Rotor and synchronous machine

Abstract

The invention relates to a rotor (4) for a synchronous machine (1), the rotor having a rotor coil (6) for generating a rotor field, the rotor coil having a plurality of windings (7) for forming electromagnetic poles, wherein the rotor (4) has, for each winding (7), a pole region (8) which supports the winding (7) and which has a pole arm (9) and a pole cap (10). In the pole region (8), the winding (7) is wrapped around the pole arm (9) and is supported on the pole cap (10). On the inside, the pole cap (10) has two support regions (11) which are mutually averted in the circumferential direction (U) and which project beyond the pole arm (9) in the circumferential direction (U) and on which the winding (7) is supported. The pole cap (10) has an outer region (12), which adjoins the support regions (11) on the outside, and two end regions (13), which are mutually averted in the circumferential direction (U) and connect the outer region (12) to the support regions (11). The rotor (4) has a non-laminated rotor core (14) which forms the pole arms (9). The rotor (4) has, for each pole region (8), a laminated cap body (15) which forms the outer region (12) of the associated pole cap (10). The cap bodies (15) are fastened to the rotor core (14) by means of interlocking connections (16). High efficiency can be achieved if the non-laminated rotor core (14) also forms the support regions (11) of the pole caps (10).

Description

[0001] Rotor and synchronous machine

[0002] The present invention relates to a rotor for an electrically separately excited synchronous machine according to the preamble of claim 1. The invention further relates to a synchronous machine equipped with such a rotor.

[0003] A rotor of this type is known, for example, from US 2005 / 0 253 476 A1 and comprises a rotor coil for generating a rotor field, which has several windings for forming electromagnetic poles. The rotor has a pole section for each winding, which supports the respective winding and has a pole arm and a pole cap. In the respective pole section, the winding wraps around the pole arm and is radially supported at the pole cap. The respective pole cap has two support areas radially inside, facing away from each other in the circumferential direction and projecting circumferentially beyond the pole arm, against which the respective winding is radially supported. Furthermore, the respective pole cap has an outer area radially adjoining the support areas and two end areas facing away from each other in the circumferential direction, which connect the outer area to the support areas.The rotor of this type has a non-laminated rotor core that forms the poles, and for each pole region, a laminated cap body that forms the outer surface of the respective pole cap. The cap bodies are attached to the rotor core by means of positive-locking connections. In the known rotor, the pole caps, including the outer surface, the two support areas, and the two end areas, are formed by the respective laminated cap body. The positive-locking connections between the respective cap body and the rotor core are formed by dovetail couplings in the area of ​​the respective pole. At high rotor speeds, the comparatively large mass of the windings leads to a high radial load on the pole caps due to centrifugal force, so the cap bodies must be made of a sufficiently strong material.At the same time, the dovetail couplings must be configured to be sufficiently rigid in order to withstand the high loads.

[0004] In the area of ​​the terminal caps, relatively high electromagnetic requirements must be considered for the efficient operation of the synchronous machine, such as high permeability, high saturation density, and low hysteresis and eddy current losses. However, these electromagnetic requirements are not very compatible with mechanical requirements, such as high yield strength, high tensile strength, and high ductility and elongation at break. Laminated terminal cap bodies, which radially support the respective winding according to the known design, must nevertheless meet the aforementioned high mechanical requirements, so compromises regarding the electromagnetic requirements must be made when selecting the material.

[0005] Other rotors in which the cap bodies, separate from the rotor core, radially support the respective winding are known from JP 2000-166139 A, GB 204433 A, DE 19 18 109 A1, US 10 554 088 B2 and DE 10 2019 219 181 A1. A conventional rotor is known from EP 1 276 205 B1 in which a laminated rotor core forms the rotor arms and the entire polar caps.

[0006] The present invention addresses the problem of providing an improved or at least a different embodiment for a rotor of the type described above or for a synchronous machine equipped therewith, which is characterized in particular by high efficiency at low manufacturing costs.

[0007] This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0008] The invention is based on the general concept of forming the support areas of the polar caps directly on the non-laminated rotor core. This means that these support areas are necessarily not components of the cap bodies and consist of the same material as the rotor core, thus easily achieving the required strength. This offers the advantage that the cap bodies are relieved of the radial load from the windings and ultimately only have to support themselves. Consequently, the mechanical requirements for the cap bodies are significantly reduced. This allows the cap bodies to be manufactured with materials that meet high electromagnetic requirements, thereby improving the efficiency of the synchronous machine equipped with this rotor. At the same time, this efficiency improvement can be achieved relatively inexpensively, since only a comparatively small amount of material is required for the cap bodies.

[0009] According to the invention, the non-laminated rotor core also forms the support areas of the polar caps. The non-laminated rotor core is solid and consists of a single component that forms or comprises a core area, the polars projecting from the core area, and the support areas of the polar caps.

[0010] According to an advantageous embodiment, the positive-locking connections for attaching the respective cap body to the rotor core can be located in the end regions of the respective pole cap. Relocating the positive-locking connections to the end regions simplifies their manufacture. Since the cap bodies are relieved of the centrifugal forces of the windings, the positive-locking connections only need to transmit comparatively little force to securely hold the respective cap body to the rotor core. This allows the positive-locking connections to be configured smaller and more simply than, for example, the comparatively robust dovetail couplings that are used in known rotors between the respective pole and the respective cap body.

[0011] In the present context, a “configuration” corresponds to a “design” and / or a “setup”, so that the phrase “configured so that” is synonymous with the phrase “designed so that” and / or “set up so that”.

[0012] According to an advantageous embodiment, the non-laminated rotor core can also form the end regions of the polar caps. This further simplifies the rotor's construction, thus reducing manufacturing costs.

[0013] The polar ice caps and polar ice caps extend continuously and without interruption along the entire axial length of the rotor core. This measure also leads to a cost-effective rotor design.

[0014] The laminated cap bodies each consist of several sheet metal parts stacked axially. The laminated design prevents eddy currents within the cap bodies. Outside the polar caps, only comparatively few eddy currents are generated, allowing the rotor core, including the polars and support areas, to be configured as solid or non-laminated.

[0015] In an advantageous embodiment, the laminated cap bodies can each have an inner surface radially adjacent to the respective support areas and the respective pole, an outer surface facing radially away from the inner surface, and two circumferential ends facing away from each other in the circumferential direction, which connect the inner surface to the outer surface. A radially external outer contour of the respective pole region can then be formed by the outer surface of the respective cap body and by the end regions. Thus, the cap bodies form a significant portion of the rotor's outer contour. This is advantageous for efficient electromagnetic action, particularly for generating the rotor field.

[0016] In another embodiment, the end regions in the respective pole area can be designed to engage the circumferential ends of the cap body. This creates a simple, positive fit between the end regions and the respective cap body.

[0017] It may be advantageous to design the support areas and end areas on the rotor core in each pole region to form a cap body receptacle. The cap body is inserted axially into this receptacle, which has a radially outer receiving opening that is smaller in the circumferential direction than the cap body. This design secures the cap body radially within the receptacle by positive locking. However, it also prevents the cap body from being inserted radially into the receiving opening. For simplified assembly, the receptacle is configured to allow axial insertion of the cap body. For example, the receptacle can have a constant cross-section in the axial direction. Similarly, the cap body itself can have a constant cross-section in the axial direction.

[0018] In another embodiment, the end regions in each pole area can be plastically deformed such that they encompass the circumferential ends of the cap body. In this embodiment, it is particularly possible to radially position the cap bodies on the polar arm in each pole area, so that the cap body is positioned circumferentially between the two end regions before the end regions are plastically deformed. After the cap bodies are positioned, the end regions are plastically deformed so that they encompass the circumferential ends of the cap body. The cap body is then held in place on the respective polar arm.

[0019] In another embodiment, the cap body can additionally be bonded to the rotor core in the respective pole area. This results in improved adhesion between the rotor core and the cap bodies.

[0020] In the other advantageous embodiment, the end regions can project circumferentially beyond the respective winding in the respective pole area.

[0021] Additionally, it can optionally be provided that in the respective pole area, the respective winding projects circumferentially beyond the ends of the cap body or terminates at the ends of the cap body. This clearly places the end regions outside the support area occupied by the respective winding. Consequently, the end regions do not have to absorb radial forces from the windings, but can instead fulfill a holding function to secure the respective cap body to the rotor core.

[0022] In another advantageous embodiment, the laminated cap bodies may be made of a cobalt-iron alloy. This gives the cap bodies a particularly high saturation magnetization, which is especially higher than that of conventional silicon-iron alloys typically used for electrical steel sheets or yoke plates.

[0023] In an advantageous embodiment, the non-laminated rotor core can be made of a high-strength steel characterized by a yield strength of at least 500 MPa, where MPa stands for megapascal. In particular, the high-strength steel can have a yield strength of at least 600 MPa and preferably at least 700 MPa. For example, a steel of type S700MC can be used. Such a high-strength steel meets particularly high mechanical requirements.

[0024] In another embodiment, the polars can be dimensioned larger in the radial direction than in the circumferential direction. In this design, the respective winding also extends further radially. Consequently, the support areas in the circumferential direction need only project comparatively little beyond the polar to radially support the winding, which has a relatively small surface area on the respective polar. This reduces the stress on the support areas, which facilitates their integration into the rotor core.

[0025] In an advantageous embodiment, the rotor can have a rotor shaft that is rotationally fixed to the rotor core. For this purpose, the rotor core can have a through-hole through which the rotor shaft extends axially. The rotationally fixed connection between the rotor core and rotor shaft can be achieved by frictional engagement. For example, the rotor core can be shrunk onto the rotor shaft. Additionally or alternatively, the rotationally fixed connection between the rotor shaft and rotor core can be created by positive engagement. For example, longitudinal ribs can be formed on the outer circumference of the rotor shaft that engage in complementary longitudinal grooves formed in the through-hole on an inner surface of the rotor core. The rotor can be manufactured relatively inexpensively and with comparatively low imbalance if the rotor shaft and rotor core are manufactured separately.

[0026] An externally excited electric synchronous machine according to the invention, which may in particular be an electric motor and preferably a traction motor of a battery-electric motor vehicle, comprises a stator having a stator coil for generating an electromagnetic stator field, and a rotor of the type described above, which is rotatable relative to the stator about an axis of rotation.

[0027] Further important features and advantages of the invention will become apparent from the dependent claims, the drawing and the associated description of the figures based on the drawing.

[0028] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. Components of a higher-level unit, such as a device, apparatus, or arrangement, mentioned above and those to be mentioned below, which are designated separately, can form separate parts or components of this unit or be integral areas or sections of this unit, even if this is depicted differently in the drawing.

[0029] Preferred embodiments of the invention are shown in the drawing and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0030] Figure 1, the only one, shows a cross-section of a rotor in the area of ​​a pole region.

[0031] As shown in Figure 1, a separately excited electric synchronous machine 1 comprises a stator 2, depicted here only in a rudimentary way, which has a stator coil 3 for generating an electromagnetic stator field. The synchronous machine 1 also has a rotor 4, which is rotatable relative to the stator 2 about an axis of rotation 5. The axis of rotation 5 defines an axial direction A, which runs parallel to the axis of rotation 5, a radial direction R, which runs perpendicular to the axis of rotation 5, and a circumferential direction U, which rotates around the axis of rotation 5. In Figure 1, the axial direction A is perpendicular to the plane of the drawing. The synchronous machine 1 is configured, in particular, as an electric motor. Preferably, the synchronous machine 1 can be a traction motor of a battery-electric vehicle.

[0032] The rotor 4 has a rotor coil 6 for generating a rotor field, which has several windings 7 for forming electromagnetic poles. Only one such winding 7 is shown in Figure 1. The rotor 4 has a pole section 8 for each winding 7, which carries the respective winding 7 and has a pole 9 and a pole cap 10. In Figure 1, the rotor 4 is shown only in the area of ​​one such pole section 8. By way of example and without limiting generality, the rotor 4 could, for instance, be equipped with eight pole sections 8. It is clear that a different number of pole sections 8 is also possible.

[0033] In each pole region 8, the winding 7 encircles the pole 9 and is radially supported at the pole cap 10. Each pole cap 10 has two support areas 11 radially inward, facing away from each other in the circumferential direction U and projecting beyond the pole 9 in the circumferential direction U, against which the winding 7 is radially supported. Furthermore, each pole cap 10 has an outer area 12 radially adjoining the support areas 11, as well as two end areas 13 facing away from each other in the circumferential direction U. The end areas 13 connect the outer area 12 to the support areas 11.

[0034] The rotor 4 also has a non-laminated rotor core 14, which forms the pole arms 9 and the support areas 11 of the respective pole cap 10. The rotor core 14 has a central core area 28 that encloses the axis of rotation and from which the pole arms 9 extend radially. Furthermore, the rotor 4 has a laminated cap body 15 for each pole area 8, which forms the outer surface 12 of the respective pole cap 10. The respective cap body 15 is attached to the rotor core 14 by means of positive-locking connections 16. In the example shown, these positive-locking connections 16 are formed in the end regions 13. Advantageously, the rotor core 14 also forms the end regions 13. Thus, the non-laminated rotor core for all pole areas 8 includes the rotor arms 9, the support regions 11, and the end regions 13 in a single component.In contrast, for each pole area 8, the laminated cap bodies 15 each form a separate component with respect to the rotor core 14, which is attached to the rotor core 14 and fastened to it by means of the positive locking connections 16.

[0035] Each cap body 15 has an inner surface 17 adjacent to the support areas 11 and the polar element 9, an outer surface 18 facing radially away from the inner surface 17, and two circumferential ends 19 facing away from each other in the circumferential direction U. The circumferential ends 19 connect the inner surface 17 with the outer surface 18. Each laminated cap body 15 is formed by means of several sheet metal bodies 20 stacked in the axial direction A. Only one of these sheet metal bodies 20 is visible in Figure 1. Transversely to the axial direction A, the cap body 15 is solid, so that the cross-sectional profile of the cap body 15 or of the respective sheet metal body 20 extending transversely to the axial direction A is closed.

[0036] The pole region 8 has a radially outer contour 21, which is formed by the outer surface 18 of the respective cap body 15 and by the end regions 13. Accordingly, the respective outer contour 21 is formed partly by the cap bodies 15 and partly by the rotor core 14. The proportion of the cap bodies 15 in the outer contour 21 is significantly larger, in particular at least five times larger, than the proportion of the rotor core 14.

[0037] In the embodiment shown here, the end regions 13 encompass the circumferential ends 19, thereby creating the respective positive-locking connection 16. For mounting the rotor 4, it can be provided that in the respective pole region 8, the support regions 11 and the end regions 13 on the rotor core 14 form a cap body receptacle 22 into which the respective cap body 15 is inserted. The cap body receptacle 22 has a receiving opening 23 radially outward, which is dimensioned smaller in the circumferential direction U than the cap body 15. In this case, the cap body 15 can be inserted axially into the cap body receptacle 22. Alternatively, it can also be provided that in the respective pole region 8, the end regions 13 are plastically deformed in order to encompass the circumferential ends 19 of the respective cap body 15.For the assembly of the cap body 15, it can be provided that the end regions 13, in an undeformed state, enlarge the aforementioned receiving opening 23 in the circumferential direction U sufficiently to allow the cap body 15 to be inserted radially into the cap body receptacle 22. With the cap body 15 inserted into the cap body receptacle 22, the end regions 13 can then be plastically deformed such that they subsequently engage the circumferential ends 19 of the cap body 15. This plastic deformation of the end regions 13 reduces the receiving opening 23 in the circumferential direction U. Simultaneously, the respective positive locking connection 16 is created.

[0038] For optimized positioning of the respective cap body 15 on the rotor core

[0039] 14 can also include an adhesive bond 24 which secures the cap body

[0040] 15 is bonded to the rotor core 14, in particular within the cap body receptacle 22.

[0041] In the example shown here, the end sections 13 project in the respective pole region 8 in the circumferential direction U beyond the respective winding 7. In the example shown here, it is also provided that in the respective pole region 8 the respective winding 7 projects in the circumferential direction U beyond the circumferential ends 19 of the cap body 15 or terminates with the circumferential ends 19.

[0042] Advantageously, the laminated cap bodies 15 or the sheet metal bodies 20 can be made of a cobalt-iron alloy. Advantageously, the rotor core 14 can be made of a high-strength steel having a yield strength of at least 500 MPa, in particular at least 600 MPa, and preferably at least 700 MPa.

[0043] In the embodiment shown here, the polars 9 are also dimensioned larger in the radial direction R than in the circumferential direction U, which allows the winding 7 to be configured relatively flat in the circumferential direction U. At the same time, this makes the respective winding 7 comparatively large or elongated in the radial direction R. In the example shown here, the rotor 4 also has a rotor shaft 25 which is rotatably connected to the rotor core 14. The rotor core 14 has a through-hole 26 in the central region 28, through which the rotor shaft 25 extends axially. In the example of Figure 1, the rotor shaft 25 is configured as a hollow shaft, so that the rotor shaft 25 also has a through-hole 27. A coolant, for example, can be passed through this through-hole 27 of the rotor shaft 25.

[0044] *****

Claims

Claims 1. Rotor (4) for an electrically separately excited synchronous machine (1 ), - with a rotor coil (6) for generating a rotor field, which has several windings (7) for forming electromagnetic poles, - wherein the rotor (4) has a pole area (8) for each winding (7) which carries the respective winding (7) and which has a pole (9) and a pole cap (10), - wherein in the respective pole area (8) the winding (7) wraps around the pole (9) and is radially supported on the pole cap (10), - wherein the respective pole cap (10) has two support areas (11) radially inside, facing away from each other in the circumferential direction (U) and projecting in the circumferential direction (U) beyond the pole (9), on which the respective winding (7) is radially supported, - wherein the respective pole cap (10) has an outer area (12) radially adjoining the support areas (11) and two end areas (13) facing away from each other in the circumferential direction (U), which connect the outer area (12) with the support areas (11), - wherein the rotor (4) has a non-laminated rotor core (14) forming the polars (9), - wherein the rotor (4) has a laminated cap body (15) for each pole area (8) which forms the outer surface (12) of the respective pole cap (10), - wherein the cap bodies (15) are attached to the rotor core (14) by means of positive locking connections (16), characterized in that - that the non-laminated rotor core (14) also forms the support areas (11) of the polar caps (10).

2. Rotor (4) according to claim 1, characterized in that, - that the positive locking connections (16) for attaching the respective cap body (15) to the rotor core (14) are formed in the end regions (13) of the respective pole cap (10).

3. Rotor (4) according to claim 1 or 2, characterized in that, - that the non-laminated rotor core (14) also forms the end regions (13) of the polar caps (10).

4. Rotor (4) according to one of the preceding claims, characterized in that - that the laminated cap bodies (15) each have an inner surface (17) radially adjacent to the respective support areas (11) and to the respective polar (9), an outer surface (18) radially away from the inner surface (17) and two circumferential ends (19) facing away from each other in the circumferential direction (U), which connect the inner surface (17) with the outer surface (18), - that a radially outer outer contour (21 ) of the respective pole area (8) is formed by the outer surface (18) of the respective cap body (15) and by the end areas (13).

5. Rotor (4) according to claims 3 and 4, characterized in that, - that in the respective pole area (8) the end areas (13) encompass the circumferential ends (19) of the cap body (15).

6. Rotor (4) according to claim 5, characterized in that, - that in the respective pole area (8) the support areas (11 ) and the end areas (13) form a cap body receptacle (22) on the rotor core (14) into which the respective cap body (15) is inserted and which has a receiving opening (23) radially outside, which is smaller in the circumferential direction (U) than the cap body (15).

7. Rotor (4) according to claim 5 or 6, characterized in that, - that in the respective pole region (8) the end regions (13) are plastically deformed in such a way that they encompass the circumferential ends (19) of the cap body (15).

8. Rotor (4) according to one of claims 4 to 7, characterized in that, - that in the respective pole area (8) the end areas (13) protrude in circumferential direction (U) over the respective winding (7), - that in the respective pole area (8) the respective winding (7) protrudes in the circumferential direction (U) beyond the circumferential ends (19) of the cap body (15) or terminates with the circumferential ends (19) of the cap body (15).

9. Rotor (4) according to one of the preceding claims, characterized in that - that in the respective pole area (8) the cap body (15) is connected to the rotor core (14) is glued.

10. Rotor (4) according to one of the preceding claims, characterized in that - that the laminated cap bodies (15) are made of a cobalt-iron alloy.

11. Rotor (4) according to one of the preceding claims, characterized in that - that the non-laminated rotor core (14) is made of a high-strength steel having a yield strength of at least 500 MPa, in particular at least 600 MPa, preferably at least 700 MPa.

12. Rotor (4) according to one of the preceding claims, characterized in that - that the polars (9) are larger in the radial direction (R) than in the circumferential direction (U).

13. Rotor (4) according to one of the preceding claims, characterized in that - that the rotor (4) has a rotor shaft (25) which is non-rotatably connected to the rotor core (14), - that the rotor core (14) has a through-opening (26) through which the rotor shaft (25) extends axially.

14. Externally excited electric synchronous machine (1), in particular electric motor, preferably traction motor of a battery-electric motor vehicle, - with a stator (2) which has a stator coil (3) for generating an electromagnetic stator field, - with a rotor (3) according to one of the preceding claims, which is rotatable relative to the stator (2) about an axis of rotation (5). *****

Images