Rotor arrangement, electric machine and method for producing rotor arrangement

Abstract

The invention relates to a rotor device (1) comprising: a rotor body (2) formed in an axial direction with a plurality of slots (3) for receiving windings (4); rotor poles (5) each formed in the radial direction between each pair of the slots (3); windings (4) which extend in the slots (3) and surround the rotor poles (5); groove closing elements (6) which close the grooves (3) in the radial direction; at least one separating body (7) which is arranged in one of the slots (3) in the circumferential direction between two of the windings (4), the separating body (7) comprising at least one continuous cooling channel (8) which extends in the axial direction and through which a cooling medium can flow; and a heat conducting element (21) resting at least partially against at least one of the groove walls (20) of the groove (3).

Description

Technical Field

[0001] The present invention relates to a rotor assembly comprising: a rotor body having a plurality of slots formed in an axial direction for receiving windings; rotor poles, each formed in a radial direction between each pair of slots; windings extending in the slots and surrounding the rotor poles; slot closing elements closing the slots in a radial direction; and at least one partition body circumferentially arranged in one of the slots between two windings, wherein the partition body includes at least one continuous cooling channel extending in an axial direction through which a cooling medium can flow. Background Technology

[0002] Electric motors are increasingly being used to power motor vehicles as an alternative to internal combustion engines that require fossil fuels. Significant efforts have been made to improve the suitability of electric drives for everyday use and to provide users with the driving comfort they are accustomed to.

[0003] In the development of electric motors, especially those intended for use in electric vehicle axles or hybrid powertrain modules, there is a continuous need to increase power density and efficiency while reducing manufacturing costs. In this context, designing motors as externally excited synchronous motors (EESMs) is known. An EESM is a special type of synchronous motor in which the magnetic field in the rotor is not generated by permanent magnets, but by energized coils. These coils are often referred to as field coils or excitation coils. To energize the coils in the rotating rotor, a suitable transformer system must be used to supply power.

[0004] Due to the manufacturing process, gaps may occur between any two excitation windings of the rotor. Specifically, a support body or separator body is inserted into these gaps, completely or substantially filling them. Particularly in high-speed applications, the separator body protects the windings of the excitation coils from unintentional movement in the centrifugal force field. EP1 494 335 B1 discloses a corresponding separator body between adjacent excitation coils.

[0005] Especially in terms of improving power density and efficiency, it is necessary to cool the rotor and dissipate heat energy during operation, particularly in the case of externally excited synchronous motors. For example, air-cooled rotors or fluid-cooled hollow shafts are known from the prior art. DE102018220810A1 discloses a fluid-cooled rotor for an electric motor and an externally excited synchronous motor with rotor windings that are directly cooled or near-heat-loss cooled. EP3618241A1 discloses a fluid-cooled hollow shaft with tapered walls. Summary of the Invention

[0006] The object of the present invention is to provide a suitable device for dissipating thermal energy from the rotor of an externally excited synchronous motor that provides a compact structure and high operational reliability.

[0007] This objective is achieved by a rotor assembly comprising: a rotor body having a plurality of slots formed in the axial direction for receiving windings; rotor poles, each formed in the radial direction between each pair of slots; windings extending in the slots and surrounding the rotor poles; slot closing elements closing the slots in the radial direction; and at least one partition body arranged circumferentially in one of the slots between two windings, wherein the partition body includes at least one continuous cooling channel extending in the axial direction through which a cooling medium can flow, wherein a heat-conducting element rests at least partially against at least one of the slot walls.

[0008] The advantage of this is that, due to the heat-conducting elements, power losses in the form of heat can be dissipated as close to their source as possible. Furthermore, compared to cooling between slots within the rotor body itself, the integration of the heat-conducting elements results in minimal intervention in the rotor's electromagnetic design.

[0009] Compared to existing technologies, this achieves improvements in high-speed stability, thermal behavior, efficiency, and available torque density.

[0010] Each winding is well thermally connected to the separator body at its outer winding layer. In contrast, the thermal connection of the inner winding layer is relatively poor due to the limited thermal conductivity of the insulation and filler materials. Now, thermally conductive elements can largely prevent or reduce the high temperatures that occur in these areas during motor operation. This helps maintain high rotor excitation power, which also has a positive impact on the motor's efficiency and power density.

[0011] The heat-conducting elements are preferably made of a material with good thermal conductivity, so that heat is dissipated to less critical areas, especially from the inner winding layers. This results in a uniform heat distribution in the rotor and can correspondingly reduce the maximum rotor temperature or increase the rotor excitation power, as mentioned above, which has a positive impact on the machine's efficiency and power density.

[0012] Preferably, each of the multiple slots has at least one heat-conducting element. Particularly preferred is that each of all slots has at least one heat-conducting element. In principle, it is possible to accommodate multiple heat-conducting elements in a single slot.

[0013] Thermal conductive elements can be designed as a single piece or multiple pieces.

[0014] It is also preferable to design multiple heat-conducting elements to be identical. Most preferably, all heat-conducting elements are designed to be identical.

[0015] According to a preferred embodiment, the heat-conducting element has a constant cross-section in the axial direction.

[0016] According to one embodiment, the rotor assembly includes a rotor shaft designed as a hollow shaft and having an opening in the radial direction for guiding a cooling medium. The opening connects to a cooling channel for guiding the cooling medium. Advantageously, the opening is connected to the cooling channel via another component, which, together with the opening and the cooling channel, forms a channel system. Thus, the cooling channel is connected to a cooling system via the channel system. Particularly advantageously, the cooling channel is connected to the cooling system on both sides via corresponding additional components, thereby forming a closed cooling loop.

[0017] According to one embodiment, a cavity is formed in the slot and the cavity is demarcated by one of the windings and the separator body, wherein the cavity includes a potting material. An advantage of this embodiment is that the potting material in the cavity improves the thermal connection between the windings and the separator body. The cavity is caused by manufacturing tolerances of the windings and the separator body.

[0018] According to one embodiment, the cooling medium is a cooling liquid. An advantage of this embodiment is that the cooling liquid has a higher heat capacity and higher thermal conductivity than a gas, and therefore enables better heat dissipation or power loss reduction. Specifically, the cooling liquid comprises oil and / or water.

[0019] According to one embodiment, the rotor body is designed as a laminated stack. An advantage of this embodiment is that it minimizes eddy current losses within the rotor body.

[0020] According to an advantageous embodiment of the invention, the thermally conductive element can be made of a non-ferromagnetic material, particularly a non-ferromagnetic metallic material, especially aluminum and / or copper. The thermally conductive element is preferably produced from copper or aluminum by extrusion. The material properties of copper or aluminum allow for good mechanical properties and good thermal conductivity within the thermally conductive element. Since aluminum and copper are not ferromagnetic, the electromagnetic function of the machine is unaffected. Alternatively, the thermally conductive element can be produced from plastic by extrusion, where, however, a lower thermal conductivity is generally required in this case.

[0021] According to other preferred further improvements of the invention, the thermally conductive element may comprise a deep-drawn or extruded profile. In particular, the profile may have a non-closed cross-sectional profile, such as a U-shaped or V-shaped profile.

[0022] Furthermore, according to an equally advantageous embodiment of the invention, the heat-conducting element may at least partially have a coating formed of an electrically insulating material. Therefore, the heat-conducting element can be electrically insulated from live parts to specifically avoid electrical contact between excitation coils or between the excitation coil and the vehicle, and thus meet the requirements regarding high-voltage safety. The coating can be achieved, for example, by painting, overmolding, or by an adhesive bonding layer. For example, for electrical insulation with limited requirements, the heat-conducting element supported by aluminum can also be anodized. In cases of high requirements, it can be covered with a film, overmolded with plastic, or coated with an alternative material on the contact surfaces of the rotor windings. This ensures that no electrical short circuits occur between excitation coils or between the excitation coil and the vehicle.

[0023] According to another particularly preferred embodiment of the invention, the axial extension of the heat-conducting element may correspond to at least 80%, preferably at least 90%, and particularly preferably at least 100% of the axial extension of the rotor body.

[0024] Its special effect lies in achieving thermal uniformity along the entire length of the rotor. In principle, the heat-conducting element can also protrude axially beyond the rotor body, which can further help improve the cooling effect of the heat-conducting element.

[0025] Furthermore, the present invention can be further developed such that the heat-conducting element covers at least 50%, preferably at least 65%, and particularly preferably at least 75% of the circumferential contour of the groove wall. The advantage of this embodiment is that it can achieve good and comprehensive heat dissipation and homogenization.

[0026] The invention can also be advantageously further developed by integrally, and particularly also integrally, connecting the cooling ribs to the heat-conducting element. In this respect, the cooling ribs can increase the surface area and thus optimize heat transfer from the winding to the heat-conducting element. For example, the cooling ribs can be incorporated into the heat-conducting element by means of an extrusion process.

[0027] Therefore, a heat-conducting element with one or more cooling ribs essentially achieves two functions. On the one hand, the heat-conducting element helps to hold the winding in the slot even under the influence of centrifugal force, and on the other hand, it provides optimized cooling for the inner winding layer within the slot. Thus, the rotor winding is supported in a high-speed, stable manner via the cooling ribs, and is simultaneously cooled.

[0028] According to an advantageous embodiment of the invention, the cooling ribs can be integrally formed with the heat-conducting element. This embodiment offers advantages in terms of manufacturing, providing particularly good heat transfer and a particularly advantageous cooling rib shape.

[0029] Preferably, the cooling ribs have a constant cross-section in the axial direction. Furthermore, this embodiment also particularly allows for the use of extrusion and / or injection molding methods to manufacture the separator body.

[0030] Preferably, the heat-conducting element has multiple cooling ribs. In this respect, it is particularly preferred that the cooling ribs are opposite to each other in the groove.

[0031] It is also preferred that the cooling ribs have substantially the same geometry, which is particularly advantageous in terms of manufacturing and simplifies the modeling of heat transfer.

[0032] The partition body is preferably connected to a slot closure element that radially closes the slot and supports the partition body in a high-speed, stable manner. The slot closure element is preferably made of a non-ferromagnetic and non-conductive material, such as plastic, so that the electromagnetic behavior of the machine is unaffected and no additional eddy current losses occur in this component. The slot closure element can be manufactured by plastic injection molding or extrusion and connected to the partition body by form fitting or adhesive bonding. Alternatively, the slot closure element can be directly injection molded onto the partition body. In this context, the slot closure element can be integrally connected by plastic overmolding of the partition body.

[0033] Finally, the invention can also advantageously be implemented such that the slot closure element and the partition body are integrally connected. The advantage of this design is that the integral connection allows the slot closure element and the partition body to be manufactured as a single component. This reduces the complexity of the rotor assembly. Another advantage is that the integral connection provides more stable components. Particularly preferably, the slot closure element and the partition body are integrally designed, for example, from aluminum or plastic.

[0034] The object of the present invention is also achieved by an electric motor comprising the rotor assembly described in any one of the preceding claims, wherein the motor is designed as an externally excited synchronous motor.

[0035] The object of the present invention is also achieved by a method for producing a rotor device, the method comprising the following steps:

[0036] - A rotor body is provided, which has multiple slots formed in the axial direction for receiving the windings.

[0037] - Provide at least one heat-conducting element.

[0038] - At least one partition body is provided, which can be arranged circumferentially between two windings in one of the slots. The partition body includes at least one continuous cooling channel extending axially through which a cooling medium can flow.

[0039] - Insert the heat-conducting element into one of the slots in the rotor body, such that the heat-conducting element rests at least partially against the slot wall.

[0040] - The rotor body is wound so that the windings extend in the slots.

[0041] - Insert the separator body into the slot so that the separator body is arranged circumferentially between the two windings in the slot. Attached Figure Description

[0042] The invention will now be explained in more detail with reference to the accompanying drawings without limiting the overall concept of the invention.

[0043] In the attached diagram:

[0044] Figure 1 A detailed representation of a first embodiment of a rotor having a first partition body is shown in cross-sectional view.

[0045] Figure 2 A schematic cross-sectional view of a first embodiment of the heat-conducting element is shown.

[0046] Figure 3 A detailed representation of a second embodiment of a rotor having a first partition body is shown in cross-sectional view.

[0047] Figure 4 A schematic cross-sectional view of a second embodiment of the heat-conducting element is shown. Detailed Implementation

[0048] Figure 1 A rotor assembly 1 for an externally excited synchronous motor is shown, the rotor assembly comprising: a rotor body 2 having a plurality of slots 3 formed in the axial direction for receiving windings 4; and rotor poles 5 each formed in the radial direction between each pair of slots in the slots 3. The rotor assembly 1 also has windings 4 extending in the slots 3 and surrounding the rotor poles 5.

[0049] The slot 3 is closed radially by the slot closing element 6. The separator body 7 is arranged circumferentially between the two windings in the winding 4 in each slot of the slot 3. The separator body 7 has two continuous cooling channels 8, each extending axially and parallel to the others, through which the cooling medium can flow.

[0050] Figure 1Slot 3 is shown particularly clearly, extending axially through rotor body 2. Electrifiable windings 4 are arranged in slot 3, each winding surrounding a rotor pole 5 formed between two slots 3. Slot 3 is radially closed by slot closing elements 6 arranged circumferentially between two adjacent rotor poles 5. Each rotor pole 5 forms a stop in the radial direction, facing one of the slots 3 circumferentially. Every two stops facing slot 3 thus form a form-fitting reception for slot closing element 6. This form-fitting reception secures slot closing element 6 against centrifugal force during operation. In the inward radial direction, a separator body 7 is arranged adjacent to slot closing element 6 in slot 3, such that the separator body is substantially radially oriented at the center between two adjacent windings 4.

[0051] In this respect, the separator body 7 has two side surfaces aligned with the winding 4 in the circumferential direction and extending parallel to each other and parallel to an imaginary plane oriented in the radial direction. The separator body 7 is connected here to the slot closure element 6. In the illustrated embodiment, the connection is a form-fit connection; however, alternatively, force-fit connections or material-bonded connections and combinations thereof are also possible. In the axial direction, cooling channels 8 are formed in the separator body 7, arranged equidistant from the side surfaces in the circumferential direction and equidistant from each other in the radial direction. This allows for uniform heat dissipation.

[0052] Cooling channels 8 extend along the entire axial length of the separator body 7, and coolant flows through these channels during operation. In this respect, the cooling channels are aligned parallel to the axis of rotation (not shown) of the rotor body 2. In the circumferential direction, cavities 9 are formed in slots 3 between one winding of the winding 4 and the separator body 7, and these cavities are filled with a potting compound 10. The potting compound 10 allows for better thermal connection between the winding 4 and the separator body 7.

[0053] In the exemplary embodiment shown, the partition body 7 is formed of aluminum and has an electrically insulating coating on at least a portion of its outer surface. The slot closure element 6 and the partition body 7 are integrally connected.

[0054] Figure 1 It is clearly shown that each of the windings 4 is well thermally connected to the separator body 7 through its outer winding layer. In contrast, the inner windings have relatively poor thermal connection due to the limited thermal conductivity of the potting compound 10. Therefore, during operation, the temperature in this area may be higher than that in the effective length region, and the rotor excitation power must be limited accordingly, which negatively impacts the motor's efficiency and power density.

[0055] Therefore, at least one heat-conducting element 21 is arranged on the wall 20 of the groove 3, and the heat-conducting element rests against the corresponding groove wall 20. The heat-conducting element 21 is made of non-ferromagnetic material, especially non-ferromagnetic metal material, especially aluminum and / or copper.

[0056] from Figure 2 As can be clearly seen, the heat-conducting element 21 is a deep-drawn or extruded profile 22 having a coating 27 formed of an electrically insulating material. Here, the profile 22 is not circumferentially closed but open, and in the broadest sense, it is reminiscent of a U-shape or V-shape. Thus, the heat-conducting element 21 covers at least 50%, preferably at least 65%, and particularly preferably at least 75% of the circumferential profile 25 of the groove wall 20, which has proven particularly advantageous in terms of effective heat dissipation.

[0057] exist Figures 3 to 4 In the illustrated embodiment, the heat-conducting element 21 has two cooling ribs 26 that extend circumferentially from the heat-conducting element 21 and engage with the winding 4. The two cooling ribs are mirror-symmetrically opposite each other in the slot. The cooling ribs 26 are integrally connected to the heat-conducting element 21, particularly integrally connected.

[0058] from Figures 1 to 4 It is understood that the rotor device 1 can be manufactured as follows. First, a rotor body 2 is provided, which has a plurality of slots 3 formed in the axial direction for receiving the windings 4. In addition, at least one heat-conducting element 21 and at least one partition body 7 are provided. The partition body can be positioned in one of the slots 3 in the circumferential direction between two windings in the windings 4. The partition body 7 includes at least one continuous cooling channel 8, which extends in the axial direction and through which the cooling medium can flow.

[0059] Then, the heat-conducting element 21 is inserted into one of the slots 3 of the rotor body 2, such that the heat-conducting element 21 rests at least partially against the slot wall 20 of the slot 3. Subsequently, the rotor body 2 is wound so that the winding 4 extends in the slot 3. Finally, the separator 7 is inserted into the slot 3, so that it is arranged circumferentially between the two windings of the winding 4 in the slot 3.

[0060] This invention is not limited to the embodiments shown in the accompanying drawings. Therefore, the above description should not be considered limiting but rather illustrative. The appended claims should be understood to indicate the presence of the stated features in at least one embodiment of the invention. This does not exclude the presence of other features. Where the claims and the above description define "first" and "second" features, this designation is used to distinguish between two features of the same type, without specifying any order of priority.

[0061] List of reference numerals in the attached figures

[0062] 1. Rotor assembly

[0063] 2 Rotor body

[0064] 3 slots

[0065] 4 windings

[0066] 5 rotor poles

[0067] 6-slot enclosed element

[0068] 7. Separate body

[0069] 8 cooling channels

[0070] 9 chambers

[0071] 10. Encapsulating Compounds

[0072] 20 Tank Wall

[0073] 21 Thermal conductive elements

[0074] 22 profile

[0075] 25 Outline

[0076] 26 Cooling ribs

[0077] 27 Coating

Claims

1. A rotor device (1), comprising: - Rotor body (2), wherein the rotor body has a plurality of slots (3) formed in the axial direction for receiving the windings (4), - Rotor magnetic poles (5), each of which is formed radially between each pair of slots in the slots (3). - Winding (4), the winding extending in the slot (3) and surrounding the rotor pole (5), - A groove closing element (6), which closes the groove (3) along the radial direction. - At least one separator body (7) is arranged circumferentially in one of the slots (3) between two windings in the winding (4). -The partition body (7) includes at least one continuous cooling channel (8) extending along the axial direction and through which a cooling medium can flow. Its features are, A heat-conducting element (21) rests against at least one of the groove walls (20) of the groove (3) at least partially.

2. The rotor device (1) according to claim 1, Its features are, The heat-conducting element (21) is made of non-ferromagnetic material, particularly non-ferromagnetic metal material, particularly aluminum and / or copper.

3. The rotor device (1) according to claim 1 or 2, Its features are, The thermally conductive element (21) includes a deep-drawn or extruded profile (22).

4. The rotor device (1) according to any one of the preceding claims, Its features are, The thermally conductive element (21) has at least a partial coating (27) formed of an electrically insulating material.

5. The rotor device (1) according to any one of the preceding claims, Its features are, The axial extension of the heat-conducting element (21) corresponds to at least 80%, preferably at least 90%, and particularly preferably at least 100% of the axial extension of the rotor body (2).

6. The rotor device (1) according to any one of the preceding claims, Its features are, The heat-conducting element (21) covers at least 50%, preferably at least 65%, and particularly preferably at least 75% of the circumferential profile (25) of the groove wall (20).

7. The rotor device (1) according to any one of the preceding claims, Its features are, The heat-conducting element (21) has at least one cooling rib (26) that extends from the heat-conducting element (21) along the circumferential direction and engages with the winding (4).

8. The rotor device (1) according to any one of the preceding claims, Its features are, The cooling rib (26) is integrally, and particularly integrally, connected to the heat-conducting element (21).

9. An electric motor comprising a rotor assembly (1) according to any one of the preceding claims, wherein, The motor is designed as an externally excited synchronous motor.

10. A method for producing a rotor assembly (1), the method comprising the following steps: - A rotor body (2) is provided, wherein a plurality of slots (3) are formed in the axial direction for receiving the windings (4). - Provide at least one heat-conducting element (21), - At least one partition body (7) is provided, which is circumferentially positioned in one of the slots (3) between two windings in the winding (4), wherein the partition body (7) includes at least one continuous cooling channel (8) extending in the axial direction, and through which a cooling medium can flow. - The heat-conducting element (21) is inserted into one of the slots (3) of the rotor body (2) such that the heat-conducting element (21) rests at least partially against the slot wall (20) of the slot (3). - The rotor body (2) is wound so that the winding (4) extends in the slot (3), - Insert the separator body (7) into the slot (3) such that the separator body is arranged in the slot (3) in the circumferential direction between the two windings in the winding (4).

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