Rotor for an axial flux machine having a protective device, and axial flux machine

Abstract

The invention relates to a rotor (1) for an electric axial flux machine (2), having a rotor main part (3) which can be secured to a rotor shaft, wherein a protective device (5) which is connected to the rotor main part (3) for conjoint rotation and serves as a heat shield is at least partly mounted on an end face (4) of the rotor main part (3). The invention also relates to an axial flux machine (2) having the aforementioned rotor (1) and a stator (6), said rotor (1) and stator (3) interacting in order to generate a torque.

Description

[0001] Rotor for an axial flux machine with a protective device; and axial flux machine

[0002] The invention relates to a rotor for an electric axial flux machine, with a rotor body which can be attached to a rotor shaft.

[0003] During operation of an axial flux machine, the rotor heats up considerably because it comes into contact with the ambient air, creating air friction against the rotor body. This results in air friction losses, which affect the performance of the axial flux machine during continuous operation. A variety of methods are known for cooling the rotor of an axial flux machine. Examples include cooling via a stator, cooling via ambient air, or cooling via wet-running electric motors.

[0004] According to the prior art patent US 2022 / 0329132 A1, an axial-field rotating energy system is known which has a housing and rotors with an axis of rotation that are rotatably connected to the housing. Each rotor contains a magnet. A stator assembly is arranged axially between the rotors and coupled to the housing. The stator assembly has a printed circuit board (PCB). The PCB comprises a plurality of layers, and each layer has coils. A shaft is connected to the rotors and the housing. The shaft can distribute a liquid coolant between the rotors and the stator assembly. The housing can include a tray for collecting the liquid coolant.

[0005] Further state of the art can be found in US 2021 / 0288554 A1 and US 2018 / 0145574 A1, whereby cooling of the rotor is always provided.

[0006] The object of the present invention is to provide an alternative rotor with an optimized thermal state. This is achieved in the present rotor by arranging at least a protective device, serving as a heat shield, at least partially on a (first) end face of the rotor body. This device is rotationally connected to the rotor body, so that air friction occurs / generates against the heat shield when the rotor rotates. Overall, this protective device ensures that heating of the rotor due to air friction is at least reduced or prevented. Instead of the rotor heating up, the heat shield itself is heated by the air friction. This results in a shift in the heat generation pattern, thereby having less of an impact on the rotor's performance during continuous operation.

[0007] Advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0008] It is advantageous if the heat shield extends at least partially, preferably completely, along a radial outer surface of the rotor body and / or partially along a second end face. Depending on the design, various arrangements of the protective device are possible.

[0009] It is advantageous to have an axial and / or radial air gap between the rotor body and the protective device. An axial air gap allows air to be positioned between the rotor and the protective device. The rotation of the rotor can also accelerate the air in the air gap. This reduces or eliminates losses at the rotor and also minimizes heat generation at the rotor, because the protective device, acting as a heat shield, is heated instead. A radial air gap allows air to be trapped between the rotor body and the protective device. This acts as insulation to reduce heat transfer.

[0010] In a first advantageous embodiment, the protective device can be a layer / coating applied separately to the rotor body. The layer can preferably be applied directly to the outer contour of the rotor. Preferably, the layer can be applied to the first end face in a radially outer section. This reduces air friction on the rotor body. In other words, the additional layer on the rotor body prevents heat generation on the rotor and shifts it to the surface of the layer.

[0011] It is advantageous if the coating is sprayed or applied with adhesive. Preferably, one surface, i.e., the side facing the environment, is smooth / flat / straight in the radial direction. This further reduces air friction.

[0012] It is advantageous if the layer material has lower thermal conductivity and higher temperature resistance than the rotor base. In other words, the layer has poor thermal conductivity, so only the layer surface gets hot, but the rotor itself does not.

[0013] Furthermore, the layer can have a black tint. This ensures that as much heat energy as possible is emitted and not transferred to the rotor body.

[0014] In a second advantageous embodiment, the protective device can be a component / part / body manufactured separately from the rotor base body.

[0015] The component can be solid or hollow with a free space, in other words, a hollow body. The protective device can be designed as a circular disk. The circular disk is preferably spaced apart from the first end face of the rotor body. Preferably, the disk is rotationally fixed to the rotor body by means of an axial connecting piece. Preferably, the connecting piece itself has a diameter that is (significantly) smaller than that of the disk. This allows the heat to be directed into thermally non-critical areas / zones. Alternatively, the component can be designed as an annular disk, in other words, a ring. The annular disk can at least partially rest directly against the end face and / or can be bonded to the end face. The ring can also be designed as a hollow ring.

[0016] The invention is not limited to providing only one protective device. The previously described embodiments / variants of the protective device can be combined with one another as desired, so that several protective devices are arranged on one rotor body.

[0017] The invention also relates to an electric axial flux machine with at least one previously described rotor and stator, wherein the rotor and the stator cooperate to generate a torque.

[0018] It is advantageous if a protective device serving as a heat shield is positioned at least partially on an end face of the rotor body facing away from the stator. In other words, the axial flux machine can be an axial flux machine in an H-arrangement. An H-arrangement, as described here, describes the arrangement of two rotors on opposite axial sides of the stator. The second end face described above faces one side of the stator, while the first end face faces away from the stator.

[0019] Several advantageous embodiments of the invention are explained in more detail below with reference to a drawing with figures.

[0020] They show:

[0021] Fig. 1 shows a schematic view of a section of an axial flux machine with a rotor according to the invention and a protective device in a first embodiment.

[0022] Fig. 2 shows a rotor according to the invention with a protective device in a second embodiment in a schematic view, Fig. 3 shows a rotor according to the invention with a protective device in a third embodiment in a schematic view,

[0023] Fig. 4 shows a rotor according to the invention with a protective device in a fourth embodiment in a schematic view.

[0024] The figures are purely schematic and serve solely to illustrate the invention. Identical elements are identified by the same reference numerals. Features of the individual embodiments are interchangeable and can be used alternatively or cumulatively.

[0025] Figures 1 to 4 show a rotor 1 according to the invention for an electric axial flux machine 2, with a rotor body 3 which can be attached to a rotor shaft, wherein a protective device 5, serving as a heat shield and non-rotatably connected to the rotor body 3, is arranged at least partially on a (first) end face 4 of the rotor body 3, so that air friction occurs / is generated against the heat shield when the rotor 1 rotates. In Figure 1, the rotor 1 according to the invention is shown in a section of the axial flux machine 2. A stator 6 is also shown next to the rotor 1. The arrangement of the rotor 1 to the stator 6 is oriented such that the protective device 5 is located on the side facing away from the stator, the first end face 4.

[0026] Figures 1 to 4 differ only in the design of the protective device 5. The rotor 1 is identical in each embodiment shown in Figures 1 to 4. The construction of the rotor 1 is described for Figure 1. This construction also applies to Figures 2 to 4.

[0027] The arrangement of stator 6 to rotor 1 with a protective device 5 shown in Fig. 1 is not limited to the illustrated embodiment. The arrangement can also be implemented with a protective device 5 according to the embodiments shown in Figs. 2 to 4. The illustration of the protective device 5 is therefore representative of the further embodiments shown in Figs. 2 to 4.

[0028] For clarity, an axial direction 7, a radial direction 8, and a circumferential direction 9 are defined. The axial direction 7 extends in the direction of a central axis 10 or a rotation axis of the rotor 1, while the radial direction 8 is oriented perpendicular to the central axis 10. The circumferential direction 9 corresponds to a direction of rotation 11 of the rotor 1.

[0029] Fig. 1 shows the rotor 1 according to the invention with the protective device 5 in a first embodiment. The rotor 1 has a first end face 4 and a second end face 12. Furthermore, the rotor has a radial outer surface 13 / outer surface.

[0030] In the first embodiment of Fig. 1, the protective device 5, serving as a heat shield, is designed as a radially continuous disk 14, which is arranged at a distance from the first end face 4. The disk 14 is rotationally fixed to the rotor base body 3 by means of an axially extending

[0031] Connecting piece 15, wherein the diameter of the connecting piece 15 is much smaller than the diameter of the rotor body 3.

[0032] The diameter of the disk 14 corresponds to the diameter of the rotor base body 3. The axial extent of the disk 14 is much smaller than the axial extent of the rotor base body 3.

[0033] Between the first end face 4 and the disk 14, a radially outward-extending air gap 16 is formed in the axial direction 7. Radially, the air gap 16 is limited only by the connecting piece 15. The air in the air gap 16 is accelerated along with the rotor 1 as it rotates about the central axis 10, thus eliminating air friction between the rotor body 3 and the air. Air friction arises between the disk 14 and the air, causing the disk 14 to heat up. Figure 2 shows a schematic view of a second embodiment of the protective device 5. In this embodiment, the protective device 5 is formed by a layer 17 applied to the first end face 4, extending completely circumferentially over the rotor body 3.Layer 17 abuts the first end face 4 at a first (radially outer) section 18 and extends in the axial direction 7 and circumferential direction 9 over the entire radial outer surface 13. Overall, the first end face 4 is only partially covered by layer 17. Layer 17 prevents the rotor body 3 from being exposed to air friction.

[0034] In the present embodiment, layer 17 is smooth / flat, so that no grooves are formed on its surface. The (additional) layer on the rotor base 3 prevents or reduces heat generation at the rotor 1 and shifts it to the surface of layer 17.

[0035] In Fig. 3, the protective device 5 is shown in a schematic view in a third embodiment. The protective device 5 is designed as a component 19 manufactured separately from the rotor body 3. The component 19 abuts the first section 18 of the first end face 4 and a section 20 of the second end face 12. The component 19 is arranged on the first end face 4 in the radially outer section 18, similar to Fig. 2. Thus, the component 19 is only partially located on the first end face 4. Furthermore, a portion of the component 19 is spaced apart from the first end face 4 in a second section 21. Additionally, the component 19 is spaced radially away from the radial outer surface 13 in the axial direction 7. Overall, the component 19 and the rotor body 3 form a cavity 22 in which air is enclosed. This air serves as insulation.

[0036] Figure 4 shows a schematic view of a fourth embodiment of the protective device 5. As in Figure 3, the protective device 5 is designed as a component 19. In this embodiment, the component 19 is designed as a hollow body with a cavity 22, resulting in an air inclusion within the cavity 22 of the component 19. The component 19 rests against the radially outer section 18 at the first end face 4 and extends completely along the radial outer surface 13 in the axial direction 7, resting against it. Thus, the component 19 is only partially located at the end face 4.

[0037] List of reference signs

[0038] rotor

[0039] Axial flux machine

[0040] Rotor body first end face

[0041] Protective device

[0042] stator

[0043] Axial direction

[0044] radial direction

[0045] Circumferential direction

[0046] central axis

[0047] Direction of rotation second end face radial outer side

[0048] disc

[0049] connector

[0050] air gap

[0051] Layer first section (first end face)

[0052] component

[0053] Section (second end face) second section (second end face) cavity

Claims

Patent claims 1. Rotor (1) for an electric axial flux machine (2), with a rotor body (3) which can be attached to a rotor shaft, wherein at least partially on an end face (4) of the rotor body (3) a protective device (5) serving as a heat shield is arranged which is non-rotatably connected to the rotor body (3).

2. Rotor (1 ) according to claim 1 , characterized in that the protective device (5) extends on a radial outer side (13) of the rotor base body (3) and / or at least partially on a further end face (12).

3. Rotor (1 ) according to claim 2, characterized in that an air gap (16) is formed axially and / or radially between the rotor base body (3) and the protective device (5).

4. Rotor (1 ) according to one of claims 1 to 3, characterized in that the protective device (5) is a layer (17) applied separately to the rotor base body (3).

5. Rotor (1 ) according to claim 4 characterized in that the layer (17) is sprayed on or glued on.

6. Rotor (1 ) according to claim 4 or 5, characterized in that the material of the layer (17) has a lower thermal conductivity than the rotor base body (3).

7. Rotor (1 ) according to one of claims 4 to 6, characterized in that the layer (17) has a black color.

8. Rotor (1 ) according to one of claims 1 to 3, characterized in that the protective device (5) is a component (19) manufactured separately from the rotor body (3).

9. Axial flux machine (2) with a rotor (1 ) according to one of claims 1 to 8 and a stator (6), wherein the rotor (1) and the stator (3) cooperate to generate a torque.

10. Axial flux machine according to claim 9, characterized in that a protective device (5) serving as a heat shield is positioned at least partially on an end face (4) of the rotor body (1) oriented towards the side of the stator (6).

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