WO2021165519A1

WO2021165519A1 - Winding a production method for same

Info

Publication number: WO2021165519A1
Application number: PCT/EP2021/054249
Authority: WO
Inventors: Steffen Riepert
Original assignee: Elringklinger Ag
Priority date: 2020-02-20
Filing date: 2021-02-20
Publication date: 2021-08-26
Also published as: DE102020104508A1

Abstract

The invention relates to a winding of an electric motor. According to the invention, in order to create a more efficient production method and an improved hairpin winding, all hairpins (2) of the hairpin winding to be produced are fixed in an arrangement for subsequent introduction into grooves (4) of a laminated core of a stator (3), and this arrangement of hairpins (2) is provided with an insulation made of a plastic (5) in an injection moulding method, wherein the individual hairpins (2) are connected as one piece up to their free end regions with contact feet (7) via a winding head (8, 12) surrounded by the plastic (5) to form a crown-shaped component (1). In a further development of the invention, the winding head (8, 12) forms part of a cooling system of the winding head (8, 12).

Description

Winding and manufacturing process therefor

The present invention relates to a winding of an electric motor and a manufacturing method for such a winding.

It is known from the prior art that a winding of an electric motor is introduced into a laminated core which has grooves for receiving it. It is also known that when winding stators for electric motors, the highest possible copper fill factor in the stator slots is achieved by using so-called hairpin or hairpin windings instead of conventional winding technologies using one-piece round wire can be used. Hair pin windings, used here as a synonym for all windings composed of sections, are made using flat wire instead of round wire and achieve a fill factor of approx. 60%. Conventional hairpin windings consist of a solid profile wire made of copper with a rectangular cross-sectional profile, which is inserted into the slots of the stator in the form of individual hairpins or as a correspondingly ordered package of numerous aligned hairpins. In the following, the production of a winding on a stator of an electric motor is primarily discussed, since a winding on a stator is in principle larger than a winding of a rotor and therefore negative effects also occur here to a greater extent.

In the manufacture of a hairpin winding, a very complex insulation process results in particular disadvantages, which result from long process times, manufacturing and machine costs as well as additional material costs: first you have to a slot insulation can be folded and shot into the respective slots, see e.g. US 2017/0302143 Al. This is followed by a predetermined arrangement of the hairpins, an insertion of this arrangement into the slots of the stator, an insertion of so-called cover slides to close the slots, a bending of the hairpin ends in the switching position and the interconnection of the individual hairpins to form a winding of a zone plan, a very time-intensive impregnation process with the sub-steps

- heating of the stator;

- Introducing an impregnation compound by soaking, dipping, trickling or similar methods for introducing an impregnation compound at least in the area of the slots of the stator;

- The impregnation compound gels and / or excess impregnation compound drips off and finally

- Baking the impregnation compound, the sub-steps mentioned taking place under comparatively poor process monitoring. According to the prior art, however, it is necessary that a stator is impregnated in order to ensure strength and positioning of the winding in the slots of the stator with improved thermal connection to the stator and, at the same time, electrical insulation from the metallic stator.

The present invention has the object of creating a more efficient manufacturing method and also an improved hairpin winding.

According to the invention, this object is achieved by the features of claim 1. Accordingly, in a method according to the invention, all hairpins of a hairpin winding to be produced in each case are fixed in an arrangement for subsequent introduction into slots of the laminated core of the stator and in this arrangement in an injection molding process with insulation provided with a plastic, through which the individual hairpins are integrally connected to their free end areas with contact feet via a winding head enclosed by the plastic to form a crown-like component. Compared to the impregnation method described above, an injection molding method has an optimized process monitoring and is also significantly faster to manufacture than any known impregnation of the hairpins, which according to the prior art still requires insulation in the slots of the stator that has to be separately produced beforehand is to be supplemented.

A device according to the invention therefore provides as a solution to the above-mentioned object that a hairpin winding that can be inserted into a grooved laminated core, in particular a stator, has an insulation that is implemented as a one-piece injection-molded part made of plastic, the injection-molded part in all areas the hairpins, which are arranged for insertion ben in corresponding grooves of the stator, except for their end areas with contact feet and the hairpins are connected to a component in the area of a winding head by the injection molded part. All areas of the essentially U-shaped hairpins are insulated by plastic except for the contact feet from their end areas and are connected to one another in the area of a winding head to form a component. This means that the hairpins themselves have an electrically insulating impregnation through the plastic, and the slots in the stator no longer have any insulation otherwise usually formed by paper sleeves.

Advantageous further developments of the invention are the subject of the dependent claims. Accordingly, after the plastic-coated hairpins have been inserted into the corresponding grooves of the stator, the contact feet of the hairpins are used to form a Interconnection bent as a predetermined winding and welded ver. Subsequently, an area around the electrically connected contact feet with the stator is inserted into an injection molding tool and injected with an insulation made of a plastic to form a further winding or winding head.

In a particularly advantageous embodiment of the invention, in the step of an injection molding process, grooves are formed on a winding head enclosed with plastic. These grooves are used in an installed position of the end winding as a means for forming a cooling device. Thus, in one embodiment of the invention in the area of the encapsulated winding head interconnected grooves are formed as cooling channels and ra dial closed grooves for the subsequent reception of you lines. For example, on a hairpin winding in the injection-molded insulation of the respective winding head, means are provided for active cooling of the electrically insulating overmolded winding head during normal operation to dissipate electrical power loss, as already implemented on the stator itself according to the state of the art is. An essential finding of the present invention is that the winding heads were recognized as thermal hotspots in an electric motor, even with hairpin windings. Cooling of a winding head that has hitherto been used at least for hairpin windings and which has so far only been based on convection and / or heat radiation leads to a large spread between peak and continuous power of the electric motor due to the electrical losses that occur here. Active cooling, now also provided in the area of the winding head, by means of channels, on the other hand, reduces this spread between peak and continuous power and, with a compact design, also reduces the losses in the winding head. This embodiment of the invention thus only represents an extension of what is generally already existing cooling circuit, which now means a little additional effort be over the area of the Nu th of the stator.

In a further development of a manufacturing method, hairpins, which are fixed in an arrangement for introduction into the stator, are overmolded in an injection molding tool to form a so-called "stator crown" with an insulating plastic so that this stator crown is an overall component in the stator one can be pushed, as has so far only been carried out according to the prior art with a correspondingly arranged package of hairpins, which consists of numerous aligned but loosely held individual hairpins Prepare that each prong or foot of the stator crown has a locking lug for automatic fixation and / or a wave or fir tree profile for positioning on the stator package The locking lug formed by the plastic of the encapsulation is provided Prechende latching of the prongs emerging freely from the grooves of the stator is used, so that no modifications within the grooves of the stator are required here. Accordingly, latches provided on plastic encapsulation of the hairpins are formed in an installation position for latching on the overmolded end winding opposite the end of the slots of the stator. In such an arrangement, the following known work steps follow, in which the protruding ends of the HairPins free of any electrical insulation are brought into a predetermined position by targeted twisting and welded in pairs at their ends, as known from the prior art . The described locking lugs on the prongs act in these steps through the automatic fixation of the Unlocked stator crown effectively counteracts any displacement with respect to the stator or within the slots of the stator.

The end winding of the stator crown advantageously has cooling channels which are provided with two delimiting O-ring grooves. O-rings fixedly inserted in the O-ring grooves seal the end winding in use or in an installation position of the stator with the end windings from a motor housing.

According to an advantageous development, at least one cooling channel is provided between the O-ring seals, which is designed as a spiral or helix between the O-ring seals. This cooling duct is connected to a motor cooling system in order to remove the electrical losses in the form of heat in a later installation position of the stator.

According to a particularly advantageous development of the inven tion, a stator prepared in the manner described above by interlocking insertion of a stator crown with interconnected contact feet is finally inserted into an injection molding tool and an area of the interconnected contact feet is used to form a second winding head with a Plastic encapsulated, with the stator itself then also being coated with an electrically insulating plastic layer. In a particularly preferred embodiment of the invention, this overmolding also takes place with the formation of grooves for seals and recesses for cooling channels, as described above for the formation of the “stator crown”. A hairpin winding closed in a stator now has two end windings each of which has a cooling system for discharging electrical losses. The invention has been shown above based only on U-shaped curved hairpins in a stator. In principle, however, the invention can be adapted to all conceivable pin windings, that is to say in particular I-pins. Likewise, in addition to stator windings and rotor windings, adapting the invention can be designed accordingly, since grooved laminated cores are used here as well.

Further features and advantages of embodiments according to the invention are explained in more detail below with reference to an embodiment example with reference to the drawing. Show in it:

FIG. 1: a three-dimensional view of a stator crown formed by injection molding with an arrangement of individual hairpins fixed therein;

FIG. 2: a three-dimensional view of an embodiment of a stator manufactured using a stator crown from FIG. 1;

FIG. 3: a section through the embodiment of the completed stator from FIG. 2, indicating an internal structure with interconnection in the area of the end windings and

Figures 4a and 4b:

Enlargements of detail A and B from FIG. 3.

The same reference symbols are always used for the same elements or method steps across the various figures and exemplary embodiments. FIG. 1 shows a three-dimensional view of a stator crown 1 formed by injection molding with a plastic with an arrangement of individual hairpins 2 fixed therein Inserted into grooves 4 of the stator 3 here only one Blechpa ket comprehensive fixed aligned. This arrangement of hairpins 2 was provided with insulation made of plastic 5 in an injection molding process. The individual hairpins 2 are known to be U-shaped and are insulated with the plastic up to free end regions 6 with contact feet 7, the hairpins 2 being connected in one piece to the stator crown 1 via a winding head 8 enclosed by the plastic 5 . This stator crown 1 is then inserted into a stator 3 in the direction of the arrow P in FIG. 1 in such a way that the slots 4 of the stator 3 are filled and the end winding 8 is flush with the stator 3.

The stator crown 1 has in the area of the winding head 8 enclosed by the plastic 5 not only the electrical connections 9 of the winding from the individual hairpins 2 yet to be finished, but also different types of grooves 10, in a later installation position as a means for Formation of a cooling device are formed. For this purpose, radially closed grooves are also provided, which have already been provided with seals 11 in the illustration in FIG intended.

FIG. 2 shows a three-dimensional view of an embodiment of a stator 3 with completed winding using the stator crown 1 from FIG. This winding lies inside the stator 3 shown, which forms a hollow cylinder with a closed outer jacket for the latest on acquisition of a rotor.

FIG. 3 is a section through the embodiment of the completed stator from FIG. 2 along a central axis, indicating an internal structure with interconnection of the hairpins 2. After the crown-like component 1 from FIG to form a corresponding interconnection of the hairpins 2 contained therein were bent and welded. In order to prevent displacement of the stator crown 1 during these processes, latches made of the plastic 5 are provided near the free end region 6 of the hairpins 2, which are described below with the aid of enlarged sections of FIGS. 4a and 4b.

At the completion of the winding in the stator 3 a loading was rich around the now electrically connected contact feet 7 with egg nem adjacent part of the stator 3 in an injection molding tool and injected to form another end winding 12 with a supplementary insulation from the plastic 5 to . Also in this end winding 12 grooves 10 are again vorgese hen to form channels of cooling in an insert, which in turn seal via seals 11 with respect to a cylindrical outer housing, not shown.

The illustrations in FIGS. 4 a and 4 b show, in enlarged sections A and B of FIG. FIG. 4 a shows a spring-elastic locking lug 13 which, when the stator crown 1 reaches an end position, automatically engages in recesses 14 of the stator 3 when it is pushed into the grooves 4 of the stator 3. In contrast to this, in the exemplary embodiment of FIG. 4b, no recesses 14 are required in the area of the stator 3. The locking lugs 13 are arranged on the free end regions 6 near the contact feet 7 so that the locking lug 13 engages behind the stator 3 with reaching an end position of the stator crown 1 and only protrudes minimally from the grooves 4 of the stator 3.

With the technology described above, it is advantageously possible to replace numerous time-consuming and material-consuming steps for the preparatory isolation of HairPins from the slots of the stator by inserting a stator crown as a half-finished winding. In addition to electrical insulation, advantageous new means for improving cooling of the end windings are also provided as further relevant parts of the stator winding in use.

LIST OF REFERENCE NUMERALS stator crown / crown-like component hairpin stator or stator laminated core of an electric motor slot of the laminated core of the stator 3 plastic as electrical insulation free end area of the hairpins 2 contact foot encapsulated winding head, enclosed by the plastic 5 electrical connection of the winding of the stator 3 0 slot for Cooling circuit in the extrusion coating of the end winding 8 1 groove with seal 2 end winding 3 resilient locking lug 4 recess in the area of a groove 4 of the stator 3

P direction of insertion when inserting the crown-like component 1 into the stator 3

Claims

Expectations

1. A method for producing a hairpin winding of an electric motor, in which hairpins (2) are arranged in a predetermined manner for joint insertion into grooves (4) of a laminated core, characterized in that all hairpins (2) of the hairpin winding to be produced are in one Arrangement for the subsequent introduction into grooves (4) of the laminated core of a stator (3) are fixed, and this arrangement of hairpins (2) is provided with a plastic insulation in an injection molding process, the individual hairpins (2) up to their free end areas (6) with contact feet (7) are connected in one piece to a crown-like component (1) via a winding head (8) enclosed by the plastic.

2. The method according to the preceding claim, characterized in that after the insertion of the crown-like component (1) into corresponding grooves (4) of the stator (3), the contact feet (7) are bent and welded to form an interconnection and an area placed around the electrically connected contact feet (7) with the stator (3) in an injection molding tool and encapsulated with a plastic insulation to form a further end winding (12).

3. The method according to any one of the preceding claims, characterized in that in the step of an injection molding process grooves (10) are formed on a winding head (8, 12) enclosed with plastic.

4. The method according to the preceding claim, characterized in that the grooves (10) are used in an installation position of the stator (3) as a means for forming a cooling device on the end winding (8, 12).

5. The method according to any one of the preceding claims, characterized in that on a winding head (8, 12) radially closed grooves (10) for the subsequent arrangement of seals (11) are used.

6. The method according to any one of the preceding claims, characterized in that a stator (3) with interconnected contact feet (7), which has been prepared by locking a stator crown (1), is finally inserted into an injection molding tool, a region of the interconnected contact feet ( 7) is encapsulated with a plastic (5) to form a two-th winding head (12).

7. Hairpin winding of an electric motor which has been produced according to one of the preceding claims, characterized in that the hairpin winding which can be used in grooves (4) of a laminated core of a stator (3) has an insulation which is made as a one-piece injection molding -Part is made of a plastic, the injection-molded part all areas of the hairpins (2) that are arranged for insertion into the grooves (4) of the stator (3), with the exception of their end areas (6) with contact feet ( 7) and the hairpins (2) in the area of a winding head (8) through which the injection-molded part are connected to form a component.

8. Hairpin winding according to the preceding claim, characterized in that in the region of the overmolded winding head (8, 12) interconnected grooves (10) are designed as cooling channels and radially closed grooves for receiving seals (11).

9. Hairpin winding according to one of the two preceding claims, characterized in that on plastic injections of the hairpins (2) locking lugs (13) are provided, which in an installed position for locking in recesses (14) of the grooves (4 ) of the stator (3) or on one of the ends of the grooves (4) of the stator (3) opposite the overmolded winding head (8).

10. Hairpin winding according to one of the three preceding claims, characterized in that a winding head (8, 12) has cooling channels in the form of grooves (10) which are provided with two delimiting grooves which are designed to receive seals are, so that these seals, in particular in the form of O-rings inserted into grooves, seal the end winding (8, 12) in an installation position of the stator (3) from a motor housing.