WO2021099190A1

WO2021099190A1 - Cooling system and component for an electric machine with hollow-conductor cooling

Info

Publication number: WO2021099190A1
Application number: PCT/EP2020/081720
Authority: WO
Inventors: Markus KLÖPZIG; Klaus Schleicher
Original assignee: Siemens Aktiengesellschaft
Priority date: 2019-11-21
Filing date: 2020-11-11
Publication date: 2021-05-27
Also published as: DE102019217964A1

Abstract

The invention specifies a cooling system (1) for a component of an electric machine having a central machine axis A. The cooling system (1) comprises - at least one hollow conductor (3), which is part of a winding of the electric machine and is designed to have a liquid coolant flowing through it, wherein, in at least one axial end region (3a), the hollow conductor (3) has an opening (4) for the introduction and/or discharge of coolant, - and at least one connection element (5), which has an inner coolant chamber (6), which is defined by a boundary wall (7) of the connection element (5), - wherein the connection element (5) has a first opening (5a), which encloses the axial end region (3a) of the at least one hollow conductor (3), - wherein the boundary wall (7) is sealed in relation to the at least one hollow conductor (3) via an encircling inner seal (8), - wherein the connection element (5) has a second opening (5b), which is designed for the introduction and/or discharge of coolant into the inner coolant chamber (6), - and wherein the connection element (5) has a casting compound (9) cast around it such that the casting compound (9) completely covers the transition region of the hollow conductor (3), via the inner seal (8), to the boundary wall (7) in the direction of the exterior surroundings (10). The invention also specifies a component (42) for an electric machine (41), the component comprising an electrical winding (44) and such a cooling system (1).

Description

description

Cooling system and component for an electrical machine with waveguide cooling

The present invention relates to a cooling system for a component of an electrical machine with a waveguide which is part of a winding of the electrical machine and which is designed to allow a liquid coolant to flow through it. The invention also relates to a construction part for an electrical machine with such a cooling system.

In known components for electrical machines, especially those with high power densities, measures must be taken to effectively dissipate the heat loss released in the windings of the mechanical engineering parts and thus avoid overheating of the winding. Such a component can be, for example, a stator or a rotor of the electrical machine. A large part of the heat loss in such components is generated as Joule heat by the current flow in the conductor segments of the respective winding. In order to dissipate these current heat losses from the Ro torwicklungen or stator windings, the windings according to the prior art are mostly indirectly coupled to a cooling system. In other words, the winding is cooled in that the winding is indirectly coupled to a coolant by other elements of the component, in particular a yoke and / or conductor insulation and / or a housing wall of the machine. The coolant can be, for example, cooling water or a cooling oil.

In contrast to the described machines with indirect winding cooling, it is also known from the prior art to arrange conductor segments of the winding in direct contact with a coolant so that they can be cooled directly. For this purpose, for example, the turned conductor be at least partially designed as a waveguide in order to be able to lead coolant in its interior, whereby the conductor can come into direct contact with the coolant without additional thermal coupling elements. With such a solution, the heat loss from the winding is dissipated directly where it arises. However, the electrical and fluid coupling of these waveguide coils is technically complex, since the individual winding segments have to be connected to an external circuit through electrical contacts and the individual windings are usually separated from one another to the inflows and outflows of an external coolant circuit must be connected during the run. In particular, this must be done in such a way that electrical short circuits caused by the coolant between the windings which are at different electrical potentials are avoided. For this it is usually necessary to connect the individual turns separately with separate supply lines and discharge lines for the coolant. This creates a high outlay in terms of equipment for connecting the individual lines. For example, each individual waveguide can be connected to a coolant inflow line and a coolant outflow line via two separate electrically insulating hose connectors. This large number of hose connectors takes up a lot of space and causes high manufacturing costs. In addition, such hose connectors are relatively maintenance-intensive.

In DE 102017204472 A1 the alternative concept of a fluidically encapsulated coolant chamber arranged in an axial end region is described, into which the open ends of the waveguide rods protrude. This ensures that the coolant can be fed from the coolant chamber into a plurality of such waveguide rods at the same time.

The fluid-tight encapsulation of such a common Kühlmit telkammer, however, has proven to be relatively expensive in terms of apparatus. In addition, the reliable electrical insulation of the individual waveguides fed from the common coolant chamber can be problematic. The object of the present invention is therefore to specify a cooling system which overcomes the disadvantages mentioned. In particular, a cooling system is to be made available which is based on waveguide cooling, the fluid-tight encapsulation in the area of the connection of the coolant line to the waveguide being simplified compared to the prior art. A fluid-tight encapsulation of the coolant connection that is as reliable as possible should nevertheless be ensured. Furthermore, a comparatively compact structure for the coolant connection is to be implemented in particular. Another object is to specify a component for an electrical machine with such a cooling system.

These objects are solved by the cooling system described in claim 1 and the component described in claim 10 ge. The cooling system according to the invention is a cooling system for a component of an electrical machine, the machine (and accordingly also the component) having a central machine axis A. The cooling system comprises at least one waveguide which forms a current-carrying (ie energized or energizable) part of a winding of the electrical machine and which is designed to have a liquid coolant flowing through it. The waveguide has an opening in at least one first axial end region for introducing and / or discharging coolant. The cooling system further comprises a connection element which has an internal coolant chamber which is defined by a boundary wall of the connection element. The connection element (and in particular its boundary wall) has a first opening which encloses the at least one waveguide in its first axial end region. Furthermore, the connection element (and in particular its boundary wall) has a second opening which is designed for introducing and / or discharging coolant into the internal coolant chamber. The connection element (and in particular its boundary wall) is in such a way with encapsulated in a potting compound so that the transition area, which extends from the waveguide over the inner seal to the boundary wall, is completely covered by the potting compound towards the outside environment.

The component of the electrical machine can in particular be a rotor or a stator for such an electrical machine. Alternatively, however, it can also be a transformer winding, for example, in which case a transformer is also understood to be an electrical machine in the broader sense. It is essential that the component has a winding which can be cooled with the cooling system according to the invention based on the principle of waveguide cooling. The waveguide thus fulfills a double function and serves, on the one hand, to introduce coolant into the area of the winding and, on the other hand, fulfills the function of a current-carrying conductor, which is also electrically part of the superordinate winding of the machine. So it is in particular electrically conductive with the other parts of the winding connected and inte grated as part of a higher-level coil in this. The fluidic coupling of the inner part of the waveguide to a coolant inflow and / or a coolant outflow is conveyed via the described connection element. This connection element thus acts as a type of adapter between the waveguide and a coolant supply line or a coolant discharge line. The connection element described here comprises above all the internal coolant chamber, the boundary wall and the openings described. In particular, the potting compound should not be viewed as part of the connection element, but rather it envelops it.

The first opening of the connection element serves to convey the fluidic coupling between the inner part of the Hohllei age and the coolant chamber of the connection element. For this purpose, an axial end region of the waveguide can protrude through this first opening into the coolant chamber of the connection element. Clarification should be mentioned that the described "axial end region" of the waveguide does not necessarily have to be an end piece of this conductor from an electrical point of view. It is only essential that it is a region of the waveguide which is geometrically located at an axial end of the winding and in which chem an opening for introducing and / or discharging coolant is expediently located in the waveguide or out of the waveguide. Such an end region can, for example, either actually be an end piece of the hollow conductor or it can also be one An opening can be provided in the area of this bending point, as is described, for example, in DE 102017204472 A1 for the hairpin-shaped conductor there.

Correspondingly, the second opening of the connection element serves to convey the fluidic coupling between the coolant chamber of the connection element and a superordinate coolant supply line or a coolant discharge line.

It is essential in connection with the present invention that the transition from the waveguide to the connection element is reliably encapsulated fluidically against the external environment. This reliable encapsulation is achieved by the casting compound, which completely envelops at least the transition area between the waveguide and the connection element. In the case of such an encapsulation with a potting compound, it is relatively easy to achieve a permanent, fluid-tight seal between the potting compound and the other elements, in particular between the potting compound and the boundary wall, by suitable material pairing.

In addition to this external encapsulation by means of the casting compound, the boundary wall should be sealed against the at least one waveguide via a circumferential inner seal. This seal should be "circumferential" in the sense that it closes the waveguide in a ring against the boundary wall. seals that surrounds the waveguide in the area of the first opening. The term "inner seal" refers to the fact that it is additionally covered by the potting compound from the outside environment. The function of the inner seal is to seal the interior of the connection element during the production of the cooling system (in particular during the potting step For this purpose, only a temporary fluid-tight seal of the transition between the boundary wall and the waveguide needs to be achieved by means of the inner seal. After the completion of the cooling system, the transition from the waveguide to the boundary wall of the connection element is essentially sealed by the potting compound so that it The tightness of the inner seal then no longer matters. The tightness in the area of this inner seal must therefore only be guaranteed during the casting with the potting compound. On the other hand, the tightness only has to be given with respect to the potting compound and, for example, not compared to other, especially low-viscosity liquids or even gases. Thus, the requirements for the tightness and the stability of this inner seal are relatively low, which significantly simplifies its design compared to the prior art.

Another advantage of the invention can be seen in the fact that with this embodiment a particularly long-term stable, fluid-tight encapsulation can be achieved in a relatively simple manner. This is made possible by the fact that the long-term stability of the structure described is primarily about the stability of the interface between the material of the boundary wall and the potting compound. These two materials can be selected relatively free of other boundary conditions, so that a suitable material pairing can be selected, particularly with regard to the long-term stability of this interface. In particular, no long-term stable seal against a metallic Lei termaterial is necessary, which is much more difficult to achieve with conventional sealants and potting compounds than one Sealing against electrically non-conductive materials. The present invention can therefore also be used to implement a particularly long-term stable and thus low-maintenance seal in the end region of the waveguide.

The component according to the invention is designed as a component for an elec tric machine. The component comprises an electrical winding and a cooling system according to the invention. The waveguide described above is in particular part of the cooling system (since it enables the winding to be cooled directly) and a part of the electrical winding that is energized. The advantages of the construction according to the invention result in a similar way to the advantages of the cooling system according to the invention described above.

Advantageous refinements and developments of the invention emerge from the claims dependent on claims 1 and 10 and the following description. The described configurations of the cooling system and the component can generally be advantageously combined with one another.

Thus, according to a generally advantageous embodiment, the boundary wall can be formed from a material which is different from the material of the at least one waveguide. This makes it possible in a particularly advantageous manner to select a material for the casting compound which is optimized particularly with regard to a long-term stable seal against the material of the boundary wall. In contrast, the potting compound does not have to be optimized for mapping against the typically metallic material of the waveguide. In particular, the boundary wall can be formed from a non-metallic material. The sealing by means of a potting compound against a non-metallic material is generally much easier to implement. In general, the waveguide can in particular have a metallic material, for example copper and / or an alloy containing copper. The material of the boundary wall and the material of the waveguide can particularly advantageously have different coefficients of thermal expansion. In general, it is advantageous if the thermal expansion coefficient of the casting compound is adapted to the thermal expansion coefficient of the boundary wall. This is comparatively easy to achieve, especially for a non-metallic material of the boundary wall. By adapting the thermal expansion coefficients between the casting compound and the boundary wall, the formation of cracks in the area of the corresponding interface can be avoided or at least reduced particularly effectively. It is particularly advantageous within the scope of the present invention if the long-term stability and / or the fluid tightness for the sealing compound / boundary wall interface is greater than for the sealing compound / waveguide interface. For the effective fluid-tight encapsulation, in the context of the embodiment according to the invention, the impermeability and stability of the first-mentioned interface are particularly important.

The winding of the electrical machine can generally comprise a plurality of waveguides. This plurality of waveguides can form a distributed winding, for example. For this purpose, individual waveguides can be electrically connected to one another in their axial end regions. On the other hand, all other waveguides which are not specifically connected to one another should expediently be electrically insulated from one another.

For the electrical insulation of the at least waveguide ge against the environment, it is generally advantageous if the mate rial of the boundary wall is an electrically non-conductive mate rial. However, other embodiments are also conceivable in which the boundary wall is formed from an electrically lei border material. This can be the case, for example, when the at least one waveguide is not energized. For example, one or more such non-energized waveguides can be used in an (otherwise energized) winding be interspersed in order to enable effective cooling of the winding.

According to a generally preferred embodiment, the waveguide is completely encapsulated with the potting compound in such a way that there is no exposed interface between the waveguide and potting compound which can come into contact with the external environment. This embodiment is particularly advantageous because a long-term stable, tight boundary surface between a metallic conductor and a potting compound is much more difficult to achieve than between a potting compound and a freely selectable material. It is therefore particularly preferred if the outwardly open boundary surfaces of the fluid-tight encapsulation are in particular only boundary surfaces between the potting compound and the boundary wall. By avoiding an exposed interface between the waveguide and the potting compound, it is advantageously achieved that the fluid-tight encapsulation of the internal coolant chamber is retained even if the contact between the waveguide and potting compound is broken. In other words, an interface between the waveguide and the potting compound should only exist if it does not continue anywhere to the external environment. It should therefore be closed in itself and should at most merge into an interface between the casting compound and the boundary wall.

In the context of this embodiment, it is particularly advantageous if there are no outwardly open surfaces of the waveguide at all. The waveguide is then completely encapsulated with the potting compound towards the outer environment. In particular, the waveguide can then be enclosed by the potting compound in its entire axially inner area, so that at most its axial end areas are connected to corresponding connection elements and are thus also encapsulated. These connections are in turn sealed by the potting compound, as described above.

A region of the waveguide that is open to the outside is advantageously avoided overall. It is also generally advantageous if the connection element is completely encapsulated with the potting compound in such a way that the boundary wall can only come into contact with the external environment in the area of the second opening. This embodiment leads to a particularly high fluid tightness in the area of the connection element, since the interface between the boundary wall and potting means, over which a potential leak could extend between the first opening and the external environment, is particularly long here. In this embodiment, the boundary wall is therefore encapsulated from the outside environment by means of the potting compound over all except in the area of the second opening.

Various variants are conceivable for the design of the inner seal. For example, the inner seal can be implemented by a separate sealing element which is arranged between the waveguide and the boundary wall of the connection element. For example, such a separate sealing element can be implemented by an O-ring. Alternatively, it can be a solid sealing ring. Alternatively, it can also be a ring-shaped adhesive seal, in which case the adhesive then forms the separate you telement. Generally advantageously, the material of such an additional sealing element can be an elastic plastic, in particular an elastomer, or comprise such a material. For example, the sealing element can be made of rubber.

However, the inner seal can generally also be implemented without an additional sealing element. For example, the waveguide can be temporarily sealed against the material of the boundary wall via a press seal.

According to a first advantageous embodiment variant for the inner seal, the waveguide is in direct contact with the inner seal. In this variant there is no additional element between the waveguide and the internal neren seal provided. If there is a separate sealing element, the waveguide is in direct contact with this sealing element. In this way, a particularly simple temporary seal can be achieved by means of the inner seal. This embodiment variant is particularly advantageous when only a single waveguide is connected to the connection element via the first opening.

According to an alternative, second embodiment variant for the inner seal, the waveguide is at least in a partial area in indirect contact with the inner seal in such a way that an additional connecting element provides the contact between the waveguide and the inner seal. This embodiment variant is particularly advantageous when several waveguides are coupled to the connection element via a common first opening. Several waveguides can therefore protrude through the same first opening into the connection element and there can be fluidically connected to the coolant chamber.

In this case, the connecting element described can simultaneously fulfill the function of an electrical connecting element which provides an electrical connection between two or more waveguides. In particular, two waveguides can be electrically connected to each other in this way, which form forward and return conductors of a common turn of the winding.

In this second variant, the connecting element described can also only be present in a partial area of the connection point between the waveguide and the inner seal. In particular, there can be a direct contact and an indirect contact between the waveguide and the inner seal next to one another. Optionally, however, the connecting element can also enclose the waveguide in such a way that the contact between the waveguide and the inner seal is only mediated via this connecting element. This is mainly especially the case with a ring-shaped enveloping connecting element.

According to a generally advantageous embodiment of the cooling system, the connection element can have a plurality of first openings which each enclose one or more waveguides in their axial end regions. The advantage of this embodiment is that a plurality of waveguides can be fluidically coupled to a coolant inflow line or a coolant outflow line in a particularly simple manner. In particular, several waveguides of a distributed winding can be fluidically contacted, although a comparatively simple and robust structure can still be used. One or more waveguides of the winding can thus protrude into each of the first openings. The individual first openings of the superordinate connection element can particularly advantageously be distributed over different circumferential positions of the component. In particular, the waveguides of several grooves of the component distributed over the circumference can be coupled to a coolant inflow line or coolant outflow line via the same connection element. For this coupling of several waveguides with only one connection element, in particular only a single second opening is particularly advantageous. This single second opening can therefore serve to feed coolant into a plurality of waveguides or to discharge coolant from a plurality of waveguides.

In this embodiment, it is particularly advantageous if the connection element is designed in a ring shape or has the shape of a ring segment. The inner coolant chamber of the connection element can form an annular or ring segment-shaped inner coolant channel. This coolant channel can have a plurality of first openings which are distributed over a plurality of circumferential positions of the machine. According to a generally advantageous embodiment, the material of the boundary wall can be a plastic. It can particularly advantageously be an organic polymer material, in particular a thermoplastic. Such a thermoplastic can be a filled thermoplastic, for example. Glass fiber material is particularly preferred as a filler material, for example in order to be able to set desired thermal properties. In general, the choice of a plastic material advantageously enables a particularly simple production of complex shapes of the boundary wall. Shaping by injection molding or by an additive manufacturing process can be used particularly advantageously.

The material of the potting compound can generally advantageously be a polymer or comprise such a material. Temperature-resistant casting resins, such as epoxy resins or polyurethanes, are particularly advantageous here. Such a casting resin can preferably be temperature-resistant in the cured state corresponding to thermal class F, which corresponds to a maximum permissible continuous temperature of 155 ° C. Particularly preferably, such a casting resin can even be temperature-resistant in accordance with thermal class H, which corresponds to a maximum permissible continuous temperature of 180 ° C.

According to a further generally advantageous embodiment of the cooling system, this can be a closed cooling system with a closed coolant circuit. The advantages of the invention with regard to permanent fluid-tight encapsulation are particularly effective in such a closed cooling system. However, embodiments with open coolant systems should in principle also be encompassed by the invention.

According to a generally advantageous embodiment of the construction part this can be formed out as a stator of the electrical machine. In the case of such a fixed component, the coupling of the connection element described to an over- orderly coolant inflow line or coolant outflow line is particularly easy to implement. The winding to be cooled is then a stator winding.

Alternatively, however, the component can also be, for example, a rotor of an electrical machine. The winding to be cooled is then a rotor winding. Methods are also known from the prior art for cooling such rotor windings to circulate the coolant used in particular in a closed coolant circuit in the rotating system or to transfer it between the rotating system and the stationary system.

Alternatively, however, the component can also be a component of an electrical machine, for example a transformer winding of a transformer. Here, too, the advantages of the invention in connection with the cooling of the winding come into play.

According to a further generally advantageous embodiment of the component, the winding can comprise both one or more waveguides and one or more solid conductors. In other words, the winding can be composed of different conductors. Thus, the number of waveguides can be less than the total number of conductors required for the winding. This reduces the number of inflow points or outflow points required for the coolant. Overall, the expenditure on equipment for the fluidic coupling of the individual waveguides can be reduced even further compared to a winding that is composed exclusively of waveguides. Depending on the proportion of waveguides used, effective direct cooling of the winding can still be implemented. Alternatively, however, it is generally also possible and under certain circumstances advantageous for the winding to be composed exclusively of waveguides. In this case, the maximum number of waveguides corresponds to twice the number of turns, which results in a correspondingly high number of fluidic connection points. This maximum number is given in particular when the forward conductor and the return conductor of each turn are each formed by simple hollow conductor bars. When using waveguides bent in the shape of a hairpin, on the other hand, the maximum number of waveguides corresponds exactly to the number of turns.

According to a generally advantageous embodiment, the component can have at least one first connection element which is designed as an inflow chamber for the coolant. In addition, the component can have at least one second connection element, which is designed as an outflow chamber for the coolant. The first connection element thus serves in particular to fluidically connect the at least one waveguide to a superordinate coolant inflow line. The second connection element is used accordingly to fluidically connect the at least one waveguide to an above-ordered coolant outflow line. By using two such connection elements designed according to the invention, a coupling of the at least one waveguide to a superordinate coolant circuit can thus be implemented in a relatively simple manner.

According to a first advantageous variant of this embodiment, the at least one inflow chamber and the least one outflow chamber can be arranged in part on the same axial side of the construction. In this embodiment, the shortest length of a waveguide corresponds exactly to the length of a turn. The waveguide can then be particularly advantageously designed in the shape of a hair needle. One advantage of this first variant is, for example, that one axial side of the component can remain free of coolant connections. A particularly compact structure of the component can thus be advantageous will be realized. This variant is particularly advantageous for electrical machines with a short axial length, because then only minor problems with hydraulic pressure losses occur within the waveguide.

According to an alternative, second advantageous variant, the at least one inflow chamber and the at least one outflow chamber can be arranged on opposite axial sides of the component. In this variant, the shortest possible length of a waveguide corresponds to only half a turn. This means that even shorter waveguide lengths and thus lower hydraulic pressure losses can be achieved. In this embodiment, simple waveguide rods are therefore advantageously used for each forward conductor or return conductor of the winding. This second version is to be preferred for machines with a somewhat larger axial length, in which hydraulic pressure losses play a greater role.

According to a further generally advantageous embodiment of the component, it can be composed of a number s of segments. The component can have a plurality n of connection elements, where n is either equal to 2-s or an integral multiple of 2-s. Thus, there is in particular at least one inflow chamber and one outflow chamber for each segment of the component. Generally advantageously, the number s can be a plurality of segments, so that a real segmented component is present. For example, it can be a stator or rotor of an electrical machine segmented in the circumferential direction. Alternatively, however, the number s can also be 1, so that it can in particular be a one-piece “complete stator” or “complete rotor” of an electrical machine.

The invention is described below on the basis of a few preferred exemplary embodiments with reference to the attached drawings, in which: Figure 1 shows a schematic sectional view for part of a cooling system according to a first example of the invention,

FIG. 2 shows a somewhat larger section of a similar one

Shows cooling system according to a second example of the invention,

Figure 3 shows a section of a cooling system according to a third example of the invention and Figures 4 and 5 show two axial longitudinal sections of subregions of electrical.

Identical or functionally identical elements are provided with the same reference symbols in the figures.

FIG. 1 shows a schematic sectional illustration for a partial area of a cooling system 1 of an electrical machine according to a first exemplary embodiment of the invention. The cutting plane comprises on the one hand the axial direction a (which runs parallel to the machine axis) and a second direction r. This second direction r can in principle either be a radial direction of the machine or a circumferential direction of the machine. Both geometric variants with regard to the arrangement of the elements shown here are therefore possible. In each case, the sectional plane of FIG. 3 lies at a certain radial distance from the machine axis.

The cooling system 1 is used here as a cooling system for a stator of an electrical machine. This stator comprises a stator winding, of which only two individual conductor sections are shown here as a representative, namely parts of two rod-shaped waveguides 3. Only a small portion of this waveguide is shown here, namely a first axial end region 3a. These two waveguides are guided parallel to one another in the axial end region 3a. Both have an internal cavity with an opening 4 for introducing and / or discharging coolant. The ones in the section of the Openings 4 shown in FIG. 1 are both used for feeding coolant into the waveguide. At the opposite ends of these waveguides, however, there are corresponding de, not shown here openings for discharging coolant. In order to fluidically connect the two waveguides 3 to a coolant supply of the cooling system 1, the two illustrated axial end regions 3 a are coupled to a connection element 5. This connection element 5 has an internal coolant chamber 6, from which a liquid coolant can be fed into the two waveguides 3. This is done via a first opening 5a of the connection element, which jointly encloses the two waveguides in the axial end regions. The coolant is fed into the internal coolant chamber 6 again through a second opening 5b of the connection element 5, which can be connected to a superordinate coolant inflow line, not shown here. The direction of flow of the coolant is illustrated here by arrow 12.

The internal coolant chamber 6 of the connection element 5 is defined by a boundary wall 7. This limita- tion wall is formed, for example, from an electrically non-conductive material and in particular from plastic. In this way, unwanted electrical shorts in the area of this wall are avoided. The fluid-tight sealing of the internal coolant chamber 6 from the external environment 10 is achieved in two successive stages during the manufacture of the stator. First of all, a temporary seal is created between the two waveguides 3 protruding into the opening 5a and the surrounding boundary wall 7. First, the two waveguides 3 are electrically and mechanically connected to one another via an additional connecting element 11. Such a connecting element can be, for example, a metallic contact element which surrounds the two waveguides 3 in a ring-shaped manner in the manner of a clamp. This connecting element 11 is in turn connected to the boundary wall 7 via an inner seal 8. This inner seal can be, for example, a Act on the O-ring seal. It is essential that this inner seal 8 seals the two waveguides 3 at least temporarily in a fluid tight manner against the boundary wall. In this example, the seal between the waveguide and the inner seal is also conveyed via the connecting element 11. In a second step, this temporary seal is encapsulated with a potting compound 9 in such a way that the described connection area to the external environment 10 is completely encased.

In the example of FIG. 1, the connection element is completely encapsulated with the potting compound 9 that the limiting wall 7 is only exposed in the area of the second opening 5b to the external environment 10. The boundary wall 7 continues to the right and left beyond the area shown. However, in the outlying areas not shown here, it can either be encased by the potting compound on the outside or (if the second direction r is a circumferential direction) closed in a ring shape.

In Figure 2, a slightly larger section of a similar cooling system 1 according to a second example of the invention is ge shows. Here too, a corresponds to the axial direction of the machine and the second direction r is intended to correspond to the circumferential direction of the machine for this example. The section selected here shows a partial area of a distributed winding 13, which in turn is part of a stator winding of the machine. This distributed winding is formed from multiple curved and overall hairpin-shaped waveguide segments 3, which can be configured, for example, similar to that described in DE 102017204472 A1. However, the dimensions of the individual sections are not shown true to scale and are to be understood only extremely schematically. In particular, the axially inner region 3c of these Lei tersegmente can be made much longer than the other parts. In addition, these axially inner sections in the axial area 3c can be inserted into the grooves of one here be embedded stator core, not shown. The connection element 5 is configured here overall similarly to the example in FIG. 1. It is essential for the example in FIG. 2 that the hairpin-shaped waveguide segments, apart from their first axial end regions 3a, are embedded in the potting compound 9 over their entire axial length. In the inner area 3c, in which the waveguides run in the grooves of the stator lamination stack, this stator lamination stack can in particular also be embedded in the potting compound 9 together with the Hohllei tern. In connection with this example, it is essential that the two hollow conductors are completely encapsulated with respect to the external environment 10 over their entire length. Within the cross-sectional area shown, the casting compound 9 therefore only has surfaces 9a which are exposed to the outside in the opposite axial end regions.

As already described in connection with the example of FIG. 1, the internal coolant channel 6 can continue in the circumferential direction r in both directions in the manner of a ring-shaped or ring-segment-shaped coolant channel 6a. In the shown hairpin-shaped configuration of the waveguide, the opposite end pieces, not shown here, are also arranged in the first axial portion 3a of the stator. These opposite end pieces then correspond to the coolant outlet side of the individual waveguides. They can be fluidically coupled in an analogous manner to a corresponding, similarly designed second connection element 5. The same applies to the exit side of the waveguide 3 in FIG. 1. Such a second connection element can in particular be arranged in a different radial plane than the first connection element shown here, which is provided for supplying coolant. In this way, a supply of coolant with an inflow chamber and a discharge of coolant with a corresponding outflow chamber can be implemented in the same axial end region. For this purpose, the respective second openings 5b of the individual connection elements 5 can be provided with a corresponding corresponding superordinate coolant inflow line or coolant outflow line.

FIG. 3 shows a partial area of a cooling system 1 according to a third example of the invention. Again, a sectional plane is shown which comprises an axial direction a parallel to the machine axis and the circumferential direction as a second direction r. Here, too, the cooling system has a connection element 5, which is provided for the fluidic coupling of a plurality of waveguides to a closed coolant circuit.

In this example, however, the connection element 5 shown is intended to correspond, by way of example, to an outflow chamber for the coolant, as is indicated by the direction of flow 12. An analog inflow chamber can, however, basically be constructed in the same way. The section in FIG. 3 is selected such that two first openings 5a branching off from the annular coolant channel 6a are visible. These are representative of a significantly larger number of such first openings, which can be partially distributed over the circumferential direction of the construction. In the example shown, only a single hollow conductor 3 protrudes into each of these first openings. In principle, however, it is also possible for a plurality of waveguides to be coupled to the internal coolant chamber 6 via a common first opening. The individual waveguides 3 shown are each temporarily sealed directly (that is, not via an additional connecting element) via the inner seal 8 against the surrounding boundary wall 7. Here, too, the inner seal only serves to effect a temporary seal with respect to the potting compound 9 applied in the second step. In the example of FIG. 3, the inner seal 8 is designed, for example, as a solid sealing ring and, in each case, also forms a separate sealing element here. From the seal with the potting compound, similar to the two previous examples, the final fluid-tight seal of the connection area with respect to the coolant used. The waveguides 3 shown are each electrically connected to an associated solid conductor 23, with which they can together form a turn of the winding. These Massivlei ter are also part of the winding of the machine component. However, they are not part of the cooling system, as no liquid coolant is transported through them. The direct cooling of the winding takes place here only via those selected conductor segments, which are formed as waveguides. If this is only a certain subset of the total number of conductor segments, the number of fluidic connections required can be reduced and thus the overall cooling system can be simplified.

The opposite axial end region 3b of the individual conductor segments is not shown in FIG. In principle, it can be designed similar to the example in FIG. 2, so that the conductors are particularly hairpin-shaped and form both the outgoing conductor and the return conductor of a superordinate turn via corresponding bends in the end areas 3b. Alternatively, however, it is also possible and under certain circumstances advantageous if the individual conductor segments (both the waveguides and the solid conductors) are designed as simple conductor bars. Then it is useful if a corresponding connection element 5 is also seen in the opposite axial end region 3b, which is then designed analogously to the supply of coolant tel.

In Figures 4 and 5, two general variants are shown schematically how the coupling of the already described parts of the cooling system to a superordinate coolant inflow line 47 and a superordinate coolant outflow line 48 can be implemented in the two axial end regions 3a and 3b. Shown in each case are longitudinal sections of electrical machines 41 along the machine axis A. Both figures representatively show only the portion of the inner rotor 43 and the outer stator 42 located above the machine axis A Stator 42 that component of the machine which is cooled with the cooling system according to the invention. However, this is only one possible implementation and it is alternatively also possible that the rotor of the machine is cooled in the manner according to the invention.

FIG. 4 shows an electrical machine, the stator 42 of which is cooled with a cooling system 1. This cooling system 1 has coolant connections only in one axial end region. Since this is the end region which corresponds to the first axial end region 3 a of the stator winding 44. This stator winding 44 is embedded in its axially inwardly lowing area in the grooves of a laminated stator core 45. The stator winding 44 can either only be composed of hollow conductors, similar to the examples in FIGS. 1 and 2, or it can be composed of a mixture of hollow conductors and solid conductors, similar to the example in FIG. that the stator winding comprises at least one waveguide. The one-sided fluidic coupling to the coolant circuit is made possible by the fact that the cooling system has both an inflow chamber 51 and an outflow chamber 52 at the same axial end. Each of these two chambers 51 and 52 is formed by a connection element 5 which, for example, can be configured similarly to that described in connection with FIGS. 1 to 3. In Fi gur 4 these two chambers 51 and 52 are only indicated very schematically. In particular, they are only indicated by the outline of the area 49 encapsulated with potting compound, which extends into the relevant axial end area 3a. These two chambers 51 and 52 can each be configured in a ring shape or at least have the shape of a ring segment so that they can be coupled to the waveguides at different circumferential positions. In order to avoid a spatial overlap of the two individual chambers 51 and 52 (as one might assume based on the extremely rough sketch in FIG. 4), the two individual chambers can, for example, be arranged in different radial directions Be arranged levels of the machine. Alternatively or additionally, they can also form a complex network of individual inflow channels and outflow channels that are nested in one another and are only offset from one another at individual positions in the axial, radial and / or azimuthal directions. In any case, the inflow chamber 51 is fluidically coupled to a superordinate coolant inflow line 47 and the outflow chamber 52 is coupled to a superordinate coolant outflow line 48. The position of these two lines 47 and 48 shown in FIG. 4 is also to be understood only extremely schematically. The two lines can in particular be arranged adjacent to one another in the axial direction, in the radial direction and / or in the azimuthal direction. It is only essential that they are located at the same axial end of the machine component.

FIG. 5 also shows a similar electrical machine 41, the stator 42 of which is cooled by a cooling system 1 according to the present invention. In contrast to the example of FIG. 4, however, here the coolant inflow line 47 and the coolant outflow line 48 are arranged at opposite axial ends of the stator. Here too, for connection to the coolant inflow line, an inflow chamber 51 is provided, which is formed by a connection element, as has been described above. In a similar manner, an outflow chamber 52 is provided for connection to the coolant outflow line, which is likewise formed by such a connection element. In the example of FIG. 5, however, the inflow chamber 51 and the outflow chamber 52 are arranged at different axial ends of the stator. This enables the use of simple waveguide rods, the length of which then corresponds to only half a turn of the stator winding. In this way, the length of the waveguide through which the coolant flows can be selected to be shorter overall, and the hydraulic losses can be lower. List of reference symbols

1 cooling system

3 waveguides

3a first axial end region

3b second axial end area

3c axially inner area

4 Opening of the waveguide

5 connection element

5a first opening

5b second opening

6 internal coolant chambers

6a annular coolant channel

7 boundary wall

8 inner seal

9 casting compound

9a exposed surface of the potting compound

10 external environment 11 connection element 12 flow direction 13 distributed winding

23 solid ladder

24 electrical connector

41 electric machine

42 stator

43 rotor

44 stator winding

45 stator sheet package

47 Coolant supply line

48 coolant drain line

49 encapsulated area

51 inflow chambers

52 drainage chambers A central machine axis a axial direction r second direction

Claims

1. Cooling system (1) for a component of an electrical machine with a central machine axis A, comprising

- At least one waveguide (3) which forms a current-carrying part of a winding of the electrical machine and which is designed to have a liquid coolant flowing through it, the waveguide (3) rich in at least one axial end region (3a) having an opening ( 4) for introducing and / or discharging coolant,

- At least one connection element (5) which has an internal coolant chamber (6) which is defined by a limiting wall (7) of the connection element (5),

- wherein the connection element (5) has a first opening (5a) which encloses the at least one waveguide (3) in its axial end region (3a),

- wherein the boundary wall (7) is sealed against the at least one waveguide (3) via a circumferential inner seal (8),

- wherein the connection element (5) has a second opening (5b) which is designed for introducing and / or discharging coolant into the internal coolant chamber (6),

- and wherein the connection element (5) is encapsulated with a casting compound (9) in such a way that the transition area from the waveguide (3) via the inner seal (8) to the boundary wall (7) to the external environment (10) is completely from the potting compound (9) is covered.

2. Cooling system (1) according to claim 1, wherein the limita- tion wall (7) is formed from a material which is different from the material of the at least one waveguide (3).

3. Cooling system (1) according to one of claims 1 or 2, at wel chem also the waveguide (3) so completely with the casting compound (9) is encapsulated so that there is no exposed interface between the waveguide (3) and casting compound (9) which can come into contact with the external environment (10).

4. Cooling system (1) according to one of the preceding claims, in which the connection element (5) is completely encapsulated with the potting compound (9) that the boundary wall (7) only in the area of the second opening (5b) in contact with the outer Environment (10) can occur.

5. Cooling system (1) according to one of the preceding claims, wherein the waveguide (3) is in contact directly with the inner device (8).

6. Cooling system (1) according to one of the preceding claims, in which the waveguide (3) is at least in a partial area in such indirect contact with the inner seal (8) that an additional connecting element (11) the contact between the waveguide ( 3) and the inner seal (8) mediated.

7. Cooling system (1) according to claim 6, in which a plurality of waveguides (3) protrudes into the same first opening (5a) of the connecting element (5), the additional connecting element (11) for electrical connection of the plurality of waveguides ( 3) serves.

8. Cooling system (1) according to one of the preceding claims, in which the connection element (5) has a plurality of first openings (5a) which each enclose one or more waveguides (3) in their axial end regions (3a).

9. Cooling system (1) according to one of the preceding claims, in which the material of the boundary wall (7) is a plastic.

10. Component (42) for an electrical machine (41), which has an electrical winding (44) and a cooling system (1) according to one of claims 1 to 9.

11. Component (42) according to claim 10, which is designed as a stator (42) of the electrical machine (41).

12. Component (42) according to one of claims 10 or 11, in which the winding (44) comprises both one or more Hohllei ter (3) and one or more solid conductors (23).

13. Component (42) according to one of claims 10 to 12, which has at least one first connection element (51) which is designed as an inflow chamber (51) for the coolant, and which has at least one second connection element (52), which as Outflow chamber (52) is designed for the coolant from.

14. Component (42) according to one of claims 10 to 13, in which the at least one inflow chamber (51) and the at least one outflow chamber (52) are arranged on the same axial side (3a) of the component.

15. Component (42) according to one of claims 10 to 13, in which the at least one inflow chamber (51) and the at least one outflow chamber (52) are arranged on opposite axial sides (3a, 3b) of the component.