Slotted locking elements for a rotor with chamfers

Abstract

The invention relates to a slot closure element (9) for a rotor (1) of an electric machine of a motor vehicle for closing a slot (6) of a rotor body (2) of the rotor (1), comprising: - a closure body (10) for placement in the groove (6), which has contact areas (14) for pressing against an inside of a radially outer groove boundary (6b) of the groove (6), - two axially projecting projections (16) on axially opposite end faces (17) of the closure body (10), each with a chamfer (18), wherein the chamfers (18) are designed to seal the groove (6) and to convert an axial force exerted on the projections (16) into a radial force acting on the closure body (10) to radially press the contact areas (14) against the inside of the radially outer groove boundary (6b).

Description

[0001] The invention relates to a slot closure element for a rotor of an electric motor vehicle for closing a slot in a rotor body of the rotor. The invention also relates to a rotor and a method for at least partially manufacturing a rotor.

[0002] The present work focuses on electric machines for electrified motor vehicles, such as electric or hybrid vehicles. Such machines typically have a stationary stator and a rotor rotatably mounted relative to the stator. The rotor contains magnetically generating components, such as permanent magnets or current-generating rotor windings, which are held by a rotor body, for example, a rotor lamination stack formed from axially stacked laminations. The rotor body typically has slots for receiving the magnetically generating components. It is known in the art to encapsulate the rotor with a potting compound to mechanically support the magnetically generating components against high centrifugal forces during rotor rotation. Before encapsulating the rotor, the slots are closed with slot closure elements.To seal the grooves, the groove sealing elements can be inserted axially into the grooves, for example by pressing them in or by loosely placing them. When pressing in the groove sealing elements, misalignment of the individual sheet metal lamellae, which affects the sealing contour, can cause chips to form on the sealing elements, which are made of materials such as hard plastic. When loosely placing the groove sealing elements into the grooves, leaks can occur, resulting in the grooves not being completely sealed and potting compound escaping from them.

[0003] The object of the present invention is to provide a rotor for an electric machine that is easy to manufacture and has reliably sealed slots.

[0004] This problem is solved according to the invention by a slot closure element, a rotor, and a method for manufacturing a rotor with the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description, and the figure.

[0005] A slot closure element according to the invention for a rotor of an electric motor vehicle serves to close a slot in the rotor body of the rotor. The slot closure element has a closure body for placement in the slot, which has contact areas for pressing against an inner side of a radially outer slot boundary. Furthermore, the slot closure element has two axially projecting projections, each with a chamfer, on axially opposite end faces of the closure body. The chamfers are designed to convert an axial force exerted on the projections into a radial force acting on the closure body, pressing the contact areas radially against the inner side of the outer slot boundary.

[0006] The invention also includes a rotor for an electric motor vehicle. The rotor comprises a rotor body with a plurality of grooves extending axially between two end faces of the rotor body. The rotor also includes magnetic field-generating components arranged in the grooves. Furthermore, the rotor includes two covers arranged on the end faces of the rotor body and attached to the rotor body. In addition, the rotor includes a groove closure element according to the invention for each groove, wherein the axial force is provided by the covers attached to the rotor body and the chamfers of the projections form a frictional connection with the covers.

[0007] In a method according to the invention for at least partially manufacturing a rotor according to the invention, the grooved rotor body is first provided. Then, the magnetic field-generating components are inserted into the grooves. The groove closure elements are placed into the grooves. The contact areas of the closure elements are pressed radially against the inner surfaces of the groove boundaries to seal the grooves by attaching the covers to the rotor body. The rotor can then be potted with a potting compound. For this purpose, at least one of the covers can have at least one filling opening for introducing the potting compound into the grooves.

[0008] The rotor can be used in an electric machine for a motor vehicle, which also has a stator that is fixedly mounted relative to the rotor. The electric machine is, in particular, a drive machine or traction machine for a motor vehicle designed as an electrified vehicle. The electric machine can, for example, be a current-excited synchronous machine (SSM). The electric machine is preferably an internal rotor machine in which the stator surrounds the rotor and the rotor is rotatably mounted within a hollow cylindrical stator body.

[0009] The rotor comprises the rotor body, which is preferably designed as a laminated core of axially stacked electrical steel laminations. The rotor body is preferably manufactured in a salient-pole configuration for a rotor of a separately excited electric machine and, for example, has a ring-shaped rotor yoke through which a rotor shaft passes. The rotor shaft is connected to the rotor body in a rotationally fixed manner. Salient poles are arranged circumferentially around the rotor yoke, each having a pole tooth projecting radially from the rotor yoke and, in particular, having parallel flanks, and a pole shoe radially adjacent to the pole tooth. A groove is formed between two adjacent salient poles, extending axially through the rotor body. In the case of the salient-pole rotor, the respective groove is tangentially oriented.The groove is bounded circumferentially by the facing tooth flanks of the pole teeth of the adjacent salient poles, which form lateral groove boundaries. Radially, each groove is bounded by an outer surface section of the rotor yoke, located between the two tooth flanks and forming a groove base or inner groove boundary, and by the inner surfaces of the pole shoes of the adjacent salient poles, which form the inner surface of the outer groove boundary. A pole gap between the pole shoes of the adjacent salient poles forms an access opening to the groove, through which a winding conductor, for example a wire, can be inserted into the groove when winding the pole teeth to form the rotor windings.

[0010] Each salient pole can carry a rotor winding or rotor coil. In the radial direction, the pole shoes support the rotor windings and prevent them from slipping off the pole teeth due to centrifugal force. Each rotor winding has two axial, slot-internal winding sections that bear against the tooth flanks of the corresponding pole tooth. Each slot can accommodate one axial winding section of a first rotor winding and one axial winding section of a second rotor winding wound around the adjacent pole tooth. In addition, each rotor winding has two end-face winding sections located on the axially opposite end faces of the rotor body. The end-face winding sections of all rotor windings form the winding heads. The rotor can also have star disks, with each star disk positioned between a winding head and an end face of the rotor body.The star-shaped disks serve, among other things, to stabilize the winding heads against rotationally induced centrifugal forces. The axial winding sections of the adjacent rotor windings, arranged in a groove, are spaced apart from each other in the circumferential direction, with a gap formed between each winding section. To stabilize the winding sections, this gap is filled with potting compound. For this purpose, the groove is first closed and sealed, at least in the radial direction, so that no potting compound escapes radially from the grooves when the rotor is potted.

[0011] To close and seal the grooves, groove closure elements are provided, each comprising a closure body. The closure bodies preferably consist of an elastic plastic, in particular an elastomer. The closure bodies are, for example, wedge-shaped and each has a radial section extending radially into the groove and a tangential section closing the groove, with the contact areas located at tangentially opposite ends of the tangential sections. The radial sections have, in particular, a substantially triangular cross-section, with axially and radially extending flanks of the radial section located adjacent to each of the axial winding sections. The tangential sections close the respective pole gap and thus the groove.The contact areas of the respective tangential section are arranged within the groove and radially adjacent to or abutting the inner sides of the radially outer groove boundaries. For example, the upper surface of the tangential sections has a fold or step at each tangentially opposite end, which forms the respective contact area.

[0012] The slot closure elements are inserted axially into the slots, primarily via one of the end faces of the rotor body. This insertion requires at least reduced force, thus minimizing friction between the contact surfaces of the closure elements and the inner surfaces of the pole shoes, and consequently preventing chip formation on the closure elements. Sealing of the slots therefore does not occur during insertion. Instead, the loosely inserted closure elements are pressed against the inner surfaces of the pole shoes by a radial force acting outwards, thereby sealing the slots.To exert the radial force, the slot closure elements each have two projections. A first projection extends axially from a first end face of the associated closure body, and a second projection extends axially from a second end face of the closure body. When the slot closure elements are installed in the slots, the closure bodies are positioned within the slots, and the projections extend axially out of the slots. This causes the projections to also extend beyond the end faces of the rotor body. Each projection has a chamfer or bevel. The bevel is designed such that the cross-section of the projections decreases axially from the respective end face of the closure body. The chamfers of the projections are directed radially inwards, i.e., towards the axis of rotation of the assembly and thus towards the rotor shaft.In other words, the chamfers of the protrusions face away from the contact areas of the associated closure body.

[0013] The rotor also features covers, which in particular serve as support structures for the rotor. One cover is located on one of the end faces of the rotor body and, for example, at least partially covers the associated winding head. The covers can also form heat sinks for cooling the magnetically generating components. Each cover can have a support ring arranged concentrically to the respective winding head, which extends from the end face of the rotor body at least over the axial height of the winding head and thus radially surrounds the winding heads. The support rings can, for example, be designed as metallic bandages, such as steel bandages.The covers can each have a lid section, with the lid sections axially overlapping the winding heads and the support rings extending axially between the respective end face and the respective lid section. The lid section and the support ring of a cover can be formed in one piece or in multiple pieces. The lid sections can, for example, have centrally located through-openings for the rotor shaft. At least one lid section can also have at least one filling opening for filling the potting compound for encapsulating the rotor. The covers, in particular the lid sections, are attached to the rotor body by means of an axial force. For example, the axial force for attaching the covers can be provided by screws. The covers can be screwed to the rotor body, for example, indirectly via the star washer or directly.

[0014] The locking elements are pressed radially towards the outer groove boundaries with the aid of the covers axially attached to the rotor body, so that the contact areas are pressed against the outer groove edges from the inside. This creates a radial force-fit connection between the groove locking elements and the rotor body. To provide this radial force-fit connection, an axial force-fit connection is formed between the groove locking elements and the covers. For this purpose, the undersides of the covers facing the end faces, for example, the cover areas, can have connecting elements with chamfers that run opposite to the chamfers of the projections. When the covers are axially attached to the rotor body, the chamfers of the connecting elements slide over the opposite chamfers of the projections. This creates a force-fit connection on both sides axially.A friction-fit connection in the form of a conical press fit is formed between the ring-shaped groove closure elements and the covers. This conical connection, or conical press fit, exerts a radial force on the groove closure elements, directed towards the inner sides of the groove boundaries.

[0015] The radial, force-fit connection between the slot closure elements and the rotor body, initially established by axial force, allows the slot closure elements to be loosely inserted into the slots. This prevents damage to the slot closure elements during insertion and ensures a reliable seal for the subsequent potting.

[0016] In a further development of the invention, the groove closure element comprises a metallic rod which is mechanically connected to the closure body, with the projections being the rod ends. The metallic rod, which extends through the groove when the groove closure element is assembled, serves in particular to stabilize the groove closure element. For example, the metallic rod and the closure body can be bonded together. For this purpose, the metallic rod can be overmolded with plastic during the manufacturing of the groove closure element, which, after curing, forms the closure body. The axial length of the metallic rod is greater than the axial length of the associated closure body, so that the axially opposite, chamfered rod ends project beyond the end faces of the closure body and thereby form the chamfered projections.For example, the metal rods are designed as round rods and thus, apart from the chamfered rod ends, have a circular rod cross-section.

[0017] The metallic rod can be designed as a heat conductor to dissipate waste heat from the magnetic field-generating components, for example, to the covers that act as heat sinks. In the case of a salient-pole rotor, the heat conductors are arranged in the slots between the internal winding sections of the two adjacent rotor windings. The heat conductors are designed to cool the magnetic field-generating components by absorbing their operational waste heat within the slot and dissipating it axially towards the rod ends and thus towards the end faces of the rotor body. For this purpose, it is advantageous if the end caps only partially encase the respective heat conductor for retention, so that the heat conductors have encased sections and exposed sections that absorb waste heat along the axial direction.The heat dissipated towards the end faces is transferred by the heat sinks to the covers, which act as heat sinks and are, for example, actively cooled. The metallic rods are thus advantageously multifunctional, serving to mechanically reinforce the closure elements, press them against the outer groove boundaries, and cool the magnetically generated components.

[0018] It is advantageous to arrange an insulating element at each rod end to prevent the formation of an electrically conductive path between the covers via the metallic rods. In the assembled state of the rotor, the insulating elements are positioned between the rod ends and the covers. The insulating element is made of an electrically insulating material, such as plastic, and prevents an electromagnetically unfavorable electrical connection between the covers via the metallic rods. In particular, the insulating element is made of a thermally conductive material to ensure reliable heat dissipation from the rods to the covers.Alternatively or additionally, the metallic rods are formed from at least two rod segments, arranged, for example, axially adjacent to each other, wherein the rod segments of each rod are mechanically connected by means of an electrically insulating and thermally conductive connecting element. For example, the connecting element can be a sleeve into which the rod segments are inserted from both sides and thus thermally and mechanically coupled, but electrically insulated. The rod segments can also be inserted into one another, electrically insulated from each other in the connection area, and joined, for example, by a positive locking mechanism and a material bond via the connecting element.

[0019] The embodiments and advantages presented with reference to the groove closure element according to the invention apply accordingly to the rotor according to the invention and to the method according to the invention.

[0020] Further features of the invention will become apparent from the claims, the figure, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown in the figure alone, can be used not only in the combinations specified, but also in other combinations or individually. The invention will now be explained in more detail with reference to a preferred embodiment and the drawing.

[0021] It shows the only figure Fig. 1 a perspective view of part of a rotor 1 of an externally excited electric machine, for example functioning as a drive machine.

[0022] The rotor 1 has a rotor body 2, which is formed, for example, from axially stacked and bundled sheet metal laminations. The rotor body 2 is manufactured here in a salient-pole configuration and has salient poles 3, each of which has a pole tooth 4 and a pole shoe 5. A slot 6 is formed between two salient poles 3, in which axial winding sections of two rotor windings formed by winding around the adjacent pole teeth 4 can be arranged. The opposing tooth flanks 7 of the pole teeth 4 form slot flanks and thus lateral slot boundaries 6a. Inner surfaces 8 of the pole shoes 5 form radially outer slot boundaries 6b. A gap between the pole shoes 5 of the adjacent salient poles 3 is closed by means of a slot closure element 9.

[0023] The groove closure element 9 has a closure body 10, which is arranged at least partially within the groove 6 and which is made, in particular, of an elastically deformable plastic. The closure body 10 has a radial section 11 arranged within the groove 6 and a tangential section 12 arranged in the gap. Tangentially opposite ends 13 of the tangential section 12 have contact areas 14 for pressing against the inner surfaces 8 of the pole shoes 5. The contact areas 14 are formed here by folds 15 of the ends 13, the folds 15 having a thickening 15a at their ends. In addition, the groove closure elements 9 have projections 16 which protrude from axially opposite end faces 17 of the closure bodies 10. The projections 16 each have a chamfer 18. The chamfer 18 faces away from the tangential section 12 and the contact areas 14. The chamfer 18 is directed radially inwards.The projections 16 can, for example, be formed as rod ends 19 of a metallic rod 20, which runs axially through the closure body 10 and thus through the groove 4 and which is designed, for example, as a heat-conducting rod or heat-conducting pin to dissipate waste heat from the rotor windings.

[0024] The radial force required to press the contact areas 14 against the inner surfaces 8 of the pole shoes 5 is converted from an axial force exerted on the chamfers 18 of the projections 16. This axial force can be provided, for example, by rotor covers which are placed on the end faces 21 of the rotor body 2 and fastened there, for example, by screws. For example, an underside of the covers facing the end faces 21 of the rotor body 2 can have chamfers opposite to those chamfers on the projections 18. These chamfers, arranged in a perpendicular manner, form a force-fit connection designed to convert the axial force, provided, for example, by the screw connection between the cover and the rotor body 2, into the radial force acting on the sealing elements 10.This causes the contact areas 14 to be elastically deformed and pressed against the groove boundary 6b from the inside to seal the groove 6.

Claims

[1] Slot closure element (9) for a rotor (1) of an electric machine of a motor vehicle for closing a slot (6) of a rotor body (2) of the rotor (1), comprising: - a closure body (10) for placement in the groove (6), which has contact areas (14) for pressing against an inside of a radially outer groove boundary (6b) of the groove (6), - two axially projecting projections (16) on axially opposite end faces (17) of the closure body (10), each with a chamfer (18), wherein the chamfers (18) are designed to seal the groove (6) and to convert an axial force exerted on the projections (16) into a radial force acting on the closure body (10) to radially press the contact areas (14) against the inside of the radially outer groove boundary (6b). [2] Groove closure element (9) according to claim 1, characterized in that the closure body (10) comprises a plastic, in particular an elastomer. [3] Groove locking element (9) according to claim 1 or 2, characterized by , that the closure body (10) is wedge-shaped and has a radial section (11) extending radially into the groove (6) and a tangential section (12) closing the groove (6), wherein the tangentially opposite ends (13) of the tangential section (12) have the contact areas (14). [4] Groove locking element (9) according to claim 3, characterized by , that an upper surface of the tangential sections (12) at the tangentially opposite ends (13) each has a fold (15) which forms the respective pressure area (14). [5] Slot closure element (9) according to one of the preceding claims, characterized by , that the groove closure element (9) has a metallic rod (20) which is mechanically connected to the closure body (10), wherein the projections (16) are rod ends (19) of the metallic rod (20). [6] Groove locking element (9) according to claim 5, characterized by , that the metallic rod (20) is designed as a heat-conducting rod for dissipating waste heat from at least one magnetic field-generating component of the rotor (10) arranged in the groove (6). [7] Groove locking element (9) according to claim 5 or 6, characterized by , that in order to prevent an electrically conductive path formed via the metallic rod (20) between two covers of the rotor (1), the metallic rod (20) is formed from at least rod segments which are mechanically connected by means of an electrically insulating and thermally conductive connecting element. [8] Groove locking element (9) according to one of claims 5 to 7, characterized by , that to prevent an electrically conductive path formed via the metallic rod (20) between two covers of the rotor (1), an insulating element is arranged at each of the rod ends (19). [9] comprising a rotor (1) for an electric machine of a motor vehicle: - a rotor body (2) with a plurality of grooves (6) extending axially between two end faces (21) of the rotor body (2), - magnetic field-generating components which are arranged in the slots (6), - two covers which are arranged and attached to the end faces (21) of the rotor body (2), - per groove (6) a groove closure element (9) according to one of the preceding claims, wherein the axial force is provided by the covers attached to the rotor body (2) and the chamfers (18) of the projections (16) form a force-fit connection with the covers. [10] Rotor (1) according to claim 9, characterized by, that the rotor body (2) is manufactured in a salient pole construction and has a plurality of salient poles (3), wherein a slot (6) for receiving magnetic field-exciting components in the form of rotor windings of the rotor (1) is formed between two adjacent salient poles (3) and wherein the radially outer slot boundaries (6b) of the slots (6) are formed by pole shoes (5) of the salient poles (3). [11] Rotor (1) according to claim 9 or 10, characterized by , that the covers have a lid area on the underside of which connecting elements are formed with a chamfer opposite to the chamfer (18) of the respective projection (16). [12] Method for manufacturing a rotor (1) according to any one of claims 9 to 11, comprising the steps: - Providing the rotor body (2), - Arranging the magnetic field-generating component in the slots (6), - Inserting the slot closure elements (9) into the slots (6), - radially pressing the contact areas (14) of the closure bodies (10) against the insides of the groove boundaries (6b) to seal the grooves (6) by attaching the covers to the rotor body (2).

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