Stator for an electric machine, electric machine and motor vehicle

Abstract

The invention relates to a stator (10) for an electric machine, comprising a stator body (12) having a plurality of stator slots (14), wherein several conductors (22) are arranged one above the other in each stator slot (14) in the radial direction (R), and comprising several spacer elements (26, 34) which are configured to maintain a predetermined distance between the conductors (22) and a distance of the respective conductors (22) to a slot wall (18) of the stator body (12), whereby cooling channels (28) through which a cooling fluid can flow are kept clear within the stator slot (14), which are at least partially bounded by the respective conductors (22), whereby the cooling fluid can flow directly along the conductors (22), wherein each of the conductors (22) has an angular shape in its cross-section and each of the corners (24) of the angular shape of all conductors (22) is defined by a respective spacer element (26, 34).34) is supported against another conductor (22) and / or the groove wall (18).

Description

[0001] The invention relates to a stator for an electrical machine, an electrical machine with a stator and a motor vehicle with an electrical machine.

[0002] DE 10 2021 133 992 A1 discloses a stator for an electrical machine, comprising a stator body with a plurality of stator teeth arranged circumferentially and stator slots formed between the stator teeth and extending axially through the stator. Electrical conductors of a stator winding, arranged essentially radially one above the other, are accommodated in the stator slots. Along their radial extent, the stator slots have a slot base at their radially outer end and a slot opening at their radially inner end. The slot openings are each closed by a slot closure means. The stator slots are each separated from the stator windings by an insulation means, wherein the insulation means and the slot closure means are formed integrally, in particular monolithically, with one another.At least one of the insulating means may have a spacer element projecting into the respective stator slot, which spacers an electrical conductor from the insulating means to form a flow-through channel.

[0003] Furthermore, WO 2022 / 188916 A1 discloses a stator for an electrical machine, comprising a stator body with a plurality of circumferentially distributed stator teeth and stator slots formed between the stator teeth and extending axially through the stator. Stator windings arranged radially one above the other are accommodated in the stator slots, each of which is encased in insulation. The insulation bears against a stator slot, at least in some areas. The insulation has a rectangular cross-section. The insulation design includes contact sections at the four corners of the rectangular basic cross-section of the wave winding, which, together with a lateral surface of the stator slots, form cooling channels for direct slot cooling.

[0004] The object of the present invention is to provide a solution which enables direct slot cooling of conductors arranged in a stator slot and which makes it possible to limit vibrations of the conductors in the stator slot.

[0005] This object is achieved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0006] The invention relates to a stator for an electrical machine, in particular a traction machine of a motor vehicle. The traction machine is designed in particular to drive the motor vehicle using electrical energy from a vehicle battery. In addition, the electrical machine has a rotor which, during operation, is rotated relative to the stator about an axis of rotation. In particular, the stator is designed to be used in a radial flux machine. The stator comprises a stator body which can in particular comprise a multiplicity of stator laminations stacked on top of one another in a stacking direction and can thus be designed as a laminated core. The stacking direction of the stator laminations runs in particular parallel to the axis of rotation of the rotor of the electrical machine for which the stator is intended.

[0007] The stator body has a plurality of stator slots arranged circumferentially around a central axis of the stator. These stator slots extend in particular over the entire axial length of the stator, wherein the axial length runs parallel to the stacking direction or parallel to the axis of rotation of the rotor or parallel to a central axis of the stator. With respect to the radial direction of the stator, which is perpendicular to the axial direction, the stator slots run in particular in a star shape, starting from the central axis of the stator into the stator body. In each stator slot, several conductors are arranged one above the other in the radial direction running perpendicular to the central axis. These conductors can in particular be so-called hairpins. The conductors can in particular be designed as copper wires.

[0008] The stator further comprises a plurality of spacer elements which are designed to maintain a predetermined distance in the radial direction between the conductors and a distance of the respective conductors from a slot wall of the stator body that defines the associated stator slot. The respective spacer elements are formed separately from the conductors. Thus, the spacer elements are not part of an insulation of the respective conductors. In particular, the respective spacer elements each bear against at least one of the conductors in order to position this conductor or to maintain the distance of this conductor from another conductor and / or from the slot wall. By maintaining the respective distances, respective cooling channels through which a cooling fluid can flow are kept clear within the stator slot, which cooling channels are at least partially defined by the respective conductors.Because the cooling channels are at least partially defined by the respective conductors, the cooling fluid flows directly along the conductors when the stator is used as intended. The cooling fluid is designed to absorb heat from the respective conductors to cool them. Thus, direct cooling of the respective conductors can be achieved by the cooling fluid when the cooling fluid flows through the respective cooling channels. This allows the respective conductors to be cooled particularly efficiently.

[0009] In the stator, it is further provided that each of the conductors has an angular shape, in particular a rectangular shape, in its cross-section running perpendicular to the central axis. Furthermore, it is provided that each of the corners of the rectangular shape of all conductors is supported against a conductor and / or the slot wall by means of a respective spacer element. This means that each corner of each conductor in the stator slot is supported by means of an associated spacer element. This allows vibration of the respective conductors within the stator slot to be particularly well limited. Furthermore, the respective conductors can be particularly well positioned in the respective stator slots via the associated spacer elements.

[0010] In a possible further development of the invention, the conductors are clamped into the respective stator slots by means of the spacer elements. This means that the spacer elements are designed to press the conductors into the associated stator slot. For this purpose, the respective spacer elements can have an oversize and can be at least partially compressed to clamp the respective conductors into the stator slot. This ensures that the respective conductors are securely held in positions within the stator slot that are predetermined for each conductor.

[0011] In a further possible embodiment of the invention, it is provided that at least one of the spacer elements closes a slot opening of the associated stator slot radially inward towards the central axis. This means that at least one of the spacer elements has the shape of a slot closure wedge, at least in some regions, whereby the slot opening of this stator slot can be reliably closed inward towards the central axis by means of the region of this spacer element designed as a slot closure wedge. As a result, any leakage of cooling fluid guided in the stator slot, in particular cooling fluid guided in the cooling channels, from the stator slot via the slot opening can be limited, and in particular prevented. The guiding of the cooling fluid can thus be particularly well restricted to the cooling channels in the stator slot. The risk of leakage of the cooling fluid via the slot opening can thus be kept particularly low.This ensures that sufficient cooling fluid can flow through each of the cooling channels during operation, as leakage is prevented. This, in turn, ensures efficient and defined cooling of the respective conductors in the stator slot by means of the cooling fluid flowing through the cooling channels.

[0012] In this context, it can be provided in particular that the spacer element closing the slot opening has a U-shape. Each of the legs of the U-shape is applied to a corner of the square cross-section and thus to an edge of the conductor in this stator slot which has the shortest distance from the central axis of the stator in the radial direction. This means that the legs of the U-shape of the spacer element are applied to the innermost conductor in this stator slot with respect to the radial direction. An inner side of the spacer element facing this conductor, which forms the base of the recess of the U-shape, together with the conductor delimits a cooling channel. This cooling channel covers the radially innermost conductor in this stator slot in regions in the radial direction towards the central axis.Here, the inner side of the spacer element faces the side surface of the radially innermost conductor that faces the central axis of the stator. In other words, the spacer element closing the slot opening, together with the radially innermost conductor in this stator slot, defines one of the cooling channels, whereby the cooling fluid flowing through this cooling channel allows the radially innermost conductor to be cooled particularly efficiently on its side surface facing the central axis.

[0013] In a further possible embodiment of the invention, it is provided that at least one of the spacer elements is designed to support two corners of the respective cross-sectional shape of two different conductors against each other and against the groove wall. For this purpose, this spacer element can be arranged, in particular, in the radial direction between the respective conductors to be supported. As a result, a radially outwardly arranged first edge of a first conductor, which radially abuts the spacer element from the outside, and a radially inner edge of a second conductor, which radially abuts the spacer element from the inside, can be supported against each other by means of this spacer element. In addition, this spacer element abuts the groove wall in a circumferential direction running around the central axis, whereby the two corners of the respective angular cross-sections of these different conductors are supported against the groove wall.This means that this spacer element precisely defines the position of the respective corners of the cross-sections of the different conductors, both relative to each other and relative to the slot wall. The spacer element, which is arranged radially between the conductors arranged in a common stator slot, supports these different conductors, which are adjacent to each other in the radial direction, at corners of their cross-sections that face each other in the radial direction. These corners, supported by the spacer element, are arranged circumferentially facing the same slot wall of the stator slot.Because two edges of two different conductors are jointly supported by means of this at least one spacer element, the stator can be designed with particularly few spacer elements and thus in a particularly simple and particularly lightweight manner, in that all corners of the cross-section of all conductors within a stator slot are supported by means of particularly few spacer elements.

[0014] In a further possible embodiment of the invention, each side surface of each conductor defines at least one cooling channel in some areas. This ensures that, during operation, each side surface of each conductor is exposed to the cooling fluid flowing in the respective cooling channel and is thereby cooled. As a result, particularly uniform and reliable cooling of each of the conductors arranged in the stator slot can be achieved.

[0015] In a further possible embodiment of the invention, each of the slot walls defining the stator slot is insulated with slot insulation. This slot insulation can also be referred to as slot base insulation. This slot insulation serves to electrically insulate the laminated core from the conductors. Furthermore, the slot insulation serves to mechanically protect the conductors from sharp edges of the stator body. The slot insulation can be designed, for example, as paper insulation.

[0016] Furthermore, the invention relates to an electric machine with a stator as already described in connection with the stator according to the invention. The electric machine is, in particular, a traction machine for an electric motor vehicle. The electric machine is designed to drive the motor vehicle.

[0017] Furthermore, the invention relates to a motor vehicle having an electric machine as already described in connection with the electric machine according to the invention. The electric machine is configured to drive the motor vehicle using electrical energy.

[0018] Further features of the invention may emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0019] The drawing shows in the only figure ( Fig. 1) a schematic sectional view of a stator slot of a stator in which several conductors are arranged stacked one above the other in the radial direction.

[0020] In Fig. 1, a stator 10 for an electric machine of a motor vehicle is shown in section. The stator 10 comprises a stator body 12, which in the present case is designed as a laminated core. The stator body 12 has an at least substantially hollow-cylindrical geometry, wherein the stator body 12 is designed at least substantially symmetrically to a central axis of the stator 10. An axial direction A of the stator 10 runs in the longitudinal direction of the central axis of the stator 10. A radial direction R of the stator 10 is perpendicular to the axial direction A. In the Fig. In the figure shown in Figure 1, the axial direction A runs into the image plane. A circumferential direction U of the stator 10 runs around the central axis of the stator 10.

[0021] The stator body 12 has a plurality of stator slots 14 distributed in the circumferential direction U around the center axis of the stator 10. The stator slots 14 extend in particular over the entire length of the stator body 12 running in the axial direction A and in the radial direction R starting from the center of the stator 10 into the stator body 12. Respective stator slots 14 adjacent to one another in the circumferential direction U are delimited from one another by a stator tooth 16 arranged between these stator slots 14 in the circumferential direction U. An outer side of this stator tooth 16 forms a slot wall 18 delimiting the respective stator slot 14. As in Fig. 1, a slot insulation 20 is arranged in the stator slot 14 shown, which rests against the slot walls 18 delimiting this stator slot 14. As a result, the respective slot walls 18 are insulated by means of the slot insulation 20.

[0022] As in Fig. 1, several conductors 22 are arranged next to one another in the radial direction R in the stator slot 14. In the Fig. 1, the respective conductors 22 have at least substantially a rectangular cross-section. This means that the cross-section of the respective conductors 22 has at least substantially four corners 24. For reasons of clarity, only individual corners 24 of the respective conductors 22 are provided with the corresponding reference numerals. In order to enable particularly good cooling of the respective conductors 22 in the stator slot 14 and, moreover, to be able to particularly effectively limit vibrations of the conductors 22 in the stator slot 14, the stator 10 is provided with a plurality of spacer elements 26. A spacer element 26 is located at each corner 24 of each of the conductors 22.In order to be able to form the stator 10 with particularly few spacer elements 26, it is provided here that individual spacer elements 26 bear against corners 24 of the cross-section of conductors 22 that are immediately adjacent to one another in the radial direction R, said corners facing one another in the radial direction R. This means that two corners 24 of the cross-sectional shape of two different conductors 22 are supported against one another by means of a single spacer element 26. In the present case, it is further provided that each of the spacer elements 26 is supported against the slot wall 18 delimiting the stator slot 14. For this purpose, each of the spacer elements 26 bears against the slot insulation 20, which in turn bears against the respective slot walls 18.Thus, the edges of the respective conductors 22 corresponding to the corners 24 in cross-section are supported by the respective spacer elements 26 against the respective slot walls 18 and, if appropriate, additionally against respective further corners 24 of the cross-sections of further conductors 22. The spacer elements 26 thus enable the conductors 22 to be positioned particularly precisely in the stator slot 14. Furthermore, by supporting all corners 24 of the cross-sectional shape of each conductor 22, vibration of the respective conductor 22 within the stator slot 14 can be particularly effectively limited. Because the spacer elements 26 maintain respective distances between the conductors 22 from one another and between the conductors 22 and the slot wall 18, in particular the slot insulation 20, respective cooling channels 28 are formed. For reasons of clarity, only some of the cooling channels 28 are provided with the corresponding reference numerals.

[0023] The cooling channels 28 are designed to be flowed through by a cooling fluid, in particular cooling oil, during intended use of the stator 10 and during operation of the electrical machine having the stator 10. This implements direct slot cooling of the stator 10. In this case, the respective cooling channels 28 are each delimited at least in regions by at least one conductor 22. As a result, the cooling fluid flows during operation directly along the conductor 22 delimiting this cooling channel 28, whereby the conductor 22 can be cooled particularly well by means of the cooling fluid. In the present case, it is provided that each side surface 30 of each conductor 22 delimits at least one cooling channel 28. This ensures that, during operation, each side surface 30 of each conductor 22 is cooled by the flow of the cooling fluid. For reasons of clarity, only individual side surfaces 30 of the conductors 22 are provided with the corresponding reference numerals.

[0024] As in Fig.1, each stator slot 14 has a slot opening 32 at its inner end facing the central axis of the stator 10. In order to prevent the cooling fluid from escaping from the stator slot 14 via the slot opening 32, one of the spacer elements 26, which is designated below by the reference numeral 34, is provided with a U-shaped cross-section. This U-shaped spacer element 34 thus serves, on the one hand, as a slot closure wedge for the slot opening 32 and, on the other hand, to maintain the distance between the innermost conductor 22 with respect to the central axis of the stator 10 and the respective slot walls 18. For this purpose, the respective legs 36 of the U-shaped cross-section of the spacer element 34 each rest against a corner 24 of the innermost conductor 22 with respect to the radial direction R.Here, the legs 36 of the U-shaped cross-section of the spacer element 34 rest against the innermost corners 24 of the cross-section of the innermost conductor 22 with respect to the radial direction R. This innermost conductor 22 has the shortest distance from the center axis of the stator 10 in relation to all conductors 22 in this common stator slot 14.

[0025] An inner side 38 of the spacer element 34, which forms the bottom of the recess of the U-shaped cross-section of the spacer element 34, together with this first conductor 22, delimits one of the cooling channels 28. This cooling channel 28 partially covers the innermost conductor 22 in the radial direction R towards the central axis of the stator 10. The spacer element 34 having the U-shaped cross-section thus enables, on the one hand, this innermost conductor 22 to be reliably stabilized at all of its corners 24, that the slot opening 32 is reliably closed and thereby sealed, and furthermore, that due to the formation of the cooling channel 28 along the side surface of the innermost conductor 22 facing the central axis, the cooling fluid can flow during operation for particularly efficient cooling of the innermost conductor 22.

[0026] In particular, it is provided that the conductors 22 are clamped in the stator slot 14 by means of the respective spacer elements 26. The spacer elements 26 are combined spacer and clamping elements. The spacer elements 26 thus fulfill, on the one hand, a position-fixing function of the conductors 22 via their basic elasticity, which enables the conductors 22 to be clamped in the stator slot 14, and on the other hand, they keep the respective cooling channels 28 clear. Furthermore, the spacer elements 26 enable an at least substantially constant distance to be maintained between directly adjacent conductors 22 and all distances between adjacent conductors 22 to be at least substantially equal.

[0027] The described design of the stator 10 enables particularly good cooling of the stator 10. This stator 10 is particularly suitable for use in the high-performance sector. In the stator 10, high heat dissipation from the thermally highly stressed conductors 22 is possible due to the cooling fluid routing in the immediate vicinity of the conductors. In the stator 10, oil flow spaces near the conductors, in this case the cooling channels 28, are created by using the combined spacer and clamping elements – and thus the spacer elements 26. The spacer elements 26 are attached to the respective corners 24 of the cross-section of the conductors 22 between adjacent conductors 22 in the radial direction R and the stator slot 14 lined with the slot insulation 20.The design of the innermost spacer element 34 with respect to the radial direction R, which has the smallest distance from the center axis of the stator 10, with the U-shaped cross section enables heat dissipation near the air gap by means of the cooling fluid flowing in the cooling channel 28 delimited by this spacer element 34.

[0028] Overall, the invention shows how a conductor-near oil guide topology of an electric drive machine with direct slot cooling can be implemented. List of reference symbols 10 Stator 12 Stator body 14 Stator slot 16 stator teeth 18 groove wall 20 Slot insulation 22 ladders 24 Corner 26 Spacer element 28 cooling channel 30 side surface 32 groove opening 34 Spacer element 36 legs 38 Inside A axial direction R radial direction U circumferential direction QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 133 992 A1

[0002] WO 2022 / 188916 A1

[0003]

Claims

[1] Stator (10) for an electrical machine, comprising a stator body (12) having a plurality of stator slots (14) distributed in the circumferential direction (U) around a central axis of the stator (10), wherein in each stator slot (14) a plurality of conductors (22) are arranged one above the other in a radial direction (R) perpendicular to the central axis, and comprising a plurality of spacer elements (26, 34) which are designed to maintain a predetermined distance in the radial direction (R) between the conductors (22) and a distance of the respective conductors (22) from a slot wall (18) of the stator body (12) delimiting the associated stator slot (14), whereby respective cooling channels (28) through which a cooling fluid can flow are kept free within the stator slot (14), which cooling channels are delimited at least in regions by the respective conductors (22), whereby the cooling fluid can flow directly along the conductors (22),wherein each of the conductors (22) has a square shape in its cross-section running perpendicular to the central axis, and each of the corners (24) of the square shape of all the conductors (22) is supported against another conductor (22) and / or the groove wall (18) by means of a respective spacer element (26, 34). [2] Stator (10) according to claim 1, characterized by that the conductors (22) are clamped in the respective stator slots (14) by means of the spacer elements (26, 34). [3] Stator (10) according to claim 1 or 2, characterized by that at least one of the spacer elements (26, 34) closes a slot opening (32) of the associated stator slot (14) radially inwardly towards the central axis. [4] Stator (10) according to claim 3, characterized bythat the spacer element (26, 34) closing the slot opening (32) has a U-shape, each of the legs (36) of the U-shape rests on a respective corner (24) of the cross-section of that conductor (22) in this stator slot (14) which has the smallest distance from the central axis in the radial direction R, and an inner side (38) of the spacer element (26, 34) facing this conductor (22) together with the conductor (22) delimits a cooling channel (28) which partially covers the conductor (22) in the radial direction (R) towards the central axis. [5] Stator (10) according to one of the preceding claims, characterized by that at least one of the spacer elements (26) is designed to support two corners (24) of the cross-sectional shape of two different conductors (22) against each other and against the groove wall (18). [6] Stator (10) according to one of the preceding claims, characterized bythat each side surface (30) of each conductor (22) partially delimits at least one cooling channel (28). [7] Stator (10) according to one of the preceding claims, characterized by that each of the slot walls (18) delimiting the stator slots (14) is insulated with a slot insulation (20). [8] Electrical machine, comprising a stator (10) according to one of the preceding claims. [9] Motor vehicle, comprising an electric machine according to claim 8, which is designed to drive the motor vehicle by means of electrical energy.

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