Axial-flux electric machine and cover of an axial-flux electric machine

Abstract

The present invention relates to an axial-flux electric machine (1) comprising at least one cover (1), wherein the cover (1) comprises at least one cooling channel (5) through which a cooling gas flows, wherein the at least one cooling channel (5) comprises at least one expansion region (E) designed to ensure a controlled expansion of the cooling gas.

Description

“AXIAL FLUX ELECTRICAL MACHINE AND COVER OF AN AXIAL FLUX ELECTRICAL MACHINE” FIELD OF INVENTION

[0001] The present invention relates to an axial flux electrical machine and, more specifically, to an axial flux motor or generator. BACKGROUND OF THE INVENTION

[0002] Axial electromagnetic flux electric machines are widely known in the art and essentially comprise at least one stator and at least one disc-shaped rotor, in which the electromagnetic flux travels in the axial direction of the machine's rotating shaft. They can include both electric motors and electric generators.

[0003] In one of the known solutions for cooling axial flux motors, an external mechanism, such as a pump or compressor, pumps coolant into the motor (preferably inside the frame and / or stator) so that the coolant can extract heat from the motor. The greater the heat extraction capacity, the higher the power density (kW / kg) at which the motor can operate.

[0004] Thus, it is known from the prior art to form cooling channels for the passage of coolant fluid through engine components.

[0005] Document EP2606561, for example, shows an electrical machine with an annular chamber through which a cooling medium can circulate around the stator coils.

[0006] Document KR101999860, in turn, discloses an electric motor with a cooling solution comprising a coolant distribution chamber that includes a portion of the introduced coolant and a second coolant distribution path to guide another portion of the coolant to the side of the rear cover.

[0007] Document WO2019 / 171318 discloses a cooling component for an electric motor comprising a channel defined by an outer ring, an inner ring concentric to the outer ring and linear segments extending radially from the inner ring towards the outer ring. OJECTIVES OF THE INVENTION

[0008] It is one of the objectives of the present invention to provide a machine axial flow electric with a cooling system with efficient cooling performance.

[0009] It is a further object of the present invention to provide an axial flux electric machine with a cooling system that utilizes temperature reduction by expansion of the cooling gas to improve the cooling performance of an axial flux electric machine. Summary of the Invention

[0010] The present invention relates to an electrical machine cover and an axial flux electrical machine comprising such an electrical machine cover.

[0011] The axial flux electric machine comprises a housing with at least one cover, the at least one cover comprising at least one cooling channel through which a cooling gas passes, the at least one cooling channel comprising at least one expansion region designed to ensure a controlled expansion of the cooling gas.

[0012] The cover comprises a refrigerant inlet and a refrigerant outlet and, preferably, the expansion region has a cross-sectional area with a cross-sectional expansion ratio of between 150% and 1000% from the refrigerant inlet to the refrigerant outlet.

[0013] In one embodiment of the invention, the expansion region is formed as a part of the geometry of the cooling channel.

[0014] The cooling channel can be formed directly integrated with the lid. However, in an alternative embodiment, the cooling channel can be formed in a structure coupled to the lid. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be described below in more detail, with reference to the attached drawings, in which:

[0016] Figure 1 is a perspective view of an axial flux electrical machine according to an embodiment of the present invention;

[0017] Figure 2 is a plan view of an axial flux electrical machine according to an embodiment of the present invention;

[0018] Figure 3 - is a schematic view showing the assembly of some internal components of an axial flux electrical machine according to an embodiment of the present invention; and

[0019] Figure 4 is a schematic illustration of four possible configurations for a cooling channel of an axial flux electric machine according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] Figure 1 shows an axial flux electric motor according to an embodiment of the present invention.

[0021] Although the present invention is described as embodied in an electric motor, it should be understood that the solution of the present invention could equally be applied to other axial flux electric machines, such as axial flux generators. The internal components and operation of an axial flux electric machine are known to those skilled in the art, and therefore, this description will focus only on the components necessary for understanding the invention.

[0022] As can be seen in figure 1, in the illustrated embodiment, the electric motor comprises at least a cover 1, a central through hole 2 and coolant inlet holes 3 and outlet holes 4. The through hole 2 is intended for receiving a shaft, however, it should be understood that in other embodiments of the invention, the shaft could be integrated into the motor.

[0023] It should be noted that the machine may comprise a housing with a body closed by a lid or lids connected together to form a casing. However, it should be understood that the casing could be formed differently, for example, with a central body part and two side lids.

[0024] As illustrated in the figures, the cover 1 comprises at least one cooling channel 5 for the circulation of a refrigerant fluid and, more specifically, of a refrigerant gas.

[0025] This refrigerant cools the machine's internal components and, naturally, cools those adjacent to the cover more efficiently. Figures 1 and 2 schematically show the refrigerant gas cooling circuit C.

[0026] The at least one cooling channel 5, which is illustrated for visualization in figures 1 and 2, can be formed directly integrated with the cover, for example, as a casting or machined part, or it may be formed into a coupled structure, for example, into a coupled inner overcover.

[0027] The present invention proposes the formation of at least one expansion region E in the at least one cooling channel 5. This expansion region is designed to ensure a controlled expansion of the cooling gas, so that the gas temperature reduces to adequate levels to avoid external freezing and abrupt pressure drops, maintaining the efficiency of the cooling circuit C.

[0028] Thus, according to the present invention, the cooling channel 5 requires an expansion of the cross-sectional area between the refrigerant inlet and outlet. Such expansion preferably has a cross-sectional expansion ratio between 150% and 1000% from the refrigerant inlet to the refrigerant outlet.

[0029] Such expansion may preferably occur smoothly, as shown in the exemplary embodiment of Figure 4a, or abruptly, as shown in Figure 4b. In order to maintain smooth expansion, the area expansion rate per channel length should not exceed 4000% / m.

[0030] In embodiments of the invention, the expansion region E is formed as part of the geometry of the cooling channel and comprises a region capable of controlling the expansion of a gas passing through it.

[0031] The cross-section of channel 5 can have different shapes, such as circular, elliptical, rectangular, trapezoidal, or polygonal. Cooling channels can also be designed with custom or irregular shapes to meet specific site conditions or flow requirements, as long as the area expansion ratio criteria are met.

[0032] As shown in figure 3, in one embodiment of the present invention, the stator 6 of the machine is coupled to the cover 1 and, in this embodiment, the at least one cooling channel 5 is particularly efficient for cooling the stator 6.

[0033] Thus, it should be emphasized that, in the present invention, the one or more expansion regions can be strategically provided with defined geometries and locations to avoid hot spots in the fixed stator. on the inside of the lid.

[0034] In this embodiment, a bearing 7 can also be provided for receiving the shaft 8 of the machine and this bearing 7 is also efficiently cooled by the cooling system (cooling channel 5) of the cover 1.

[0035] In embodiments of the invention, the lid 1 may further comprise a seal to prevent leakage of the refrigerant gas.

[0036] Figure 4 shows a schematic illustration of four possible configurations a, b, c, and d for a cooling channel of an axial flux electric machine according to the present invention. In these exemplary embodiments, the expansion regions E are formed by different geometries. It should be noted that the expansion region could have other geometries, as long as it allows for controlled expansion of the cooling gas.

[0037] In this sense, from the front view, as shown in figure 4, the channels are of different shapes between the refrigerant inlet and the refrigerant outlet, such as circular - see figures 4a and 4b, polygonal (figure 4c) and serpentine (figure 4d).

[0038] Thus, the present invention, by providing at least one expansion region E in the cooling channel, uses the temperature reduction due to gas expansion to improve the cooling performance of an axial flow machine.

[0039] Although the described embodiments focus on a cover 1 with the cooling channel, it should be understood that the machine could have two covers with cooling channels that close together, including or not a housing body between these covers.

[0040] Having described examples of embodiments of the present invention, it should be understood that the scope of the present invention encompasses other possible variations of the described inventive concept, being limited solely by the content of the claims alone, including possible equivalents.

Claims

CLAIMS 1. Axial flux electric machine comprising at least one cover (1) characterized in that the cover (1) comprises at least one cooling channel (5) through which a cooling gas passes, wherein the at least one cooling channel (5) comprises at least one expansion region (E) designed to ensure a controlled expansion of the cooling gas.

2. Machine according to claim 1, characterized in that the cover further comprises a refrigerant inlet (3) and a refrigerant outlet (4) and in which the expansion region has a cross-sectional area with a cross-sectional expansion ratio between 150% and 1000% from the refrigerant inlet (3) to the refrigerant outlet (4). Machine according to claim 1 or 2, characterized in that the expansion region (E) is formed as a part of the geometry of the cooling channel (5). Machine according to any one of claims 1 to 3, characterized in that the cooling channel (5) is formed directly integrated with the lid (1). Machine according to any one of claims 1 to 3, characterized in that the cooling channel (5) is formed in a structure coupled to the cover (1).

6. Cover (1) for an axial flux electric machine characterized in that it comprises at least one cooling channel (5) through which a cooling gas passes, wherein the at least one cooling channel (5) comprises at least one expansion region (E) designed to ensure a controlled expansion of the cooling gas.

7. Lid, according to claim 6, characterized by the fact that it further comprises a refrigerant fluid inlet (3) and a refrigerant fluid outlet (4) and in which the expansion region has a cross-sectional area with a cross-sectional expansion rate between 150% and 1000% from the refrigerant fluid inlet (3) to the refrigerant fluid outlet (4).

8. Lid according to claim 6 or 7, characterized in that the expansion region (E) is formed as a part of the geometry of the cooling channel (5).

9. Lid according to any one of claims 6 to 8, characterized in that the cooling channel (5) is formed directly integrated with the lid (1).

10. Lid according to any one of claims 6 to 8, characterized in that the cooling channel (5) is formed in a structure coupled to the lid (1).

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