Stator device, electric machine, and compressor

Abstract

The invention relates to a stator device (3) for an electric machine (1), comprising an at least partly cylindrical shell-shaped stator (8) which has at least one electrically conductive stator winding (10), wherein a respective winding head (12, 12) of the stator winding (10) protrudes from both axial end faces of the stator, and at least one of the winding heads is encased by a cylindrical shell-shaped impregnation (13). According to the invention, at least one end face of the impregnation (13) is equipped with a first cooling air guiding structure (15), and the housing (2) inner wall (25) facing the stator device has at least one recess (26) into which the cooling air guiding structure (15, 16) is inserted at least in some regions.

Description

[0001] Description

[0002] title

[0003] Stator device, electric machine and compressor

[0004] The invention relates to an electric machine for a motor vehicle, in particular a drive machine, with a rotatably mounted rotor and a stator device assigned to the rotor in a housing of the electric machine, wherein the stator device has a stator which is at least partially cylindrical in shape and has at least one electrically conductive stator winding, wherein the stator winding protrudes on both axial end faces of the stator with a respective winding head, and wherein at least one of the winding heads is encased by a cylindrical-shell-shaped impregnation (13).

[0005] Furthermore, the present invention relates to an electric compressor, in particular for a fuel cell, having a compressor wheel which is rotatably mounted in a compressor chamber and is operatively connected to an electric machine.

[0006] State of the art

[0007] Electrical machines of the type mentioned above are already known from the prior art. For example, published patent application EP 2 887 507 A1 discloses a method for impregnating a stator for an electrical machine. Impregnation protects, in particular, the stator winding and increases the service life of the electrical machine.

[0008] Disclosure of the invention

[0009] The electrical machine according to the invention with the features of claim 1 has the advantage that the stator device ensures improved cooling of the stator device and of an electrical machine having the stator device.By advantageously utilizing the housing, it is achieved, for example, that the air gap between the stator and rotor is advantageously cooled, as a result of which the electrical machine with this stator device achieves improved efficiency. According to the invention, a first cooling air guide structure is arranged on the impregnation on at least one end face, and that the housing has at least one recess in its inner wall facing the stator device, in which recess the cooling air guide structure is located at least in some areas. The stator device is, in particular, cylindrical overall at least in sections, with the winding heads and thus the impregnation on the winding heads also being cylindrical. In this respect, the outside is understood to mean the outer surface of the casing and the inside is understood to mean the inner surface of the casing of the impregnation.Cooling air or a cooling air stream is thus forced by the cooling air guide structure and the recess in the housing to flow around the cooling air guide structure, particularly along the circumference of the winding overhang or the stator device, thus advantageously contributing to the cooling of the stator device and the machine. The fact that the cooling air guide structure extends into the recess ensures that the cooling air stream cannot bypass the cooling air guide structure or bypass a cooling air structure. This permanently ensures optimal cooling of the electrical machine.

[0010] According to a preferred development of the invention, the cooling air guide structure is formed with a plurality of axially protruding and radially spaced cooling fins, which extend, in particular, at least substantially in the circumferential direction of the stator device along the respective end face. This ensures that the cooling air flow is guided over the entire end face of the stator device or the associated winding head, thus contributing to advantageous cooling.

[0011] The cooling fins are preferably formed integrally with the impregnation. As a result, the impregnation not only forms the known covering for protecting the stator winding, but also offers a structure that enables the targeted steering of a cooling air flow thanks to the cooling air guidance structure integrated into the impregnation. This cooling air guidance structure, formed integrally with the impregnation, ensures that a cooling air flow is advantageously guided during operation, in particular advantageous cooling of the associated winding overhang. As a result, the behavior of the electrical machine or the stator device in the electrical machine is advantageously influenced without the need for separate means, by simply adapting the geometry of the impregnation during its manufacture. The impregnation is preferably made of a silicone, epoxy, thermoset and / or thermoplastic material.Alternatively, the cooling fins are designed as separate components and are held in the impregnation in a form-fitting manner with a holding foot, in particular partially covered by the impregnation, on / in the impregnation.

[0012] Preferably, a cooling air guide structure (15, 16) is formed on each of the two end faces of the impregnation (13). In particular, the cooling air guide structures are of identical design, but mirrored on a stator center plane that is perpendicular to the rotational or cylindrical axis of the stator device. Alternatively, the cooling air guide structures differ from one another. Preferably, the cooling fins of the respective cooling structure are designed or arranged radially evenly spaced from one another in order to form air guide channels of equal size or width between them, which ensure an advantageous distribution of the air flow or multiple cooling air flows. Furthermore, it is preferably provided that at least one of the cooling fins runs in a screw-like or thread-like manner, in particular such that it forms at least one thread structure or at least one thread turn.As a result, the cooling air flow is guided not only in the circumferential direction, but also radially along the end face, preferably from the outside to the inside, to ensure advantageous cooling of the end face and to ensure that the cooling air flow is also directed inward in a targeted manner toward the center of the stator or a rotor and / or a bearing point of a rotor shaft of the rotor. According to a preferred embodiment of the invention, the plurality of cooling fins are formed by a helically extending cooling fin.

[0013] The housing preferably has at least one recess for only one or for both cooling air structures. For example, it is provided that the stator device is located with one end face axially spaced from the housing wall, and on the end face facing away from it, the cooling air guide structure projects into the recess in the housing formed there. Optionally, the stator device projects on both of its end faces, each with a cooling air guide structure, into one or at least one respective recess in the housing. The respective recess in the housing is thus formed axially with respect to the rotational axis of the rotor or extends axially into the housing.

[0014] Furthermore, it is preferably provided that the at least one recess is designed to accommodate one or more cooling fins of one of the cooling air guide structures. As a result, the respective cooling air guide structure with the one or more cooling fins protrudes axially into the recess. This ensures that the cooling air flows advantageously around the cooling fins. Likewise, the air guide channel located between the adjacent cooling fins is advantageously flowed through by the cooling air flow.

[0015] Furthermore, it is preferably provided that the housing has a recess for at least two cooling fins of a cooling air guide structure. According to this embodiment, a separate recess is formed in the housing wall for each individual cooling fin. This can, for example, ensure that the volume flow of the cooling air varies in different areas of the cooling air guide structure.

[0016] According to a preferred development of the invention, at least one of the cooling fins protrudes axially further or closer than the other cooling fins of the respective cooling air guide structure from the respective end face. As a result, the cooling fins of the respective cooling air structure are designed to protrude axially to different extents, which offers advantages, for example, when redirecting the cooling air flow into the cooling air guide structure. For example, a cooling fin or a section or longitudinal section of a cooling fin that is opposite an inlet opening for the cooling air flow of the housing is designed to be shorter than the other cooling fins of this cooling air guide structure in order to advantageously accommodate the cooling air flow guided through the inlet opening and direct it into the air channels between adjacent cooling fins.

[0017] In particular, the stator is mounted in a stator chamber of the housing of the electrical machine, wherein the housing has at least one inflow channel for cooling air, which opens into the stator chamber through an inflow opening, wherein the cooling air guide structure is assigned to the inflow opening, in particular opposite it, in order to advantageously forward the supplied cooling air flow.

[0018] The electric machine preferably has a cooling device, with the inflow channel passing through the cooling device. This ensures that the cooling air supplied to the stator device is cooled or can be cooled if necessary, thus contributing to high heat dissipation.

[0019] The stator chamber preferably has an axial length that is only slightly greater than the axial length of the stator device, leaving a ventilation gap axially between the impregnation and the housing. This ensures that the cooling air flow, or a portion of the cooling air flow, reaches radially inward toward the rotor or bearing points of the electric machine. The axial length also includes the cooling fin penetrating the respective recess. A distance preferably remains axially between the respective cooling fin and the bottom of the respective recess, forming the ventilation gap.

[0020] The compressor according to the invention with the features of claim 11 is characterized by the inventive design of the electric motor. This results in the advantages already mentioned above.

[0021] Preferably, an inlet opening of the inflow channel opens into the

[0022] Compressor chamber. Thus, the inflow channel leads from the compressor chamber to the stator device, with the inflow channel optionally passing through the aforementioned cooling device. Thus, during operation of the electric compressor, the cooling air is taken from the compressor chamber or the compressor chamber. Because the air is compressed in the compressor chamber and thus has an increased air pressure, it is conveyed into the inflow channel during operation and thus to the stator device. This results in an advantageous high cooling capacity for the stator device.

[0023] Further advantages and preferred features and combinations of features emerge in particular from the above description and from the claims. The invention will be explained in more detail below with reference to the drawings. The sole

[0024] Figure shows an advantageous electric compressor with an electric machine in a simplified sectional view.

[0025] Figure 1 shows an advantageous electric machine 1 of an electric compressor 14 in a simplified sectional view, with only a portion of the electric machine 1 shown above a rotational axis 6. The electric machine 1 has a housing 2 in which a stator 3 is mounted in a rotationally fixed manner and a rotor 4 is mounted in a rotationally fixed manner. The rotor 4 is mounted on a rotor shaft 5, the rotational axis 6 of which is also shown in Figure 1.

[0026] The stator 3 is circularly cylindrical and surrounds the rotor 4 radially or is arranged coaxially with it. The rotor shaft 5 is advantageously held in the housing 2 by one or more rolling element bearings or other friction-reducing bearings.

[0027] The stator 3 is arranged in a stator chamber 7 of the housing 2. The stator device 3 comprises a stator 8, which is made in particular of metal and in particular has a plurality of stator teeth 9 arranged evenly distributed over the circumference of the stator and projecting radially inward. Furthermore, the stator device 3 comprises a stator winding 10, which has winding heads 11 and 12 projecting axially from the stator 8 on both sides.

[0028] Furthermore, the stator winding 12 has a coating in the form of an impregnation 13. The impregnation 13 is made, in particular, of an epoxy material, silicone, thermoplastic, and / or thermoset, and is produced, in particular, by a casting or injection molding process. The impregnation 13 completely surrounds, in particular, the winding heads 11 and 12, thereby advantageously protecting the stator winding 12 from external influences and damage. This advantageously increases the durability of the electrical machine 1.

[0029] On the axial end faces of the stator device 3, the impregnation 13 is optionally manufactured with a thickness greater than the remaining impregnation thickness. In the area of ​​the winding heads 11, 12, the impregnation 13 has a cooling air guide structure 15 and 16, respectively.

[0030] The first cooling air guide structure 15 has a plurality of cooling fins 17 projecting axially from the end face, which are radially spaced from one another and thus form an air guide channel between them, and the second cooling air guide structure 16 has a plurality of cooling fins 18 projecting axially from the end face, which are also radially spaced from one another and thus form an air guide channel between them. The cooling fins 17, 18 are each located radially between an outer side 19 of the stator device 3 or the impregnation 13 and an inner side 20 of the impregnation 13.

[0031] The cooling fins 17, 18 each extend over the circumference of the respective end face of the impregnation 13, so that the air guide channels formed between them also extend over the circumference. According to a first exemplary embodiment, the cooling fins 17, 18 extend exactly along a circumferential line to the rotation axis 6 and thus form annular or circular cooling fins 17, 18. According to a further exemplary embodiment, at least the cooling fins 17, optionally also 18, run helically over the respective end face, so that they lead from the outside to the inside in a thread or thread pitch. In this respect, the plurality of cooling fins 17 shown in section form a continuous, helical cooling fin.The helical course ensures that a cooling air flow is guided into the interior of the stator 8 or the stator device 3, in particular in the direction of the stator center and the rotor 4, and if necessary to bearing points of the rotor shaft 5.

[0032] The cooling fins 17 and 18 are of identical design and are merely arranged in a mirror image of each other. According to an alternative embodiment shown in Figure 1, the air guide channels 17, 18 are designed differently.

[0033] According to the present exemplary embodiment, at least one of the cooling fins 17 is axially shorter than the other cooling fins 17. This cooling fin 17 thus protrudes less axially in the direction of the housing wall than the other cooling fins. The shortened cooling fin 17 is preferably located opposite the inflow opening 28. This ensures that the cooling air flowing into the stator chamber 7 through the inflow channel 29 is advantageously distributed in the cooling air structure 15. In particular, this advantageously enables the cooling air flow to be introduced into a plurality of cooling channels formed between the adjacent cooling fins 17. The shortened design also enables an advantageous deflection of the cooling air flow in the circumferential direction of the end face along the cooling fin 17, which, for example, is annular or helical.The shortened design of the at least one cooling fin 17 either extends over the entire length of the then circular ring-shaped cooling fin, or one or more of the cooling fins 17 are only axially shortened in sections, namely in the vicinity of or in the region of the inflow opening 28, and thus protrude less axially than the other cooling fins in order to achieve the above-mentioned advantages.

[0034] The housing 2 has a plurality of inflow channels 21, 22 leading into the stator chamber 7. The inflow channels 21, 22 open into the stator chamber 7 through inflow openings 23, 24, which are radially assigned to the end faces of the stator device 3. The cooling fins 17 are designed and / or arranged in this case such that their air guide channel, formed at least between two adjacent cooling fins 17, is opposite a further inflow opening 28 that opens axially into the stator chamber 7, so that the supplied cooling air reaches the air guide channel between the cooling fins 17 directly.

[0035] Preferably, the electric machine also has a cooling device 32, which is located in particular in the inflow channel 21, so that the supplied cooling air can be cooled as needed and thus the heat dissipation from the electric machine 1 can be optimized.

[0036] Through a ventilation gap between the respective end face of the stator device 3 and the inside of the housing 2 at the stator chamber 7, the cooling air flow continues to the rotor 4 and into the air gap 27 between rotor 4 and stator 8. For this purpose, the stator chamber 7 has an axial length that is only slightly larger than the axial length of the stator device

[0037] The axial or lateral inflow opening 28 opens into a further inflow channel 29 of the housing 2. The cooling air flow can thus reach the cooling air guide structure 15 both through the inflow opening 23 and through the further inflow opening 28, which opens axially to the stator device 3 into the stator chamber 7.

[0038] An inlet opening 33 of the inflow channel 29 preferably opens into a compressor chamber 34 of the compressor 14, in which a compressor wheel (not shown here) is rotatably mounted and connected to the rotor shaft 4 for its drive. During operation, this creates an overpressure in the compressor chamber 34, which forces air from the compressor chamber 34 through the inlet opening 33 into the inflow channel 33, optionally through the cooling device 32, and subsequently into the cooling air structure 15 and / or 16.

[0039] Advantageously, the housing 2 has, on its inner wall 25 opposite the cooling air guide structure 16, a recess 26 extending axially into the housing 2, into which the cooling fins 18 of the cooling air guide structure 16 protrude. This ensures that the cooling air flow, which reaches the stator chamber 7 from the inflow channel 22, cannot flow past a cooling air guide structure 16, but rather is forced through the cooling air guide structure 16. This increases the cooling efficiency for the electrical machine 1. A corresponding design, with a recess 26, into which at least some of the cooling fins

[0040] 17, is optionally also present on the other axial side of the electrical machine 1.

[0041] While according to the present embodiment, the cooling fins 17, 18 are formed integrally with the impregnation 13, according to a further embodiment not shown here, it is provided that the cooling fins 17, 18 are manufactured as separate components, in particular from material with high thermal conductivity, in particular with higher conductivity than the impregnation 13, and are enclosed or partially enclosed by the impregnation 13. In particular, the cooling fins 17,

[0042] 18 each have a support foot, which is surrounded by the material of the impregnation 13 in a form-fitting and play-free manner. Optionally, several of the cooling fins 17, 18 have a common support foot.

[0043] While according to the present exemplary embodiment, the recess 26 accommodates all cooling fins 18, according to a further exemplary embodiment, the recess 26 is divided into several sections, so that, for example, each or more of the cooling fins 18 each dip into or protrude into its own recess. Such a division is indicated by dashed lines in the figure as an example.

Claims

Claims 1. An electrical machine (1) for a motor vehicle, in particular a drive machine, having a rotatably mounted rotor (4) and a stator device (3) assigned to the rotor (4) in a housing (2) of the electrical machine, wherein the stator device (3) has a stator (8) which is at least partially cylindrical in shape and has at least one electrically conductive stator winding (10), wherein the stator winding (10) protrudes from both axial end faces of the stator with a respective winding head (12, 12), and wherein at least one of the winding heads is encased by a cylindrical impregnation (13), characterized in that a first cooling air guide structure (15) is arranged on the impregnation (13) on at least one end face, and in that the housing (2) has at least one recess (26) in its inner wall (25) facing the stator device, in which recess the cooling air guide structure (15, 16) is located at least in part.

2. Electrical machine (1) according to claim 1, characterized in that the cooling air guide structure is formed with a plurality of axially projecting and radially spaced cooling fins (17, 18) which extend in particular at least substantially in the circumferential direction of the stator device (3) along the respective end face.

3. Electrical machine (1) according to one of the preceding claims, characterized in that a cooling air guide structure (15, 16) is formed on each of the two end faces of the impregnation (13).

4. Electrical machine (1) according to one of the preceding claims, characterized in that the housing has at least one recess (26) for only one or for both cooling structures (15, 16).

5. Electrical machine (1) according to one of the preceding claims, characterized in that the at least one recess (26) is designed is designed to accommodate one or more cooling fins of one of the cooling air guide structures.

6. Electrical machine (1) according to one of the preceding claims, characterized in that at least one of the cooling fins (17, 18) projects axially further or less far from the respective end face than the remaining cooling fins (17, 18) of the respective cooling air guide structure (15, 16).

7. Electrical machine (1) according to one of the preceding claims, characterized in that the housing (2) has a recess (26) for at least two cooling fins (18) of a cooling air guide structure (18).

8. Electrical machine (1) according to claim 7, characterized in that the stator (8) is mounted in a stator chamber (7) of the housing (2) of the electrical machine (1), wherein the housing (2) has at least one inflow channel (21, 22, 29) for cooling air, which opens into the stator chamber (7) through an inflow opening (23, 24, 28), and that the respective cooling air guide structure (15, 16) is assigned to at least one inflow opening (23, 24, 28), in particular is opposite it.

9. Electrical machine according to claim 8, characterized in that a cooling device (32) is provided, and that at least one inflow channel (21) leads through the cooling device (32).

10. Electrical machine according to one of claims 7 to 9, characterized in that the stator space has an axial length which is only slightly greater than the axial length of the stator device (3), so that a ventilation gap remains axially between the impregnation (13) and the housing (2).

11. Electric compressor (14), in particular for a fuel cell, with a compressor wheel which is rotatably mounted in a compressor chamber (34) and is operatively connected to an electric machine (1), characterized by the design of the electric machine according to one of claims 7 to 12. Electric compressor according to claim 11, characterized in that an inlet opening (33) of an inflow channel (29) opens into the compressor chamber (34).

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