Axial flow machine with stator and optimized pole shoe cooling

Abstract

The invention relates to a stator (1) for an axial flow machine (2), having stator teeth (3) which are surrounded by conductors (5) arranged in the form of windings (4), the windings (4) being arranged on the outer sides (6) of the stator teeth (3), and means (7) being inserted in order to keep a cooling channel (8) unblocked between the stator teeth (3) and the windings (4). The invention also relates to an axial flow machine (2) having a rotor (15) which cooperates with the stator (1) during operation.

Description

TECHNICAL FIELD

[0001] The invention relates to a stator for an axial flow machine, the stator having stator teeth, which are surrounded by conductors arranged in the form of turns, wherein the turns are arranged on the outer side of the stator teeth. BACKGROUND

[0002] In recent years, the demand for axial flow machines has been increasing, mainly due to the advantages in terms of installation space and cost savings presented by their short axial length, but also due to their high efficiency, which allows higher torques and higher power densities to be achieved compared to machines of radial design. The main feature of axial flow machines is the disc-like structure of the stator and the rotor, the number of stators and rotors used varying depending on the structure chosen for the axial flow machine. It is known for stator teeth to be provided on the stator, more precisely on the stator yoke, which are formed, for example, as a laminated core, in order to reduce losses, such as eddy current losses, that accompany heating. On the stator teeth, pole shoes are provided, which allow the magnetic field lines of the conductors wound around the stator teeth to emerge and be distributed to the rotor. Typically, the pole shoes are anchor-shaped. The pole shoes are not enclosed by the field winding. If the stator teeth are enclosed by the winding, the winding is close to the stator teeth and thus also to the pole shoes. Since the winding fits very closely against the stator teeth, cooling is required in order to reduce heating and further minimise losses that accompany heating. SUMMARY

[0003] The object of the invention is to eliminate or at least partially mitigate the mentioned disadvantages. The focus is on improving the cooling of the pole shoes.

[0004] This is achieved for a stator of the above-mentioned type for an axial flow machine by using means to keep the cooling channel between the stator teeth and the turns clear. In order to form a cooling channel between the stator teeth and the turns, at least a space needs to be formed between the stator teeth and the turns. This space can then be used to direct cooling fluid to the pole shoes via a cooling oil supply.

[0005] Advantageous embodiments are claimed in the dependent claims and explained in more detail below.

[0006] Furthermore, the device can comprise at least one distance piece and / or be determined by the arrangement of the turns on the outer side of the stator teeth. Thus, there are various options for implementing the cooling channel. The distance piece provides an additional element in the assembly, which forms a space between the turns and the stator teeth. According to the embodiment, the distance piece can be fastened to the individual elements of the stator. The arrangement of the turns provides another solution, which eliminates the need for additional elements, thus avoiding the redesign of existing elements. In order to design the space between the turns and the stator teeth particularly reliably, both solutions involving the distance piece and the arrangement of the turns can be combined. This allows a flexible design depending on the application.

[0007] In addition, the distance piece can be an integral part of the stator tooth, the basic insulation of the winding, the insulation layer of the stator tooth or the stator cover, or the windings can be aligned to each other and to the surface of the stator tooth such that the cooling channel is reinforced. If the distance piece is provided as an integral part of the stator tooth, then the distance piece is then formed directly on the pole shoe, for example, during the manufacturing process of the pole shoe. The distance piece is preferably implemented in the form of a protruding part. In cross section, the geometry of the protruding part is, for example, rectangular, semicircular or tapered. The height of the distance piece must be designed according to the required cooling oil flow, which defines the dimensions of the cooling channel, for example, the length of the cooling channel in the radial direction, etc. Thus, the gap between the stator tooth and the winding can be larger or smaller. If the distance piece is provided on the basic insulation of the winding, it is formed directly by the overmolding of the wound conductor produced by the production of the basic insulation. If an additional insulation is provided on the stator tooth, for example, as a result of the slot insulation, the insulation layer can be directly implemented with the distance piece. Likewise, the distance piece can be directly provided on the stator cover, wherein the distance piece is likewise provided directly on the stator cover during the manufacturing process of the stator cover. If the space between the turns and the stator teeth is implemented without a physical distance piece, then this space is then implemented by the mutual positioning of the windings and the positioning of the windings with respect to the surface of the stator teeth. Depending on the winding type, for example, whether it is a single-layer winding or a double-layer winding, different arrangements can be implemented.

[0008] Advantageously, the distance piece projects in axial direction and / or in radial direction. According to the embodiment, a combination of distance pieces or a plurality of distance pieces in axial direction and radial direction is possible. If the distance piece is preferably embodied as an integral part of the stator tooth in the form of a protrusion, the distance piece is positioned on the side facing the winding in radial direction. If the distance piece is provided on the stator cover, the distance piece then has a protrusion on the stator tooth comparable to the above-mentioned embodiment. In the case of the embodiment where the distance piece is an integral part of the basic insulation of the winding, a combination of axial direction and radial direction can be realized, for example. In order to position the winding between the stator yoke and the pole shoe and to provide a cooling channel, the distance piece formed on the basic insulation is arranged between the basic insulation and the lower side of the pole shoe and between the top side of the stator yoke and the basic insulation. In order to space the winding relative to the outer side of the stator tooth, a further distance piece is provided on the basic insulation in axial direction, which distances the winding comprising the basic insulation from the stator tooth. Advantageously, at least two distance pieces are provided in axial direction to ensure a stable arrangement.

[0009] Advantageously, the winding is arranged inclined relative to the radial direction and the axial direction. In the case of a simple winding (single layer), the winding is inclined in a way that is inclined relative to the lower side of the pole shoe, thus intensifying the cooling channel. In the case of a double winding (double layer), the two layers of the winding can be positioned differently from one another. For example, the inner winding can be offset relative to the outer winding, thus forming a cavity on the pole shoe that can be used as a cooling channel. Omitting an element in the form of a distance piece as a means of keeping the cooling channel free means that one wear part is less.

[0010] Furthermore advantageously, the distance piece extends at least partially between two turns or acts centrally on one turn. If the distance piece is arranged in axial direction, the distance piece can be formed such that it forms a space between the turns. In one advantageous embodiment, one or more distance pieces are formed on the insulation layer on the stator tooth. Depending on the application, the distance piece has different shapes that act on one turn or extend between two turns. With a first distance piece, a space can be formed between two turns, preferably between a turn oriented toward the lower side of the pole shoe and the turn adjacent thereto. A further distance piece can be positioned between further turns. Preferably, the distance piece has a tapered shape, for example a tip, such that the conductor with the turn is more easily attached and fixed and thus a cooling channel is provided. In a further embodiment, the distance piece acts centrally on the turn such that the turn projects in axial direction beyond the other turns and the cooling channel is exposed.

[0011] Furthermore, the distance pieces can act on multiple turns. If the distance pieces are embodied such that they centrally act on one turn, the respective neighboring turns can be spaced apart in the radial direction from this one turn by the shape of the distance pieces. If the side surfaces of the distance pieces are beveled / oblique, this leads to a displacement of the neighboring turns and a displacement of the positioning of the winding between the pole shoes and the stator yoke.

[0012] Advantageously, at least one distance piece is oriented in the axial direction and at least one further distance piece is oriented in the radial direction. The above embodiments for providing cooling channels using the device can be combined with one another.

[0013] In addition, the winding can have a locally shaped portion for providing at least one of the distance pieces. The locally shaped portion is formed here on a turn of the conductor winding which is oriented toward the lower side of the pole shoe. The locally shaped portion is provided in the lateral direction along the turn such that the turn forms a wave-shaped profile, for example, which provides the cooling channel. Omitting an element in the form of a molded distance piece as a means for keeping the cooling channel open means one less wearing part.

[0014] In a further advantageous embodiment, the pole shoes are elements separate from the stator teeth. In this case, the pole shoes can be connected individually to the stator teeth in the form of edge elements or in the form of pole shoe plates, wherein the edge elements and the pole shoe plates are dimensioned such that they in each case protrude beyond the stator teeth in both directions in the axial direction in order to reproduce the form of an anchor in combination with the stator teeth. If the stator teeth and the pole shoes are elements separate from one another, the pole shoes can be injected into the stator cover, for example, thereby simplifying the arrangement with respect to the stator teeth.

[0015] In addition, cooling channels in the form of cooling grooves can be formed in the pole shoes. These cooling channels are recesses in the pole shoes which allow cooling oil to flow from behind the pole shoes to the stator teeth. If the stator teeth are made of a stack of electrical steel sheets, these channels can be formed by selectively punching out several adjoining sheet layers.

[0016] The invention also relates to a axial flow machine having a rotor which cooperates with a stator during operation. BRIEF DESCRIPTION OF DRAWINGS

[0017] Various advantageous embodiments of the invention are explained in greater detail below with reference to the figures comprising drawings.

[0018] In the drawings:

[0019] Figure 1 An axial flow machine having a stator according to the invention is shown,

[0020] Figure 2 is shown Figure 1The stator half of the stator according to the invention,

[0021] Figure 3 shows a stator half comprising windings around individual stator teeth,

[0022] Figure 4 is a cross-sectional view of an individual stator tooth with overmolded windings,

[0023] Figure 5 is based on Figure 4 Detailed view of the cooling channel with the aid of a distance element,

[0024] Figure 6 Shown according to Figure 4 stator teeth with overmolded double-layer windings,

[0025] Figure 7 shows the distance elements arranged on the pole shoes of the stator teeth,

[0026] Figure 8 shows the distance elements arranged in the radial direction on the insulation layer of the stator teeth,

[0027] Figure 9 A distance piece is shown which is arranged on the insulation layer of a stator tooth and between two turns.

[0028] Figure 10 A plurality of distance elements are shown which are arranged in the axial direction on the insulation layer of the stator teeth and between the turns.

[0029] Figure 11 A distance element is shown which is arranged on the insulation layer of the stator tooth and acts centrally on the turns,

[0030] Figure 12 Shown according to Figure 6 stator teeth with separate pole shoes in the form of edge elements with cooling channels,

[0031] Figure 13 Shown according to Figure 6 stator teeth with separate pole shoes in the form of pole shoe plates with cooling channels,

[0032] Figure 14 shows the distance elements on the pole shoe edge or pole shoe plate,

[0033] Figure 15 A first embodiment of a distance element arranged on a stator cover with injected pole shoes is shown,

[0034] Figure 16 shows a distance element arranged on a stator cover with a filled cavity,

[0035] Figure 17 A double-layer winding with biasing outer turns applied against the pole shoe is shown,

[0036] Figure 18 Cooling of the pole shoe by cooling slots in the pole shoe is shown,

[0037] Figure 19 Cooling of the pole shoe by slightly inclined turns is shown,

[0038] Figure 20 A second embodiment of a distance piece arranged on a stator cover with injection pole shoes is shown,

[0039] Figure 21 Cooling channels provided by locally shaped sections in the turns are shown,

[0040] Figure 22 is a side view of a cooling channel according to Figure 21 The drawings are essentially schematic and are merely intended to aid in the understanding of the present application. Identical elements are provided with identical reference signs. Features of the various embodiments can be interchanged and used as alternatives / accumulations.

[0041] DETAILED DESCRIPTION

[0042] A stator 1 for an axial flow machine 2 according to the present application is shown, Figure 1 A complete assembly of the axial flow machine 2 is shown. The stator 1 has stator teeth 3 which are surrounded by conductors 5 arranged in the form of turns 4, wherein the turns 4 are arranged on the outer side 6 of the stator teeth 3. A device 7 (shown in Figure 1 The cooling channels 8 (shown starting from Figure 4 between the stator teeth 3 and the turns 4 are kept free using a device 7 (shown in the drawings). The stator 1 is arranged along a rotation axis A. The stator 1 has two stator halves 9, 10, namely 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 turns 4. In each case, the stator halves 9, 10 are surrounded by stator covers 11, 12 and housing covers 13, 14, to which 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. In the radially outer region, a spacer 19 is arranged between the housing covers 13, 14. Figure 5

[0043] Figure 2 ​The structure of the stator halves 9, 10 of the stator 1 is then shown. The stator halves 9, 10 have a stator yoke 20 on which the individual stator teeth 3 are arranged in a circumferential direction. Between the individual stator teeth 3 there is provided a slot 21, so that the space between the individual stator teeth 3 is kept clear for the winding of the conductor 5 into the turns 4.

[0044] In Figure 3 , from Figure 2 the known stator halves 9, 10, the conductor 5 is arranged which is wound with turns 4 on the stator teeth 3. In addition, each stator tooth 3 now has a pole shoe 22. The pole shoe 22 rests on the upper surface of the respective stator tooth 3 and delimits the winding.

[0045] Figure 4 A sectional view of an individual stator tooth 3 is shown. In the embodiment shown, the conductor 5 and its turns 4 are shown in the form of an overmolding. This overmolding provides the conductor 5 with a basic insulation 23. Then, a device 7 in the form of a distance piece 24 is provided on this basic insulation 23. In the present embodiment, the distance pieces 24 are provided on the basic insulation 23 in the radial direction and in the axial direction. The distance pieces 24 in the radial direction each form a protrusion on the basic insulation 23 between the wound conductor 5 and the lower side of the pole shoe 22, and on the other side between the wound conductor 5 and the top side of the stator yoke 20. The distance pieces 24 in the axial direction form on the basic 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.

[0046] In Figure 5 , the arrangement from Figure 4 the known is shown in a detailed illustration with respect to the distance pieces 24 embodied as the device 7. The distance pieces 24 enable an optimized supply of cooling oil via the cooling channel 8. The path of the cooling channel 8 extends in the axial direction between the lower side of the pole shoe 22 and the opposite turns 4 of the wound conductor 5 to the outer side 6 of the stator tooth 3 and then along this outer side 6 in the radial direction from top to bottom in the direction of gravity.

[0047] Figure 6 A further embodiment of the arrangement from Figure 4 the known is shown, in which the distance pieces 24 serve as the device 7. The second embodiment shows the conductor 5 in a double winding. The double winding of the conductor 5 is characterized in that the winding is two layers in the axial direction. The design of the distance pieces 24 corresponds to the design of the distance pieces shown in Figure 4 .

[0048] In Figure 7In the embodiment shown, the distance piece 24 is formed directly on the lower side of the pole shoe 22. In the embodiment shown, the distance piece 24 is arranged between the pole shoe 22 and the turns 4 of the conductor 5. The cooling channel 8 is formed by means of the distance piece 24. Compared with the previous two embodiments, in Figure 7 In the embodiment shown in FIG, the conductor 5 is not present in overmolded form, but the primary insulation 23 still remains around the conductor 5 .

[0049] exist Figure 8 In the embodiment, the distance piece 24 is formed on the stator tooth 3 by means of an insulating layer 26. The insulating layer 26 partially starts at the surface of the stator tooth 3 and then extends along the contour of the pole shoe 22 on the lower side of the pole shoe 22 toward the outer side 6 of the stator tooth 3, and then extends radially downward along the outer side 6 in the direction of gravity. The distance piece 24 formed on the insulating layer 26 of the stator tooth 3 is again arranged between the pole shoe 22 and the conductor 5. The cooling channel 8 corresponds to the Figure 6 and Figure 7 The cooling channel 8 of the previous embodiment.

[0050] exist Figure 9 In FIG, the distance pieces 24 are again formed on the insulation layer 26 of the stator teeth 3, but the difference is that the distance pieces 24 are arranged between the turns 4 of the conductor 5. The distance pieces 24 here take the shape of a tapered tip to provide a "snap fit." The wound conductor 5 is also fixed using this snap fit, and a space is formed between the two turns 4 and between the pole piece 22 and the turns 4, thereby forming the cooling channel 8.

[0051] exist Figure 10 In the embodiment, the distance piece 24 is arranged between each turn 4 of the conductor 5 in the form of the above-mentioned snap fit and is formed directly on the insulating layer 26 of the stator tooth 3. Figure 9 The known embodiment of the distance element 24 arranged between two turns 4 of the conductor 5 is expanded to a second embodiment. Figure 9 The cooling channel is extended by the cooling channel 8 between each adjacent turn 4.

[0052] Figure 11 Shows that it has been Figure 9 and Figure 10Another embodiment of the distance piece 24 is known, which is formed only by the insulation layer 26 of the stator tooth 3. In the embodiment shown in the radial direction from the top along the second turn 4, the distance piece 24 protrudes axially and is positioned centrally with respect to one of the turns 4, so that this turn 4 of the conductor 5 protrudes from the ordered shape and is axially displaced with respect to the other turns 4. The distance piece 24 has beveled / angled chamfers at both side surfaces, whereby the adjacent turns 4 of the displaced turn 4 are also spaced apart from each other in the radial direction. This larger, wider shape of the distance piece 24 keeps the wound conductor 5 in place. By displacing the winding 4, a cooling channel 8 is formed which extends between the windings 4.

[0053] In Figure 12 , the stator tooth 3 is shown with a separate pole shoe 22 in the form of an edge element. In this embodiment, the pole shoe 22 is formed as a separate part from the stator tooth 3. The pole shoe 22 is connected to the stator tooth 3. The stator tooth 3 and the stator yoke part 20 are implemented together as one piece. The embodiment of the distance piece 24 is the same as in Figure 6 .

[0054] In Figure 13 , the pole shoe 22 is formed by way of a pole shoe plate 27. The pole shoe plate 27 is formed such that it extends in the axial direction beyond the stator tooth 3, so that the extension protruding in the axial direction with respect to the stator tooth 3 represents the pole shoe 22.

[0055] In Figure 14 , the distance piece 24 is formed on the pole shoe 22 according to Figure 7 , and the pole shoe is provided according to Figure 12 . In another embodiment, the distance piece 24 can also be formed from the pole shoe plate 27 on the pole shoe 22 according to Figure 13 . The route of the cooling channel 8 corresponds to the arrangement according to Figure 7 .

[0056] In Figure 15 , the distance piece 24 is formed on the stator cover 11, 12. The stator cover 11, 12 is arranged around the pole shoe 22. In order to insulate the pole shoe 22 by means of the stator cover 11, 12, the pole shoe 22 can be injected into the stator cover 11, 12. The positioning and shape of the distance piece 24 correspond to the distance piece 24 according to Figure 7 .

[0057] Figure 16 An embodiment is shown in which the distance piece 24 is implemented separately on the stator cover 11, 12, and in contrast to Figure 15 , the pole shoe 22 is not overmolded by the stator cover 11, 12. The stator cover 11, 12 is implemented such that, as in up to Figure 14In the previous embodiments of the stator cover, the stator cover rests not only radially above the pole shoes 22, but in this embodiment the stator cover 11, 12 fills the cavity formed between the pole shoes 22 of two different adjacent stator teeth 3. The distance piece 24 is positioned such that it is positioned towards the outer edge of the turns 4 of the conductor 5. The cooling channel 8 extends between the upper turns 4 and the lower side of the pole shoes 22.

[0058] In Figure 17 , the cooling channel 8 is formed by means of differently arranged turns 4 of the conductor 5. The conductor 5 is provided with double-layered turns 4. The inner turns 4 of the conductor 5 form small cavities to the pole shoes 22 by means of an offset with respect to the outer windings 4 of the conductor 5, through which the cooling oil flows along the cooling channel 8.

[0059] In Figure 18 , the cooling is defined by a cooling channel 8 formed by a cooling groove 28. The cooling groove 28 is a recess in the pole shoe 22 which allows the cooling oil to flow from behind the pole shoe 22 to the stator tooth 3.

[0060] In Figure 19 , the cooling of the pole shoe 22 is achieved by means of obliquely positioned turns 4. The inner part of the turns 4 is in contact with the lower side of the pole shoe 22. The cooling channel 8 flows in the axial direction from the outside to the inside up to the oblique inner part of the turns 4.

[0061] In Figure 20 , a distance piece 24 according to a combination of the embodiments of Figure 15 and Figure 16 is shown. The pole shoe 22 is here injected into the stator cover 11, 12 and the stator cover 11, 12 fills the cavity formed between the pole shoes 22 of two different adjacent stator teeth 3. The distance piece 24 is dimensioned based on Figure 15 . Since the contour of the pole shoe 22 is not only overmoulded but the entire area is filled with injection material compared to Figure 15 , this area can be used to position the distance piece 24.

[0062] Figure 21 and Figure 22 another embodiment for forming a cooling channel 8 is shown. In Figure 21 , in the upper turns 4 of the conductor 5, locally shaped parts 25 are formed, which are shown in more detail in the side view according to Figure 22 . These shaped parts 25 are formed towards the lower side of the pole shoe 22. Thus, the cooling channel 8 flows around the pole shoe 22. The stator tooth 3 can likewise be cooled via the cooling channel 8.

[0063] List of reference signs

[0064] 1 stator

[0065] 2 axial flow machine

[0066] 3 stator tooth

[0067] 4 turns

[0068] 5 conductors

[0069] 6 outer side

[0070] 7 device

[0071] 8 cooling channel

[0072] 9 left stator half

[0073] 10 right stator half

[0074] 11 left stator cover

[0075] 12 right stator cover

[0076] 13 left housing cover

[0077] 14 right housing cover

[0078] 15 rotor

[0079] 16 bearing

[0080] 17 bearing

[0081] 18 bearing

[0082] 19 spacer

[0083] 20 stator yoke

[0084] 21 stator slot

[0085] 22 pole shoe

[0086] 23 basic insulation

[0087] 24 distance piece

[0088] 25 locally shaped portion

[0089] 26 insulation layer of stator tooth

[0090] 27 pole shoe plate

[0091] 28 cooling slot

[0092] A axis of rotation

Claims

1. A stator (1) for an axial flow machine (2), the stator having stator teeth (3) which are encircled by conductors (5) arranged in the form of turns (4), wherein, The turns (4) are arranged on the outer side (6) of the stator tooth (3), characterized in that means (7) are used to keep the cooling channel (8) between the stator tooth (3) and the turns (4) open.

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

3. Stator (1) according to claim 2, characterized in that The distance piece (24) is an integral part of the stator tooth (3), of a basic insulation piece (23) of the winding, of an insulation layer (26) of the stator tooth (3) or of a stator cover (11, 12), or the windings are aligned to one another and to the surface of the stator tooth (3) in such a way that the cooling channel (8) is reinforced.

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

5. Stator (1) according to claim 3, characterized in that The winding is arranged in an inclined manner with respect to the radial direction and the axial direction.

6. Stator (1) according to one of claims 3 to 5, characterized in that The distance piece (24) extends at least partially between two turns (4) or acts centrally on one turn (4).

7. A stator (1) according to any one of claims 3 to 6, characterized in that The distance piece (24) acts on a plurality of turns (4).

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

9. Stator (1) according to one of claims 3 to 8, characterized in that The winding has a locally shaped portion (25) for providing at least one of the distance pieces (24).

10. A axial flow machine (2) having a rotor (15) which cooperates during operation with a stator (1) according to one of the preceding claims.

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