STATOR ASSEMBLY FOR AN ELECTRIC MACHINE

Abstract

A stator assembly (1) for an electric machine is provided, the stator assembly (1) comprising a stator housing (20) and a stator lamination stack (10) which is received in the stator housing (20). The stator lamination stack (10) has at least two outer partial lamination stacks (12, 13) and a central partial lamination stack (11) which is arranged in the axial direction (R) of the stator lamination stack (10) between the at least two outer partial lamination stacks (12, 13). The central partial lamination stack (11) and the at least two outer partial lamination stacks (12, 13) have different outer diameters.

Description

The present disclosure relates to a stator assembly for an electric machine, a stator including the stator assembly, an electric machine including the stator assembly, and / or a motor vehicle including the electric machine.Electric machines which can be used in motor vehicles, for example as traction machines, each have a rotor and a stator surrounding the rotor. By electrically applying electrical windings or conductors of the stator and / or rotor, a magnetic interaction is generated between the stator and the rotor and a mechanical energy is provided, which can be tapped via the rotation of the rotor and used, for example, for driving the electrically drivable motor vehicle or another machine in the motor vehicle.The stator usually comprises a stator laminated core which is arranged in a housing, for example, by means of a thermal cross-press fit, wherein only one diameter is designed as a joining diameter or a constant overdimension along the axial length of the cross-press fit.When using a single constant joining diameter and a single constant overdimension, high mechanical loads occur in the joining partners, in particular at the transitions (or ends and / or boundaries) (as seen in the axial direction) from the joining region to the non-joining region, above all at the currently wide temperature application range from -60° C. to 200° C. This can lead to local failure of the components or the components have to be designed accordingly, which often leads to a marked increase in weight on the mechanical side or to a reduction in the electromagnetic performance of the electric machine.JP 2011-152041 A describes a stator fixed to a housing of a rotating machine by shrink or press fitting, wherein the stator is disposed around a stator core formed by laminating a plurality of electromagnetic steel plates having different outer diameters, and wherein the stator has an outer circumferential shape tapered in the axial direction.DE 10 2018 005 142 A1 describes a rotor comprising a rotating element, a plurality of permanent magnets arranged on the outer periphery of the rotating element, and a cover tube mounted on the outer periphery of the permanent magnets so as to cover the permanent magnets and formed of fiber-reinforced plastic. At least one of the rotating element and / or the permanent magnets has an expanding diameter portion having an expanding diameter peripheral surface. The expanding diameter portion has a diameter that increases from a region having a first diameter to a region having a second diameter. The region with the first diameter has a diameter which corresponds to an inner diameter of the cladding tube or is less than the latter. The second diameter portion has a diameter that matches or is larger than an outer diameter of the permanent magnets.WO 2020 / 184057 A1 describes a stator of a motor comprising an inner core having a plurality of protrusions extending radially outward from the outer circumferential surface of a cylindrical cylinder part and a cylindrical outer core having an inner circumferential surface into which the tips of the protrusions of the inner core are press-fitted. Further, in the tip of each protrusion of the inner core, at least one through hole is formed extending from one axial surface of the inner core to the other.Against the background of this prior art, the object of the present disclosure is to specify an apparatus and / or a method which are each suitable for improving the prior art.The object is achieved by the features of the independent claims. The subordinate claims and the dependent claims each have optional developments of the disclosure.The object is then achieved by a stator assembly for an electric machine.The stator assembly includes a stator housing.The stator assembly comprises a stator laminated core which is accommodated in the stator housing. The stator laminated core has at least two outer laminated sub-cores and a middle laminated sub-core which is arranged between the at least two outer laminated sub-cores in the axial direction (and / or in the longitudinal direction) of the stator laminated core.The middle partial laminated core and the at least two outer partial laminated cores have different outer diameters.The stator assembly described above provides a number of advantages. Thus, among other things, the mechanical loads or stresses in the stator housing and in the stator laminated core, which arise, for example, in a thermal cross-press fit, are advantageously reduced. Thus, it is possible, inter alia, to make possible new designs of electrical machines and of housings which are easier and more efficient, and also more scalable to manufacture and can therefore be produced more cost-effectively.Possible refinements of the stator assembly described above are explained in detail below.The different outer diameters can decrease steadily, for example in a step-like manner, in the axial direction. Alternatively, it is conceivable that the at least two outer partial laminated cores have, for example, identical outer diameters which can be smaller than an outer diameter of the middle partial laminated core.The middle partial laminated core and the at least two outer partial laminated cores can each have constant outer diameters.The central partial laminated core can have a greater length in the axial direction than each of the at least two outer partial laminated cores.Different (e.g. effective) oversizes can be formed between the stator housing and the stator laminated core. A larger (e.g. effective) overdimension can be formed between the stator housing and the middle partial laminated core than between the stator housing and the at least two outer partial laminated cores. As a result, the mechanical stresses can be further reduced in an advantageous manner.The stator lamination stack may have a wedge structure that may be formed on an outer surface of the stator lamination stack and may extend in the axial direction. The stator housing may include a groove that may be formed on an inner surface of the stator housing to receive the wedge structure and may extend in the axial direction. The wedge structure and the groove for receiving the wedge structure advantageously allow the oversize in the critical regions to be further reduced. This advantageously also ensures that the maximum torque can be transmitted reliably even at the highest temperatures.The middle partial laminated core and the at least two outer partial laminated cores can have the same inner diameter and / or a same inner surface structure. The inner surface structure may have uniformly distributed teeth and / or longitudinal grooves or be formed by these, wherein the teeth and / or longitudinal grooves may extend in the axial direction. Electrical windings or conductors can be arranged on and / or between the teeth and / or longitudinal grooves.The stator housing and the stator laminated core can be joined by means of a thermal transverse press fit.The stator housing may be made at least partially of an aluminum alloy, e.g., a cast aluminum alloy. The stator laminated core can be produced at least partially from a silicon and / or iron alloy.The stator laminated core can be designed in the form of a circular hollow cylinder. The middle partial laminated core and the at least two outer partial laminated cores can be designed in the form of a circular hollow cylinder. The middle partial laminated core and the at least two outer partial laminated cores can be arranged one behind the other in the axial direction and coaxially with respect to one another.The stator housing can be designed in the shape of a pot with a circular basic shape (and / or in the shape of a circular hollow cylinder). A first end of the stator housing can be designed open (for receiving the stator laminated core in the stator housing). The first end may include an outer collar. A second end of the stator housing opposite the first end can have a (e.g. central) opening for receiving the rotor shaft.The stator laminated core and the stator housing can expediently be arranged coaxially with respect to one another.The above description can be summarized in other words and on a possible more specific configuration of the disclosure as described below, wherein the following description is to be interpreted as not restrictive for the disclosure.Very high mechanical loads can occur at the end regions of a joint assembly as a function of a temperature application region, a mechanical production (tolerances) and jumps in rigidity. In order to reduce the loads, an (assembly) laminated core can be divided into at least three partial laminated cores, which can differ in that their outer diameters differ, but the remaining geometry (sheet-metal section) remains unchanged in order not to adversely affect the process of the stator winding.It can be provided that the central region is the axially largest region and is also the region which has the greatest effective oversize between the stator or laminated core and the housing. The two subsequent partial laminated cores of the stator can have a different diameter and a different effective overdimension from the central region. The effective excess in these regions may advantageously be smaller than the effective excess of the middle region in order to reduce the stresses.Depending on the housing design, the stator laminated cores adjoining the central region can be designed identically (housing divided in the central region) or the stator laminated cores can have a staircase-shaped diameter variation along the axial length of the stator or of the laminated core in order to realize changed diameter lines or regions and to enable a defined or one-sided mounting of the stator.In order to be able to further reduce the oversize in the critical regions, a wedge structure can be introduced into the stator laminated cores and a corresponding mating contour can be introduced as a groove in the housing. It can thus be ensured that at the highest temperatures in a worst-case scenario, the maximum torque can be transmitted reliably. The housing may be made of a cast alloy of aluminum and the stator lamination stacks may be made of a silicon-iron alloy, wherein the thermal expansion coefficient of aluminum is greater than the thermal expansion coefficient of a silicon-iron alloy.Further provided is a stator for an electric machine comprising the stator assembly described above.The stator can have electrical windings (or conductors) which can be supplied with an alternating current and / or three-phase current, for example, in order to drive the rotor.The description above with reference to the stator assembly applies analogously also to the stator and vice versa.Furthermore, an electric machine (for a motor vehicle) is provided, which comprises the stator assembly described above and / or the stator described above.The electric machine can comprise a rotor, wherein the stator can surround the rotor at least on the circumference or in the circumferential direction.The rotor may include a rotor shaft. The rotor can have a laminated rotor core which can surround the rotor shaft. The rotor shaft can be accommodated in a central opening of the laminated rotor core.The description above with respect to the stator assembly and the rotor applies analogously also to the electric machine and vice versa.Furthermore, a motor vehicle is provided which comprises the above-described electric machine.The motor vehicle can be an electrically drivable motor vehicle. The electric machine can be designed as a traction motor or traction machine of the motor vehicle.The motor vehicle may comprise an electrical source, e.g. a traction battery, for supplying the stator (e.g. electrical windings or conductors of the stator) with electrical energy and / or with an alternating current via at least one converter.The motor vehicle can be a passenger car, in particular an automobile, or a commercial vehicle, such as a truck.The description above with reference to the stator assembly, the rotor and the electric machine applies analogously also to the motor vehicle and vice versa.An optional embodiment will be described below with reference to FIGS. 1 to 4. FIG. 1 schematically shows a sectional view of a stator assembly according to the disclosure in a joined state, FIG. 2 schematically shows an exploded view of the stator assembly or an oblique view of the stator assembly in an joined state, FIG. 3 schematically shows an oblique view of a stator laminated core of the stator assembly, and FIG. 4 schematically shows an oblique view of a stator housing of the stator assembly.The stator assembly 1 shown merely schematically in a sectional view in FIG. 1 comprises a stator housing 20 and a stator laminated core 10, wherein the stator housing 20 and the stator laminated core 10 can be joined, for example, by means of a thermal transverse compression bond.The stator laminated core 10 is accommodated in the stator housing 20 and has two outer laminated sub-cores 12, 13 and a central laminated sub-core 11 which is arranged between the two outer laminated sub-cores 12, 13 in the axial direction R of the stator laminated core 10. It is conceivable that the stator laminated core 10 can have further, for example outer, stator laminated cores.The stator laminated core 10 is distinguished inter alia in that the central laminated sub-core 11 and the two outer laminated sub-cores 12, 13 have different outer diameters.The different outer diameters may steadily decrease in the axial direction R. As can be seen in FIG. 1, the different outer diameters can become smaller in the axial direction in a stepwise manner, wherein the middle laminated sub-core 11 has a smaller outer diameter than the outer laminated sub-core 12 and the outer laminated sub-core 13 in turn has a smaller outer diameter than the middle laminated sub-core 11.The middle laminated sub-core 11 represents the largest portion of the stator laminated core 10, i.e. it has a greater length in the axial direction R than each of the two outer laminated sub-cores 12, 13.It is also conceivable that different (e.g. effective) oversizes are formed between the stator housing 20 and the stator laminated core 10, wherein a larger (e.g. effective) oversize is formed between the stator housing 20 and the middle laminated core section 11 than between the stator housing 20 and the two outer laminated core sections 12, 13.The stator housing 20 can be (at least partially) made of an aluminum alloy. The stator laminated core 10 can be (at least partially) produced from a silicon and / or iron alloy.Further optional details are shown in FIGS. 2 to 4. Thus, FIG. 2 shows the stator assembly 1 in a non-joined state, i.e. in a separated state of the stator laminated core 10 and of the stator housing 20.Thus, the stator laminated core 10 is designed in the form of a circular hollow cylinder, wherein the laminated sub-cores 11, 12 and 13 are arranged coaxially one behind the other in the axial direction R.The inner surface of the stator laminated core 10 is configured identically over the entire surface, i.e. the middle laminated core 11 and the two outer laminated cores 12, 13 have the same inner diameter and / or an identical inner surface structure 15. The inner surface structure 15 can be uniformly distributed teeth, on or between which electrical windings or conductors can be arranged.The stator housing 20 is configured in the shape of a pot with a circular basic shape. A first end of the stator housing 20 is designed open for receiving the stator laminated core 10 into the stator housing 20, wherein the first end has an outer collar 25. A second end of the stator housing 20 opposite the first end has an opening 26 for receiving the rotor shaft.The stator housing 20 can have a plurality of housing sections with different inner diameters, for example to form the different oversizes. For example, the stator housing 20 may have two outer housing sections 22, 23 and a middle housing section 21 arranged between the two outer housing sections 22, 23. In the assembled state of the stator assembly 1, the middle housing section 21 can surround the middle laminated sub-core 11 and the two outer housing sections 22, 23 can surround the two outer laminated sub-cores 12, 13 on the circumferential side.In the assembled or joined state of the stator assembly 1, the stator laminated core 10 and the stator housing 20 are expediently arranged coaxially with respect to one another.The stator laminated core 10 may further include a wedge structure 14 formed on an outer surface of the stator laminated core 10 and extending in the axial direction R. The stator housing 20 may include a groove 24 formed on an inner surface of the stator housing 20 and extending in the axial direction R to receive the spline structure 14. During assembly, the wedge structure 14 can be correspondingly accommodated in the groove 24 and can be pushed into the stator housing 20 until the entire stator laminated core 10 is arranged within the stator housing 20.The stator assembly 1, e.g. according to the embodiment described above, can be part of a stator, wherein the stator can further comprise, inter alia, electrical windings or conductors which can be supplied with an alternating current or three-phase current.The stator can form together with a rotor, which can be passed centrally through the stator assembly 1, an electric machine, which can be installed, for example, as a drive machine in a motor vehicle.List of reference characters1 Stator assembly 10 Stator laminated core 11 Central laminated core part 12, 13 Outer laminated core parts 14 Wedge structure 15 Inner surface structure of the stator laminated core 20 Stator housing 21 Central housing section 22, 23 Outer housing sections 24 Groove 25 Outer collar 26 Opening for receiving the rotor shaftReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2011-152041 A

[0005] DE 10 2018 005 142 A1

[0006] WO 2020 / 184057 A1

[0007]

Claims

Stator assembly (1) for an electric machine, wherein the stator assembly (1) comprises: - a stator housing (20), and - a stator laminated core (10) which is accommodated in the stator housing (20), wherein the stator laminated core (10) has at least two outer laminated sub-cores (12, 13) and a middle laminated sub-core (11) which is arranged between the at least two outer laminated sub-cores (12, 13) in the axial direction (R) of the stator laminated core (10), characterized in that - the middle laminated sub-core (11) and the at least two outer laminated sub-cores (12, 13) have different outer diameters.Stator assembly (1) according to Claim 1, characterized in that the different outer diameters continuously decrease in the axial direction (R).Stator assembly (1) according to Claim 1 or 2, characterized in that the central laminated sub-core (11) has a greater length in the axial direction (R) than each of the at least two outer laminated sub-cores (12, 13).Stator assembly (1) according to one of Claims 1 to 3, characterized in that different oversizes are formed between the stator housing (20) and the stator laminated core (10), wherein a larger oversize is formed between the stator housing (20) and the middle laminated core part (11) than between the stator housing (20) and the at least two outer laminated core parts (12, 13).Stator assembly (1) according to one of Claims 1 to 4, characterized in that - the stator laminated core (10) has a wedge structure (14) which is formed on an outer surface of the stator laminated core (10) and extends in the axial direction (R), and - the stator housing (20) has a groove (24) which is formed for receiving the wedge structure (14) on an inner surface of the stator housing (20) and extends in the axial direction (R).Stator assembly (1) according to one of Claims 1 to 5, characterized in that the central laminated sub-core (11) and the at least two outer laminated sub-cores (12, 13) have the same inner diameter and / or an identical inner surface structure (15).Stator assembly (1) according to one of Claims 1 to 6, characterized in that the stator housing (20) and the stator laminated core (10) are joined by means of a thermal transverse compression bond.Stator assembly (1) according to one of Claims 1 to 7, characterized in that the stator housing (20) is produced at least partially from an aluminium alloy and / or the stator laminated core (10) is produced at least partially from a silicon and / or iron alloy.Electric machine, characterized in that the electric machine comprises the stator assembly (1) according to one of claims 1 to 8.Motor vehicle, characterized in that the motor vehicle comprises the electric machine according to Claim 9.

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