Salient-pole rotor, electric machine and manufacturing method

Abstract

The invention relates to a salient-pole rotor (3) for an electrically excited synchronous machine (1), having a plurality of salient poles (11) which are spaced apart from one another in the circumferential direction (U) and carry a rotor winding (12), wherein radially outwardly on the salient-pole rotor (3) a plurality of rotor grooves (15) extending parallel to the longitudinal centre axis (4) of the salient-pole rotor (3) are formed which are each located between two adjacent salient poles (11) in the circumferential direction (U), wherein the respective salient pole (11) has, radially outwardly, a curved leg outer contour (16) the radius of curvature (17) of which, outside a central zenith area (18), is smaller than a circle radius (19) of a cylindrical shell (20) of a virtual, circular-cylindrical cylinder (21) which extends concentrically to the longitudinal centre axis (4) and touches all salient poles (11) at the respective leg outer contour (16) in the zenith area (18), and wherein the rotor grooves (15) are closed radially outwardly in such a manner that a circular-cylindrical outer contour (6) is produced radially outwardly on the salient-pole rotor (3). Simplified manufacturing coupled with low friction in an air gap (5) of the synchronous machine (1) can be achieved in that the rotor grooves (15) are closed radially outwardly in each case with a closing portion (23), which are injection-moulded onto the salient poles (11).

Description

[0001] Salient pole rotor, electrical machine and manufacturing process

[0002] The present invention relates to a salient pole rotor for an electrical machine according to the preamble of claim 1. The invention also relates to an electrical machine equipped with such a salient pole rotor and to an associated method for producing such a salient pole rotor.

[0003] A generic salient-pole rotor is known from DE 10 2020 130 123 A1. Such a salient-pole rotor has a plurality of salient poles, i.e., two or more salient poles spaced apart from one another in the circumferential direction, which support a rotor winding. A plurality of rotor slots, i.e., again two or more, are formed radially outside the salient-pole rotor. These slots run parallel to the longitudinal center axis of the salient-pole rotor and are located circumferentially between two adjacent salient poles. Each salient pole has a curved outer salient contour on its radial outside, the radius of curvature of which, outside a central zenith region of the respective outer salient contour, is smaller than a circular radius of a cylinder shell of a virtual, circular-cylindrical cylinder that extends concentrically to the longitudinal center axis and that touches the respective salient pole at the respective outer salient contour in the zenith region.In order to reduce the friction in an air gap between the salient pole rotor and a stator of the associated synchronous machine, the rotor slots are closed radially on the outside in such a way that a cylindrical outer contour, preferably a circular cylindrical outer contour, is created radially on the outside of the salient pole rotor.

[0004] In the salient-pole rotor known from the aforementioned DE 10 2020 130 123 A1, the radius of curvature of the curved outer limb contour is smaller, even in the central zenith region, than the circular radius of the cylinder that touches the outer limb contours in the zenith region. In the known salient-pole rotor, the rotor slots are closed by a rotor sleeve, which covers at least the distances between the salient poles in the circumferential direction against the air gap. The rotor sleeve can completely surround the salient-pole rotor in the circumferential direction, so that the rotor sleeve closes off the salient-pole rotor towards the air gap along the entire circumference. The rotor sleeve can be composed of several segments, each of which extends only over part of the circumference and together form the entire circumference.

[0005] Precisely manufacturing such a rotor sleeve or the associated segments is very complex due to unavoidable manufacturing tolerances. A segmented rotor sleeve also presents difficulties in securely and permanently securing the segments to the salient poles, particularly in light of the high speeds of a synchronous machine equipped with such a salient-pole rotor.

[0006] WO 03 / 023940 A1 discloses another salient-pole rotor in which a slot-locking wedge is inserted into each rotor slot such that it borders the rotor winding in the respective rotor slot. The slot-locking wedges are configured so that they do not touch the salient poles. The outer contour of the salient-pole rotor features undercut contours in the circumferential direction at the transition between the salient poles and the slot-locking wedges. Furthermore, the slot-locking wedges are each equipped with at least one coolant channel through which a coolant can flow.

[0007] The present invention addresses the problem of providing an improved or at least a different embodiment for a salient pole rotor of the type described above or for a synchronous machine equipped therewith or for an associated manufacturing method, which is characterized in particular by low friction in the air gap between the salient pole rotor and a stator of an associated synchronous machine, wherein comparatively simple manufacture and / or permanent stability are also sought.

[0008] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0009] The invention is based on the general idea of ​​closing each of the rotor slots radially outward with a closure section that is injection-molded onto the salient poles for this purpose. The closure section, made in particular from a plastic, is thus produced directly on the salient poles, with the injection-molded closure section subsequently adhering to the salient poles and thus being permanently fixed there. The closure sections are injection-molded in such a way that the rotor slots are thereby closed radially outward. By closing the rotor slots radially outward, the friction in the air gap between the salient pole rotor and stator is reduced during operation of the associated synchronous machine. The closure sections can compensate for any manufacturing tolerances of the salient poles during injection-molded production.At the same time, the molded-on closure sections adhere sufficiently firmly to the salient poles, ensuring lasting stability even at high speeds. During molding, the closure sections can form-fit into undercut contours, which can occur particularly in the area of ​​the rotor slots on the salient poles. As a result, the molded-on closure sections are also held radially and circumferentially to the salient poles by form-fitting. The molded-on closure sections then form, at least in sections, the cylindrical or circular-cylindrical outer contour. Preferably, the outer contour is configured as a closed, circular-cylindrical configuration. However, it is generally possible to provide interruptions, gaps, or gaps along the circumference of the outer contour, which can be very small.

[0010] According to an advantageous embodiment, the closure sections can be molded onto the salient poles such that a radius of the outer contour corresponds to the circular radius of the virtual cylinder. In other words, by molding the closure sections, the salient pole rotor receives a circular-cylindrical outer contour whose radius is the same as the circular radius of the imaginary or virtual cylinder. As a result, the outer contour of the salient pole rotor also touches the respective salient pole at the respective salient outer contour in the zenith region. Preferably, the outer contour touches the zenith regions of at least two, preferably all, salient poles. In this way, the closure sections extend radially just as far as the zenith regions of the curved salient outer contours. As a result, the annular gap is not impaired in the radial direction by the closure sections, in particular, it is not reduced or narrowed.In this way, it is particularly possible to modify a conventional salient-pole rotor in an existing synchronous machine by molding the closure sections onto it into a salient-pole rotor according to the invention, without having to adapt or otherwise modify the stator of the synchronous machine. By using the salient-pole rotor according to the invention, the annular gap is evened out or homogenized along its inner surface, thereby reducing friction in the air gap during operation.

[0011] According to another advantageous embodiment, the salient poles in the zenith region can have a radius of curvature that corresponds to the radius of the outer contour. The outer contour of the salient pole rotor is then formed by the zenith regions of the salient poles and by the molded-on closure sections, which alternate in the circumferential direction. In other words, the selected geometry of the salient poles in the zenith region ensures that the outer contour of the salient pole rotor forms a circular cylinder that is segmented in the circumferential direction, with the individual segments being formed by the zenith regions of the salient poles and by the closure sections, which alternate in the circumferential direction. The molded-on closure sections are thus separate from one another or separated from one another by the zenith regions of the salient poles.

[0012] In another advantageous embodiment, it can be provided that a slot closure wedge is inserted into each rotor slot, which is adjacent to or in contact with the rotor winding in the respective rotor slot. The closure sections are configured such that they touch the slot closure wedges. In particular, it can be provided that the closure sections are injection-molded onto the slot closure wedges. Injection-molded of the closure sections also onto the slot closure wedges simplifies the manufacture of the salient pole rotor. The slot closure wedges can be configured such that they are radially supported in the respective rotor slot on the two salient poles that are adjacent to the respective rotor slot. As a result, the slot closure wedges are held in a form-fitting manner in the respective rotor slot on the salient pole rotor. The slot closure wedges can be configured such that they tightly close the respective rotor slot.The slot closure wedges can also be fixed to the rotor winding, e.g. by means of adhesive.

[0013] In the present context, a ‘configuration’ corresponds to a ‘design’ and / or a ‘facility’, so that the phrase ‘configured so that’ is synonymous with the phrase ‘designed so that’ and / or ‘arranged so that’.

[0014] According to a particularly advantageous embodiment, the slot-locking wedges can each contain at least one coolant channel through which a coolant can flow. When a salient-pole rotor is installed in the synchronous machine, the coolant channels of the slot-locking wedges can be integrated into a rotor cooling system, such that the coolant flows through the cooling channels during operation of the synchronous machine. The slot-locking wedges thus have an additional function that improves the operation of the synchronous machine.

[0015] According to another advantageous embodiment, the closure sections can be made of an electrically insulating or dielectric material. Additionally or alternatively, the closure sections can be made of a non-magnetic or non-ferromagnetic material or plastic, such as thermosets or thermoplastics. This eliminates any adverse interaction of the molded closure sections with the alternating electromagnetic field acting within the synchronous machine between the salient pole rotor and the stator of the synchronous machine.

[0016] The salient pole rotor can have a rotor body on which the salient poles are formed. For this purpose, the rotor body can have a central core from which the salient poles emanate. The rotor body can in particular form a rotor yoke. The rotor body can be formed by a lamination stack, in particular by a yoke lamination stack. The core and the salient poles are then integrally formed on the laminations of the lamination stack or on the yoke laminations of the yoke lamination stack. For this purpose, the respective salient pole can in particular have a pole shaft connected to the core and a pole shoe connected to the core via the pole shaft. The rotor winding is wound around the pole shafts of the salient poles and is covered radially on the outside by the pole shoes and supported radially on the inside by the core.

[0017] An electrical machine according to the invention, which can be configured in particular as an electrically excited synchronous machine, has a salient pole topology and comprises a stator and a salient pole rotor of the type described above. The salient pole rotor is mounted so as to be rotatable about its longitudinal center axis relative to the stator, forming an air gap. The air gap is located radially outside the salient pole rotor and radially inside the stator and extends in a closed, annular manner in the circumferential direction.

[0018] A method according to the invention for producing such a salient-pole rotor for an electrical machine, preferably for an electrically excited synchronous machine, is based on a salient-pole rotor having a plurality of salient poles spaced apart from one another in the circumferential direction, which support a rotor winding. A plurality of rotor slots extending parallel to the longitudinal center axis of the salient-pole rotor are formed radially on the outside of the salient-pole rotor and located circumferentially between two adjacent salient poles. The respective salient pole has a curved outer salient contour on the radial outside, the radius of curvature of which, outside a central zenith region of the respective outer salient contour, is smaller than a circular radius of a cylinder shell of an imaginary or virtual, circular-cylindrical cylinder that extends concentrically to the longitudinal center axis and that touches all salient poles at the respective outer salient contour in the zenith region.To manufacture the salient pole rotor, closure sections are now injection-molded onto the salient poles in such a way that the rotor slots are closed radially on the outside.

[0019] According to an advantageous embodiment of the manufacturing method, the closure sections can be molded onto the salient poles in such a way that a circular-cylindrical outer contour is created radially on the outside of the salient pole rotor, the radius of which corresponds to the circular radius of the cylinder. In particular, the manufacturing method can be modified so that the embodiments and features mentioned above for the salient pole rotor can be implemented cumulatively or alternatively, as well as in any desired combination. In particular, the method can be configured such that, before the closure sections are molded onto the rotor slot, a slot closure wedge is inserted into each rotor slot, with the closure sections also being molded onto the slot closure wedges.

[0020] Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures based on the drawings.

[0021] It is understood that the features mentioned above and those to be explained below can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. Components mentioned above and those to be mentioned below of a higher-level unit, such as a device, a device, or an arrangement, which are designated separately, may form separate parts or components of this unit or be integral areas or sections of this unit, even if this is shown differently in the drawings.

[0022] Preferred embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components.

[0023] They show, schematically,

[0024] Figure 1 shows a highly simplified cross-section of a synchronous machine with a salient pole rotor before injection molding of closure sections,

[0025] Figure 2 shows a cross section as in Figure 1, but after the closure sections have been injected.

[0026] According to Figures 1 and 2, an electrically excited synchronous machine 1 comprises a stator 2, shown here only as a circle, and a salient-pole rotor 3, which is rotatably mounted about its longitudinal central axis 4 relative to the stator 2, forming an air gap 5. The air gap 5 is shown exaggeratedly large in the radial direction. The air gap 5 is delimited radially inward by an outer contour 6 of the salient-pole rotor 3 and radially outward by an inner contour 7 of the stator 2. Furthermore, the air gap 5 extends in a closed ring in a circumferential direction U. The circumferential direction U of the salient-pole rotor 3 rotates around the longitudinal central axis 4. The circumferential direction U of the synchronous machine 1 rotates around its axis of rotation 8, which usually coincides with the longitudinal central axis 4 of the salient-pole rotor 3. The longitudinal central axis 4 defines a longitudinal direction that extends parallel to the longitudinal central axis 4.The radial direction is perpendicular to the longitudinal direction and can in particular be perpendicular to the longitudinal central axis 4.

[0027] According to Figures 1 and 2, the salient-pole rotor 3 comprises a rotor body 9 having a central core 10 and a plurality of salient poles 11 projecting radially from the core 10, spaced apart from one another in the circumferential direction U, and carrying a rotor winding 12. The salient poles 11 each have a pole shoe 13 connected to the core 10 via a pole shaft 14 concealed by the rotor winding 12. Typically, the rotor body 9 is formed by a stack of laminations in which a plurality of separate laminations are stacked one on top of the other parallel to the longitudinal center axis 4. The core 10 and the salient poles 11 are then formed by corresponding sections of these laminations.

[0028] Radially on the outside of the salient pole rotor 3, several rotor slots 15 are formed, which run parallel to the longitudinal center axis 4 and are located in the circumferential direction U between two adjacent salient poles 11. The rotor slots

[0029] 15 are formed by the spaces not filled by the rotor winding 12, which are present in the circumferential direction U between the adjacent salient poles 11. In the embodiments shown here, the salient pole rotor 3 has a total of six salient poles 11, so that accordingly, exactly six rotor slots 15 are present.

[0030] The respective salient pole 11 has a curved outer leg contour 16 radially outward. These curved outer leg contours 16 have a radius of curvature 17 which varies in the circumferential direction U along the outer leg contour 16. In the examples shown here, the radius of curvature 17 of the outer leg contour 16 varies such that it is

[0031] 16 is smallest and increases towards a central zenith region 18 of the respective outer leg contour 16. In the zenith region 18, the respective outer leg contour 16 accordingly has the largest radius of curvature 17.

[0032] In the salient poles 11 shown here, the outer contours 16 of the legs are shaped or curved such that the radius of curvature 17 outside the respective central zenith region 18 is smaller than a circular radius 19 of a cylinder shell 20 of an imaginary or virtual circular-cylindrical cylinder 21. This virtual cylinder 21 is indicated in Figures 1 and 2 with a broken line and extends concentrically to the longitudinal central axis 4, so that the circle center of the circular radius 19 lies on the longitudinal central axis 4. The imaginary cylinder 21 is dimensioned such that it touches all of the salient poles 11 at the respective outer contour 16 of the legs in the zenith region 18. Because the radii of curvature 17 of the outer leg contours 16 outside the zenith region 18 are smaller than the circle radius 19, the respective outer leg contour 16 moves away from the imaginary cylinder 21 with increasing distance from the zenith region 18.This results in gaps 22 between the shell 20 of the imaginary cylinder 21 in the area of ​​the rotor grooves 15, which also extend along the outer contours 16 of the legs to the respective zenith region 18. These gaps 22 can be seen in Figure 1.

[0033] To eliminate these gaps 22, as shown in Figure 2, the rotor slots 15 are each closed radially outwardly with a closure section 23, wherein the respective closure section 23 is molded onto the salient poles 11. The closure sections 23 are molded onto the salient poles 11 in such a way that a circular-cylindrical shape is created for the outer contour 6 on the radially outward side of the salient pole rotor 3. In other words, the gaps 22 are compensated or filled with the closure sections 23 in order to create a circular-cylindrical outer contour 6 for the salient pole rotor 3.

[0034] A preferred configuration is one in which the closure sections 23 are specifically molded onto the salient poles 11 in such a way that a radius 24 of the outer contour 6 is the same size as the circular radius 19 of the cylinder 21. Consequently, the outer contour 6 of the salient pole rotor 3 is the same size as the cylinder jacket 20 of the imaginary cylinder 21, which touches the salient poles 11 at their outer salient contour 16 in the respective zenith region 18.

[0035] In a preferred embodiment, the salient poles 11 can have a radius of curvature 17 in the zenith region 18 that corresponds to the radius 24 of the outer contour 6 and thus to the circular radius 19 of the cylinder 21. The outer contour 6 of the salient pole rotor 3 is then formed by the zenith regions 18 of the salient poles 11 and by the molded-on closure sections 23, wherein the zenith regions 18 and the closure sections 23 alternate in the circumferential direction U. In the preferred example shown here, a slot closure wedge 25 is inserted into each of the rotor slots 15 such that the respective slot closure wedge 25 in the respective rotor slot 15 borders on the rotor winding 12 and, in particular, touches it. The molded closure sections 23 touch the slot closure wedges 25. In principle, it is conceivable to insert the slot closure wedges 25 axially into the rotor slots 15 after the molding of the closure sections 23.However, an embodiment is preferred in which the slot closure wedges 25 are inserted into the rotor slots 15 before the closure sections 23 are molded on. Subsequently, the closure sections 23 can also be molded onto the slot closure wedges 25. According to a preferred embodiment, the slot closure wedges 25 can contain at least one coolant channel (not shown here), through which a coolant can flow and which can be integrated, in particular, into a rotor cooling system such that a coolant flows through the cooling channels during operation of the synchronous machine 1.

[0036] The closure sections 23 are made of an electrically insulating or dielectric material. Additionally or alternatively, the closure sections are made of a non-magnetic or non-ferromagnetic material. The material of the closure sections 23 is preferably an electrically insulating, non-magnetic plastic.

[0037] *****

Claims

Claims 1. Salient pole rotor (3) for an electrical machine, in particular an electrically excited synchronous machine (1), - with two or more salient poles (11) spaced apart in the circumferential direction (U) which carry a rotor winding (12), - wherein two or more rotor grooves (15) are formed radially outside on the salient pole rotor (3) and extend parallel to the longitudinal central axis (4) of the salient pole rotor (3), which are located in the circumferential direction (U) between two adjacent salient poles (11), - wherein the respective salient pole (11) has a curved outer salient contour (16) radially outward, the radius of curvature (17) of which outside a central zenith region (18) is smaller than a circular radius (19) of a cylinder jacket (20) of a virtual, circular-cylindrical cylinder (21) which extends concentrically to the longitudinal central axis (4) and which touches the respective salient pole (11) at the respective outer salient contour (16) in the zenith region (18), - wherein the rotor slots (15) are closed radially on the outside, such that a cylindrical outer contour (6) is formed radially on the outside of the salient pole rotor (3), characterized in that - that the rotor slots (15) are each closed radially on the outside with a closure section (23), - that the closure sections (23) are injection-molded onto the salient poles (11) and each form the cylindrical outer contour (6) at least in sections.

2. Salient pole rotor (3) according to claim 1, characterized in - that the closure sections (23) are injection-molded onto the salient poles (11) in such a way that a radius (24) of the outer contour (6) corresponds to the circular radius (19) of the virtual cylinder (21).

3. Salient pole rotor (3) according to claim 1 or 2, characterized in - that the salient poles (11) in the zenith region (18) have a radius of curvature (17) which corresponds to the radius (24) of the outer contour (6), - that the outer contour (6) is formed by the zenith regions (18) of the salient poles (11) and the injection-molded closure sections (23), which alternate in the circumferential direction (U).

4. Salient pole rotor (3) according to one of the preceding claims, characterized in - that a slot closure wedge (25) is inserted into each rotor slot (15), which is adjacent to the rotor winding (12) in the respective rotor slot (15), - that the locking sections (23) touch the slot locking wedges (25).

5. Salient pole rotor (3) according to claim 4, characterized in - that the closure sections (23) are injection-molded onto the slot closure wedges (25).

6. Salient pole rotor (3) according to claim 4 or 5, characterized in - that the slot closure wedges (25) each contain at least one coolant channel through which a coolant can flow and are integrated into a rotor cooling system such that a coolant flows through the coolant channels during operation of the synchronous machine (1).

7. Salient pole rotor (3) according to one of claims 4 to 6, characterized in - that the slot closure wedges (25) have the closure sections (23), so that the cylindrical outer contour (6) is produced by inserting the slot closure wedges (25) into the rotor slots (15).

8. Salient pole rotor (3) according to one of the preceding claims, characterized in - that the closure sections (23) consist of an electrically insulating or dielectric material or plastic.

9. Salient pole rotor (3) according to one of the preceding claims, characterized in - that the closure sections (23) consist of a non-magnetic or non-ferromagnetic material or plastic.

10. Electrical machine, in particular electrically excited synchronous machine (1). - with a stator (2), - with a salient pole rotor (3) according to one of the preceding claims, - wherein the salient pole rotor (3) is mounted so as to be rotatable about its longitudinal central axis (4) relative to the stator (2) while forming an air gap (5).

11. Method for producing a salient pole rotor (3) for an electrical machine, in particular an electrically excited synchronous machine (1), - wherein the salient pole rotor (3) has a plurality of salient poles (11) spaced apart from one another in the circumferential direction (U) and carrying a rotor winding (12), - wherein radially outside on the salient pole rotor (3) there are formed a plurality of rotor grooves (15) extending parallel to the longitudinal central axis (4) of the salient pole rotor (3), which are located in the circumferential direction (U) between two adjacent salient poles (11), - wherein the respective salient pole (11) has a curved outer salient contour (16) radially outward, the radius of curvature (17) of which outside a central zenith region (18) is smaller than a circular radius (19) of a cylinder jacket (20) of a virtual, circular-cylindrical cylinder (21) which extends concentrically to the longitudinal central axis (4) and which touches all salient poles (11) at the respective outer salient contour (16) in the zenith region (18), - in which closure sections (23) are injection-molded onto the salient poles (11) in such a way that the rotor slots (15) are thereby closed radially on the outside.

12. Method according to claim 11, characterized in that - that the closure sections (23) are injection-molded onto the salient poles (11) in such a way that a circular-cylindrical outer contour (6) is produced radially on the outside of the salient pole rotor (3), the radius (24) of which corresponds to the circular radius (19) of the cylinder (21).

13. Method according to claim 11 or 12, characterized in that - that before the closure sections (23) are molded on, a slot closure wedge (25) is inserted into each rotor slot (15), - that the closure sections (23) are also injection-molded onto the slot closure wedges (25).

Images