DE102021215044A1 - Electrical machine, machine component and method for manufacturing an electrical machine - Google Patents

Abstract

The invention relates to an electrical machine (12) having a stator (10) and a rotor (14), the stator (10) or the rotor (14) having teeth (18), the teeth (18) having windings (22) exhibit. It is proposed that the teeth (18) each have a tangentially extending support structure (64) on the tooth neck (28), which is provided to support the winding (22).

Description

The invention relates to an electrical machine according to the species of the independent claim. The invention also relates to a machine component for such an electrical machine and a method for producing such an electrical machine.

State of the art

In the case of EC external rotor motors, the fixed stator is typically wound with excitation coils. The electrical wiring of the coils is usually in the central area of the stator. Therefore, in the case of excitation coils designed as single-tooth coils, the input wire is led from an inner side of the tooth, the wire is typically wound around the tooth in several layers and the output wire is led away from the same inner side, so that the input and output wire are arranged in the same spatial area . For this reason, the coil must have an even number of layers, although a layer can also consist of just a single wire that completely spans the layer below. Typically, the layers are wound between the end stops of the tooth, so that the transition from one winding layer continuing in a radial direction to the next winding layer returning in the opposite radial direction is preferably arranged at one of the end stops. The transition from a continuous winding layer to the returning winding layer arranged above it is also referred to as a layer jump.

As a rule, the necks of the teeth are rectangular or slightly conical in shape in the axial plan view, so that the neck of the tooth through which the magnetic field flows has the same cross-sectional area as possible in the entire area of the winding. This results in a tapered groove between the teeth. For example, in the case of an internal stator, that is to say a stator with teeth extending radially outwards, the slot at the bottom of the slot has less space for winding wire than in an area further to the outside. In other words, the slot offers space further out for more winding layers than at the bottom of the slot. The goal of a good electrical machine is high power density and motor efficiency, which is achieved with a high copper fill factor, i.e. the highest possible amount of winding wire in a slot. Due to the conical geometry, a good copper fill factor is not possible with a winding in which the layer jump is only arranged at the end stops, since the areas of the slot that have more space for winding layers remain unfilled due to the limitation of the areas with less space for winding layers . Such unfilled areas can be filled with further turns, which can be applied by means of winding layers which are not completely wound from one end stop to the other end stop. For example, it may be necessary or desirable for two winding layers to be arranged at the bottom of the slot, while four winding layers are arranged at the radially outer end of the tooth. However, this necessitates a layer jump located somewhere between the end stops, also known as a central layer jump.

In the case of such a central layer jump, there is a risk—in contrast to a layer jump at an end stop—that the further layer structure can be significantly disrupted, for example turns of the next layer can slip off in an uncontrolled manner at the central layer jump. Due to the high wire tensile forces in a winding process, windings that have already been placed can be pulled out of the desired target position due to a winding that is misplaced. In particular, a misplaced winding can lead to non-ideal over-stretching and unintentional over-winding. This can have a very negative effect on the utilization of the installation space, and the winding process can also be severely disrupted, since if the windings are arranged incorrectly, the needle, which is wide compared to the wire, may no longer be able to dip properly into the stator slot.

Such an unordered layer structure is contrary to a good copper fill factor, in particular the resistance of the winding also deviates from the desired value, which has a disadvantageous effect on the motor function.

Disclosure of Invention

Advantages

The present invention describes an electrical machine having a stator and a rotor, the stator or the rotor having teeth, the teeth having windings. According to the invention, the teeth each have a tangentially extending support structure on the neck of the tooth, which is provided to support the winding. This has the advantage that individual turns of the winding can be suitably supported or fixed by the support structure in the area of a central layer jump. In this way, incorrect placement of windings in this area can be prevented. This makes it possible to provide an electrical machine with a high copper fill factor and a high power density and high efficiency.

An electrical machine should be understood to mean in particular an electric motor, preferably a rotary electric motor with a stator and a rotor. A stator is usually set up to accommodate excitation coils. During operation of the electrical machine, the excitation coils can generate a magnetic field that changes over time, in particular a rotary field, which is provided to cause the rotor to rotate. The rotor or the rotor of the electric motor can generally be fitted with permanent magnets, have current-commutated coils for generating the magnetic field, or be designed as a so-called squirrel-cage rotor of an asynchronous machine.

According to the present invention, the rotor can be designed as an inner rotor in an outer stator, or the rotor can be designed as an outer rotor around an inner stator. The windings around the teeth can be the excitation windings around the stator teeth or excitation windings around the rotor teeth. In summary, the present invention is advantageous for a machine component for an electrical machine, the machine component having teeth, the teeth having windings and, according to the invention, the teeth each having a tangentially extending support structure on the tooth neck, which is provided to support the winding and the machine component is a stator or rotor.

A winding, for example a tooth winding or a chord winding, is formed in particular by a conductor or wire which is wound at least once, preferably multiple times, around a pole which is aligned in a radial direction of the machine component. A winding preferably has a copper conductor or a copper wire. For example, the winding can be wound through two different slots. One turn of a wire of a winding preferably runs from a first face of the machine component through a first slot to the second face, then along the second face to a second slot, then through the second slot back to the first face and then along the first face back to the first Groove where the circulation of this whorl ends. The wire can then form a next turn with the same path around the machine component. A winding typically has a large number of turns. Provision is made for the winding to be energized during operation of the electrical machine and to form a magnetic field. The orientation of the pole of the magnetic field may coincide with a main radial extension direction of one of the teeth around which the winding is wound.

In the context of the present invention, the windings are preferably designed as toothed windings. A tooth winding is to be understood in particular as a winding which is wound around exactly one tooth and runs in sections through the two slots adjacent to the tooth. Such a winding is also referred to as a single-tooth winding. In the case of tooth windings, the pole of the magnetic field typically coincides with the axis of the main direction of extension of the tooth. A tooth winding is typically applied using the needle winding technique or with the help of baffles. In both cases, a free area is required in the slot into which the turns of the tooth winding do not reach, either as a winding path for the needle during needle winding or as a free space for inserting the guide plate.

A support structure is to be understood in particular as an elevation from the neck of the tooth in a tangential direction. In this context, a tangential direction should be understood to mean a circumferential direction or a direction aligned along an intended direction of rotation of the electrical machine. A tooth has a tooth neck that extends essentially along a radial direction of the electrical machine. The neck of the tooth has two inner surfaces, each of which faces an immediately adjacent tooth. In particular, the inner surfaces of the neck of the tooth delimit a groove between two teeth, at least in sections. In other words, an inner surface of the tooth neck extends essentially along the radial direction and along an axial direction of the electrical machine. An axial direction of the electrical machine is aligned in particular along an axis of rotation of the electrical machine. The support structure advantageously extends from at least one inner surface of the neck of the tooth, each of the two inner surfaces particularly preferably having a support structure.

The fact that a structure essentially extends in one direction or along one direction is to be understood in particular as meaning that a main direction of extension of the structure is preferably arranged parallel to the direction or at an angle of no more than 20°, preferably no more than 10°, particularly preferably no more than 5 ° deviates from a parallel arrangement.

The support structure can be formed in one piece with the machine component and/or the tooth. It is also conceivable that the support structure is made from a separate component which is at least non-positively connected to the machine component.

In this context, one-piece is to be understood in particular as being materially bonded, for example by a welding process and/or an adhesive process etc. and particularly advantageously molded, for example by being produced from a single cast and/or by being produced in a one-component or multi-component injection molding process. For example, in the case of a machine component having stacked laminations or electrical laminations, the support structure can be designed as a tangentially extending tongue of one or more—preferably axially directly adjacent—laminations. In particular, the radially extending tongues in the corresponding laminations can also be punched out during the manufacture of the laminations.

The fact that the support structure is provided to support the winding is to be understood in particular as meaning that the support structure, in particular due to its tangential extension, is designed in such a way that it secures at least one turn of the winding against displacement, in particular displacement in the radial direction .

Advantageous developments of the electrical machine are possible due to the features listed in the subclaims.

It is thus advantageous if the support structure is designed in the manner of a ramp, with a tangential extent of the support structure preferably increasing with the distance from the axis of rotation. In this way, a particularly uniform layer structure can be guaranteed. In particular, a support coil can be arranged on a region of the highest tangential extension of the support structure, with the coils in front of the support coil being guided tangentially continuously along the ramp up to the support coil. In this way, the support structure can be arranged particularly reliably, which in turn enables a precise and reliable jump in layers. Due to the fact that the support structure is designed in the manner of a ramp, a wire layer can be wound in a particularly orderly manner up to the support winding.

A support turn is to be understood in particular as a turn of a wire layer of a winding which protrudes tangentially with respect to the other turns of the wire layer. In this way, the next turn can be prevented from slipping off. A support turn is intended in particular to form a support structure for a turn of a subsequent wire layer. In particular, a primary support turn is intended to support a secondary support turn of a subsequent layer of wire. A support winding can advantageously support a layer jump.

In this context, a ramp-like structure should be understood to mean, in particular, a structure whose tangential extent increases, preferably continuously, along a radial direction. For example, the tangential extent of the ramp-like structure can change linearly as a function of the radial distance from an imaginary axis of rotation. Such a linear, ramp-like structure has a triangular shape, in particular in the radial plane or in a radial section. However, it is also conceivable for the ramp-like structure to be non-linear and for example to be convex or concave at least in sections. It is also conceivable that a ramp-like structure is largely linear and has substructures, for example that grooves are arranged on a largely linear ramp, for example for accommodating windings.

The fact that a ramp-like structure is largely linear is to be understood in particular as meaning that the tangential extent of the ramp-like structure can be described by a function of the radial distance from an imaginary axis of rotation, which is less than 15%, preferably less than 10%, more preferably less than 5% deviates from a linear function.

The electrical machine is further improved when the support structure is located at a radially inner portion of the tooth neck. In this way, the wire layers can be wound particularly evenly, starting from the radial inner section of the tooth neck. It is particularly advantageous if the input wire is arranged on the radial inner section of the neck of the tooth.

A radial inner section of the tooth neck should be understood to mean a section of the tooth neck which is arranged radially closest to the imaginary axis of rotation. In a machine component with teeth pointing radially outwards, for example an inner stator, the radially inner section of the tooth neck is arranged at the slot bottom or yoke. In a machine component with teeth pointing radially inwards, for example an outer rotor, the radial inner section is arranged on a tooth tip or on a tooth tip.

The electric machine is further improved when the support structure extends radially outward from an inner end stop to a radial support end, the support end being located in a central region of the tooth neck. In this way, a particularly uniform layer structure is possible.

An end stop is to be understood in particular as a delimitation of the tooth neck or a delimiting structure on the tooth neck, which delimits the winding radially. Typically, a tooth neck has a radially extending surface intended to receive the winding. The end stop is advantageously a structure extending out of the tooth neck or the surface of the tooth neck extending in the radial direction, preferably a structure extending in the tangential direction. An inner end stop is to be understood as meaning an end stop which is arranged radially on the inside of the tooth neck or tooth, in particular on a radial inner section of the tooth neck. An outer end stop should be understood to mean an end stop which is arranged radially on the outside of the tooth neck or tooth. In a machine component with teeth pointing radially outwards, for example an inner stator, the inner end stop can be formed by a groove base or a yoke and the outer end stop can be formed, for example, by a tooth head. In a machine component with teeth pointing radially inwards, for example an external rotor, the inner end stop can be formed by the tooth crest and the outer end stop, for example, by a groove base or a yoke. It is also conceivable that the end stop is formed on an insulation mask.

A support end of the support structure is to be understood in particular as the radially outer end of the support structure. The highest tangential extent of the support structure is advantageously arranged at the support end.

A central area is to be understood as an area of the tooth neck which is at a distance from the inner end stop which is between 35% and 65% of a radial winding space distance between the inner end stop and the outer end stop, preferably between 40% and 55%, particularly preferably between 45% and 50%.

A particularly stable layer jump is possible if the support structure has a radial extent of between 30% and 60% of a radial winding space distance between the inner end stop and an outer end stop of the tooth neck, preferably between 35% and 50%, particularly preferably between 40% and 45%.

It is also advantageous if the support structure assumes a support maximum with a maximum tangential extension at a radial support end, in particular with the radial support end being arranged in a central area of the tooth neck. In this way, it is possible to securely position a support winding that supports a central layer jump. The support winding is advantageously arranged at the support maximum, which enables particularly reliable support of subsequent windings due to the tangential elevation of the support maximum.

A particularly advantageous embodiment is when at least one insulation mask is arranged between the teeth and the windings and the insulation mask has the support structure at least partially. This enables the support structure to be provided in a particularly simple manner. In this way it is not necessary to form the support structure directly on the base body of the machine component, for example the laminated core for the stator. In particular, it is possible to use the same base body for different machine components, with the support structure being able to be adapted to the machine component in each case with an individual insulation mask, in particular to the wire thickness of the respective windings.

An insulation mask is provided in particular to electrically insulate the windings from a base body of the machine component, which has the teeth and grooves and is typically made of a metal, in particular electrical sheet metal. An insulation mask is typically made of plastic and is placed on the base body of the machine components—for example pushed on in the axial direction—or molded on. An insulation mask is preferably designed in such a way that, when it is mounted on the machine component, it covers or largely covers at least one axial end face of a tooth.

The insulation mask is preferably a one-piece component which is provided to largely completely cover at least the axial end faces of all teeth on an axial end face of the machine component. The insulation mask advantageously largely completely covers the respective transition areas between the grooves and an axial end face of the base body of the machine component.

Typically, an electrical machine has two insulating masks, one for each of the two axial faces. Advantageously, an insulation mask has sections that extend in the radial direction or in a radial plane on an axial end face, which in the assembled state at least sectionally - preferably largely completely - cover the axial end faces of the teeth and optionally at least sectionally - preferably largely completely - cover an axial end face of a Yoke area of the machine component covered. Advantageously an insulating mask has areas extending in the axial direction into the grooves, which in the assembled state at least partially--preferably largely completely--cover the tooth necks, in particular the portions of the tooth necks which are aligned in the circumferential direction.

It is also possible for the insulation mask to be formed in several pieces or from several sections. For example, it is conceivable that a section of the insulation mask is intended to cover or largely completely cover an axial end face of a tooth.

In this context, one-piece is to be understood in particular as being materially bonded, for example by a welding process and/or an adhesive process etc. and particularly advantageously molded, for example by being produced from a single cast and/or by being produced in a one-component or multi-component injection molding process.

The fact that an area is largely completely covered is to be understood in particular to mean that the area is covered by at least 90%, preferably at least 95%, particularly preferably at least 98%.

In particular, the support structure can be molded onto the insulation mask. The support structure can in particular be formed in one piece with the insulation mask. It is also conceivable for the support structure to be manufactured from a separate component which is connected to the machine component and/or the insulation mask at least in a positive or non-positive manner, preferably with a material connection. For example, the support structure, in particular a support structure designed in the manner of a ramp, can have a metal element which is cast into the insulation mask, for example.

In a manufacturing process, the insulation mask is preferably applied to the base body of the machine component before the coil windings are wound on it. An insulation mask can be designed to simplify or support the winding process of the windings. The insulation mask is also sometimes referred to as a winding mask.

It has been found to be particularly favorable for uniform layer formation when a maximum tangential extent of the support structure is between 60% and 250% of a wire thickness of the windings, preferably between 80% and 200%, particularly preferably between 100% and 150%.

It is also advantageous if the winding has a first wire layer which rests directly on the neck of the tooth or on the insulation mask, with a coil input wire being arranged on a radially inner end stop and being wound radially outwards up to a radially outer end stop and a primary has a support winding which is wound around the support structure and protrudes tangentially from the first layer of wire, and that the winding has a subsequent second layer of wire which rests in sections on the first layer of wire and is wound radially inwards from the radially outer end stop to the primary support winding and the last turn of the second layer of wire rests against the primary support turn and forms a secondary support turn with the last turn, which protrudes tangentially from the second layer of wire. This special wire arrangement, in combination with the support structure, causes the windings to be locked in the desired position. This enables a winding which is particularly stable against the turns slipping, so that in particular a very uniform winding can be provided. In this way, one layer of wire lies on the radially inner end stop—the first layer of wire—and two layers of wire, the first layer of wire and the second layer of wire, lie on the radially outer end stop.

The stability of the winding can be further improved if the winding has a third wire layer that follows the second wire layer, which rests on the second wire layer and is wound radially outwards, starting from the secondary support winding, up to the radially outer end stop, and the winding has an adjoining fourth wire layer, which rests on the third wire layer and is wound from the radially outer end stop to the inner end stop and from the primary support winding to the inner end stop rests on the first wire layer, in particular the fourth wire layer having a coil output wire on the inner end stop . In this way, two layers of wire rest in particular on the radially inner end stop—the first layer of wire and the fourth layer of wire—and all four layers of wire lie on the radially outer end stop. In this way, the space available in the slot can be filled with windings in a particularly efficient manner.

In general terms, a particularly stable winding is possible if the winding has 4*n wire layers, where n is greater than one, and where the [4*k+2]th wire layer and [4*k+3]th wire layer where k assumes values from 0 to n-1, is wound between the outer end stop and the support structure or the [4*k+1]th support turn or [4*k+2]th support turn. In other words, the winding can come on in groups of four of the following wire layers are divided (the [4*k+1]th, [4*k+2]th, [4*k+3]th and [4*k+4]th wire layer), where respectively the first or [4+1]*k-th wire layer and fourth or [4*k+4]-th wire layer are wound between the outer end stop and the inner end stop and the two middle wire layers, i.e. the second or [ The 4*k+2]th wire layer and the third or [4*k+3]th wire layer are wound between the outer end stop and the support structure. In this way, 2*n wire layers lie against the inner end stop and 4*n wire layers against the outer end stop. This enables a stable, almost wedge-shaped winding to be wound, which can fill a slot particularly well.

The stability of the winding can be further increased if there is a winding spacing between the primary support winding and the winding arranged in front of it, which is between 70% and 110% of a wire thickness of the winding, preferably between 80% and 100%, particularly preferably between 85% and 95%. In this way, a winding gap is provided in front of the primary support winding, in which in particular a winding is provided for a subsequent layer of wire, in particular for the fourth layer of wire, which runs back to the inner end stop. In this way, the winding width can also be reduced in the area of the support winding, so that the winding assumes a wedge-shaped shape along the radial direction, which is advantageous for a good copper fill factor.

The formation of uniform layers can be further improved if the necks of the teeth have winding guide elements, in particular grooves, which in sections extend essentially in the tangential direction. In particular, the winding guide elements can be formed in a winding mask and/or on the support structure. In this way, the optimal position of the first wire layer is enabled, which is the basis for a good positioning of the following wire layers.

A machine component for an electrical machine according to the present invention is also advantageous, the machine component having teeth, the teeth having windings, characterized in that the teeth each have a tangentially extending support structure on the tooth neck, which is provided to support the winding . A machine component is to be understood in particular as a stator or rotor for an electrical machine.

A method for producing an electrical machine with a machine component or a machine component, in particular according to the present invention, is also advantageous, the machine component having teeth, the teeth each having a tangentially extending support structure on the tooth neck, which is provided for supporting a winding is, the winding being wound around a tooth, for which purpose a first wire layer is initially wound radially outwards, starting from a radially inner end stop of the neck of the tooth, to a radially outer end stop, so that a primary support winding is formed, which is wound around the support structure and protrudes tangentially from the first layer of wire, and that a second layer of wire is then wound in sections over the first layer of wire, with the second layer of wire being wound radially inwards from the radially outer end stop to the primary support winding and with the last winding of the second layer of wire at the primary support coil and forms a secondary support coil with the last coil, which protrudes tangentially from the second layer of wire. In this way, the risk of misplaced windings and thus non-ideal over-stretching and unintentional over-winding will be minimized. With a correct winding arrangement, a trouble-free winding process can also be made possible.

The method can be further improved if, after the second layer of wire, a third layer of wire is then wound, which rests on the second layer of wire and is wound radially outwards, starting from the secondary support winding, up to the radially outer end stop, and then a fourth layer of wire is wound, which rests on the third wire layer and is wound from the radially outer end stop to the inner end stop and rests on the first wire layer from the primary support winding to the inner end stop, in particular the fourth wire layer having a coil output wire at the inner end stop.

character list

• 1 eine schematische Darstellung einer elektrischen Maschine gemäß der vorliegenden Erfindung,
• 2a und 2b eine Detailansicht einer Wicklung aus dem Stand der Technik,
• 3 ein Wickelschema auf einem Zahn ohne Stützstruktur,
• 4 und 5 eine Isolationsmaske gemäß der vorliegenden Erfindung,
• 6 und 7 Detailansichten der Isolationsmaske der 4 und 5,
• 8 ein Wickelschema gemäß der vorliegenden Erfindung,
• 9 ein Detail einer Isolationsmaske eine Variante der Isolationsmaske gemäß der vorliegenden Erfindung,
• 10 und 11 eine Variante eines Stators gemäß der vorliegenden Erfindung ohne Wicklungen,
• 12 und 13 den Stator aus den 10 und 11 im bewickelten Zustand und
• 14 eine Detailansicht eines Zahns des Stators aus den 12 und 13.

Exemplary embodiments of the electrical machine are shown in the drawings and explained in more detail in the following description. Show it

• 1 a schematic representation of an electrical machine according to the present invention,
• 2a and 2 B a detailed view of a winding from the prior art,
• 3 a winding scheme on a tooth without a support structure,
• 4 and 5 an isolation mask according to the present invention,
• 6 and 7 Detail views of the isolation mask of 4 and 5 ,
• 8th a winding scheme according to the present invention,
• 9 a detail of an isolation mask a variant of the isolation mask according to the present invention,
• 10 and 11 a variant of a stator according to the present invention without windings,
• 12 and 13 the stator from the 10 and 11 in the wound condition and
• 14 a detailed view of a tooth of the stator from the 12 and 13 .

Description

The same parts are given the same reference numbers in the different design variants.

1 shows a schematic representation of an electrical machine 12 with a stator 10 and a rotor 14. 1 shows a view along an imaginary axis of rotation 16 of the electrical machine 12. For example, the rotor 14 is designed as an external rotor and the stator 10 as an internal stator. The stator 10 and the rotor 14 are machine components of the electrical machine 12. The stator 10 has twelve teeth 18, for example. The number of teeth 18 is irrelevant for the present invention; the machine component can have any number of teeth 18 . The teeth 18 extend outwards along an imaginary radial direction 20 . By way of example, each tooth 18 has a winding 22 which is designed as a tooth winding or as a single-number winding. A groove 26 is arranged between two teeth 18 that are adjacent in a circumferential direction 24 .

2a 1 shows a schematic detailed view of a tooth 18 of a machine component from the prior art to illustrate a winding 22 . 2 shows a section along a radial plane, for the sake of clarity only half a tooth 18 is shown, the tooth 18 being bisected in radial direction 20 by its imaginary axis of symmetry 20a. The tooth 18 has a tooth neck 28 on which the winding 22 is arranged. The tooth 18 has an insulation mask 30 which insulates the tooth 18 , in particular the tooth neck 28 , from the winding 22 .

At the radially outer end of the tooth 18 there is a tooth tip 32 which extends from the tooth neck 28 in the tangential direction or circumferential direction 24 . A yoke 34 is arranged at the radially inner end of the tooth 18, from which the tooth 18 with the tooth neck 28 extends radially outwards. A groove base 36 of the tooth 18 or of the associated groove 26 is arranged on the yoke 34 . The insulation mask 30 forms an inner end stop 38 for the winding 22 with a contour extending in the circumferential direction 24 , which end stop is arranged, for example, on the slot base 36 . The insulation mask 30 forms an outer end stop 40 for the winding 22 with a contour extending in the circumferential direction 24 , which is arranged on the tooth head 32 , for example.

The winding 22 in 2a has two wire layers 42, a first wire layer 42a and a second wire layer 42b. The first layer of wire 42a lies directly on the insulation mask 30 and runs from the inner end stop 38 to the outer end stop 40. The second layer of wire 42b is arranged on the first layer of wire 42a and runs from the outer end stop 40 back to the inner end stop 38. The turns 44b of the second Wire layer 42b lie on the windings 44a of the first wire layer 42a. The imaginary dashed winding line 46 illustrates the order in which the windings 44 and thus the wire layers 42 are arranged. Accordingly, the last turn 44a of the first wire layer 42a lies directly against the outer end stop 40, the first turn 44b of the second wire layer 42b is arranged tangentially on the last turn 44a of the first wire layer 42a. The transition from the first wire layer 42a to the second wire layer 42b, which is arranged at the end stop 40, represents a lateral layer jump 48.

This in 2a The winding scheme shown has the disadvantage that the space available in the slot 26 is not well filled by the winding 22 . The imaginary boundary line 50 marks the usable winding space of the slot 26. As can be clearly seen, the slot 26 has a largely conical shape in the illustrated section through the radial plane, while the winding 22 fills a rectangular area in the radial section due to the two wire layers 42. An unfilled winding space 52 remains.

2 B 12 illustrates an alternative winding scheme which makes better use of the winding space in the slot 26, that is to say fills it out more with turns 44. In 2 B is essentially the same tooth 18 from the same perspective as in 2a shown only with a different winding 22. The first layer of wire 42a begins as in the variant of FIG 2a with a coil input wire 54 at the inner end stop 38 and wound to the outer end stop 40 . For example, the first wire layer 42a has twelve turns 44a. Then there is a first lateral layer jump 48a at the outer end stop 40, which leads to the second wire layer 42b. Now the second wire layer 42b different than in 2a not fully wound to the inner end stop 38. In the present case, the second wire layer 42b is wound radially inwards up to a central area 56 of the tooth neck 28 or the insulation mask 30 . By way of example, the second wire layer 42b has five windings 44b. After the last turn 44b of the second wire layer 42b, a first central layer jump 58a leads into a third wire layer 42c, which is wound from the central region 56 to the outer end stop 40. The third layer of wire 42c rests on the second layer of wire 42b. For example, the first turn 44c of the third wire layer 42c is arranged on the penultimate turn 44b and penultimate turn 44b of the second wire layer 42b. For example, the third layer of wire 42c has four turns 44c. After the last turn 44c of the third wire layer 42c at the outer end stop 40, a second lateral layer jump 48b leads into a fourth wire layer 42d. The windings 44d of the fourth wire layer 44d wind radially inwards from the outer end stop 40 . The first windings 44d of the fourth wire layer 42d are arranged on the third wire layer 42c. The fourth wire layer 42d then has a second central layer jump 58b in the central area 56, from which the windings 44d of the fourth wire layer 42d rest on the first wire layer 42a. For example, the fourth wire layer 42d has two windings 44d, which rest on the third wire layer 42. At the second central layer jump 58b, the wire of the winding 22 skips a total of four turns 44c, 44b of the third wire layer 42c and second wire layer 42b and lies with its next—in this example third—turn 44d on the first wire layer 42a. The other windings 44d of the fourth wire layer 42d wind up to the inner end stop 38 and end with a coil output wire 60. The fourth wire layer 42d has a total of eight windings 44d, for example.

with the inside 2 B Winding 22 shown, the winding space of the slot can be better filled with turns 44. However, central layer jumps 58 are necessary here, which jump over several turns 44 located underneath. There is therefore a risk of the wire of winding 22 slipping off in an uncontrolled manner at the central layer jump 58.

3 shows a tooth 18 with a winding 22 with central layer discontinuities 58, which corresponds to the winding 22 of the variant in 2 B shown very similar. The tooth 18 is shown here to illustrate the course of the winding 22 at different stages A to D of the winding, with one wire layer 42 being completely wound in each stage. For the sake of clarity, the insulation mask 30 is not shown and only the tooth neck 28 with the winding 22 is shown. 3 shows a view along the axis of rotation 16 of the two axial end faces 62a and 62b of the tooth 18. For each stage A to D there is a view of a first axial end face 62a of the tooth 18 on the left-hand side of the figure 3 shown and for each stage A to D in each case a view of a first axial end face 62a opposite arranged second axial end face 62b on the right side of the 3 pictured.

In stage A, the first layer of wire 42a is completely wound from the inner end stop 38 to the outer end stop 40 . Then, at the outer end stop 40, there is a first lateral layer jump 48a to a first winding 44b of the second wire layer 42b. As can be clearly seen, the turns 44 on the second axial face 62b run largely perpendicular to the radial direction 20 or to the imaginary axis of symmetry 20a of the tooth 18. On the first axial face 62a the turns 44 run at an angle compared to an arrangement perpendicular to the radial direction 20. By way of example, a winding 44 winds or runs on the first axial end face 62a essentially perpendicularly to the radial direction 20 and has a course portion in the radial direction 20 . By way of example, a winding 44 runs on the first axial end face 62a with a length in the radial direction 20 which largely corresponds to a wire thickness of the winding 22 .

The second layer of wire 42b is then wound back in the direction of the inner end stop 38 . As can be seen clearly, the winding direction changes at the layer jump 48 into the second wire layer 42b. Thus, the first wire layer 42a is wound to the right relative to the radial direction 20 . The returning second wire layer 42b is wound on the left relative to the radial direction 20 . Therefore, the first turn 44b of the second layer of wire 42b overlaps with the last turn 44a of the first layer of wire 42a.

In stage B, the second wire layer 42b is wound up to a central area 56 and after a first central layer jump 58a the first winding 44c of the third wire layer 42c follows. The first winding 44c of the third wire layer 42c is arranged on the second wire layer 42b. As can be clearly seen, the winding direction of the winding 22 changes at the first central layer discontinuity 58a; the third wire layer 42c is wound to the right relative to the radial direction 20. The first turn 44c of the third layer of wire 42c therefore clearly crosses the last turn 44b of the second layer of wire 42b. At this point there is a risk of uncontrolled slipping of windings 44.

In stage C, the third layer of wire 42c has been wound from the central region 56 to the outer end stop 40 . Stage D shows the finished fourth wire layer 42d, which is wound to the left relative to the radial direction 20 and runs from the outer end stop 40 to the inner end stop 38. In this case, for example, the first two turns 44d of the fourth wire layer 42d lie on the third wire layer 42c, and the last four turns 44d of the fourth wire layer 42d largely lie on the first wire layer 42a. The third winding 44d of the fourth wire layer 42d runs through the second central layer jump 58b and in doing so crosses over three windings 44c of the third wire layer 42c. At this point, too, there is an increased risk of uncontrolled slipping of turns 44.

According to the invention, the turns 44 are stabilized by a support structure 64 . 4 12 shows an insulation mask 30a for a first axial end face 62a of a stator 10. The insulation mask 30a has a yoke section 66 for partially covering the yoke area of the stator 10. FIG. Tooth sections for insulating the teeth 18 of the stator 10 extend outwards from the yoke section 66 in the radial direction 20. The tooth sections each largely form the contours of the tooth 18, in particular of the tooth neck 28, the tooth crest 32 and the groove 26 or the groove base 36. Therefore, for the sake of convenience, the portions of the tooth portion of the insulating mask 30a covering each portion of the tooth 18 are given the same name and reference numeral. For example, the portion of the insulating mask 30a that covers the tooth tip 32 is also referred to as the tooth tip 32 for the sake of simplicity. For example, the insulation mask 30 or the stator 10 has eighteen teeth 18 .

5 12 shows an insulation mask 30b for a second axial end face 62b of a stator 10. The insulation mask 30b for the second axial end face 62b also has a yoke section 66 for partially covering the yoke area of the stator 10. Tooth sections for insulating the teeth 18 of the stator 10 extend outwards from the yoke section 66 in the radial direction 20. In addition, the insulation mask 30b has, for example, three molded-on conducting elements 68, which are used to guide the phase connections for the three phases of the electrical machine 12 for contacting power electronics are trained. For this purpose, each guide element 68 has two guide grooves for receiving the line wires of the respective phase.

6 shows the detailed view of a tooth 18 of the insulating mask 30, 6A from the isolation mask 30a of the first axial face 62a 4 and 6B from the isolation mask 30b of the second axial face 62b 5 . As can be clearly seen, the tooth 18 or the insulating masks 30 has a tooth neck 28 extending radially outwards from the yoke section 66 both on the first axial end face 62a and on the second axial end face 62b and one arranged at the radially outer end Tooth base 32. The insulating masks 30 advantageously have winding guide elements which are provided for guiding the winding 22. By way of example, the winding guide elements 70 are designed as grooves 70 which each extend essentially in the tangential direction or circumferential direction 24 on the respective axial end face 62 . In the exemplary embodiment, the winding guide elements 70 on the second axial end face 62b are formed parallel to the circumferential direction 24 or perpendicular to an axis of symmetry 20a of the tooth 18. The winding guide elements 70 on the first axial end face 62a are formed at an angle to the circumferential direction 24. By way of example, the groove 70 winds or runs on the first axial end face 62a essentially perpendicularly to the radial direction 20 and in this case has a portion running in the radial direction 20 . For example, the grooves 70 run on the first axial end face 62a with a length in the radial direction 20 which largely corresponds to a wire thickness 84 of the winding 22 .

The winding guide elements 70 or grooves 70 are formed on the tooth neck 28 and on the support structure 64 . Furthermore, the yoke section 66 on the first axial face 62a at the tooth 18 has a winding guide groove 72 which is intended to lead a coil output wire 60 away from the winding 22 of the tooth 18 or to lead a coil input wire 54 to the winding 22 of the tooth 18. In this way, in particular, connecting wires between windings 22 of two different teeth 18 can be routed particularly easily over the first axial end face 62a.

In 7 To illustrate support structure 64, tooth 18 is off 6A shown enlarged. in 7 In the illustrated exemplary embodiment, the support structure 64 extends outwards from the tooth neck 28 tangentially or in the circumferential direction 24 . By way of example, the support structure 64 has a ramp-like design. As can be clearly seen, a tangential extension 74 of the support structure 64 increases outwards in the radial direction 20 or with the distance from the axis of rotation 16 . For example, the support structure 64 is arranged directly on the inner end stop 38, in particular on a radial inner section of the tooth neck 28.

In the exemplary embodiment, the support structure 64 extends from the inner end stop 38 to a radial support end 76. The support structure 64 has a radial extent 78 which, for example, extends 43% from a radial winding space stood at 80. The winding space distance 80 is the distance in the radial direction 20 from the inner end stop 38 to the outer end stop 50 on the tooth neck 28. The radial extent 78 of the support structure 64 is measured in the exemplary embodiment in the radial direction 20 between the inner end stop 38 and the support end 76. In particular, the support end 76 is located in a central area of the tooth neck 28 .

For example, the support structure 64 has a support maximum 82 at the radial support end 76, which has a maximum tangential extension 74a. For example, the maximum tangential extent 74a is 240% of a wire thickness 84 of the windings 22. In the exemplary embodiment, the maximum tangential extent 74a of the support structure 64 is 30% of a tangential width 86 of the tooth neck 28. In alternative embodiments, it is possible that the maximum tangential extent 74a of the support structure 64 is between 10% and 40%, preferably between 15% and 35%, particularly preferably between 20% and 25% of a tangential width 86 of the tooth neck 28.

In the 7 The clearly recognizable grooves 70 or winding guide elements 70 have a groove width 88 which essentially corresponds to the wire thickness 84 of the winding 22 .

8th 1 illustrates how the coil 22 may be wound around a tooth 18 with a support structure 64 in accordance with the present invention. For this purpose, the tooth 18 is shown to illustrate the course of the winding 22 at different stages A to D of the winding, with one wire layer 42 being largely completely wound in each stage. For the sake of clarity, the insulation mask 30 is not shown and only the tooth neck 28 with the support structure 64 and with the winding 22 is shown. 8th shows how 3 , a view along the axis of rotation 16 of the two axial end faces 62a and 62b of the tooth 18. For each stage A to D there is a view of a first axial end face 62a of the tooth 18 on the left-hand side of the figure 8th shown and for each stage A to D in each case a view of a first axial end face 62a opposite arranged second axial end face 62b on the right side of the 8th pictured.

In stage A, the first layer of wire 42a is completely wound from the inner end stop 38 to the outer end stop 40 . Then, at the outer end stop 40, there is a first lateral layer jump 48a to a first winding 44b of the second wire layer 42b. The last turn 44a of the first layer of wire 42a resting on the support structure 64 is a primary support turn 90a. The primary support coil 90a is arranged at the support maximum 82, for example. In the exemplary embodiment, a winding spacing 92 is formed on the second axial end face 62b between the primary support winding 90a and the winding 44 arranged in front of it. For example, the winding spacing 92 is 90% of the wire thickness. The winding distance 92 forms a winding gap, which can accommodate windings 44 of the following wire layers 42 and can stabilize them, in particular windings 44d of the fourth wire layer 44d. In the exemplary embodiment, a coil spacing 92 is formed on the first axial end face 62a between the primary support coil 90a and the coil 44a arranged in front of it and the coil 44a arranged thereafter. As can be clearly seen, the turns 44 on the second axial face 62b run largely perpendicular to the radial direction 20 or to the imaginary axis of symmetry 20a of the tooth 18. On the first axial face 62a the turns 44 run at an angle compared to an arrangement perpendicular to the radial direction 20. By way of example, a winding 44 winds or runs on the first axial end face 62a essentially perpendicularly to the radial direction 20 and has a course portion in the radial direction 20 . By way of example, a winding 44 runs on the first axial end face 62a with a length in the radial direction 20 which largely corresponds to a wire thickness 84 of the winding 22 .

The second layer of wire 42b is then wound back in the direction of the inner end stop 38 . As can be seen clearly, the winding direction changes at the layer jump 48 into the second wire layer 42b. Thus, the first wire layer 42a is wound to the right relative to the radial direction 20 . The returning second wire layer 42b is wound on the left relative to the radial direction 20 . Therefore, the first turn 44b of the second layer of wire 42b overlaps with the last turn 44a of the first layer of wire 42a.

In stage B, the second layer of wire 42b is wound to a central portion 56 with the last turn 44b of the second layer of wire 42b bearing against the primary support wrap 90a of the first layer of wire 42a and forming a secondary support turn 90b.

In stage C, after a first central layer discontinuity 58a, the secondary support winding 90b is followed by the first winding 44c of the third wire layer 42c. The third layer of wire 42c is completely wound from the central area 56 to the outer end stop 40 . As can be clearly seen, the winding direction of the winding 22 changes at the first central layer discontinuity 58a; the third wire layer 42c is wound to the right relative to the radial direction 20. The first turn 44c of the third layer of wire 42c therefore clearly crosses the last turn 44b of the second layer of wire 42b or the secondary support winding 90b. How clearly too As can be seen, a further winding spacing 92 is formed in particular on the second axial end face 62b between the secondary support winding 90b of the second wire layer 42b, which is stabilized by the primary support winding 90a, and the first winding 44c of the third wire layer 42c.

Stage D shows the finished fourth wire layer 42d, which is wound to the left relative to the radial direction 20 and runs from the outer end stop 40 to the inner end stop 38. The first four turns 44d of the fourth wire layer 42d lie on the third wire layer 42c, for example, on the first axial end face 62a, and the last three turns 44d of the fourth wire layer 42d largely lie on the first wire layer 42a. The fifth winding 44d of the fourth wire layer 42d runs on the first axial end face 62a from the second central layer jump 58b and in doing so crosses two windings 44c of the third wire layer 42c and is supported by the secondary support winding 90b. The next coil 44d of the fourth layer of wire 42d is supported by both that of the primary support coil 90a and the secondary support coil 90b. As can be clearly seen on the second axial end face 62b, a winding 44d of the fourth wire layer 42a is accommodated in the winding spacing 92 between the secondary support winding 90b and the first winding 44c of the third wire layer 42c. Furthermore, by way of example, a further turn 44d of the fourth wire layer 42d is accommodated in the turn spacing 92 or turn gap between the primary support turn 90a and the turn 44a of the first wire layer 42a arranged in front of it.

9 12 shows a detailed view of the second axial end face 62b of the tooth 18 in winding stage A from FIG 8th . As can be clearly seen, the support structure 64 has a spacer 94 extending from the support structure 64 in the tangential direction 24 at the position between the primary support winding 90a and the turn 44a of the first wire layer 42a arranged in front of it. The spacer 94 has the advantage that a winding gap can be provided particularly easily. Advantageously, the spacer 94 has a winding guide element 70 or groove 70 which is intended to receive at least one turn 44 of later wire layers 42 .

10 shows an insulation mask 30a for a first axial end face 62a which is mounted on the stator 10 but has not yet been wound. The insulation mask 30a largely corresponds to the insulation mask 30a in FIG 4 and has a yoke portion 66 for partially covering the yoke area of the stator 10 . The insulation mask is placed on a stator base body 96 . The stator base body 96 is, for example, formed from laminated cores and coated. In the exemplary embodiment shown, the stator base body 96 is largely covered by the insulation mask 30a and is only visible in the radially inner area. Tooth sections for insulating the teeth 18 of the stator 10 extend outwards from the yoke section 66 in the radial direction 20. The tooth sections each largely form the contours of the tooth 18, in particular of the tooth neck 28, the tooth crest 32 and the groove 26 or the groove base 36.

11 12 shows the insulation mask 30b for a second axial end face 62b 5 mounted on the stators 10 and unwound. The insulation mask 30b for the second axial end face 62b also has a yoke section 66 for partially covering the yoke area of the stator 10 . The insulation mask is placed on the stator base body 96 . As in 10 the stator base body 96 is largely covered by the insulation mask 30a and is only visible in the radially inner area. Tooth sections for insulating the teeth 18 of the stator 10 extend outward in the radial direction 20 from the yoke section 66. On the second axial end face 62b, the insulation mask 30b has, for example, three integrally formed conducting elements 68, which are used to route the phase connections for the three phases of the electrical machine 12 are designed to make contact with power electronics. For this purpose, each guide element 68 has two guide grooves for receiving the line wires of the respective phase.

12 shows the stator from the 10 and 11 from the first axial end face 62a in the finished wound state. The copper wire windings 22 can be clearly seen. By way of example, the windings 22 are designed as toothed windings. As can be clearly seen, the coil output wire 60 from the winding 22 of a first tooth 18a is connected via a connecting wire 98 to the coil input wire 54 of the winding 22 of a second tooth 18b, with the first tooth 18a and the second tooth 18b being circumferentially connected 24 two more teeth 18 are arranged. The connecting wires 98 of all pairs of teeth 18a, 18b run tangentially along the yoke portion 66 of the axial face 62a of the insulation mask 30a.

13 shows the stator from the 10 and 11 from the second axial end face 62b in the finished wound state. Here, too, the windings 22 made of copper wire can be clearly seen. The contact lugs 100 for the phase connections for the three phases of the electrical machine 12 for contacting power electronics can be seen clearly. The conductor wires of the contacting lugs 100 run over the guide grooves of the guide elements 68.

14 shows the detailed view of a fully wound tooth 18 of the stator 12 and 13 , 14A from the first axial face 62a and 14B from the second axial face 62b. In 14A it can be seen how the coil input wire 54 merges into the first windings 44a of the first wire layer 42a. The first four windings 44a of the first wire layer 42a are arranged on the support structure 64, which is largely covered by the windings 44 in this figure. The fourth turn 44a of the first wire layer 42a is arranged at the support maximum 82 and forms the primary support turn 90a. In 14b The secondary support coil 90b of the second wire layer 42b can also be seen, which is arranged on the primary support coil 90a. The first turn 44c of the third layer of wire 42c is supported by the secondary support turn 90b. Two further windings 44c of the third wire layer 42c can be seen, the remainder of the third wire layer 44c is covered by four windings 44d of the fourth wire layer 42d. A following winding 44d of the fourth wire layer 42a runs through the second central layer jump 58b and, supported by the secondary support winding 90b, meets back on the first wire layer 42a on the radial inner section of the tooth neck 28. After a further winding 44d of the fourth wire layer 42d, the winding wire goes in the coil-out wire 60 over which crosses the coil-in wire on the first axial face 62a of the yoke portion 66 of the insulation mask 30a.

14B illustrates the second central layer discontinuity 58b viewed from the opposite second axial face 62b. As can be clearly seen, the turn 44d of the fourth wire layer 42d of the second central layer discontinuity 58b is supported by the secondary support coil 90b, with the turn 44d of the second central layer discontinuity 58b radially outwardly abutting the secondary support coil 90b. On the first axial end face 62a, the winding 44d of the second central layer jump 58b is rotated half a turn further and bears radially on the inside against the secondary supporting winding 90b. The subsequent turn 44d of the fourth layer of wire 42d is supported by the primary support turn 90a and is disposed in the turn gap between the primary support turn 90a and the preceding turn 44a of the first layer of wire 42a.

Claims (15)

Electrical machine (12) having a stator (10) and a rotor (14), the stator (10) or the rotor (14) having teeth (18), the teeth (18) having windings (22), characterized that the teeth (18) each have a tangentially extending support structure (64) on the tooth neck (28), which is provided to support the winding (22). Electrical machine (12) after claim 1 , characterized in that the support structure (64) is designed like a ramp, with a tangential extent (74) of the support structure (64) preferably increasing with the distance from the axis of rotation (16). Electrical machine (12) according to one of the preceding claims, characterized in that the support structure (64) is arranged on a radially inner section of the tooth neck (28). Electrical machine (12) according to one of the preceding claims, characterized in that the support structure (64) from an inner end stop (38) extends radially outwards to a radial support end (76), the support end (76) in a central Area of the tooth neck (28) is arranged. Electrical machine (12) according to one of the preceding claims, characterized in that the support structure (76) has a radial extent (78) which is between 30% and 60% of a radial winding space distance (80) between the inner end stop (38) and a outer end stop (40) of the tooth neck (28), preferably between 35% and 50%, particularly preferably between 40% and 45%. Electrical machine (12) according to one of the preceding claims, characterized in that the support structure (64) at a radial support end (76) assumes a support maximum (82) with a maximum tangential extension (74a), in particular the radial support end (76) is arranged in a central area of the tooth neck (28). Electrical machine (12) according to one of the preceding claims, characterized in that at least one insulation mask (30) is arranged between teeth (18) and windings (22) and the insulation mask (30) at least partially has the support structure (64). Electrical machine (12) according to one of the preceding claims, characterized in that a maximum tangential extent (74a) of the support structure (64) is between 60% and 250% of a wire thickness (84) of the windings (22), preferably between 80% and 200%, more preferably between 100% and 150%. Electrical machine (12) according to any one of the preceding claims, characterized characterized in that the winding (22) has a first wire layer (42a) which rests directly on the tooth neck (28) or on the insulation mask (30), with a coil input wire (54) being arranged on a radially inner end stop (38) and is wound radially outward to a radially outer end stop (40) and has a primary support coil (90a) wound around the support structure (64) and protruding tangentially from the first layer of wire (42a), and in that the coil (22) a subsequent second wire layer (42b) which rests in sections on the first wire layer (42a) and is wound radially inwards from the radially outer end stop (40) up to the primary support winding (90a) and with the last winding (44b) of the second Wire layer (42b) rests against the primary support coil (90a) and forms a secondary support coil (90b) with the last coil (44b), which protrudes tangentially from the second wire layer (42b). The electrical machine (12) according to the preceding claim, wherein the winding (22) has a third wire layer (42c) which follows the second wire layer (42b), which rests on the second wire layer (42b) and, starting from the secondary support winding (90b ) is wound radially outwards up to the radially outer end stop (40), and wherein the winding (22) has a subsequent fourth wire layer (42d) which rests on the third wire layer (42c) and from the radially outer end stop (40) to is wound to the inner end stop (38) and rests on the first wire layer (42a) from the primary support winding (90a) to the inner end stop (38), in particular with the fourth wire layer (42d) having a coil output wire (60) on the inner end stop (38 ) having. Electrical machine (12) according to the preceding claim, characterized in that the winding (22) has 4*n wire layers (42), where n is greater than one, and the [4*k+2]th wire layer (42b ) and [4*k+3]th wire layer (42c), where k assumes values from 0 to n-1, between the outer end stop (40) and the support structure (64) or the [4*k+1] -th supporting turn (90a) or [4*k+2]-th supporting turn (90b) is wound. Electrical machine (12) according to one of claims 9 until 11 , characterized in that between the primary support winding (90a) and the winding (44) arranged in front of it there is a winding spacing (92) which is between 70% and 110% of a wire thickness (84) of the winding (22), preferably between 80% and 100%, more preferably between 85% and 95%. Electrical machine (12) according to one of the preceding claims, characterized in that the tooth necks (28) have winding guide elements (70), in particular grooves (70) which extend in sections essentially in the tangential direction (24). Machine component (10, 14) for an electrical machine (12) according to one of Claims 1 until 13 , the machine component (10, 14) having teeth (18), the teeth (18) having windings (22), characterized in that the teeth (18) each have a tangentially extending support structure (64) on the tooth neck (28) have, which is provided to support the winding (22). Method for producing an electrical machine (12) with a machine component (10, 14) or a machine component (10, 14), in particular according to one of Claims 1 until 14 , wherein the machine component (10, 14) has teeth (18), the teeth (18) each having a tangentially extending support structure (64) on the tooth neck (28), which is provided for supporting a winding (22), the winding (22) is wound around a tooth (18), with a first wire layer (44a) being wound radially outwards starting from a radially inner end stop (38) of the tooth neck (28) to a radially outer end stop (40). so that a primary support coil (90a) is formed, which is wound around the support structure (64) and protrudes tangentially from the first layer of wire (42a), and that a second layer of wire (42b) is subsequently wound in sections over the first layer of wire (42a). whereby the second layer of wire (42b) is wound radially inwards from the radially outer end stop (40) up to the primary support coil (90a) and rests against the primary support coil (90a) with the last coil (44b) of the second wire layer (42b). and with the last turn (44b) forming a secondary support turn (90b) which protrudes tangentially from the second layer of wire (42b).

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