Axial flux machine having a rotor

Abstract

Proposed is an axial flux machine having at least one rotor (12) and at least one stator (14). The stator (14) comprises a housing (16) and stator cores (18) which are provided within the housing (16) and are arranged along a circumference and have first end structures (24) each with a first end face (26), said first end structures pointing in the axial direction, and opposite second end structures (28) each with a second end face (30), and to which a coil (19) is allocated, wherein a main cooling channel (32) is formed between the housing (16) and the stator cores (18) provided with the coils (19) and / or between adjacent stator cores (18) provided with coils (19), and wherein at least one secondary cooling channel (38) is provided in at least one of the stator cores (18).

Description

[0001] Axial flux machine with one rotor

[0002] The invention relates to an axial flux machine with a rotor.

[0003] More and more electric machines are being used as drives in motor vehicles.

[0004] To date, the most commonly used electric drives are those in the conventional radial design, which are also called radial flux machines.

[0005] In radial electric drives, the rotor made of permanent magnets rotates in a fixed stator, which has electromagnetic tracks, with a narrow air gap provided between the rotor and stator.

[0006] When the electric drive is in operation, the coils of the stator create an alternating magnetic field which interacts with the magnetic fields of the permanent magnets of the rotor, causing the rotor to rotate.

[0007] The axial flux machine operates in a similar way, but has a fundamentally different design. The axial flux machine is often an axially mounted drive system that features at least one disc-shaped stator and one disc-shaped rotor. Alternatively, the axial flux machine can also comprise multiple stator discs and / or rotor discs. The disc-shaped design of the stator and rotor allows the axial flux machine to be constructed with a particularly flat design.

[0008] In the axial flux machine, the electromagnetic flux flows in the axial direction, i.e. parallel to the axis of rotation of the axial flux machine, whereby an air gap extending in the radial direction is formed between the stator and the rotor.

[0009] On the one hand, this achieves an air gap area between the stator and rotor that exceeds the area of ​​a conventional radial-type electrical machine (radial flux machine) with the same overall volume. On the other hand, the magnetic field acting from the stator to the rotor in an axial flux machine can affect the entire diameter of the rotor, so that axial flux machines have a higher torque density and / or power density than radial flux machines for the same diameter.

[0010] In addition, the axial flux machine can reduce the material requirements for copper, from which the stator coils are typically made, as well as a reduced material requirement for iron, from which the stator cores are made.

[0011] The small iron volume results in higher efficiency, which can be achieved over a wider speed range, since the iron volume of the iron cores is directly related to power losses caused by iron losses within the iron cores.

[0012] Furthermore, the low material requirements can reduce production costs.

[0013] Due to these advantages, axial flux machines are an alternative to radial flux machines, especially in motor vehicles.

[0014] However, despite their high efficiency, axial flux machines suffer power losses in the form of heat, which are caused, for example, by the resistance of the coils and iron losses that occur in the iron cores.

[0015] The resulting heat limits the continuous power that can be accessed as well as the duration for which the maximum power (“peak power”) of the electric drive can be accessed, since the wires of the coils, for example, are coated with a varnish insulation that is only resistant up to a certain temperature.

[0016] Therefore, according to the current state of the art, cooling systems are provided for radial flux machines in which the stator cores wound with coils are flushed with a coolant to cool the temperature of the axial flux machine during operation, especially when high power is required. The disadvantage of this is that only the coils and only a portion of the stator cores are flushed, as these are typically housed in a housing and lie flush against the housing with their axially facing end faces.

[0017] This results in high temperatures being generated in the central area of ​​the coil-wound stator cores, even with the cooling system in place, which in turn leads to increased losses in the axial flux machine. Thus, very high temperatures can occur in the stator cores despite the cooling system.

[0018] Based on this, the object of the invention is to provide an axial flux machine with a cooling system that also sufficiently cools the stator cores and protects the stator from overheating, while reducing or even increasing the efficiency of the axial flux machine as little as possible in order to increase the available continuous torque and continuous power if necessary.

[0019] The stated object is achieved according to the invention by an axial flux machine with at least one rotor, at least one stator which comprises a housing and stator cores provided within the housing, which are arranged along a circular circumference and have first end structures pointing in the axial direction, each with a first end face, and opposite second end structures, each with a second end face, and to which a coil is assigned, wherein a main cooling channel is formed between the housing and the stator cores provided with coils and / or between adjacent stator cores provided with coils and wherein at least one secondary cooling channel is provided in at least one of the stator cores.

[0020] The basic idea of ​​the invention is to realize a cooling of the at least one stator core by means of a secondary cooling channel which runs through the stator core.

[0021] In this way, heat generated in the stator core can be removed from the stator core by coolant flowing in the secondary cooling channel.

[0022] The proportional loss of ferromagnetic material compared to a solid stator tooth can be compensated for by the additional cooling effect of the channel(s). Furthermore, the loss of ferromagnetic material could still be compensated for by enlarging the stator core.

[0023] This allows the core temperature of the stator core to be significantly reduced, so that the power loss of the axial flux machine is reduced due to the reduced core temperature of the stator core and thus the efficiency and / or the continuous torque - maximum torque ("peak torque") ratio of the axial flux machine can be increased.

[0024] One aspect provides that the at least one secondary cooling channel is in flow connection with the main cooling channel or the main cooling channel forms a first cooling circuit and the at least one secondary cooling channel forms a second separate cooling circuit.

[0025] If at least one secondary cooling channel is in flow connection with the main channel, the cooling of the stator core for the secondary cooling channel can be realized particularly easily.

[0026] If the secondary cooling channel forms a second separate cooling circuit, this allows the cooling of the stator cores through the secondary cooling channel to be actively controlled and to determine how much cooling power is provided for at least one stator core.

[0027] The at least one secondary cooling channel can run through the area of ​​the center of mass of the stator core.

[0028] Since the center of mass of the stator core is particularly far from the main cooling channel, the highest temperatures occur in this area during operation of the axial flux machine. Therefore, it is particularly advantageous if the secondary cooling channel runs near the center of mass in order to provide cooling capacity in this area.

[0029] Furthermore, the at least one secondary cooling channel can open into the stator core with one end in the region of one end structure of the stator core. In addition, the secondary cooling channel can open out of the stator core with its other end in the region of the other opposite end structure of the stator core. Since the end structures of the stator core are typically located directly against the housing, the coolant that can flow through the main cooling channel does not flow around them. The main cooling channel therefore only forms between the stator core outside the end structures and the housing itself. This can be achieved by the inlet and outlet of the secondary cooling channel in the region of the end structures.

[0030] Furthermore, the at least one secondary cooling channel can be formed by an inlet channel section, a main channel section, and an outlet channel section, wherein the inlet channel section can extend in the region of one end structure of the stator core and the outlet channel can extend in the region of the other end structure of the stator core. Furthermore, the inlet channel section and the outlet channel section can be in flow communication with one another via the main channel section.

[0031] By dividing the secondary cooling channel into the channel section, it can be particularly easily integrated into the stator core through several processing steps.

[0032] The additional benefits can be found in the sections above.

[0033] Furthermore, the opening of the inlet channel section can face a main flow direction formed in the main cooling channel at the respective stator core. Additionally or alternatively, the opening of the outlet channel section can face away from the main flow direction formed in the main cooling channel at the respective stator core.

[0034] By having the opening of the inlet channel section facing the main flow direction forming in the main cooling channel, it is ensured that cooling liquid flows from the main cooling channel into the secondary cooling channel provided in the stator core.

[0035] By orienting the opening of the outlet channel section away from the main flow forming in the cooling channel at the respective stator core, it is ensured that the cooling fluid entering the inlet channel section also continuously exits the outlet channel section. This creates a secondary flow in the secondary cooling channel.

[0036] Furthermore, the at least one stator core can be formed from a base body and pole pieces which form the end structures of the stator core, wherein the main channel section is formed in the base body and the inlet channel section is formed in one pole piece and the outlet channel section is formed in the other pole piece.

[0037] Alternatively, the stator core may consist of two stator core halves, one stator core half having the inlet channel section and part of the main channel section and the other stator core half having the outlet channel section and the other part of the main channel section.

[0038] If the stator core consists of a base body and two pole pieces, the main channel can be easily integrated into the base body, for example, by providing a through hole. Depending on the exact location of the main channel in the base body, the inlet channel section and the outlet channel section must be integrated into the pole pieces accordingly. This can be done, for example, through a blind hole.

[0039] If the stator core is constructed from two stator core halves, the parts of the main channel section in the stator core halves are matched to each other so that when the stator core halves are brought together, the parts of the inlet channel section face each other.

[0040] Furthermore, the base body and the two stator core halves can again consist of laminated cores.

[0041] This allows for extremely cost-effective, simple, and fast production. Furthermore, the dimensions of the stator core can be made larger or smaller depending on the number of laminations used.

[0042] According to a second option, the at least one secondary cooling channel can open into the stator core at one end in the area between the coil and the stator core on the circumference of the stator core. Furthermore, the secondary cooling channel can also open out of the stator core at its other end in the area of ​​the circumference of the stator core. The inlet and outlet of the secondary cooling channel can be on opposite sides of the stator core or on the same side. This allows the secondary cooling channel to provide additional cooling not only to the core of the stator core itself but also to the stator core at the circumference between the coil and the stator core.

[0043] The course of the secondary cooling channel through or on the stator core can be V-shaped or H-shaped.

[0044] Due to the V-shape, the secondary cooling channel can be implemented particularly easily in the stator core, for example by creating two blind holes in the stator core that are in flow connection at their ends.

[0045] The H-shape allows the stator core to be cooled on the one hand around the circumference towards the coil and on the other hand additionally within the stator core itself.

[0046] The secondary cooling channel can have a circular, slot-shaped, slot-shaped or V-shaped cross-section at least along a section.

[0047] A circular cross-section of the secondary cooling channel is particularly easy to manufacture.

[0048] If the cross-section is V-shaped or slot-shaped, the warmest area that forms in the core of the stator core can be cooled particularly well by the slot shape or V-shape.

[0049] Furthermore, such a cross-section allows a particularly large area of ​​the secondary cooling channel to be realized, thus improving the cooling performance.

[0050] In addition, with a slot or V-shaped cross-section, only a small amount of material needs to be removed from the stator core, so that the influence of the secondary cooling channel on the magnetic field is negligible.

[0051] If the slot has a slot-shaped cross-section, it can be easily inserted into the stator core, and this also allows for a particularly large area of ​​the secondary cooling channel, so that the cooling performance of the secondary cooling channel is particularly high. The invention is described below with reference to an embodiment illustrated in the accompanying drawings. These show:

[0052] Figure 1 shows an axial flow machine in a schematic representation;

[0053] Figure 2 shows a stator of an axial flux machine in an exploded view with stator cores according to a first alternative;

[0054] Figure 3 is a sectional view of the stator of Figure 2;

[0055] Figure 4 shows a stator of an axial flux machine in an exploded view with stator cores according to a second alternative;

[0056] Figure 5 is a sectional view of the stator of Figure 4;

[0057] Figure 6a is a sectional view of a stator core with a secondary cooling channel according to the invention according to a first option;

[0058] Figure 6b shows a further sectional view of the stator core with the secondary cooling channel according to the invention according to the first option;

[0059] Figure 6c is a perspective view of the stator core with the secondary cooling channel according to the invention according to the first option;

[0060] Figure 7a is a sectional view of a stator core with a secondary cooling channel according to the invention according to a second option;

[0061] Figure 7b shows a further sectional view of the stator core with the secondary cooling channel according to the invention according to the second option;

[0062] Figure 7c is a perspective view of the stator core with the secondary cooling channel according to the invention according to the second option;

[0063] Figure 8a is a sectional view of a stator core with a secondary cooling channel according to the invention according to a third option;

[0064] Figure 8b shows a further sectional view of the stator core with the secondary cooling channel according to the invention according to the third option;

[0065] Figure 8c is a perspective view of the stator core with the secondary cooling channel according to the invention according to the third option; Figure 9a is a sectional view of a stator core with a secondary cooling channel according to the invention according to a fourth option;

[0066] Figure 9b shows a further sectional view of the stator core with the secondary cooling channel according to the invention according to the fourth option;

[0067] Figure 9c is a perspective view of the stator core with the secondary cooling channel according to the invention according to the fourth option;

[0068] Figure 10a is a sectional view of a stator core with a secondary cooling channel according to the invention according to a fifth option;

[0069] Figure 10b shows a further sectional view of the stator core with the secondary cooling channel according to the invention according to the fifth option;

[0070] Figure 10b is a perspective view of the stator core with the secondary cooling channel according to the invention according to the fifth option;

[0071] Figure 11a is a sectional view of a stator core with a secondary cooling channel according to the invention according to a sixth option;

[0072] Figure 11b is a sectional view of a stator core with a secondary cooling channel according to the invention according to a seventh option; and

[0073] Figure 11c is a sectional view of a stator core with a secondary cooling channel according to the invention according to an eighth option.

[0074] Figure 1 shows schematically an axial flux machine 10 with a rotor 12 and a stator 14.

[0075] The stator 14 has a housing 16 (see Figure 2).

[0076] In addition, the stator 14 comprises stator cores 18 accommodated within the housing 16, which are arranged along a circular circumference.

[0077] According to the first alternative, the stator cores 18 are composed of a base body 20 and two pole shoes 22.

[0078] One of the pole pieces 22 of each stator core 18 forms a first end structure 24 facing in the axial direction with a first end face 26. The respective second pole piece 22 of the stator cores 18 forms an opposite first end structure 24 facing in the axial direction with a second end face 30.

[0079] Both the base body 20 and the pole pieces 22 can be composed of individual sheets or a combination thereof with solid ferromagnetic material.

[0080] In addition, each of the stator cores 18 is assigned a coil 19.

[0081] Furthermore, the stator 14 of the axial flow machine has a main cooling channel 32 which is formed between the housing 16 and the stator cores 18 provided with coils 19 and between adjacent stator cores 18 provided with coils 19 (see Figure 3).

[0082] In order to supply the main cooling channel 32 with coolant, 16 coolant connections 34 are provided on the housing, wherein only one of the coolant connections 34 is supplied with coolant to the main cooling channel 32, while the other coolant connection 34 is discharged with coolant from the main cooling channel 32 (see arrows in Figure 3).

[0083] If the main cooling channel 32 is supplied via the coolant connections 34 as shown in Figure 3, a flow is formed which has the main flow direction H (see arrow in Figure 3).

[0084] The coolant connections 34 are shown in Figure 3 solely as an example and can also be provided at any other conceivable position on the housing 16, wherein with a certain arrangement of the coolant connections 34, two different main flow directions can also result, for example if the coolant connections 34 are arranged opposite one another on the housing.

[0085] Figures 4 and 5 show an axial-fed machine 10 according to a second alternative.

[0086] In contrast to the alternative shown in Figures 2 and 3, in the axial-wound machine 10 according to the second alternative, the stator cores 18 are divided into two stator core halves 36. In each case, one of the stator core halves 36 of a stator core 18 has the first end structure 24 with the first end face 26, and the other stator core half 36 of the respective stator core 18 has the second end structure 28 with the second end face 30.

[0087] The stator core halves 36 can also consist of individual sheet metal elements.

[0088] In addition, both the stator cores 18 of the axial flux machine 10 according to the first alternative and those of the axial flux machine according to the second alternative each have at least one secondary cooling channel 38.

[0089] It is conceivable that the secondary cooling channels 38 are separated from the main cooling channel 32, so that the main cooling channel 32 also forms a first cooling circuit and the secondary cooling channel 38 forms its own second cooling circuit.

[0090] Alternatively, it is also conceivable that the secondary cooling channel 38 is in flow connection with the main cooling channel 32.

[0091] The following will discuss the design of the secondary cooling channel 38 in more detail. This will initially be done using Figures 6a - 6c, with additional possible options being shown in Figures 7a - 11c.

[0092] In Figures 6a-11c, only stator cores 18 according to the second alternative are shown. However, this is only an example. The secondary cooling channels described below can therefore also be provided in stator cores according to the first alternative.

[0093] The cross-section of the secondary cooling channel 38 in Figures 6a - 6c is largely circular.

[0094] The cross-section may also have a different geometry, which will be discussed later in connection with Figures 7a - 10c.

[0095] Furthermore, in Figures 6a-6c, only a single secondary cooling channel 38 is provided in the stator core 18. However, it is also conceivable that multiple secondary cooling channels 38 are provided in the stator core 18. According to Figures 6a-6c, the secondary cooling channel 38 opens into the stator core 18 with one end in the region of one end structure 24, 28 of the stator core 18 and opens out of the stator core 18 with its other end in the region of the other opposite end structure 24, 28 of the stator core 18.

[0096] The secondary cooling channel 38 can run through the area in which the center of mass M is located. According to Figures 6a and 6b, it is clear that the secondary cooling channel 38 runs just below the center of mass M.

[0097] Furthermore, the secondary cooling channel 38 can be formed by an inlet channel section 40, a main channel section 42 and an outlet channel section 44, wherein the inlet channel section 40 and the outlet channel section 44 are in flow connection with one another via the main channel section 42.

[0098] The inlet channel section 40 runs in the region of one end structure 24, 28 and the outlet channel section 44 runs in the region of the other end structure 24 or 28.

[0099] Furthermore, the opening of the inlet channel section 40 can face the main flow direction H forming in the main cooling channel 32, so that coolant can flow into the main channel section 42 via the inlet channel section 40.

[0100] In addition, the opening of the outlet channel section 44 can face away from the main flow direction H formed in the main cooling channel at the respective stator core 18. This ensures that cooling fluid flowing into the secondary cooling channel 38 of the stator core 18 via the inlet channel section 40 can also flow out again.

[0101] According to Figures 6a-6c, in a stator core 18 consisting of two stator core halves 36, one stator core half 36 can have the inlet channel section 40 and part of the main channel section 42. The other stator core half 36 can be provided with the outlet channel section 44 and also have the other part of the main channel section 42. If, however, the stator core 18 consists of a base body 20 and two pole pieces 22 as explained above, it is possible for the main channel section 42 to be formed in the base body 20, for the inlet channel section 40 to be provided in one of the pole pieces 22, and for the outlet channel section 44 to be provided in the other of the pole pieces 22.

[0102] Figures 7a - 7c show a secondary cooling channel 38 whose main channel section 42 has a slot-shaped cross section.

[0103] This allows a particularly large surface to be realized within the stator core 18 without removing too much material from the stator core 18.

[0104] Figures 8a - 8c show a stator core 18 which has a plurality of secondary cooling channels 38, wherein the main channel section 42 of the secondary cooling channels 38 each has a slot-shaped cross section.

[0105] Here, the elongated holes run vertically. Alternatively, a horizontal run of the long-shaped cross-sections is also possible, as shown in Figures 9a - 9c.

[0106] Figures 10a and 10b show a stator core 18 which has a secondary cooling channel 38 with a V-shaped cross section in the region of the main channel section 42.

[0107] This also allows a particularly large area of ​​the main channel section 42 to be achieved in order to provide effective cooling.

[0108] Figures 11a-11c show a further option for the secondary cooling channel 38. Here, the at least one secondary cooling channel 38 opens into the stator core with one end in the area between the coil 19 and the stator core 18 at the circumference of the stator core 18.

[0109] At its other end, the secondary cooling channel 38 opens out of the stator core.

[0110] This can be done either on the same side of the stator core 18 as shown in Figure 11a or on the opposite side of the stator core 18 as shown in Figures 11b and 11c. Accordingly, the course of the secondary cooling channel 38 can be V-shaped (Figure 11a), I-shaped (Figure 11b) or H-shaped (Figure 11c).

[0111] Furthermore, all of the above explanations regarding the previous options can also be applied to the secondary cooling channels 38 shown in Figures 11 a - 11 c. In particular, the explanations regarding the cross-section of the secondary cooling channels.

Claims

Patent claims 1. An axial flux machine having at least one rotor (12), at least one stator (14) comprising a housing (16), and stator cores (18) provided within the housing (16), which are arranged along a circular circumference and have first end structures (24) pointing in the axial direction, each having a first end face (26), and opposite second end structures (28), each having a second end face (30), and to which a coil (19) is assigned, wherein a main cooling channel (32) is formed between the housing (16) and the stator cores (18) provided with coils (19) and / or between adjacent stator cores (18) provided with coils (19), and wherein at least one secondary cooling channel (38) is provided in at least one of the stator cores (18).

2. Axial flow machine according to claim 1, characterized in that the at least one secondary cooling channel (38) is in flow connection with the main cooling channel (32) or the main cooling channel (32) forms a first cooling circuit and the at least one secondary cooling channel (38) forms a second separate cooling circuit.

3. Axial flow machine according to claim 1 or 2, characterized in that the at least one secondary cooling channel (38) runs through the region of the center of mass (M) of the stator core (18).

4. Axial flow machine according to one of the preceding claims, characterized in that the at least one secondary cooling channel (38) opens into the stator core (18) with its one end in the region of one end structure (24, 28) of the stator core (18), and that the secondary cooling channel (38) opens out of the stator core (18) with its other end in the region of the other opposite end structure (24, 28) of the stator core (18).

5. Axial flow machine according to one of the preceding claims, characterized in that the at least one secondary cooling channel (38) is formed by an inlet channel section (40), a main channel section (42) and an outlet channel section (44), wherein the inlet channel section (40) runs in the region of one end structure (24, 28) of the stator core (18) and the outlet channel section (44) runs in the region of the other end structure (24, 28) of the stator core (18) and the inlet channel section (40) and the outlet channel section (44) are in flow connection with each other via the main channel section (42).

6. Axial flow machine according to claim 5, characterized in that the opening of the inlet channel section (40) faces a main flow direction (H) forming in the main cooling channel (32) on the respective stator core (18) and / or that the opening of the outlet channel section (44) faces away from the main flow direction (H) forming in the main cooling channel (32) on the respective stator core (18).

7. Axial flux machine according to claim 5 or 6, characterized in that the at least one stator core (18) is formed from a base body (20) and pole shoes (22) which form the end structures (24, 28) of the stator core (18), wherein the main channel section (42) is formed in the base body (20) and the inlet channel section (40) is formed in one of the pole shoes (22) and the outlet channel section (44) is formed in the other pole shoe (22), or the stator core (18) consists of two stator core halves (36), wherein one stator core half (36) has the inlet channel section (40) and a part of the main channel section (42) and the other stator core half (36) has the inlet channel section (40) and the other part of the main channel section (42).

8. Axial flux machine according to one of claims 1 to 3, characterized in that the at least one secondary cooling channel (38) opens into the stator core (18) with its one end in the region between the coil (19) and the stator core (18) on the circumference of the stator core (18) and that the secondary cooling channel (38) opens out of the stator core (18) with its other end also in the region of the circumference of the stator core (18).

9. Axial flow machine according to claim 8, characterized in that the course of the secondary cooling channel (38) through or on the stator core (18) is V-shaped or H-shaped.

10. Axial flow machine according to one of the preceding claims, characterized in that the secondary cooling channel (38) has a circular, slot-shaped, elongated hole-shaped, V-shaped cross-section at least along a section.

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