Dynamoelectric machine having a thermosiphon with a highly efficient condenser unit

Abstract

The invention relates to a rotary dynamoelectric machine (1) having a stator (2) and a rotor (5) supported rotatably about an axis (21), the rotor (5) being connected to a hollow shaft (6) thermally conductively and fixedly for conjoint rotation, the hollow shaft (6) forming a closed cavity and being designed as a thermosiphon which axially has at least one evaporator zone (8) and a condenser zone (9), the condenser zone (9) having at least one fan (12) and at least one cooling disc (17) thermally coupled to the hollow shaft (6), the fan (12) and the cooling disc (17) being arranged coaxially with respect to the hollow shaft (6) and being connected to the condenser portion (9) thermally conductively via the wall of the hollow shaft (6).

Description

[0001] 202413337

[0002] 1

[0003] Description

[0004] Dynamoelectric machine with a thermosiphon and a high-efficiency capacitor unit

[0005] The invention relates to a dynamo-electric machine with a thermosiphon formed in a shaft and a highly efficient capacitor unit.

[0006] Rotary dynamoelectric machines typically cool their rotors with a cooling airflow generated by an axial fan. However, if the heat load of the rotor is greater, such a cooling airflow is no longer sufficient. In such cases, hollow shafts are used, containing a cooling medium that conducts the heat from the rotor outwards and axially through this shaft.

[0007] Such a thermosiphon has an evaporator and a condenser, with the condenser generally being considered the limiting factor in this type of cooling system. Therefore, it is necessary to increase heat dissipation on the fan side. However, existing fans, which also generate an airflow to cool the motor via the housing, exhibit relatively low thermal coupling to the shaft because the fan hub is comparatively short and the connection between the fan hub and the fan plate has a small cross-section.

[0008] Enlarging the fan and thus increasing the airflow would indeed draw more heat energy from the shaft and increase the capacitor's performance, but would also increase the fan's friction coefficient.

[0009] However, in highly efficient motors larger than IE3, this friction factor of the fan significantly impacts the motor's efficiency. Oversizing the fan solely to improve the capacitor's function would therefore diminish the positive effect of the thermosiphon in the shaft.

[0010] Thus far, the condenser side has been operated with an airflow rate solely tailored to the required motor cooling. The resulting limited effectiveness of the condenser in the thermosiphon has been accepted accordingly. 202413337

[0011] 2

[0012] Another possibility is shown, for example, in DE 10 2009 051 114 A1, where an electric machine has a rotor with a hollow shaft that forms a closed cavity. This closed cavity, which holds a refrigerant, has a three-dimensional transport structure for transporting the refrigerant. The heat generated is thus transferred axially to the outside via this transport structure and cooled there by a cooling airflow.

[0013] The disadvantage is that, in order to adequately cool the refrigerant, a correspondingly long axial cooling surface must be provided to ensure sufficient cooling of the rotor.

[0014] Based on this, the invention aims to create a compact dynamoelectric machine with a thermosiphon arranged in the shaft, particularly for energy efficiency class IE3 and higher. The noise level of a fan should also be kept as low as possible.

[0015] The problem can be solved by the characteristics of an independent claim.

[0016] Advantageous configurations can be found in the dependent claims.

[0017] According to the invention, a combination of a fan and cooling discs is used to improve heat dissipation at the condenser of a hollow shaft in a rotary dynamo-electric machine. This enables sufficient cooling of a compact dynamo-electric machine with comparatively low fan noise. The hollow shaft is thus designed as a thermosiphon with at least one evaporator section and one condenser section.

[0018] The fan of the rotary dynamo-electric machine, in particular of a motor, is designed solely according to the cooling capacity required by that motor. To further increase heat dissipation, especially via the hollow shaft, cooling discs are additionally provided on the hollow shaft in the area of ​​the capacitor section according to the invention. These discs, however, cause virtually no friction during operation of the dynamo-electric machine—i.e., during rotation of the hollow shaft—that would reduce the efficiency of the dynamo-electric machine. 202413337

[0019] 3

[0020] Since the cooling discs rotate with the hollow shaft and their outer contour is ideally uninterrupted, a scooping effect – and thus friction – is avoided. The cooling discs simply increase the cooling surface area of ​​the condenser section in a compact form.

[0021] The advantages of a motor fan lie in the creation of an airflow (by fan blades) that is guided over the motor housing, possibly by means of a fan shroud. However, excessive fan friction negatively impacts motor efficiency. Furthermore, the fan hub has a comparatively low thermal contact with the (hollow) shaft.

[0022] The cooling discs provide a comparatively good thermal connection to the (hollow) shaft without requiring the expenditure of efficiency-reducing frictional energy. Due to the large heat dissipation surfaces of the cooling discs, good heat radiation is achieved in the area of ​​the condenser unit. However, these cooling discs contribute almost nothing to significant air cooling.

[0023] The inventive design of the axial part of the hollow shaft, which is designed as a capacitor section, combines the advantages of a motor fan with the advantages of cooling discs to a required extent.

[0024] Advantageously, the cooling discs are positioned axially on the hollow shaft as individual modules. This allows – provided there is still space on the hollow shaft – the modular addition of further modules to increase the cooling capacity of the condenser unit. A module can contain one or more cooling discs.

[0025] The modules with their cooling discs can also be arranged axially behind the fan, i.e., between the motor and the fan. Advantageously, in this case, the fan has openings as close as possible to the shaft to supply the cooling discs with air. The openings are positioned radially close to the shaft and create a negligible airflow between the cooling discs, without any significant friction.

[0026] In another design, the cooling discs are positioned in front of the fan and their diameter increases towards the fan. This results in additional cooling, as the heated air radiated by the cooling discs is more effectively dissipated by the fan. 202413337

[0027] 4

[0028] The thermosiphon can be used both for cooling the rotor assembly and thus the short-circuit cage on the asynchronous motor, as well as for cooling permanent magnets in the rotor of a permanent magnet synchronous motor.

[0029] This increases the efficiency of the motor and / or the lifespan of the permanent magnets. The motor can therefore be operated at a higher utilization rate.

[0030] In the section of the hollow shaft designated as the evaporator, heat sources such as the rotor's laminated core and possibly the inner bearing race are thermally connected to the outer wall of the hollow shaft. In the section of the hollow shaft designated as the condenser, heat sinks such as fans, cooling discs, or cooling disc modules are also thermally connected to the outer wall of the hollow shaft. A thermosiphon transport zone may be located between the evaporator and condenser sections.

[0031] To increase the efficiency of the capacitor zone or capacitor section, it is designed to have a conical shape, at least in some sections.

[0032] To increase the efficiency of the capacitor zone, a microscale structure can be provided on the inner wall of the hollow shaft in addition to, or instead of, the conical profile.

[0033] Advantageously, this microscale structure is provided by an additive manufacturing process.

[0034] In another version, the modules and / or the fan can be directly "pressed" axially onto a hollow shaft segment. In other words, the capacitor section is directly "pressed" onto a hollow shaft segment.

[0035] The hollow shaft segment is now produced using conventional manufacturing methods, such as casting, turning, or drilling. The axial area, particularly the capacitor zone, is then augmented with additively manufactured structural elements, forming a microscale structure such as ribs, webs, pins, knobs, pores, or hollow bodies. This creates a mechanical connection between the hollow shaft segment and the capacitor zone wall. The printed capacitor section is therefore sealed. 202413337

[0036] 5

[0037] According to the invention, the efficiency of the dynamoelectric machine is increased by means of special structures, such as fine rod-shaped elements, porous networks, etc., on the inner contour of the capacitor zone, i.e., the inner wall of the hollow shaft. This is achieved according to the invention by an additive manufacturing process in which narrow material webs from 0.1 mm to several millimeters, as well as gaps from 0.01 mm to approximately...

[0038] Thicknesses of 2 mm or more are achievable. A preferred thickness of the material webs is approximately 1 mm, and a preferred gap width is approximately 0.5 mm. The resulting significant increase in surface area, especially inside the capacitor section, i.e., on the inner wall of the hollow shaft, increases the efficiency of the recooling of this capacitor.

[0039] The additive manufacturing process also creates a permanent gas tightness and lasting strength between the hollow shaft segment and the condenser zone, especially the wall of the condenser zone. The condensation of an evaporating liquid in this microscale structure now forms a film on the inside of the condenser zone. However, this film has previously hindered contact between the vapor and the, in particular, cooler surface, thus blocking or at least preventing the condensation process. By forming the fine ridges, ribs, gaps, or pores according to the invention using an additive manufacturing process, it is now ensured in every case that vapor comes into contact with the comparatively cool inner contour, thus enabling condensation of the cooling medium, i.e., the evaporating liquid.

[0040] Additionally, the interior of this condenser is conically shaped towards the evaporation zone to convey the condensate away from the condensation surface and towards the evaporation zone via the axial component of centrifugal force during operation of the dynamo-electric machine. This ensures more than sufficient conveying action of the cooling medium within the hollow shaft.

[0041] The fan and cooling fins are preferably made of a material with good thermal conductivity, such as aluminum, copper, or aluminum alloys or copper alloys.

[0042] Thus, according to the invention, a rotor with a thermosiphon is now provided which exhibits increased efficiency in the condenser area or condenser zone, since the cooler surrounding the condenser section is designed as a fan with cooling discs. This, together with an airflow generated by the fan during operation of the dynamo-electric machine, results in efficient cooling with a compact machine design. 202413337

[0043] 6

[0044] The invention and further advantageous embodiments are described in more detail with reference to the exemplary embodiments shown. These show:

[0045] FIG 1 shows a principal longitudinal section of a dynamoelectric rotary machine, FIG 2 shows a capacitor section,

[0046] FIGS. 3-5 show further embodiments of capacitor sections.

[0047] FIG 6-8 shows an embodiment of cooling disks of the condenser section.

[0048] It should be noted that terms such as "axial," "radial," "tangential," etc., refer to the axis 21 used in the respective figure or in the described example. In other words, the directions axial, radial, and tangential always refer to an axis 21 of the rotor 5 and thus to the corresponding axis of symmetry of the stator 2. "Axial" describes a direction parallel to the axis 21, "radial" describes a direction orthogonal to the axis 21, either towards or away from it, and "tangential" is a direction that is circular around the axis 21 at a constant radial distance and with a constant axial position. The expression "circumferential" is synonymous with "tangential."

[0049] With regard to a surface, e.g. a cross-sectional area, the terms "axial", "radial", "tangential", etc. describe the orientation of the normal vector of the surface, i.e. the vector that is perpendicular to the surface in question.

[0050] The term "coaxial components," e.g., coaxial components such as rotor 5 and stator 2, refers here to components that have the same normal vectors, meaning that the planes defined by the coaxial components are parallel to each other. Furthermore, the term implies that the centers of coaxial components lie on the same axis of rotation or symmetry. However, these centers may be located at different axial positions on this axis, and the planes in question may therefore have a distance greater than zero from each other. The term does not necessarily require that coaxial components have the same radius.

[0051] The term "complementary" in the context of two components that are "complementary" to each other means that their external forms are designed in such a way that one component can preferably be arranged completely within its complementary component, so that the inner surface of one component and the outer surface of the other are aligned.

[0052] 7. The surface of the other component should ideally touch completely or without gaps. Consequently, in the case of two complementary objects, the outer shape of one object is determined by the outer shape of the other. The term "complementary" could be replaced by the term "inverse".

[0053] For the sake of clarity, in some cases where components are present multiple times, not all components shown in the figures are provided with reference symbols.

[0054] The described embodiments can be combined in any way desired. Likewise, individual features of the respective embodiments can also be combined without departing from the essence of the invention.

[0055] FIG 1 shows a rotary dynamoelectric machine 1 comprising a stator 2 and a rotor 5. In this embodiment, the rotor 5 is designed as a squirrel-cage rotor, but it can also be a permanent magnet rotor, a rotor of a reluctance machine, or a rotor with a winding system.

[0056] The rotor 5 is non-rotatably connected to a hollow shaft 6, the hollow shaft 8 being supported in bearings 11. A non-rotatable connection is understood to be a torque-transmitting connection, such as a shrink-fit connection or another shaft-hub connection, between the lamination stack of the rotor 5 and the hollow shaft 8, which ensures good thermal coupling between the lamination stack of the rotor 5 and the outer wall of the hollow shaft 6 in this section (evaporator section 8). The housing of the electric machine 1 supports the bearing shields 15. Radially outside the stator 2, the housing features axially extending cooling fins 14, which guide a cooling airflow generated by a fan 12 along the housing. The fan 12 is housed in a fan shroud 13, which has air inlet openings 23 and air outlet openings 22.

[0057] In this embodiment, the hollow shaft 6 is hollow by means of a central axial recess 7, e.g., a bore, and has an evaporator section 8 in the area of ​​the rotor 5, optionally a transport section 10, and a condenser section 9. The axial extent of the evaporator zone 8 of the hollow shaft 6 corresponds at least to the axial extent of the laminated core of the rotor 5. Advantageously, in such an embodiment, the axial length ratio of evaporator section 8 to condenser section 4 is 1. 202413337

[0058] 8

[0059] In this version, the hollow shaft 6 has a central bore, but it is also conceivable that there are several axially parallel bores that lead into the correspondingly designed capacitor zone 9.

[0060] The capacitor section 9 has a fan 12 and cooling discs 17 or cooling disc modules 18, each of which is thermally well connected to the outer wall of the section of the hollow shaft 6 there.

[0061] The hollow shaft 6 forms a thermosiphon, whose condenser section 9 is particularly efficient due to the cooling discs 17 or cooling disc modules 18.

[0062] FIG 2 shows how cooling discs 17 are positioned axially on the fan 12 in the airflow 20 of the fan 12 on the hollow shaft 6. The cooling discs 17 of the fan 12 are arranged coaxially to the hollow shaft 6.

[0063] FIG 3 shows how cooling disc modules 18 are positioned axially on the fan 12 in the airflow 20 of the fan 12 on the hollow shaft 6. Each module 18 has a cooling disc 17. A module 18 can also be equipped with several cooling discs 17. These modules 18 can be modularly mounted onto the existing hollow shaft 6 as required. The fan 12 and the modules 18 are arranged coaxially with the hollow shaft 6.

[0064] FIG. 4 shows how cooling disc modules 18 are positioned axially behind the fan 12 on the hollow shaft 6. Advantageously, the fan 12 has openings 19 in the area of ​​its hub, i.e., near the hollow shaft 6, to supply the cooling discs 17 with air. Each module 18 has one cooling disc 17. A module 18 can also be provided with several cooling discs 17. The fan 12 and the modules 18 are arranged coaxially with the hollow shaft 6.

[0065] FIG 5 shows cooling discs 17, which are positioned in front of the fan 12 in the airflow 20 on the hollow shaft 6 and are arranged with an increasing diameter towards the fan 12. This provides an additional cooling effect, as the heated air radiated from the condenser section 9 is carried away by the fan 12.

[0066] FIGS. 6 to 8 show the arrangement, design, and position of openings 19 in the cooling discs 17. The outer contour of the cooling discs 17 remains closed, so that air friction during rotation is only minimally increased. 202413337

[0067] 9

[0068] According to the invention, the thermosiphon serves to cool the rotor lamination stack and thus, for example, a squirrel-cage rotor in an asynchronous motor. In a permanent magnet synchronous motor, the thermosiphon also serves to cool permanent magnets in the lamination stack of the rotor 5.

[0069] In the condenser zone 9, the cooling medium of the hollow shaft 6, e.g., an evaporator fluid, is cooled by the fan and the cooling discs 17. Crucially, efficient cooling of the evaporator fluid now occurs in the comparatively short axial section—that is, in the condenser zone 9—to ensure sufficient cooling efficiency for the entire dynamo-electric machine 1. The relatively short axial section of the condenser zone 9 also ensures a compact design for the dynamo-electric machine 1.

[0070] Advantageously, at least in the condenser section 9, microscale structures are present which are designed inside the hollow shaft 6 with an essentially conical shape towards the evaporator zone 8 in order to support a corresponding return transport of the cooling medium into the evaporator zone 8 of the hollow shaft 6.

[0071] This microscale structure generally features ribs and / or prisms and / or hollow bodies and / or surface-enlarging structures.

[0072] In the evaporator zone 8, a cooling medium is evaporated, absorbing heat, and then cooled back down in the condenser zone 9. Particularly in the transport zone 10, suitable packing materials in the hollow shaft 6 can improve the transport of the evaporated and / or cooled cooling medium. This is especially advantageous when the hollow shaft 6 is used in a wide variety of spatial configurations, for example, in hollow shafts in vehicles traveling on rough terrain.

[0073] The condenser zone 9 has an axially extending nozzle through which, for example, the coolant can be supplied and / or the operating pressure of the thermosiphon can be adjusted. The nozzle 21 is closed during operation of the dynamo-electric machine 1 in order to maintain the cooling circuit.

[0074] Such dynamoelectric machines 1 are used, among other things, as drives, particularly in vehicle technology, for e-cars, rail vehicles, mining trucks, etc., since sufficient cooling of the rotor 5 is now achieved even without forced ventilation. A 202413337

[0075] 10

[0076] Forced ventilation leads to insufficient cooling, especially of the rotor 5, in the case of highly dusty air and / or alternating operation of the motor with downtime.

[0077] In vehicle engineering, due to the limited space available, compact, high-performance drives are required, which are now fulfilled by a compact dynamoelectric machine 1.

[0078] 202413337

[0079] 11

[0080] Reference symbol list

[0081] 1 Dynamo-electric machine

[0082] 2 Stator

[0083] 3 winding system

[0084] 4 winding head

[0085] 5 Rotor

[0086] 6 Hollow shaft

[0087] 7 Cavity

[0088] 8 evaporator zones

[0089] 9 Capacitor zone

[0090] 10 Transport section

[0091] 11 warehouses

[0092] 12 fans

[0093] 13 fan hoods

[0094] 14 cooling fins

[0095] 15 Storage sign

[0096] 16 axial shaft extension

[0097] 17 discs

[0098] 18 disc segments

[0099] 19 Breakthrough

[0100] 20 airflow

[0101] 21 axle

[0102] 22 Air outlet

[0103] 23 Air intake

Claims

202413337 12 Patent claims 1. Rotary dynamoelectric machine (1) with a stator (2) and a rotor (5) rotatably mounted about an axis (21), wherein the rotor (5) rotates with a hollow shaft (6) and is thermally connected, wherein the hollow shaft (6) forms a closed cavity and is designed as a thermosiphon, which axially has at least one evaporator zone (8) and one condenser zone (9), wherein the condenser zone (9) has at least one fan (12) and at least one cooling disk (17) thermally coupled to the hollow shaft (6), wherein the fan (12) and cooling disk (17) are arranged coaxially to the hollow shaft (6) and are thermally connected to the condenser section (9) via the wall of the hollow shaft (6).

2. Rotary dynamoelectric machine (1) according to claim 1, characterized in that the cooling disks (17) are modularly constructed, in that one or more cooling disks (17) are provided per module (18) which can be thermally conductively mounted coaxially on the hollow shaft (6).

3. Rotary dynamoelectric machine (1) according to claim 1 or 2, characterized in that the cooling disks (17) or cooling disk modules (18) are arranged axially in front of and / or after the fan (12).

4. Rotary dynamoelectric machine (1) according to one of the preceding claims, characterized in that the fan (12) and / or the cooling discs (17) have openings (19).

5. Rotary dynamoelectric machine (1) according to one of the preceding claims, characterized in that at least the capacitor zone (9) has a micro-scale structure, wherein the micro-scale structure is designed as a rib-like structure and / or cone-shaped structure and / or pore-like network and wherein this structure is thermally conductively connected to an inner wall of the hollow shaft (6) of the capacitor zone (9).

6. Rotary dynamoelectric machine (1) according to one of the preceding claims, characterized in that at least the capacitor zone (9) is designed to be conical at least in sections. 202413337 13 7. Vehicle, such as an e-car, a rail vehicle or a mining truck, comprising at least one rotary dynamo-electric machine (1) according to any of the preceding claims.

8. Use of a rotary dynamoelectric machine (1) according to one of the claims 1 to 6 in the food industry or in an industrial environment, as a drive for pumps, compressors, fans.

Images