Electric motor stator, electric motor and method for producing an electric motor stator

Abstract

The invention relates to an electric motor stator with a stator core having stator teeth and stator windings wound around the stator teeth to form coils, wherein the stator windings are formed from a winding wire with winding wire ends; with a printed circuit board to which the winding wire ends are electrically conductively contacted; wherein the stator core is surrounded by an electrically insulating material. The electric motor stator according to the invention is characterized by an annular or partially annular support placed on the stator core in the region of the winding wire ends, which support has electrically conductive terminals to which the winding wire ends are electrically conductively connected and contact points of the printed circuit board are electrically conductively connected.

Description

The present invention relates to an electric motor stator according to the preamble of claim 1, an electric motor comprising such an electric motor stator and a method for manufacturing such an electric motor stator.A generic electric motor is disclosed in DE 10 2021 100 304 A1. The rotor of the electric motor is provided with permanent magnets and an electric motor stator is arranged in the interior of the rotor. This is thus an external rotor. However, the present invention is also applicable to internal rotors in which the rotor is arranged radially inside the stator.The stator carries a number of windings on a stator core. When suitably controlled, the windings generate a magnetic field that exerts a rotational force on the rotor, such that the rotor rotates about an axis of rotation. The windings are usually wound in three phases and are accordingly provided with three electrical connections via which the windings can be connected to a control unit (ECU). The control unit is generally arranged on a printed circuit board of the electric motor stator.In order to avoid short circuits in the electric motor stator, a secure insulation of the stator windings with respect to components surrounding the latter is necessary. As a rule, an insulator, for example made of paper, plastic or of a paint, is provided for this purpose between the stator windings and the stator core. Furthermore, after the stator winding has been introduced onto the stator teeth, the stator core is encapsulated or cast around with an electrically insulating material, for example plastic, wherein the winding wire ends have to be held electrically conductive on the printed circuit board for their contacting.The electrically conductive contacting between the winding wire ends and the printed circuit board is complicated and cost-intensive. DE 10 2021 100 304 A1 therefore proposes that, when overmolding the stator core with the stator teeth and the stator windings on the top side of the stator core, exceptions be formed which extend with their longitudinal axes parallel to the longitudinal axis of the stator core. The receptacles are pocket-like and substantially rectangular in cross section with two longitudinal sides and two transverse sides. The openings of the pockets are located at the top on the side remote from the stator core. The longitudinal sides extend tangentially or in the circumferential direction of the longitudinal axis. On the side remote from the stator core, the receptacles each have a cut in the form of a slot on the inner longitudinal side. The slot extends parallel to the longitudinal axis and is provided for receiving the winding wire ends. The winding wire ends protruding from the front side of the stator core are bent outward in the radial direction and inserted into the respective slot of the receptacle. Then, in each receptacle, an insulation displacement contact is inserted into the opening from above. The insulation displacement contact has a clamping slot into which one or more winding wire ends can be accommodated as required. When the insulation displacement contacts are inserted into the pockets of the receptacles, the clamping slots are pushed onto the winding wire ends lying in the receptacles and are connected to the receptacles. As a result of sharp contact in the clamping slots, the insulation of the winding wire ends is cut through and electrical contact is made with the wire core of the winding wire. The insulation displacement contacts have two projections adjacent to the clamping slot region, which delimit the insertion path. The projections are each adjoined on the side remote from the clamping slot by a plug pin which is provided for the electrical contacting of the insulation displacement contact with the printed circuit board.A disadvantage of the embodiment shown is that the wire ends must be led out of the stator core through a tool and sealed. Such a seal in the injection mold is very difficult and is not reliable in practice. Furthermore, manual bending of the winding wire ends is necessary. Thus, the production of the illustrated electric motor stator is still comparatively complicated and not always reliable.The present invention is based on the object of specifying an electric motor stator and a method for producing such an electric motor stator, such that the production can be further simplified and preferably further automated.The object according to the invention is achieved by an electric motor stator having the features of claim 1 and a method for producing such an electric motor stator having the features of claim 14. The dependent claims describe advantageous and particularly expedient embodiments of the invention, and an electric motor according to the invention.An electric motor stator according to the invention has a stator core which comprises stator teeth and stator windings wound around the stator teeth to form coils. The stator windings are formed from a winding wire with winding wire ends. For example, the stator teeth are part of a star ring which is surrounded radially on the outside by a yoke ring. Accordingly, the stator teeth project radially outwards from an inner ring of the star ring and contact the yoke ring. However, it is also possible in principle to provide a ring radially on the outside with radially inwardly projecting teeth which bear radially on the inside against an inner yoke ring.The stator core preferably comprises a stack of sheets. This means that the stator teeth and in particular the star ring and optionally also the yoke ring are preferably formed from a stack of sheets, and therefore from individual sheet metal rings stacked one on top of the other, for example with a thickness of less than 0.5 mm.The electric motor stator according to the invention comprises a printed circuit board on which the winding wire ends are electrically contacted.The stator core is surrounded, in particular injection-molded and / or cast, by an electrically insulating material. The material is in particular plastic.According to the invention, in the region of the winding wire ends, in particular at an axial end of the stator core, an annular or part-annular carrier is placed on the stator core, wherein the carrier has electrically conductive terminals, to which the winding wire ends are electrically conductively connected and, in addition, contact points of the printed circuit board are electrically conductively connected.Instead of individual winding wire ends protruding out of the stator core in a disordered manner, the terminals in the carrier allow an exactly defined geometry which can be reliably sealed when applying the electrically insulating material to the stator core. Since the stator core is preferably surrounded, in particular injection-molded and / or cast around, with the electrically insulating material by the winding wire ends which are contacted at the terminals, a subsequent bending of the winding wire ends can be dispensed with according to a possible embodiment.In addition, the terminals can then be electrically connected, for example soldered, welded or clamped, to their contact points simply during the final assembly of the printed circuit board.The invention enables particularly process-friendly production of the electric motor stator, in particular if the stator windings are produced from a winding wire which is poorly solderable or weldable, for example from baking enamel wire. The terminals offer favorable sealing surfaces for an injection mold, into which the stator core with the mounted carrier and the terminals already electrically connected to the winding wire ends can be inserted in order to apply the electrically insulating material, in particular plastic.Preferably, the terminals are U-shaped and have a first leg and a second leg. This has the advantage of easy access in the axial direction from above. At least one winding wire end is connected to the first leg in each case, and at least one contact point of the printed circuit board is connected to the second leg in each case.The first legs are preferably fork-shaped and enclose the respective at least one winding wire end on three sides. The at least one winding wire end is thus inserted between the fork prongs of the first leg and is additionally surrounded by the base between the prongs.The second legs are preferably pin-shaped and penetrate the printed circuit board. This allows particularly easy electrical contacting between the terminals and the contact points of the printed circuit board.Preferably, the terminals are made of metal and the carrier comprises a base body made of an electrically insulating material, for example of plastic, into which the terminals are inserted. Particularly preferably, the terminals are encapsulated and / or encapsulated with the material of the base body, for example in an injection mold. Suitable holders for the targeted positioning of the terminals can be provided in the base body or in the injection mold. Such holders may cause openings in the carrier. A further embodiment provides for welding the terminals to the carrier with a suitable geometry, in particular by hot-caulking.According to an exemplary embodiment of the invention, the carrier has feet which project in the direction of the stator core and by means of which it is placed on the stator core. This allows a particularly exact positioning of the carrier axially and radially on the stator core to be achieved.The printed circuit board is placed on the carrier in particular on a side facing away from the stator core. The printed circuit board can be at least substantially planar, for example, and can rest on the carrier over the full surface or partially.The winding wire ends are preferably soldered or welded to the terminals. In this case, the soldered joints or welded joints can be sheathed, in particular injection-molded and / or cast, together with the carrier with an electrically insulating material, in particular with plastic. Preferably, only the terminals, in particular their second legs, then protrude from the electrically insulating material, so that the printed circuit board can be placed on and contacted with the terminals. Additionally or alternatively, it is also possible to apply the electrically insulating material after the circuit board has been placed on and the contact points of the circuit board have been contacted with the terminals, preferably in such a way that the soldered points or welded points of the contact points of the circuit board with the terminals are also covered with the electrically insulating material.Instead of the injection molding method for electrically insulating the stator core with the mounted carrier and in particular with the mounted printed circuit board, vacuum casting, or dripping or adhesive bonding of electrically insulating material, e.g. synthetic resin, can also be provided.The terminals, in particular their first legs, can preferably be contacted with the winding wire ends by resistance welding. For example, the terminals are made of tin-plated bronze.If the first legs are forked, the prongs of the fork can be compressed against the at least one enclosed winding wire end in order to ensure a secure contacting.The winding wire is made in particular of copper.An electric motor according to the invention has a rotor, for example with permanent magnets or with a rotor winding and an armature, and an electric motor stator according to the invention. The rotor is arranged radially on the inside or radially on the outside in or on the stator and is rotatable about an axis of rotation which coincides in particular with the longitudinal axis of the electric motor stator. When actuated, the stator windings in the electric motor stator generate a magnetic field which exerts a rotational force on the rotor, so that the rotor rotates about the axis of rotation. The stator windings are preferably wound in three phases and are accordingly provided with three electrical connections via which the stator windings can be connected to a control unit. The control unit is arranged, for example, on the printed circuit board of the electric motor stator.In the method according to the invention for producing an electric motor stator, at least the following steps are provided:forming the stator core with the stator teeth and inserting the stator windings onto the stator teeth such that the winding wire ends protrude from the stator core at an axial end;placing the support with the terminals inserted onto the axial end of the stator core;electrically connecting the winding wire ends to the terminals, in particular followed by electrically insulating injection molding around all the aforementioned components;placing the printed circuit board on the carrier; electrically connecting the contact points of the printed circuit board to the terminals.Preferably, the winding wire ends and / or the contact points are welded or soldered to the terminals.The carrier is preferably cast, in particular injection-molded, and the terminals can be encapsulated by injection molding with the material of the carrier, as described above. Additive production of the support by the 3D printing process is also possible.The soldered joints or welded joints of the winding wire ends are preferably sheathed, in particular injection-molded and / or cast, together with the carrier before or after the circuit board is placed on the carrier with an electrically insulating material.The electric motor stator is particularly preferably sheathed, for example insert-molded and / or cast-molded, with an electrically insulating material after its production, in particular over its entire circumference.The invention is to be described below by way of example with reference to an exemplary embodiment and the figures.The following are shown: FIG. 1 shows a stator core of an electric motor stator according to the invention during the mounting of the carrier; FIG. 2 shows the stator core from FIG. 1 during the mounting of the printed circuit board; FIG. 3 shows the stator core with the carrier placed on and the printed circuit board placed on for forming the electric motor stator according to the invention; FIG. 4 shows an enlarged detail view in the region of terminals of the electric motor stator from FIG. 3 ; FIG. 5 shows the introduction of the stator windings onto the stator teeth; FIG. 6 shows the stator core with inserted stator winding and attached yoke ring; FIG. 7 is a schematic view of terminals contacted with the winding wire ends.FIG. 1 shows a stator core 1 of an electric motor stator according to the invention, comprising stator teeth 2 which are arranged at a distance from one another in the circumferential direction about a longitudinal axis of the stator core 1. The stator teeth 2 project radially outwards from an inner ring 10 with respect to the longitudinal axis of the stator core 1 and are surrounded radially outwards by an outer ring 11. If the stator teeth 2 are embodied in one piece with the inner ring 10, this can also be referred to as a star ring, and the outer ring 11 as a yoke ring.The stator teeth 2 carry stator windings 3 wound into coils, made of a winding wire with winding wire ends 4 which protrude from the stator core 1 at an axial end 9.The inner ring 10, the stator teeth 2 and the outer ring 11 can be manufactured, for example, from stacked metal sheets, the stator windings 3 preferably from copper.In particular before the stator core 1 is injection-molded or else subsequently thereto, the carrier 6 is placed on the axial end 9 with the protruding winding wire ends 4. The carrier 6 comprises a base body 6.1, which is made of plastic, in particular by injection molding, wherein, for example, during injection molding, terminals 7 have been cast into the base body 6.1 or have also been subsequently inserted and thermally welded, in particular by hot caulking.In order to hold the terminals 7, which are U-shaped with a first leg 7.1 and a second leg 7.2, at the predetermined position during injection molding in the base body 6.1 of the carrier 6, the carrier 6 has position openings 12, through which a retaining pin, not shown in detail, has been pressed onto the terminals 7 during injection molding in order to hold them in predetermined axial positions.The support 6 has feet 6.2 with which it is placed on the stator core 1, in particular the outer ring 11, see FIG. 2.As can be seen in particular from FIG. 7, the terminals 7 are U-shaped and have a first leg 7.1, which is fork-shaped, and a second leg 7.2, which is pin-shaped. The first leg 7.1 and the second leg 7.2 are connected to one another via a web 7.3.The first leg 7.1 accommodates a winding wire end 4 and the second leg 7.2 penetrates a printed circuit board 5 placed on the carrier 6, see FIGS. 3 and 4.The second legs 7.2 are electrically contacted with the printed circuit board 5 at a contact point 8, not shown in detail.Before or after the circuit board 5 is placed on the carrier 6, the stator core 1 together with the carrier 6 and the electrical connection points between the winding wire ends 4 and the terminals 7 can be sheathed, in particular injection-molded and / or cast, with plastic, for example, by injection molding and / or dipping.FIGS. 5 and 6 show by way of example how the stator windings 3 are pushed onto the stator teeth 2 projecting radially outwards from the inner ring 10 and how the outer ring 11 is then placed onto the stator teeth 2 in such a way that the stator windings 3 are enclosed in the radial direction between the inner ring 10 and the outer ring 11 and each encompass a stator tooth 2. For example, three stator windings 3 are always pushed together onto three stator teeth 2.In order to insulate the stator windings 3 from the stator teeth 2, the inner ring 10 and the outer ring 11, an insulator 13 is provided, for example made of paper, which is initially opened radially outwards in order to allow the stator windings 3 to be pushed over the stator teeth 2 into the spaces between the stator teeth 2 enclosed by the insulators 13. The insulators 13 can then be closed radially on the outside, for example by folding, in order to cover the stator windings 3 also radially on the outside and to insulate them from the outer ring 11. These insulators 13 can also be seen once again from FIG. 7 in the closed state.Instead of paper, an injection-molded plastic insulator could also be pushed on in the wound state or a coating, in particular a paint, could be applied to stator windings 3 and / or the inner ring 10, the stator teeth 2 and the outer ring 11 as insulator 13.List of reference characters1 Stator core 2 Stator tooth 3 Stator winding 4 Winding wire end 5 Printed circuit board 6 Carrier 6.1 Base body 6.2 Base 7 Terminal 7.1 First leg 7.2 Second leg 7.3 Web 8 Contact point 9 Axial end 10 Inner ring 11 Outer ring 12 Position openings 13 InsulatorReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2021 100 304 A1 [0002, 0005]

Claims

Electric motor stator having a stator core (1) which has stator teeth (2) and stator windings (3) wound around the stator teeth (2) to form coils, wherein the stator windings (3) are formed from a winding wire having winding wire ends (4); having a printed circuit board (5) to which the winding wire ends (4) are electrically conductively contacted; wherein the stator core (1) is surrounded by an electrically insulating material; characterized by an annular or part-annular carrier (6) which is placed on the stator core (1) in the region of the winding wire ends (4) and has electrically conductive terminals (7) to which the winding wire ends (4) are electrically conductively connected and contact points (8) of the printed circuit board (5) are electrically conductively connected.Electric motor stator according to Claim 1, characterized in that the terminals (7) are U-shaped, having a first leg (7.1), to which in each case at least one winding wire end (4) is connected, and a second leg (7.2), to which in each case at least one contact point (8) of the printed circuit board (5) is connected.Electric motor stator according to Claim 2, characterized in that the first limbs (7.1) are fork-shaped and each enclose at least one winding wire end (4) on three sides.Electric motor stator according to either of Claims 2 and 3, characterized in that the second limbs (7.2) are pin-shaped and pass through the printed circuit board (5).Electric motor stator according to one of Claims 1 to 4, characterized in that the terminals (7) are produced from metal and the carrier (6) has a basic body (6.1) produced from an electrically insulating material, into which the terminals (7) are inserted.Electric motor stator according to Claim 5, characterized in that the terminals (7) are injection-moulded and / or injection-moulded with the material of the base body (6.1).Electric motor stator according to one of Claims 1 to 6, characterized in that the carrier (6) has feet (6.2) which project in the direction of the stator core (1) and by means of which it is placed on the stator core (1).Electric motor stator according to one of Claims 1 to 7, characterized in that the printed circuit board (5) is placed on the carrier (6) on a side facing away from the stator core (1).Electric motor stator according to one of Claims 1 to 8, characterized in that the winding wire ends (4) are soldered or welded to the terminals (7).Electric motor stator according to Claim 9, characterized in that the soldered joints or welded joints are surrounded, in particular injection-moulded and / or cast, together with the carrier (6) with an electrically insulating material, in particular with plastic.Electric motor stator according to one of Claims 1 to 10, characterized in that the terminals (7) are soldered or welded to the contact points (8).Electric motor stator according to Claim 11, characterized in that the contact points (8) are injection-moulded and / or cast around with plastic.Electric motor having a rotor and having an electric motor stator according to one of Claims 1 to 12.Method for producing an electric motor stator which is designed according to one of Claims 1 to 12, having the following steps: - producing the stator core (1) with the stator teeth (2) and inserting the stator windings (3) onto the stator teeth (2) such that the winding wire ends (4) protrude from the stator core (1) at an axial end (9); - placing the carrier (6) with the inserted terminals (7) onto the axial end (9) of the stator core (1); - electrically connecting the winding wire ends (4) to the terminals (7); - placing the printed circuit board (5) on the carrier (6); - electrically connecting the contact points (8) of the printed circuit board (5) to the terminals (7).Method according to Claim 14, characterized in that, after the winding wire ends (4) have been electrically connected to the terminals (7), the stator core (1), the stator windings (3), the winding wire ends (4), the carrier (6) and the terminals (7) are injection-moulded in an electrically insulating manner.Method according to claim 14 or 15, characterised in that the winding wire ends (4) and / or the contact points (8) are welded or soldered to the terminals (7).Method according to one of Claims 14 to 16, characterized in that the carrier (6) is injection-moulded and the terminals (7) are injection-moulded with the material of the carrier (6).Method according to one of Claims 16 or 17, characterized in that the soldered joints or welded joints of the winding wire ends (4) are sheathed, in particular injection-moulded and / or cast, together with the carrier (6) before or after the printed circuit board (5) has been placed on the carrier (6) with an electrically insulating material.Method according to one of Claims 14 to 18, characterized in that the electric motor stator is, after its production, in particular over its entire circumference, sheathed, in particular injection-moulded and / or cast, with an electrically insulating material.

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