STATOR FOR AN ELECTRIC MOTOR, ELECTRIC MOTOR, AND SPRING ELEMENT FOR A STATOR

Abstract

A stator for an electric motor has a stator main body with stator teeth arranged in the form of a star and a stator yoke. The stator main body is formed with a number of axial grooves on an outer circumference. Spring elements are inserted into the axial grooves and the spring elements circumferentially protrude in the radial direction from the stator main body. The spring elements are introduced with a radial form-fit.

Claims

1. A stator for an electric motor, the stator comprising: a stator main body formed with stator teeth in a star-shaped arrangement and a stator yoke; said stator main body having an external circumference formed with a number of axial grooves; and spring elements inserted with a radial form-fit in said axial grooves and projecting radially on the external circumference of said stator main body.

2. The stator according to claim 1, wherein each of said axial grooves is a radial undercut of the external circumference.

3. The stator according to claim 1, wherein said spring element has a spring main body and at least one first coupler spring projecting in a radial direction and protruding from a respective said axial groove.

4. The stator according to claim 3, wherein said spring main body of said spring element has a narrow side with a second coupler spring that protrudes axially from the respective said axial groove.

5. The stator according to claim 4, wherein said spring element in a region of said second coupler spring has a bearing edge or bearing face by way of which said spring element bears on an end side of said stator main body.

6. The stator according to claim 5, wherein said spring element on a longitudinal side of said main body has at least one clamping claw for tangential fastening in said axial groove.

7. The stator according to claim 3, wherein said spring element on a longitudinal side of said main body has at least one clamping claw for tangential fastening in said axial groove.

8. The stator according to claim 7, wherein said at least one clamping claw is bent upward from a plane of said main body.

9. The stator according to claim 1, wherein said spring element is a one-piece integrally formed stamped bent part.

10. An electric motor, comprising: a motor shaft and a rotor affixed to said shaft; a motor housing; and a stator according to claim 1 disposed in said housing; said stator, with said spring elements inserted in said axial grooves on the external circumference, being held radially with a form-fit in said motor housing.

11. The electric motor according to claim 10, wherein said spring elements are axially inserted into said axial grooves on the external circumference of said stator.

12. A spring element for insertion into an axial groove of a stator, said spring element comprising: a main body having at least one first coupler spring, being a stamped tab incorporated in said main body and bent upward from a plane of said main body, and having a second coupler spring formed on a narrow side of said main body.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0048] FIG. 1 is a perspective illustration showing an electric motor having a motor housing and a bearing bracket;

[0049] FIG. 2 is a perspective illustration of a stator and a rotor of the electric motor;

[0050] FIG. 3 is a sectional illustration showing a portion of the electric motor;

[0051] FIG. 4 is a sectional view showing a portion of a spring element of the stator;

[0052] FIG. 5 is a perspective illustration showing the spring element;

[0053] FIG. 6 is a side view of the spring element; and

[0054] FIG. 7 is a plan view of the spring element.

[0055] Equivalent parts and variables are always provided with the same reference signs throughout the figures.

DETAILED DESCRIPTION OF THE INVENTION

[0056] Referring now to the figures of the drawing in detail and first, in particular, to FIG. 1 thereof, there is shown an electric motor 2 with a motor housing 4 that contains a stator 6 and a rotor 8 (FIG. 2). The electric motor 2 in this exemplary embodiment is configured as an internal rotor electric motor. The rotor 8 is assembled on a motor shaft 10 so as to be fixed on the latter. The motor shaft 10 is rotatably mounted by way of two bearings 12. The bearings 12 in this case may be ball bearings, for example. With reference to FIG. 3, one of the bearings 12 is disposed in a bearing seat 13 of a housing base 14, embodied as a (housing) partition wall, of the motor housing 4. The other bearing 12 is disposed in a bearing bracket 15 which as a cover is placed axially on the can-shaped motor housing 4 so as to be on an end side opposite the housing base 14.

[0057] The stator 6 illustrated in more detail in FIG. 2 and FIG. 3 has a stator main body 16. The stator main body 16 in the exemplary embodiment illustrated is embodied with twelve stator teeth 17 which in the radial direction (R) extend (radially) inward, in the direction of the central rotation axis D illustrated in the drawing. Voids which are not identified in more detail and in which the windings of (stator) coils 18 are received are formed between the stator teeth 17. The windings are connected to one another by way of a wiring ring 19 on the end side, for example in a star connection or delta connection, while forming a stator or rotating field winding. The coils 18 here are disposed on isolating coil bodies 20 which are placed on the stator teeth 17 (FIG. 3). The coils 18 and coil bodies 20 in the figures are provided with reference signs only by way of example. The wiring ring 19 is placed on the end side of the stator main body 16 and fastened in the axial grooves 26 by means of latching tongues 21. The latching tongues 21 here act as positioning or centering cams.

[0058] The stator main body 16 has a stator yoke 22 or back iron which circumferentially encases the stator teeth 17. The stator main body 18 in the exemplary embodiment shown is embodied in the so-called individual tooth design in which the stator 6, or the stator main body 16 thereof, respectively, is assembled from individual stator teeth 17. In an alternative exemplary embodiment, not shown, the stator main body 16 is embodied in a star yoke design in which the stator yoke 22 is a separate component, and wherein the stator teeth 17 form a so-called stator star which is inserted in the stator yoke 22. The stator 6, or the stator main body 16, respectively, or the stator teeth 17 are embodied as solid elements, for example, or are constructed as lamination stacks from individual laminations.

[0059] Axial grooves 26 which run in the axial direction A and extend radially inward toward the rotation axis D are incorporated in the stator main body 16 on the external circumference 24 of the stator yoke 22, that is to say externally circumferentially. The respective axial groove 26 here is in particular embodied as a radial dovetail-shaped or T-shaped undercut of the external circumference 24. A spring element 28 is inserted radially in a form-fitting manner in the respective axial grooves 26. The axial grooves 26 and spring elements 28 are provided with reference signs only by way of example in the figures.

[0060] Viewing the illustrations of FIGS. 4 to 7, the spring element 28 has a strip-shaped or plate-shaped main body 30 on which are integrally molded three first coupler springs or spring arms 32, and one second coupler spring 34 as well as three pairs of clamping claws 36.

[0061] The coupler springs or spring arms 32 hereunder are also referred to as radial springs, and the coupler spring 34 is referred to as an axial spring. The spring element 28 here is embodied in particular as a stamped bent part. The axial spring 34 here is a spring-elastic (spring) tab which is bent to an approximate C-shape or U-shape and is disposed on a narrow side or end side of the substantially rectangular main body 30.

[0062] The spring-elastic radial springs 32 as stamped tabs are formed from the main body 30, and bent from the plane of the main body 30 so as to be approximately C-shaped or U-shaped. To this end, two of the radial springs 32 are disposed in the body of the main body 30 so that two stamped, window-type openings or clearances 38 are formed in the main body 30. The third radial spring 32 is integrally molded on a narrow side or end side of the main body 30 that lies opposite the axial spring 34. The main body 30 protrudes beyond the radial springs 32 in the radial direction R and, at least for the two radial springs 32 stamped out in the interior of the main body 30, also in the axial direction A. In this way, the main body 30 protrudes beyond the radial springs 32 on both sides in the circumferential or tangential direction T, as is comparatively clearly apparent in FIG. 7. The spring element 28, by way of this protrusion 40 on both sides, engages from the rear groove flanks that are formed within the axial groove 26 by virtue of the dovetail shape or T-shape. The protrusion 40 hereunder is also referred to as a connection web or attachment web. In other words, the groove flanks form an undercut for the spring element 28 pushed axially into the axial groove 26.

[0063] As is apparent in particular in FIG. 6, the approximately U-shaped radial springs 32 are bent in such a manner that the horizontal U-leg of the latter has an acute angle of inclination a in relation to the main body 40. The radial springs 32 in the exemplary embodiment shown have an angle of inclination a of approximately 40°, thus in particular 40°±5°. The characteristic of the radial springs 32, thus the ratio between spring force and spring travel, is adjusted by the angle of inclination a. The angle of inclination a here is expediently adapted to the respective application.

[0064] The radial springs 32, or the angles of inclination a, respectively, here are open in the direction of the bearing bracket 15. The spring element 28 in the lateral view (FIG. 6) thus has an approximately fir tree-shaped or sawtooth-shaped geometry. For assembling, the stator 6 is inserted axially into the motor housing 4, wherein the radial springs 42 by way of the free ends thereof slide along the motor housing 4 and in the process are compressed in the direction of the rotation axis D, or in the direction of the main body 30, respectively. The raised radial springs 32 thus also act as introduction aids for positioning the stator 6 in the motor housing 4.

[0065] Three clamping claws or clamping teeth 36 as approximately triangular interlocking cams are in each case integrally molded on the main body 30 of the spring element 28, so as to be on the outside of the protrusions 40 on both longitudinal sides. The clamping claws 36 are bent upward from the plane of the main body 30, in the direction of the raised radial springs 32.

[0066] An approximately U-shaped bending location 42 is provided between the narrow side of the main body 30 and the axial spring 34, said bending location 42 from the plane of the main body 30 first being bent in the direction of the radial springs 32 and subsequently in the direction counter thereto, wherein a vertical U-leg of the bending location 42 here transitions to, or opens into, the approximately U-shaped bend of the axial spring 34. The U-leg 44 here forms a bearing edge or bearing face which from the plane of the main body 40 extends substantially in the radial direction R on the side of the main body 30 that lies opposite the radial springs 32. As is apparent in FIG. 3, for example, and in particular in FIG. 4, the spring element 28, in the assembled state inserted in the respective axial groove 26, by way of this bearing edge or bearing face 44 bears on an end side 46 of the stator main body 16 or the stator yoke 22 of the latter, respectively.

[0067] The axial spring 34 in the assembled state extends axially beyond the axial groove 6 and the end side 36 of the stator main body 16. The axial spring 34 here is in particular disposed on the end side 46 of the stator main body 16 that lies opposite the wiring ring 19. The wiring ring 19 here is disposed in particular so as to face the housing base 14, and the axial springs 34 are disposed in particular so as to face the bearing bracket 15.

[0068] FIG. 3 and FIG. 4 in sectional illustrations show portions of the electric motor 2 in a radial and an axial section plane.

[0069] As is apparent in particular in FIG. 3, the stator 6, by way of the radially raised radial springs 32 of the spring elements 28, which in the radial direction R thus protrude from the stator 6 on the external circumference 24, bears on an internal wall 48 of the motor housing 4. In particular, the radial springs 32 in the region of the free ends or extremities thereof here bear in a resilient or articulated manner on the internal wall 48. In this way, the stator 6 is decoupled from the motor housing 4 of the, for example, 10-pole electric motor 2.

[0070] Furthermore, the stator 6 on the end side, by way of the axial springs 34 of the spring elements 28, bears on the bearing bracket 15 and is thus also decoupled in relation to the latter (FIG. 4). The axial springs 34 here, by means of the bearing edges or bearing faces 44, are supported on the end side 46 and at a free end are compressed or bent toward the bearing bracket 15 on an edge of a spring installation space 50. The transmission of the structure-borne noise, which is caused for example by the operationally caused electromagnetic forces, to the motor housing 4 and the bearing bracket 15 is reduced as a result in that the stator 6 by means of the spring elements 28 is decoupled from the motor housing 4 and optionally from the bearing bracket 15. The spring elements 28 here preferably also have damping, fixing and/or positioning properties. An anti-rotation safeguard of the stator 6 in the motor housing 4 is in particular implemented by the spring elements 28 bearing on the internal wall 48 and the bearing bracket 15.

[0071] The spring elements 28 can be inserted in the axial direction A into the axial grooves 26 in an automated and particularly simple manner. Moreover, the spring elements 28 are held radially in a form-fitting and thus reliable manner within the axial grooves 26. Furthermore, even further fixing of the spring elements 28 as a result of the azimuthally raised and radially slightly bent clamping claws 36 is implemented. Form-fitting and/or force-fitting fixing in the tangential and axial direction of the axial grooves 26 is implemented in particular here.

[0072] The invention is not limited to the exemplary embodiment described above. Rather, other points of the invention may also be derived therefrom by the person skilled in the art without departing from the subject matter of the invention. Furthermore, individual features described in the context of the exemplary embodiment may in particular be combined with one another in a different way without departing from the subject matter of the invention.

[0073] The electric motor 2 shown in the exemplary embodiment is in particular a steering motor of a motor vehicle. The solution described above may be used not only in the specially illustrated application but in a similar embodiment also in other automotive applications such as, for example, in electric brake motors, door and tailgate systems, power windows, as well as in electric drives and the disposal of the latter in the vehicle, or in other electric machines and systems.

[0074] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0075] 2 Electric motor [0076] 4 Motor housing [0077] 6 Stator [0078] 8 Rotor [0079] 10 Motor shaft [0080] 12 Bearing [0081] 13 Bearing seat [0082] 14 Housing base [0083] 15 Bearing bracket [0084] 16 Stator main body [0085] 17 Stator tooth [0086] 18 Coil [0087] 20 Coil body [0088] 21 Latching tongue [0089] 22 Stator yoke [0090] 24 External circumference [0091] 26 Axial groove [0092] 28 Spring element [0093] 30 Main body [0094] 32 Coupler spring/radial spring [0095] 34 Coupler spring/axial spring [0096] 36 Clamping claw [0097] 38 Clearance [0098] 40 Protrusion [0099] 42 Bending location [0100] 44 U-leg/bearing edge/bearing face [0101] 46 End side [0102] 48 Internal wall [0103] 50 Spring installation space [0104] A Axial direction [0105] R Radial direction [0106] T Tangential direction [0107] D Rotation axis