Stator laminate and laminated stator core

Abstract

A stator lamination for a laminated stator core of a brushless DC motor, the stator lamination being fully closed in the circumferential direction and having a plurality of star elements, two adjacent star elements being connected to each other in each case by a bridge, the bridge being narrowed in the radial direction by means of at least one groove.

Description

Technical Field

[0001] The invention relates to a stator lamination for a laminated stator core of a brushless DC motor. The stator lamination is completely closed in the circumferential direction and has a plurality of star elements, wherein two adjacent star elements are in each case connected to one another via a bridge. Background Art

[0002] Stator laminations of the type mentioned at the outset are known in principle from the prior art. EP 2507 896 B1 discloses a method for producing a stator for an electric motor, wherein a plurality of stator laminations are stacked to form a star-shaped laminated core, which consists of stator laminations which are closed in the circumferential direction and have single teeth connected to one another by pole shoe connecting bars and stator laminations which are open in the circumferential direction and have single teeth which are spaced apart on the pole shoe side to form gaps. Summary of the invention

[0003] The object of the present invention is to specify a stator lamination which provides the basis for a laminated stator core which can be produced in a relatively simple and cost-effective manner.

[0004] This object is achieved in that the bridge is narrowed in the radial direction by means of at least one groove. It has proven to be advantageous if the groove extends in the axial direction over the entire thickness of the stator core.

[0005] The present invention incorporates the following insight: In the prior art, in order to achieve certain magnetic properties, a laminated stator core must have different types of stator laminations, i.e., stator laminations that are closed in the circumferential direction and stator laminations that are open in the circumferential direction. Accordingly, different types of stamping tools are used, which makes the production of the laminated stator core relatively expensive.

[0006] In contrast to the prior art, the stator lamination according to the invention serves to provide a basis for a laminated stator core which may comprise, for example, a plurality of identical stator laminations.

[0007] In a particularly preferred embodiment, at least one of the bridges has a groove which opens inwardly in the radial direction. Opening inwardly in the radial direction is to be understood in particular to mean that the groove opens in the direction of the center point of the stator lamination. In another preferred embodiment, at least one of the bridges has a groove which opens outwardly in the radial direction.

[0008] It has proven to be advantageous if the portion of the first web remaining from the groove has a different radial distance from the center point of the stator core than the portion of the second web remaining from the groove.

[0009] In another preferred embodiment, at least one of the bridges has a groove which opens inwardly in the radial direction and a groove which opens outwardly in the radial direction. It has proven to be advantageous if the radial distance of the portion of the bridge remaining from the groove from the center point of the stator stack is different from the radial distance of the portion of the first bridge and the second bridge remaining from the groove from the center point of the stator stack.

[0010] It has proven to be advantageous if the stator laminations have pairs of identically designed bridges. In a particularly preferred embodiment, the pairs of identically designed bridges are each arranged diametrically opposite one another. In a further preferred embodiment, the groove is arranged centrally between two adjacent star-shaped elements with respect to the circumferential direction. In a particularly preferred embodiment, the bridge is narrowed by the groove in the radial direction by at least 50%.

[0011] In another preferred embodiment, a stator lamination is provided for a laminated stator core of a three-phase brushless DC motor. For this purpose, the stator lamination preferably has exactly six star elements and exactly six bridges. It has proven to be advantageous that exactly two bridges out of a total of six bridges each have only one groove, wherein the grooves open inwardly in the radial direction. In addition, it has proven to be advantageous that exactly two bridges out of a total of six bridges each have only one groove, wherein the grooves open outwardly in the radial direction. As a further preference, exactly two bridges out of a total of six bridges each have exactly two grooves, wherein, for each bridge, exactly one groove opens inwardly in the radial direction and exactly one groove opens outwardly in the radial direction.

[0012] With regard to a laminated stator core, this object is achieved by a laminated stator core which has a plurality of identical stator laminations as described above arranged one above the other in the axial direction and in particular comprises a plurality of such stator laminations.

[0013] It has been found that the laminated stator core according to the invention has a number of mechanical and magnetic advantages. From a mechanical point of view, it should be emphasized that there is a mechanical connection between the corresponding adjacent star elements in each stator lamination plane. This allows a more uniform force distribution of the compression assembly. Depending on the rotation of the stator laminations relative to each other, the rotor space can be closed or at least the penetration of particles above a certain particle size can be prevented. It has been found that, from a magnetic point of view, the laminated stator core according to the invention provides the basis for achieving a slightly higher average torque with lower torque ripple and lower iron losses. The forces that exist between the star and the yoke ring are evenly distributed for all stator laminations.

[0014] It has been shown to be particularly advantageous that two adjacent stator laminations are stacked one above the other in an offset manner. In a particularly preferred embodiment, a laminated stator core is provided for a three-phase brushless DC motor. In this case, it has been shown to be advantageous that two adjacent stator laminations are rotated 120 degrees relative to each other, in particular 120 degrees relative to each other in each case. The rotation can be a quotient of 360 degrees and the number of star elements or a multiple of the quotient. Therefore, in the example of exactly six star elements, it is 60 degrees, 120 degrees, etc. In the context of the present invention, rotation should be specifically understood to refer to a rotation around an imaginary rotation axis of the rotor to be arranged in the laminated stator core. As an alternative or in addition, when one or more identical stator laminations stacked one above the other in the axial direction are inserted into the laminated stator core, the one or more identical stator laminations can be rotated 180 degrees ("upside down"). It has been shown to be advantageous that the laminated stator core does not have a separate star element, that is, specifically, there is no star element that is not connected to the bridge in the same plane on both sides.

[0015] The present invention also provides a brushless DC motor, in particular a brushless DC motor for an electric tool, wherein the brushless DC motor has a laminated stator core of the above type. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Additional advantages will become apparent from the following description of the accompanying drawings. The accompanying drawings show particularly preferred exemplary embodiments of the present invention. The accompanying drawings, the specification and the claims contain many combined features. It will also be convenient for those skilled in the art to consider these features individually and to combine these features to form other reasonable combinations.

[0017] In the accompanying drawings, the same and similar components are indicated by the same reference numerals, in which:

[0018] Figure 1 A preferred exemplary embodiment of a stator lamination is shown;

[0019] Figure 2 shows a preferred exemplary embodiment of a laminated stator core; and

[0020] Figure 3 Shows Figure 2 Cross-sectional illustration of a laminated stator core. DETAILED DESCRIPTION

[0021] Figure 11 shows a preferred exemplary embodiment of a stator lamination 10 according to the invention. The stator lamination 10 is completely closed in the circumferential direction UR and has, for example, six star elements 1, 2, 3, 4, 5, 6. Two adjacent star elements are connected to each other in each case via a bridge B1, B2, B3. A total of six bridges are provided. This enables the stator lamination 10 to be used as the basis for a laminated core of a three-phase brushless DC motor, for example.

[0022] As from Figure 1 As can be seen in the figure, the stator lamination 10 has pairs of bridges B1, B2, B3 of identical design, each of which is arranged diametrically opposite to each other. Accordingly, the stator lamination 10 thus has three different "bridge types". Each of the bridges B1, B2, B3 is narrowed in the radial direction RR by means of at least one groove.

[0023] The first bridge B1 is provided with a groove N1 that opens outward in the radial direction RR. Another bridge B3 has a groove N3 that opens inward in the radial direction RR, that is, in the direction of the center point M of the stator lamination 10. The bridge B2 is characterized in that it has a groove N2 that opens inward in the radial direction RR and a groove N2' that opens outward in the radial direction RR. The grooves N1, N2, N2', N3 are each arranged centrally between two adjacent star-shaped elements with respect to the circumferential direction UR. The grooves N1, N2, N2', N3 extend over the entire thickness of the stator lamination 10 with respect to the axial direction of the stator lamination 10.

[0024] By means of the grooves N1, N2, N2', N3, the so-called remaining parts R1, R2, R3 of the bridges B1, B2, B3 are retained, and by means of these remaining parts, the stator lamination 10 continues to be completely closed in the circumferential direction UR. By structurally positioning the remaining parts R1, R2, R3 at different distances from the center point M of the stator lamination 10 and then rotating each stator lamination in the laminated stator core (see Figure 2 and Figure 3 ), which can produce an electromagnetically and mechanically optimized laminated stator core.

[0025] In the exemplary embodiment considered, the remaining portion R1 of the first bridge B1 left by the groove N1 has a radial distance L1 from the center point M of the stator lamination 10 that is different (i.e. shorter) than the radial distance of the remaining portion R2 of the bridge B2 left by the groove N2 from the center point of the stator lamination. Figure 1Again, the radial distance L2 of the remaining portion R2 of the bridge B2 left by the groove N2 from the center point M of the stator lamination 10 is shorter than the radial distance of the remaining portion R3 of the bridge B3 left by the groove N3 from the center point of the stator lamination. Figure 1 The radial distance of the remaining portion R3 is represented by L3. Figure 1 In the exemplary embodiment of the present invention, the following applies accordingly: L1 <L2<L3。

[0026] Figure 2 A laminated stator core 100 is shown, which has a plurality of identical stator laminations 10, 20, 30 arranged one above the other in the axial direction AR. Figure 1 For the sake of simplicity of illustration, only the first three stator laminations 10 , 20 , 30 are provided with reference numerals.

[0027] As from Figure 2 , the stator laminations 10, 20, 30 can be stacked in a manner rotated relative to one another (relative to the axis of rotation of the rotor not shown here) so that two adjacent stator laminations (i.e. stator laminations 10 and 20, or 20 and 30) are offset relative to one another. In other words, there are always two different types of bridges stacked one above the other in each case.

[0028] In this example, the stator laminations 10, 20, 30 are each rotated 120 degrees in the circumferential direction UR (in the viewing direction from top to bottom). That is, the first bridge B1 arranged between the first star element 1 and the second star element 2 of the first stator lamination 10 is Figure 2 . On the left side of this first bridge with respect to the circumferential direction UR, the first bridge (bridge of the first type) in the second plane (i.e. in the second stator lamination 20) is likewise denoted as B1. This is the first bridge between the fourth star element 4 and the fifth star element 5 of the stator lamination. On the right side of the bridge B1 with respect to the circumferential direction UR, the first bridge (bridge of the first type) in the third plane (i.e. in the third stator lamination 30) is likewise denoted as B1. This is again the first bridge between the first star element 1 and the second star element 5 of the stator lamination.

[0029] at last, Figure 3 Shown through Figure 2 1 , wherein, relative to the first stator lamination 10 shown here at the bottom, the section extends through bridges B1 (bridges of the first type) which are located diametrically opposite one another.

[0030] It can be clearly seen that two adjacent stator laminations are rotated 120 degrees relative to one another and that in each case two different types of bridges always overlap one another. Since the stator laminations in each plane are rotated 120 degrees, the stacking sequence repeats every four stator laminations. In other words, the first stator lamination, the fourth stator lamination, the seventh stator lamination, etc., will overlap one another in the imaginary projection.

[0031] List of Reference Numerals

[0032] 1..6 Star Element

[0033] 10, 20, 30 stator laminations

[0034] 100 Laminated stator core

[0035] AR Axial direction

[0036] M Center point

[0037] B1..B3 bridge

[0038] N1..N3 grooves

[0039] R1..R3 remaining part

[0040] RR Radial direction

[0041] UR Circumferential direction

Claims

1. A stator lamination (10) for a laminated stator core (100) of a brushless DC motor, wherein: The stator core (10) is completely closed in the circumferential direction (UR) and has a plurality of star elements (1, 2, 3, 4, 5, 6), wherein two adjacent star elements are connected to one another in each case via a bridge (B1, B2, B3). It is characterized in that the bridge (B1) is narrowed in the radial direction (RR) by means of at least one groove (N1, N2, N2', N3).

2. The stator lamination (10) according to claim 1, It is characterized in that At least one of the bridges (B3) has a groove (N3) opening inwardly in the radial direction (RR).

3. The stator lamination (10) according to claim 1 or 2, It is characterized in that At least one of the bridges (B1) has a groove (N1) opening outwardly in the radial direction (RR).

4. The stator core (10) according to claim 1, It is characterized in that The radial distance (L1) of the remaining portion (R1) of the first bridge portion (B1) left by the groove (N1) from the center point (M) of the stator lamination (10) is different from the radial distance of the remaining portion (R3) of the second bridge portion (B3) left by the groove (N3) from the center point of the stator lamination.

5. The stator core (10) according to claim 1, It is characterized in that At least one of the bridges (B2) has a groove (N2) opening inwardly in the radial direction (RR) and a groove (N2') opening outwardly in the radial direction (RR).

6. The stator lamination (10) according to claim 5, It is characterized in that The radial distance (L2) of the remaining part (R2) of the bridge portion (B2) left by these grooves (N2, N2') from the center point (M) of the stator stack (10) is different from the radial distance of the remaining part of the first bridge portion and the second bridge portion (B1, B3) left by the grooves (N1, N3) from the center point of the stator stack.

7. The stator core (10) according to claim 1, It is characterized in that The stator lamination stack (10) has pairs of bridges (B1, B2, B3) of identical design.

8. The stator lamination (10) according to claim 7, It is characterized in that These pairs of bridges ( B1 , B2 , B3 ) of identical design are each arranged diametrically opposite one another.

9. The stator core (10) according to claim 1, It is characterized in that The groove (N1, N2, N2', N3) is arranged centrally between two adjacent star-shaped elements with respect to the circumferential direction (UR).

10. A laminated stator core (100) for a brushless DC motor, It is characterized in that The laminated stator core (100) has a plurality of identical stator laminations (10, 20, 30) as claimed in one of the preceding claims arranged one above the other in an axial direction (AR), and in particular comprises a plurality of such stator laminations (10, 20, 30).

11. The laminated stator core according to claim 10, It is characterized in that Two adjacent stator laminations are stacked one on top of the other in an offset manner.

12. A brushless DC motor, It is characterized in that The brushless DC motor has the stator lamination according to claim 11 .

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