Axial flow machine having a stator and optimised cooling of the pole shoes

Abstract

The invention relates to a stator (1) for an axial flow machine (2), having a stator tooth (3), which is surrounded by a conductor (5) arranged in the form of windings (4), wherein the windings (4) are arranged on the outer side (6) of the stator tooth (3), wherein means (7) are inserted in order to keep a cooling channel (8) free between the stator tooth (3) and the winding (4). The invention also relates to an axial flow machine (2) having a rotor (15), which cooperates with said stator (1) during operation.

Description

[0001] Axial flux machine with one stator and optimized cooling of the pole shoes

[0002] The invention relates to a stator for an axial flux machine, having a stator tooth surrounded by a conductor arranged in windings, wherein the windings are arranged on the outside of the stator tooth.

[0003] Axial flux machines have experienced increased demand in recent years, primarily due to their advantages of a shortened axial length, which saves space and costs, but also due to their high efficiency, which allows for higher torques and higher power density compared to radial-type machines. Axial flux machines are primarily characterized by the disc-shaped design of the stators and rotors, with the number of stators and rotors used varying depending on the selected design of the axial flux machine. Stator teeth are known to be formed on the stator, more specifically on the stator yoke. These teeth are formed, for example, as laminated cores, to reduce losses associated with heating, such as eddy current losses.A pole piece is formed on the stator tooth, which allows the magnetic field lines of the conductor wound around the stator tooth to emerge and distribute them to the rotor. The pole piece is typically armature-shaped. The pole piece is not enclosed by the excitation winding. If the stator tooth is now enclosed by windings, the windings are close to the stator tooth and, accordingly, also close to the pole piece. Because the windings are very close to the stator tooth, cooling is necessary to reduce heat buildup and further minimize losses caused by heating.

[0004] The object of the present invention is to eliminate or at least partially mitigate the aforementioned disadvantages. The focus is on improved cooling of the pole pieces.

[0005] This is achieved in a generic stator for an axial flux machine by using means to maintain a cooling channel between the stator tooth and the winding. To create the cooling channel between the stator tooth and the winding, at least a gap must be created between the stator tooth and the winding. This gap can then be used to direct cooling fluid to the pole piece via a cooling oil supply.

[0006] Advantageous embodiments are claimed in the subclaims and are explained in more detail below.

[0007] Furthermore, the means can comprise at least one spacer and / or be determined by the arrangement of the windings on the outside of the stator tooth. The implementation of the cooling channel is thus covered by various options. With the help of the spacer, another element is present in the assembly, which creates the distance between the winding and the stator tooth. Depending on the design, the spacer can be attached to various elements of the stator. With the help of the arrangement of the windings, another solution is available that dispenses with additional elements, thus avoiding the redesign of existing elements. For a particularly reliable design of the distance between the winding and the stator tooth, both solutions can be combined using the spacer and the arrangement of the winding. This allows for a flexible design depending on the application.

[0008] Furthermore, the spacer can be an integral part of the stator tooth, a base insulation of the winding, an insulation layer of the stator tooth, or a stator cover, or the windings can be aligned relative to each other and the surface of the stator tooth in such a way that the cooling channel is enforced. If the spacer is designed as an integral part of the stator tooth, it is formed directly on the pole piece, for example, as part of the manufacturing process. The spacer is preferably designed in the form of a raised portion. The geometric shape of the raised portion in cross-section is, for example, rectangular, semicircular, or tapered. The height of the spacer, which defines the size, for example, the length in the radial direction of the cooling channel, among other things, must be designed according to the amount of cooling oil flow required. Accordingly, the distance between the stator tooth and the winding can be larger or smaller.If the spacer is formed on the base insulation of the winding, it is directly formed by overmolding the wound conductor during the production of the base insulation. If additional insulation is formed on the stator tooth, for example as a result of slot insulation, the insulation layer can be implemented directly with spacers. The spacer can also be formed directly on the stator cover, whereby the spacer is also formed on the stator cover directly during the manufacturing process. If the distance between the winding and the stator tooth is implemented without a physical spacer, this is implemented by positioning the windings relative to each other and to the surface of the stator tooth. Depending on the type of winding, for example single-layer or double-layer, different arrangements can be implemented.

[0009] It is advantageous if the spacer projects in the axial and / or radial directions. Depending on the design, a combination or a plurality of spacers formed in the axial and radial directions is possible. If the spacer is preferably designed in the form of a raised portion as an integral component of the stator tooth, it is positioned in the radial direction on the side facing the windings. If the spacer is formed on the stator cover, it has a raised portion comparable to the previously mentioned design on the stator tooth. A combination of axial and radial directions can, for example, be implemented when the spacer is designed as an integral component on the base insulation of the winding.To position the winding between the stator yoke and pole piece and to form the cooling channel, spacers are provided between the base insulation and the underside of the pole piece, as well as between the top of the stator yoke and the base insulation. To space the winding from the outside of the stator tooth, further spacers are provided on the base insulation in the axial direction, spacing the winding including the base insulation from the stator tooth. It is advantageous if at least two spacers are formed in the axial direction to ensure a stable arrangement. It is advantageous if the windings are angled to the radial and axial directions. In a simple winding (1-layer), the windings are inclined at an angle to the underside of the pole piece, which forces a cooling channel.With a double winding (2-layer), the two layers of the windings can be positioned differently from each other. For example, the inner winding is offset from the outer winding, creating a hollow space near the pole piece that can be used as a cooling channel. By eliminating the spacer element to keep the cooling channel clear, one less wear part is required.

[0010] It is further advantageous if the spacer runs at least partially between two windings or acts centrally on a winding. If the spacers are arranged in the axial direction, the spacers can be shaped such that they create a distance between the windings. In an advantageous embodiment, one or more spacers are formed on the insulation layer on the stator tooth. Depending on the application, the spacers have various shapes and act on one winding or run between two windings. With a first spacer, a distance can be created between two windings, preferably the winding oriented towards the underside of the pole piece, between this winding and its adjacent winding. Further spacers can be positioned between the other windings.The spacer preferably has a tapered shape, for example, a point, so that the conductor with the windings can be more easily plugged and secured, and the cooling channel is thereby formed. In a further embodiment, a spacer acts centrally on a winding so that it protrudes axially beyond the other windings and exposes a cooling channel.

[0011] Furthermore, the spacer can act on multiple windings. If the spacer is designed to act centrally on a winding, the shape of the spacer can space the adjacent windings radially from the one winding. If the side surfaces of the spacer are beveled / inclined, this causes the adjacent windings to be offset and positions the winding between the pole piece and the stator yoke.

[0012] It is advantageous if at least one spacer is oriented in the axial direction and at least one further spacer is oriented in the radial direction. The previously described embodiments for forming the cooling channel using the means can be combined with one another.

[0013] In addition, the winding can have local protrusions for forming at least one of the spacers. The local protrusions are formed on the winding of the conductor that is oriented toward the underside of the pole piece. The local protrusions are formed in a transverse direction along the winding, so that the winding forms a wave-shaped profile, for example, which forms the cooling channel. By omitting an element in the form of a molded-on spacer as a means of keeping the cooling channel clear, one less wear part is present.

[0014] In a further advantageous embodiment, the pole piece is a separate element from the stator tooth. The pole piece can be connected separately to the stator tooth in the form of edge elements or in the form of a pole piece plate. The edge elements and the pole piece plate are dimensioned such that they extend beyond the stator tooth in both axial directions to form the armature-like shape in combination with the stator tooth. If the stator tooth and pole piece are separate elements, the pole piece can be molded into the stator cover, for example, simplifying its arrangement relative to the stator tooth.

[0015] In addition, a cooling channel can be formed in the form of a cooling groove formed in the pole piece. These are recesses on the pole piece that allow the cooling oil to flow behind the pole piece to the stator teeth. If the stator teeth are made of electrical lamination stacks, these channels can be created by selectively stamping out a few adjacent lamination layers. The invention also relates to an axial flux machine with a rotor that interacts with a stator during operation.

[0016] Various advantageous embodiments of the invention are explained in more detail below with reference to a drawing with figures.

[0017] They show:

[0018] Fig. 1 an axial flux machine with a stator according to the invention,

[0019] Fig. 2 a stator half of the stator according to the invention according to Fig. 1 ,

[0020] Fig. 3 the stator half including windings around individual stator teeth,

[0021] Fig. 4 a sectional view of a single stator tooth with overmolded winding,

[0022] Fig. 5 a detailed view according to Fig. 4 with cooling channel by means of spacers,

[0023] Fig. 6 the stator tooth according to Fig. 4 with overmolded 2-layer winding,

[0024] Fig. 7 the spacer formed on the pole piece of the stator tooth,

[0025] Fig. 8 shows the spacer formed on an insulation layer of the stator tooth in the radial direction,

[0026] Fig. 9 shows the spacer formed on an insulation layer of the stator tooth, which is arranged between two windings,

[0027] Fig. 10 shows a plurality of spacers formed on the insulation layer of the stator tooth in the axial direction, which are arranged between the windings, Fig. 11 shows the spacer formed on the insulation layer of the stator tooth, which acts centrally on a winding,

[0028] Fig. 12 the stator tooth with separate pole shoes in the form of edge elements with a cooling channel according to Fig. 6,

[0029] Fig. 13 the stator tooth with separate pole shoes in the form of a pole shoe plate with a cooling channel according to Fig. 6,

[0030] Fig. 14 the spacer on the pole shoe edge or pole shoe plate,

[0031] Fig. 15 the spacer formed on the stator cover with injected pole piece in a first embodiment,

[0032] Fig. 16 the spacer formed on the stator cover with filled cavity,

[0033] Fig. 17 a 2-layer winding with a stepped outer turn on the pole piece,

[0034] Fig. 18 pole shoe cooling through cooling grooves on the pole shoe,

[0035] Fig. 19 the pole shoe cooling by slightly inclined windings,

[0036] Fig. 20 the spacer formed on the stator cover with injected pole piece in a second embodiment,

[0037] Fig. 21 the cooling channel by means of local formations in the winding,

[0038] Fig. 22 the cooling channel according to Fig.21 in a side view.

[0039] The figures are merely schematic in nature and serve solely to facilitate understanding of the invention. The same elements are provided with the same reference numerals. Features of the individual embodiments can be interchanged and used alternatively / cumulatively.

[0040] Fig. 1 shows a stator 1 according to the invention for an axial flux machine 2, wherein Fig. 1 shows the complete assembly of the axial flux machine 2. The stator 1 has a stator tooth 3 which is surrounded by a conductor 5 arranged in windings 4, wherein the windings 4 are arranged on the outer side 6 of the stator tooth 3. Means 7 (shown in Fig. 4) are used to keep a cooling channel 8 (shown from Fig. 5) free between the stator tooth 3 and the winding 4. The stator 1 is arranged along an axis of rotation A. The stator 1 has two stator halves 9, 10, a left stator half 9 and a right stator half 10. The left stator half 9 and the right stator half 10 have conductors 5 with windings 4. The stator halves 9, 10 are each surrounded by a stator cover 11, 12 and a housing cover 13, 14, whereby the stator halves 9, 10 are connected to the respective associated housing cover 13, 14.A rotor 15 is arranged between the stator covers 11, 12, and thus also between the stator halves 9, 10. The housing covers 13, 14 are mounted on the rotor 15 by means of bearings 16, 17, 18. A spacer 19 is formed in the radially outer region between the housing covers 13, 14.

[0041] Fig. 2 shows the structure of the stator halves 9, 10 of the stator 1. The stator halves 9, 10 have a stator yoke 20 on which the individual stator teeth 3 are arranged in the circumferential direction. Grooves 21 are formed between the individual stator teeth 3, which keep the space between the individual stator teeth 3 free for the conductors 5 wound in turns 4.

[0042] In Fig. 3, the stator half 9, 10 known from Fig. 2 is arranged with conductors 5 wound on the stator teeth 3 with the windings 4. Furthermore, each stator tooth 3 now has a pole piece 22. The pole pieces 22 rest on the upper surface of the respective stator tooth 3 and define the winding.

[0043] Fig. 4 shows a detailed view of a stator tooth 3 in section. In the embodiment shown, the conductor 5 with its windings 4 is shown in an overmolded form. By means of this overmolded form, the conductor 5 has a base insulation 23. The means 7, here in the form of spacers 24, are formed on this base insulation 23. In the present embodiment, the spacers 24 are formed radially and axially on the base insulation 23. The spacers 24 in the radial direction are each formed with a raised portion on the base insulation 23 between the wound conductor 5 and the underside of the pole piece 22 and, on the other side, between the wound conductor 5 and the top side of the stator yoke 20. The spacers 24 in the axial direction are formed on the base insulation 23 between the wound conductor 5 and the outer side 6 of the stator tooth 3 and are spaced apart from one another in the radial direction.

[0044] In Fig. 5, the arrangement known from Fig. 4 is shown in a detailed illustration with respect to the spacers 24 designed as means 7. With the help of the spacers 24, an optimized cooling oil supply is shown with the help of the cooling channel 8. The path of the cooling channel 8 runs between the underside of the pole piece 22 and the opposite turn 4 of the wound conductor 5 in the axial direction to the outer side 6 of the stator tooth 3, and then in the radial direction along this outer side 6 in the direction of gravity from top to bottom.

[0045] Fig. 6 shows a further embodiment of the arrangement known from Fig. 4 with the spacers 24 used as means 7. The second embodiment shows the conductor 5 in a double winding. The double winding of the conductor 5 is characterized by the two-layer winding in the axial direction. The design of the spacers 24 corresponds to that shown in Fig. 4.

[0046] In Fig. 7, the spacer 24 is formed directly on the underside of the pole piece 22. In the illustrated embodiment, the spacer 24 is arranged between the pole piece 22 and the winding 4 of the conductor 5. The cooling channel 8 is formed with the help of the spacer 24. In comparison to the two previous embodiments, in this illustrated embodiment of Fig. 7, there is no overmolded shape of the conductor 5, but the basic insulation 23 around the conductor 5 remains. In Fig. 8, the spacer 24 is formed with the help of an insulation layer 26 on the stator tooth 3. The insulation layer 26 begins partially on the surface of the stator tooth 3 and then runs along the contour of the pole piece 22 on the underside of the pole piece 22 towards the outer side 6 of the stator tooth 3 and follows in the radial direction in the direction of gravity downwards along this outer side 6.The spacer 24, which is formed on the insulation layer 26 of the stator tooth 3, is again arranged between the pole piece 22 and the conductor 5. The cooling channel 8 corresponds to the cooling channel 8 from the previous embodiment according to Figs. 6 and 7.

[0047] In Fig. 9, the spacer 24 is again formed on the insulation layer 26 of the stator tooth 3, but with the difference that the spacer 24 is arranged between the turns 4 of the conductor 5. The spacer 24, here a so-called snap-fit, has the shape of a tapered tip. The wound conductor 5 is also secured with this snap-fit ​​and creates a distance between two turns 4 and between the pole piece 22 and turn 4, thereby forming the cooling channel 8.

[0048] In Fig. 10, the embodiment of spacers 24 known from Fig. 9, which are arranged between two turns 4 of the conductor 5, is expanded to a second embodiment in that spacers 24 in the form of the aforementioned snap-fits are arranged between each turn 4 of the conductor 5 and are formed directly on the insulation layer 26 of the stator tooth 3. Thus, the cooling channels from Fig. 9 are expanded by cooling channels 8 between each adjacent turn 4.

[0049] Fig. 11 shows a further embodiment of the spacer 24 already known from Figs. 9 and 10, which is formed solely from the insulation layer 26 of the stator tooth 3. The spacer 24 protrudes axially and is positioned centrally relative to one of the windings 4, in the embodiment shown in the radial direction of the second winding 4 from the top, so that this winding 4 of the conductor 5 protrudes from the ordered shape and is displaced in the axial direction compared to the other windings 4. The spacer 24 has an oblique / inclined edge on both side surfaces, as a result of which the adjacent windings 4 of the displaced winding 4 are also spaced apart from one another in the radial direction. This larger, wider shape of the spacer 24 holds the wound conductor 5 in position. The displacement of the winding 4 forms the cooling channels 8 that run between the windings 4.

[0050] In Fig. 12, the stator tooth 3 is shown with separate pole pieces 22, in the form of edge elements. In the present embodiment, the pole pieces 22 are formed as a separate component from the stator tooth 3. The pole pieces 22 are connected to the stator tooth 3. The stator tooth 3 and the stator yoke 20 are formed as a single piece. The design of the spacers 24 is identical to the design shown in Fig. 6.

[0051] In Fig. 13, the pole shoes 22 are formed by means of a pole shoe plate 27. The pole shoe plate 27 is shaped such that it extends in the axial direction beyond the stator tooth 3, so that the extension projecting outward in the axial direction compared to the stator tooth 3 represents the pole shoe 22.

[0052] In Fig. 14, the spacer 24 is formed on the pole piece 22 according to Fig. 7, and the pole piece is formed according to Fig. 12. In a further embodiment, the spacer 24 can also be formed on the pole piece 22 according to Fig. 13 by the pole piece plate 27. The course of the cooling channel 8 corresponds to the arrangement in Fig. 7.

[0053] In Fig. 15, the spacer 24 is molded onto the stator cover 11, 12. The stator cover 11, 12 is formed around the pole piece 22. To insulate the pole piece 22 using the stator cover 11, 12, the pole piece 22 can be injection-molded into the stator cover 11, 12. The positioning and shape of the spacer 24 corresponds to the spacer 24 shown in Fig. 7.

[0054] In Fig. 16 an embodiment is shown in which the spacer 24 on the

[0055] Stator cover 11 , 12 is designed alone and compared to Fig. 15 the

[0056] Pole shoe 22 is not overmolded by the stator cover 11, 12. The stator cover 11, 12 is designed such that, as in the previous embodiments up to Fig. 14, it not only rests radially above the pole shoes 22, but in this embodiment, the stator cover 11, 12 fills a cavity formed between the pole shoes 22 of two different, adjacent stator teeth 3. The spacer 24 is positioned such that it is positioned towards the outer edge of the windings 4 of the conductor 5. The cooling channel 8 runs between the upper winding 4 and the underside of the pole shoe 22.

[0057] In Fig. 17, the cooling channel 8 is formed by the differently arranged windings 4 of the conductor 5. The conductor 5 is formed with a two-layer winding 4. The inner windings 4 of the conductor 5, offset from the outer windings 4 of the conductor 5, form a small cavity to the pole pieces 22, through which the cooling oil flows along the cooling channel 8.

[0058] In Fig. 18, the cooling is defined by means of the cooling channel 8 formed by cooling grooves 28. The cooling groove 28 is a recess on the pole piece 22, which allows the cooling oil to flow behind the pole piece 22 to the stator teeth 3.

[0059] In Fig. 19, the cooling of the pole pieces 22 is implemented by means of inclined windings 4. The inner part of the windings 4 is positioned against the underside of the pole piece 22. The cooling channel 8 flows from the outside in an axial direction to the inclined inner part of the winding 4.

[0060] Fig. 20 shows the spacer 24 according to a combination of the embodiments from Fig. 15 and Fig. 16. The pole piece 22 is injected into the stator cover 11, 12 and the stator cover 11, 12 fills the cavity formed between the pole pieces 22 of two different, adjacent stator teeth 3. The dimensioning of the spacer 24 is based on Fig. 15. Because, in comparison to Fig. 15, not only the contour of the pole piece 22 is overmolded, but the area is sprayed with material over its entire surface, this area can be used for positioning the spacer 24. Figs. 21 and 22 show a further embodiment for the formation of the cooling channel 8. In Fig. 21, local protrusions 25 are formed in the upper winding 4 of the conductor 5, which are shown in more detail in the side view according to Fig. 22. These protrusions 25 are formed toward the underside of the pole piece 22.The cooling channel 8 thus flows around the pole piece 22. The stator tooth 3 can also be cooled by means of the cooling channel 8.

[0061] List of reference symbols

[0062] 1 stator

[0063] axial flux machine

[0064] 3 stator teeth

[0065] winding

[0066] 5 ladders

[0067] 6 Outside

[0068] 7 remedies

[0069] 8 cooling channel

[0070] 9 left stator half

[0071] 10 right stator half

[0072] 11 left stator cover

[0073] 12 right stator cover

[0074] 13 left housing cover

[0075] 14 right housing cover

[0076] 15 Rotor

[0077] 16 warehouses

[0078] 17 camps

[0079] 18 camps

[0080] 19 spacers

[0081] 20 Stator yoke

[0082] 21 Stator slot

[0083] 22 Pole piece

[0084] 23 Basic insulation

[0085] 24 spacers

[0086] 25 local formation

[0087] 26 Insulation layer of the stator tooth

[0088] 27 Pole shoe plate

[0089] 28 Cooling groove

[0090] A axis of rotation

Claims

Patent claims 1 . Stator (1) for an axial flux machine (2), with a stator tooth (3) which is surrounded by a conductor (5) arranged in windings (4), wherein the windings (4) are arranged on the outer side (6) of the stator tooth (3), characterized in that means (7) are used to keep a cooling channel (8) free between the stator tooth (3) and the winding (4).

2. Stator (1) according to claim 1, characterized in that the means (7) comprise at least one spacer (24) and / or are determined by the arrangement of the windings (4) on the outer side (6) of the stator tooth (3).

3. Stator (1) according to claim 2, characterized in that the spacer (24) is an integral part of the stator tooth (3), a base insulation (23) of the winding, an insulation layer (26) of the stator tooth (3) or a stator cover (11, 12) or the windings are aligned relative to each other and the surface of the stator tooth (3) in such a way that the cooling channel (8) is forced.

4. Stator (1) according to claim 3, characterized in that the spacer (24) projects in the axial direction or radial direction.

5. Stator (1) according to claim 3, characterized in that the windings are arranged obliquely to the radial and axial directions.

6. Stator (1) according to one of claims 3 to 5, characterized in that the spacer (24) runs at least partially between two windings (4) or acts centrally on a winding (4).

7. Stator (1) according to one of claims 3 to 6, characterized in that the spacer (24) acts on several windings (4).

8. Stator (1) according to one of claims 3 to 7, characterized in that at least one spacer (24) is aligned in the axial direction and at least one further spacer (24) is aligned in the radial direction.

9. Stator (1) according to one of claims 3 to 8, characterized in that the winding has local formations (25) for forming at least one of the spacers (24).

10. Axial flux machine (2) with a rotor (15) which cooperates during operation with a stator (1) according to one of the preceding claims.

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