Weight-optimized star disk for a rotor of a separately excited electric machine

Abstract

The present invention relates to a star disk (1) for a rotor of a separately excited motor, the star disk being arranged on the end face of the rotor core of the rotor and for carrying the winding head of the rotor, the star disk having a base (3) having a star disk yoke (5) for being arranged on the rotor yoke of the rotor core, a star disk arm (7) extending radially from the star disk yoke (5) for being arranged on the rotor teeth of the rotor core, and a star disk top cover (8) protruding tangentially and axially from the star disk arm (7) for being arranged on the pole shoes of the rotor core, the bottom surface (2) of the base (3) that can be abutted against the end face of the rotor core having a weight-reducing recess (10a, 10b, 10c) for forming an air-filled cavity when the star disk (1) is arranged on the rotor core.

Description

Technical Field

[0001] This invention relates to a star disk for a rotor of a separately excited motor, the star disk being arranged on the end face of the rotor core and for carrying the rotor winding head. The star disk has a base having a star disk yoke for arrangement on a rotor yoke of the rotor core, star disk arms extending radially from the star disk yoke for arrangement on rotor teeth of the rotor core, and a star disk top cover projecting tangentially and axially from the star disk arms for arrangement on pole shoes of the rotor core. The invention also relates to a rotor and a separately excited motor. Background Technology

[0002] This article focuses on separately excited or electrically excited motors used in electrified motor vehicles, such as electric or hybrid vehicles. Such separately excited motors have a fixed stator with energized stator windings and a rotor with energized rotor windings rotatably supported relative to the stator. The rotor has a rotor core, such as a lamination assembly, which carries the rotor windings. The winding conductors of the rotor windings can be constructed, for example, as wires wound around the salient poles of the rotor core, which is manufactured in a salient-pole configuration. The rotor windings form winding heads on opposite end faces of the rotor core.

[0003] To mechanically support the rotor winding heads against high centrifugal forces during rotor rotation, star disks and support rings are known in the prior art, such as DE 10 2018 128 521 A1. The star disks are arranged on the axially opposite end faces of the lamination assembly, such that the star disks are also wound with wire and positioned between the end faces and the winding heads after winding. Each star disk is surrounded by a support ring, such that the star disks and support rings jointly bear the mechanical load caused by centrifugal forces. The star disks can, for example, have a steel substrate partially encapsulated in plastic injection molding. While this substrate provides high mechanical strength, it also results in undesirable high weight. Summary of the Invention

[0004] The objective of this invention is to provide a mechanically stable and lightweight rotor for a separately excited motor used in motor vehicles.

[0005] According to the present invention, this task is accomplished by a star-shaped disk, a rotor, and a separately excited motor having the features according to the respective independent claims. Advantageous embodiments of the invention are the technical solutions described in the dependent claims, the specification, and the drawings.

[0006] According to the invention, a star-shaped disk for a separately excited motor rotor is arranged on the end face of the rotor core and serves to support the rotor winding head. The star-shaped disk has a base having a star-shaped disk yoke for arrangement on the rotor yoke of the rotor core, star-shaped disk arms extending radially from the star-shaped disk yoke for arrangement on the rotor teeth of the rotor core, and star-shaped disk top covers protruding tangentially and axially from the star-shaped disk arms for arrangement on the pole shoes of the rotor core. The bottom surface of the base, which can abut against the end face of the rotor core, has a weight-reducing recess for forming an air-filled cavity when the star-shaped disk is arranged on the rotor core.

[0007] The present invention also relates to a rotor for a separately excited motor for a motor vehicle. The rotor includes a rotor core having a rotor yoke and salient poles extending radially from the rotor yoke, each salient pole having rotor teeth and pole shoes. Furthermore, the rotor includes two star-shaped disks according to the invention, arranged on axially opposite sides of the rotor core, wherein the cavity is formed between the end face and the recess. The rotor also includes rotor windings, the winding conductors of which are wound around the salient poles and the star-shaped disks, and forming winding heads on the top surfaces of the star-shaped disks. The separately excited motor according to the invention has a fixed-position stator with energized stator windings and a rotor according to the invention rotatably supported relative to the stator. The motor is particularly an electrically excited synchronous motor (SSM), wherein the rotor is particularly configured as an internal rotor.

[0008] The rotor core is constructed, for example, as a lamination assembly of axially stacked electrical steel sheets and manufactured in a salient pole configuration. For this purpose, the rotor core has an annular rotor yoke with an axially through-opening for accommodating the rotor shaft. The rotor shaft, passing through this through-opening, is non-rotatably connected to the rotor core. A plurality of salient poles are distributed circumferentially on the rotor yoke. The rotor teeth or rotor tooth bodies of these salient poles extend radially from the rotor yoke. The rotor teeth may, for example, be configured with parallel sidewalls. Pole shoes are arranged radially outward from the rotor teeth. A groove is formed between two circumferentially adjacent rotor teeth to accommodate an axial winding section of the rotor winding conductor. The pole shoes of two adjacent salient poles close the groove, leaving only a pole gap formed between the pole shoes, which constitutes an inlet opening leading to the corresponding groove for introducing the winding conductor.

[0009] A star-shaped disk, or star-shaped end plate, is arranged on each end face of the rotor core. Each star-shaped disk includes a substrate having a top surface and a bottom surface. The bottom surface abuts against the corresponding end face of the rotor core. The substrate is preferably made of steel. The substrate can be formed, for example, during a forging process. The metal substrate is covered with an electrically insulating layer at least in the areas in contact with the winding conductors, i.e., at least on the top surface and the axially extending side areas. For example, the steel substrate can be partially encapsulated by plastic injection molding.

[0010] The shape of the star-shaped disk corresponds here to the shape of the rotor core predetermined by the salient pole structure. The annular end surface of the rotor yoke is covered by the annular star-shaped disk yoke. The star-shaped disk yoke also has an axial through-section for the rotor shaft. Star-shaped disk arms extend radially from the star-shaped disk yoke, wherein each star-shaped disk arm covers the end surface of one rotor tooth. The star-shaped disk arms can also be constructed with parallel sidewalls. A star-shaped disk top cover is arranged radially outward of the star-shaped disk arm, which axially protrudes from the top surface of the base and tangentially protrudes from the side region, or sidewall, of the star-shaped disk arm. Each star-shaped disk top cover here covers the end surface of one pole shoe.

[0011] In the region of the star-shaped disk arm, the axial extension dimension, or thickness, of the substrate is smaller than the axial extension dimension of the substrate in the regions of the star-shaped disk yoke and the star-shaped disk top cover. Therefore, the star-shaped disk yoke and the star-shaped disk top cover extend radially inward and radially outward from the top surface of the star-shaped disk arm, thus forming a winding cavity together with the star-shaped disk arm to accommodate the winding head. To form the rotor winding, the winding conductors are wound around the rotor teeth and the star-shaped disk arm, such that the axial winding conductor section is arranged in a groove in the sidewall of the rotor teeth, and the end-side winding conductor section forming the winding head is arranged on the top surface of the star-shaped disk arm and held between the star-shaped disk yoke and the star-shaped disk top cover. In particular, the axially protruding star-shaped disk top cover prevents the winding head from slipping due to centrifugal force. The winding conductors are insulated from the steel substrate by an electrical insulation layer that partially covers the substrate. The electrical insulation layer may, for example, have a corrugated structure for guiding the conductors in the transition region between the side and top surfaces of the star-shaped disk arm.

[0012] To reduce the weight of the star disk, the bottom surface of the substrate (on which the substrate rests against the end face of the rotor core) has weight-reducing recesses or indentations. Therefore, the surface of the substrate's bottom surface is not constructed to be flat or planar, but rather has a high profile. Based on these recesses, the bottom surface of the substrate does not rest on the entire surface, but only on the corresponding end face in the area of ​​the resting surface excluding the recesses. When the star disk rests against the rotor core, the end face of the rotor core covers the recesses in the substrate's bottom surface, thus forming air-filled cavities or voids. For example, the recesses can be introduced during the forging process of the steel substrate. Alternatively, the recesses can be introduced after forging the substrate by machining the bottom surface. The recesses are particularly rotationally symmetrical, thus preventing the introduction of imbalances.

[0013] The recesses not only advantageously reduce the weight of the star disk itself, but also prevent the potting compound used to encapsulate the rotor and support the rotor windings from entering the air gap formed by the recesses between the corresponding substrate and the end faces of the rotor core, thus preventing an increase in rotor weight. Furthermore, the load on the star disk with recesses at critical locations is not significantly higher than that of the star disk without recesses. The deformation of the windings, especially the connecting wires, is not significantly increased. In addition, no permanent deformation occurs on the outer side of the rotor.

[0014] Particularly preferably, the abutment region of the substrate surrounds the recess and extends at least along the contour of the substrate. The contour of the substrate is formed, in particular, by the edges of the substrate on its outer and inner peripheries. The outer periphery edge is formed by the outer edges of the star-shaped disk yoke, the star-shaped disk arms, and the star-shaped disk top cover. The inner periphery edge is formed by the circular inner edge of the star-shaped disk yoke, which surrounds the axial through-hole for the rotor shaft and is pressed against the rotor shaft. In the abutment region of the substrate, the surface of the bottom surface bulges relative to the surface in the region of the recess. The recess is thus surrounded by the abutment region, such that, when the star-shaped disk abuts against the rotor core, the abutment region forms a barrier for the potting compound.

[0015] It can be specified that a first recess is formed in the yoke of the star disk, aligned with the arms of the star disk, and / or a second recess is formed in the arms of the star disk, and / or a third recess is formed in the top cover of the star disk. A first connecting rib for stabilization is constructed between the first and second recesses, and / or a second connecting rib for stabilization is constructed between the second and third recesses. By means of the connecting ribs constructed in the star disk for mechanical stability, compared to a star disk made of solid material, similar star disk strength and similar deformation of the winding heads, especially the connecting wires, under centrifugal force are achieved.

[0016] The first recess constructed in the star-shaped disk yoke is radially defined by the inner periphery of the star-shaped disk yoke and a first connecting rib at the transition between the star-shaped disk yoke and the star-shaped disk arm. Circumferentially, abutment sections can be arranged between the first recesses and extend radially from the outer edge of the star-shaped disk yoke toward the inner edge. These abutment sections can extend over the entire radial diameter of the star-shaped disk yoke and circumferentially separate the first recesses from each other, or extend only over a region of the radial diameter of the star-shaped disk yoke, such that the first recesses are circumferentially connected. A threaded hole can be constructed in each abutment section between the first recesses to accommodate a screw for securing the rotor's cap-shaped support ring to the star-shaped disk. This support ring has a hollow cylindrical flange region and a ring-shaped cover region, the flange region abutting the outer surface of the star-shaped disk top cover and thus radially surrounding the star-shaped disk, the cover region being arranged overlapping the top surface of the star-shaped disk. Holes may also be constructed in the cover area, which are arranged in alignment with threaded holes and through which the support ring can be fixed to the star-shaped disk by means of screws.

[0017] The second recess may be constructed in the star-shaped disk arm and defined circumferentially by an abutment area at the lateral outer edge of the star-shaped disk arm and radially by the first and second connecting ribs or by the star-shaped disk yoke and the star-shaped disk top cover. The third recess may be constructed in the star-shaped disk top cover and defined radially by the second connecting rib and the edge of the star-shaped disk top cover.

[0018] In an extended embodiment of the invention, the surface of the connecting rib is retracted relative to the surface of the contact area. In other words, the surface of the connecting rib and the surface of the contact area are not at the same axial height, so that when the star disk is arranged on the rotor core, the connecting rib does not contact the end face. Therefore, the stability of the star disk is improved with minimal increase in weight by using the connecting rib.

[0019] In another embodiment of the invention, the base has a locating pin in the region of the two radially opposed second connecting ribs or in each of the two radially opposed star-shaped disk top covers, for placement in a locating opening in the end face of the rotor core. The locating pin is integrally constructed with the corresponding connecting rib or with the bottom surface of the base in the region of the star-shaped disk top cover. To correctly position the star-shaped disk on the end face, the locating pin is inserted into the corresponding locating opening. The rotor core equipped with the correctly positioned star-shaped disk can then be wound with winding conductors.

[0020] The embodiments and advantages described regarding the star-shaped disk according to the invention are correspondingly applicable to the rotor according to the invention and the motor according to the invention.

[0021] Further features of the invention are derived from the claims, drawings, and description of the drawings. The features and combinations thereof mentioned above in the specification, as well as those mentioned below in the description of the drawings and / or shown separately in the drawings, may be used not only in the given combinations, but also in other combinations or individually. Attached Figure Description

[0022] The present invention will now be described in detail with reference to preferred embodiments and the accompanying drawings. The drawings are as follows:

[0023] Figure 1 A perspective view showing a first embodiment of a star-shaped disk for a separately excited motor rotor; and

[0024] Figure 2 A perspective view showing a second embodiment of the star-shaped disk. Detailed Implementation

[0025] In the accompanying drawings, identical and functionally identical elements are given the same reference numerals.

[0026] Figure 1 and Figure 2 A perspective view showing different embodiments of the star disk 1 for a separately excited motor rotor is shown. The motor can be used, for example, as a drive machine for electrified motor vehicles. The star disk 1 can be attached to the rotor core of the rotor, such as the end face of the lamination assembly, with its bottom surface 2, and there hold the winding head of the rotor windings. The task of the star disk 1 is, in particular, to withstand the high centrifugal force acting on the winding head when the motor rotates at high speed, together with a support ring (not shown) surrounding the star disk 1. The star disk 1 has a metal substrate 3, which is made, in particular, of steel and partially covered with an electrically insulating layer 4, such as plastic.

[0027] The star disk 1 includes: a star disk yoke 5 having a through opening 6 for the rotor shaft; star disk arms 7 extending radially from the star disk yoke 5 with parallel sidewalls; and a star disk top cover 8 disposed radially outside the star disk arms 7. The star disk arms 7 carry the winding heads. The star disk top cover 8 and the star disk yoke 5 protrude axially from the top surface of the star disk arms 7, such that the winding heads disposed on the star disk arms 7 are radially surrounded by the star disk yoke 5 and the star disk top cover 8. To electrically insulate the conductive winding conductors of the rotor windings (which are made of, for example, copper) from the metal substrate 3, all sides of the substrate 3, except for the bottom surface 2 and the outer surface region 9 of the star disk top cover 8, are covered with an electrically insulating layer 4. A support ring (which is made of, for example, stainless steel and bandage-like around the star disk 1) can be pressed against the uncovered outer surface region 9 of the star disk 1.

[0028] Because the base 3 is made of steel, it possesses high strength, thus reliably withstanding loads caused by centrifugal force and minimizing deformation of the rotor windings, especially the connecting wires. Another advantage of the star disk 1 with the iron-containing steel base 3 is that, compared to an aluminum base, the thermal expansion of the iron-containing laminations, copper wires, and steel base 3 is well-matched. This matching thermal expansion has the advantage of reducing relative deformation between components within the rotor.

[0029] However, a drawback of the steel substrate 3 is its relatively large weight. To reduce this weight, weight optimization is implemented on the star disk 1 in the form of recesses 10a, 10b, 10c, or dimples, in the bottom surface 2 of the substrate 3. These recesses 10a, 10b, 10c are separated from the surrounding environment 11 of the star disk 1 by abutment regions 12 on the bottom surface 2 that are raised relative to the recesses 10a, 10b, 10c. The abutment regions 12 extend at least along the contour 13 of the substrate 3, such that the abutment regions 12 have at least an inner edge 14 and an outer edge 15 that are raised relative to the recesses 10a, 10b, 10c of the substrate 3. The inner side of the star disk yoke 5 also serves to form a press fit between the star disk 1 and the rotor shaft of the rotor through-through portion 6, wherein this press fit ensures axial stability between the star disk 1 and the rotor shaft. The contact area 12 forms a contact surface. When the star-shaped disk 1 is arranged on the rotor core, this contact surface is abutted against the end face of the rotor core and pressed against the rotor core by the winding. In this arrangement and pressing state, the recesses 10a, 10b, and 10c covered by the end face of the rotor core constitute air-filled cavities. These cavities remain free of potting material when the rotor is potted.

[0030] The first region that can be used for weight optimization is the star-shaped disk yoke 5. A first recess 10a can be arranged here. The first recess 10a is distributed circumferentially and arranged in the star-shaped disk yoke 5, aligned with the star-shaped disk arms 7. Radially, the first recess 10a is defined by an inner edge 14 and a corresponding first connecting rib 16 located between the star-shaped disk yoke 5 and the star-shaped disk arms 7. Circumferentially, segments 17 of abutment regions 12 are arranged between the recesses 10a. According to… Figure 2 In one embodiment, these segments 17 extend between the inner edge 14 and the outer edge 15 and separate the first recesses 10a from each other. According to... Figure 1 In this embodiment, these segments 17 extend from the outer edge 15 but are spaced apart from the inner edge 14. Thus, the first recesses 10a are connected circumferentially. Each segment 17 between the first recesses 10a also has a threaded hole 18 for receiving a screw, by means of which the support ring can be secured to the corresponding star-shaped disk 1.

[0031] The second region that can be used for weight optimization is the star-shaped disk arm 7. A second recess 10b is arranged there. In the circumferential direction, the second recess 10b is defined by the sidewall region 19 of the outer edge 15 of the star-shaped disk arm 7. (As per...) Figure 2 As shown in the embodiment, in the radial direction, the second recess 10b is defined by the first connecting rib 16 and by the outer edge 15 in the outer surface region 9 of the star-shaped disk top cover 8. The second recess 10b thus extends into the star-shaped disk top cover 8.

[0032] According to Figure 1 As shown in the embodiment, the second recess 10b is defined by a first connecting rib 16 and a second connecting rib 20 between the second recess 10b and a third recess 10c in the star disk top cover 8. The connecting ribs 16, 20, which contribute to the stability of the star disk 1, also have slight weight optimization in this case, in that the surfaces of these connecting ribs are at least partially stripped of material or retracted relative to the surface of the contact area 18.

[0033] On the radially outer side of the two opposing second recesses 10b, a locating pin 21 is constructed in the bottom surface 2, for example in the two radially opposing second connecting ribs 20. The locating pin 21 is arranged in a locating opening in the end face of the rotor core to position the star-shaped disk 1 on the rotor core.

Claims

1. A star disk (1) for a rotor of a separately excited motor, the star disk being disposed on the end face of the rotor core of the rotor and for carrying the winding head of the rotor, the star disk having a base (3), the base having a star disk yoke (5) for being disposed on a rotor yoke of the rotor core, a star disk arm (7) extending radially from the star disk yoke (5) for being disposed on the rotor teeth of the rotor core, and a star disk top cover (8) protruding tangentially and axially from the star disk arm (7) for being disposed on the pole shoes of the rotor core, characterized in that, The bottom surface (2) of the substrate (3) that can abut against the end face of the rotor core has a weight-reducing recess (10a, 10b, 10c) for forming an air-filled cavity when the star disk (1) is arranged on the rotor core.

2. The star-shaped disk (1) according to claim 1, characterized in that, The substrate (3) is made of steel and is at least partially covered with an electrical insulating layer (4).

3. The star-shaped disk (1) according to claim 1 or 2, characterized in that, The bottom surface (2) of the substrate (3) has an abutment area (12) for abutting against the end face of the rotor core, the abutment area surrounding the recess (10a, 10b, 10c) and extending at least along the contour (13) of the substrate (3).

4. The star-shaped disk (1) according to any one of the preceding claims, characterized in that, A first recess (10a) is formed in the star-shaped disk yoke (5) aligned with the star-shaped disk arm (7), and / or a second recess (10b) is formed in the star-shaped disk arm (7), and / or a third recess (10c) is formed in the star-shaped disk top cover (8), wherein a first connecting rib (16) for stabilizing function is constructed between the first recess (10a) and the second recess (10b) and / or a second connecting rib (20) for stabilizing function is constructed between the second recess (10b) and the third recess (10c).

5. The star-shaped disk (1) according to claim 4, characterized in that, The surfaces of the connecting ribs (16, 20) retract relative to the surface of the contact area (12).

6. The star-shaped disk (1) according to claim 4 or 5, characterized in that, The base (3) has a locating pin (21) in the region of the two radially opposite second connecting ribs (20) or in the region of the two radially opposite star-shaped disk top covers (8) for locating openings in the end face of the rotor core.

7. The star-shaped disk (1) according to any one of claims 4 to 6, characterized in that, The abutment region is arranged at least in sections between the first recesses and extends radially from the outer edge of the star-shaped disk yoke toward the inner edge, wherein a threaded hole is provided in each section of the abutment region between the first recesses for receiving a screw to fix the cap-shaped support ring of the rotor onto the star-shaped disk.

8. A rotor for a separately excited motor used in motor vehicles, comprising: - A rotor core having a rotor yoke and salient poles extending radially from the rotor yoke, the salient poles having rotor teeth and pole shoes respectively; - Two star-shaped disks (1) according to any one of the preceding claims, the star-shaped disks being arranged on the axially opposite sides of the rotor core, wherein the air-filled cavity is formed between the end face and the recess (10a, 10b, 10c). - A rotor winding having winding conductors wound around the salient pole and forming a winding head on the top surface of the star disk (1).

9. The rotor according to claim 8, characterized in that, The winding conductor is encapsulated with potting compound, wherein no potting compound is disposed within the cavity.

10. A separately excited motor for motor vehicles, comprising a stator and a rotor according to claim 8 or 9 rotatably supported relative to said stator.

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