Stator for an electric machine having a device for cooling the stator

Abstract

The invention relates to a stator (1) for an electric machine (22), comprising: a laminated stator core (2); a stator winding (3), the laminated stator core (2) and the stator winding (3) being designed to generate a rotating electric field when a current flows therethrough; and means for cooling the stator (1) with a coolant, in which the means comprise a hollow cylindrical stator sheath (7) surrounding the laminated stator core (2) and the stator windings (3) and having radial inlets (9), helically extending protrusions (13) being formed on the inner face of the stator sheath (7), which protrusions (13) together with the outer face of the laminated stator core (2) form channels for the coolant. The invention further relates to a method for producing the stator (1), to an electric machine (22), and to a vehicle (17) having an electric machine (22).

Description

Technical Field

[0001] The invention relates to a stator for an electric machine, having a laminated stator core and a stator winding, wherein the stator core and the stator winding are designed to generate a rotating electric field in a current-carrying state, and having a device for cooling the stator with a cooling liquid. Background Art

[0002] Electric machines of this type are increasingly being used in electric vehicles or hybrid vehicles. They are primarily used as electric motors for driving vehicle wheels or axles. Electric motors can be designed in particular as synchronous motors or asynchronous motors.

[0003] The electric motor is in most cases mechanically coupled to a gear unit for speed regulation. In addition, the electric motor is usually electrically connected to an inverter which generates an AC voltage, in particular a multiphase AC voltage, for the motor operation from a DC voltage supplied by a battery.

[0004] It is also possible to operate the electric machine as a generator for recovering kinetic energy of the vehicle, wherein the kinetic energy is first converted into electrical energy and then into chemical energy for the battery.

[0005] The stator of a conventional electric motor typically has a laminated stator core and stator windings. When current is applied to the stator windings, a rotating electric field is generated, which causes the rotor to rotate.

[0006] During operation of the electric motor, the stator in particular heats up significantly, with the amount of heat generated being proportional to the applied current. When the motor is operated at high output, a particularly high amount of heat is generated. However, in the process, certain components of the motor, such as the stator winding, reach their thermal load limits.

[0007] In order to be able to dissipate the generated heat, the stator usually has a cooling device. The cooling device can include a cooling duct through which a liquid coolant flow can be passed. The coolant can be, for example, a water / glycol mixture or oil, which is conveyed in a circuit. This allows the temperature of the stator winding to be kept below specified limits even under high loads.

[0008] The cooling of the stator should be as uniform as possible to avoid local hot spots. For this purpose, conventional electric machines are equipped with a cooling jacket, for example through which water flows. However, providing a cooling jacket requires that the cooling jacket be integrated into the structure of the electric machine.

[0009] Therefore, there is a need for a stator with an easily integrated cooling device. Summary of the invention

[0010] To achieve this object, according to the invention, in a stator of the type mentioned at the outset, the device comprises a hollow cylindrical stator jacket which surrounds the laminated stator core and the stator winding and has a radial inlet, a helically extending protrusion being formed on the inner side of the stator jacket which, together with the outer side of the laminated stator core, forms a duct for a cooling liquid.

[0011] The invention is based on the finding that it is particularly easy to provide a stator with cooling by arranging the cooling device on the outside of the laminated stator core. For this purpose, the laminated stator core is surrounded by a stator jacket designed as a hollow cylinder. Inside the hollow cylinder there are helical protrusions which together with the outside of the laminated stator core form cooling ducts.

[0012] Such a stator has the advantage that no modification of the laminated stator core is required. A stator jacket can be easily attached to the outside, thereby forming a cooling duct. Thus, a stator can be provided with a cooling device for a cooling liquid in an extremely simple manner, wherein the cooling is performed from the outside of the laminated stator core.

[0013] In the context of the invention, it can be provided that a radial inlet for the cooling liquid is arranged at least approximately in the center of the stator jacket in the axial direction and that a spiral duct for the cooling liquid extends from the inlet to both axial ends of the stator jacket. This arrangement of inlet and duct ensures that the cooling liquid supplied from the center of the stator jacket flows in the direction of both ends of the stator jacket, thereby dissipating heat particularly evenly.

[0014] In order to simplify the manufacture of the stator according to the invention, it is particularly preferred that the stator jacket has a first half shell and a second half shell connected to the first half shell. The two half shells are first positioned around the laminated stator core and then connected to each other. Preferably, the two half shells can be welded and / or glued and / or locked to each other. In this way, the laminated stator core including the stator winding can be provided with the stator jacket in a relatively late assembly step.

[0015] Preferably, the interconnecting edges of the half shells define a separation plane in which the first half shell has one or more recesses and the second half shell has one or more projections which are formed complementary to the recesses and are inserted into and / or locked to the recesses. By locking the two half shells, the latter can be connected to each other particularly easily.

[0016] Preferably, the two half-shells forming the stator jacket are made of plastic material.

[0017] Furthermore, the half shells can preferably be produced by injection molding.

[0018] In order to ensure cooling of the winding heads of the stator winding, a ring with passage openings is preferably provided on one or both axial sides of the stator. The coolant supplied via the cooling duct can be supplied to the winding heads of the stator winding through the ring, in particular through the passage openings provided in the ring, in order to cool the stator winding.

[0019] The invention also relates to a method for producing a stator of the type described for an electric machine, comprising the following method steps:

[0020] - providing a laminated stator core provided with a stator winding;

[0021] - arranging a first half shell and a second half shell of a stator jacket around the laminated stator core; and

[0022] - connecting the first half shell and the second half shell so as to form a hollow cylindrical stator jacket.

[0023] The invention further relates to an electric machine having a stator of the type described, which surrounds a rotor which is rotatable relative to the stator.

[0024] Optionally, the electric machine can have a housing surrounding the stator. However, this can also be an electric machine without a housing, in which the outside is formed by the stator itself and two axial covers or flanges.

[0025] In the electric machine according to the present invention, the coolant may include oil.

[0026] According to a further development of the electric machine according to the invention, the electric machine has a flange with a plurality of passage openings for fastening the electric machine, wherein an inlet of the stator jacket for the cooling liquid is arranged in the circumferential direction so as to be adjacent to one of the passage openings. This arrangement is particularly space-saving since the inlet does not extend beyond the outer contour of the flange.

[0027] Furthermore, the inlet opening may be arranged such that it is co-aligned with the passage opening in the axial direction, which facilitates mounting of the electric machine in a vehicle.

[0028] The object on which the invention is based is also achieved by a vehicle having an electric machine according to the invention, which is configured to drive the vehicle.

[0029] Furthermore, the vehicle may have a gear unit coupled to the electric machine and / or an inverter connected to the electric machine, by means of which the multi-phase AC voltage required for operating the electric machine may be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be explained below by means of exemplary embodiments with reference to the accompanying drawings. The accompanying drawings are schematic diagrams, in which:

[0031] Figure 1 shows a cross-sectional view of an electric machine having a stator according to the invention;

[0032] Figure 2 shows a perspective view of a stator jacket connected to a flange;

[0033] Figure 3 shows a cross-sectional view of the inside of a stator jacket;

[0034] Figure 4 An enlarged detail showing the separation plane of the two interconnected half shells of the stator casing; and

[0035] Figure 5 A motor vehicle according to the invention is shown. DETAILED DESCRIPTION

[0036] Figure 1 A cross-sectional view of an electric machine 22 having a stator 1 according to the invention is shown. The stator 1 comprises a laminated stator core 2 and a stator winding 3. The stator winding 3 generates a rotating electric field when an electric current is applied.

[0037] exist Figure 1 There is a flange 4 on the left side. Figure 1 The right side of the stator 1 has an axial cover 5. The rotor shaft of the rotor 6 with a cavity is located in the center of the stator 1. The flange 4 has a central opening through which the rotor shaft passes.

[0038] The stator 1 has a device for cooling, which has a hollow cylindrical stator jacket 7. Figure 1 As can be seen in FIG, the stator jacket 7 surrounds the laminated stator core 2 with the stator winding 3. The stator jacket 7 has a coolant line 8 extending parallel to the axial direction and opening into a radial inlet 9. The coolant line 8 is connected to a coolant reservoir via a line not shown. With the help of a pump, the coolant is conveyed into the stator jacket 7 in a circuit through the coolant line 8 and the radial inlet 9.

[0039] Rings 23 with passage openings are located each on two axial sides of the stator winding 3 , thus respectively within the flange 4 or the axial cover 5 , in order to guide the coolant to the winding heads 24 of the stator winding 3 .

[0040] Figure 2 A perspective view of the stator jacket 7 connected to the flange 4 is shown. Figure 2 As can be seen in FIG. 1 , the axially extending coolant lines extend from the axial ends to the approximate center of the stator jacket 7. The stator jacket 7 comprises a first half shell 10 and a second half shell 11 which are connected to each other and form the annular stator jacket 7.

[0041] Figure 3A cross-sectional view of the stator jacket 7 is shown, showing the inner side of the latter. It can be seen that there are helically extending protrusions 13, which, starting from the inlet 9 for the coolant, extend symmetrically in two opposite axial directions. In the radial direction, the protrusions 13 extend to the outer side of the stator winding 3. Thereby, a cooling duct 14 is formed which is delimited by the inner side 12 of the stator jacket 7, the helically extending protrusions 13 and the outer side of the stator winding 3.

[0042] The cooling duct 14 spirally extends outward from the center of the stator jacket 7 in both axial directions. Therefore, the coolant supplied via the coolant line 8 and the inlet 9 is guided through the cooling duct 14 spirally wound around the outside of the stator jacket 7, whereby heat is optimally dissipated from the laminated stator core 2 and the stator winding 3. When the motor 1 is operated, the temperature of the stator winding 3 can be limited to a specified value.

[0043] Figure 4 An enlarged fragment of a separation plane of two interconnected half shells 10, 11 of a stator jacket 7 is shown. The first half shell 10 has a recess 15 formed as a groove extending over the entire axial length of the first half shell 10. The second half shell 11 has a projection 16 which has a design complementary to the latter and which also extends over the entire axial length of the second half shell 11. Each half shell 10, 11 has such a recess 15 and such a projection 16, on which the two half shells 10, 11 can be locked or pressed together to form the tubular stator jacket 7. In other embodiments, the connection of the two half shells 10, 11 can also be made by gluing or welding.

[0044] Figure 5 A vehicle 17 is shown having a drive train including an electric motor 22. The electric motor 22 is coupled to wheels 19 of the vehicle 17 via a gear unit 18. Furthermore, the electric motor 22 is electrically connected to an inverter 20. A battery 21 supplies a DC voltage which is converted by the inverter 20 into an AC voltage for the operation of the electric motor 22.

[0045] Reference numerals list

[0046] 1 Stator

[0047] 2 Laminated stator core

[0048] 3 Stator winding

[0049] 4 Flange

[0050] 5 Axial cover

[0051] 6 Rotor

[0052] 7 Stator jacket

[0053] 8 Coolant lines

[0054] 9 Entrance

[0055] 10 First Half Shell

[0056] 11 The Second Half Shell

[0057] 12 Inside

[0058] 13 Protrusion

[0059] 14 Cooling duct

[0060] 15 concavity

[0061] 16 Protrusion

[0062] 17 Vehicles

[0063] 18 Gear Unit

[0064] 19 Wheel

[0065] 20 Inverter

[0066] 21 Batteries

[0067] 22 Motor

[0068] 23 rings

[0069] 24 Winding head

Claims

1. A stator (1) for an electric machine (22), comprising a laminated stator core (2) and a stator winding (3), wherein the laminated stator core (2) and the stator winding (3) are designed to generate a rotating electric field in a current-carrying state, and having a device for cooling the stator (1) with a cooling liquid, characterized in that: The device comprises a hollow cylindrical stator jacket (7) which surrounds the laminated stator core (2) and the stator winding (3) and has a radial inlet (9), on the inner side of which are formed helically extending protrusions (13) which together with the outer side of the laminated stator core (2) form a duct for the coolant.

2. The stator according to claim 1, wherein: The inlet (9) for the cooling liquid is arranged at least approximately in the center of the stator jacket (7) in the axial direction, and a spiral duct for the cooling liquid extends from the inlet (9) to both axial ends of the stator jacket (7).

3. The stator according to claim 1 or 2, wherein: The stator jacket (7) has a first half shell (10) and a second half shell (11) connected to the first half shell (10).

4. The stator according to claim 3, wherein: The two half shells (10, 11) are welded and / or glued and / or locked to one another.

5. The stator according to claim 3 or 4, wherein: The interconnected edges of the half shells (10, 11) define a separation plane, in which the first half shell (10) has one or more recesses (15) and the second half shell (11) has one or more protrusions (16), which are formed to be complementary to the recesses (15) and are inserted into and / or locked to the recesses (15).

6. The stator according to any one of claims 3 to 5, wherein: The two half shells (10, 11) are made of plastic material.

7. The stator according to any one of claims 3 to 6, wherein: The two half shells (10, 11) are produced by injection molding.

8. A stator as claimed in any one of the preceding claims, wherein: A ring (23) is arranged on one or both axial sides of the stator (1), the ring (23) having a passage opening for supplying coolant from the duct to the winding heads (24) of the stator winding (3).

9. A method for producing a stator (1) for an electric machine (22) according to any one of claims 1 to 8, comprising the following method steps: - providing a laminated stator core (2) having a stator winding (3); - a first half shell (10) and a second half shell (11) of a stator jacket (7) are arranged around the laminated stator core (2); and - Connecting the first half-shell (10) and the second half-shell (11) so as to form the hollow cylindrical stator jacket (7).

10. An electric machine (22) comprising a stator (1) as claimed in any one of claims 1 to 8, the stator surrounding a rotor which is rotatable relative to the stator (1).

11. The electric machine (22) according to claim 10, wherein: The coolant includes oil.

12. The electric machine (22) according to claim 10 or 11, having a flange (4) with a plurality of passage openings for fastening the electric machine (22), wherein: The inlet (9) of the stator jacket (7) for the cooling liquid is arranged in the circumferential direction so as to be adjacent to one of the channel openings.

13. The electric machine (22) of claim 12, wherein: The inlet (9) is co-aligned with the passage opening in the axial direction.

14. A vehicle (17) having an electric machine (22) according to any one of claims 10 to 13, the electric machine (22) being configured to drive the vehicle (17).

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