DE102022004802A1 - Method for producing a stator of an axial flow machine and stator - Google Patents

Abstract

The production of a stator of an axial flow machine is to be simplified. For this purpose, a method is provided for producing at least part of a stator of an axial flow machine by attaching a first joining section (21) made of a first material
to a first stator pole (11) of the stator, attaching a second joining section (22) made of a second material to a second stator pole (12) of the stator, wherein in a joined state of the first stator pole (11) and the second stator pole (12), the first joining section (21) overlaps with the second joining section (22) in the circumferential direction of the stator in an overlap region (5), wherein the second joining section (22) is located further out with respect to a center of the stator than the first joining section (21), wherein the second material is at least largely permeable to a predetermined laser wavelength, the second material is opaque to the predetermined laser wavelength, and irradiating the overlap region (5) with laser radiation (9) of the predetermined laser wavelength, whereby the first joining section (21) is welded to the second joining section (22).

Description

The present invention relates to a method for producing at least part of a stator of an axial flux machine. Furthermore, the present invention relates to a stator for an axial flux machine and an electrical axial flux machine itself.

Axial flux machines can be implemented, for example, as disc motors, whose rotor and stator are disc-shaped. The magnetic field runs parallel to the axis of rotation.

The stator poles of an axial flux machine are arranged in a circumferential direction. The individual teeth are usually insulated before the windings are applied. This insulation is achieved, for example, by overmolding the stator teeth with a plastic.

In connection with the manufacture of electrical machines, certain techniques such as laser welding, casting, potting and overmolding as well as other methods are well known. In this regard, reference is made to the publications JP2011193564 and WO 2011/037 087 It is also specifically stated there that the poles can be laser welded and/or overmolded for joining.

In the printed publications US2008/0315699 and EN 10 2016 213 110 It is mentioned that plastic parts are joined together by laser welding and attached to the engine.

The publication JP2006 325 345 describes a rotor whose plastic parts are joined together by laser welding. However, this is done with the aim of creating a media-tight, stable connection between the components of the rotor.

The object of the present invention is to simplify the manufacture of a stator for an axial flux machine.

According to the invention, this object is achieved by a method and a stator according to the independent claims. Advantageous developments of the invention emerge from the subclaims.

According to the invention, a method is therefore provided for producing at least part of a stator of an axial flux machine. The claimed method relates primarily to the joining of two stator poles and thus only to part of a stator of an axial flux machine. Of course, more than two or all stator poles of a stator can also be joined together in this way.

First, a first joining section made of a first material is attached to a first stator pole of the stator. In a similar way, a second joining section made of a second material is attached to a second stator pole of the stator. The joining sections serve to join the stator poles together. As a rule, a stator pole will not have just one joining section, but usually four joining sections, two each for connecting to an adjacent stator pole.

It is provided that when the first stator pole and the second stator pole are joined together, the first joining section overlaps with the second joining section in the circumferential direction of the stator in an overlapping area. In an (axial) plan view of the overlapping area, this means that the two joining sections lie on top of one another.

The second joining section is located further out in relation to a center of the stator than the first joining section. In particular, the second joining section should be freely accessible from the outside, while the first joining section can be covered by the second joining section. The distance from the center of the stator to the second joining section is therefore greater than the distance from the center to the first joining section.

The second material is at least largely transparent to a given laser wavelength, while the first material is opaque to the given laser wavelength. Two different materials are therefore used for the joining sections. Preferably, the second material of the outer second joining section is transparent and can also be referred to as a transmitter, while the material of the inner first joining section is opaque and can therefore also be referred to as an absorber.

Finally, the overlapping area is irradiated with laser radiation of the specified laser wavelength, whereby the first joining section is welded to the second joining section. Since the second, preferably transparent joining section is on the outside, the laser radiation can reach the first joining section and be absorbed there. This means that most of the energy, at least a large part, is absorbed in the inner first joining section, while no or only a small amount of the laser radiation energy is absorbed in the outer joining section. The energy of the laser radiation is sufficiently high to melt the first joining section and thus weld it to the second joining section. The second joining section may also be melted, at least in the surface area.

In an advantageous embodiment of the method according to the invention, the joining sections are welded in such a way that the overlapping area seals off a cavity or cooling space between the two stator poles in a media-tight manner. The pole teeth of the stator poles are usually surrounded by respective windings. Between the windings of two adjacent stator poles there is usually a small gap that can be used for the flow of coolant. This creates a cavity in which a cooling medium can flow. This cavity can be sealed in the axial direction by the two joining sections. To do this, it is usually necessary to weld the two joining sections along their entire radial extent (corresponds roughly to the radial extent of the stator poles). This naturally applies to both axial end faces.

In a further advantageous embodiment, the stator has a central axis that runs parallel to a respective main magnetic flux of the stator poles or the axial flux machine. This central axis corresponds to the axis that gives the axial flux machine its name. The second joining section is then arranged axially or radially outside the first joining section in relation to the central axis. This means that with axial laser irradiation, the second (transparent) joining section is first penetrated by the laser beam before it hits the axially inner opaque joining section and is absorbed there.

In a further embodiment, the stator poles are each provided with a winding before welding. In general, the teeth or laminated cores of the stator poles can be completely overmolded with the respective material or insulating material. The respective winding of the stator pole can then be pushed or wound onto this insulating material. Once the individual stator poles have been provided with their windings, they can be plugged together and finally welded.

According to an advantageous embodiment of the method according to the invention, the two stator poles are plugged together before welding, and the two joining sections lock into one another and/or form a positive connection. Locking into one another has the advantage that the stator poles already hold onto one another before they are welded. The locking into one another can be achieved by means of a (detachable) snap connection. For example, the stator poles can be plugged onto one another in the circumferential direction so that they lock into one another. However, other types of positive connection between the stator poles can also be selected. For example, neighboring stator poles can be plugged into one another using a tongue and groove principle, e.g. in the radial direction. In this case, for example, the groove represents one joining section and the tongue represents the other joining section. If the groove is transparent and the tongue is opaque, laser welding can also be implemented here.

The above-mentioned object is also achieved according to the invention by a stator for an axial flow machine, comprising a first joining section made of a first material on a first stator pole of the stator, a second joining section made of a second material on a second stator pole of the stator, wherein in a joined state of the first stator pole and the second stator pole, the first joining section overlaps with the second joining section in the circumferential direction of the stator in an overlap region, wherein the second joining section is further outward with respect to a center of the stator than the first joining section, wherein the second material is at least largely permeable to a predetermined laser wavelength, the first material is impermeable to the predetermined laser wavelength, and the first joining section is welded to the second joining section.

The variation possibilities and advantages described above in connection with the method according to the invention also apply analogously to the stator according to the invention. The corresponding method features can be seen as functional features in the stator.

In one embodiment, it is provided that the first stator pole has a joining section of the type of the first joining section on the outside on a side facing the second stator pole and a joining section of the type of the first joining section on the outside on an opposite side. It is also provided that the second stator pole has a joining section of the type of the second joining section on the outside on a side facing the first stator pole and a joining section of the type of the second joining section on the outside on an opposite side. This means that the first stator pole has a first joining section at each of its four corners in a radial plan view and is impermeable to the laser beam there. In contrast, the second stator pole has an external joining section at each of its four corners visible in a radial plan view. section made of a laser-transparent or laser-permeable material. This can be easily achieved by two different forms of overmolding of the stator poles, for example by completely overmolding the second stator pole with a laser-permeable plastic, so that on both sides and on the two overlapping areas in the circumferential direction (all four overlapping areas of a pole) the "outer overlap" (outer joining section) is always injected, and the first stator pole is completely overmolding with a laser-impermeable plastic, so that on both axial sides and on the two overlapping areas in the circumferential direction (all four overlapping areas of a pole) the "inner overlap" (inner joining section) is always injected. These very different stator poles must then be arranged alternately in the circumferential direction, so that an "outer overlap" (transparent) of the second stator pole can always overlap with the opaque "inner overlap" of the first stator pole and be welded. In this example there are two different types of stator poles.

In an alternative embodiment, the first stator pole has a joining section of the type of the first joining section on the outside on a side facing the second stator pole and a joining section of the type of the second joining section on the outside on an opposite side, and the second stator pole has a joining section of the type of the second joining section on the outside on a side facing the first stator pole and a joining section of the type of the first joining section on the outside on an opposite side. This in turn means that the two stator poles can be designed identically. In the radial plan view, for example, they each have an outer overlap on one side and an inner overlap on the other side. This therefore makes it possible to produce only one type of pole, which then has the outer overlap with the transparent material on one side (axial and/or circumferential direction) and the inner overlap with the opaque material on the other side. The pole would then be "asymmetrical" in the sense that two overlapping areas always have an outer overlap and two overlapping areas have an inner overlap. Geometrically correct, the pole would then be either axially symmetrical to the axial center plane, axially symmetrical to the center plane in the circumferential direction, or point-symmetrical to the center of the pole. When assembling the stator poles to form the stator ring, it is not the type of poles that needs to be taken into account, but rather the spatial orientation, so that the outer and inner overlap always come together. Such a stator pole would then have to be overmolded with two different materials, which can either be done in one step (using two or more injectors) or in several steps one after the other.

In a further embodiment, it is provided that the first stator pole has the first joining section on a side facing the second stator pole and, axially opposite, a joining section of the type of the second joining section and, on an opposite side in the circumferential direction opposite the first joining section, a joining section of the type of the second joining section axially outside and, axially opposite the latter, a joining section of the type of the first joining section and, and the second stator pole has the second joining section on a side facing the first stator pole and, axially opposite, a joining section of the type of the first joining section and, axially opposite the latter, a joining section of the type of the second joining section. In the radial plan view, this means that the inner overlap (type of the first joining section) and the outer overlap (type of the second joining section) alternate around the stator pole. As in the previous embodiment, both outer overlap and inner overlap are provided on a stator pole, but a single type of stator pole is sufficient to produce the stator ring. In the radial plan view, a pole would then be point-symmetrical to the center of the pole.

In an advantageous embodiment of the stator according to the invention, the joining sections are molded onto pole shoes and/or pole teeth of the respective stator poles. If necessary, the respective stator pole can be completely molded with the respective (insulating) material. The material therefore fulfills a multiple function, namely insulation and mechanical fixing of the stator poles to one another.

In a further embodiment, it is provided that one of the two joining sections in the overlapping area has a bead and the other of the two joining sections has a cavity, wherein in the joined state of the first stator pole and the second stator pole, the bead protrudes into the cavity. In particular, this can be used to lock the two stator poles to one another. In particular, this can be achieved by having overlapping areas on both axial sides of the stator poles each have such a bead and such a cavity and the respective beads in the locked state of the Stator poles protrude into the respective cavities. The beads and cavities can, for example, be round so that the stator poles can be releasably locked into one another. In principle, however, other geometric shapes of the beads and cavities can also be used. The beads and cavities do not have to extend over the entire radial length of the stator poles. If necessary, one or more short radial sections in which the respective beads and cavities protrude into one another are sufficient.

In a further advantageous embodiment of the stator according to the invention, it is provided that the joining sections welded together in the overlapping area along the entire radial extension of the stator poles seal a cooling circuit (inside the stator poles). For example, the spaces that arise between the stator poles or between their windings when they are joined together can be used for a coolant flow. A corresponding cooling circuit can be guided through all of the stator poles of the stator or just through a part of them. In order to seal this cooling circuit, the stator poles can be welded together along their entire radial extension (on both axial sides). Corresponding welds must then also be carried out on the radial end faces of the stator poles.

The joining sections can be positioned relative to one another in such a way that they press against one another when the first stator pole and the second stator pole are joined together. This pre-tension can be used in particular to ensure that the joining sections lie firmly against one another during welding. For this purpose, it is advantageous, for example, if the outer joining section (outer overlap) has an undercut so that it is designed to be springy. The inner joining section (inner overlap) can then be pressed into this undercut so that both joining sections press against one another when joined together.

In addition, it can be provided that a tolerance gap is formed in the circumferential direction between the first joining section and the second joining section. This can, for example, prevent manufacturing tolerances from preventing the joining sections from locking into one another precisely. This can create a stable, process-reliable (particularly with regard to tolerances) and media-tight connection between the poles or pole shoes.

In a further embodiment, the two stator poles each have a winding, and the joining sections are each arranged axially outside the windings. Optionally, the joining sections can be arranged exactly between the stator poles. Also optionally, the joining sections can protrude axially beyond the stator poles. For example, the overlapping areas can advantageously be arranged outside the coil areas or winding areas. They can also protrude slightly beyond the pole shoe and the pole (if necessary symmetrically between the outer overlap and the inner overlap), so that the connection point is also exactly between two poles. Optionally, however, this can also be designed asymmetrically, so that only the outer overlap protrudes beyond the pole and the inner overlap is still arranged in the pole area. Then the connection point is still in the pole area and not (in the middle) between the two poles.

The above-mentioned object is also achieved according to the invention by an electric axial flux machine with a stator of the type described above.

Further advantages, features and details of the invention emerge from the following description of preferred embodiments and from the drawing(s). The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and/or shown alone in the figures can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the invention.

• 1 einen Teil eines Stators einer Axialflussmaschine;
• 2 eine Schnittansicht des Stators von 1;
• 3 einen vergrößerten Ausschnitt von 2; und
• 4 einen vergrößerten Abschnitt von 3.

Showing:

• 1 a part of a stator of an axial flux machine;
• 2 a sectional view of the stator of 1 ;
• 3 an enlarged section of 2 ; and
• 4 an enlarged section of 3 .

The exemplary embodiments described in more detail below represent preferred embodiments of the present invention.

1 shows a section of a stator of an axial flux machine in perspective. The stator is formed by a ring-shaped arrangement of a large number of stator poles 1 joined together. The ring-shaped stator has a central axis 2, which not only forms the axis of rotation for one or more rotors (not shown), but also indicates the main magnetic flux direction. The following descriptions (but also the above explanations) with regard to radial directions, axial directions and circumferential directions always refer to this central axis 2.

Each stator pole 1 has pole shoes 3 on its axial sides. In the example shown, the pole shoes 3 are overmolded with a plastic 4, which can have holding and/or insulating functions. Each individual stator pole 1 was originally manufactured separately and overmolded with the plastic 4. The individual stator poles 1 were then assembled into the 1 The plastic overmoldings 4 of two stator poles 1 meet when the stator poles 1 are joined together and form an overlap region 5 which runs essentially in the radial direction.

Each stator pole 1 has a winding 6, which is arranged between the axially spaced respective pole shoes 3 on a respective pole tooth (not visible here).

2 shows a section through several stator poles 1 parallel to the central axis 2. The section shows the arrangement of a respective pole tooth 7 between the pole shoes 3 for each stator pole 1. Each pole tooth 7 is surrounded by a respective winding 6. A partial area of the section in which two windings 6 of two adjacent stator poles 1 meet and in which a part of the overlapping area 5 is also located is marked with III. This partial area III is in 3 shown enlarged. From this enlargement it can be seen that the pole tooth 7 can have an initial overmolding, which is also referred to here as (plastic) overmolding 4. A respective winding 6 is applied to this initial overmolding in the area of the pole tooth 7. Between the windings 6 of the two adjacent stator poles 1 there is a cooling chamber 8 which can be filled with a cooling medium.

In the example of 3 the stator pole shown at the bottom of the drawing can be referred to as the first stator pole 11 and the pole shown at the top of the drawing can be referred to as the second stator pole 12. The first stator pole 11 has a first joining section 21 on both axial sides. The first joining section 21 protrudes in the circumferential direction beyond the pole shoes 3. The first joining section 21 is preferably formed in one piece with the overmolding 41 of the pole tooth 7 of the first stator pole 11. In particular, the overmolding 41 and the first joining section 21 are made of the same (plastic) material.

In the same way, the second stator pole 12 has a second joining section 22 on both axial sides. This second joining section 22 also projects in the circumferential direction beyond the pole shoes 3 of the second stator pole 12.

In the 3 In the assembled state of the first stator pole 11 and the second stator pole 12 shown, the first joining section 21 and the second joining section 22 overlap in the overlap region 5. The second joining section 22 lies axially outside the respective first joining section 21 on both sides. Therefore, the first joining section 21 can be referred to as an inner overlap and the second joining section 22 as an outer overlap.

The first joining section 21 and the second joining section 22, i.e. the inner overlap and the outer overlap, are joined together by laser welding. For this purpose, the second joining section 22, which is on the outside, is made of a (largely) transparent material so that a laser beam 9 can penetrate the second joining section 22 and the essential energy of the laser beam 9 can reach the inner first joining section 21. This first joining section 21 melts and connects to the outer second joining section 22. This laser welding is carried out in the same way on the opposite axial side.

In 4 is the overlap area 5, which in 3 also designated IV, shown enlarged. The essential part of the overlapping area 5 is located between the circumferentially opposite pole shoes 3 of the two stator poles. In particular, a transparent or partially transparent section 221 of the second joining section 22 is located between circumferentially opposite pole shoe side surfaces 31 of the respective pole shoes 3. In the axial direction behind it (relative to the incidence of the laser beam) there is an opaque section 211 of the inner first joining section 21. Due to the 4 The opaque section 211 is melted in a contact region 10 by a laser beam (not shown) arriving from the left, which penetrates the transparent section 221. This results in a melting region which lies in the contact region 10. The first joining section 21 and the second joining section 22 are thus firmly connected by laser welding.

The joining sections 21 and 22 are designed on both opposite axial sides in such a way that they press against each other even before welding after the stator poles 11, 12 have been put together. This creates the contact pressure between the joining partners that is necessary for laser welding.

In the example of 4 the transparent section 221 is formed with a cavity 222 that is open towards the center of the stator pole, ie in the direction of the windings 6. In contrast, the opaque section 211 has a bead 212. In the example shown, both the cavity 222 and the bead 212 are round in cross-section. The contours of these two components can also be chosen differently, e.g. pointed. It is advantageous if the cavity 222 and the bead 212 are geometrically designed in such a way that they lock into one another when the two stator poles 11 and 12 are plugged together. This has the advantage that the stator ring is held together even before welding. In order to ensure the contact pressure just mentioned, the axial distance between the tips of the beads 212 in the non-joined state of the two stator poles 11 and 12 should be slightly larger than the distance between the deepest points of the cavities 222 of the axially opposite transparent sections 221.

During welding, the laser beam is guided, for example, in a radial direction over the entire radial extent of the overlap area 5. This welding creates a media-tight joint at least on the axial sides. The stator can be sealed in a suitable manner on the outer circumference (if necessary also by overlapping and laser welding) in order to obtain a media-tight cooling circuit.

List of reference symbols

1

Stator poles

2

central axis

3

Pole shoes

4

(Plastic) overmolding

5

Overlap area

6

Winding

7

Pole tooth

8th

Cavity or cold room

9

laser beam

10

Contact area

11

first stator pole

12

second stator pole

21

first joining section

22

second joining section

31

Pole shoe side surfaces

41

Overmolding with opaque material

42

Overmolding with transparent material

211

opaque section

212

bead

221

transparent section

222

cavity

III

Sub-area

IV

Sub-area

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed 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 accepts no liability for any errors or omissions.

Cited patent literature

• JP2011193564 [0004]
• WO 2011037087 [0004]
• US2008/0315699 [0005]
• EN 102016213110 [0005]
• JP2006325345 [0006]

Claims (15)

Method for producing at least part of a stator of an axial flow machine, characterized by - attaching a first joining section (21) made of a first material to a first stator pole (11) of the stator, - attaching a second joining section (22) made of a second material to a second stator pole (12) of the stator, wherein - in a joined state of the first stator pole (11) and the second stator pole (12), the first joining section (21) overlaps with the second joining section (22) in the circumferential direction of the stator in an overlap region (5), wherein - the second joining section (22) is located further outward with respect to a center of the stator than the first joining section (21), wherein - the second material is at least largely permeable to a predetermined laser wavelength, - the first material is opaque to the predetermined laser wavelength, and - irradiating the overlap region with laser radiation (9) of the predetermined Laser wavelength, whereby the first joining section (21) is welded to the second joining section (22). Procedure according to Claim 1 characterized in that the joining sections are welded in such a way that the overlapping region (5) seals off a cavity (8) between the two stator poles (11, 12) in a media-tight manner. Procedure according to Claim 1 or 2 characterized in that the stator has a central axis (2) which runs parallel to a respective main magnetic flux of the stator poles (11, 12), the second joining section (22) is arranged axially outside the first joining section (21) with respect to the central axis. Method according to one of the preceding claims, characterized in that the stator poles (11, 12) are each provided with a winding (6) before welding. Method according to one of the preceding claims, characterized in that the two stator poles (11, 12) are plugged together before welding, and the two joining sections (21, 22) snap into one another and/or form a positive connection. Stator for an axial flow machine characterized by - a first joining section (21) made of a first material on a first stator pole (11) of the stator, - a second joining section made of a second material on a second stator pole (12) of the stator, wherein - in a joined state of the first stator pole (11) and the second stator pole (12), the first joining section (21) overlaps with the second joining section (22) in the circumferential direction of the stator in an overlap region (5), wherein - the second joining section (22) is located further outward with respect to a center of the stator than the first joining section (21), wherein - the second material is at least largely permeable to a predetermined laser wavelength, - the first material is impermeable to the predetermined laser wavelength, and - the first joining section (21) is welded to the second joining section (22). Stator after Claim 6 , characterized in that - the first stator pole (11) has, on a side directed towards the second stator pole (12), a joining section of the type of the first joining section (21) axially on the outside and, on an opposite side, a joining section of the type of the first joining section (11) likewise axially on the outside and - the second stator pole (12) has, on a side directed towards the first stator pole (11), a joining section of the type of the second joining section (22) axially on the outside and, on an opposite side, a joining section of the type of the second joining section (22) likewise axially on the outside. Stator after Claim 6 , characterized in that - the first stator pole (11) has, on a side directed towards the second stator pole (12), a joining section of the type of the first joining section (21) axially on the outside and, on an opposite side, a joining section of the type of the second joining section (22) axially on the outside and - the second stator pole (12) has, on a side directed towards the first stator pole (11), a joining section of the type of the second joining section (22) axially on the outside and, on an opposite side, a joining section of the type of the first joining section (21) axially on the outside. Stator after Claim 6 , characterized in that - the first stator pole (11) has the first joining section on a side directed towards the second stator pole (12) and axially opposite a joining section of the type of the second joining section (22) and on an opposite side in the circumferential direction opposite the first joining section (21) axially outside a joining section of the type of the second joining section (22) and axially opposite the latter a joining section of the type of the first joining section (21) and - the second stator pole (12) has the second joining section (22) on a side facing the first stator pole (11) and, axially opposite, a joining section of the type of the first joining section (21) and, on an opposite side in the circumferential direction axially outside the second joining section (22), a joining section of the type of the first joining section (21) and, axially opposite the latter, a joining section of the type of the second joining section (22). Stator according to one of the Claims 6 until 9 characterized in that the joining sections (21, 22) are injection-molded onto pole shoes (3) and/or pole teeth (7) of the respective stator poles (11, 12). Stator according to one of the Claims 6 until 10 characterized in that one of the two joining sections (21, 22) in the overlap region (5) has a bead (212) and the other of the two joining sections has a cavity (222), wherein in the joined state of the first stator pole (11) and the second stator pole (12) the bead (212) protrudes into the cavity (222). Stator according to one of the Claims 6 until 11 characterized in that the joining sections (21, 22) welded together in the overlap region (5) along the entire radial extension of the stator poles (11, 12) seal a cooling circuit. Stator according to one of the Claims 6 until 12 characterized in that a tolerance gap is formed in the circumferential direction between the first joining section (21) and the second joining section (22). Stator according to one of the Claims 6 until 13 characterized in that the two stator poles (11, 12) each have a winding (6), and the joining sections (21, 22) are each arranged axially outside the windings (6). Electric axial flux machine with a stator according to one of the Claims 6 until 14 .

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