Stator lamination and laminated stator core
Patent Information
- Application Number
- EP2023786577
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-10-24
- Filing Date
- 2023-10-10
- Publication Date
- 2025-09-03
AI Technical Summary
The production of stator laminations for electric motors is costly due to the need for different types of laminations that are either closed or open in the circumferential direction, requiring various punching tools and resulting in higher production expenses.
The stator lamination features bridges with grooves that extend axially over its thickness, allowing for the creation of a stack using identical laminations, with grooves oriented inward or outward in the radial direction, enabling mechanical and magnetic optimization by varying the radial distance of bridge sections from the center.
This approach reduces production costs, enhances mechanical force distribution, seals the rotor chamber, prevents particle penetration, and achieves higher average torque with lower torque fluctuations and iron losses in brushless direct current motors.
Smart Images
Figure 1.1
Abstract
Description
[0001] Stator lamination and stator lamination package
[0002] The present invention relates to a stator lamination for a stator lamination stack of a brushless DC motor. The stator lamination is completely closed in the circumferential direction and has a plurality of star elements, with two adjacent star elements each connected to each other by a bridge.
[0003] Stator laminations of the type mentioned above are generally known from the prior art. EP 2 507 896 B1 discloses a method for producing a stator for an electric motor, in which a number of stator laminations are stacked to form a star-shaped laminated core consisting of circumferentially closed stator laminations with individual teeth connected to one another via pole shoe webs and of circumferentially open stator laminations with individual teeth spaced apart from one another to form a gap on the pole shoe side.
[0004] The object of the present invention is to provide a stator lamination which creates the basis for a stator lamination package which can be produced comparatively easily and inexpensively.
[0005] This problem is solved by having the bridge tapered in the radial direction by at least one groove. It has proven advantageous if the groove extends axially across the full thickness of the stator lamination.
[0006] The invention incorporates the finding that prior art stator lamination stacks—to achieve certain magnetic properties—must have stator laminations of different types, i.e., both circumferentially closed and circumferentially open stator laminations. Accordingly, different types of punching tools are used, which makes the production of stator lamination stacks comparatively expensive.
[0007] In a departure from the prior art, the stator lamination according to the invention creates the basis for a stator lamination package which can, for example, consist of a plurality of identical stator laminations.
[0008] In a particularly preferred embodiment, at least one of the bridges has a groove that is open inwards in the radial direction. By "open inwards in the radial direction" is meant in particular that the groove is open in the direction of a center point of the stator lamination. In a further preferred embodiment, at least one of the bridges has a groove that is open outwards in the radial direction. It has proven advantageous if a residual section of a first bridge remaining through the groove has a different radial distance from a center point of the stator lamination than a residual section of a second bridge remaining through the groove.
[0009] In a further preferred embodiment, at least one of the bridges has a groove that opens radially inward and a groove that opens radially outward. It has proven advantageous if a residual section of this bridge remaining through the grooves has a different radial distance from a center point of the stator lamination than a residual section of the first and second bridge remaining through the groove.
[0010] It has proven advantageous if the stator lamination has pairs of similarly designed bridges. In a particularly preferred embodiment, the pairs of similarly designed bridges are arranged diametrically opposite each other. In another preferred embodiment, the groove is arranged centrally between two adjacent star elements in the circumferential direction. In a particularly preferred embodiment, the bridge is tapered by at least 50 percent in the radial direction by the groove.
[0011] In a further preferred embodiment, the stator lamination is intended for use in a stator lamination stack of a brushless three-phase DC motor. For this purpose, the stator lamination preferably has exactly six star elements and exactly six bridges. It has proven advantageous if exactly two of the total of six bridges each have only one slot, wherein these slots are open inwards in the radial direction. It has also proven advantageous if exactly two of the total of six bridges each have only one slot, wherein these slots are open outwards in the radial direction. More preferably, exactly two of the total of six bridges each have exactly two slots, wherein - per bridge - exactly one slot is open inwards in the radial direction and exactly one slot is open outwards in the radial direction.
[0012] With regard to the stator lamination stack, the object is achieved by a stator lamination stack which has a plurality of identical stator laminations of the type described above, stacked on top of one another in the axial direction, and in particular consists of the plurality of such stator laminations.
[0013] It has been shown that the stator lamination stack according to the invention offers a number of mechanical and magnetic advantages. From a mechanical perspective, it is worth emphasizing that in each stator lamination level there is a mechanical connection between adjacent star elements. This leads to a more even force distribution of the interference fit. Depending on the rotation of the stator laminations relative to each other, a rotor chamber can be sealed or at least the penetration of particles above a certain particle size can be prevented. From a magnetic perspective, it has been shown that the stator lamination stack according to the invention creates the basis for a slightly higher average torque with lower torque fluctuations and lower iron losses. The forces prevailing between the star and the yoke ring are evenly distributed across all stator laminations.
[0014] It has proven particularly advantageous if two adjacent stator laminations are stacked incongruently with one another. In a particularly preferred embodiment, the stator lamination stack is intended for use in a brushless DC motor with three phases. In this case, it has proven advantageous if two adjacent stator laminations are rotated by 120 degrees with respect to one another, in particular are each rotated by 120 degrees with respect to one another. A rotation can result by a single or multiple of the quotient of 360 degrees and the number of star elements. In the example of exactly six star elements, this would be by 60 degrees, 120 degrees, etc. In the context of the present invention, a rotation is to be understood in particular as a rotation about an imaginary axis of rotation of a rotor to be arranged in the stator lamination stack.Alternatively or additionally, one or more of the identical stator laminations stacked axially can be folded 180 degrees ("upside down") into the stator lamination stack. It has proven advantageous if the stator lamination stack is free of individual star elements, i.e., in particular, free of star elements that are not connected on both sides by a bridge in the same plane.
[0015] The invention also leads to a brushless DC motor, in particular of an electric hand-held power tool, wherein the brushless DC motor has a stator core of the type described above.
[0016] Further advantages will become apparent from the following description of the figures. The figure illustrates a particularly preferred embodiment of the present invention. The figures, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.
[0017] In the figure, identical and similar components are numbered with the same reference numerals. It shows:
[0018] Fig. 1 shows a preferred embodiment of a stator lamination;
[0019] Fig. 2 shows a preferred embodiment of a stator laminated core; and Fig. 3 shows a sectional view of the stator laminated core of Fig. 2.
[0020] Examples of implementation:
[0021] A preferred embodiment of a stator lamination 10 according to the invention is shown in Fig. 1. 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 each connected to each other by a bridge B1, B2, B3. A total of six bridges are provided. Thus, the stator lamination 10 can serve, for example, as the basis for a laminated core of a three-phase brushless DC motor.
[0022] As can be seen from Fig. 1, the stator lamination 10 comprises pairs of identically designed bridges B1, B2, B3, each arranged diametrically opposite one another. The stator lamination 10 therefore has three different "bridge types." Each of the bridges B1, B2, B3 is tapered in the radial direction RR by at least one groove.
[0023] A first bridge B1 is equipped with a slot N1 that is open outwards in the radial direction RR. A further bridge B3 has a slot N3 that is open inwards in the radial direction RR, i.e., open towards a center point M of the stator lamination 10. The bridge B2 is characterized in that it has both a slot N2 that is open inwards in the radial direction RR and a slot N2' that is open outwards in the radial direction RR. The slots N1, N2, N2', N3 are each arranged centrally between two adjacent star elements with respect to the circumferential direction UR. The slots 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] Due to the aforementioned grooves N1, N2, N2', N3, so-called residual sections R1, R2, R3 remain from the bridges B1, B2, B3, over which the stator lamination 10 continues to be completely closed in the circumferential direction UR. By constructively positioning the residual sections R1, R2, R3 at different distances from the center point M of the stator lamination 10 and subsequently rotating a respective stator lamination in the stator lamination stack (cf. Figs. 2 and 3), an electromagnetically and mechanically optimized stator lamination stack can be created.
[0025] In the present exemplary embodiment, a residual section R1 of the first bridge B1 remaining through the slot N1 has a different, namely smaller, radial distance L1 to the center point M of the stator lamination 10 than a residual section R2 of the bridge B2 remaining through the slot N2. The radial distance of the residual section R2 is denoted by L2 in Fig. 1. The residual section R2 of the bridge B2 remaining through the slot N2 in turn has a smaller radial distance L2 to the center point M of the stator lamination 10 than a residual section R3 of the bridge B3 remaining through the slot N3. The radial distance of the residual section R3 is denoted by L3 in Fig. 1. In the exemplary embodiment of Fig. 1, L1 < L2 < L3 therefore applies.
[0026] Fig. 2 shows a stator lamination stack 100 comprising a plurality of identical stator laminations 10, 20, 30 stacked one on top of the other in the axial direction AR. These stator laminations are as shown in Fig. 1. For the sake of simplicity, only the first three stator laminations 10, 20, 30 are provided with reference numerals.
[0027] As can be seen from Fig. 2, the stator laminations 10, 20, 30 (relative to the rotational axis of a rotor not shown here) are stacked in such a way that two adjacent stator laminations, i.e., stator laminations 10 and 20, or 20 and 30, are incongruent to each other. In other words, two bridges of different types are always stacked on top of each other.
[0028] In the present example, the stator laminations 10, 20, 30 (viewed from top to bottom) are each rotated by 120 degrees in the circumferential direction UR. This means that the first bridge B1, which is arranged between the first star element 1 and the second star element 2 of the first stator lamination 10, can be found at the top in Fig. 2. In relation to the circumferential direction UR, to the left of it in the second plane - i.e. in the second stator lamination 20 - the first bridge (bridge of the first type) is also designated as B1. This is the first bridge which is located between the fourth star element 4 and the fifth star element 5 of the stator lamination. In relation to the circumferential direction UR, to the right of the bridge B1 in the third plane - i.e. in the third stator lamination 30 - the first bridge (bridge of the first type) is also designated as B1. This is the first bridge, which in turn is located between the first star element 1 and the second star element 5 of the stator lamination.
[0029] Finally, Fig. 3 shows a vertical section through the stator laminated core 100 of Fig. 2, wherein the section - with reference to the first stator laminate 10 shown below - runs through the bridges B1 (bridge of the first type) which are diametrically opposed to one another.
[0030] It is clearly visible that two adjacent stator laminations are each rotated 120 degrees relative to each other, and two bridges of different types are always stacked on top of each other. Since the stator laminations are rotated 120 degrees with each level, the stacking sequence repeats with every fourth stator lamination. In other words, the first, fourth, seventh, etc. stator laminations would be congruent to each other in an imaginary projection.
[0031] 1..6 star elements
[0032] 10, 20, 30 stator laminations
[0033] 100 stator lamination stack
[0034] AR axial direction
[0035] M center
[0036] B1..B3 bridges
[0037] N1..N3 grooves
[0038] R1..R3 remaining section
[0039] RR radial direction
[0040] UR circumferential direction
Claims
Patent claims Stator lamination (10) for a stator lamination stack (100) of a brushless DC motor, wherein the stator lamination (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 each connected to one another by a bridge (B1, B2, B3), characterized in that the bridge (B1) is tapered in the radial direction (RR) by at least one groove (N1, N2, N2', N3). Stator lamination (10) according to claim 1, characterized in that at least one of the bridges (B3) has a groove (N3) which is open inwards in the radial direction (RR). Stator lamination (10) according to claim 1 or 2, characterized in that at least one of the bridges (B1) has a groove (N1) which is open outwards in the radial direction (RR).Stator lamination (10) according to one of the preceding claims, characterized in that a residual section (R1) of a first bridge (B1) remaining through the groove (N1) has a different radial distance (L1) from a center point (M) of the stator lamination (10) than a residual section (R3) of a second bridge (B3) remaining through the groove (B3). Stator lamination (10) according to one of the preceding claims, characterized in that at least one of the bridges (B2) has a groove (N2) that is open inward in the radial direction (RR) and a groove (N2') that is open outward in the radial direction (RR). Stator lamination (10) according to claim 5, characterized in that a residual section (R2) of the bridge (B2) remaining through the grooves (N2, N2') has a different radial distance (L2) from a center point (M) of the stator lamination (10) than a residual section of the first and second bridge (B1, B3) remaining through the groove (N1, N3). Stator lamination (10) according to one of the preceding claims, characterized in that the stator lamination (10) has bridges (B1, B2, B3) of identical design in pairs. Stator lamination (10) according to claim 7, characterized in that the bridges (B1, B2, B3) of identical design in pairs are each arranged diametrically opposite one another. Stator lamination (10) according to one of the preceding claims, characterized in that the groove (N1, N2, N2', N3) is arranged centrally between two adjacent star elements with respect to the circumferential direction (UR). Stator lamination stack (100) for a brushless DC motor, characterized in that the stator lamination stack (100) has a plurality of identical stator laminations (10, 20, 30) stacked on top of one another in the axial direction (AR) according to one of the preceding claims, and in particular consists of the plurality of such stator laminations (10, 20, 30).A stator lamination stack according to claim 10, characterized in that two adjacent stator laminations are stacked incongruently to one another. A brushless DC motor, characterized in that the brushless DC motor has a stator lamination according to claim 11.