Electric machine with various recesses definedly positioned in a wet-running stator

Abstract

The invention relates to an electric motor (1) for driving a motor vehicle, the electric motor comprising a housing (2), a stator (3) and a rotor (4), the stator being fixedly received in the housing (2) and the rotor being rotatably mounted relative to the stator (3). The stator (3) has a laminated core (6) comprising a plurality of stamped laminated segments (5a, 5b, 5c, 5d, 5d, 5e, 5f) and a conductor winding region (7) connected to the laminated core (6), and each laminated segment (5a, 5b, 5c, 5d, 5d, 5e, 5f) also has at least one radial recess (9a, 9b, 9c, 9d) produced by stamping on the radially outer portion (8) of the laminated segment. A coolant guide channel (11) is directly delimited by the outer periphery (10) of the laminated core (6). The recess (9a) of the first lamination segment (5a) is spaced apart from the recess (9b) of the second lamination segment (5b) directly adjacent to the first lamination segment (5a) along the outer periphery (10), so that the recess (9a) of the first lamination segment (5a) is at least partially axially covered by the end face (12) of the second lamination segment (5b).

Description

Technical Field

[0001] The invention relates to an electric machine for driving a (purely electric or hybrid) motor vehicle, such as a car, truck, bus or other commercial vehicle, the electric machine comprising a housing, a stator and a rotor, the stator being received in a fixed manner in the housing and the rotor being mounted rotatably relative to the stator, wherein the stator has a laminated core comprising a plurality of stamped laminated segments and has a conductor winding region connected to the laminated core, and each laminated segment also has on its radial outer portion at least one radial recess produced by means of stamping, and wherein a coolant-conducting channel is directly delimited by the outer circumference of the laminated core. Background Art

[0002] Electric machines of this type are already sufficiently known from the prior art. For an exemplary embodiment of an electric machine 1 ' according to the prior art, reference is made to FIG. 13 . During the manufacture of a stator 3 ' for this electric machine 1 ', several recesses extending continuously in the longitudinal direction of the stator 3 ' are formed. However, it has been found to be disadvantageous that these recesses act as collecting channels for the coolant flowing through the outer periphery of the stator 3 ' during operation and thus divert the coolant axially. This has the disadvantage that the regions of the stator which are radially inside these recesses are not cooled at all or are only cooled inadequately. Summary of the invention

[0003] It is therefore an object of the present invention to remedy the disadvantages known from the prior art and in particular to improve the cooling system of an electric machine in order to increase the efficiency.

[0004] According to the invention, this is achieved in that the recess of the first laminate segment is spaced apart along the outer circumference relative to the recess of the second laminate segment directly adjacent to the first laminate segment, so that the recess of the first laminate segment is at least partially axially covered by the end face of the second laminate segment.

[0005] This distribution of the recesses of the different lamination sections makes it more difficult for the coolant flowing along the outer periphery to escape axially during operation. As a result, a larger portion of the coolant reaches the area of ​​the stator located below the recesses. This increases the heat dissipation and helps to improve the performance of the electric machine.

[0006] Further advantageous embodiments are claimed by the dependent claims and are explained in more detail below.

[0007] The assembly effort of the stator is further optimized if the first lamination section comprises a single individual lamination or several individual laminations stacked one above the other to form a substack and / or if the second lamination section comprises a single individual lamination or several individual laminations stacked one above the other to form a substack.

[0008] It is also advantageous if at least one individual laminate is formed by an electrical sheet. The at least one individual laminate preferably has a thickness of less than 1 mm.

[0009] In order to more effectively prevent the coolant from flowing out axially, it is advantageous if there is a third lamination section which is also provided with a recess: the third lamination section is adjacent to the axial side of the first lamination section which faces away from the second lamination section, wherein the recess of the third lamination section is spaced apart from the recess of the first lamination section along the outer circumference so that the recess of the first lamination section is axially covered by the end face of the third lamination section.

[0010] In this case, it is also advantageous if the third lamination section comprises a single individual lamination or a plurality of individual laminations which are stacked on top of each other to form a sub-stack.

[0011] Furthermore, it is advantageous if the individual laminations of different lamination sections are designed as identical components, wherein at least one individual lamination of a first lamination section is rotated relative to at least one individual lamination of a second lamination section. This keeps the manufacturing effort of the lamination core as low as possible.

[0012] If each lamination segment is even provided with several (preferably four) recesses arranged in (non-uniform) distribution in the circumferential direction, wherein each recess of the respective lamination segment is arranged in the circumferential direction spaced apart from the individual recess of the immediately adjacent lamination segment, the different recesses produced by stamping are positioned neatly relative to one another in the circumferential direction. This further improves the distribution of the coolant.

[0013] Furthermore, it is useful if a plurality of (axial) first through holes distributed along the periphery is provided in the laminate core, wherein at least one recess of a first laminate section has a greater distance from the first through hole along the periphery than at least one recess of a second laminate section. Thus, the respective individual laminate preferably has a plurality of recesses at different distances from its nearest through hole, has at least two recesses, and more preferably has three recesses. This results in a suitable, non-uniform distribution of the recesses along the periphery.

[0014] In this case, it is also advantageous if the at least one recess of the first laminated core segment has a greater distance from the nearest through-opening of the at least one recess of the first laminated core segment along the outer circumference than the at least one recess of the third laminated core segment.

[0015] The stator can be realized in a particularly efficient manner if there are more than three laminated sections, preferably five or six laminated sections, each of which preferably comprises a sub-stack with several individual laminates.

[0016] Furthermore, the distribution of the coolant is advantageous if the depth (radial extent) of the recess of the respective lamination segment is less than 60%, more preferably less than 50%, of the width (extent along the outer circumference) of the recess of the respective lamination segment. This further reduces the tendency of the coolant to adhere / accumulate in the respective recess.

[0017] In other words, according to the invention, the positioning of the recesses on the wet-running stator is achieved to ensure cooling. In principle, two methods are proposed to improve the distribution of oil along the outer edge of the laminated core. One way to avoid continuous longitudinal recesses is to achieve independent recesses instead of longitudinal recesses by uneven distribution of the recesses ( / recesses) on the outer edge during the stamping process of the sheet, by rotating the sheet during assembly after the stamping process. Optimizing the position of these recesses can improve the fluid flow towards the center of the outer periphery of the laminated core. Another solution is to make the recess shallower and wider to prevent coolant accumulation and capillary forces in the recesses. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The invention is described in more detail below with reference to the accompanying drawings, in which various exemplary embodiments are shown.

[0019] In the attached picture:

[0020] Figure 1 shows a perspective view of a region of an electric machine according to a first exemplary embodiment, wherein the outer periphery of the stator is clearly visible,

[0021] Figure 2 Shows something like Figure 1 A perspective view of an electric machine of , in which arrows are additionally drawn in order to illustrate the flow direction of the coolant guided on the outer circumference during operation,

[0022] Figure 3 Shown in Figure 2 Detailed stereogram of the area marked “III” in

[0023] Figure 4 shows a front view of a motor according to the present invention,

[0024] Figure 5 Shown in Figure 4 Detailed view of the area marked “V” in

[0025] Figure 6 The individual laminates with recesses are shown as being inserted into Figures 1 to 5 A side view of a circumferential portion of the stator shown in FIG.

[0026] Figure 7 Shown is the insertion Figures 1 to 5 A three-dimensional view of the laminated core of the stator,

[0027] Figure 8 shows a perspective view of a laminated core for use in an electric machine according to a second exemplary embodiment, which is now provided with four through-holes instead of the three through-holes present in the first exemplary embodiment,

[0028] Fig. 9 shows a front view of individual laminations used to form a lamination core of a first exemplary embodiment,

[0029] Fig.10 shows 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 the distribution and arrangement of the recesses on the outer periphery of the laminated core,

[0030] Fig.11 Shows Fig.10 A perspective view of a laminated core of FIG. 1 , wherein arrows are now additionally drawn in to illustrate the flow direction of the coolant guided along the outer circumference during operation,

[0031] Fig.12 shows a top view of a portion of a sheet metal blank, with the individual laminations being represented by their outer contours, and

[0032] FIG. 13 shows a perspective view of a motor according to the prior art.

[0033] The accompanying drawings are only schematic in nature and are only used to understand the present invention. The same elements have the same reference numerals. In addition, the various features of different exemplary embodiments can in principle be freely combined with each other. DETAILED DESCRIPTION

[0034] Figure 1 The basic structure of the motor 1 according to the present invention is shown in the figure. Figure 1 The electric machine 1 provided in the embodiment is preferably used as a drive unit of a motor vehicle in its operation. The electric machine 1 has Figure 1 The housing 2 is partially shown in FIG. The stator 3 is mounted in the housing 2 so as to be fixed to the housing. Radially inside the annular stator 3, a rotor 4 of the electric machine 1 is arranged. The rotor 4 is mounted in a rotatable manner relative to the stator 3 and is further connected to a corresponding shaft of the motor vehicle in operation.

[0035] The rotation axis of the rotor 4 is Figure 117. The terms axial, radial and along / in the circumferential direction used herein all refer to the rotation axis 17. Thus, the axial direction is the direction along the rotation axis 17, the radial direction is the direction perpendicular to the rotation axis 17, and the circumferential direction is the direction along a circular line running coaxially with the rotation axis 17 or a circumferential line running around the rotation axis 17.

[0036] As in Figure 7 As shown in more detail in FIG. 1 , the stator 3 has a laminated core 6 as a base body. The laminated core 6 comprises a number of individual laminations 13, which are stacked on top of each other and are designed as identical components. In this embodiment, the individual laminations 13, each of which is formed to have a thickness of less than 1 mm, cannot be identified individually, but are shown for simplicity as being combined into sub-stacks 14. In this embodiment, a total of six sub-stacks 14 are shown by way of example, wherein each sub-stack 14 comprises a plurality of individual laminations 13 (preferably the same number of individual laminations 13) and is designated below as lamination segments 5a, 5b, 5c, 5d, 5e, 5f.

[0037] Also available in Fig. 9 The individual laminations 13 are observed in an exemplary manner in the figure. The individual laminations 13 have an annular extension. The individual laminations 13 have a number of radially extending slots 18 towards their radial inside, through which several wire windings of the wire winding area 7 extend in the fully assembled state of the stator 3. A circumferentially continuous annular area 19 extends radially outside the slots 18. The annular area 19 is provided with a plurality of through holes 16a, 16b, 16c distributed in the circumferential direction towards its radial outside. In the finally finished stacked state of the laminated core 6, the corresponding through holes 16a, 16b, 16c of the different individual laminations 13 are aligned with each other in the axial direction so as to be securely connected to the housing 2 via fastening means 20 (screws), such as can also be in Figure 4 Observed in.

[0038] Combination Fig.12 , shows the actual formation of the corresponding individual laminations 13. Fig.12 In FIG. 1 , a sheet metal blank 21 in the form of a sheet metal strip 22 / coil can be observed. The individual laminations 13 - whose radial outer contour / outer part 8 is Fig.12is pre-drawn into a punching edge - punched out of this sheet metal strip 22. In the punching operation, the individual laminations 13 are only punched out primarily from the sheet metal strip 22 in a typical manner. At several points marked with reference numerals 23, the individual laminations 13 are then still attached to the remaining sheet metal blank 21. Only after this, the individual laminations 13 are completely cut out. During this cutting process, corresponding recesses 9a, 9b, 9c, 9d in the form of recesses / notches distributed in the circumferential direction are formed in the individual laminations 13. In this respect, it should be noted that Fig.12 Point 23 in FIG. 1 is drawn arbitrarily to illustrate the general demoulding process and does not correspond to the subsequent bonding process. Figures 1 to 5 as well as Figure 7 The distribution according to the invention is shown in more detail.

[0039] Back to Figure 1 , the conductor winding region 7 is schematically shown as an annular region. The conductor winding region 7 extends beyond the laminated core 6 on its two axial sides and is connected substantially radially in an annular region 19 .

[0040] exist Figure 1 In the embodiment, the individual recesses 9a, 9b, 9c, 9d of the individual laminations 13 emerge from the common recesses 9a, 9b, 9c, 9d of the lamination segments 5a, 5b, 5c, 5d, 5e, 5f. The recesses 9a, 9b, 9c, 9d are arranged on the respective lamination segments 5a, 5b, 5c, 5d, 5e, 5f in a non-uniform distribution in the circumferential direction, i.e., in a distribution at different angular distances in the circumferential direction relative to the rotation axis 17. This is Fig. 9 It is also clearly shown in: Therefore, the first recess 9a is designed to be spaced apart from the first through hole 16a closest to it along the outer periphery 10 of the laminated core 6 by a first distance a. The second recess 9b is arranged at a second distance b from the second through hole 16b closest to it. The 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 from the first through hole 16a closest to it by a fourth distance d. In this embodiment, the first distance a and the fourth distance d are selected to be the same. The second distance b and the third distance c are different from each other, and the second distance and the third distance are different from the distance a and the distance d.

[0041] Although the individual laminations 13 of the same lamination section 5a, 5b, 5c, 5d, 5e, 5f are axially flush with their recesses 9a, 9b, 9c, 9d, the individual lamination sections 5a, 5b, 5c, 5d, 5e, 5f are arranged in a rotated manner relative to each other. Figure 1As can be observed again in FIG. 1 , this rotational arrangement results in the first recess 9a of the first lamination segment 5a being spaced apart from the second recess 9b of the second lamination segment 5b in the axial direction / along the outer periphery 10 and from the recesses 9a, 9b, 9c, 9d of the third lamination segment 5c. Therefore, the first recess 9a of the first lamination segment 5a is closed on its two axial sides by the corresponding end face 12 of the second lamination segment 5b and the corresponding end face 15 of the third lamination segment 5c. This results in the first recess 9a being axially closed in the sense of a groove, as can also be combined with Figure 2 and Figure 3 It is easy to observe. The first recess 9a then collects the coolant, which is oriented along the outer periphery 10 during operation and does not flow directly from the bottom of the first recess 9a toward the axial side of the first recess 9a. This arrangement of the first recess 9a of the first laminate section 5a also applies to the other recesses 9b, 9c, 9d. The recesses 9a, 9b, 9c, 9d of the other laminate sections 5b, 5c and 5d are also axially closed in this way. Only the laminate sections 5e and 5f arranged at the axial ends are open toward one axial side. The coolant continues to flow from the recesses 9a, 9b, 9c, 9d of the fifth laminate section 5e and the sixth laminate section 5f to the radial outside of the wire winding area 7.

[0042] Figure 5 The supply channel 24 of the coolant guide channel 11 is shown, which extends through the housing 2 and guides the coolant directly along the laminated core 6. The coolant entering the interior from the outside of the housing 2 is guided directly along the laminated core 6 through the coolant guide channel 11 formed between the outer circumference 10 and the housing 2, so that the stator 3 is directly wet-operated / directly liquid-cooled.

[0043] Figure 6 The preferred shapes of the respective recesses 9a, 9b, 9c, 9d are shown. It can be clearly observed here that each recess 9a, 9b, 9c, 9d forms a shallow / obtuse angle with respect to its peripheral inclined surface 25a, 25b. In particular, the depth (radial extent) of each recess 9a, 9b, 9c, 9d is less than half of the width, i.e. the circumferential extent. This prevents excessive accumulation of coolant in the recesses 9a, 9b, 9c, 9d during operation.

[0044] Figure 8 , Fig.10 and Fig.11 Two further exemplary embodiments of an electric machine 1 according to the invention are shown. In these figures, for the sake of clarity, only the laminated core 6 of the stator 3 is shown, wherein the further structure of the electric machine 1 as well as the further operating mode result from the first exemplary embodiment. Therefore, for the sake of brevity, only the differences from the first exemplary embodiment are described below.

[0045] pass Figure 8 In the second exemplary embodiment, a thicker laminate core 6 is realized. Eight sub-stacks 14 are stacked one on top of the other. As can be observed in this context, the individual recesses 9a, 9b, 9c, 9d of the laminate segments 5a to 5h are arranged along a zigzag line in the axial direction. In addition, in this embodiment, even four through holes 16a, 16b, 16c, 16d are provided.

[0046] Combination Fig.10 and Fig.11 It can also be observed that the distribution of the recesses 9a, 9b, 9c, 9d can be optimized in other ways. Thus, in this third exemplary embodiment, the recesses 9a, 9b, 9c, 9d closest to the common through holes 16a, 16b, 16c, 16d replicate the arrow profile.

[0047] In other words, according to the invention, the outer contour is designed so that despite the presence of process-related notches in the individual laminations 13, the liquid cooling medium can still flow along the side from the top to the bottom. Therefore, the notches 9a, 9b, 9c, 9d should not deflect the coolant so that the coolant leaves the side in the axial direction. Since notches, for example, notches formed in conjunction with the stamping of the sheet are indispensable, these notches must be designed accordingly. However, the geometry of the notches can only be varied within a limited range in terms of the depth and angle of the inlet. The advantage of this solution is that cooling with a liquid medium can be guaranteed without additional components such as cooling jackets, thereby reducing the necessary effort and costs. In the accompanying drawings, it can be observed that the special notch geometry and arrangement in the stator laminations 6 prevents the deflection of the coolant on the stator side. With regard to the solution of the invention, the geometry and positioning of the notches and the joining process are defined so that the cooling oil is not deflected axially outwards and therefore no longer contributes to cooling the side. In this case, continuous notches along the entire effective length must be prevented. This must be taken into account both when designing the individual laminations and when joining the individual laminations to form the laminate core.

[0048] In principle, deep and steeply tapering recesses slow down the incoming liquid significantly. In order to intercept as little oil as possible, the recesses must be as shallow as possible. Recesses that are as wide and shallow as possible prevent the incoming coolant from accumulating. In addition, this weakens the capillary effect and, therefore, the axial deflection of the oil. Another advantage of shallow recesses is that the strength losses generated in this area are reduced. However, due to the stamping process, a certain inlet and recess depth must be ensured. Therefore, the recess shape alone cannot prevent interception and capillary action. Since the geometry of the recess alone cannot prevent axial deflection, additional precautions must be taken in this regard to prevent the coolant from flowing out of the end faces. In order to prevent the liquid from flowing to the sides, the recesses are interrupted along the effective length in the laminated core. Due to this arrangement, when oil flows in, several droplets are formed in many recesses, and the axial walls prevent these droplets from flowing to the sides. The collection and outflow of the cooling liquid in the aforementioned example is Figure 2 and Figure 3 . It can be observed here that, due to the large number of interruptions in the notches, the axial outflow of the liquid can only take place in the outermost area. Most of the oil is collected in the notches in the center of the side and continues to flow as it accumulates. Overall, the loss of coolant on the side is expected to be very small. In addition, the part of the cooling oil that flows out axially at the end face can be used for additional cooling of the copper wire winding, which otherwise must be cooled by other means. In order to achieve such a recess arrangement in the stator laminations, the notches must be arranged accordingly in the individual laminations. If the notch positions are evenly distributed on the outer contour, completely continuous notches will be produced when the individual laminations are stacked to form the core. The first step to solve this problem is to distribute the stamped notches 9a, 9b, 9c, 9d unevenly. In order to obtain independent recesses instead of continuous notches in the laminated core, the individual laminations must be rotated relative to each other when stacked. In the example with three holes 16a, 16, 16c, three rotations can be performed, namely in each case a rotation of 120°; in the example with four holes ( Figure 8 ), two rotations can be performed, in each case by 180°. During the joining process, the stacking process can be freely varied. For example, the length of the recess can be varied by first forming smaller laminate cores with the same orientation as the sheets, which are then joined together to form the entire laminate core. Figure 3 In the , six smaller stacks are formed and then joined in a rotational manner relative to each other to form the entire stator laminate core. In addition, the concept can be optimized by defining a predetermined stacking sequence to optimize the coolant flow along the sides of the stator. Fig.10 In the embodiment of the invention, the stacking sequence has been defined so that the recesses are oriented like an arrow towards the center of the stator. This ensures that the outflowing coolant is also distributed more towards the center.

[0049] Reference numerals list

[0050] 1 Electric machine 2 Housing 3 Stator 4 Rotor 5a First laminated section 5b Second laminated section 5c Third laminated section 5d Fourth laminated section 5e Fifth laminated section 5f Sixth laminated section 6 Laminated core 7 Wire winding area 8 Exterior 9a First recess 9b Second recess 9c Third recess 9d Fourth recess 10 Outer periphery 11 Coolant guide channel 12 End face of second laminated section 13 Individual laminate 14 Substack 15 End face of third laminated section 16a First through hole 16b Second through hole 16c Third through hole 16d Fourth through hole 17 Axis of rotation 18 Groove 19 Annular area 20 Fastening device 21 Sheet metal blank 22 Sheet metal strip 23 Point 24 Supply channel 25a First inclined surface 25b Second inclined surface

Claims

1. An electric motor (1) for driving a motor vehicle, the electric motor comprising a housing (2), a stator (3) and a rotor (4), the stator being received in a fixed manner in the housing (2), the rotor being mounted rotatably relative to the stator (3), the stator (3) having a laminated core (6) comprising a plurality of stamped laminated segments (5a, 5b, 5c, 5d, 5e, 5f), and having a wire winding region (7) connected to the laminated core (6), and each laminated segment (5a, 5b, 5c, 5d, 5e, 5f) also having at least one radial recess (9a, 9b, 9c, 9d) produced by stamping on the radially outer portion (8) of the laminated segment, and a coolant guide channel (11) being directly delimited by the outer periphery (10) of the laminated core (6), characterized in that The recess (9a) of the first lamination section (5a) is spaced apart from the recess (9b) of the second lamination section (5b) directly adjacent to the first lamination section (5a) along the outer periphery (10), so that the recess (9a) of the first lamination section (5a) is at least partially axially covered by the end face (12) of the second lamination section (5b); wherein, A plurality of through holes (16a, 16b, 16c) distributed along the circumference are provided in the laminated core (6), wherein at least one recess (9a) of the first laminated section (5a) has a greater distance from the first through hole (16a) along the outer circumference (10) than at least one recess (9b) of the second laminated section (5b).

2. The electric machine (1) according to claim 1, characterized in that The first lamination section (5a) and / or the second lamination section (5b) comprises a single individual lamination (13) or a plurality of individual laminations (13) stacked on top of each other to form a sub-stack (14).

3. The electric machine (1) according to claim 1 or 2, characterized in that There is a third laminate section (5c) which is also provided with a recess (9c), and the third laminate section is adjacent to the axial side of the first laminate section (5a) facing away from the second laminate section (5b), wherein the recess (9c) of the third laminate section (5c) is spaced apart along the outer periphery (10) relative to the recess (9a) of the first laminate section (5a) so that the recess (9a) of the first laminate section (5a) is axially covered by the end face (15) of the third laminate section (5c).

4. The electric machine (1) according to claim 3, characterized in that The third lamination section (5c) comprises a single individual lamination (13) or a plurality of individual laminations (13) stacked on top of each other to form a sub-stack (14).

5. The electric machine (1) according to claim 2, characterized in that The individual laminations (13) of the lamination sections (5a, 5b, 5c, 5d, 5e, 5f) are designed as identical components, wherein at least one individual lamination (13) of the first lamination section (5a) is rotated relative to at least one individual lamination (13) of the second lamination section (5b).

6. The electric machine (1) according to claim 1, characterized in that Each lamination segment (5a, 5b, 5c, 5d, 5e, 5f) is provided with a plurality of recesses (9a, 9b, 9c, 9d) distributed along the outer periphery (10), wherein each recess (9a, 9b, 9c, 9d) of the corresponding lamination segment (5a, 5b, 5c, 5d, 5e, 5f) is arranged along the outer periphery (10) to be spaced apart from a separate recess (9a, 9b, 9c, 9d) of the adjacent lamination segment (5a, 5b, 5c, 5d, 5e, 5f).

7. The electric machine (1) according to any one of claims 3 or 4, characterized in that The at least one recess (9a) of the first lamination segment (5a) has a greater distance from the nearest through hole (16a) of the at least one recess of the first lamination segment along the outer periphery (10) than the at least one recess (9c) of the third lamination segment (5c).

8. The motor (1) according to any one of claims 1 to 2 and 4 to 6, characterized in that: There are more than three lamination sections (5a, 5b, 5c, 5d, 5e, 5f).

9. The motor (1) according to any one of claims 1 to 2 and 4 to 6, characterized in that: The depth of the recess (9a, 9b, 9c, 9d) of the corresponding laminated section (5a, 5b, 5c, 5d, 5e, 5f) is less than 60% of the width of the recess of the corresponding laminated section.

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