Electric machine

Abstract

The invention relates to an electric machine (1) comprising a stator (2) and a rotor (3) which can be rotated relative to the stator (2) about an axis of rotation (4) that defines an axial direction, wherein the rotor (3) comprises a laminated core (5) on which a plurality of pole shoes (6) are formed which carry a rotor winding (7), wherein an electrically insulating insulation layer (8) is arranged between the rotor winding (7) and each pole shoe (6), wherein at least one axially extending cooling channel (11, 12) for conducting a coolant is formed at each pole shoe (6) between the rotor winding (7) and the pole shoe (6), the cooling channel having a channel wall (13) which delimits the cooling channel (11, 12) transversely with respect to the axial direction. A simplified construction is achieved if the insulation layer (8) and the channel wall (13) consist of an electrically insulating plastic which is integrally formed on each pole shoe (6) by overmoulding or casting.

Description

[0001] Electric machine

[0002] The present invention relates to an electrical machine according to the preamble of claim 1.

[0003] An example of a generic electrical machine is made from the

[0004] DE 102021 103441 A1 is known and comprises a stator and a rotor, which is rotatable about an axis of rotation relative to the stator, defining an axial direction. The rotor has a laminated core on which several pole shoes are formed, each supporting a rotor winding. An electrically insulating inflation layer is arranged between the rotor winding and the respective pole shoe. Furthermore, at least one axially extending cooling channel for conveying a coolant is formed on each pole shoe between the rotor winding and the respective insulation layer. This cooling channel has a channel wall that limits the cooling channel transversely to the axial direction. In the known machine, the respective cooling channel is formed by means of a separate tube body, which is placed on the respective insulation layer before the rotor winding is attached. The manufacturing effort for such a machine is comparatively high.

[0005] From DE 102017213960 A1 another electric machine is known in which cooling channels in the form of separate tubes are placed on the rotor winding and are positioned on the rotor winding by means of a locking wedge which is supported on two circumferentially adjacent pole shoes.

[0006] From DE 19964061 A1, an electric motor is known in which an electrically insulating insulating layer and end lamellae, each covering an axial end face of the lamination stack, are injection-molded from plastic in a single injection process.

[0007] From DE 202017006523 U1 and from EP 3871 323 B1, an electrical machine is known in which the electrically insulating insulating layer is sprayed on, for which spray channels are formed in the sheet metal stack to guide the insulating material during the spraying process.

[0008] The present invention addresses the problem of providing an improved or at least a different embodiment of an electric machine of the type described above, which is characterized in particular by reduced manufacturing costs, and also by improved cooling of the rotor.

[0009] This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0010] The invention is based on the general concept of forming at least one axially extending cooling channel for guiding a coolant on a pole shoe between the rotor winding and the respective pole shoe, by injection-molding a channel wall, which defines the cooling channel transversely to the axial direction, onto the respective pole shoe. This makes it possible, in particular, to produce the insulation layers and the cooling channels using a single injection molding process. For forming the respective channel wall, extendable cores or slides can be used in a suitable molding tool, especially an injection mold. Cores that dissolve after the injection molding process can also be used. Furthermore, tubular cores can be used that remain on the respective pole shoe after the injection molding process and support the injection-molded plastic channel wall there.

[0011] Specifically, it is proposed that the respective insulation layer and channel wall consist of an electrically insulating material, in particular plastic, which is injection-molded onto the respective pole shoe. The injection-molded insulation layer has good thermal conductivity, which improves heat transfer between the laminated core and the rotor winding.

[0012] The electrical machine is appropriately an electrically excited synchronous machine.

[0013] According to an advantageous embodiment, the spraying process can be configured such that the respective channel wall and the respective insulation layer have a common insulation section that, on the one hand, delimits the respective cooling channel transversely to the axial direction and, on the other hand, abuts the respective pole shoe transversely to the axial direction. In other words, a circumferential section of the respective channel wall is directly formed by the insulation layer. In this way, the heat transfer between the insulation layer and the coolant is improved.

[0014] In the present context, a “configuration” corresponds to a “design” and / or a “setup”, so that the phrase “configured so that” is synonymous with the phrase “designed so that” and / or “set up so that”.

[0015] According to an advantageous embodiment, each pole shoe can have two pole shoe sides facing away from each other in the circumferential direction. Advantageously, at least one such cooling channel can be formed on at least one, preferably on both, pole shoe sides. In this way, two cooling channels can be accommodated between two adjacent pole shoes in the circumferential direction, thereby significantly improving the cooling performance.

[0016] According to an advantageous embodiment, one of the two cooling channels located on one side of the respective pole shoe can be arranged radially offset from the other cooling channel located on the opposite side of the pole shoe. This results in improved heat dissipation from the respective pole shoe.

[0017] In another embodiment, a winding support can be formed at one axial end of each pole shoe, carrying a section of a rotor winding head associated with that pole shoe. The winding support can have at least one groove structure on its outer surface, facing axially away from the pole shoe, which fluidically connects at least one of the cooling channels to a coolant connection for supplying or removing the coolant. This allows for direct cooling in the area of ​​the winding head. Furthermore, it provides a simple supply and removal of the coolant to and from the cooling channels.

[0018] In an advantageous embodiment, the groove structure on the outside of each winding support can fluidically connect the two cooling channels of the respective pole shoe to the single coolant connection for supplying or removing the coolant. According to a suitable configuration, the coolant connection on each winding support can be located centrally in the circumferential direction. Furthermore, the respective coolant connection can be arranged radially inwards on the respective winding support. Additionally or alternatively, the rotor in the laminated core can have a central cooling channel that is fluidically connected to the coolant connection and can serve as a supply channel for supplying coolant to the respective cooling channel or as a discharge channel for removing coolant from the respective cooling channel.

[0019] According to another advantageous embodiment, the respective winding support can be made of an electrically insulating plastic that is injection-molded onto the respective pole shoe. This allows the respective winding support to be attached to the rotor in a particularly cost-effective and simple manner.

[0020] In a preferred embodiment, the insulating layer, the respective channel wall and / or the respective winding carrier can contain an electrically insulating polymer, preferably a thermosetting plastic, in particular an epoxy molding compound, which is molded onto the respective pole shoe.

[0021] A particularly advantageous embodiment is one in which the respective insulating layer, the respective channel wall, and the respective winding support consist of the same electrically insulating plastic that is injection-molded onto the respective pole shoe. In particular, this makes it possible to form the respective insulating layer, the respective channel wall, and the respective winding support on the respective pole shoe in a single injection molding process.

[0022] According to another advantageous embodiment, the slot structure of the respective winding carrier can be axially covered and closed by the rotor winding. This means that the rotor winding in the area of ​​the slot structure is directly exposed to the coolant, which improves heat dissipation.

[0023] Advantageously, the rotor winding can be configured such that at least one cavity is formed on the respective winding support between the rotor winding, the respective cooling channel, and the slot structure, and this cavity is fluidically connected to the slot structure. Within this cavity, the rotor winding comes into direct contact with the coolant, thus enabling large-area and therefore particularly efficient heat transfer.

[0024] In another advantageous embodiment, the rotor winding can be configured in multiple layers and have at least [number] winding layers that wrap around the respective pole shoe. A first winding layer can rest directly on the respective winding carrier, axially covering the slot structure on the respective winding carrier and extending outside the respective cooling channel. A second winding layer can rest directly on the first winding layer and axially covering the slot structure on the respective winding carrier, also extending outside the respective cooling channel. A third winding layer can rest directly on the second winding layer and axially covering the slot structure and the respective cooling channel on the respective winding carrier.This means that the respective cooling channel is expediently dimensioned in the circumferential direction to accommodate two winding layers, such that the first and second winding layers run radially alongside the respective cooling channel, while the third winding layer and any subsequent winding layers radially overlap the respective cooling channel and thus cover it circumferentially. In one embodiment, a fourth winding layer can be provided, which rests directly on the third winding layer and axially covers the slot structure and the respective cooling channel on the respective winding carrier. Optionally, a fifth winding layer can also be provided, which rests directly on the fourth winding layer and axially covers the slot structure and the respective cooling channel on the respective winding carrier. In particular, an embodiment can be provided in which the rotor winding has exactly five winding layers.

[0025] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0026] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. Components of a higher-level unit, such as a device, apparatus, or arrangement, mentioned above and those to be mentioned below, which are designated separately, can form separate parts or components of this unit or integral areas or sections.

[0027] These are sections of this unit, even if this is shown differently in the drawings.

[0028] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0029] They show, schematically,

[0030] Figures 1 to 5 each show a simplified cross-section of an electric machine in the area of ​​a pole shoe in different cutting planes or at different manufacturing states, Figure 6 shows a simplified longitudinal section of the electric machine corresponding to a section line VI in Figure 5.

[0031] As shown in Figures 1 to 6, an electric machine 1 comprises a stator 2 (indicated only in Figure 6) and a rotor 3, which is rotatable about an axis of rotation 4 relative to the stator 2. The position of the axis of rotation 4 shown in Figures 1 to 6 is not to scale; in particular, the axis of rotation 4 does not lie in the plane of section in Figure 6. The axis of rotation 4 defines an axial direction, a radial direction, and a circumferential direction. The axial direction runs parallel to the axis of rotation 4. The radial direction extends transversely to the axial direction and is, in particular, perpendicular to the axis of rotation 4. The circumferential direction revolves around the axis of rotation 4.

[0032] The rotor 3 has a laminated core 5 on which several pole shoes 6 are formed, distributed around the circumference and supporting a rotor winding 7. In Figures 1 to 5, only one of these pole shoes 6 is shown in each figure, representing all pole shoes 6. The other pole shoes 6, not shown, are expediently designed identically to the pole shoe 6 shown in Figures 1 to 5.

[0033] An electrically insulating layer 8 is arranged between each pole shoe 6 and the rotor winding 7, bearing against the respective pole shoe 6. The pole shoe 6 shown here has a radially extending shaft 9 and a cap 10, which connects radially to the shaft 9 and overlaps the shaft 9 circumferentially. The insulating layer 8 rests against the shaft 9 circumferentially and against the cap 10 radially on the inside. Accordingly, the rotor winding 7 is supported against the shaft 9 and the cap 9, respectively, via the insulating layer 8.

[0034] At each pole shoe 6, at least one axially extending cooling channel 11, 12 is formed between the rotor winding 7 and the respective insulation layer 8. This cooling channel is designed to guide a liquid or gaseous coolant. Each cooling channel 11, 12 has a channel wall 13 that borders the cooling channel 11, 12 transversely to the axial direction. In the machine 1 presented here, the respective insulation layer 8 and the respective channel wall 13 are made of an electrically insulating plastic that is injection-molded onto the respective pole shoe 6. Specifically, the respective insulation layer 8 and the respective channel wall 13 are formed or injection-molded onto the respective pole shoe 6 by means of a single forming process, such as injection molding or compression molding.

[0035] As shown in Figure 1, the respective channel wall 13 and the respective insulation layer 8 have a common insulation section 14, which on one side bounds the respective cooling channel 11, 12 transversely to the axial direction, here in the circumferential direction, and on the other side abuts the respective pole shoe 6, here the shaft 9, transversely to the axial direction, here in the circumferential direction. Thus, the insulation section 14 forms on the one hand a component of the respective insulation layer 8 and on the other hand a component of the respective channel wall 13.

[0036] Each pole shoe 6 has, particularly on the shaft 9, two pole shoe sides 15, 16, which face away from each other in the circumferential direction. Two cooling channels 11, 12 are formed on each pole shoe 6, with one or the first cooling channel 11 being arranged on the first pole shoe side 15, while the other or second cooling channel 12 is arranged on the other or second pole shoe side 16. The preferred configuration is the one shown here, in which the two cooling channels 11, 12 are arranged radially offset from each other on the pole shoe 6 or on its shaft 9. In the example of Figure 1, the first cooling channel 11 shown on the right is arranged radially further inwards, i.e., closer to the axis of rotation 4, on the first pole shoe side 15, than the second cooling channel 12 shown on the left, which is arranged on the second pole shoe side 16. The radial offset is advantageously at least as large as one radial channel width of the respective cooling channel 11, 12.In the example of Figure 1, the radial offset is exactly as large as the radial width of the respective cooling channel 11, 12.

[0037] As shown in Figures 2 to 6, a winding support 17 is arranged or formed at one axial end of each pole shoe 6. In Figures 2 to 5, the winding support 17 covers the associated pole shoe 6, so that the pole shoe 6 and the laminated core are indicated only by a broken reference line in Figures 2 to 5. Each winding support 17 carries a section of a winding head 18 of the rotor winding 7 associated with the respective pole shoe 6, which is only partially visible or only partially formed in Figures 3 to 5. According to Figures 2 to 6, the respective winding carrier 17 has at least one groove structure 19 on an outer side facing axially away from the respective pole shoe 6, which in Figures 2 to 5 is facing the viewer, which connects at least one of the cooling channels 11, 12 of the respective pole shoe 6 to a coolant connection 20, which serves to supply or remove the coolant.The groove structure 19 on the outside of each winding carrier 17 conveniently connects both cooling channels 11, 12 to the coolant connection 20, which serves as a common coolant connection 20. In the example shown, the coolant connection 20 is located centrally on each winding carrier 17 with respect to its circumference. Furthermore, the coolant connection 20 is arranged radially inwards. The rotor 3 can have a coolant channel 21 in the laminated core 5, which is configured as a supply channel for supplying the coolant or as a discharge channel for removing the coolant and which is fluidically connected to the respective coolant connection 20 in a suitable manner.

[0038] Advantageously, each winding carrier 17 consists of an electrically insulating plastic, which is molded onto the respective pole shoe 6 by overmolding. A particularly advantageous configuration is one in which the insulating layers 8, the channel walls 13, and the winding carriers 17 consist of the same electrically insulating plastic and are formed or injection-molded onto the pole shoes 6 in a single molding process, such as an injection molding process.

[0039] As can be seen particularly from Figures 3 to 6, the slot structure 19 of the respective winding carrier 17 can be axially covered and closed by the rotor winding 7. The rotor winding 7 can be configured according to Figure 6 such that at least one cavity 22 is formed in the respective winding carrier 17 between the rotor winding 7, the respective cooling channel 11, 12, and the slot structure 19, and this cavity is fluidically connected to the slot structure 19. For this purpose, the rotor winding 7 can be configured in multiple layers and have at least three winding layers 23. In the example shown here, the rotor winding 7 has exactly five winding layers 23, which wrap around the respective pole shoe 6 as follows.

[0040] A first winding layer 23.1 lies directly on the respective winding carrier 17 axially, as shown in Figure 3, and covers the slot structure 19 on the winding carrier 17, extending in an axial projection of the respective cooling channel 11, 12 outside the respective cooling channel 11, 12. Figure 3 shows the first winding layer 23.1 on the winding carrier 17.

[0041] A second winding layer 23.2 lies directly on top of the first winding layer 23.1 axially, as shown in Fig. 4, and axially covers the slot structure 19 on the respective winding carrier 17. In an axial projection of the respective cooling channels 11, 12, it also extends outside the cooling channels 11, 12. Figure 4 shows the second winding layer 23.2 wound congruently onto the first winding layer 23.1.

[0042] As shown in Figure 5, a third winding layer 23.3 can now rest axially directly on the second winding layer 23.2 and axially cover the slot structure 19 and also the cooling channels 11, 12 on the respective winding carrier 17. This creates the cavities 22 between the rotor winding 7 and the respective winding carrier 17, which are fluidically connected to the slot structure 19.

[0043] A fourth winding layer 23.4, indicated in Figure 1, now rests axially directly on the third winding layer 23.3 and axially covers the slot structure 19 and the cooling channels 11, 12 on the respective winding carrier 17. The same applies to a fifth winding layer 23.5, also indicated in Figure 1, which rests axially directly on the fourth winding layer 23.4 and axially covers the slot structure 19 and the two cooling channels 11, 12 on the respective winding carrier 17. The fourth winding layer 23.4 and the fifth winding layer 23.5 are indicated only outside the winding carrier 17 in Figures 1 to 5. List of reference numerals

[0044] machine

[0045] stator

[0046] rotor

[0047] axis of rotation

[0048] Sheet metal package

[0049] Polschuh

[0050] Rotor winding

[0051] Insulation layer

[0052] shaft

[0053] cap

[0054] Cooling channel

[0055] Cooling channel

[0056] canal wall

[0057] Insulation section

[0058] Pole shoe side

[0059] Pole shoe side

[0060] winding carrier

[0061] winding head

[0062] Grooved structure

[0063] Coolant connection

[0064] Coolant channel

[0065] cavity

[0066] winding position

Claims

Patent claims 1. Electric machine (1 ), - with a stator (2), - with a rotor (3) that is rotatable about a rotational axis (4) relative to the stator (2) which defines an axial direction, - wherein the rotor (3) has a laminated core (5) on which several pole shoes (6) are formed, which carry a rotor winding (7), - wherein an electrically insulating insulating layer (8) is arranged between the rotor winding (7) and the respective pole shoe (6), - wherein at least one axially extending cooling channel (11, 12) for guiding a coolant is formed at the respective pole shoe (6) between the rotor winding (7) and the respective pole shoe (6), which has a channel wall (13) limiting the cooling channel (11, 12) transversely to the axial direction, characterized by - that the respective insulating layer (8) and the respective channel wall (13) consist of an electrically insulating material which is molded onto the respective pole shoe (6).

2. Machine (1) according to claim 1 , characterized by - that the respective channel wall (13) and the respective insulation layer (8) have a common insulation section (14) which on the one hand limits the respective cooling channel (11, 12) transversely to the axial direction and on the other hand abuts the respective pole shoe (6) transversely to the axial direction.

3. Machine (1) according to any one of the preceding claims, characterized by - that the respective pole shoe (6) has two pole shoe sides (15, 16) which are turned away from each other in the circumferential direction, - that at least one such cooling channel (11, 12) is formed on at least one pole shoe side (15, 16) of each pole shoe (6).

4. Machine (1) according to claim 3, characterized by - that such a cooling channel (11, 12) is formed on both pole shoe sides (15, 16) of the respective pole shoe (6), wherein the cooling channel (11) arranged on one pole shoe side (15) is arranged radially offset to the cooling channel (12) arranged on the other pole shoe side (16).

5. Machine (1) according to any one of the preceding claims, characterized by - that a winding carrier (17) is formed at an axial pole shoe end on the respective pole shoe (6), which carries a section of a winding head (18) of the rotor winding (7), - that the respective winding carrier (17) has at least one groove structure (19) on an outer surface axially away from the respective pole shoe (6), which fluidically connects at least one of the cooling channels (11, 12) to a coolant connection (20) for supplying or removing the coolant.

6. Machine (1) according to claims 3 and 5, characterized by - that the groove structure (19) on the outside of the respective winding carrier (17) fluidically connects both cooling channels (11, 12) to the one coolant connection (20) for supplying or removing the coolant.

7. Machine (1) according to claim 5 or 6, characterized by - that the respective winding carrier (17) consists of an electrically insulating material which is molded onto the respective pole shoe (6).

8. Machine (1) according to claim 7, characterized by - that the respective insulating layer (8), the respective channel wall (13) and the respective winding carrier (17) consist of the same electrically insulating material which is molded onto the respective pole shoe (6).

9. Machine (1) according to any one of the preceding claims, characterized by - that the respective insulating layer (8), the respective channel wall (13) and / or the respective winding carrier (17) contains an electrically insulating polymer, preferably a thermosetting plastic, in particular an epoxy molding compound, which is molded onto the respective pole shoe (6).

10. Machine (1) according to any one of claims 5 to 9, characterized by - that the slot structure (19) of the respective winding carrier (17) is axially covered and closed by the rotor winding (7).

11. Machine (1) according to claim 10, characterized by - that the rotor winding (7) is configured such that a cavity (22) is formed on the respective winding carrier (17) between the rotor winding (7), the respective cooling channel (11, 12) and the slot structure (19), which is fluidically connected to the slot structure (19).

12. Machine (1) according to claim 10 or 11 , characterized by - that the rotor winding (7) is configured in multiple layers and has at least three winding layers (23) that wrap around the respective pole shoe (6), - that a first winding layer (23.1 ) rests directly on the respective winding carrier (17), axially covers the slot structure (19) on the respective winding carrier (17) and runs outside the respective cooling channel (11,12), - that a second winding layer (23.2) lies directly on the first winding layer (23.1) and axially covers the slot structure (19) on the respective winding carrier (17) and runs outside the respective cooling channel (11, 12), - that a third winding layer (23.3) lies directly on the second winding layer (23.2) and axially covers the slot structure (19) and the respective cooling channel (11, 12) on the respective winding carrier (17).

13. Machine (1) according to claim 12, characterized by - that a fourth winding layer (23.4) rests directly on the third winding layer (23.3) and axially covers the slot structure (19) and the respective cooling channel (11, 12) on the respective winding carrier (17).

14. Machine (1) according to claim 13, characterized by - that a fifth winding layer (23.5) lies directly on the fourth winding layer (23.4) and axially covers the slot structure (19) and the respective cooling channel (11, 12) on the respective winding carrier (17).

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