Stator for an electrical machine having a resilient outer contour

Abstract

A stator lamination (110) for a stator (100) of a rotating electrical machine (200) is described. The stator lamination (110) comprises a yoke region (111), which has a radially inner edge (1110) and a radially outer edge (1111). In an outer region of the yoke region (111), a plurality of first cutouts (1112) is provided along the radially outer edge (1111). A first cutout (1112) comprises a radially outer boundary (1116) having a curvature in the same direction as the radially outer edge (1111), and, between the first cutouts (1112) and the radially outer edge (1111), ridges (1114) are formed, which, for interaction with a mounting surface (113a) of a stator housing (113), are elastically deformable in the radial direction and produce a spring action.

Description

[0001] ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 Stator for an electric machine with a resilient outer contour The invention relates to a stator lamination for a stator of a rotating electric machine and further to a stator, an electric machine and a motor vehicle equipped therewith. The use of electric drives in motor vehicles is currently increasing rapidly, be it as a hybrid drive in combination with a combustion engine or as a purely electric drive. Such electric machines usually have a rotor and a stator, whereby in an internal rotor machine the stator is arranged within a housing that encloses it on the outside and is supported by it. To achieve a weight advantage, these machine housings are usually made of an aluminum material. A force reaction acting between the stator and the housing during operation of the machine, i.e. a supporting force orA support torque is essentially based on transverse pressure between the connecting parts and is highly temperature-dependent. The usable temperature range for safe operation of the electrical machine is therefore comparatively narrow. On the other hand, however, motor vehicles should be designed so that they can be used reliably within a comparatively wide temperature range. The temperature range extends from -40°C to +85°C, and increasingly also between -45°C and +90°C. Compared to the upper temperature limit, the force reaction at the lower temperature limit can be three times higher. At the lower temperature limit, the housing can deform as a result, and at the upper temperature limit, the machine stator cannot generate the required support torque and twists relative to the housing, i.e., slips.To reliably transmit torque under all operating conditions, very large overlaps are required between the stator's steel laminated core and the housing. The large overlap between the stator and housing and the different thermal expansion coefficients generate high mechanical stresses in the components. During assembly, the housing must be heated considerably. There is a risk of seizure. The rigid coupling between the stator and housing created by the transverse interference fit also promotes the transmission of vibration and noise from the electric motor to the drive unit. ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 The goal is to provide a solution that can reduce the aforementioned force response change within the common temperature range or increase the temperature range in which the electric motor can be operated.This is achieved by a stator lamination according to the invention, a stator according to the invention, a corresponding electrical machine and a corresponding motor vehicle. A stator lamination for a stator of a rotating electrical machine is proposed, which has: - a yoke region with a radially inner edge and a radially outer edge and wherein - in an outer region of the yoke region along the radially outer edge, a plurality of first recesses are arranged, wherein - the first recesses have a radially outer boundary with a curvature that is directed in the same direction as the radially outer edge and wherein webs are formed between the first recesses and the radially outer edge, which webs are elastically deformable in the radial direction for cooperation with a mounting surface of a stator housing and develop a spring effect.An electrical machine within the meaning of the invention can be a generator for electrical energy, as well as an electric drive that converts electrical energy into rotational energy, for example to drive a motor vehicle. In particular, an electrical machine within the meaning of the invention has an internal rotor and an external stator. Recesses within the meaning of the invention can be holes, punched out sections, bores and the like in the stator lamination. The webs of the stator laminations, which are spring-elastic in the radial direction, are clamped during installation in a stator housing. As a result, a spring force that is distributed radially and essentially evenly along the circumference acts between the stator laminations or a stator manufactured therewith and the stator housing. ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27.This spring force acts across the entire operating temperature range and can at least partially compensate for a decreasing mutual contact force that occurs due to the different thermal expansion of the stator laminated core and stator housing. This has the advantage that the temperature dependence of the supporting force or the force reaction of the stator during operation of the electrical machine can be reduced. In other words, the characteristic curve of the force reaction in relation to temperature can be flatter. In particular, a radial component of the supporting force is advantageously influenced. As a result, the machine can therefore be operated safely over a wider temperature range and a wider torque range. A stator lamination in the sense of the invention means a thin, circular disk made of an electrical steel sheet, which can be formed in one piece or in multiple pieces.If a large number of such stator laminations are axially stacked along a stator central axis or the axis of symmetry of the machine, an annular stator laminated core is produced. The stator laminated core is intended for installation in a stator housing. Advantageously, in the proposed stator lamination, the radially outer edge can be designed, in particular with a continuously running contour, in a wave-shaped, for example sinusoidal, wherein an outer recess or an outer recess is formed in the circumferential direction between two first recesses. In this way, arc-shaped, in particular convex-shaped webs are produced with an effective length that is greater than the outer circular edge of the stator lamination. This means that the deformation range of the stator lamination that is effective relative to a stator housing is thereby increased.In particular, due to the large number of deformable webs on the circumference, an effective total length of the webs can exceed the circumferential length of the stator lamination. To achieve a softness or elasticity that is distributed as evenly as possible in the circumferential direction, the webs can have a substantially constant width in the region of the extension of the first recesses. ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 An even further improvement in the support behavior of a stator lamination in the installed state can be achieved by providing second recesses radially inside the first recesses in the outer region of the yoke region, wherein elastically deformable webs are formed between the first recesses and the second recesses. A further aspect of the invention relates to a stator for an electrical machine having a large number of stacked stator laminations according to the invention.For an even distribution of the spring force generated by the webs in a stator housing, a stator lamination can be arranged circumferentially offset from an axially adjacent stator lamination within the stator laminated core. The stator can consist of packages of stator laminations that are rotated relative to one another in the circumferential direction and do not overlap, although the stator laminations within a package can be stacked congruently. With particular regard to the use of the stator as a power source for a vehicle, a stator housing and the stator laminated core are dimensioned and joined to one another in such a way that the webs of the stator laminations resting against the stator housing are elastically braced relative to the stator housing within the entire operating temperature range, in particular between -45°C and +90°C.Thus, a sufficiently high supporting force for the reaction torque of the electric machine can be provided across the entire intended area of ​​use. Yet another aspect of the invention relates to an electric machine with a stator according to the invention. Furthermore, the invention also relates to a motor vehicle with an electric machine according to the invention. This has the advantage that a motor vehicle can be provided in which the electric machine can be operated more safely and efficiently within the specified operating temperature range and / or the operating temperature range of the motor vehicle can be increased. ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 Further advantages will become apparent from the following description, the figures, and the patent claims. Attached exemplary figures are described below. They show: Fig. 1a an embodiment of a stator lamination according to the invention; Fig.1b shows a further exemplary embodiment of a stator lamination according to the invention; Fig. 2 shows a further exemplary embodiment of a stator lamination according to the invention; Fig. 3 shows a further exemplary embodiment of a stator lamination according to the invention; Fig. 4 shows an exemplary embodiment of a stator according to the invention; and Figs. 5a, b show two views of an electrical machine with a stator according to the invention. Figs. 1a, b show exemplary embodiments of a stator lamination 110 according to the invention, in particular a circular ring-shaped stator lamination, which is, however, only shown in detail. Alternatively, a stator lamination 110 can also be formed from a plurality of joined circular ring segments. The metallic stator lamination 110 has a yoke region 111a and a tooth region 111b with a plurality of stator teeth which protrude radially inward from the yoke region 111a. The stator lamination 110 has a radially inner edge 1110 and a radially outer edge 1111.The radially outer edge 1111 is larger than the radially inner edge 1110. The radially outer edge 1111 is intended for interaction with a cylindrical inner circumferential surface of a housing of an electrical machine. Furthermore, the stator lamination 110 has a plurality of first recesses 1112 in the yoke region 111a. The recesses 1112 are arranged at equal spacings in an outer region of the yoke region 111a and along the radially outer edge 1111. A first recess 1112 has a radially outer boundary 1116 with a curvature aligned with the radially outer edge 1111. Radially between the recesses 1112 and the radially outer edge 1111, webs 1114 are formed, which are at least partially elastic and deformable in particular in the radial direction. ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27Due to their geometric structure, the webs 1114 are suitable for exerting a spring effect, preferably on the radially outer edge of the stator lamination 110. On the radially outer circumference 1111 of the stator lamination 110, the press diameter is interrupted by external recesses 1111a, so that here it only consists of arc-shaped, in particular convex-shaped webs 1114. These external recesses on the radially outer circumference 1111 can be optional. The outer circumference 1111 can alternatively also be designed as a circular line. The large number of recesses 1112 and associated webs 1114 create a radial softness that acts uniformly around the circumference, which on the one hand facilitates the assembly of the stator in the machine housing and on the other hand ensures the reliable torque support of the stator over a wider operating temperature range. In Fig.1a, the first recesses 1112a are elliptical in shape, with the larger main axis of an ellipse aligned in the circumferential direction of a stator lamination. Alternatively, a circular shape is also possible. In Fig. 1b, the first recesses 1112b are arcuate or kidney-shaped. In both embodiments, the webs 1114 have a substantially constant radial extent or width in the region of the extension of the first recesses 1112a, b. Fig. 2 shows a further embodiment of a stator lamination 110 according to the invention, which in turn is only shown in detail. In the stator lamination of Fig. 2, the first recesses 1112c have an arcuate portion formed in the circumferential direction and two substantially straight portions pointing in the radial direction. The recesses 1112c are thus approximately U-shaped overall.The webs 1114 formed on the circumference accordingly have a section 1114a formed in the circumferential direction and two essentially radially extending sections 1114b. A radially inner boundary 1115 of the recesses 1112c is wave-shaped, so that the web section 1114a can come into contact there if deformed. ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 The first recesses 1112 shown in Figs. 1a, b; 2 can have a larger circumference / area ratio than an elliptical shape, so that a better spring effect for support in a machine housing can be achieved by the webs 1114 adjacent there. Fig. 3 shows a further exemplary embodiment of a stator lamination 110 according to the invention, which is fundamentally based on that of Fig. 2. The stator lamination 110 has a plurality of further, second recesses 1113 in the yoke region 111.The recesses 1113 are evenly spaced in the yoke region 111, in an outer region of the yoke region 111, radially within the plurality of recesses 1112c. The recesses 1113 are, for example, circular in shape and thus have at least one rounding. The recesses 1113 are delimited in the circumferential direction and radially outward by, in particular, elastically deformable webs 1117, which further increase the spring action already explained. The plurality of second recesses 1113 is divided into recess sets 120. A recess set 120 has at least two second recesses 1113. Preferably, a center of a longitudinal axis of a recess set is arranged perpendicular to a center of a longitudinal side of a corresponding recess 1112 of the plurality of recesses 1112c.Furthermore, on a side of a recess set 120 facing the corresponding recess 1112c, the yoke region 111 is again designed in a wave-shaped manner, following the surface of the respective second recesses 1113 of the recess set 120 and protruding into the respective recess 1112c. Fig. 4 shows an embodiment of a stator 100 according to the invention. The stator 100 has a plurality of stator laminations 110 according to the invention, which are stacked along a central axis of the stator 100 and form a stator laminated core 130. In the example of Fig. 4, these are stator laminations 110 as shown in Fig. 3. The stator laminations 110 form a transverse interference fit. By means of the radial spring effects of a stator lamination 110, the negative effects of thermal expansion on the transverse interference fit can be positively influenced.The stator laminations 110 are arranged one after the other along the stator axis, thus forming the transverse interference fit. Within the stator core (130), a stator lamination (110) is circumferentially offset from an axially adjacent stator lamination (110), i.e., the stator laminations (110) are arranged without achieving congruent alignment with one another. In particular, in this specific embodiment, a stator lamination 110 is arranged offset from the respectively adjacent stator lamination 110 by an integer plurality of a length of a second recess 1113 of a recess set 120, such that a recess 1112 of a stator lamination 110 contacts two first recesses 1112 of a respectively adjacent stator lamination 110.In this case, a second recess 1113 of a stator lamination 110 is arranged offset from a second recess 1113 of the respectively adjacent stator lamination 110, such that a second recess 1113 of a stator lamination 110 only partially overlaps with a second recess 1113 of the respectively adjacent stator lamination 110. Furthermore, a closing element 112 can be provided, which covers an outer stator lamination 110. Fig. 5 shows an embodiment of an electrical machine 200 according to the invention. Fig. 5a shows the electrical machine 200 in a cross-section, and Fig. 5b shows it in longitudinal section. Only the stator 100 and the housing 113 are shown. The stator in Fig.5 has a cylindrical stator housing 113 with an inner mounting surface 113a for arranging the stator 100.In this case, a stator lamination 110 contacts the stator housing 113 essentially only perpendicularly along a transverse axis of the center of the longitudinal side of the corresponding recess 1112 of the plurality of recesses 1112. The deformation occurring during installation of the stator 100 in the stator housing 1113 with respect to the webs 1114 of the stator laminations 110, explained in FIGS. 1-3, compensates for the greater thermal expansion of the aluminum housing. ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 Furthermore, partial vibration decoupling between the transverse interference fit and the housing can be created. The axial channels of the stator 100 created by the recesses 1112 simultaneously serve as cooling channels in fluid-cooled electrical machines 200.There are basically two designs to distinguish between the size and shape of the recesses 1112: In a first design, the smallest radial enveloping circle diameter resulting from a recess 1112 is greater than or equal to the press diameter of the stator housing 113. This results in better thermal connection between the stator 100 and the housing 113, since after assembly the stator 100 rests almost completely against the housing bore. In a second design, the smallest radial enveloping circle diameter resulting from the recess 1112 is smaller than the press diameter of the stator housing 113. This creates additional cooling channels, a poorer direct thermal connection, but better vibration decoupling. For better cooling design and to increase the supporting force of the stator 100 in the stator housing 113, further, second recesses 1113 can be introduced radially inside the first recesses 1112.It is advantageous if the additional inner row of cooling passages is arranged opposite the first valley-forming recess 1112. The arc structures can be distributed over the circumference and have different geometric designs. It is advantageous if, in fluid-cooled electrical machines 200, the pitch of the arc elements is a multiple of the punch-induced lamination rotation. If, in certain designs of the electrical machine 200, the axial fluid flow through the outer region of the stator 100 is to be throttled or prevented, this can be achieved by an irregular multiple of the arc pitch of the punch-induced lamination rotation. ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 Another solution for this is to close the axial channels with an unperforated end plate or with elastomeric sealing plugs.In order to be able to visually monitor the correct sheet rotation during the assembly process, one or more arch elements can be designed asymmetrically or marked with notches.

[0002] ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 Reference numeral 100 Stator 110 Stator lamination 111a Yoke area 111b Tooth area 112 End element 113 Stator housing 113a Mounting surface 200 Electric machine 1110 Radial inner edge 1111 Radial outer edge 1111a Outer recess 1112 First recess 1112a Recess 1112b Recess 1112c Recess 1113 Second recess 1114 Web 1114a Web section 1114b Web section 1115 Inner boundary 1116 Outer boundary 1117 Web 120 Set 130 Stator laminated core 140 Outer boundary of a recess 150 Stator center axis

Claims

ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 Patent claims 1. Stator lamination (110) for a stator (100) of a rotating electrical machine (200), wherein the stator lamination (110) comprises: - a yoke region (111) with a radially inner edge (1110) and a radially outer edge (1111), and wherein - in an outer region of the yoke region (111) along the radially outer edge (1111) a plurality of first recesses (1112) are arranged, wherein - a first recess (1112) has a radially outer boundary (1116) with a curvature directed in the same direction as the radially outer edge (1111), and wherein webs (1114) are formed between the first recesses (1112) and the radially outer edge (1111), which webs are Interaction with a mounting surface (113a) of a stator housing (113) is elastically deformable in the radial direction and develops a spring effect. 2.Stator lamination (110) according to claim 1, characterized in that the radially outer edge (1111) is wave-shaped and that an outer recess (1111a) is formed in the circumferential direction between each two first recesses (1112).

3. Stator lamination (110) according to claim 1 or 2, characterized in that the webs (1114) have a substantially constant width in the region of the extension of the first recesses (1112).

4. Stator lamination (110) according to one of claims 1-3, characterized in that second recesses (1113) are provided in the outer region of the yoke region (111) radially inside the first recesses (1112), wherein elastically deformable webs (1117) are formed between the first recesses (1112) and the second recesses (1113).

5. Stator (100) for an electrical machine comprising a plurality of stator laminations (110) according to one of the preceding claims, which are arranged along a. ZF Friedrichshafen AG File 211719 Friedrichshafen 2022-06-27 are axially stacked along the stator center axis (150) and form a stator laminated core (130).

6. Stator (100) according to claim 5, characterized in that within the stator laminated core (130), a stator lamination (110) is arranged offset in the circumferential direction from an axially adjacent stator lamination (110), i.e., they are arranged without achieving congruence with one another.

7. Stator (100) according to claim 5 or 6, further comprising a stator housing (113), wherein the stator laminated core (130) is joined to the stator housing (113) such that the webs (1114) of the stator laminations (110) resting against the stator housing (113) are elastically braced relative to the stator housing (113) within the entire operating temperature range, in particular between -45°C and +90°C.

8. Electrical machine (200) comprising a stator (100) according to one of claims 5 to 7. 9.Motor vehicle comprising an electric machine (200) according to claim 8.

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