DE102021109441A1 - Stator and method of manufacturing a stator - Google Patents

Abstract

The invention relates to a stator (1) for an electrical machine, comprising a stator body (3) with a large number of stator teeth (4) distributed around the circumference and stator slots formed between the stator teeth (4) and extending through the stator (1) in the axial direction (7), stator windings (6) arranged radially one above the other being accommodated in the stator slots (7), and the stator slots (7) along their radial extent have a slot bottom (8) at their radially outer end and a slot opening (9 ) identify, wherein the groove openings (9) are closed by a groove sealing means (10), wherein the groove openings (9) are closed by a cylindrical blow-molded plastic film (13).

Description

The present invention relates to a stator for an electrical machine, comprising a stator body with a plurality of circumferentially distributed stator teeth and stator slots formed between the stator teeth and extending in the axial direction through the stator, with stator windings arranged radially one above the other being accommodated in the stator slots, and the Stator slots along their radial extent have a slot bottom at their radially outer end and a slot opening at their radially inner end, with the slot openings being closed by slot sealing means. The invention also relates to a method for manufacturing a stator.

Electric motors are increasingly being used to drive motor vehicles in order to create alternatives to internal combustion engines that require fossil fuels. Significant efforts have already been made to improve the suitability for everyday use of electric drives and also to be able to offer users the driving comfort they are accustomed to.

A detailed description of an electric drive can be found in an article in the ATZ magazine, volume 113, 05/2011, pages 360-365 by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold with the title: Highly integrative and flexible electric drive unit for electric Vehicles. This article describes a drive unit for an axle of a vehicle, which includes an electric motor that is arranged concentrically and coaxially with a bevel gear differential, with a switchable 2-speed planetary gear set being arranged in the power train between the electric motor and the bevel gear differential, which is also is positioned coaxially to the electric motor or the bevel gear differential or spur gear differential. The drive unit is very compact and allows a good compromise between climbing ability, acceleration and energy consumption due to the switchable 2-speed planetary gear set. Such drive units are also referred to as e-axles or electrically operable drive train.

In addition to purely electrically operated drive trains, hybrid drive trains are also known. Such drive trains of a hybrid vehicle usually include a combination of an internal combustion engine and an electric motor, and allow - for example in urban areas - a purely electric mode of operation with simultaneous sufficient range and availability, especially for cross-country trips. In addition, there is the possibility, in certain operating situations, to be driven simultaneously by the internal combustion engine and the electric motor.

In the development of electric machines intended for e-axles or hybrid modules, there is a continuing need to increase their power densities, so that the cooling of the electric machines required for this is becoming increasingly important. Due to the necessary cooling capacity, hydraulic fluids, such as cooling oils, have prevailed in most concepts for dissipating heat from the thermally stressed areas of an electrical machine.

Jacket cooling and winding overhang cooling are known, for example, from the prior art for cooling electrical machines using hydraulic fluids. While jacket cooling transfers the heat generated on the outer surface of the stator laminations into a cooling circuit, with end winding cooling the heat transfer takes place directly on the conductors outside of the stator laminations in the area of the winding overhangs into the fluid.

Further improvements are offered by separate cooling ducts, which can be integrated into the laminated core of the stator (see e.g. EP3157138 A1 ) as well as in the slot in addition to the conductors (see e.g. Markus Schiefer: Indirect winding cooling of highly utilized permanently excited synchronous machines with tooth coil winding, dissertation, Karlsruhe Institute of Technology (KIT), 2017).

Concepts are also known in which hydraulic fluid flows directly around the windings in order to increase the power density. Improved cooling with direct contact between the hydraulic fluid and the conductor in the slot is already known in principle from the prior art. For example, describes DE102015013018 A1 a solution for electrical machines with single-tooth winding, where the fluid flows directly around the windings that are wound around the teeth.

In electrical machines with indirect jacket cooling, the stator slot is sealed with a slot sealing wedge. This is pushed axially into the stator slot and usually does not have to perform a sealing function there. In order to transfer this principle to a directly cooled stator with sealing requirements, the slot sealing wedge of each individual stator slot would have to be reliably sealed at its two contact surfaces with the stator laminated core over the entire stator length towards the rotor space. On a conventional stator with, for example, 96 stator slots and a length of 110 mm, this entails a very high risk of leakage during operation. In addition, this design would be during assembly associated with considerable effort, for example by adding a sealant.

Stators are known from the prior art in which a circumferentially closed sealing element is used on the inside diameter of the stator, e.g. in the form of a tube. The radial thickness of this sealing element directly increases the electromagnetically effective air gap and thereby reduces the performance of the machine. It must be designed in such a way that under the radial pressure load during operation, which is mainly due to the pressure of the cooling medium, it does not exhibit any impermissible radial inward deformation, which could lead to a collision with the rotor. It is common here to use a GRP or CFRP tube, which is first manufactured as a single part and then pushed into the inside diameter of the stator. However, this embodiment has some disadvantages.

Due to the technology, the thickness of such a GRP pipe cannot be reduced at will. A minimum thickness is required to build up the glass fiber mats. In addition, there is a high risk of damage when handling a thin tube from the manufacture of individual parts to assembly in the stator. In addition, the GRP pipe is usually mounted on two seals outside the air gap between the stator and the rotor. In between, it has to support itself through its mechanical rigidity, since no "holding" normal forces are transmitted to the inside diameter of the stator. Depending on the diameter and length of the stator, the GRP pipe must therefore be designed with a corresponding thickness in order to have a sufficiently low radial deformation during operation and a sufficiently high buckling resistance due to its inherent rigidity. Likewise, a stiff, fiber-reinforced material must be selected, which is associated with comparatively high costs.

Finally, the can and the stator are initially delivered as individual parts subject to tolerances and then have to be joined by pushing the can into the stator. In order to ensure the joinability in a critical tolerance position, there are tolerance positions in which there is play between the inside diameter of the stator and the GRP tube. In addition to the tube thickness, this joint clearance also increases the electromagnetically effective air gap.

Based on this state of the art, it is the object of the invention to reduce or completely avoid the above disadvantages and to provide a stator with an alternative circumferentially closed sealing element which, compared to the usual solid tube, increases the electromagnetically effective air gap less and is easier to assemble and cheaper combined manufacturing costs. It is also the object of the invention to provide a stator for an electrical machine that has a high power density due to optimized cooling and an optimized electromagnetic configuration. Furthermore, it is the object of the invention to implement an improved method for producing a stator.

This object is achieved by a stator for an electrical machine, comprising a stator body with a plurality of stator teeth arranged distributed circumferentially and stator slots formed between the stator teeth and extending through the stator in the axial direction, stator windings arranged essentially radially one above the other being accommodated in the stator slots , and the stator slots along their radial extent have a slot bottom at their radially outer end and a slot opening at their radially inner end, the slot openings being closed by a slot sealing means, the slot openings being closed by a substantially cylindrical annular blow-molded plastic film.

The stator according to the invention thus has a peripherally closed sealing element, which is not pushed into the stator inner diameter as a solid individual part, but is introduced as a plastically deformable element by radial expansion. A tubular or bottle-shaped semi-finished product made of a plastic or composite material is preferably used for this purpose, with the outside diameter of the semi-finished product being selected to be smaller than the inside diameter of the stator, so that it can be pushed in without resistance. Blow molding, in particular extrusion or stretch blow molding, is used to form the peripherally closed slot closure means, which closes the stator slots as a cylindrical blow-molded plastic film.

In this way, a stator for an electrical machine can be realized with direct slot cooling, in which the stator windings, e.g. in the form of a wave winding, can be inserted radially from the inside into the stator slots. The stator therefore has stator slots that are open radially inward towards the inside diameter of the stator.

The blow-molded plastic film in the form of a cylindrical ring seals the stator slots or cooling channels, through which a generally liquid cooling medium flows during operation, radially inwards towards the rotor. The cooling medium, which is usually under pressure, is thus essentially full constantly kept in the stator space and cannot flood the rotor space.

Furthermore, due to the cylindrical ring-shaped blow-molded plastic film, the electromagnetically effective air gap can be kept very small and the performance of the electrical machine can thus be optimized.

The term "plastic semi-finished product" refers to the component to be blow-molded before or during the blow-molding process, while the term "blow-molded plastic film" defines the blow-molded component after the blow-molding process, so that a terminological distinction can be made between the corresponding component before, during and after blow-molding.

It is particularly preferable that the blow-molded plastic film also extends into the groove openings in the radial direction, as a result of which greater radial force absorption of the blow-molded plastic film can be made possible.

According to an advantageous embodiment of the invention, it can be provided that the plastic film closes the slot openings over their entire axial extension, so that a complete closing of the slot openings is realized.

According to a further preferred further development of the invention, it can also be provided that the slot openings each have an undercut on their opposite flanks in the circumferential direction, behind which a cylindrical blow-molded plastic film reaches, so that the blow-molded plastic film is particularly well radially fixed in the stator slots is.

The stator according to the invention is preferably designed for use in a radial flow machine. A stator for a radial flow machine is usually constructed cylindrically and generally consists of electrical laminations which are electrically insulated from one another and are constructed in layers and packaged to form laminated cores. Distributed over the circumference, grooves which run essentially parallel to the rotor shaft and accommodate the stator winding or parts of the stator winding are let into the electrical lamination.

Stator windings are let into the stator slots of the stator according to the invention. A stator winding is an electrically conductive conductor whose length is significantly greater than its diameter. In principle, the stator winding can have any desired cross-sectional shape. Rectangular cross-sectional shapes are preferred, since they can be used to achieve high packing densities and consequently high power densities. A stator winding made of copper is very particularly preferably formed. A stator winding preferably has insulation. To insulate the stator winding, for example, mica paper, which for mechanical reasons can be reinforced by a glass fabric carrier, can be wound in ribbon form around one or more stator windings, which are impregnated with a hardening resin. In principle, it is also possible to use a hardenable lacquer layer without mica paper in order to insulate a stator winding.

The stator according to the invention also has a stator body. The stator body can be designed in one piece or in multiple pieces, in particular in segments. A one-piece stator body is characterized in that the entire stator body is formed in one piece, viewed circumferentially. The stator body is generally formed from a large number of stacked, laminated electrical laminations, each of the electrical laminations being closed to form a circular ring. A segmented stator body is characterized in that it is made up of individual stator segment parts. The stator body can be made up of individual stator teeth or stator tooth groups, with each individual stator tooth or each individual stator tooth group being formed from a large number of stacked, laminated electrical laminations, with each of the electrical laminations being designed as a stator segment sheet metal part.

The stator body is preferably formed from one or more laminated cores of stator. A stator lamination stack is understood to mean a plurality of laminated individual lamination sheets or stator lamination sheets, which are generally made of electrical steel and are stacked and packaged one on top of the other to form a stack, the so-called stator lamination stack. The individual laminations can then remain held together in the laminated core by gluing, welding or screwing.

The stator teeth of the stator are preferably formed in the stator body. Stator teeth are components of the stator body which are designed as circumferentially spaced, tooth-like radially inwardly directed parts of the stator body and between their free ends and a rotor body an air gap for the magnetic field is formed. The gap between the rotor and the stator is called the air gap. In a radial flux machine, this is an essentially annular gap with a radial width that corresponds to the distance between the rotor body and the stator body.

The stator is in particular for use in an electrical machine within a Provided drive train of a motor vehicle. The electric machine is intended in particular for use within a drive train of a hybrid or all-electric motor vehicle.

In particular, the electrical machine is dimensioned in such a way that vehicle speeds of more than 50 km/h, preferably more than 80 km/h and in particular more than 100 km/h can be achieved. The electric machine particularly preferably has a power of more than 30 kW, preferably more than 50 kW and in particular more than 70 kW. Furthermore, it is preferred that the electrical machine provides speeds greater than 5,000 rpm, particularly preferably greater than 10,000 rpm, very particularly preferably greater than 12,500 rpm.

1. a. Bereitstellung eines zylinderringförmigen Statorkörpers mit einer Vielzahl umfänglich verteilt angeordneter Statorzähne und zwischen den Statorzähnen gebildeten, sich in axialer Richtung durch den Stator erstreckender Statornuten, welche entlang ihrer radialen Erstreckung an ihrem radial äußeren Ende einen Nutgrund und ihrem radial inneren Ende eine Nutöffnung ausweisen,
2. b. Einsetzen von Statorwicklungen in die Statornuten,
3. c. Einführen eines zylinderringförmigen schalenartigen Kunststoffhalbzeugs in den zylinderringförmigen Statorkörper,
4. d. Blasformen des Halbzeugs innerhalb des Statorkörpers , so dass das Halbzeug in radialer Richtung an die radial inneren Mantelflächen der Statorzähne plastisch verformt wird und die Nutöffnungen so durch das als zylinderringförmig blasgeformte Kunststofffolie ausgebildete Nutverschlussmittel verschlossen werden.

The object of the invention is also achieved by a method for producing a stator for an electrical machine, comprising the following steps:

1. a. Provision of a cylindrical ring-shaped stator body with a large number of stator teeth distributed around the circumference and stator slots formed between the stator teeth and extending through the stator in the axial direction, which along their radial extent have a slot base at their radially outer end and a slot opening at their radially inner end,
2. b. inserting stator windings into the stator slots,
3. c. Insertion of a cylindrical, shell-like plastic semi-finished product into the cylindrical, annular stator body,
4. i.e. Blow molding of the semi-finished product within the stator body, so that the semi-finished product is plastically deformed in the radial direction on the radially inner lateral surfaces of the stator teeth and the slot openings are closed by the slot sealing means designed as a cylindrical annular blow-molded plastic film.

The method according to the invention can provide a stator with an intended direct slot cooling, which can realize an optimized stator in a simple and cost-effective manner in terms of manufacturing technology.

On the one hand, the blow-molded plastic film has a very low minimum thickness for technological reasons. Because the plastic semi-finished product is formed directly in the stator, only a few handling processes are required. The thickness can be adjusted with sufficient accuracy in the forming process via the pressure during the blow molding and a possible calibration tool that is advantageously used. The use of fiber braids with a technology-related minimum thickness is not absolutely necessary.

In order to allow an improved radial force absorption of the blow-molded plastic film, the semi-finished product can be blow-molded inside the stator body in such a way that the semi-finished product is plastically deformed in the radial direction on the radially inner lateral surfaces of the stator teeth and into the slot openings.

By introducing the internal pressure during the blow molding in the deformable semi-finished plastic product, for example with compressed air, this is inflated until it comes into contact with the inside diameter of the stator, ie with the radially inner lateral surfaces of the stator teeth. The inflated plastic semi-finished product lies against these tooth bases and forms an adhesive connection on the stator teeth with the stator body. Due to the adhesive connection of the heated plastic semi-finished product with the radially inner lateral surfaces of the stator teeth that occurs during blow molding, the compressive force can be supported over a large area on the stator by the coolant pressure in the stator slots during operation of the stator. In each stator slot, the penetration of the sealing element into undercuts on the stator lamination can additionally reinforce this supporting effect. The bending length between these support points is significantly less than the distance between the two external support points on both sides of the rotor, so that sufficient radial rigidity and buckling resistance can be achieved with significantly lower wall thicknesses and material qualities.

After the plastic semi-finished product has been applied to the radially inner lateral surface of the stator teeth, the plastic semi-finished product is further deformed in the further blow molding process in such a way that it is pressed in the radial direction through the slot openings into the stator slots, so that the blow-molded plastic film is secured in the circumferential direction, in particular with a positive fit in the stator body is Due to the simple plastic formability through radial expansion outwards, assembly in the axial direction does not have to be taken into account by the individual part tolerance. There is no additional play between the stator body and the blow-molded plastic film, which further increases the electromagnetic air gap in addition to the thickness of the blow-molded plastic film.

In a preferred embodiment, the circumferentially closed, blow-moulded plastic film on the inside diameter of the stator can also have the function of basic insulation between the stator and rotor take over. The circumferentially closed, blow-moulded plastic film on the inside diameter of the stator can take over this function with its original sealing function if the material and thickness are suitably selected, and is therefore a cost-effective embodiment.

This combination is particularly advantageous in applications with direct slot cooling; In principle, however, the method described above can also be used solely to fulfill an insulation function without taking the sealing function into account (e.g. also in applications with indirect jacket cooling or similar).

Both thermoformable thermoplastics and duroplastic materials in the form of e.g. prepregs can be used as materials. These can be used unreinforced or reinforced with glass fibers or modified with fillers. In the case of reinforcement with continuous fibres, i.e. fibers whose length roughly corresponds to the dimensions of the component, the orientation of the fibers must be adapted to the corresponding component in order to achieve sufficient deformability and later a good supporting effect. Fiber angles well below 90° are advantageous for deformability and well above 0° for optimized support. Thermoplastics offer the advantage of better processability, while duroplastic materials offer optimized rigidity, temperature resistance and adhesion to the stator. Electrically insulating glass/ceramic or polymer fibers are preferably used as fibers in order to avoid eddy currents in the air gap.

The axial connection of the blow-moulded plastic film can be identical to the connection in the slots of the stator by means of a circumferential groove in the housing in the area of the end windings, into which the plastic is molded. Alternatively, sealing by means of a radially acting O-ring, as is usual with cans according to the prior art, is possible, with a metallic support ring on the outer diameter improving the sealing effect here, particularly in a design with unreinforced plastics. In the case of cantilevered rotors, the blow-moulded plastic film could also be designed as a pot or bottle in order to achieve a complete seal on one side.

According to a further particularly preferred embodiment of the invention, provision can be made for the semi-finished plastic product to be heated before and/or during blow molding, so that it can be plastically formed in the heated state with reduced expenditure of force.

Furthermore, the invention can also be further developed such that before the semi-finished product is blow-molded, an adhesive is applied to the radially inner lateral surfaces of a plurality of the stator teeth and/or at least in sections to the lateral surface of the annular plastic semi-finished product facing the stator teeth. The advantage of this configuration is that the connection of the semi-finished plastic product or the blow-molded plastic film can be additionally reinforced with an adhesive.

In a likewise preferred embodiment variant of the invention, it can also be provided that the groove openings each have an undercut on their opposite flanks in the circumferential direction, behind which the cylindrical blow-molded plastic film engages after the blow molding of the semi-finished plastic product. As a result, in addition to the adhesive connection, mechanical radial support of the blow-molded plastic film on the stator can also take place.

It can also be advantageous to further develop the invention in such a way that, after the semi-finished product has been blow-molded, the inner diameter of the blow-molded plastic film is calibrated by a tool in the plastically formable state. With such a calibration tool, the inside diameter can be set with high shape and positional accuracy.

According to a further preferred embodiment of the subject matter of the invention, it can be provided that the blow-molded plastic film is UV-radiated to support and/or initiate curing, as a result of which sufficient rigidity and dimensional stability can be achieved in the blow-molded plastic film with shortened process times.

Finally, the invention can also be implemented in an advantageous manner in that the semi-finished plastic product is formed from a fiber-reinforced plastic, as a result of which the rigidity and dimensional stability of the blow-molded plastic film can be further improved.

The invention is explained in more detail below with reference to figures without restricting the general inventive idea.

• 1 einen Stator in einer perspektivischen Ansicht,
• 2 einen Stator in einem ersten Herstellungsverfahrensschritt in einer perspektivischen Axialschnittansicht und einer schematischen Querschnittsansicht,
• 3 einen Stator in einem zweiten Herstellungsverfahrensschritt in einer perspektivischen Axialschnittansicht und einer schematischen Querschnittsansicht,
• 4 einen Stator in einem dritten Herstellungsverfahrensschritt in einer perspektivischen Axialschnittansicht und einer schematischen Querschnittsansicht, und
• 5 ein Kraftfahrzeug mit einer elektrischen Maschine in einer schematischen Blockschaltansicht.

Show it:

• 1 a stator in a perspective view,
• 2 a stator in a first manufacturing process step in a perspective axial section view and a schematic cross-sectional view,
• 3 a stator in a second manufacturing process step in a perspective axial section view and a schematic cross-sectional view,
• 4 a stator in a third manufacturing process step in a perspective axial section view and a schematic cross-sectional view, and
• 5 a motor vehicle with an electric machine in a schematic block diagram.

the 1 shows a stator 1 for an electrical machine 2, comprising a stator body 3 with a plurality of circumferentially distributed stator teeth 4 and stator slots 7 formed between the stator teeth 4 and extending in the axial direction through the stator 1, with stator windings arranged radially one above the other in the stator slots 7 6 are included.

This is also well illustrated by the cross-sectional representations of the 2-4 visible. Along their radial extent, the stator slots 7 have a slot base 8 at their radially outer end and a slot opening 9 at their radially inner end, with the slot openings 9 being closed by slot sealing means 10 . In the ones shown 1 and 4 are the groove openings 9 closed by a cylindrical ring-shaped blow-molded plastic film 13, which extends in the radial direction into the groove openings 9, which is well based on the 4 is recognizable. The blow-moulded plastic film 13 closes the slot openings 9 over their entire axial extent, so that the stator 1 can be operated with a stator slot cooling system through which fluid can flow directly.

Again 4 is also easily removable, the groove openings 9 each have an undercut 12 on their opposite flanks 11 in the circumferential direction, behind which a cylindrical blow-molded plastic film 13 engages, so that the blow-molded plastic film 13 is mechanically secured in the radial direction.

The method for manufacturing the stator 1 is based on the 2-4 explained in more detail below.

Like in the 2 As shown, a cylindrical ring-shaped stator body 3 is initially provided with a large number of stator teeth 4 distributed around the circumference and stator slots 7 formed between the stator teeth 4 and extending in the axial direction through the stator 1, which along their radial extension at their radially outer end have a slot base 8 and have a groove opening 9 at their radially inner end.

The stator windings 6 are inserted into the stator slots 7 from the radially inner direction. After this, a cylindrical, shell-like plastic semi-finished product 14 is pushed into the cylindrical-ring-shaped stator body 3 from the axial direction, with the outer diameter of the plastic semi-finished product 14 being smaller than the inner diameter of the stator body 3. The axial extension of the plastic semi-finished product 14 is at least so large that after molding in the blow-molded plastic film 13 has an axial length which is at least as great as the axial extension of the stator slots 7, or in other words, the stator slots 7 are completely covered by the semi-finished plastic product 14. This state is in the 2 shown.

In a further process step, the semi-finished product 14 is then blow-molded inside the stator body 3, so that the semi-finished product 14 is plastically deformed in the radial direction into the slot openings 9 and the slot openings 9 are thus closed by the slot sealing means 10, which is designed as a cylindrical ring-shaped blow-molded plastic film 13 . When the semi-finished product 14 is blow-molded, a pressure is built up within the cylindrical interior space of the stator, which pressure presses the semi-finished plastic product 14 in the radial direction outwards in the direction of the stator slots 7 . For this purpose, for example, the end faces of the stator body 3 can be closed in a pressure-tight manner and compressed air can be applied to the interior. In principle, it would also be conceivable, alternatively or additionally, to generate a negative pressure in the stator slots 7 so that the semi-finished plastic product 14 is drawn towards the stator slots 7 in the radial direction. In order to reduce the pressure required for the deformation of the semi-finished plastic product 14, the semi-finished plastic product 14 can be heated before and/or during blow molding. For this purpose, for example, the pressurized compressed air can also be heated. During blow molding, the semi-finished plastic product 14 first nestles against the radially inner lateral surfaces 15 of the stator teeth 4 and forms an adhesive connection with them there. This state is in the 3 shown.

To improve adhesion, before the semi-finished product 14 is blow-molded, an adhesive can be applied to the radially inner lateral surfaces 15 of a plurality of the stator teeth 4 and/or at least in sections to the lateral surface 16 of the annular plastic semi-finished product 14 facing the stator teeth 4.

In the further course of the blow molding, the semi-finished plastic product 14 is then further outward in the radial direction through the groove openings 9 in Rich direction of the stator 7 pressed what in the 3 is shown. The groove openings 9 each have an undercut 12 on their opposite flanks 11 in the circumferential direction.

After the semi-finished product 14 has been blow-molded, the inner diameter of the blow-molded plastic film 13 is calibrated in the plastically formable state by a tool 17 which is guided axially through the stator interior, which is shown in the upper figure in FIG 4 is indicated.

The stator 1 can be designed in particular for an electric machine 2 within a hybrid or fully electrically operable drive train 19 of a motor vehicle 18, as is exemplified in FIG 5 is shown.

The invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be considered as limiting but as illustrative. The following patent claims are to be understood in such a way that a mentioned feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' feature, this designation serves to distinguish between two similar features without establishing a ranking.

Reference List

1

stator

2

electric machine

3

stator body

4

stator teeth

6

stator windings

7

stator slots

8th

groove bottom

9

groove opening

10

slot sealing means

11

flanks

12

undercut

13

plastic film

14

semi-finished plastic products

15

lateral surfaces

16

lateral surface

17

Tool

18

motor vehicle

19

powertrain

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 3157138 A1 [0007]
• DE 102015013018 A1 [0008]

Claims (12)

Stator (1) for an electrical machine, comprising a stator body (3) with a large number of stator teeth (4) distributed around the circumference and stator slots (7) formed between the stator teeth (4) and extending through the stator (1) in the axial direction, stator windings (6) arranged essentially radially one above the other are accommodated in the stator slots (7), and the stator slots (7) along their radial extent have a slot base (8) at their radially outer end and a slot opening (9) at their radially inner end , the slot openings (9) being closed by a slot closing means (10), characterized in that the slot openings (9) are closed by a blow-molded plastic film (13) which is essentially in the shape of a cylindrical ring. Stator (1) after claim 1 , characterized in that the blow-moulded plastic film (13) extends in the radial direction into the groove openings (9). Stator (1) after claim 1 or 2 , characterized in that the plastic film (13) closes the groove openings (9) over their entire axial extension. Stator (1) according to one of the preceding claims, characterized in that the slot openings (9) each have an undercut (12) on their opposite flanks (11) in the circumferential direction, behind which a cylindrical blow-molded plastic film (13) engages. Method for producing a stator (1) for an electrical machine, comprising the following steps: a. Provision of a cylindrical ring-shaped stator body (3) with a large number of stator teeth (4) distributed around the circumference and stator slots (7) formed between the stator teeth (4) and extending through the stator (1) in the axial direction, which along their radial extension at their radial have a groove base (8) at the outer end and a groove opening (9) at its radially inner end, b. Insertion of stator windings (6) into the stator slots (7), c. Inserting a cylindrical, shell-like plastic semi-finished product (14) into the cylindrical, annular stator body (3), i.e. Blow molding of the semi-finished product (14) inside the stator body (3), so that the semi-finished product (14) is plastically deformed in the radial direction on the radially inner lateral surfaces (15) of the stator teeth (4) and the slot openings (9) are in the form of a cylindrical ring blow-molded plastic film (13) formed groove closure means (10) are closed. procedure after claim 5 , characterized in that the blow molding of the semi-finished product (14) within the stator body (3) is carried out in such a way that the semi-finished product (14) in the radial direction on the radially inner lateral surfaces (15) of the stator teeth (4) and in the slot openings ( 9) plastically deformed into it. procedure after claim 5 or 6 , characterized in that the semi-finished plastic product (14) is heated before and/or during blow molding. Procedure according to one of Claims 4 - 7 , characterized in that before the semi-finished product (14) is blow-moulded, an adhesive is applied to the radially inner lateral surfaces (15) of a plurality of the stator teeth (4) and/or at least in sections to the lateral surface (16) of the annular plastic semi-finished product facing the stator teeth (4). (14) is applied. Procedure according to one of Claims 5 - 8th , characterized in that the groove openings (9) each have an undercut (12) on their opposite flanks (11) in the circumferential direction, behind which the cylindrical ring-shaped blow-molded plastic film (13) engages after blow-molding of the semi-finished plastic product (14). Procedure according to one of Claims 5 - 9 , characterized in that after the blow molding of the semi-finished product (14), the inner diameter of the blow-molded plastic film (13) is calibrated in the plastically formable state by a tool (17). Procedure according to one of Claims 4 - 8th characterized in that the blow-moulded plastic film (13) is UV-radiated to support and/or initiate curing. Procedure according to one of Claims 4 - 9 , characterized in that the plastic semi-finished product (14) is formed from a fiber-reinforced plastic.

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