Rotor Shaft Arrangement and Method for Manufacturing the Same

Abstract

The present invention relates to a rotor shaft arrangement (1) for a rotor (R) of an electric motor, having a hollow shaft (2) for accommodating a rotor body (K), and a cooling body (3) which is arranged in the hollow shaft (2) and is in thermal contact radially with the hollow shaft (2) and has an axially continuously open structure (S), and therefore a cooling medium in the hollow shaft (2) can flow axially through the cooling body (3). Furthermore, the present invention relates to a rotor (R) with the rotor shaft arrangement (1) according to the invention and also to an electric motor with corresponding rotor (R). The invention also relates to a method for producing the rotor shaft arrangement (1).

Claims

1. Rotor shaft arrangement (1) for a rotor (R) of an electric motor, having: a hollow shaft (2) for accommodating a rotor body (K), and a cooling body (3) which is arranged in the hollow shaft (2) and is in thermal contact radially with the hollow shaft (2) and has an axially continuously open structure (S), and therefore a cooling medium in the hollow shaft (2) can flow axially through the cooling body (3).

2. Rotor shaft arrangement (1) according to claim 1, wherein the cooling body (3) and the hollow shaft (2) are connected to each other with a force fit, and, preferably, the cooling body (3) is pressed into the hollow shaft (2) such that the cooling body (3) can be supported radially on the inner wall (22) of the hollow shaft (2).

3. Rotor shaft arrangement (1) according to claim 1, wherein the open structure (S) is formed by defined channels, such as passage openings, or a meshwork structure.

4. Rotor shaft arrangement (1) according to claim 1, wherein the hollow shaft (2) has, at least in/on its inner wall (22) facing the cooling body (3), structural elements (220), in particular grooves or fins, which are in contact with corresponding radially outer regions (32), in particular structural elements (320), of the cooling body (3), and, preferably, are connected to said regions with a form fit.

5. Rotor shaft arrangement (1) according to claim 1, wherein the cooling body (3) is designed in order to convey the cooling medium axially through its continuously open structure (S) during rotation of the hollow shaft (2).

6. Rotor shaft arrangement (1) according to claim 1, wherein the cooling body (3) has radially extending cooling fins (30), wherein the cooling body (3) preferably has at least one cooling fin, furthermore preferably at least three cooling fins (30).

7. Rotor shaft arrangement (1) according to claim 6, wherein the cooling fins (30) have, at their radial end (32) facing the hollow shaft (2), a widened contact region (320) for thermal contact with the hollow shaft (2), wherein at least some of the widened contact regions (32) are formed integrally with one another, preferably as a peripherally closed ring, and are preferably in flat contact with the hollow shaft (2).

8. Rotor shaft arrangement (1) according to claim 6, wherein the cooling fins (30) extend axially in the hollow shaft (2), in particular rectilinearly along the longitudinal axis (L) or helically about the longitudinal axis (L) of the hollow shaft (2), wherein the cooling body (3) is preferably in the shape of a star or helix.

9. Rotor shaft arrangement (1) according to claim 1, wherein the cooling body (3) has an axially extending heat-conducting element (31) from which the cooling fins (30) preferably extend radially outwards, wherein the heat-conducting element (31) preferably extends along the longitudinal axis (L) of the hollow shaft (2).

10. Rotor shaft arrangement (1) according to claim 9, wherein the heat-conducting element (31) extends axially out of the hollow shaft (2) on one or both sides, and wherein the heat-conducting element (31) preferably has, at its end (310) extending out of the hollow shaft (2), a heat-removing element, in particular with an enlarged surface, such as, for example, a propeller or a disk.

11. Rotor shaft arrangement (1) according to claim 9, wherein the heat-conducting element (31) has an axially extending passage opening which is open axially on both sides for the conduction of a cooling medium.

12. Rotor shaft arrangement (1) according to claim 1, wherein the cooling body (3) is produced from a material having high heat conductivity, such as in particular aluminum or copper.

13. Rotor shaft arrangement (1) according to claim 1, wherein the hollow shaft (2) preferably has, at its axially opposite ends (20, 21), bearing seats (201, 211) which are preferably provided on a region of smaller diameter of the hollow shaft (2) in comparison to the region enclosed axially by said bearing seats, for accommodating the cooling body (3).

14-21. (canceled)

Description

[0034] Further embodiments and advantages of the present invention are described with reference to the following exemplary embodiments on the basis of the figures of the accompanying drawings, in which:

[0035] FIG. 1 shows a perspective sectional view of a rotor with a rotor shaft arrangement according to a first exemplary embodiment of the present invention,

[0036] FIG. 2 shows the rotor according to FIG. 1 without a cooling body,

[0037] FIG. 3 shows a perspective sectional view of a rotor shaft arrangement according to a second exemplary embodiment of the present invention,

[0038] FIG. 4 shows the hollow shaft from FIG. 3, and

[0039] FIG. 5 shows the cooling body from FIG. 3 in a non-sectioned illustration.

[0040] The figures show different exemplary embodiments of a rotor shaft arrangement 1 according to the invention according to the present invention. Identical reference signs denote identical features here.

[0041] The rotor shaft arrangement 1 is, for example, such for a rotor R, as is illustrated in FIG. 1 and can be used, for example, for an electric motor.

[0042] The rotor shaft arrangement 1 firstly has a hollow shaft 2 for the (outer) accommodating of a rotor body K. The rotor body K is preferably placed here onto the hollow shaft 2 in such a manner that they are connected to each other for rotation with each other.

[0043] The hollow shaft 2 is preferably produced from steel, with other materials also being conceivable, however. The hollow shaft 2 can be produced, for example, by a primary forming process, such as, for example, casting, or else a corresponding deformation process, such as, for example forging. Other manufacturing methods are also conceivable.

[0044] At an axial end 20, the hollow shaft 2 preferably has a receiving region 200 for the connection of an output shaft. Said receiving region 200 is designed in FIG. 1 in the form of splines. In the exemplary embodiment illustrated, the hollow shaft 2 also has, at its output end 20, a bearing seat 201 which is provided here by way of example in a region of smaller diameter of the hollow shaft 2.

[0045] In a comparable manner, the hollow shaft 2 can also have at its other, here opposite, axial end 21, a bearing seat 211, preferably in a region of smaller diameter.

[0046] Furthermore, the rotor shaft arrangement 1 has a cooling body 3 arranged in the hollow shaft 2. As can be seen in FIGS. 1 and 3, said cooling body 3 is in thermal contact radially with the hollow shaft 2. Said thermal contact is achieved in particular by direct physical contact between hollow shaft 2 and cooling body 3. The cooling body 3 is preferably connected here to the hollow shaft 2 with a force fit by the cooling body 3 preferably being pressed into the hollow shaft 2. The cooling body 3 can thereby be supported radially on the inner wall 22 of the hollow shaft 2. A radial force acting on the hollow shaft 2—for example from the rotor body K—can thereby be transmitted to the cooling body 3, and therefore the hollow shaft 2 can be formed overall with a smaller wall thickness, which leads in turn to a reduction in the weight of the rotor shaft arrangement 1.

[0047] In particular, the cooling body 3 is intended to be connected to the hollow shaft 2 for rotation therewith, i.e. to be arranged in the latter.

[0048] In order to permit as efficient a removal of heat as possible via the cooling body 3, the cooling body 3 is preferably produced from a material having high heat conductivity. In particular, the cooling body can be produced from aluminum or copper. The cooling body can likewise be produced here by a deformation process and/or primary forming process and/or a machining manufacturing method or else a combination of these or other manufacturing methods (for example generative manufacturing methods). For example, the cooling body 3 can be provided as an aluminum cast part or forged aluminum component.

[0049] In order to permit high removal of heat, the cooling body 3 has an axially continuously open structure S, and therefore a cooling medium in the hollow shaft 2 and preferably flowing through the hollow shaft 2 can flow axially through the cooling body 3. In other words, the cooling body 3 is of continuously open design in order to provide as large a surface as possible for the removal of heat which is conveyed by a cooling medium flowing completely through the cooling body 3. The open structure S of the cooling body 3 makes it possible to achieve a continuous throughflow of a cooling medium, which has the result of efficient cooling of the components. Even though basically any cooling medium, even liquid cooling media, is conceivable, air is preferably used as the cooling medium. Consequently, the mass moving during operation can also be reduced while an easily available cooling medium can be provided in a simple manner at the same time.

[0050] The cooling medium can be conducted through the hollow shaft 2, for example via the end regions 20, 21, which are open axially on both sides, of said hollow shaft. Introduction and/or removal via other regions of the hollow shaft 2 is basically also conceivable. For example, corresponding (radial) channels could thus be introduced into the wall of the hollow shaft 2 in order to allow a certain cooling medium to flow through said hollow shaft and through the cooling body 3.

[0051] The open structure S can be provided by defined channels, such as passage openings, or else a meshwork structure, or a combination of both. In particular, for the efficient removal of heat, it is advantageous if the structure S provides as large a surface as possible past which the cooling medium can flow while the latter flows through the hollow shaft 2 and in particular through the cooling body 3.

[0052] As can be gathered in in particular FIG. 4, the hollow shaft 2 can have structural elements 220 at least in or on its inner wall 22 facing the cooling body 3. As illustrated in FIG. 4, said structural elements 220 can be designed as grooves or else as fins or a combination of the two. Said structural elements 220 are in turn in contact with corresponding radially outer regions 32 of the cooling body 3, as is apparent in FIG. 3 in the lower region of the rotor shaft arrangement 1 which is illustrated. As shown, for example, in FIG. 5, said radially outer regions 32 are likewise designed here as structural elements 320. The corresponding structural elements 220, 320 are preferably designed here in such a manner that they are connected to one another with a form fit when the cooling body 3 is accommodated in, and preferably pressed into, the hollow shaft 2. By this means, a rotationally fixed connection between hollow shaft 2 and cooling body 3 can also be improved.

[0053] As can be gathered from FIGS. 1, 3 and 5, the cooling body 3 can have radially extending cooling fins 30. Cooling fins 30, because of their generally flat configuration, have a large surface which can be used for efficient removal of heat.

[0054] As shown in particular in FIG. 5, the cooling fins 30 can have, at their radial end 32 facing the hollow shaft 2, a widened contact region 320 for thermal contact with the hollow shaft 2. Said contact regions 320 are preferably designed in the form of the aforementioned structural element 320 in order to be able to be connected to correspond corresponding structural elements 220 of the hollow shaft 2 preferably with a form fit. Overall, a widened configuration of the cooling fin ends by means of the widened contact regions 320 results in particularly efficient transport of heat from the hollow shaft 2 to the cooling body 3 where the heat can in turn be efficiently removed because of the open structure S.

[0055] As not illustrated in the figures, the widened contact regions 320 can also be at least partially formed integrally with one another. As large a contact surface as possible between cooling body 3, on the one hand, and hollow shaft 2, on the other hand, can thereby be provided when they are preferably in full contact with each other. Particularly preferably, the widened contact regions 320, if they are all connected to one another, can be designed as a peripherally closed (contact) ring in order to form a maximum flat contact of the cooling body 3 with the hollow shaft 2. The inner side of such a ring structure also forms a further surface toward the open structure S, which in turn efficiently conveys the removal of heat.

[0056] As illustrated in the exemplary embodiments, the cooling fins 30 can extend axially in the hollow shaft 2. Such an axial extent, as illustrated in FIGS. 1, 3 and 5, can be an extent rectilinearly along the longitudinal axis L of the hollow shaft 2. Then, as shown in FIG. 5, the cooling body 3 is in the shape of a star in cross section. The latter is distinguished in particular by a large surface with little use of material and therefore with a low weight.

[0057] However, it is also conceivable for the axial extent of the cooling fins 30 to be formed by a helical extent of the cooling fins 30 around the longitudinal axis L of the hollow shaft 2. A cooling body 3 formed in such manner is then preferably in the shape of a helix which can optionally be surrounded by a peripheral contact ring, as previously described. Such a helix shape has in particular the advantage that, during a rotational movement of the rotor shaft arrangement about the longitudinal axis L or about a rotation axis of the rotor R during operation, said helix shape can be used for the active conveying of the cooling medium, which is required for removing heat, through the hollow shaft 2 and consequently through the cooling body 3.

[0058] In principle, of course, all other embodiments and directions of extent of cooling fins 30 are also conceivable. For example, it is also possible to provide a plurality of axially spaced-apart groups of cooling fins which are each designed by themselves in the manner of propellers and consequently permit a further improvement in the conveying of a cooling medium through the hollow shaft 2 and the cooling body 3.

[0059] The cooling body 3 shown in FIG. 5 has a total of six cooling fins 30, with the invention not being limited thereto. For example, it is also possible for only one cooling fin 30 (for example in a configuration in the shape of a helix) or else for a plurality of cooling fins 30, for example up to 50 cooling fins 30, to be provided. If the cooling fins 30 extend, for example, longitudinally or axially, as illustrated in FIG. 5, the cooling body 3 preferably has at least two and furthermore preferably at least three cooling fins 30. The plurality of cooling fins 30 are then preferably arranged distributed uniformly over the circumference of the cooling body 3 in order to provide a uniform radial support on the inner wall 22 of the hollow shaft 2.

[0060] The cooling body 3 can have an axially extending heat-conducting element 31. The cooling fins 30 can extend radially outwards from said heat-conducting element 31, as illustrated in the figures. The heat-conducting element 31 can preferably extend along the longitudinal axis L of the hollow shaft 2. The heat-conducting element 31 consequently forms a receiving region for cooling elements which are preferably arranged rotationally symmetrically and extend therefrom, such as, for example, the cooling fins 30 illustrated here.

[0061] In a preferred embodiment, the heat-conducting element 31 extends out of the hollow shaft 2 axially on one side (compare FIGS. 1 and 3) or else on both sides (not illustrated). The heat removed via the cooling body 3 can thereby be reliably removed from the rotor shaft arrangement 1. The heat-conducting element 31 can furthermore have a heat-removing element (not illustrated here) at its end 310 extending out of the hollow shaft 2. Said heat-removing element can be designed, for example, as a shaped element. In particular, the heat-removing element is distinguished by an enlarged surface in comparison to the cross section of the heat-conducting element 31. The heat-removing element can be designed, for example, as a disk and particularly preferably as a propeller in order to permit as efficient a removal of heat as possible. The heat-removing element can be provided here within a region with cooling medium. The cooling medium can be a liquid; or preferably also air.

[0062] As not illustrated in the embodiments of the figures, the heat-conducting element 31 can have an axially extending passage opening which is open axially on both sides for the conduction of a cooling medium. The passage opening likewise extends here preferably along the longitudinal axis L of the hollow shaft 2. Said passage opening can serve, for example, for the conduction of a liquid cooling medium. It is also conceivable for said passage opening to serve for the additional enlargement of the surface of the cooling body 3 and therefore for increased removal of heat.

[0063] It has already been mentioned that the hollow shaft 2 preferably has bearing seats 201, 211 at its axially opposite ends 20, 21. Said bearing seats are preferably provided on a region of smaller diameter of the hollow shaft 2; this in particular in comparison to the region enclosed axially by said bearing seats, for accommodating the cooling body 3 in the hollow shaft 2.

[0064] As illustrated in FIG. 1, the rotor shaft arrangement 1 together with a rotor body K accommodated thereon or on the hollow shaft 2 thereof forms a rotor R according to the invention. Said rotor R in turn together with a stator (not shown) surrounding said rotor forms an electric motor according to the invention. The latter can then customarily be correspondingly arranged and designed in order to be correspondingly operated and to remove the generated torque. The torque can be undertaken here, for example, via an output shaft arranged on the output side 200.

[0065] The heat-conducting element 31, which extends axially out of the hollow shaft 2, of a corresponding electric motor can extend, preferably with its heat-removing element, into a cooling medium, such as, for example, air or cooling liquid, in order to provide as efficient a removal of heat for the electric motor as possible. Since in particular very high removal of heat can already be achieved with air as the cooling medium, the present invention provides for removal of heat with maximum efficiency with a simultaneously small moving mass and in particular with a particularly simple structural configuration and installation.

[0066] A method for producing a rotor shaft arrangement 1 for a rotor R of an electric motor is illustrated below.

[0067] In a first step, a hollow shaft 2 is provided for accommodating a rotor body K. Such a rotor body K can be, for example, a laminated rotor core. The hollow shaft 2 can be produced in any manner and is provided in particular from steel. The hollow shaft 2 can be produced, for example, by means of a deformation or primary forming process or else a machining manufacturing method and also by means of a generative manufacturing method. Any combination of these or other manufacturing methods is also conceivable.

[0068] In a second step, a cooling body 3 as also shown by way of example in FIG. 5 is provided. Said cooling body 3 is preferably produced from a highly heat-conducting material, such as, for example, aluminum. Examples of suitable manufacturing methods here are, for example, deformation methods, primary forming methods or else machining or generative manufacturing methods or any combination thereof.

[0069] In a further step, the cooling body 3 is arranged in the hollow shaft 2 via an axially open end 21 of the hollow shaft 2 such that the cooling body 3 is in thermal contact radially with the hollow shaft 2. In particular, for this purpose, the cooling body 3 can be introduced axially into the hollow shaft 2 and can preferably be pressed into the hollow shaft 2. The cooling body 3 can thereby also provide a radial supporting effect for the hollow shaft 2 which consequently can be provided, for example, with a smaller wall thickness. The cooling body 3 here has an axially continuously open structure S in such a manner that a cooling medium in the hollow shaft 2 can flow axially through the cooling body 3. The combination of providing a large surface with a component geometry which is overall simple or is simple to produce ensures simple provision of a highly efficient heat-removing cooling construction of the rotor shaft arrangement 1 according to the invention for a rotor R of an electric motor.

[0070] As already described above, the cooling body 3 is arranged in the hollow shaft 2 via an axially open end 21 thereof. After the corresponding arrangement of the cooling body 3 in the hollow shaft 2, the hollow shaft 2 can be deformed and in particular reduced at least at its axially open end 21 serving for the introduction of the cooling body 3, in order preferably to form a region of reduced diameter. As illustrated in FIGS. 1 to 4, said region can then serve, for example, as a bearing seat 211. Furthermore, the region of reduced diameter can also serve for axially blocking or fixing the cooling body 3 in the hollow shaft 2.

[0071] The rotor shaft arrangement 1 can (additionally) also be provided as an engineered variant. In this case, after the arrangement of the cooling body 3 in the hollow shaft 2, an additional element is provided at the one or both axially open ends 20, 21 of the hollow shaft 2. Said additional element is preferably pressed into the hollow shaft 2 in order to at least partially close the open ends. The corresponding additional element can likewise have, for example, the bearing seats 201, 211 here. Furthermore, the additional element can have the structural elements 200 for removing the torque provided by means of the rotor shaft arrangement 1. Also, one or both of the additional elements can have an opening via which the heat-conducting element 31 can extend axially out of the hollow shaft 2 in order to provide removal of heat to the outside.

[0072] The present invention is not limited to the previous exemplary embodiments as long as it is covered by the subject matter of the claims that follow. In particular, the cooling body 3 can be formed geometrically in any manner if it is thermally coupled to the hollow shaft 2 and is of continuously open design in order to allow a cooling medium to flow through said cooling body so as, in turn, to permit a correspondingly efficient removal of heat. Furthermore, the previously described rotor shaft arrangement 1 can basically be used for any type of shaft which in particular requires removal of heat arising during operation.