EP4029117A1

EP4029117A1 - Electrical machine having defined positioning of various recesses in a wet-running stator

Info

Publication number: EP4029117A1
Application number: EP20767965.5A
Authority: EP
Inventors: Michael Marsetz; Christian Ludwig
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2019-09-10
Filing date: 2020-08-26
Publication date: 2022-07-20
Also published as: CN114365388A; DE102019124256A1; US20220286002A1; WO2021047729A1

Abstract

The invention relates to an electrical machine (1) for driving a motor vehicle, comprising a housing (2), a stator (3), which is fixedly accommodated in the housing (2), and a rotor (4), which is mounted rotatably relative to the stator (3). The stator (3) has a laminated core (6) composed of a plurality of punched lamination segments (5a, 5b, 5c, 5d, 5d, 5e, 5f) and has a wire winding region (7) connected to the laminated core (6), and each lamination segment (5a, 5b, 5c, 5d, 5d, 5e, 5f) has, on its radial exterior (8), at least one radial recess (9a, 9b, 9c, 9d) also created by means of the punching production. A coolant guide channel (11) is delimited directly by an outer periphery (10) of the laminated core (6). A recess (9a) of a first lamination segment (5a) is spaced apart, along the outer periphery (10), from a recess (9b) of a second lamination segment (5b) directly abutting the first lamination segment (5a) in such a way that the recess (9a) of the first lamination segment (5a) is at least partly axially covered by an end face (12) of the second lamination segment (5b).

Description

Electrical machine with a specific positioning of various depressions on a wet-running stator

The invention relates to an electrical machine for driving a (purely electric or hybrid) motor vehicle, such as a car, truck, bus or other commercial vehicle, with a housing, a stator firmly held in the housing and a rotor mounted so as to be rotatable relative to the stator, wherein the stator has a laminated core composed of several sheet metal segments formed by stamping technology, as well as a wire winding area connected to the laminated core, and each sheet metal segment has at least one radial recess on its radial outer side which is also produced by the stamping process, and wherein a coolant duct directly through an outer circumference of the laminated core is bordered.

Generic electrical machines are already well known from the prior art. Reference is made to FIG. 13 for an exemplary embodiment of an electrical machine T according to the prior art. During the manufacture of the stator 3 'used in this electrical machine T, several notches are formed that run continuously in the longitudinal direction of the stator 3'. However, it has been found to be disadvantageous that these notches serve as a collecting channel for the coolant flowing over the outer circumference of the stator 3 ‘during operation and consequently redirect the coolant axially. This has the disadvantage that the areas of the stator lying radially within these notches are not or only insufficiently cooled.

It is therefore the object of the present invention to eliminate the disadvantages known from the prior art and, in particular, to improve the cooling of an electrical machine to increase the degree of effectiveness.

This is achieved according to the invention in that a recess of a first sheet metal segment along the outer circumference is in such a way relative to a recess of a, directly The second sheet metal segment resting against the first sheet metal segment is at a distance such that the recess of the first sheet metal segment is at least partially covered axially by an end face of the second sheet metal segment.

Such a distribution of the depressions in the different sheet metal segments makes it more difficult for the coolant flowing along the outer circumference during operation to flow axially. Thus, a larger part of the coolant reaches the areas of the stator that are below the recess. This increases the amount of heat dissipated and makes the electrical machine more efficient.

Further advantageous designs are claimed with the subclaims and explained in more detail below.

If the first sheet metal segment consists of a single sheet metal or several individual sheets stacked one on top of the other to form a partial package and / or if the second sheet metal segment consists of a single sheet metal or several individual sheets stacked one on top of the other to form a partial package, the assembly effort of the stator is further optimized.

It is also useful if the at least one individual sheet is formed from an electrical sheet. The at least one individual sheet preferably has a thickness of less than 1 mm.

In order to prevent the coolant from flowing axially even more effectively, it is also advantageous if there is a third sheet metal segment, also provided with a recess, which rests on an axial side of the first sheet metal segment facing away from the second sheet metal segment, the recess of the third sheet metal segment ent long the outer circumference is spaced relative to the recess of the first sheet metal segment in such a way that the recess of the first sheet metal segment is axially covered by an end face of the third sheet metal segment. In this context, too, it is advantageous if the third sheet metal segment consists of a single single sheet or several single sheets stacked one on top of the other to form a partial package.

Furthermore, it is expedient if the individual sheets of the different sheet metal segments are designed as identical parts, the at least one individual sheet of the first sheet metal segment being rotated relative to the at least one individual sheet of the second sheet metal segment. As a result, the manufacturing effort for the laminated core is kept as low as possible.

If each sheet metal segment is even equipped with several (preferably four) recesses arranged (unevenly) distributed along the circumference, each recess of the respective sheet metal segment being arranged along the circumference at a distance from the individual recesses of the directly adjacent sheet metal segment, who the different by the Stamping production conditional recesses are cleverly positioned in the circumferential direction relative to each other. This further improves the coolant distribution.

Furthermore, it is useful if several (axial) first through holes distributed along the circumference are introduced into the laminated core, the at least one recess of the first sheet metal segment having a greater distance along the outer circumference to the first through hole than the at least one recess of the second sheet metal segment. A plurality of depressions are thus preferably made in the respective individual sheet, of which at least two, more preferably three, of these depressions have different distances from the through holes closest to them. This results in a clever uneven distribution of the wells Ver along the outer circumference.

In this context, it is also advantageous if the at least one depression of the first sheet metal segment has a greater distance along the outer circumference to the through hole closest to it than the at least one depression of the third sheet metal segment. If there are more than three sheet metal segments, preferably five or six sheet metal segments, which more preferably each consist of a sub-package having several individual sheets, the stator can be implemented particularly efficiently.

Furthermore, it is advantageous for the distribution of the coolant if the recess of the respective sheet metal segment has a depth (radial extent) that measures less than 60%, more preferably less than 50%, of its width (extent along the outer circumference). As a result, the tendency to stick / the tendency of the coolant to accumulate within the respective depression is further reduced.

In other words, a positioning according to the invention of notches on wet-running stators is implemented to ensure cooling. In principle, two approaches are proposed to improve the oil distribution along the outer edge of the laminated core. One possibility is to avoid continuously longitudinal notches due to an uneven distribution of the notches (/ depressions) on the outer edge during the punching process of the sheet metal by twisting the sheet metal after the punching process during assembly to create isolated depressions instead of the longitudinal one to achieve running notches. By optimizing the position of these notches, the fluid guidance in the direction of the center of the outer circumference of the laminated core can be improved. Another approach is to make the notches flatter and wider in order to avoid an accumulation of coolant and the development of capillary forces in the notches.

The invention will now be explained in more detail below with reference to figures, in which context various exemplary embodiments are also shown.

Show it:

1 shows a perspective illustration of a region of an electrical machine according to the invention according to a first exemplary embodiment, in which an outer circumference of a stator can be clearly seen, FIG. 2 shows a perspective illustration of the electrical machine, similar to FIG.

1, with additional arrows to illustrate a direction of flow of the coolant conducted over the outer circumference during operation,

3 shows a perspective detailed illustration of the area marked with "III" in FIG. 2,

4 shows a front view of the electrical machine according to the invention,

FIG. 5 shows a detailed view of the area marked "V" in FIG. 4,

6 shows a side view of a circumferential region of a single sheet metal having a depression, as is shown in the embodiment shown in FIGS. 1 to 5 shown stator is inserted,

Fig. 7 is a perspective view of one of the FIGS. 1 to 5 inserted laminated core of the stator,

8 shows a perspective view of a laminated core used in an electrical machine according to a second exemplary embodiment, which is now equipped with four through holes instead of the three through holes present in the first exemplary embodiment,

Fig. 9 is a front view of a single sheet used to form the laminated core of the first Ausfüh approximately example,

10 is a perspective view of a laminated core of a stator designed according to a third exemplary embodiment, which differs from the first exemplary embodiment in terms of the distribution and arrangement of the depressions on the outer circumference of the laminated core.

11 shows a perspective illustration of the laminated core from FIG. 10, with arrows now additionally being shown to illustrate the direction of flow of the coolant guided along the outer circumference during operation, 12 shows a plan view of a section of a sheet metal blank with the individual sheet metal indicated on the part of its outer contour, as well as

13 shows a perspective illustration of an electrical machine according to the prior art.

The figures are only of a schematic nature and are used exclusively for understanding the invention. The same elements are provided with the same reference numerals. Furthermore, the various features of the different exemplary embodiments can in principle be freely combined with one another.

1, an electrical machine 1 according to the invention is illustrated in its basic construction. The ausgebil Dete with Fig. 1 according to a first embodiment electrical machine 1 is preferably used in its operation as a drive machine of a motor vehicle. The electrical machine 1 has a housing 2, which is shown in section in FIG. 1. In the housing 2, a stator 3 is attached permanently to the housing. A rotor 4 of the electrical machine 1 is in turn arranged radially within the annular stator 3. The rotor 4 is rotatably mounted relative to the stator 3 and further connected to a corresponding shaft of the motor vehicle in operation.

An axis of rotation of the rotor 4 is indicated in FIG. 1 with the reference number 17. The axially, radially and along a circumference / circumferential direction used here refer to this axis of rotation 17. Accordingly, the axial direction is a direction along the axis of rotation 17, a radial direction is a direction perpendicular to the axis of rotation 17 and a circumferential direction is a direction along a circular line running coaxially to the axis of rotation 17 or a circumferential line running around the axis of rotation 17.

As shown in more detail in FIG. 7, the stator 3 has a laminated core 6 as a base body. This laminated core 6 consists of several stacked one on top of the other, designed as equal parts individual sheets 13. In this embodiment, the individual sheets 13, which are each formed with a thickness of less than 1 mm, not to be known individually, but for the sake of simplicity combined to form sub-packages 14 Darge presents. In total, six sub-packages 14 are exemplified in this embodiment, with each sub-package 14 having several individual individual sheets 13 (preferably the same number of individual sheets 13) and as sheet metal segments 5a, 5b, 5c, 5d,

5e, 5f is designated below.

A single sheet 13 can also be seen in FIG. 9 by way of example. The individual sheet 13 has an annular extension. The individual sheet 13 has a plurality of radially extending slots 18 on its radially inner side, through which a plurality of wire windings of a wire winding region 7 run in the fully assembled state of the stator 3. Radially outside of the slots 18 there is an annular ring area 19 which is continuous in the circumferential direction. The ring area 19 is in turn provided on its radially outer side with a plurality of through holes 16a, 16b, 16c distributed in the circumferential direction. In the finally stacked state of the laminated core 6, the respective through holes 16a, 16b, 16c of the different individual sheets 13 are aligned in the axial direction in alignment with one another in order, as can also be seen in FIG. 4, via fastening means 20 (screws) to the housing 2 to be firmly connected.

In connection with FIG. 12, the specific shape of the respective individual sheet 13 is shown. In Fig. 12, a sheet metal blank 21 in the form of a sheet metal strip 22 / coil is to be known. The individual sheet 13 is punched out of this sheet metal strip 22, of which a radial outer contour / outer side 8 is drawn as a punched edge in FIG. 12. In a punching process, the individual sheet 13 is only largely punched out of the sheet metal strip 22 in a typical manner. At several points marked with the reference numeral 23, the individual sheet 13 is then still attached to the remaining sheet metal blank 21. Only then is the individual sheet 13 then completely separated out. In this Fleraustrennen arise in the individual sheet 13 corresponding recesses 9a, 9b, 9c, 9d in the form of notches / notches, which are arranged distributed in the circumferential direction Rich. In this context, it is pointed out that the points 23 in FIG. 12 to illustrate the general shaping process are drawn arbitrarily and not the distribution according to the invention, as it is then in more detail in connection with FIGS. 1 to 5 and 7 is shown corresponds.

Returning to FIG. 1, the wire winding area 7 is also shown schematically as an annular area. The wire winding area 7 stands on both axial sides of the laminated core 6 beyond this and is essentially connected radially within the annular area 19.

In FIG. 1, the various depressions 9a, 9b, 9c, 9d of the individual sheets 13 emerge from the common depressions 9a, 9b, 9c, 9d of a sheet metal segment 5a, 5b, 5c, 5d, 5e, 5f. The depressions 9a, 9b, 9c, 9d are distributed unevenly over the circumference on the respective sheet metal segment 5a, 5b, 5c, 5d, 5e, 5f. H. arranged at different angular distances in the circumferential direction with respect to the axis of rotation 17 distributed. This is also clear in FIG. 9: Accordingly, a first recess 9a is formed at a first distance a from the first through hole 16a closest to it along an outer circumference 10 of the laminated core 6. A second recess 9b is arranged at a second distance b from the second through hole 16b closest to it. A third recess 9c is positioned at a third distance c from the third through hole 16c closest to it. The fourth recess 9d is spaced apart by a fourth distance d from which it is closest to the first through hole 16a. In this embodiment, the first stand from a and the fourth distance d are chosen to be the same. The second distance b and the third distance c differ from one another and from the distances a and d.

While the individual sheets 13 of the same sheet metal segment 5a, 5b, 5c, 5d, 5e, 5f with their recesses 9a, 9b, 9c, 9d are each axially aligned with one another, the different sheet metal segments 5a, 5b, 5c, 5d, 5e, 5f arranged rotates relative to each other ver. This twisted arrangement leads, as can again be seen in FIG. 1, that a first recess 9a of a first sheet metal segment 5a is spaced in the circumferential direction / along the outer circumference 10 from the second recess 9b of the second sheet metal segment 5b and spaced from the recesses 9a, 9b , 9c,

9d of a third sheet metal segment 5c is arranged. So is the first indentation 9a of the first sheet metal segment 5a completed on both of its axial sides by a jewei end face 12, 15 of the second sheet metal segment 5b and the third sheet metal segment 5c. This results in an axially closed first recess 9a in the sense of a trough, as also in connection with FIGS. 2 and 3 easy to recognize. In this first recess 9a then collects a coolant which is conducted along the outer circumference 10 during operation and which does not run out directly from the bottom of the first recess 9a to the axial sides of the first recess 9a. This arrangement of the first recess 9a of the first sheet metal segment 5a also applies to the further recesses 9b, 9c, 9d. The depressions 9a, 9b, 9c, 9d of the further sheet metal segments 5b, 5c and 5d are also axially closed in this way. Only the sheet metal segments 5e and 5f arranged at the axial ends are open to one axial side. The coolant flows from the recesses 9a, 9b, 9c, 9d of the fifth and sixth sheet metal segments 5e and 5f onto the radial outside of the wire winding area 7.

With Fig. 5, a running through the housing 2 feed channel 24 of the Kühlmit tel directly on the laminated core 6 along conductive coolant duct 11 is illustrated ver. A coolant entering the interior from the outside of the housing 2 is guided directly along the laminated core 6 through the coolant duct 11 formed between the outer circumference 10 and the housing 2, so that the stator 3 is immediately wet-running / directly liquid-cooled.

In Fig. 6 a preferred shape of the respective recess 9a, 9b, 9c, 9d is shown. It becomes clear here that each recess 9a, 9b, 9c, 9d forms a flat / obtuse angle with its peripheral ramp surfaces 25a, 25b. In particular, each recess 9a, 9b, 9c, 9d has a depth (radial extent) that is less than half of a width, i. H. a circumferential extension, measures. As a result, excessive accumulation of coolant in operation in the recess 9a, 9b, 9c, 9d is avoided.

In FIGS. 8, 10 and 11 illustrate two further exemplary embodiments of the electrical machine 1 according to the invention. With these figures, for the sake of clarity, only the laminated cores 6 of the stator 3 are illustrated, the Further structure and the further functioning of the electrical machine 1 emerge from the first exemplary embodiment. For the sake of brevity, only the differences from the first exemplary embodiment are described below.

With the second embodiment of FIG. 8, a thicker laminated core 6 is realized. Eight sub-packages 14 are placed one on top of the other. As can be seen in this context, the individual depressions 9a, 9b, 9c, 9d of the sheet metal segments 5a to 5h are arranged in the axial direction along a zigzag line. Furthermore, four through holes 16a, 16b, 16c, 16d are provided in this embodiment.

In connection with FIGS. 10 and 11 it can also be seen that the distribution of the depressions 9a, 9b, 9c, 9d can be optimized in other ways. Accordingly, in this third exemplary embodiment, the depressions 9a, 9b, 9c, 9d closest to a common through hole 16a, 16b, 16c, 16 simulate an arrowhead contour.

In other words, according to the invention, the outer contour is designed in such a way that, despite the process-related notches in the individual sheets 13, a liquid cooling medium can flow off along the flanks from top to bottom. The notches 9a, 9b, 9c, 9d should therefore not deflect this cooling medium, so that the coolant leaves the flanks in the axial direction. Since notches, for example punching the sheet metal, are essential, they must be designed accordingly. However, the geometry of the notches can only be changed to a limited extent in terms of the depth and angle of the inlet. The advantage of the solution is the guarantee of cooling with a liquid medium without additional components, such as a cooling jacket, which keeps both the effort and the costs low. In the figures, the special notch geometry and arrangement in the stator laminated core 6 can be seen, which prevents the deflection of cooling liquid on the stator flanks. In terms of the inventive solution, both the geometry and the positioning of the notches and the joining process are defined in such a way that the cooling oil is not diverted axially to the outside and thus no longer contributes to the cooling of the flanks. In this case, a notch extending over the entire active length must be prevented. This must be taken into account in the design of the single sheet as well as in the joining process of the single sheets to the sheet stack. A deep and steep notch basically slows down an incoming liquid very strongly. In order to catch as little oil as possible, the notch must be designed as flat as possible. A tapering notch that is as wide and flat as possible prevents the incoming coolant from building up. In addition, the capillary effect and thus the axial deflection of the oil are weakened. An additional advantage of a shallow notch is the lower loss of strength that results in this area. However, a certain inflow and depth of the notch must be ensured due to the punching process. Therefore, the interception and the capillary effect cannot be prevented by the notch shape alone. Since an axial deflection cannot be prevented solely by the geometry of the notch, additional precautions must be taken to prevent the coolant from running off at the end faces. In order to prevent the liquid from running off to the side, the notch is interrupted over the active length in the laminated core. As a result of this arrangement, when the oil flows in, several drops form in the many depressions, which prevent lateral run-off due to the axial wall. The collection and drainage of the cooling liquid in the previous example is shown in FIGS. 2 and 3 can be seen. It can be seen here that due to the large number of interruptions in the notches, an axial drainage of liquid can only be expected in the outermost area. Most of the oil collects in the notches in the middle of the flank and continues to run as it accumulates. Overall, only a very small loss of coolant is to be expected on the flank. Furthermore, the part of the cooling oil running axially on the end faces can be used for additional cooling of the copper wire winding, which would otherwise have to be cooled in another way. In order to achieve such an arrangement of depressions in the stator lamination stack, the notches must be placed accordingly in the individual lamination. If the notch positions were evenly distributed over the outer contour, then completely solid notches would result when the individual sheets are stacked to form a package. The first step in solving this problem is to distribute the punched notches 9a, 9b, 9c, 9d unevenly. In order to obtain individual depressions in the laminated core instead of continuous notches, the sheets should be rotated relative to one another when stacking the individual sheets. In the example with three bores 16a, 16, 16c there is a three-fold rotation, that is to say by 120 ° in each case, with four bores (FIG. 8) there is a double rotation by 180 ° in each case possible. The stacking process during the joining process can be varied freely. For example, the lengths of the depressions can be varied by first forming smaller laminated stacks of the same orientation with the metal sheets, which are then joined together to form the overall package. In Fig. 3, six smaller stacks were formed and then rotated to each other ge added to the entire stator core. Furthermore, the concept can be optimized by defining a predetermined stacking sequence in order to optimize the coolant flow along the stator flank. In FIG. 10, the stacking sequence was defined in such a way that the depressions are oriented towards the center of the stator like an arrow. This ensures that the coolant that runs off is also increasingly distributed towards the center.

Reference list

1 electric machine

2 housings

3 stator

4 rotor

5a first sheet metal segment

5b second sheet metal segment

5c third sheet metal segment

5d fourth sheet metal segment

5e fifth sheet metal segment

5f sixth sheet metal segment

6 sheet metal package

7 wire winding area

8 outside

9a first recess

9b second recess

9c third recess

9d fourth recess

10 outer circumference

11 coolant duct

12 face of the second sheet metal segment

13 single sheet

14 partial package

15 Front side of the third sheet metal segment

16a first through hole

16b second through hole 16c third through hole

16d fourth through hole

17 axis of rotation

18 slot

19 ring area

20 fasteners 21 sheet metal blank

22 sheet metal strip

23 point

24 feed channel 25a first ramp surface

25b second ramp surface

Claims

1. Electrical machine (1) for driving a motor vehicle, with a Ge housing (2), a fixed in the housing (2) received stator (3) and a relative to the stator (3) rotatably mounted rotor (4), wherein the stator (3) has a laminated core (6) composed of several sheet metal segments (5a, 5b, 5c, 5d, 5e, 5f) formed by stamping technology, as well as a wire winding area (7) connected to the laminated core (6) and each of the sheet metal segments (5a, 5b, 5c, 5d, 5e, 5f) on its radial outer side (8) has at least one radial recess (9a, 9b, 9c, 9d) produced by the stamping production, and a coolant duct (11) directly through an outer circumference (10) of the laminated core (6) is limited, characterized in that a recess (9a) of a first sheet metal segment (5a) along the outer circumference (10) relative to a recess (9b) of a, directly on the first sheet metal segment (5a ) adjacent, two th sheet metal segment (5b) spaced et is that the recess (9a) of the first sheet metal segment (5a) is at least partially covered axially by an end face (12) of the second sheet metal segment (5b).

2. Electrical machine (1) according to claim 1, characterized in that the first sheet metal segment (5a) and / or the second sheet metal segment (5b) from a single single sheet (13) or several single sheets stacked one above the other to form a partial package (14) (13) exists.

3. Electrical machine (1) according to claim 1 or 2, characterized in that a third sheet metal segment (5c) also provided with a recess (9c) is present, which on one of the second sheet metal segment (5b) remote th axial side of the first sheet metal segment (5a), the recess (9c) of the third sheet metal segment (5c) along the outer circumference (10) so spaced relative to the recess (9a) of the first sheet metal segment (5a) that the recess (9a) of the first sheet metal segment an end face (15) of the third sheet metal segment (5c) is axially covered by (5a).

4. Electrical machine (1) according to claim 3, characterized in that the third sheet metal segment (5c) consists of a single single sheet (13) or several individual sheets (13) stacked one on top of the other to form a partial package (14).

5. Electrical machine (1) according to one of claims 1 to 4, characterized in that the individual sheets (13) of the sheet metal segments (5a, 5b, 5c, 5d, 5e, 5f) are designed as identical parts, the at least one single sheet (13) of the first sheet metal segment (5a) is rotated relative to the at least one individual sheet (13) of the second sheet metal segment (5b).

6. Electrical machine (1) according to one of claims 1 to 5, characterized in that each sheet metal segment (5a, 5b, 5c, 5d, 5e, 5f) with a plurality of recesses (9a, 9a, 9b, 9c, 9d), each recess (9a, 9b, 9c, 9d) of the respective sheet metal segment (5a, 5b, 5c, 5d, 5e, 5f) along the outer circumference (10) spaced from the individual recesses (9a, 9b, 9c, 9d) of the immediately adjacent sheet metal segment (5a, 5b, 5c, 5d, 5e, 5f) is arranged.

7. Electrical machine (1) according to one of claims 1 to 6, characterized in that a plurality of through holes (16a, 16b, 16c) distributed along the circumference are introduced into the laminated core (6), the at least one recess (9a) of the first sheet metal segment (5a) has a greater distance ent long from the outer circumference (10) to the first through hole (16a) than the at least one recess (9b) of the second sheet metal segment (5b).

8. Electrical machine (1) according to one of claims 2 to 7, characterized in that the at least one recess (9a) of the first sheet metal segment (5a) is a greater distance along the outer circumference (10) to the through hole (16a) closest to it. has than the at least one recess (9c) of the third sheet metal segment (5c).

9. Electrical machine (1) according to one of claims 1 to 6, characterized in that more than three sheet metal segments (5a, 5b, 5c, 5d, 5e, 5f) are present.

10. Electrical machine (1) according to one of claims 1 to 8, characterized in that the recess (9a, 9b, 9c, 9d) of the respective sheet metal segment (5a, 5b, 5c, 5d, 5e, 5f) has a depth that is less than 60% of its width.