Rotor for electric machine and axial-flow rotating electric machine

Abstract

The invention relates to a rotor (3) for an axial flow electric machine (1), comprising a disc (5) rotating together with an output shaft (4) and a plurality of permanent magnets (8) having the shape of a truncated disc sector; wherein at least one of the permanent magnets (8) is integrally formed and has a retaining portion (14) and a slotted portion (15) in a radial direction (R) of an axis X towards the outside, the permanent magnet (8) has a plurality of slots, all of which open on the slotted portion (15), and wherein the radial dimension of the retaining portion (14) is 10% to 30% of the radial dimension of the permanent magnet (8), and wherein the radial dimension of the permanent magnet (8) is 10% to 30% of the radial dimension of the permanent magnet (8). Wherein the plurality of slots comprises at least one radial slot (16) extending in a radial direction (R) and at least one orthogonal radial slot extending in an orthogonal radial direction (O).

Description

Technical Field

[0001] The present invention relates to the field of axial flow rotating motors, and more particularly to axial flow rotating motors for electric or hybrid vehicles. The present invention more specifically focuses on the rotors of these axial flow rotating motors. Background Art

[0002] Known axial flow rotating motors include permanent magnets in one or more rotors of the motor. These permanent magnets are exposed to the magnetic field generated by the coils of the stator, causing the rotor to rotate.

[0003] Permanent magnets for the automotive field are particularly large, and as a significant result, significant eddy currents are generated when using them. These eddy currents have an adverse effect on the performance of the system by generating heat at the magnets, and this may also damage the system.

[0004] To reduce eddy current losses, document WO2018172633 provides a method of using a large number of small magnets that are assembled together to form a permanent magnet. The assembly of this type of magnet is difficult and expensive, and it also takes a long time. In addition, after assembly, it is difficult to ensure the shape tolerance and position tolerance of the magnets, and there is a risk that the magnets will scatter during positioning or use.

[0005] Document CN109921525A, for its part, provides a solution for solving the eddy current loss problem by providing orthogonal radial grooves in the entire magnet surface area of the permanent magnet. These orthogonal radial grooves can reduce eddy current losses, but weaken the mechanical strength of the permanent magnet, making it difficult to operate. Summary of the Invention

[0006] The idea on which the present invention is based is to limit the eddy current losses of the permanent magnets of the axial flow rotating motor.

[0007] Another idea on which the present invention is based is to make the permanent magnets of the axial flow rotating motor easier to manufacture.

[0008] Another idea on which the present invention is based is to make it easier to operate when positioning the permanent magnet on the disk of the rotor.

[0009] According to one embodiment, the present invention provides a rotor for an axial flow motor, which is designed to be rotatably mounted about an axis X and positioned axially opposite to a stator. The rotor includes a disk that rotates with an output shaft and a plurality of permanent magnets distributed around the axis X. Each permanent magnet has the shape of a frustum of a disk sector;

[0010] Among them, at least one of the plurality of permanent magnets is integrally formed and consists of a holding portion and a slotted portion. The slotted portion is arranged outside the holding portion in the radial direction of the axis X. The permanent magnet has a plurality of slots, and all of the plurality of slots are formed in the slotted portion.

[0011] Among them, the radial dimension of the holding portion is 10% to 50% of the radial dimension of the permanent magnet. The permanent magnet has a first surface facing the stator and a second surface on the opposite side of the first surface.

[0012] Among them, the plurality of slots include at least one radial slot extending in the radial direction and at least one orthogonal radial slot extending in the direction orthogonal to the radial direction.

[0013] Due to these features, the slots present in the permanent magnet make it possible to greatly limit the eddy current losses, thereby improving the efficiency of the rotating electrical machine. In addition, since the holding portion is not provided with slots that are likely to weaken its strength, the permanent magnet can be easily handled by this particularly robust holding portion. Since the holding portion is as close as possible to the axis X, the slotted portion is in the radially outer region where the eddy current losses are the greatest. Therefore, the position of the slots is optimized to limit these values. Finally, since the permanent magnet is integral, it is easier to manufacture. Therefore, all these features together make it possible to achieve a good balance between reducing eddy current losses and easier manufacturing and handling of the permanent magnet.

[0014] According to some embodiments, such a rotor may have one or more of the following features.

[0015] According to one embodiment, a plurality of the plurality of permanent magnets are integrally formed. Each permanent magnet consists of a holding portion and a slotted portion radially arranged outside the holding portion. Each of the permanent magnets has a plurality of slots, and all of the plurality of slots are formed in the slotted portion.

[0016] According to one embodiment, each of the plurality of permanent magnets is integrally formed and consists of a holding portion and a slotted portion radially arranged outside the holding portion. Each of the permanent magnets has a plurality of slots, and all of the plurality of slots are formed in the slotted portion.

[0017] According to one embodiment, the disk has receiving portions distributed around the axis X, and each permanent magnet is arranged in one of the receiving portions of the disk.

[0018] According to one embodiment, the radial slots are formed from the first surface of the permanent magnet in the thickness direction parallel to the axis X.

[0019] Therefore, the radial slots are formed in the region as close as possible to the stator, where it is beneficial to limit the eddy current losses.

[0020] According to one embodiment, a radial slot is formed extending from a first surface to a second surface of the permanent magnet.

[0021] This enables the eddy current loss to be maximally restricted through the through slot.

[0022] According to one embodiment, the plurality of slots includes a plurality of radially spaced-apart slots.

[0023] According to one embodiment, the plurality of slots includes a plurality of orthogonally radially spaced-apart slots.

[0024] Therefore, by increasing the number of radial slots and / or orthogonally radial slots, the eddy current loss can be further restricted.

[0025] According to one embodiment, the orthogonally radial slot is formed from the first surface of the permanent magnet in a thickness direction parallel to the axis X.

[0026] Therefore, the orthogonally radial slot is formed in a region as close as possible to the stator, where it is beneficial to restrict the eddy current loss.

[0027] According to one embodiment, the orthogonally radial slot extends only over a partial dimension in the thickness direction of the permanent magnet in a thickness direction parallel to the axis X.

[0028] According to one embodiment, the dimension of the orthogonally radial slot in the thickness direction parallel to the axis X is 10% to 90% of the dimension of the permanent magnet in the thickness direction.

[0029] Therefore, since the thickness of the orthogonally radial slot is within this range, the restriction of the eddy current loss can be optimized while maintaining the permanent magnet.

[0030] According to one embodiment, the orthogonally radial slot is a first orthogonally radial slot, wherein the plurality of slots includes a second orthogonally radial slot having a dimension in the thickness direction of 10% to 90% of the dimension of the permanent magnet in the thickness direction, the second orthogonally radial slot being formed from the second surface of the permanent magnet in the thickness direction, and the first orthogonally radial slot and the second orthogonally radial slot being spaced apart from each other by a non-zero distance in the radial direction.

[0031] According to one embodiment, the plurality of slots includes a plurality of first orthogonally radial slots and a plurality of second orthogonally radial slots, the first orthogonally radial slots being alternating with the second orthogonally radial slots in the radial direction.

[0032] According to one embodiment, the permanent magnet of the rotor and the disk are held in position relative to each other by overmolding.

[0033] According to one embodiment, the present invention also provides an axial flow motor, comprising:

[0034] - A housing that defines an internal space;

[0035] - At least one of the aforementioned rotors, which is rotatably mounted about an axis X in the internal space of the housing;

[0036] - At least one stator, the at least one stator being positioned in the internal space, axially opposite to the rotor, and having a stator body that is equipped with teeth and coils, the teeth protruding towards the rotor and being distributed around the axis X, each coil including a winding mounted around one of the teeth.

[0037] According to one embodiment, the present invention further provides a motor vehicle including the aforementioned motor. Description of the Drawings

[0038] The present invention will be better understood from the following description of multiple specific embodiments of the present invention. Other objects, details, features, and advantages of the present invention will become more apparent. These embodiments are provided only as non - restrictive illustrations and with reference to the drawings:

[0039] Figure 1 A cross - sectional schematic view of an axial - flow rotary electric machine including one rotor and two stators is shown.

[0040] Figure 2 A cross - sectional schematic view of an axial - flow rotary electric machine including two rotors and one stator is shown.

[0041] Figure 3 Shown is Figure 1 A perspective view of a disk and permanent magnets of the rotor of the axial - flow rotary electric machine in

[0042] Figure 4 A perspective view of the permanent magnets themselves of the rotor of the axial - flow rotary electric machine is shown.

[0043] Figure 5 A perspective view of the rotor of the axial - flow rotary electric machine after overmolding is shown. Detailed Description of the Embodiments

[0044] Figure 1 A permanent - magnet - type axial - flow rotary electric machine 1 is shown, including a housing 10 that defines an internal space 11, two stators 2 positioned in the internal space 11, and one rotor 3. The stators 2 are respectively placed on both sides of the rotor 3 and are axially opposite to the rotor 3. The rotor 3 is axially spaced apart from the two stators, thereby forming two gaps.

[0045] In the said example, the axial - flow electric machine 1 is configured to operate in a motor mode and a generator mode. In this case, it is a permanent - magnet synchronous motor for electric vehicle propulsion.

[0046] A vehicle shall be understood as any vehicle capable of transporting goods or persons, such as a car, a truck, a bicycle or a drone.

[0047] The power of the electric motor can be between 4 kW and 850 kW. In the example considered, the operating voltage of the electric motor is advantageously less than 60 volts, preferably 48 volts. Generally, the torque provided by the electric motor is between 30 N.m and 2000 N.m. As an alternative, the electric motor can have an operating voltage greater than 60 V, or even greater than 80 V or greater than 100 V, especially an operating voltage of 300 V or higher. In this case, the power of the electric motor can be between 60 kW and 300 kW.

[0048] The axial-flow electric motor 1 includes an output shaft 4 extending along a fixed axis X of the rotor 3, and this axis X passes through the rotor 3 and the stator 2. The output shaft 4 has an output pinion meshing with a reduction gear (not shown).

[0049] The rotor 3 has a disk 5 which rotates together with the output shaft 4 and has a hole 6 through which the output shaft 4 passes. The disk 5 also has a receiving portion 7 which is evenly distributed around the axis X and includes permanent magnets 8 having a shape such as a sector of a disk, for example. The rotor 3 will be described in more detail in conjunction with Figures 2 to 4 The rotor 3 will be described more specifically.

[0050] Each stator 2 has a stator body provided with a plurality of electrical windings and a plurality of teeth supporting the electrical windings. The housing is configured to support the plurality of teeth.

[0051] The windings on the teeth together form the overall winding of the stator, such as a three-phase type. These windings are composed of the number of turns of wire wound around each tooth.

[0052] The windings are configured to be driven by electricity to generate a magnetic field, and this magnetic field can generate an output torque together with the rotor 3 of the axial-flow electric motor 1.

[0053] Figure 2 Another embodiment of the axial-flow rotary electric motor 1 is shown. Specifically, contrary to the embodiment in Figure 1 In the embodiment in Figure 2 the axial-flow rotary electric motor 1 has one stator 2 and two rotors 3 which are respectively placed on both sides of the stator 2 and axially face the stator 2.

[0054] Figure 3 The disk 5 of the rotor 3 and the associated permanent magnets 8 are shown more specifically.

[0055] As Figure 3 shown, each permanent magnet 8 has a frustum-of-a-cone disk sector shape and is evenly distributed around the axis X. Each permanent magnet 8 is placed in one of the receiving portions 7 of the disk 5. Therefore, the receiving portion 7 has a shape complementary to that of the permanent magnet 8.

[0056] In the case of the double-stator motor 1 in Figure 1 , the permanent magnet 8 is arranged in the receiving part 7 such that the first surface 12 of the permanent magnet 8 protrudes from one side of the disk 5 facing one of the stators 2, while the second surface 13 opposite the first surface 12 protrudes from the other side of the disk 5, the other side facing the other of the stators 2.

[0057] In Figure 2 the case of the double-rotor motor 1, the permanent magnet 8 is fixed to the flange and has a single surface protruding from the disk 5 and intended to face the stator 2.

[0058] The permanent magnet 8 is more specifically described in Figure 4 . As shown in this figure, each permanent magnet 8 is integrally formed and consists of two parts: a holding part 14 and a slotted part 15 arranged radially outside the holding part 14.

[0059] Each permanent magnet 8 also has a plurality of slots, all of which are formed in the slotted part 15, so that the holding part 14 does not have any slots.

[0060] Advantageously, the radial dimension of the holding part 14 measured in the radial direction R is 10% to 30% of the radial dimension of the permanent magnet 8. In Figure 3 and Figure 4 the example shown, the radial dimension of the holding part 14 is approximately 26% of the radial dimension of the permanent magnet 8.

[0061] The radial dimension of the slotted part 15 itself is complementary to the radial dimension of the holding part 14, i.e., approximately 74% of the total radial dimension of the permanent magnet 8 in the example.

[0062] To limit eddy current losses, the permanent magnet 8 has radial slots 16 in the plurality of slots, which extend and are spaced apart in the radial direction R. In Figure 4 the example shown, there are three radial slots 16, so that the slotted part 15 of the permanent magnet 8 is divided into four parts in the orthogonal radial direction O. In other embodiments, there may be more or fewer radial slots depending on the size of the permanent magnet 8.

[0063] Each radial slot 16 is formed from the first surface 12 all the way through to the second surface 13 in the thickness direction E parallel to the axis X.

[0064] Furthermore, to limit eddy current losses, the permanent magnet 8 has orthogonal radial slots in the plurality of slots, which extend parallel to each other and are spaced apart in the orthogonal radial direction O.

[0065] In the orthogonal radial slots, the permanent magnet 8 has a first orthogonal radial slot 17 formed from the first surface 12 in the thickness direction E and a second orthogonal radial slot 18 formed from the second surface 13 in the thickness direction E. Additionally, as Figure 4 shown, the first orthogonal radial slot 17 and the second orthogonal radial slot 18 alternate in the radial direction R.

[0066] The dimensions of both the first orthogonal radial slot 17 and the second orthogonal radial slot 18 in the thickness direction E are advantageously 10% to 90% of the dimension of the permanent magnet 8 in the thickness direction E. In the Figure 4 example shown, the dimensions of the orthogonal radial slots 17, 18 in the thickness direction are approximately 60% of the dimension of the permanent magnet 8 in the thickness direction E.

[0067] In the Figure 4 example shown, there are six first orthogonal radial slots 17 and six second orthogonal radial slots 18. In other embodiments, depending on the size of the permanent magnet 8, there may be more or fewer radial slots. Additionally, the number of the first orthogonal radial slots 17 may be different from the number of the second orthogonal radial slots 18, for example, five first orthogonal radial slots 17 and four second orthogonal radial slots 18.

[0068] In an embodiment not shown, the slotted portion 15 may have only the first orthogonal radial slot 17 or the second orthogonal radial slot 18, for example, if the motor 1 has a single stator 2 and two rotors 3.

[0069] The slots 16, 17, 18 are formed, for example, by wire cutting or laser cutting operations.

[0070] Figure 5 Shown is the rotor 3 after the overmolding step for holding the permanent magnet 8 in the receiving portion 7 of the disk 5. Specifically, the disk 5 enables circumferential and radial positioning of the magnet before overmolding, and as Figure 5 shown, during the overmolding step of precisely locking the positions of the various permanent magnets 8, the entire disk 5 and the permanent magnets 8 of the rotor 3 are encapsulated by a resin layer 19, which is preferably made of a polymeric material. Figure 5 The holes 20 shown in [reference] represent the positions of pins that are positioned in the mold to ensure the precise position of the permanent magnet 8 during the overmolding process.

[0071] Although the invention has been described in connection with multiple specific embodiments, it is obvious that the invention is not limited thereto, and the invention includes all technical equivalents of the described method and their combinations, as long as they fall within the scope of the invention.

[0072] The use of the verbs “have”, “comprise”, “contain” or “include” and their conjugations does not exclude the presence of elements or steps not recited in the claims.

[0073] In a claim, any reference signs in parentheses shall not be construed as limiting the claim.

Claims

1. A rotor (3) for an axial flow motor (1), intended to be rotatably mounted about an axis X and positioned axially opposite to a stator (2), the rotor (3) comprising a disk (5) rotating together with an output shaft (4) and a plurality of permanent magnets (8) distributed about the axis X, each permanent magnet (8) having the shape of a truncated disk sector; in, At least one of the plurality of permanent magnets (8) is integrally formed and consists of a retaining portion (14) and a slotted portion (15), wherein the slotted portion (15) is arranged outside the retaining portion (14) along a radial direction (R) of an axis X, and the permanent magnet (8) has a plurality of slots, all of which are formed on the slotted portion (15). The radial dimension of the retaining portion (14) is 10% to 50% of the radial dimension of the permanent magnet (8), and the permanent magnet (8) has a first surface (12) facing the stator (2) and a second surface (13) on the opposite side of the first surface (12). The plurality of grooves include at least one radial groove (16) extending in a radial direction (R) and at least one orthogonal radial groove extending in an orthogonal radial direction (O).

2. The rotor (3) according to claim 1, wherein: The radial groove (16) is formed from the first surface (12) of the permanent magnet (8) along a thickness direction parallel to the axis X.

3. The rotor (3) according to claim 2, wherein: The radial groove (16) is formed from the first surface (12) of the permanent magnet (8) all the way through to the second surface (13).

4. The rotor (3) according to any one of claims 1 to 3, wherein: The plurality of grooves includes a plurality of radial grooves spaced apart from one another.

5. The rotor (3) according to any one of claims 1 to 4, wherein: The plurality of grooves includes a plurality of orthogonal radial grooves spaced apart from one another.

6. The rotor (3) according to any one of claims 1 to 5, wherein: The orthogonal radial grooves are formed from the first surface (12) of the permanent magnet (8) along a thickness direction parallel to the axis X.

7. The rotor (3) according to claim 6, wherein: In the thickness direction parallel to the axis X, the orthogonal radial grooves extend only over a partial dimension of the permanent magnet (8) in the thickness direction.

8. The rotor (3) according to claim 7, wherein: The orthogonal radial grooves are first orthogonal radial grooves (17), wherein the plurality of grooves include second orthogonal radial grooves (18), the dimension of the second orthogonal radial grooves (18) in the thickness direction is 10% to 90% of the dimension of the permanent magnet (8) in the thickness direction, the second orthogonal radial grooves (18) are formed from the second surface (13) of the permanent magnet (8) along the thickness direction, and the first orthogonal radial grooves (17) and the second orthogonal radial grooves (18) are spaced apart by a non-zero distance in the radial direction (R).

9. The rotor (3) according to claim 8, wherein: The plurality of grooves includes a plurality of first orthogonal radial grooves and a plurality of second orthogonal radial grooves, the first orthogonal radial grooves alternating with the second orthogonal radial grooves in the radial direction (R).

10. The rotor (3) according to any one of claims 1 to 9, wherein: The permanent magnets (8) of the rotor (3) and the disc (5) are held in position relative to each other by overmolding.

11. An axial flow motor (1), comprising: - the outer shell, defining the interior space; - at least one rotor (3) according to any one of claims 1 to 10, the rotor (3) being rotatably mounted about an axis X in the inner space of the housing; - at least one stator (2), located in the inner space, axially opposite the rotor (3), and having a stator (2) body, the stator (2) body being provided with teeth and coils, the teeth protruding towards the rotor (3) and distributed around the axis X, each coil comprising a winding mounted around one of the teeth.

12. A motor vehicle comprising an electric machine according to claim 11.

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