Rotor shaft having integrated contact slip rings for a separately excited electric machine (FSM)

Abstract

The invention relates to a slip ring arrangement (1) for a rotor shaft of an electric machine, comprising: a substantially hollow-cylindrical main body (2); a slip ring (3); a conductor element (4) which is electrically connected to the slip ring (3); a plastics overmolding (5) which runs through the main body (2) at least in some portions and fixes / retains the slip ring (3) in its position and surrounds the conductor element at least in some portions, wherein: the plastics overmolding (5) is connected for conjoint rotation to the main body within the main body (2) by means of a force- and / or form-locking connection; the plastics overmolding (5) forms an undercut (6) in the radial direction with respect to the main body (2) in order to prevent movement of the main body (2), the slip ring (3) and the conductor element (4) relative to one another in the axial direction. The invention further relates to a rotor shaft (9) and to a method for producing a slip ring arrangement (1) for a rotor shaft (9) of an electric machine.

Description

[0001] P240742

[0002] - 1 -

[0003] Rotor shaft with integrated contact slip rings for an externally required electric machine (FSM)

[0004] The invention relates to a slip ring arrangement for a rotor shaft of an electric machine, a rotor shaft of an electric machine comprising a slip ring arrangement, and a method for manufacturing a slip ring arrangement for a rotor shaft of an electric machine.

[0005] Electric motors are increasingly being used for propulsion in motor vehicles to create alternatives to combustion engines that require fossil fuels. Considerable efforts have already been made to improve the everyday usability of electric drives and to offer users the familiar driving comfort.

[0006] In the development of electric motors for electric drives, there is a persistent need to increase their power density and efficiency while simultaneously reducing manufacturing costs, as the vehicle's cost and weight are largely determined by the battery size. In this context, it is also common to design electric motors as separately excited synchronous machines (FSMs). Here, electrical power must be transferred to the rotor of a separately excited synchronous machine to excite the rotor windings. For traction motors, a contact-based transformer is typically used for this purpose. When these windings are energized, a magnetic field is generated, which, in combination with the stator's magnetic field, produces a torque. The strength of the rotor field can be adjusted by varying the current applied. This allows the machine's behavior to be continuously optimized for efficiency in the respective driving situation.

[0007] Slip ring assemblies are known from the still unpublished documents 10 2024 119 749.8, 10 2024 119 750.1, 10 2024 119 752.8. These assemblies are inserted axially into a hollow shaft of an electric machine and are designed in multiple parts. P240742

[0008] - 2 -

[0009] The object of the invention is now to provide an improved slip ring arrangement which has a compact design and thus addresses the high requirements for small space requirements and high power density, particularly in the field of electric vehicle drives.

[0010] This problem is solved by the measures specified in the independent claims. Advantageous embodiments can be found in the dependent claims.

[0011] P240742

[0012] - 3 -

[0013] According to a first aspect, a slip ring arrangement for a rotor shaft of an electric machine comprises an essentially hollow cylindrical base body, a slip ring, a conductor element and a plastic overmolding.

[0014] The conductor element is electrically connected to the slip ring. The plastic overmolding extends at least partially through the shaft stub, fixing and holding the slip ring in position and at least partially surrounding the conductor element. Within the base body, the plastic overmolding is rotationally fixed to the body by a force-fit and / or form-fit connection. The plastic overmolding forms an undercut in the radial direction with respect to the base body to prevent axial displacement of the base body, slip ring, and conductor element relative to each other.

[0015] The advantage of this aspect lies in the fact that the plastic overmolding combines several functions. On the one hand, the overmolding fixes the slip ring and the conductor element relative to the base body. Axial fixation is achieved via the undercut, while circumferential fixation can be achieved through force-fit or form-fit, also via the undercut or other sections of the overmolding. On the other hand, the overmolding forms an insulating layer, so that the conductor element and the slip ring are electrically insulated from the base body. Because of the overmolding design, an undercut can be integrally formed with the base body and thus produced cost-effectively in the injection molding process, eliminating the need for additional components for fastening or fixing.The arrangement of the conductor element within the base body of the slip ring assembly for a rotor shaft is also particularly advantageous, since the arrangement of the conductor element described above provides radial support for the conductor element, at least partially within the plastic overmolding, especially in the case of centrifugal forces generated by high rotational speeds.

[0016] According to one embodiment, the conductor element is essentially L-shaped and has a first leg and a second leg. The first leg extends radially in the axial direction within the base body and is connected to the slip ring at its distal end. The second leg extends radially and forms a distal end radially outside the base body. P240742

[0017] - 4 -

[0018] Advantageously, the base body has a radial through-opening connecting the inside and outside of the base body, through which the second leg of the conductor element extends radially. It is particularly advantageous that the conductor element is spaced apart from the base body in the region of the second leg, so that it is not in direct contact with the base body. In particular, the through-opening is designed as a groove extending in the axial direction; other embodiments, such as a bore, are also possible.

[0019] According to a further embodiment, the base body forms a radially inwardly extending web which has a recess from a first axial side to a second axial side opposite the first axial side, through which the plastic overmolding extends in the axial direction. Furthermore, the plastic overmolding extends along the web on the first axial side beyond the recess in a radial and / or circumferential direction, forming an axial stop.

[0020] The radially inward-facing rib can advantageously have several recesses, which are particularly advantageously arranged uniformly in the circumferential direction. The resulting structure resembles the rotary magazine of a revolver and, in particular, has several recesses of the same size arranged on a common virtual circle, which in turn is aligned concentrically to the hollow cylindrical base body. The rib serves as an axial and circumferential stop for the plastic overmolding. In the axial direction, the stop is formed by the rib itself and the plastic overmolding extending radially and / or circumferentially along the first axial side of the rib. In the circumferential direction, the stop is formed by the plastic overmolding extending into the recess(s).

[0021] According to a preferred embodiment, the plastic overmolding on the web extends on the second axial side beyond the recess in a radial and / or circumferential direction, forming the undercut.

[0022] Advantageously, the plastic overmolding extending in the radial and / or circumferential direction on the second axial side of the web results in a material-bonded connection with the plastic overmolding extending in the axial direction through the recess, as well as the P240742 in the radial and / or circumferential direction.

[0023] - 5 - The plastic overmolding on the first axial side of the web has an undercut relative to the base body in the axial direction. The advantageous effect of this design lies in the simple manufacturing process using injection molding and the thus cost-effective fixation of the conductor element and slip ring to the base body. Advantageously, the first leg extends through the recess. The second leg extends through the undercut.

[0024] In other words, the conductor element is thus surrounded by the plastic overmolding, even within the recess, and is fixed in its spatial position. The plastic overmolding also forms an insulator around the conductor element, particularly within the recess. Furthermore, the plastic overmolding fixes and insulates the conductor element on the second axial side of the web, eliminating the need for additional components that would otherwise be required to fix and insulate the second leg of the conductor element. Preferably, the first leg extends beyond the recess into the undercut until it merges into the wider leg at an L-shaped connection point, the apex. This wider leg then extends radially within the undercut.

[0025] According to an advantageous embodiment, the base body has a further recess in the radially inward extending web, extending from a first axial side to a second axial side opposite the first axial side, wherein the further recess forms a cooling channel.

[0026] Advantageously, the plastic overmolding does not extend through the cooling channel in order to allow, on the one hand, the largest possible flow cross-section in the axial direction, and on the other hand, to realize a direct heat transfer from the cooling medium to the base body.

[0027] According to a second aspect, a rotor shaft of an electric machine comprises a hollow shaft section, a slip ring assembly according to the invention, and an axial fastening system. The slip ring assembly is inserted into the hollow shaft section up to an axial stop at one axial end. The axial fastening system comprises a first fastening element which is connected to the hollow shaft section and a second fastening element which is connected to the slip ring assembly and the first fastening element such that a P240742

[0028] - 6 - relative displacement of the hollow shaft section and slip ring arrangement to each other in the axial direction is prevented.

[0029] The advantageous effect of this aspect lies in the fact that, through the interaction of the radial stop and the fastening system, the hollow shaft section is connected to the slip ring assembly in the axial direction by means of the fastening elements. Particularly preferably, a shaft shoulder is inserted axially from the axial stop into the hollow shaft section, which serves for the radial centering of the slip ring assembly to the hollow shaft section. The radial stop is particularly preferably designed as a circumferential rib, which is suitable for absorbing compressive forces between the slip ring assembly and the hollow shaft section, which act as a counterforce due to tensile forces introduced into the fastening system.In particular, the tensile and compressive forces are selected such that a frictional connection is formed between the radial stop and the hollow shaft section in the circumferential direction, thus preventing rotation of the hollow shaft section relative to the slip ring assembly. Alternatively, rotation can also be prevented by positive locking elements that form a positive connection between the hollow shaft section and the slip ring assembly in the circumferential direction.

[0030] According to one embodiment, the first fastening element is a shaft nut with an external and an internal thread, which is screwed into the hollow shaft section by means of the external thread. The second fastening element is a screw with a screw thread and a screw head, wherein the screw head rests against the web and the screw thread engages in the internal thread of the shaft nut.

[0031] A particularly advantageous and cost-effective method is to mount the shaft nut inside the hollow shaft section using the external thread, as threading a hollow shaft is an established procedure. The shaft nut thus forms a stop within the hollow shaft section, similar to a rib. The two-part design allows the hollow shaft to be manufactured from a single piece of tubing, eliminating the need for complex machining. The rib forms a central recess that acts as a stop for the screw head on the first axial side. The screw head preferably rests directly against the rib. Alternatively, an intermediate element such as a washer, spring washer, or similar component (P240742) can be used.

[0032] - 7 -

[0033] Elements are inserted. Advantageously, the compressive force acting between the base body of the slip ring assembly and the hollow shaft section can be specifically adjusted via the screw and a correspondingly selected pitch in the screw thread as well as in the corresponding internal thread of the shaft nut.

[0034] According to a preferred embodiment, the base body has a bearing seat on a radial outer surface.

[0035] The advantageous effect of this design lies in the compact construction, since the slip ring arrangement can thus be considered as part of the rotor shaft via the base body, and forces can be transferred via the base body and its bearing seat as well as a bearing arranged on it into an adjacent housing or bearing shield or a comparable structure.

[0036] According to a third aspect, a method for manufacturing a slip ring assembly for a rotor shaft of an electric machine comprises the following steps:

[0037] • Providing an essentially hollow cylindrical base body forming a radially inward extending web which has a recess from a first axial side to a second axial side opposite the first axial side,

[0038] • Insertion of a conductor element which is essentially L-shaped and has a first leg and a second leg, wherein the first leg is arranged radially within the base body with play in the axial and / or radial direction to the recess and projects axially beyond the base body,

[0039] • Arrange a slip ring concentrically and axially spaced from the base body,

[0040] • Connect the conductor element to the slip ring so that the first leg is electrically connected to the slip ring.

[0041] • Overmolding of the base body, conductor element, and slip ring with a plastic overmolding, so that the base body, conductor element, and slip ring are positively and / or materially bonded to each other with the plastic overmolding. P240742

[0042] - 8 -

[0043] Advantageously, the previously described method allows for the cost-effective production of a slip ring assembly in which the plastic overmolding combines several functions. On the one hand, the plastic overmolding fixes the slip ring and the conductor element relative to the base body. On the other hand, the plastic overmolding forms an insulating layer, so that the conductor element and the slip ring are electrically insulated from the base body. Due to the design as a plastic overmolding, an undercut to the base body can be integrally formed and thus produced cost-effectively in the injection molding process, eliminating the need for additional components for fastening or fixing.The arrangement of the conductor element within the base body of the slip ring assembly for a rotor shaft is also particularly advantageous, since the arrangement of the conductor element described above provides radial support for the conductor element, at least partially within the plastic overmolding, especially in the case of centrifugal forces generated by high rotational speeds.

[0044] Particularly advantageous in this method is the insertion of two conductor elements and the arrangement of two slip rings, each electrically contacted in pairs. The conductor elements are advantageously positioned opposite each other in the circumferential direction. Thus, the bridge also has at least two recesses through which the first leg of each conductor element is arranged radially within the base body with axial and / or radial play relative to the respective recess.

[0045] For the purposes of the present invention, the term "plastic overmolding" refers to a component made of a plastic and / or a plastic-like material; alternatively, the component can be referred to as a plastic element. The plastic element can, for example, be made of an epoxy resin and / or acrylate-based potting compound. Likewise, the plastic element can be produced from granules using an injection molding process. It is particularly advantageous for the plastic element to be formed in one piece or monolithically. Furthermore, the plastic element can also be made of interlocking components made of a plastic commonly used in electrical applications, such as polyphenylene sulfide (PPS), polyphthalamides (PPA), polyetheretherketone (PEEK), and / or mixtures thereof, preferably consisting of one of these. P240742

[0046] - 9 - For the purposes of the present invention, the term "material-bonded connections" refers to connections achieved by methods in which the joining partners are held together by atomic or molecular forces. These are simultaneously non-disconnectable connections that can only be separated by destroying the bonding agents. Methods include, in particular, gluing, welding, soldering, or vulcanizing.

[0047] For the purposes of the present invention, positive locking connections are understood to be connections in which at least two connecting partners interlock. This prevents the connecting partners from separating, even without or when force transmission is interrupted. In particular, the positive locking can also be achieved by thermal action or pressure on one of the connecting partners, for example, by local melting, hot riveting, or extrusion.

[0048] The invention and its technical context are explained in more detail below with reference to the figures. It should be noted that the invention is not limited to the embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract aspects of the concepts illustrated in the figures and combine them with other elements and findings from the present description and / or figures. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. Identical reference numerals denote the same objects, so that explanations from other figures may be consulted for supplementary information. Terms such as "radial," "axial," or similar refer to the axis of rotation of the electrical machine, unless a different reference is explicitly used.Furthermore, for the sake of better readability of the figures, only individual or a few identical elements of a reference symbol may be provided.

[0049] It shows

[0050] Fig. 1 shows a section through a slip ring assembly, P240742

[0051] - 10 -

[0052] Fig. 2 shows a further section of the slip ring arrangement according to Fig. 1 ,

[0053] Fig. 3 shows a perspective projection of the slip ring arrangement according to Fig. 1.

[0054] Fig. 4 shows another perspective projection of the slip ring arrangement according to Fig. 1 ,

[0055] Fig. 5 shows a section of a rotor shaft comprising a slip ring arrangement,

[0056] Fig. 6 shows several process steps for manufacturing a slip ring assembly.

[0057] Figure 1 shows a section through a slip ring assembly 1 for a rotor of an electric machine. The section plane passes through the axis of rotation. The slip ring assembly 1 comprises two slip rings 3, which are arranged on a plastic overmolding 5 on the right side of the image plane and are coaxial with the axis of rotation. The plastic overmolding extends as a hollow shaft-like component in the axial direction, here to the left in the image plane, into a substantially hollow cylindrical base body 2 of the slip ring assembly up to a first axial side 71 of a web 7, which extends radially inwards into the base body. The web 7 forms two recesses 8 through which the plastic overmolding 5 extends further in the axial direction. The slip ring assembly also comprises two conductor elements 4, which are substantially L-shaped.A first leg 41 of each conductor element 4 is electrically connected at a distal end to a slip ring 3 and extends from the slip ring 3 axially within the plastic overmolding 5 through a recess 8 in the web 7. Since, in the present embodiment, both slip rings have at least an identical radius, each conductor element 4 has a radially pronounced bulge in the region of the first leg 41 to allow it to pass within the plastic overmolding 5 at a distance from the slip ring 3 connected to the other conductor element 4. The recesses 8 penetrate the web 7 from a first axial side 71 to a second axial side 72. At the second axial side 72, the plastic overmolding extends further axially and also, at least partially, circumferentially and radially, forming an undercut 6.In the area of ​​the rear- P240742.

[0058] - 11 -

[0059] In section 6, the first leg 41 of the L-shaped conductor element 4 transitions into the second leg 42 at its apex. The second leg extends radially outward beyond the base body 2 within the plastic overmolding 5. In the plane of the image, the base body has two axially oriented grooves at one end on the left, through which the conductor element 4, enclosed by the plastic overmolding 5, extends radially outward. The conductor element 5 forms a distal end that is outside the plastic overmolding 5 and is designed to be connected to a coil or winding of a rotor.

[0060] Figure 2 shows a further section of the slip ring assembly according to Fig. 1, wherein the section in the lower region of the image plane extends from the axis of rotation such that a further recess 81, which is formed in the web 7, lies in the section plane. In the present embodiment, the further recess 81 is lined on its walls by the plastic overmolding, so that a cavity remains which forms a cooling channel. Alternatively, the further recess can be free of the plastic overmolding 5. The cooling channel is permeable to a fluid which can be guided to the outside through radial through-openings in the plastic overmolding 5 to cool the slip rings 3.

[0061] Figure 3 shows a perspective projection of the slip ring assembly 1 according to Fig. 1. A bearing seat is formed on a radial outer side of the base body 5, which is particularly suitable for a fixed bearing. Furthermore, a shaft shoulder is shown in the left area of ​​the image plane, which forms a stop 113 in the axial direction.

[0062] Figure 4 shows another perspective projection of the slip ring arrangement according to Fig. 1. The second axial side 72 is visible in the area of ​​the web 7. In this embodiment, four further recesses 81 are formed in the web 7, of which only two are visible in the perspective projection.

[0063] Figure 5 shows a section of a rotor shaft 9 comprising a slip ring assembly according to Fig. 1. The section plane is chosen to be comparable to that of Figure 1. The rotor shaft 9 comprises a hollow shaft section 10 into which the slip ring assembly 1 is inserted up to the shaft shoulder forming the stop 113. P240742

[0064] - 12 -

[0065] Thus, the hollow shaft section 10 and the slip ring assembly 1 form an axial overlap area. In the present embodiment, the overlap area is designed to center the rotor shaft 9 relative to the slip ring assembly, so that the bearing seat 14 is centered on the rotor shaft with respect to another bearing seat (not shown). Furthermore, a first fastening element 111 is arranged in the hollow shaft section 10, which in this embodiment is a shaft nut 12 screwed into a corresponding mating thread in the hollow shaft section 10 by means of an external thread. A second fastening element 112 engages in the web and exerts a force on it, which acts in the direction of the hollow shaft section. In this embodiment, the second fastening element 112 is designed as a screw 13, the screw head of which rests against the first axial side 71 of the web.The screw thread engages in an internal thread of the shaft nut, thereby drawing the base body 2 over the axial stop against the hollow shaft section and applying corresponding force. The first and second fastening elements 111, 112 form a fastening system 11.

[0066] Figure 6 shows several process steps for manufacturing a slip ring assembly according to Fig. 1. The first step involves providing a substantially hollow cylindrical base body 2 forming a radially inwardly extending web 7, which has a recess 8 from a first axial side 71 to a second axial side 72 opposite the first axial side 71. This provision can preferably take place in a fixture or tool, which is used, for example, in a downstream injection molding process. In the specific embodiment, the additional recesses 81 are included; however, the process is also applicable to embodiments without these additional recesses. The second step involves inserting at least one conductor element 4, which is substantially L-shaped and has a first leg 41 and a second leg 42.The first leg 41 is arranged radially within the base body 2 with axial and / or radial play relative to the recess 8 and projects axially beyond the base body 2. In the present embodiment, two ladder elements are inserted accordingly. The ladder elements can be held by the same fixing or tool, so that the ladder elements 4 remain aligned with the base body 2 with the appropriate play. In a subsequent step, a slip ring 3 is arranged concentrically P240742.

[0067] - 13 - and axially spaced from the base body 2 at a distal end of the first leg 41 of each conductor element. The step of connecting the conductor element 4 to the slip ring 3, so that the first leg 41 is electrically connected to the slip ring 3, can take place immediately after the slip ring is positioned or at a later time. The slip ring(s) can be held by the same fixture or tool. Finally, the base body 2, the conductor element 4, and the slip ring 3 are overmolded to form a plastic overmolding 5, so that the base body 2, the conductor element 4, and the slip ring 3 are positively and / or materially bonded to each other by the plastic overmolding 5. In particular, the undercut 6 is formed by overmolding the base body 2. The overmolding is carried out in a suitable tool.

[0068] P240742

[0069] - 14 -

[0070] List of reference signs

[0071] Slip ring arrangement (1)

[0072] Basic body (2)

[0073] Slip ring (3)

[0074] conductor element (4)

[0075] Plastic overmolding (5)

[0076] Undercut (6)

[0077] Bridge (7)

[0078] Recess (8)

[0079] Rotor shaft (9)

[0080] Hollow shaft section (10)

[0081] Fastening system (11)

[0082] Shaft nut (12)

[0083] screw (13)

[0084] Bearing seat (14) first leg (41) second leg (42) first axial side (71) second axial side (72) further recess (81) first fastening element (111) second fastening element (112) axial stop (113)

Claims

P240742 - 15 - Patent claims 1. Slip ring arrangement (1 ) for a rotor shaft of an electric machine, comprising a substantially hollow cylindrical base body (2), a slip ring (3), a conductor element (4) which is electrically connected to the slip ring (3), a plastic overmolding (5) which extends at least partially through the base body (2) and fixes / holds the slip ring (3) in its position and at least partially surrounds the conductor element, wherein the plastic overmolding (5) is rotationally fixed to the base body (2) by a force-fit and / or form-fit connection, wherein the plastic overmolding (5) forms an undercut (6) in the radial direction to the base body (2) in order to prevent a relative displacement of the base body (2), slip ring (3) and conductor element (4) to each other in the axial direction.

2. Slip ring arrangement (1) according to claim 1, wherein the conductor element (4) is substantially L-shaped and has a first leg (41) and a second leg (42), wherein the first leg (41) extends radially in the axial direction within the base body (2) and is connected to the slip ring (3) at its distal end, and the second leg (42) extends radially and forms a distal end radially outside the base body (2).

3. Slip ring arrangement (1) according to claim 1 or claim 2, wherein the base body (2) forms a radially inwardly extending web (7) which provides a recess (8) from a first axial side (71) to one of the P240742 - 16 - has a second axial side (72) opposite the first axial side, through which the plastic overmolding (5) extends in the axial direction, and the plastic overmolding (5) extends on the web (7) on the first axial side (71) over the recess (8) in the radial and / or circumferential direction, forming an axial stop.

4. Slip ring arrangement (1 ) according to claim 3, wherein the plastic overmolding (5) on the web (7) on the second axial side (72) extends over the recess in a radial and / or circumferential direction forming the undercut (6).

5. Slip ring arrangement (1 ) according to claim 4, wherein the first leg (71 ) extends through the recess (8) and the second leg (72) extends through the undercut.

6. Slip ring arrangement (1 ) according to one of claims 3 to 5, wherein the base body (5) has a further recess (81 ) in the radially inward extending web (7) from a first axial side (71 ) to a second axial side (72) opposite the first axial side (71 ), wherein the further recess (81 ) forms a cooling channel.

7. Rotor shaft (9) of an electric machine, comprising a hollow shaft section (10), a slip ring assembly (1) according to one of claims 3-6, wherein the slip ring assembly (1) is inserted into the hollow shaft section (9) up to an axial stop (113) at an axial end, an axial fastening system (11) comprising, a first fastening element (111) which is connected to the hollow shaft section (10) and a second fastening element (112) which is connected to the slip ring assembly (1) and the first P240742 - 17 - Fastening element (111) is connected in such a way that a relative displacement of hollow shaft section (10) and slip ring arrangement (1) towards each other in the axial direction is prevented.

8. Rotor shaft (9) according to claim 7, wherein the first fastening element (111) is a shaft nut (12) with an outer and an inner thread, which is screwed into the hollow shaft section (10) by means of the outer thread, the second fastening element (112) is a screw (13) with a screw thread and a screw head, wherein the screw head rests against the web (7) and the screw thread engages in the inner thread of the shaft nut (12).

9. Rotor shaft (9) according to claim 7 or 8, wherein the base body has a bearing seat (14) on a radial outer surface.

10. Method for manufacturing a slip ring arrangement (1 ) for a rotor shaft (9) of an electric machine, comprising the following steps: Providing a substantially hollow cylindrical base body (2) forming a radially inward extending web (7) which has a recess (8) from a first axial side (71) to a second axial side (72) opposite the first axial side (71), Insertion of a conductor element (4) which is essentially L-shaped and has a first leg (41) and a second leg (42), wherein the first leg (41) is arranged radially inside the base body (2) with axial and / or radial play relative to the recess (8) and extends axially beyond the base body (2), Arranging a slip ring (3) concentrically and axially spaced from the base body (2), P240742 - 18 - Connecting the conductor element (4) to the slip ring (3) so that the first leg (41) is electrically connected to the slip ring (3). Overmolding of the base body (2), the conductor element (4) and the slip ring (3) forming a plastic overmolding (5), so that the base body (2), the conductor element (4) and the slip ring (3) are connected to each other by the plastic overmolding (5) in a form-fit and / or material-fit manner.

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