a flat wall (20) opposite the third fixed blade (18), and the third fixed blade (18) presses the corresponding second permanent magnet (9) housed in the second seat (11) against the flat wall (20).
7. 7. The electric machine (1) according to claim 1, wherein each second seat (11) has a second tooth (21), the second tooth (21) protruding into the second seat (11), and the fourth fixed blade (19) presses the corresponding second permanent magnet (9) housed in the second seat (11) against the second tooth (21).
8. 8. An electric machine (1) according to any one of claims 1 to 7, wherein in each second laminate (13), each second sheet (11) has a second recess (23) arranged in the region of the fixed blade (18, 19) of the first laminate (12) and forming a respective free space for the bent portion of the fixed blade (18, 19).
9. a second laminate (13) of a first type is provided, each second sheet (11) having second recesses (23) arranged in the region of the third and fourth fixed blades (18, 19) of the first laminate (12) and forming respective free spaces for the bent portions of the third and fourth fixed blades (18, 19); a second laminate (13) of a second type is provided, each second sheet (11) being devoid of said second recesses (23); 8. The electric machine (1) according to claim 1, wherein another group of laminations (13) of the first type is arranged in a region of a zone where the third and fourth fixed blades (18, 19) of the first laminations (12) bent relative to the second permanent magnet (9) are arranged, and another group of laminations (13) of the second type is arranged in a region of a zone where the third and fourth fixed blades (18, 19) of the first laminations (12) bent relative to the second permanent magnet (8) are not present.
10. Each first laminate (12) has two first fixed blades (14) and one single second fixed blade (15) for each first sheet (10); 10. An electric machine (1) according to any one of claims 1 to 9, wherein each first stack (12) has, for each second sheet (11), one single third fixed blade (18) and one single fourth fixed blade (19).
11. 11. Electric machine (1) according to any one of claims 1 to 10, wherein at least 15, preferably at least 20 second laminations (13) are interposed between two first laminations (12).
12. 12. An electric machine (1) according to any one of claims 1 to 11, wherein each magnetic pole (7) comprises exactly two, and only two, first permanent magnets (8) arranged adjacent to each other and inclined to form an obtuse angle, and exactly two, and only two, second permanent magnets (9) arranged adjacent to each other and inclined to form an obtuse angle.
13. 13. The electric machine (1) according to any one of claims 1 to 12, wherein in each magnetic pole (7), the first obtuse angle formed between two of the first permanent magnets (8) is smaller than the second obtuse angle formed between two of the second permanent magnets (9).
14. 14. The electric machine (1) according to any one of claims 1 to 13, wherein in each magnetic pole (7), the first obtuse angle formed between the two first permanent magnets (8) is equal to 110° and the second obtuse angle formed between the two second permanent magnets (9) is equal to 120°.
15. In each magnetic pole (7), a first distance between the proximal ends of the two first permanent magnets (8) is greater than a second distance between the proximal ends of the two second permanent magnets (9); 15. An electric machine (1) according to any one of claims 1 to 14, wherein in each magnetic pole (7), a third distance existing between the proximal ends of the two first sheets (10) is greater than a fourth distance existing between the proximal ends of the two second sheets (11).