WO2025124788A1 - Rotor for an electric machine, method for manufacturing a rotor, and electric machine - Google Patents

Abstract

The present invention relates to a rotor (1) for an electric machine (2), the rotor comprising a rotor body (4) that is equipped with a rotor winding (10) and has a laminated core (6) with polar arms (7), wherein each pair of polar arms (7) defines between them longitudinal slots (9) that extend axially through the laminated core (6). According to the invention, the rotor (1) also comprises a cooling device (14) which has cooling tubes (15) that are accommodated within the longitudinal slots (9) between adjacent longitudinal winding portions (12) of the rotor winding (10) and are arranged, at least in sections, to follow the contour of said longitudinal winding portions (12), in particular without any gaps, such that the cooling tubes (15) are fixed to the longitudinal winding portions (12) via a frictional and/or interlocking connection (16). The invention also relates to a method for manufacturing such a rotor (1) and to an electric machine (2) equipped with such a rotor (1).

Description

Rotor for an electrical machine, method for producing a rotor and electrical machine

The invention relates to a rotor according to the preamble of claim 1. The invention relates in particular to a method for producing a rotor and, further in particular, to an electrical machine having such a rotor.

A rotor for an electrical machine of the type mentioned above is described in EP 2 985 885 A1. The known rotor has a cooling device with cooling tubes through which coolant flows for cooling longitudinal sections of a rotor winding. The challenge with the present cooling concept is to securely mount the cooling tubes on the rotor against the loads that occur during operation.

The invention therefore aims to provide an improved or at least a different embodiment of a rotor for an electrical machine. In particular, the attempt is made to secure the cooling tubes to the rotor in a manner that is improved compared to the known solution. Furthermore, a method for producing a rotor and, more particularly, an electrical machine with such a rotor are to be provided.

In the present invention, this object is achieved in particular by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims and the description.

The inventors have recognized that the cooling pipes can be moved, for example, by means of Internal high-pressure forming can be mechanically fixed at least in sections in a force-locking and/or form-locking manner to longitudinal winding sections of a rotor winding of the rotor.

For this purpose, a rotor for an electrical machine is proposed, which comprises a rotor body defining a center of rotation, a rotor winding, and a cooling device. The rotor body has a rotor shaft aligned coaxially with the center of rotation and a laminated core arranged on the rotor shaft in a rotationally fixed manner and having a plurality of pole arms projecting radially away from the center of rotation. The pole arms are adjacent to one another in a circumferential direction around the center of rotation and define longitudinal grooves between them in the circumferential direction, which extend completely axially through said laminated core. The longitudinal grooves can, for example, be designed in the form of a V-shaped longitudinal slot pointing towards the center of rotation and/or be open radially outwards to the environment via a longitudinal opening. Said rotor winding can be energized and is made of at least one electrically conductive conductor guided in several turns around said pole arms. The at least one electrically conductive conductor can have an insulating coating to prevent incorrect electrical contact. The rotor winding further comprises axially extending winding sections, in particular parallel to the rotational center axis, which are arranged within the longitudinal slots at least in sections or over their entire surface and optionally exclusively on circumferential surfaces of adjacent pole arms that are opposite one another in the circumferential direction. The cooling device comprises cooling tubes through which coolant can flow, which are designed to cool the winding longitudinal sections. It can be provided that each longitudinal slot is assigned a cooling tube, so that the number of cooling tubes corresponds to the number of longitudinal slots. It is essential that the cooling tubes are arranged within the longitudinal slots between circumferentially adjacent longitudinal winding sections and are arranged at least in sections following the contour, in particular without gaps, on these longitudinal winding sections, so that the cooling tubes are fixed to the longitudinal winding sections in a force-fitting and/or form-fitting connection.

The cooling tubes are thus fixed in place to the longitudinal sections of the rotor winding. The resulting force-locking and/or positive connection between the cooling tubes and the longitudinal sections of the winding results in a mechanically highly resilient arrangement that can withstand even the high loads that occur during normal operation of the rotor, in particular circumferential and radial accelerations. Furthermore, auxiliary materials such as adhesives and/or thermally conductive materials, in particular thermal pastes, can be completely dispensed with, making the assembly of the proposed rotor more cost-effective and less complex in terms of process technology compared to known rotors. This provides a significant economic advantage, particularly in the industrial production of electrical machines equipped with such a rotor. The contour-following, i.e. gap-free, arrangement of the cooling tubes on the longitudinal winding sections and the simultaneous absence of auxiliary materials also ensures that a heat path through a wall of the cooling tubes is relatively short, thereby improving the transfer of thermal energy from the longitudinal winding sections to a coolant flowing through the cooling tubes.

The fact that the cooling tubes are arranged "contour-following on these winding longitudinal sections" is understood in the present invention in particular to mean that the cooling tubes are designed in such a way that they are supported on the winding longitudinal sections without gaps. Accordingly, the outer surfaces of the cooling tubes can be directly connected to the windings of the rotor winding. The cooling tubes can preferably be machined in such a way that they follow a surface contour of the winding longitudinal sections without a gap, whereby the cooling tubes, so to speak, mold the surface contour of the winding longitudinal sections and, at least in some areas, have a toothing contour as mentioned below.

The fact that the cooling tubes are "accommodated within the longitudinal grooves between circumferentially adjacent longitudinal winding sections" is to be understood, in the context of the present invention, in particular to mean that the cooling tubes are arranged entirely or at least partially within the longitudinal grooves. Cooling tubes arranged entirely within the longitudinal grooves expediently do not protrude upwards through the longitudinal openings of the longitudinal grooves to the surroundings. Furthermore, cooling tubes arranged at least partially within the longitudinal grooves expediently protrude upwards through the longitudinal openings of the longitudinal grooves to the surroundings.

The said coolant can conveniently be realized by a cooling liquid.

The said laminated core is expediently made of a plurality of laminated elements made of a ferromagnetic material stacked on top of one another in the direction of the rotational center axis.

In particular, it can be provided that the cooling tubes are arranged by means of internal high-pressure forming, at least in sections, contour-following, in particular gap-free, on the longitudinal winding sections. The cooling tubes can have a wall thickness of less than or equal to 1 mm, at least in sections. Internal high-pressure forming processes are relatively easy to master from a process engineering perspective. Cooling tubes can be installed cost-effectively and without the use of environmentally hazardous substances, following the contours of the windings. Furthermore, the relatively thin wall thickness of the cooling tubes facilitates the transfer of thermal energy between the windings and the coolant flowing through the cooling tubes, as the heat path through the cooling tubes is correspondingly shortened.

Furthermore, the rotor winding can form winding heads on axially opposite axial end faces of the pole arms, to which the longitudinal winding sections of the rotor winding are axially connected. It is conceivable that the proposed cooling tubes are also arranged at least in sections on the winding heads of the rotor winding, following the contours, in particular without gaps. This can be expediently achieved by arranging the cooling tubes at least in sections on the winding heads, following the contours, in particular without gaps, by means of internal high-pressure forming. The cooling tubes are thus positioned against the winding heads, so that cooling can also be achieved there.

During the manufacture of the rotor winding, cavities can be formed between the turns of the rotor winding and/or between the turns of the rotor winding and the pole arms. These cavities between the turns of the rotor winding and/or between the turns of the rotor winding and the pole arms can be filled with a potting compound. The potting compound used can have a predetermined thermal conductivity so that the potting compound improves the efficiency of the transfer of thermal energy from the rotor winding to the coolant flowing through the cooling tubes. In addition, the potting compound can be designed to have an electrically insulating effect. The potting compound can be a resin material, for example. It can expediently be provided that the cooling tubes are further arranged at least partially contour-following, i.e. in particular at least partially gap-free, on the opposing circumferential surfaces of the immediately adjacent pole arms, i.e. the pole arms immediately adjacent in the circumferential direction. This can expediently be achieved by arranging the cooling tubes at least partially contour-following, in particular gap-free, on the circumferential surfaces by means of internal high-pressure forming. This also provides a force-fitting and/or form-fitting connection between the cooling tubes and the pole arms, so that the cooling tubes are also fixed in place on the rotor body. This has the advantage that the cooling tubes can be even better protected against the loads occurring during normal operation of the rotor, in particular circumferential and radial accelerations.

It can also be expediently provided that the cooling tubes are arranged on radially outward-oriented root surfaces of the rotor body in a manner that follows the contour at least in part, i.e. in particular without a gap at least in part. This can expediently be achieved by arranging the cooling tubes on the root surfaces by means of internal high-pressure forming in a manner that follows the contour at least in part, in particular without a gap. The root surfaces of the rotor body are expediently designed such that they connect the opposing circumferential surfaces of pole arms that are immediately adjacent in the circumferential direction. The cooling tubes are thereby fixed in place on the root surfaces of the rotor body in a force-fitting and/or form-fitting connection. Due to the additional connection, the cooling tubes can be even better protected against the loads that occur during normal operation of the rotor, in particular circumferential and radial accelerations. Furthermore, it can be provided that the pole arms have pole shoes on the radial outside which project beyond the longitudinal slots and the longitudinal winding sections in the circumferential direction. In order to be able to protect the cooling tubes even better against the loads occurring during normal operation of the rotor, in particular circumferential and radial accelerations, it can be provided that the cooling tubes are arranged at least in sections so as to follow the contour, i.e. in particular at least in sections without a gap, on radially inwardly oriented inner surfaces of the pole shoes. This can expediently be achieved in that the cooling tubes are applied to the said inner surfaces by means of internal high pressure forming, at least in sections so as to follow the contour, in particular without a gap. The cooling tubes are thus fixed in place on the pole shoes of the rotor body in a force-fitting and/or form-fitting connection. The pole shoes have outer surfaces oriented radially outwards.

The cooling tubes can furthermore be machined such that they each have a radially outward-oriented head surface. The head surfaces of the cooling tubes can be flat or curved. The head surfaces can furthermore be arranged on and/or bear against outer surfaces of pole pieces that are immediately adjacent in the circumferential direction. Furthermore, the head surfaces can project radially beyond the outer surfaces at least in sections and/or overlap the outer surfaces at least in sections in the circumferential direction. As a result, the aforementioned longitudinal openings of the longitudinal grooves, which are open to the environment, are sealed in a fluid-tight manner by the cooling tubes and, moreover, the cooling tubes are even better secured to the rotor body.

Furthermore, it can be expediently provided that the cooling pipes each Have contact surfaces via which the cooling tubes are supported within the longitudinal grooves on the circumferentially adjacent longitudinal winding sections. This creates a surface contact between the longitudinal winding sections and the cooling tubes. Compared to merely point or linear contact, such surface contact enables a relatively efficient transfer of thermal energy between the longitudinal winding sections and a coolant flowing through the cooling tubes.

It can be expediently provided that the cooling tubes have a toothed contour in the region of the contact surfaces. By means of a corresponding toothed contour, a particularly secure force-locking and/or positive-locking connection can be created between the cooling tubes and the longitudinal winding sections. The toothed contour of the cooling tubes can expediently be formed by molding one or more superimposed layers of essentially parallel sections of the electrically conductive conductor of the longitudinal winding sections.

In particular, it can be provided that the contact surfaces are the same size or smaller than a respective longitudinal winding section in a depth direction running transversely with respect to the rotational center axis and in a longitudinal direction running parallel to the rotational center axis and transversely with respect to the depth direction. In other words, the cooling tubes are either formed over the entire surface of an available longitudinal winding section or only partially on an available surface of a longitudinal winding section. This allows a heat flow during the transfer of thermal energy between the longitudinal winding sections and the cooling tubes to be specifically specified, thus enabling an adjustment of the cooling capacity provided by the cooling device. In this context, it can be provided that the contact surfaces have a depth surface length in the depth direction and a longitudinal surface length in the longitudinal direction. It is provided that the longitudinal surface length of the contact surfaces corresponds to a longitudinal surface length of a respective longitudinal winding section running in the longitudinal direction. Furthermore, it is provided that the depth surface length of the contact surfaces corresponds to a surface length of a respective longitudinal winding section running in the depth direction. In other words, the cooling tubes extend completely over the longitudinal winding sections in the depth direction and in the longitudinal direction. The transfer of thermal energy is thus realized with a comparatively large heat flow. Alternatively, it can be provided that the depth surface length of the contact surfaces is smaller than a surface length of the respective longitudinal winding section running in the depth direction.

In particular, it can be provided that the pole arms have pole shoes on the radial outside, which project beyond the longitudinal slots and the winding longitudinal sections in the circumferential direction. The cooling tubes can be arranged at least in sections in a contour-following manner, i.e. in particular at least in sections without a gap, on radially inwardly oriented inner surfaces of the pole shoes, wherein the depth surface length of the contact surfaces, starting from the pole shoes, amounts to a maximum of 50% of a surface length of the respective winding longitudinal section running in the depth direction. For example, the cooling tubes can be arranged in a radially outer half of the rotor body or in a radially outer third of the rotor body. As a result, the contact surfaces are reduced in size compared to the contact surfaces of the previous embodiment. This has the advantage that relatively small, cost-effective cooling tubes can be used to manufacture a rotor. The assembly of the smaller cooling tubes can be comparatively simple and the overall weight of the proposed rotor can be reduced.

It can be expediently provided that the cooling tubes have fins designed to transfer thermal energy and to stiffen the cooling tubes. It is expedient if the cooling tubes each delimit an internal volume and have an inner surface facing the internal volume, wherein the fins are each arranged within an internal volume and on a respective inner surface around which coolant can flow. It can be provided that the inner surface of a cooling tube has surface sections opposite one another in the circumferential direction, on each of which at least one fin, two fins, or several fins are arranged. The fins are designed such that they lie directly opposite one another in pairs in the circumferential direction or such that adjacent fins are radially offset from one another in the circumferential direction. By means of the proposed fins, the cooling tubes can be stiffened against loads occurring during normal operation of the proposed rotor, in particular circumferential and radial accelerations. This makes it possible, in particular, to avoid undesired deformation of the cooling tubes. Furthermore, the proposed fins increase the surface area of a cooling tube involved in the transfer of thermal energy, resulting in a comparatively efficient transfer of thermal energy. Furthermore, cooling tubes with fins arranged in pairs directly opposite one another in the circumferential direction, as well as cooling tubes in which adjacent fins are radially offset from one another in the circumferential direction, can be provided cost-effectively, for example, in an extrusion process as an extruded profile.

Furthermore, the cooling pipes, where adjacent pipes are located in the direction of travel, The fins are radially offset from one another and, in an uninstalled state, are designed so that the fins interlock like a zipper. This has the advantage that the cooling tubes, referred to as tube blanks in their uninstalled state, have a relatively narrow tube cross-section. This makes it relatively easy to insert the corresponding tube blanks into the longitudinal grooves of the rotor.

It can be advantageous for the cooling tubes to be made of a non-magnetizable metal. This can preferably be an aluminum material or a steel material, more preferably stainless steel. Such cooling tubes can be provided cost-effectively, and the ductile material properties also offer sufficient formability, allowing them to be machined, particularly by internal high-pressure forming.

It is also possible for the cooling tubes to be realized using cost-effective extruded profiles. It is also conceivable for the rotor shaft to be realized using a hollow rotor shaft.

According to a further basic idea of the invention, a method for producing a rotor, in particular the rotor according to the above description, is proposed. The proposed method is characterized by the following steps:

1) Inserting tube blanks into the longitudinal groove of a rotor body equipped with a rotor winding, so that the tube blanks are accommodated within the longitudinal grooves between adjacent longitudinal winding sections of the rotor winding in a circumferential direction around a rotational center axis of the rotor body,

2) Internal high pressure forming of the tube blanks, in such a way that the tube blanks form cooling tubes which, at least in sections, follow the contour, in particular are arranged gap-free on adjacent winding longitudinal sections in the circumferential direction in a force-locking and/or form-locking connection on the winding longitudinal sections.

This provides an advantageous method by means of which a rotor according to the invention with a cooling device for cooling the longitudinal winding sections of the rotor winding can be provided cost-effectively and in large quantities.

According to a further basic idea of the invention, an electric machine, in particular a traction drive for an electric vehicle, is provided, which has a stator and a rotor designed according to the preceding description or a rotor manufactured according to the preceding method.

In summary, the present invention preferably relates to a rotor for an electrical machine, comprising a rotor body equipped with a rotor winding, which has a laminated core with pole arms, wherein adjacent pole arms define longitudinal slots between them, which axially penetrate the laminated core. It is essential for the invention that the rotor further comprises a cooling device having cooling tubes which are received within the longitudinal slots between adjacent longitudinal winding sections of the rotor winding and are arranged at least in sections in a contour-following manner, in particular without a gap, on these longitudinal winding sections, so that the cooling tubes are fixed to the longitudinal winding sections in a force-fitting and/or form-fitting connection. The invention further expediently relates to a method for producing such a rotor and, in particular, to an electrical machine equipped with such a rotor.

Further important features and advantages of the invention result from the Subclaims, from the drawings and from the associated description of the figures based on the drawings.

It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

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

They show, schematically

Fig. 1 shows a sectional view of a section of a rotor for an electrical machine according to a first preferred embodiment,

Fig. 2 shows a sectional view of the rotor from Fig. 1 during its manufacture according to the method for manufacturing a rotor according to the invention,

Fig. 3 shows a sectional view of a section of a rotor for an electrical machine according to a further preferred embodiment,

Fig. 4 shows a sectional view of the rotor from Fig. 3 during its manufacture according to the method according to the invention for producing a Rotors,

Fig. 5 shows a sectional view of a section of a rotor for an electrical machine according to a further preferred embodiment,

Fig. 6 shows a perspective view of a section of a pipe blank in an unassembled state, which can form the cooling pipe of Fig. 5,

Fig. 7 shows a sectional view of a section of a rotor for an electrical machine according to a further preferred embodiment and finally

Fig. 8 shows a perspective view of a section of another tube blank in an unassembled state, which can form the cooling tube of Fig. 7.

Figures 1, 3, 5 and 7 each show a preferred embodiment of a rotor, designated as a whole by the reference number 1, for an electric machine 2. The electric machine 2 can be designed in particular as a traction drive for an electric vehicle (not illustrated).

Fig. 1 shows a sectional view of a section of a rotor 1 for an electrical machine 2. The rotor 1 initially has a rotor body 4, which is usually approximately circularly cylindrical and defines a rotational center axis 3, around which the rotor body 4 is rotatably adjustable in a circumferential direction 8, indicated by an arrow in Figs. 1, 3, 5 and 7. The rotor body 4 has a a rotor shaft 5, which is aligned coaxially with the rotational center axis 3 and only partially indicated, which in this case is realized as a hollow rotor shaft, and a laminated core 6 arranged on the rotor shaft 5 with a plurality of pole arms 7 projecting radially away from the rotational center axis 3. The laminated core 6 consists purely by way of example of a plurality of laminated elements made of a ferromagnetic material, which are not visible in the present figures and are stacked axially one on top of the other in the direction of the rotational center axis 3.

In Fig. 1, it can also be seen that each two pole arms 7 directly adjacent to one another in the circumferential direction 8 define an approximately V-shaped longitudinal groove 9 between them in the circumferential direction 8, which extends axially through the laminated core 6. The pole arms 7 also have pole shoes 18 on the radial outside, which have an outer surface 20 on the radial outside and which project beyond the longitudinal grooves 9 at least in sections in the circumferential direction 8, so that they each form inner surfaces 19 facing the longitudinal grooves 9 and oriented radially inward towards the center axis of rotation 3.

The rotor 1 further comprises a rotor winding 10, which can be supplied with current by means of a power source (not shown), which is realized from at least one electrically conductive conductor 37. The at least one electrically conductive conductor 37 can have an insulating coating to prevent faulty electrical contact. Furthermore, it is provided that the at least one electrically conductive conductor 37 of the rotor winding 10 is guided in a conventional manner in several turns 11 around the pole arms 7, wherein the rotor winding 10 forms winding heads (also not shown) on axially opposite, not illustrated axial end faces of the pole arms 7, to which longitudinal winding sections 12 of the rotor winding 10 are connected axially, in this case parallel to the rotational center axis 3. Two of these longitudinal winding sections 12 of the rotor winding 10 are, as can be seen in Figs. 1 to 5 and 7, received within a longitudinal groove 9 and arranged at least in sections and possibly exclusively on circumferential surfaces 13 of the directly adjacent pole arms 7, which are opposite one another in the circumferential direction 8. The winding longitudinal sections 12 of the rotor winding 10 bear, for example, directly against the circumferential surfaces 13 of the pole arms 7 and each extend radially with respect to the center of rotation 3 between one of the said inner surfaces 19 of the pole shoes 18 and a radially outwardly oriented base surface 17 of the rotor body 4, which connect circumferential surfaces 13 of a longitudinal groove 9, which are opposite one another in the circumferential direction 8. A respective winding longitudinal section 12 can bear against the inner surface 19 of a pole shoe 18 and/or a base surface 17 of the rotor body 4.

During normal operation of the rotor 1, losses in the form of waste heat occur within the rotor winding 10, which cause undesired heating of the rotor winding 10 and the adjacent components of the rotor 1, in particular the rotor body 4.

In order to prevent the risk of overheating of the rotor 1 during normal operation, which could in particular lead to thermal failure of the aforementioned insulation coating of the electrically conductive conductor 37 and a failure of the electrical machine 2, provision is made for the rotor 1 to be equipped with a cooling device 14, which has cooling tubes 15 through which coolant can flow for cooling the longitudinal winding sections 12. The cooling tubes 15 are here made of a non-magnetizable, formable metal, preferably an aluminum material or a steel material, in particular stainless steel, and are furthermore designed to be formed by means of internal high-pressure forming. In Figs. 1 to 5 and 7, it can be seen that the cooling tubes 15 are accommodated within the longitudinal grooves 9 between longitudinal winding sections 12 adjacent in the circumferential direction 8. and are arranged, for example, by means of internal high-pressure forming, at least in sections in a contour-following manner, in particular without gaps, on the longitudinal winding sections 12. As a result, the cooling tubes 15 in the region of the longitudinal winding sections 12 have, at least in sections, a wall thickness of less than or equal to 1 mm. Furthermore, this creates a force-fitting and/or form-fitting connection 16 between the cooling tubes 15 and the longitudinal winding sections 12, by means of which the cooling tubes 15 are fixedly fixed to the rotor body 4 or the rotor winding 10.

In Fig. 1, it can also be seen that the cooling tubes 15 are each supported on the longitudinal winding sections 12 via contact surfaces 21. This provides a planar contact between the longitudinal winding sections 12 and the cooling tubes 15, which, compared to a point or linear contact point, allows for a relatively efficient transfer of thermal energy between the longitudinal winding sections 12 and a coolant flowing through the cooling tubes 15.

In Fig. 1, it can also be seen that, as a result of the internal high-pressure forming, the cooling tubes 15 have molded a surface contour of the winding longitudinal sections 12 in the region of the contact surfaces 21, which surface contour is expediently formed by one or more superimposed layers of sections of the electrically conductive conductor 37 that run essentially parallel to one another, so that they each have a toothed contour 22 in the region of the contact surfaces 21. This significantly improves the force-fitting and/or form-fitting connection 16 between the cooling tubes 15 and the winding longitudinal sections 12.

Furthermore, the cooling tubes 15 according to the embodiment illustrated in Fig. 1 are contour-following at least in sections by means of internal high-pressure forming, ie in particular at least partially gap-free, on the circumferential surfaces 13 of the pole arms 7 directly adjacent in the circumferential direction 8, which are opposite one another in the circumferential direction 8. As a result, the cooling tubes 15 are also fixed to the pole arms 7 in a force-fitting and/or form-fitting manner. Furthermore, the cooling tubes 15 shown in Fig. 1 are arranged by means of internal high-pressure forming in a contour-following manner, at least in sections, i.e. in particular at least partially gap-free, both on the said base surfaces 17 of the rotor body 4 and on the inner surfaces 19 of the pole shoes 18, which furthermore completely project beyond the longitudinal winding sections 12 in the circumferential direction 8. As a result, the cooling tubes are also arranged in a force-fitting and/or form-fitting manner on the base surfaces 17 and the inner surfaces 19.

Furthermore, with regard to the embodiment illustrated in Fig. 1, it should be mentioned that the contact surfaces 21 are designed to be the same size as a respective longitudinal winding section 12 in a depth direction 23 running transversely with respect to the center axis of rotation 3 and in a longitudinal direction 24 running parallel with respect to the center axis of rotation 3 and transversely with respect to the depth direction 23. Accordingly, the contact surfaces 21 have a depth surface length 25 in the depth direction 23 and a longitudinal surface length (not illustrated in the figures) in the longitudinal direction 24. The longitudinal surface length is identical to a longitudinal surface length of a respective longitudinal winding section 12 running in the longitudinal direction 24. Furthermore, the depth surface length 25 is identical to a surface length 29 of a respective longitudinal winding section 12 running in the depth direction 23. As a result, a maximum heat flow can be achieved during the transfer of thermal energy between the winding longitudinal sections 12 and a coolant flowing through the cooling tubes 15, so that an optimal cooling performance of the cooling device 14 is provided. Furthermore, it can be seen in Fig. 1 that the proposed cooling tubes 15 are designed such that they each have a head surface 36 oriented radially outwards. The head surfaces 36 of the cooling tubes 15 are flat according to the embodiments shown in Figs. 1 and 3 and curved radially outwards according to the embodiments shown in Figs. 5 and 7. The head surfaces 36 lie on outer surfaces 20 of pole pieces 7 that are immediately adjacent in the circumferential direction 8 and project radially beyond the outer surfaces 20 at least in sections. Furthermore, it can be provided that the head surfaces 36 overlap the outer surfaces 20 in the circumferential direction 8 at least in sections. As a result, the longitudinal grooves 9, which are open to the environment via longitudinal openings, are sealed fluid-tight by the cooling tubes 15.

Fig. 2 shows a sectional view of the rotor 1 from Fig. 1 during manufacture, i.e. in an unassembled state. As part of the indicated manufacture of the rotor 1, it is provided that the above-described rotor body 4 is provided with the rotor winding 10 attached thereto. Subsequently, tube blanks 35 are inserted radially through longitudinal openings of the longitudinal grooves 9 into the longitudinal grooves 9, so that the tube blanks 35 are received within the longitudinal grooves 9 between longitudinal winding sections 12 of the rotor winding 10 that are adjacent in the circumferential direction 8. The tube blanks 35 can already be supported on the longitudinal winding sections 12 of the rotor winding 10 in a point-like or linear manner. Subsequently, the tube blanks 35 are arranged by means of internal high-pressure forming, at least in sections following the contour, in particular without gaps, on winding longitudinal sections 12 adjacent in the circumferential direction 8, so that between the tube blanks 35 then referred to as cooling tubes 15 and the winding longitudinal sections 12 a force-fitting and/or form-fitting connection 16, in particular a Toothing contour 22. The tube blank 35 shown in Fig. 2 has a tube cross-section that is approximately in the shape of a figure eight. This allows the tube blank 35 to be inserted relatively easily through the longitudinal opening of the longitudinal groove 9 into the longitudinal groove 9 and, if necessary, guided to the base surface 17 of the rotor body 4. The tube blanks 35 can be realized, for example, using a cost-effectively available extruded profile.

Fig. 3 shows a sectional view of a section of a rotor 1 for an electrical machine 2 according to another preferred embodiment. In contrast to the cooling tubes 15 of the previously described embodiment, the cooling tubes 15 are designed to be relatively small. This is achieved in the present case by arranging the cooling tubes 15 at least partially contour-following, i.e., in particular, at least partially gap-free, on the inner surfaces 19 of the pole pieces 18 and by shortening the depth surface lengths 25 of the contact surfaces 21 such that the depth surface lengths 25, starting from the pole pieces 18, amount to a maximum of 50% of a surface length 29 of the respective longitudinal winding section 12 running in the depth direction 23. Furthermore, in the present embodiment, the cooling tubes 15 bear neither against the circumferential surfaces 13 of the pole arms 7, which are opposite in the circumferential direction 8, nor against the base surfaces 17 of the rotor body 4. For example, the cooling tubes 15 are arranged in a radially outer half of the rotor body 4 or in a radially outer third of the rotor body 4. As a result, the contact surfaces 21 of the cooling tubes 15 are relatively small compared to the contact surfaces 21 of the previously described cooling tubes 15 of the previous embodiment. This has the advantage that the present cooling tubes 15 are relatively small and lightweight, which, for example, can simplify their assembly.

In Fig. 4 is a sectional view of the device being manufactured, ie in a 3 in its unassembled state. In the context of the indicated production of the rotor 1, in contrast to the procedure explained for Fig. 2, it is provided that the tube blanks 35 have a polygonal tube cross-section, in particular a triangular tube cross-section. This allows the tube blanks 35 to be easily inserted through the longitudinal openings of the longitudinal grooves 9 into the longitudinal grooves 9. The tube blank 35 shown can, for example, be a cost-effectively available extruded profile.

Fig. 5 shows a sectional view of a section of a rotor 1 for an electrical machine 2 according to a further preferred embodiment. The illustrated embodiment of the rotor 1 differs from the previous embodiments of the rotor 1 in particular in that the cooling tubes 15 have integral ribs 30, which are designed to transfer thermal energy and to stiffen the cooling tubes 15. It can be seen in Fig. 5 that the cooling tubes 15 each delimit an inner volume 31 and have an inner circumferential surface 32 facing the inner volume 31 and wettable by the coolant. The said ribs 30 are arranged within the inner volume 31 on the inner circumferential surface 32, so that they are surrounded by coolant during normal operation of the rotor 1. It can also be seen that the inner circumferential surface 32 has two planar surface sections 33a, 33b lying opposite one another in the circumferential direction 8. In this case, two ribs 30 are arranged on each of the first surface portion 33a and the second surface portion 33b, wherein in the present embodiment, these ribs 30 are arranged directly opposite one another in pairs in the circumferential direction 8. By means of the proposed ribs 30, the cooling tubes 15 can be stiffened against loads occurring during the intended operation of the proposed rotor 1, in particular circumferential and radial accelerations. Undesirable deformations of the cooling tubes 15 can thus be avoided. Furthermore, by means of the proposed ribs 30, the surface area of a cooling tube 15 involved in the transfer of thermal energy is increased to such an extent that a comparatively efficient transfer of thermal energy can be achieved.

Fig. 6 shows a perspective view of a section of a tube blank 35 in an unassembled state, which forms a cooling tube 15 from Fig. 5. The illustrated tube blank 35 can be realized, for example, by an extruded profile that can be provided inexpensively.

Furthermore, Fig. 7 shows a sectional view of a section of a rotor 1 for an electrical machine 2 according to a further preferred embodiment. The illustrated embodiment of the rotor 1 differs from the embodiment of the rotor 1 according to Fig. 5 in that the ribs 30 arranged on the first surface section 33a are radially offset from one another with respect to the ribs 30 arranged on the second surface section 33b. This makes it possible to provide a compact tubular blank 35, as illustrated in Fig. 8, in which, in the uninstalled state, the ribs 30 adjacent in the circumferential direction 8 engage with one another like a zipper. The tubular blanks 35 are therefore relatively compact and have a relatively narrow construction, so that they can be inserted comparatively easily into the longitudinal grooves 9 of the rotor 1.

Finally, Fig. 8 shows a perspective view of a section of the tube blank 35 described in the previous section in an unassembled state, so that it can be seen that the ribs 30 adjacent in the circumferential direction 8 engage with each other like a zipper. After internal high-pressure forming, the tube blank 35 forms the cooling tube from Fig. 7. Furthermore, it is advantageous if the tube blank 35 shown is cost-effectively available extruded profile is realized.

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Claims

Claims 1. Rotor (1 ) for an electrical machine (2), - with a rotor body (4) defining a rotational center axis (3), which has a rotor shaft (5) aligned coaxially with the rotational center axis (3) and a laminated core (6) arranged on the rotor shaft (5) in a rotationally fixed manner and having a plurality of pole arms (7) projecting radially away from the rotational center axis (3), - wherein the pole arms (7) are adjacent to one another in a circumferential direction (8) around the rotational center axis (3) and define longitudinal grooves (9) between them in the circumferential direction (8), which axially penetrate the laminated core (6), - with an energizable rotor winding (10) comprising at least one electrically conductive conductor guided in several turns (11) around the pole arms (7), - wherein the rotor winding (10) has axially extending winding longitudinal sections (12) which are arranged within the longitudinal slots (9) at least in sections on circumferential surfaces (13) of adjacent pole arms (7) opposite one another in the circumferential direction (8), - with a cooling device (14) which has cooling tubes (15) through which coolant can flow to cool the longitudinal winding sections (12), characterized in that - the cooling tubes (15) are received within the longitudinal grooves (9) between longitudinal winding sections (12) adjacent in the circumferential direction (8) and are arranged at least in sections following the contour of the respective longitudinal winding sections (12), so that the cooling tubes (15) are fixed to the longitudinal winding sections (12) in a force-fitting and/or form-fitting connection (16). 2. Rotor (1) according to claim 1, characterized in that - the cooling tubes (15) are arranged at least in sections following the contour of the circumferential surfaces (13) of adjacent pole arms (7) opposite one another in the circumferential direction (8). 3. Rotor (1) according to claim 1 or 2, characterized in that - the cooling tubes (15) are arranged at least in sections following the contour on base surfaces (17) of the rotor body (4) which are oriented radially outwards and connect opposite circumferential surfaces (13) of adjacent pole arms (7) to one another. 4. Rotor (1) according to one of the preceding claims, characterized in that - the pole arms (7) have radially outer pole shoes (18) which project beyond the longitudinal slots (9) and the longitudinal winding sections (12) in the circumferential direction (8), - wherein the cooling tubes (15) are arranged at least in sections following the contour of radially inwardly oriented inner surfaces (19) of the pole shoes (18). 5. Rotor (1) according to one of the preceding claims, characterized in that - the cooling tubes (15) each have contact surfaces (21) via which the cooling tubes (15) are supported within the longitudinal grooves (9) on the winding longitudinal sections (12) adjacent in the circumferential direction (8). 6. Rotor (1) according to claim 5, characterized in that - the cooling tubes (15) have a toothed contour (22) in the region of the contact surfaces (21). 7. Rotor (1) according to claim 5 or 6, characterized in that - the contact surfaces (21) are equal to or smaller than a respective longitudinal winding section (12) in a depth direction (23) running transversely with respect to the rotational center axis (3) and in a longitudinal direction (24) running parallel with respect to the rotational center axis (3) and transversely with respect to the depth direction (23). 8. Rotor (1) according to claim 7, characterized in that - the contact surfaces (21) have a depth surface length (25) in the depth direction (23) and a longitudinal surface length in the longitudinal direction (24), - wherein the longitudinal surface length of the contact surfaces (21) corresponds to a longitudinal surface length of a respective winding longitudinal section (12) extending in the longitudinal direction (24), - wherein the depth surface length (25) of the contact surfaces (21) corresponds to a surface length (29) of a respective winding longitudinal section (12) extending in the depth direction (23), or - wherein the depth surface length (25) of the contact surfaces (21) is smaller than a surface length (29) of the respective winding longitudinal section (12) extending in the depth direction (23). 9. Rotor (1) according to claim 7 or 8, characterized in that - the pole arms (7) have radially outer pole shoes (18) which project beyond the longitudinal slots (9) and the longitudinal winding sections (12) in the circumferential direction (8), - wherein the cooling pipes (15) are arranged at least in sections following the contour of radially inwardly oriented inner surfaces (19) of the pole shoes (18), - wherein the depth surface length (25) of the contact surfaces (21) starting from the pole shoes (18) is a maximum of 50% of a surface length (29) of the respective longitudinal winding section (12) running in the depth direction (23). 10. Rotor (1) according to one of the preceding claims, characterized in that - the cooling tubes (15) have fins (30) which are designed to transfer thermal energy and to stiffen the cooling tubes (15). 11. Rotor (1) according to claim 10, characterized in that - the cooling tubes (15) each define an internal volume (31) and have an inner surface (32) facing the internal volume (31), - wherein the ribs (30) are arranged within the inner volume (31) on the inner surface (32). 12. Rotor (1) according to claim 11, characterized in that - the inner circumferential surface (32) has surface sections (33a, 33b) opposite one another in the circumferential direction (8), on each of which at least one rib (30), two or more ribs (30) are arranged such that - the ribs (30) are located directly opposite each other in pairs in the circumferential direction (8), or - adjacent ribs (30) in the circumferential direction (8) are radially offset from one another. 13. Rotor (1) according to one of the preceding claims, characterized in that - the cooling tubes (15) are arranged at least in sections by means of internal high-pressure forming in a contour-following manner on the longitudinal winding sections (12) and/or at least in sections have a wall thickness of less than or equal to 1 mm. 14. A method for producing a rotor (1), in particular the rotor (1) according to one of the preceding claims 1 to 13, comprising the steps: 1) Inserting tube blanks (35) into longitudinal grooves (9) of a rotor body (4) equipped with a rotor winding (10), so that the tube blanks (35) are received within the longitudinal grooves (9) between adjacent longitudinal winding sections (12) of the rotor winding (10) in a circumferential direction (8) about a rotational center axis (3) of the rotor body (4), 2) internal high-pressure forming of the tube blanks (35) in such a way that the tube blanks (35) form cooling tubes (15) which are arranged at least in sections in a contour-following manner on longitudinal winding sections (12) adjacent in the circumferential direction (8) in a force-fitting and/or form-fitting connection (16) on the longitudinal winding sections (12). 15. Electrical machine (2), in particular a traction drive for an electric vehicle, comprising a stator and a rotor (1) designed according to one of the preceding claims 1 to 13 or a rotor (1) manufactured according to the preceding method claim 14. *****