DE102022100699A1 - Stator, electrical machine and method of manufacturing a stator - Google Patents

Abstract

The invention relates to a stator (1) for an electrical machine (2), comprising at least one stator body (3) with a large number of stator teeth (4) distributed around the circumference and formed between the stator teeth (4) and extending in the axial direction through the stator ( 1) extending stator slots (7), stator windings (6) which can be energized being 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 at their radially inner end (9), the slot openings (9) being closed by a slot closing means (10), and the slot closing means (10) being designed as a can (11), the can (11) having stator tooth contact elements (13 ) which rests against one of the stator teeth (4).

Description

The present invention relates to a stator for an electrical machine, comprising at least one 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, stator windings that can be energized being accommodated in the stator slots, and the stator slots along their radial extent at their radially outer end a groove bottom and their radially inner end a groove opening, wherein the slot openings are closed by a slot closure means, and the slot closure means is designed as a split tube.

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.

Stators are known from the prior art in which a circumferentially closed sealing element is used on the inside diameter of the stator, for example 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 inserted into the inside of the stator knife is inserted. 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.

Furthermore, the additional radial space required for the can increases the length of the air gap and thus significantly reduces the torque M of electrical machines. 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 at least one 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, with stator windings that can be energized 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 closure means, and the slot closure means being designed as a can, the can having stator tooth contact elements arranged in a carrier matrix, which on rest against one of the stator teeth.

The stator according to the invention thus allows the torque that can be generated within a given installation space to be increased considerably by reducing the air gap between the stator and a rotor. Furthermore, by designing the can as a composite component, the compressive strength and the functional principle of traditional cans can be retained. Also, the magnetic characteristics, such as maximum current, materials, number of pole pairs, etc., of the stator or the electrical machine do not necessarily have to be adjusted when using the proposed can. Furthermore, losses due to eddy currents in the can can be reduced to a minimum.

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 that 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.

Furthermore, it can also be preferred to design the stator as a stator for a claw-pole motor, in particular a claw-pole stepping motor.

Stator windings are let into the stator slots of the stator according to the invention. A stator winding includes electrically conductive conductors whose length is significantly greater than their 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.

The stator according to the invention also has at least one stator body. The stator can also be constructed from a plurality of stator bodies arranged in a row in an axial manner. The stator body can be made in one piece or in several pieces, in particular in a segmented manner. 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 laminated stator core is understood to mean a plurality of laminated individual laminations or stator laminations, 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 core. 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 that are designed as circumferentially spaced, tooth-like parts of the stator body that are directed radially inwards (inner rotor) or radially outwards (outer rotor) and between their free ends and a rotor body there is an air gap for the magnetic field and for the rotative Movement of the rotor is formed. The non-magnetic gap between the rotor and the stator is called the air gap. In the case of a radial flux machine, this is, for example, an essentially annular gap with a radial width that corresponds to the distance between the rotor body and the stator body.

The stator is particularly preferably provided for use in an electric machine within a 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 electric 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 electrical 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.

According to an advantageous embodiment of the invention, it can be provided that the can has a flat cylindrical surface towards a rotor of the electrical machine, which helps to keep the air gap between the stator and a rotor as small as possible.

According to a further preferred further development of the invention, it can also be provided that the stator tooth contact elements completely penetrate the carrier matrix of the can in the radial direction. It can hereby be achieved that the magnetic flux density can be further increased through the can and in the air gap between the rotor and a stator.

In principle, however, it would also be conceivable for the carrier matrix to completely or partially cover one or all of the stator tooth contact elements circumferentially on the lateral surface directed towards the rotor. For example, pockets can be formed that prevent or at least reduce direct contact between the rotor space and the stator tooth contact elements. This can be relevant in particular when media are exposed in the rotor space, which can lead to corrosion of the stator tooth contact elements, for example.

Furthermore, according to a likewise advantageous embodiment of the invention, provision can be made for the carrier matrix to be formed from a plastic, in particular from an epoxy resin, as a result of which the can can be designed to be particularly lightweight.

According to a further particularly preferred embodiment of the invention, provision can be made for the stator tooth contact elements to be formed from a metallic material, in particular from a laminated ferromagnetic metallic material. It is highly preferred that the material of the stator tooth contact elements corresponds to the material of the stator teeth. In this way, the effect can be achieved in particular that particularly high magnetic flux densities can be achieved in the air gap.

In principle, it would also be conceivable for the can to be formed from a carrier matrix made from martensitic steel and stator tooth contact elements made from ferritic steel.

Furthermore, the invention can also be further developed such that the basic shape of the stator tooth contact elements essentially corresponds to the basic shape of the stator teeth, as a result of which the contact surface between the stator teeth and the stator tooth contact elements can be optimally utilized. In particular, the stator teeth and the stator tooth contact elements are designed in such a way that they have a complete overlap in their contact area.

In a likewise preferred embodiment variant of the invention, it can also be provided that the can is formed by means of an adaptive manufacturing process. In this way it can be achieved that the can is flexibly adaptable to structural conditions of the stator.

It can also be advantageous to further develop the invention in such a way that the can has an essentially cylindrical basic shape, with an essentially constant cylinder wall thickness of 0.25-2.00 mm, preferably 0.75-1.5 mm.

The object of the invention is also achieved by an electrical machine comprising a stator according to one of Claims 1-8 and a rotor which is mounted such that it can rotate relative to the stator.

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 aufweisen,
2. b. Einsetzen von Statorwicklungen in die Statornuten,
3. c. Bereitstellung eines Nutverschlussmittels zum Verschluss der Nutöffnungen, wobei das Nutverschlussmittel als Spaltrohr ausgebildet ist, wobei das Spaltrohr in einer Trägermatrix angeordnete Statorzahnkontaktelemente aufweist,
4. d. Einsetzen des Spaltrohres in den Stator, so dass die Statorzahnkontaktelemente jeweils an einem der Statorzähne anliegen.

Finally, the object of the invention can be 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 multiplicity 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 bottom 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. Provision of a slot closure means for closing the slot openings, the slot closure means being designed as a can, the can having stator tooth contact elements arranged in a carrier matrix,
4. i.e. Insertion of the can in the stator so that the stator tooth contact elements are each in contact with one of the stator teeth.

This manufacturing process allows a stator with a particularly high torque output to be produced in a cost-effective and particularly safe manner.

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

• 1 eine elektrische Maschine in einer schematischen Querschnittsansicht,
• 2 einen Stator eines Klauenpolschrittmotors in einer perspektivischen Darstellung,
• 3 einen Stator eines Klauenpolschrittmotors mit einem ersten Spaltrohr in einer perspektivischen Darstellung,
• 4 einen Stator eines Klauenpolschrittmotors mit einem zweiten Spaltrohr in einer perspektivischen Darstellung,
• 5 ein Spaltrohr in einer perspektivischen Darstellung.

It shows:

• 1 an electrical machine in a schematic cross-sectional view,
• 2 a perspective view of a stator of a claw-pole stepping motor,
• 3 a perspective view of a stator of a claw-pole stepping motor with a first can,
• 4 a stator of a claw-pole stepper motor with a second can in a perspective view,
• 5 a can in a perspective view.

The 1 shows a stator 1 for an electrical radial flux machine 2, comprising at least one 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 that can be energized are in the stator slots 7 recorded. 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 . The slot closing means 10 is designed as a can 11 .

A "non-magnetic" can would significantly increase the length of the air gap and thus the magnetic reluctance. A less interlinked magnetic flux and a higher magnetic scattering would result.

The invention therefore proposes integrating the can 11 as a component of the stator 1 in order to reduce the length of the air gap. For this purpose, the can 11 has stator tooth contact elements 13 which are arranged in a carrier matrix 12 and rest against one of the stator teeth 4 in each case. This results in a type of radial extension of the stator teeth 4 in the radial direction toward the rotor 14 . As a result, the air gap between the stator 1 and the rotor 14 can be reduced to a minimum and the torque that can be generated by the stator can be increased.

This is based on the embodiments of 2-5 explained in more detail, which show a stator 1 for a claw-pole stepping motor. it understands sure that the explanations for this embodiment easily on the in 1 shown stator 1 for a radial flux machine 2 are transferrable.

2 shows a stator 1 formed from two stator bodies 3a, 3b, with claw-like, trapezoidal stator teeth 4, which are bordered by V-shaped grooves 17. The annular coils 18 of the claw pole are arranged at the base of these V-shaped grooves 17 . Basically the one from the 2 known stator 1 of a claw-pole stepping motor from the prior art, so that no further explanations are required here.

In the 3 is the one in the 2 shown stator 1 shown with cut stator teeth 4, so that the view of the ring coils 18 is free and they are easy to see.

From the 4 and 5 it can be seen that a can 11 has a flat cylindrical surface towards a rotor 14 of the electrical machine 2 . The can 11 has stator tooth contact elements 13 which are arranged in a carrier matrix 12 and rest against one of the stator teeth 4 in each case. This is in the 3 cannot be seen since the stator tooth contact elements 13 do not completely penetrate the carrier matrix 12 of the can 11 radially, so that the lateral surface directed towards the rotor 14 is formed only by the carrier matrix 12 .

In the 4 pass through the stator tooth contact elements 13, the support matrix 12 of the can 11 in the radial direction completely, so that this then - unlike in the embodiment of 3 , Are visible on the inner lateral surface of the can 11. The can 11 is designed in one piece and extends axially through the stator body 3a, 3b completely.

In the example shown, the carrier matrix 12 is made of a plastic, in particular an epoxy resin, and the stator tooth contact elements 13 are made of a metallic material, in particular a ferromagnetic metallic material. As can be seen particularly well from a synopsis of the 2 with the 4 can be seen, the basic shape of the stator tooth contact elements 13 corresponds essentially to the basic shape of the stator teeth 4, ie the stator tooth contact elements 13 and the stator teeth 4 are congruent and each stator tooth 4 is assigned a stator tooth contact element 13. As a result, metallic components are in contact with one another in the normal direction, which contributes in particular to good support and stability of the can 11 .

As in the 5 shown, the can 11 has an essentially annular basic shape, with an essentially constant cylinder wall thickness 14 of 0.25-2.00 mm, preferably 0.75-1.5 mm. On the outer surface of the can 11 facing away from the rotor 15, webs 16 are formed which protrude radially from this outer surface and engage in corresponding sections of the stator 1 in a form-fitting manner and thus bring about a defined and fixed position of the can 11 relative to the stator 1.

• Zunächst erfolgt eine Bereitstellung eines zylinderringförmigen Statorkörpers 3 mit einer Vielzahl umfänglich verteilt angeordneter Statorzähne 4 und zwischen den Statorzähnen 4 gebildeten, sich in axialer Richtung durch den Stator 1 erstreckender Statornuten 7, welche entlang ihrer radialen Erstreckung an ihrem radial äußeren Ende einen Nutgrund 8 und ihrem radial inneren Ende eine Nutöffnung 9 aufweisen. Nachfolgend wird ein Einsetzen von Statorwicklungen 6 in die Statornuten 7 durchgeführt. Hiernach erfolgt die Bereitstellung eines Nutverschlussmittels 10 zum Verschluss der Nutöffnungen 9, wobei das Nutverschlussmittel 10 als Spaltrohr 11 ausgebildet ist, wobei das Spaltrohr 11 in einer Trägermatrix 12 angeordnete Statorzahnkontaktelemente 13 aufweist. Abschließend erfolgt das Einsetzen des Spaltrohres 11 in den Stator 1, so dass die Statorzahnkontaktelemente 13 jeweils an einem der Statorzähne 4 anliegen.

To produce a stator 1 for an electrical machine 2, as in the 1 and the 3-4 shown, the following steps can be performed:

• First, a cylindrical ring-shaped stator body 3 is 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 their have a groove opening 9 at the radially inner end. Stator windings 6 are then inserted into stator slots 7 . This is followed by the provision of a slot closure means 10 for closing the slot openings 9 , the slot closure means 10 being designed as a can 11 , the can 11 having stator tooth contact elements 13 arranged in a carrier matrix 12 . Finally, the can 11 is inserted into the stator 1 so that the stator tooth contact elements 13 each rest against one of the stator teeth 4 .

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

cracking tube

12

carrier matrix

13

stator tooth contact elements

14

rotor

15

cylinder wall thickness

16

webs

17

grooves

18

toroidal coils

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 (10)

Stator (1) for an electrical machine (2), comprising at least one 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) which can be energized being 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 , wherein the slot openings (9) are closed by a slot closing means (10), and the slot closing means (10) is designed as a can (11), characterized in that the can (11) arranged in a carrier matrix (12) stator tooth contact elements (13) has, which rest on one of the stator teeth (4). Stator (1) after claim 1 , characterized in that the can (11) towards a rotor (14) of the electrical machine (2) has a flat cylindrical surface. Stator (1) according to one of the preceding claims, characterized in that the stator tooth contact elements (13) completely penetrate the carrier matrix (12) of the can (11) in the radial direction. Stator (1) according to one of the preceding claims, characterized in that the carrier matrix (12) is formed from a plastic, in particular from an epoxy resin. Stator (1) according to one of the preceding claims, characterized in that the stator tooth contact elements (13) are formed from a metallic material, in particular from a ferromagnetic metallic material. Stator (1) according to one of the preceding claims, characterized in that the basic shape of the stator tooth contact elements (13) essentially corresponds to the basic shape of the stator teeth (4). Stator (1) according to one of the preceding claims, characterized in that the can (11) is formed by means of an adaptive manufacturing process. Stator (1) according to one of the preceding claims, characterized in that the can (11) has a substantially cylindrical basic shape, with a substantially constant cylinder wall thickness (15) of 0.25-2.00 mm, preferably 0.75- 1.5mm Electrical machine (2) comprising a stator (1) according to one of the preceding claims and a rotor (14) rotatably mounted relative to the stator (1). Method for producing a stator (1) for an electrical machine (2), 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 their radially inner end, b. Insertion of stator windings (6) into the stator slots (7), c. Provision of a slot closure means (10) for closing the slot openings (9), the slot closure means (10) being designed as a can (11), the can (11) having stator tooth contact elements (13) arranged in a carrier matrix (12), i.e. Inserting the can (11) into the stator (1) so that the stator tooth contact elements (13) each rest against one of the stator teeth (4).

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