WO2022156851A1

WO2022156851A1 - Segmented stator, method for producing a bath impregnated, segmented stator, and electric machine

Info

Publication number: WO2022156851A1
Application number: PCT/DE2022/100005
Authority: WO
Inventors: Stefanie ZELLER; Wolfgang Hill
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2021-01-25
Filing date: 2022-01-10
Publication date: 2022-07-28
Also published as: CN116802976A; DE102021101461A1

Abstract

The invention relates to a segmented stator (1) for an electric machine having an annular stator body (3) which is formed from a plurality of ring-segment-type stator segments (4), wherein a stator segment (4) has at least one stator tooth which protrudes radially inward or outward and is integrally formed with the stator segment (4) and around which is wound a stator winding (6), and the stator body (3) is enclosed, at least in portions, by an insulation (7), the insulation (7) having an axial end face (8) which has a slope (19) that extends from a radial outer edge (9) to a radial inner edge (10) or a slope that extends from the tangential stator segment centre to the tangential edges (17, 18) of the stator segment, or a combination of both slopes.

Description

Segmented stator, method for manufacturing a dip-impregnated segmented stator and electrical machine

The present invention relates to a segmented stator for an electrical machine with an annular stator body, which is formed from a plurality of annular segment-like stator segments, wherein a stator segment has at least one stator tooth which protrudes radially inwards and is formed in one piece with the stator segment and around which a stator winding is wrapped , and the stator body is at least partially surrounded by insulation. The invention also relates to a method for producing a dip-impregnated segmented stator and an electrical machine.

Segmented stators are basically already known from the prior art. DE19857954A1 describes such an electrical machine with a segmented stator, which has a plurality of stator segments overmoulded with plastic casings. These are arranged in a ring shape and are fastened to one another in the circumferential direction by way of tooth-tooth gap connections. A stator for an electrical machine is known from DE102008023923A1, which is composed of individual stator segments that are encapsulated with an insulating layer. Similar electrical machines are also described, for example, in EP1499000A1 and DE102008033601 A1.

The stator segments assembled to form a stator ring each have a stator tooth which carries a coil wound from a winding wire, with the winding wire having two open wire ends. In the case of segmented stators, these winding wires of the coils are connected to one another.

To insulate the stator, it is known to impregnate the stator completely or in sections. For this purpose, various impregnation methods are already known from the prior art. In the case of dip impregnation, for example, the entire stator is immersed or flooded and saturated in a flowable impregnation medium, such as resin. The resin is then cured by supplying energy. This can be done, for example, by energizing the stator coils, which heat up and thus cause the resin to gel. In particular, dip impregnation also enables the stator laminations to be fixed and the stator body and stator winding to be coated in a single process step. The dip impregnation also has the effect that the stator forms an overall system that is both electrically insulated and protected against abrasion.

Such a dip impregnation process from the prior art is described, for example, in EP2887507A1. After the impregnation medium has hardened, the insulated stator is then fixed in the motor housing, for example by means of a press fit.

Flooding is a procedural modification of dip impregnation. Here, a stator is first positioned in an empty impregnation basin, into which the free-flowing impregnation medium is subsequently let. For this purpose, after assembly, the stator can be flooded with impregnating resin in a stator support (housing part), with the housing part serving as a container for the resin. In terms of the process and the impregnation results, flooding is essentially equivalent to dip impregnation.

However, with the impregnation methods described above, it is possible that if the impregnating resin does not drain sufficiently from the stator, resin droplets and resin runs may form on the stator, which then interfere with the assembly or installation of the stator and lead to misalignments, for example.

In addition to the problems described above, due to the segmentation, the insulation system has a weak point at the junction of the segments, to which either clearances and creepage distances must be maintained (with the disadvantage of higher copper losses) or which are covered with insulating foils (with the disadvantage of high cost). The object of the invention is to provide a segmented stator for an electrical machine in which the risk of resin drops and resin runs being formed is reduced. It is also the object of the invention to implement reliable insulation with the highest slot filling factors at the lowest cost. It is also the object of the invention to implement an improved method for producing a dip-impregnated segmented stator. Finally, it is also the object of the invention to provide an electrical machine with an optimized stator.

This object is achieved by a segmented stator for an electrical machine with an annular stator body, which is formed from a plurality of annular segment-like stator segments, wherein a stator segment has at least one stator tooth which protrudes radially inwards and is formed in one piece with the stator segment and around which a stator winding is wrapped and the stator body is surrounded at least in sections by insulation, the insulation having an axial end face which in the yoke area has a gradient running from a radially outer edge to a radially inner edge or a gradient running from the tangential center of the stator segment to the tangential edge of the stator segments or a combination of both gradients.

Due to the slope of the insulating surface, the impregnating resin that has accumulated in the volume axially in front of the stator yoke flows off in a targeted manner in the area at the bottom of the slot where the joint forms the weak point of the core insulation. The flowing resin forms a safe layer of resin at the weak point over the course of the draining period and thus securely secures the insulation system.

This geometric adaptation of the insulation of a stator segment is intended to enable the impregnation material to flow off more easily and safely, on the one hand to avoid or at least reduce the formation of resin residues in the yoke area and, on the other hand, to use the impregnation material during the impregnation process specifically to protect the weak point of the insulation system by means of an even insulation layer guarantee. The insulation can be formed from any electrically insulating material, such as plastic, paper and/or ceramic.

The insulation can preferably be in the form of a plastic encapsulation of the stator body. Here, the stator segment can be inserted into an injection molding tool, for example, in order to be subsequently encapsulated in plastic, so that the plastic encapsulation is integrally and/or positively formed on the stator segment.

In principle, it is of course also conceivable to form an insulation as a separate component, in particular made of plastic, paper and/or ceramics, and then to connect it to the stator body in particular with a material and/or form fit.

It would also be conceivable for the insulation to consist of a composite material made of plastic, paper and/or ceramic. In this context, it is particularly preferred if the insulation is formed from a layered material comprising plastic, paper and/or ceramic.

In a preferred embodiment variant of the invention, it can be provided that the gradient is configured in such a way that a free-flowing, electrically insulating resin flows over the end face following the course of the gradient under the effect of gravity when the segmented stator is moved in the axial direction from an impregnation bath filled with the resin or the resin is discharged in the axial direction after flooding.

First, the individual elements of the claimed subject matter of the invention are explained in the order in which they are mentioned in the set of claims, and particularly preferred configurations of the subject matter of the invention are described below.

The segmented stator according to the invention is configured in particular for use in an electrical machine. The electrical machine is used to convert electrical energy into mechanical energy and/or vice versa, and it generally comprises a stationary part, referred to as the stator, stator or armature, and a part, referred to as the rotor or runner, which is arranged such that it can move, in particular rotate, relative to the stationary part.

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

For the purposes of this application, motor vehicles are land vehicles that are moved by machine power without being tied to railroad tracks. A motor vehicle can be selected, for example, from the group of passenger cars (cars), trucks (lorries), mopeds, light motor vehicles, motorcycles, buses (COM) or tractors.

The segmented stator is preferably intended for use in a radial flow machine. The stator of a radial flow machine is usually constructed cylindrically and generally consists of electrical laminations that are electrically insulated from one another and are constructed in layers and packaged to form laminated cores. This structure keeps the eddy currents in the stator caused by the stator field low.

A segmented stator body is characterized in that it is made up of individual stator segment parts. The stator body can be made up of individual stator teeth or stator tooth groups, with each individual stator tooth or each individual stator tooth group being formed from a large number of stacked, laminated electrical laminations, with each of the electrical laminations being designed as a stator segment sheet metal part. A laminated core or stator segment laminated part is understood to be a plurality of laminated individual laminations, which are generally produced from electrical sheet metal and are stacked and packaged one on top of the other to form a stack, the so-called laminated core. The individual laminations can then remain held together in the laminated core by gluing, welding or wedging or screwing or the like.

Stator teeth are components of the stator body which are designed as circumferentially spaced, tooth-like radially inwardly or outwardly directed parts of the stator body and between their free ends and a rotor body an air gap for the magnetic field is formed.

In particular, the stator can be arranged in a motor housing. The motor housing encloses the electric machine. A motor housing can also accommodate the control and power electronics. The motor housing can also be part of a cooling system for the electric machine and can be designed in such a way that cooling fluid can be supplied to the electric machine via the motor housing and/or the heat can be dissipated to the outside via the housing surfaces. In addition, the motor housing protects the electrical machine and any electronics that may be present from external influences. A motor housing can be formed in particular from a metallic material. Advantageously, the motor housing can be formed from a cast metal material, such as gray cast iron or cast steel. In principle, it is also conceivable to form the motor housing entirely or partially from a plastic.

According to an advantageous embodiment of the invention, it can be provided that a winding board extends in the axial direction, through which the ends of the stator winding are guided on the stator body, thereby providing a certain guidance and defined position for the ends of the stator winding. Furthermore, the winding board can also form a flow barrier or flow-guiding element for the flowable impregnation medium. According to a further preferred development of the invention, it can also be provided that the winding board has a feed-through opening for feeding through the ends of the stator winding, with a shoulder extending in the axial direction from the direction of the axial end face into the through-opening being arranged in the area of the feed-through opening, whereby a kind of dam is formed, which can prevent impregnating medium from flowing out through the lead-through opening.

Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the winding boards of two stator segments that are adjacent in the circumferential direction are configured in such a way that a gap is formed between the winding boards axially above a gap running in the axial direction (= insulation system weak point), whereby the outflow of the impregnation medium can be further optimized. According to a further particularly preferred embodiment of the invention, provision can be made for the gap to have a circumferential opening width of between 1 and 2.7 times the wire diameter. In this context, it is particularly preferable for the winding wire of the stator winding to have a circular cross section.

Furthermore, the invention can also be further developed in such a way that the axial end face of the insulation has a gradient running to a first peripheral edge and/or a second peripheral edge or a gradient running from the tangential center of the stator segment to the tangential edges of the stator segment or a combination of both gradients has, so that outflow of the impregnating medium can be further improved.

In order to provide optimized insulation, it can also be provided that the gap at the point of abutment of the stator segments is essentially completely filled with the electrically insulating resin. The object of the invention is also achieved by a method for producing a dip-impregnated segmented stator according to one of claims 1-8, comprising the following steps:

Assembly of a segmented stator according to one of Claims 1-8, dip impregnation of the segmented stator, comprising the steps of o immersing or flooding the segmented stator in its axial direction in an impregnation bath filled with a flowable impregnating medium, in particular a resin, o removing the segmented stator or draining it of the resin in its axial direction from the impregnation bath, o dripping off the impregnation medium from the segmented stator, and o thermosetting the impregnation medium.

According to the invention, a dip impregnation process is used, and the resin flow is designed in such a way that a larger volume of impregnation resin runs over the gap in the insulation system at the point of contact between two adjacent stator segments. A kind of varnish effect ensures that this weak point in the insulation system is covered with insulation.

Finally, the object of the invention is also achieved by an electrical machine, in particular for a hybrid or fully electric drive train of a motor vehicle, comprising a segmented stator according to one of Claims 1-8.

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

Figure 1 shows a segmented stator in a perspective view,

FIG. 2 shows a stator segment of a segmented stator in a perspective view, and

FIG. 3 shows a detailed view of two adjacent stator segments in a perspective view.

FIG. 1 shows a segmented stator 1 for an electrical machine with an annular stator body 3, which is formed from a plurality of stator segments 4 in the shape of annular segments. The directional information used is indicated by the arrows denoting the axial direction 21 , the radial direction 22 and the circumferential direction 23 . This is explained in more detail below with reference to the detailed view of FIG.

FIG. 2 shows a stator segment 4 with a stator tooth core which protrudes radially inwards and is formed in one piece with the stator segment 4, which has insulation 7 and has a stator winding 6 wrapped around it. The stator tooth core is therefore covered by the stator winding 6 in the illustration in FIG. 2 and is only visible in the yoke area. The stator winding 6 is wound around the stator tooth core in the axial direction 21 and the circumferential direction 23 .

The stator tooth core of the stator segment 4 is surrounded at least in sections by a plastic extrusion coating 7 on its tangentially and axially outer circumference. The insulation 7 embodied as a plastic extrusion coating has an axial end face 8 which has a gradient 19 running from a radially outer edge 9 to a radially inner edge 10 . The slope 19 is configured such that a flowable electrically insulating resin flows by gravity over the face 8 following the slope of the slope when the segmented stator 1 is moved axially from an impregnation bath filled with the resin. This is indicated by the dashed arrow numbered 19 implied. Furthermore, the end face 8 also has a slope in the circumferential direction 23 , which slopes down from the tangential center of the stator segment to the edges 17 and 18 .

It can also be seen from FIG. 2 that a winding board 12 extends in the axial direction 21, through which the ends 11 of the stator winding 6 on the stator body 3 are guided. The winding board 12 has a feed-through opening 13 for feeding through the ends 11 of the stator winding 6 .

A gradient 19 is therefore provided on the plastic extrusion coating 7 of a stator segment 4 in the radially outer yoke area, whereby a free-flowing resin flows radially inward to the winding board 12 when the segmented stator 1 is moved out of a corresponding impregnation bath in the axial direction or the resin in the axial direction direction is released. The winding boards 12 have the task of supporting the winding head during the winding process and at the same time preventing the resin from flowing further and thereby guiding it to the gap 15 .

As shown in FIG. 3, the winding boards 12 of two circumferentially adjacent stator segments 4 are configured such that a gap is formed between the winding boards 12 that runs radially in the end face and then in the groove bottom in the axial direction. The axial end face 8 of the plastic encapsulation 7 also has a slope 20 running to a first peripheral edge 17 and/or a second peripheral edge 18 . The direction of the gradient is indicated by the dashed arrow with the reference number 20 . The gradient 20 is also configured so that a flowable electrically insulating resin flows by gravity following the gradient of the gradient over the face 8 to the gap 15 when the segmented stator 1 is moved axially from an impregnation bath filled with the resin or the resin is drained after flooding becomes. A further advantage of this design is that the gap at the point of contact between the adjacent stator segments 4 is closed by the resin flowing out, which avoids the need to maintain air and creepage distances from the coil to the iron core in the middle of the slot base in tight installation spaces.

The following procedure can be used to produce a dip-impregnated segmented stator 1, as shown in FIGS. 1-2: o assembly of a segmented stator (1), o dip-impregnation of the segmented stator (1), comprising the steps

Immersing or flooding the segmented stator (1) in its axial direction in an impregnation bath filled with a free-flowing impregnation medium, in particular a resin,

removing the segmented stator (1) in its axial direction from the impregnation bath or draining the insulating resin in the axial direction,

Draining the impregnating medium from the segmented stator (1) and thermosetting the impregnating medium.

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

I stator

3 stator body

4 stator segment

6 stator winding

7 insulation

8 face

9 edge

10 edge

II ends

12 winding board

13 grommet opening

14 paragraph

15 gap

16 opening width

17 edge

18 fringe

19 drops

20 drops

21 axial direction

22 radial direction

23 circumferential direction

Claims

Claims Segmented stator (1) for an electrical machine with an annular stator body (3), which is formed from a plurality of annular segment-like stator segments (4), wherein a stator segment (4) has at least one radially inwardly or outwardly projecting and connected to the stator segment ( 4) has a one-piece stator tooth around which a stator winding (6) is wrapped, and the stator body (3) is surrounded at least in sections by insulation (7), characterized in that the insulation (7) has an axial end face (8). which has a gradient (19) running from a radially outer edge (9) to a radially inner edge (10) or a gradient running from the tangential center of the stator segment to the tangential edges (17, 18) of the stator segment, or a combination of both gradients . Segmented stator (1) according to claim 1, characterized in that a winding board (12) extends in the axial direction, through which the ends (11) of the stator winding (6) on the stator body

(3) are guided. Segmented stator (1) according to one of the preceding claims, characterized in that the winding board (12) has a feed-through opening (13) for leading through the ends (11) of the stator winding (6), wherein in the area of the feed-through opening (13) a A shoulder (14) extending in the axial direction from the direction of the axial end face (8) into the passage opening (13) is arranged.

4. Segmented stator (1) according to one of the preceding claims, characterized in that the winding boards (12) of two stator segments (4) that are adjacent in the circumferential direction are configured in such a way that there is a gap (15 ) is trained.

5. Segmented stator (1) according to claim 4, characterized in that the gap (15) has a circumferential opening width (16) between 1-2.7 times the wire diameter.

6. Segmented stator (1) according to one of the preceding claims, characterized in that the gap (15) is arranged axially above a gap running in the axial direction at the joint between adjacent stator segments (4) and an insulating layer over and from the running impregnation medium / or is formed in the gap.

7. Segmented stator (1) according to one of the preceding claims, characterized in that the gradient (19,20) is configured in such a way that a flowable, electrically insulating resin causes gravity to follow the gradient over the end face (8) to the gap (15) flows when the segmented stator (1) is moved in the axial direction from an impregnation bath filled with the resin. - 15 - Segmented stator (1) according to one of the preceding claims, characterized in that the gap at the joint between adjacent stator segments (4) is substantially completely filled with the electrically insulating resin. A method for producing a dip-impregnated segmented stator (1) according to any one of the preceding claims 1-8, comprising the following steps: o assembling a segmented stator (1) according to any one of claims 1-8, o dip-impregnating the segmented stator (1), comprehensive the steps

Draining the impregnation medium or removing the segmented stator (1) in its axial direction from the impregnation bath,

Draining of the impregnation medium from the segmented stator (1) and

heat curing of the impregnation medium. Electrical machine, in particular for a hybrid or all-electric drive train of a motor vehicle, comprising a segmented stator according to one of Claims 1-8.