Rotor sheet stack and method for introducing magnets into the rotor sheet stack

Abstract

Rotor sheet stack (1) with at least one segment (2) and at least one magnet window (4) for receiving a magnet (4), wherein the segment (2) forms a tongue (5), wherein the tongue (5) is formed centrally with respect to the center of gravity (7) of the magnet (3), which projects radially into the magnet window (4) from the outer region (2b) of the segment (2) and the tongue (5) forms an overlap (6) with the magnet (3).

Description

[0001] The invention relates to a rotor lamination stack with at least one segment and at least one magnetic window for receiving a permanent magnet.

[0002] The invention also relates to a method for introducing magnets into a rotor lamination stack. State of the art

[0003] The synchronous motor is a type of motor used in electric cars. There are two types of electric motors in electric cars: permanent magnet synchronous motors (PMMs) and separately excited induction motors (ASMs). PMMs offer several advantages, including higher power density and higher efficiency. This means they can generate more power in a smaller space and use electrical energy more efficiently. However, PMMs are more expensive than ASMs and require the use of rare earth elements, which increases their manufacturing costs and environmental impact.

[0004] However, the ASM has a lower power density and a lower efficiency compared to the PSM.

[0005] In a PSM motor, permanent magnets are installed in the rotor stack. To secure a permanent magnet in a rotor recess, it is conventionally pressed into the recess and clamped using at least one clamping lug. The clamping lug is located on the side of the permanent magnet facing the axis of rotation and not only fixes the permanent magnet radially but also holds it axially. With this technology, the permanent magnet is exposed to high mechanical stress, and its surface and / or coating are frequently scratched, especially during pressing into the recess and / or under operating conditions of the rotor or stator.

[0006] DE10 2010 039 334 A1 discloses an electrical machine having a rotor or stator arranged concentrically around a rotational axis, with a permanent magnet arranged in a recess of the rotor or stator, wherein an elastic fixing means for fixing the permanent magnet in the recess is also arranged in the recess of the rotor or stator. The fixing means is an additional component and is not manufactured integrally with the rotor core or laminations of the rotor core, but rather is manufactured separately and arranged in the recess. Since the fixing means is designed to be elastic according to the invention, it has a defined spring behavior and / or mechanical clamping behavior. As a result, it can be dimensioned such that both the component tolerances of the permanent magnet and its temperature behavior can be compensated for by the fixing means across the range of temperatures prevailing in the rotor or stator.

[0007] Local overloading of the rotor stack material leads to high mechanical stresses and possible material breakouts of the sub-segments.

[0008] The object of the invention is to propose a rotor with magnets which reduces the mechanical stresses with a focus on the radii adjacent to the magnets in the sheet metal cut. Description of the invention

[0009] The object is achieved with a rotor lamination stack having at least one segment and at least one magnet window for receiving a permanent magnet, wherein the segment forms a tongue, wherein the tongue is formed centrally with respect to the center of gravity of the magnet, which protrudes radially from the outer region of the segment into the magnet window and the tongue forms an overlap with the magnet.

[0010] The magnet forms a bridge between the outer area of ​​the segment and the inner area of ​​the segment via centering and compression at the center of gravity.

[0011] At least the magnets attached to the outer circumference of the rotor core are pressed and held centrally.

[0012] Only the magnets mounted centrally on the outer circumference of the rotor core are pressed and held in place.

[0013] The object is also achieved with a method for introducing magnets into a rotor lamination stack having at least one magnet window, wherein the laminations of the rotor lamination stack and the segments are punched to form the at least one magnet window and a tongue centrally with respect to the center of gravity of the magnet to be mounted, which tongue projects radially into the magnet window from the outer region of the segment, and wherein the at least one magnet is pressed into the magnet window, wherein the tongue is bent for the press-in process.

[0014] By specifically fixing the outer magnets of a PSM rotor using a press fit, an additional material bridge is created directly through the magnets, which relieves the surrounding areas.

[0015] This leads to an increased rotor lifespan and better magnet fixation. The height of the saturation bars in the sheet metal section can be reduced, so less magnet material is required. Description of the characters Fig. 1 shows a section of a segment of a rotor lamination stack, Fig. Figure 2 shows a graph of stress levels over time.

[0016] Fig. 1 shows a segment 2 of a rotor lamination stack 1 in a plan view along the rotor axis R. The segment has a magnet window 4, the dimensions of which approximately follow the dimensions of a magnet 3. The magnet window 4 has projections 4a that form cavities on the narrow sides of the magnet 3. These projections can be used as cooling channels. The segment 2 of the rotor lamination stack 1 has an outer region 2b that extends from the magnet window to the outer circumference 2a. Starting from this outer region 2b, a tongue 5 is formed that projects into the magnet window 4.

[0017] The magnets 4 are pressed locally into the respective magnet window, whereby the tongue 5 must be elastically bent. The magnets are then fixed by a press fit and held in their desired position.

[0018] The assembly is carried out in such a way that the magnets 4 are positioned centrally in relation to the magnet window 4 in the rotor lamination stack 1 and are held centrally there by the overlap 6 of the tongue 5. The center of gravity of the magnets 4 is in the Fig. 1 with reference numeral 7. The press fit creates a connection between the outer region 2b and the inner region of the segment 2. The magnet 4 forms a connecting bridge between the inner and outer regions. This connecting bridge stabilizes the outer region 2b of the rotor core 1 and thus reduces the mechanical stresses in the critical radii.

[0019] The press fit extends over the entire length of the rotor core.

[0020] The overlap 6 with the tongue 5 must be provided in the sheet metal cut during the manufacture of the rotor laminations. This is advantageous for the outer magnets because the material of the sheet metal cut can be elastically bent or pushed away in this area, thus keeping the insertion force within a non-problematic range. Furthermore, the risk of breakage is greatest in the outer area.

[0021] Fig. Figure 2 shows the dynamic load over time. Curve 10 describes the rotor angular velocity. Curve 11 shows a very high load when the magnets are installed without the inventive solution. Curve 12 shows a significant reduction in load through the use of center-centered and clamped magnets. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2010 039 334 A1

[0006]

Claims

[1] Rotor lamination stack (1) with at least one segment (2) and at least one magnet window (4) for receiving a magnet (4), wherein the segment (2) forms a tongue (5), wherein the tongue (5) is formed centrally with respect to the center of gravity (7) of the magnet (3), which tongue projects radially from the outer region (2b) of the segment (2) into the magnet window (4) and the tongue (5) forms an overlap (6) with the magnet (3). [2] Rotor lamination stack (1) according to claim 1, characterized by that the magnet (3) forms a bridge between the outer region (2b) of the segment (2) and the inner region of the segment (2) via the centering and pressing at the center of gravity (7). [3] Rotor lamination stack (1) according to claim 1 or 2, characterized by that at least the magnets (3) attached to the outer circumference (2a) of the rotor core (1) are pressed and held centrally. [4] Rotor lamination stack (1) according to claim 1 or 2, characterized bythat only the magnets (3) attached to the outer circumference (2b) of the rotor core (1) are pressed and held centrally. [5] Method for introducing magnets (3) into a rotor lamination stack (1) with at least one magnet window (4), wherein the laminations of the rotor lamination stack (1) and the segments (2) are punched in order to form the at least one magnet window (4) and a tongue (5) centrally with respect to the center of gravity (7) of the magnet (3) to be mounted, which tongue projects radially into the magnet window (4) from the outer region (2b) of the segment (2), and wherein the at least one magnet (3) is pressed into the magnet window (4), wherein the tongue (5) is forced away for the pressing-in process.

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