Electric machine

Abstract

The invention relates to an electric machine (1) with a stator (2) and with a rotor (3) which is rotatable about an axis of rotation (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 on the respective pole shoe (6) between the rotor winding (7) and the respective pole shoe (6), which has a channel wall (13) that limits the cooling channel (11, 12) transversely to the axial direction. A simplified structure results when the respective insulating layer (8) and the respective channel wall (13) consist of an electrically insulating plastic which is molded onto the respective pole shoe (6) by overmolding or potting.

Description

[0001] The present invention relates to an electrical machine according to the preamble of claim 1.

[0002] An electrical machine of this type is known, for example, from DE 10 2021 103 441 A1 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.

[0003] From DE 10 2017 213 960 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.

[0004] From DE 199 64 061 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.

[0005] From DE 20 2017 006 523 U1 and from EP 3 871 323 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] The electrical machine is appropriately an electrically excited synchronous machine.

[0011] 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.

[0012] 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”.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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 inside 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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, again 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 appropriately dimensioned in the circumferential direction as two winding layers, such that the first winding layer and the second winding layer run radially next to the respective cooling channel, while the third winding layer and any further winding layer can radially overlap the respective cooling channel and thus cover it in the circumferential direction.

[0023] 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.

[0024] 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.

[0025] 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 be integral areas or sections of this unit, even if this is depicted differently in the drawings.

[0026] 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.

[0027] They show, schematically, Fig. 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. Fig. 6 a simplified longitudinal section of the electric machine according to a section line VI in Fig. 5.

[0028] According to the Fig. 1 to 6 comprises an electric machine 1 only in Fig. The figure includes a stator 2 (indicated in 6) and a rotor 3, which is rotatable about a rotational axis 4 relative to the stator 2. The figures shown in the Fig. 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 section plane of the Fig. 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 perpendicular 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.

[0029] The rotor 3 has a laminated core 5 on which several pole shoes 6 are formed, which are arranged distributed in the circumferential direction and which carry a rotor winding 7. In the Fig. In each of the numbers 1 to 5, only one of these pole shoes 6 is shown, representing all pole shoes 6. The other pole shoes 6, not shown, are functionally identical in design to the one in the Fig. Pole shoe 6 shown in 1 to 5.

[0030] 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.

[0031] 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.

[0032] According to Fig. 1. The respective channel wall 13 and the respective insulation layer 8 have a common insulation section 14, which on one side borders 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.

[0033] 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 the Fig. In the first example, the first cooling channel 11 shown on the right is located 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, located 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 the Fig. 1 the radial offset is exactly as large as the radial width of the respective cooling channel 11, 12.

[0034] According to the Fig. 2 to 6, a winding carrier 17 is arranged or formed at one axial pole shoe end of each pole shoe 6. The winding carrier 17 covers in the Fig. 2 to 5 remove the associated pole shoe 6, so that the pole shoe 6 and the lamination stack are in the Fig. 2 to 5 are designated only with a broken reference line. The respective winding carrier 17 carries a section of a winding head 18 of the rotor winding 7 assigned to the respective pole shoe 6, which is located in the Fig. 3 to 5 is only partially recognizable or only partially manufactured. According to the Fig. The respective winding carrier 17 has 2 to 6 on an outer side facing axially away from the respective pole shoe 6, which is located in the Fig. On the outer surface of the respective winding carrier 17, at least one groove structure 19 is provided, 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 discharge the coolant. Advantageously, the groove structure 19 connects both cooling channels 11, 12 to the coolant connection 20 on the outer surface of the respective winding carrier 17, which thereby serves as a common coolant connection 20. In the example shown, the coolant connection 20 is formed centrally on the respective winding carrier 17 with respect to the circumferential direction. 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 discharging the coolant and which is fluidically connected to the respective coolant connection 20 in a suitable manner.

[0035] 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.

[0036] As can be seen in particular from the Fig. If the result is 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 arranged according to... Fig. 6 shall be configured 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, which 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.

[0037] A first winding layer 23.1 is located according to Fig. 3 directly on the respective winding carrier 17 axially and covers the slot structure 19 on the winding carrier 17 and runs in an axial projection of the respective cooling channel 11, 12 outside the respective cooling channel 11, 12. In Fig. Figure 3 shows the first winding layer 23.1 on the winding carrier 17.

[0038] A second winding layer 23.2 is located according to Fig. 4 directly on the first winding layer 23.1 axially and covers the slot structure 19 axially on the respective winding carrier 17 and also runs outside the cooling channels 11, 12 in an axial projection of the respective cooling channel 11, 12. Fig. Figure 4 shows the second winding layer 23.2, which is wound congruently onto the first winding layer 23.1.

[0039] According to Fig. 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 now also the cooling channels 11, 12 on the respective winding carrier 17. This forms the cavities 22 between the rotor winding 7 and the respective winding carrier 17, which are fluidically connected to the slot structure 19.

[0040] One in Fig. The fourth winding layer 23.4, indicated in the diagram, now lies directly on top of the third winding layer 23.3 axially and covers the slot structure 19 and the cooling channels 11, 12 on the respective winding carrier 17. The same applies to a layer in Fig. 1. Indicated fifth winding layer 23.5, 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 in the Fig. 1 to 5 are indicated only outside the winding carrier 17. Reference symbol list 1 machine 2 Stator 3 Rotor 4 Rotation axis 5 sheet metal package 6 pole shoe 7 Rotor winding 8 Insulation layer 9 shaft 10 caps 11 Cooling channel 12 Cooling channel 13 Canal wall 14 Insulation section 15 Pole shoe side 16 Pole shoe side 17 winding carriers 18 winding head 19 groove structure 20 Coolant connection 21 Coolant channel 22 Cavity 23 winding position QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 103 441 A1

[0002] DE 10 2017 213 960 A1

[0003] DE 199 64 061 A1

[0004] DE 20 2017 006 523 U1

[0005] EP 3 871 323 B1

[0005]

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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