Rotor magnet assembly

Abstract

To provide a rotor magnet assembly enabling fast and secure attachment of magnets to a rotor.SOLUTION: This invention relates to a rotor magnet assembly (1) comprising at least one magnet (2), a base plate (3) accommodating the at least one magnet (2), and a cover part (9) arranged to secure the at least one magnet (2) against the base plate (3). The base plate (3) comprises at least two grooves (7), and a first branch (11) and a second branch (12) of a section (10) of the cover part (9) have a substantially U-shaped cross-section, each of which extends into one of the at least two grooves (7) and at least partially encloses the at least one magnet (2). Each of the first branch (11) and the second branch (12) is provided with a protrusion (13), and the rotor magnet assembly further comprises a tightening piece (14) for tightening the protrusion (13) towards a bottom surface (8) of the grooves (7).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotor magnet assembly comprising at least one magnet and a base plate, the magnet being fixed to the base plate by a cover portion. [Background technology]

[0002]

[0002] In electric motors and generators, a magnetic field is generated in the rotor that communicates with a magnetic field applied to the stator by magnetic field excitation, enabling power transmission between the stator and the rotor. The rotor's magnetic field may be generated by either permanent magnets or electromagnets, which are typically provided on the outer periphery of the rotor midsection. In the case of permanent magnets, several magnet blocks are typically fixed to the periphery of the rotor by mechanical coupling elements such as bolts or conductive bands.

[0003]

[0003] In known magnet mounting solutions, limited coupling forces are achieved to secure the magnets. This is often due to the relatively fragile structure of the magnets and the suboptimal direction and distribution of coupling forces at the interface between the magnets and the coupling elements. Due to the limited coupling forces, the magnet assembly can act as a limiting factor to the maximum allowable rotational speed of the rotor, thereby restricting the range of use of the motor or generator.

[0004] Another drawback of known solutions is that the magnets are typically fixed directly to the rotor, which means that the fixing can only be performed at the rotor position during assembly, which causes the rotor assembly process to be hindered by the magnet mounting, and the magnet mounting may need to be performed in a suboptimal working orientation. Summary of the Invention

[0005]

[0005] The object of the present invention is to provide a rotor magnet assembly which overcomes the above-mentioned drawbacks and allows for quick and reliable attachment of magnets to a rotor. This object is achieved by the arrangement according to independent claim 1.

[0006]

[0006] By providing an assembly having at least one magnet housed on a base plate and a cover portion arranged to secure the magnet to the base plate so that the branches of the cover portion extend into grooves in the base plate, it is possible to easily obtain a strong mechanical bond between the magnet and the base plate.

[0007]

[0007] Preferred embodiments of the invention are disclosed in the dependent claims. [Brief explanation of the drawings]

[0008]

[0008] The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which: [Figure 1]

[0009] FIG. 1 illustrates a first embodiment of a rotor magnet assembly. [Figure 2]

[0010] FIG. 2 illustrates a second embodiment of a rotor magnet assembly. [Figure 3]

[0011] FIG. 3 illustrates a third embodiment of a rotor magnet assembly. [Figure 4]

[0012] FIG. 4 illustrates the base plate of a fourth embodiment of a rotor magnet assembly. DETAILED DESCRIPTION OF THE INVENTION

[0009]

[0013] FIG. 1 illustrates a cross section of a first embodiment of a rotor magnet assembly 1, as the assembly is shown mounted to a rotor 5. As seen in this example, the assembly includes a base plate 3 having a first surface 4 for mounting to the rotor 5 and an opposite second surface 6. In this case, the assembly is provided with a plurality of magnets 2 housed on the second surface 6; in other embodiments of the assembly 1, any other number of magnets 2, such as only one, may be provided. Mounting to the rotor 5 may be achieved, for example, by a fixing bolt 28 extending through the base plate 3 and to the rotor 5, as shown in FIG. 1. In this example, the first surface 4 is provided as an arcuate surface that matches the curvature of the rotor circumference, and the second surface 6 is provided as a flat surface on which the magnets 2 are positioned. Each magnet 2 is also provided with a flat surface that forms contact with the second surface 6. However, in other embodiments of the assembly 1, the second surface 6 may also be provided with a slot for housing the magnet 2, for example, or the contact surfaces of the second surface 6 and the magnet 2 may be shaped relative to one another to allow them to be locked into a predetermined relative position.

[0010]

[0014] 1, the base plate 3 comprises a plurality of grooves 7 opening onto the second surface 6, each of the grooves 7 having a bottom surface 8. In this case, bottom surface 8 refers to the inner surface of the groove 7 opposite the opening onto the second surface 6. In other embodiments of the assembly 1, any number of grooves 7 greater than one may be provided. For example, when the assembly 1 comprises only one magnet 2, at least two grooves 7 are required.

[0011]

[0015] As can be seen in the example of FIG. 1 , the assembly 1 further comprises a cover part 9 arranged to fix the magnets 2 relative to the base plate 3. The cover part 9 in this example has multiple parallel sections 10 with a substantially U-shaped cross section, although in other embodiments, for example, only one section 10 may be provided. The sections 10 may be provided as individual parts that are attached to each other, for example by gluing, or as separate parts that are only locked into position in a final assembly step. Each U-shaped section 10 has a first branch 11 and a second branch 12 that partially surround one of the magnets 2 between them, and the first branch 11 and the second branch 12 each extend into one of the grooves 7. More precisely, each magnet 2 in this case is surrounded by the branches 11, 12 on three sides while touching the outside of the cover part 9 on its two opposite sides. As shown in the example of Figure 1, when the assembly 1 comprises several U-shaped sections 10, adjacent branches 11, 12 of each adjacent section 10 extend into the same groove 7. In this configuration, said adjacent branches 11, 12 are guided into contact with each other by the groove 7.

[0012]

[0016] As can be seen in the example of FIG. 1 , each of the first branch 11 and the second branch 12 includes a protrusion 13 such that the protrusions 13 in different branches extend toward each other. In this example, the first branch 11 and the second branch 12 are also provided with a fixing bar 16 in each of the grooves 7, which rigidly connects the branches. In this case, the fixing bar 16 partially forms the protrusion 13 in each of the first branch 11 and the second branch 12. In the arrangement as disclosed, the fixing bar 16, which may be made of a strong, non-flexible material such as steel or other metal, may be used to provide a rigid fixing point between the base plate 3 and the cover portion 9 in each of the first branch 11 and the second branch 12. In some embodiments, the protrusion 13 may be completely formed by the fixing bar 16, or the protrusion 13 may be completely formed as an integral part of the cover portion 9 without the use of the fixing bar 16.

[0013]

[0017] The rotor magnet assembly 1 also includes a fastening element 14 in each groove 7 for fastening the protrusion 13 toward the bottom surface 8. In the example of FIG. 1 , the fastening element 14 is provided as a fastening bolt 17 that extends from the first surface 4 through the base plate 3 to the inside of the protrusion 13 and threads onto the protrusion 13, thereby allowing the protrusion 13 to be pulled toward the bottom surface 8 when the fastening bolt 17 is tightened. This pulls the cover part 9 toward the magnet 2 provided between the first branch 11 and the second branch 12, thereby fixing the magnet 2 to the base plate 3 by compression. More precisely, in the example of FIG. 1 , the fastening bolt 17 extends inside the fixing bar 16 that partially forms the protrusion 13. In the example of FIG. 1 , the base plate 3 is provided with a through hole 26 extending between the first surface 4 and the groove 7 for receiving the fastening bolt 17, the through hole 26 being arranged to be wider near the first surface 4 so as to receive the head of the bolt 17. In other embodiments of the assembly, screws may be used instead of bolts.

[0014]

[0018] In the example of Figure 1, the parts of the projections 13 that connect to the fixing bars 16 are shaped to have a wedge-like shape, so that their thickness increases towards their lower part, in other words towards the bottom surface 8 of the groove 7. At the same time, the fixing bars 16 are also wedge-shaped, so that their thickness decreases towards the bottom surface 8. With said arrangement, when the clamping bolts 17 are tightened, the wedge-shaped fixing bars 16 press against the wedge-shaped shapes of the branches, thereby ensuring an interference fit between the branches 11, 12 and the fixing bars 16, as well as between the branches and the walls of the groove 7.

[0015]

[0019] FIG. 2 illustrates a cross section of a second embodiment of the rotor magnet assembly 1. This example shares most of the structural features disclosed above in connection with the example of FIG. 1, and therefore most of the features characteristic of this second embodiment will be described here. In both the examples of FIGS. 1 and 2, the base plate 3 includes a flange 15 in each groove 7 that extends along the second surface 6 at the top of the groove 7. In other words, the flange 15 is provided to limit the width of the groove 7 in the area of ​​its opening to the second surface 6, where the groove 7 has a wider section at its lower part below the flange 15 to accommodate the protrusions 13 of the first branch 11 and the second branch 12. In both examples, the flange 15 and the protrusion 13 in each of the grooves 7 are shaped relative to one another to prevent the cover portion 9 from moving more than a predetermined distance in a direction perpendicular to the bottom surface 8 of the groove 7. In other words, in the above arrangement, the opening width of the groove 7 is smaller than the width of the protrusion 13, so that the flange 15 prevents the cover portion 9 from coming off the base plate 3 as a result of pulling the rotor 5 radially after the assembly 1 is attached to the rotor 5.

[0016]

[0020] 1 and 2, the base plate 3 also has two opposing side surfaces 25 extending between the first surface 4 and the second surface 6, in which the groove 7 also opens onto these side surfaces 25. With this arrangement, the first branch 11 and the second branch 12 of the cover part 9 can be inserted into their correct position in the groove 7 through the side surfaces 25, so that the flange 15 does not hinder the insertion. In some embodiments, the groove 7 may also open onto only one of the side surfaces 25.

[0017]

[0021] 2, the clamping elements 14 are provided as wedges 18 arranged in each of the grooves 7 between the projections 13 and the flanges 15. More precisely, in this example, the projections 13 are also shaped to have a wedge-like shape on the side that contacts the wedges 18, and the grooves 7 are provided with form-matching slots that accommodate the wedges 18. With this arrangement, no clamping bolts or screws are needed to fix the magnets 2, since clamping can be achieved by pressing the wedges 18 into their final position in the dedicated slots and having the wedges 18 press the projections 13 towards the bottom surface 8 of the slots 7. The contact surfaces between the projections 13 and the wedges 18 are oriented obliquely with respect to the extension direction of the slots 7, so that an interference fit is ensured between the branches 11, 12 and the wedges 18, as well as between the branches and the walls of the grooves 7, when the wedges 18 are pressed into their final position. However, in some embodiments, the protrusion 13 and groove 7 may be shaped such that a gap is formed between them, for example extending in the direction of the second surface 6, and a wedge 18 may be provided within this gap to press the protrusion 13 directly towards the bottom surface 8 of the gap 7.

[0018]

[0022] 3 illustrates a cross-section of a third embodiment of the rotor magnet assembly 1, in which different cross-sections are shown to the left and right of the vertical mid-plane 27 of the assembly, as indicated by dashed lines. Since this example shares most of the structural features disclosed above in relation to the examples of FIGS. 1 and 2, most of the features characteristic of this third embodiment will now be described. In the example of FIG. 3, the fastening elements 14 are provided as clamping screws 17 that extend from the first surface 4 to the flange 15 through the protrusions 13 and the base plate 3 and threadably engage with the protrusions 13. More precisely, the assembly of this embodiment also comprises a fixing bar 16 that partially forms the protrusions 13 in each of the grooves 7, so that the fastening screws 17 extend through the fixing bar 16 to the flange 15 and threadably engage with the fixing bar 16. In the arrangement as disclosed, the flange 15 provides a surface facing the protrusions 13 in each of the grooves 7, said surface acting as a counter surface against which the fastening screws 17 bear during fastening.

[0019]

[0023] 3 also illustrates the connection between the branches 11, 12 of the cover part 9 and the fixing bar 16. In the illustrated arrangement, the first branch 11 and the second branch 12 are provided with first through holes 19 that align with second through holes 20 provided in the corresponding fixing bar 16, and fixing pins 21 are provided that extend from the first through holes 19 to the corresponding second through holes 20. Using the disclosed arrangement, a strong connection between the branches 11, 12 and the fixing bar 16 can be obtained against pulling in the radial direction of the rotor 5 after the assembly 1 is attached to the rotor 5. The arrangement can also be easily disassembled if necessary, since the fixing pins 21 are not fixedly connected to the branches 11, 12 or the fixing bar 16.

[0020]

[0024] In the example of FIG. 1 , the rotor magnet assembly 1 also includes an adapter piece 24 disposed between the magnet 2 and the cover portion 9 in each of the sections 10, which have a substantially U-shaped section. The outer shape of the adapter piece 24 in this example corresponds to the inner shape of the section 10, thereby serving as a shape adapter for accommodating a magnet block in an assembly having an outer shape that does not match the shape of the cover portion 9. This allows for greater freedom in shaping the sections 10 of the cover portion 9 and the magnet 2, since their shapes do not need to correspond to each other. The adapter piece 24 is preferably made of a magnetoresistive material, such as a resistive metal alloy. The cover portion 9 is also preferably made of a magnetoresistive material with high rigidity and mechanical strength, such as carbon fiber. In some embodiments, several magnets 2 may also be housed in the same section 10 of the cover portion 9, so that these magnets 2 fit the internal shape of the section 10, with or without the adapter piece 24. Also, in an arrangement where only one magnet 2 is accommodated in the U-shaped section 10 without the use of an adapter piece 24, the outer shape of the magnet 2 may be formed to directly correspond to any given change in the internal shape of the section 10.

[0021]

[0025] FIG. 4 shows a cross section of a base plate 3 according to a fourth embodiment of the rotor magnet assembly 1. In this example, the base plate 3 comprises a base segment 22 having a first surface 4 and a plurality of parallel upper segments 23 spaced apart from one another and connected to the base segment 22. The connection may be achieved, for example, by using fastening bolts or screws extending between the base segment 22 and the upper segments 23. The upper segments 23 mutually define second surfaces 6, such that the second surface 6 is formed by the upper surfaces of the upper segments 23 facing away from the base segment 22, and grooves 7 are formed between adjacent upper segments 23. In this configuration, the bottom surfaces 8 of the grooves 7 are formed on the surface of the base segment 22 that houses the upper segments 23. With the disclosed arrangement, the shape and number of grooves 7 can be adjusted as desired using the same configuration of base segments 22, further increasing the modularity of the assembly 1. Another advantage of this arrangement is that the base segment 22 and top segment 23 can be easily manufactured as separate units using conventional machining methods, as opposed to a unitary configuration where grooves 7 must be formed in a single base plate preform. The example of Figure 4 also illustrates an alternative method for attaching the base plate 3 to the rotor 5, where the first surface 4 of the base plate 3 is provided with a locking protrusion 29 that is arranged to connect to a groove provided in the rotor 5 via a form-locking dovetail arrangement.

[0022]

[0026] It should be understood that the above description and accompanying drawings are only intended to illustrate the present invention. It will be apparent to those skilled in the art that changes and modifications can be made to the present invention without departing from the scope of the invention.

Claims

1. A rotor magnet assembly (1) comprising at least one magnet (2), said assembly comprising: a base plate (3) having a first surface (4) for mounting to a rotor (5) and an opposite second surface (6) for accommodating said at least one magnet (2); wherein said base plate (3) is provided with at least two grooves (7) opening into said second surface (6), each groove (7) having a bottom surface (8); and a cover portion (9) arranged to fix at least one magnet (2) to the base plate (3), wherein: the cover part (9) has at least one section (10) with a substantially U-shaped cross section having a first branch (11) and a second branch (12) which partially surround at least one magnet (2) therebetween, wherein the first branch (11) and the second branch (12) each extend into one of the at least two grooves (7); The first branch (11) and the second branch (12) each have a protrusion (13), the protrusions (13) extending towards each other; The rotor magnet assembly (1) further comprises a fastening part (14) in each of the at least two grooves (7) for fastening the protrusion (13) toward the bottom surface (8).

2. 2. A rotor magnet assembly (1) according to claim 1, characterized in that the base plate (3) comprises a flange (15) in each groove (7) extending along the second surface (6) at the top of the groove (7).

3. 3. A rotor magnet assembly (1) according to claim 1 or 2, characterized in that the first branch (11) and the second branch (12) of the cover part (9) are provided with fixing bars (16) in each of the at least two grooves (7), and the fixing bars (16) at least partially define the protrusions (13) on each of the first branch (11) and the second branch (12).

4. 4. The rotor magnet assembly (1) according to claim 1, wherein the fastening part (14) is provided as a fastening bolt (17) that extends from the first surface (4) through the base plate (3) to the inside of the protrusion (13) and is threadedly engaged with the protrusion (13), and comprises a fastening screw or bolt (17).

5. 3. The rotor magnet assembly (1) according to claim 2, characterized in that the fastening part (14) comprises a fastening screw or bolt (17) that extends from the first surface (4) to the flange (15) through the protrusion (13) and the base plate (3) and threads onto the protrusion (13).

6. The rotor magnet assembly (1) according to claim 3, which is dependent on claim 2, characterized in that the fastening part (14) comprises a fastening screw or bolt (17) which extends from the first surface (4) through the fixing bar (16) and the base plate (3) to the flange (15) and is threadedly engaged with the fixing bar (16).

7. 3. The rotor magnet assembly (1) according to claim 2, characterized in that the fastening part (14) comprises a wedge (18) provided in each of the at least two grooves (7) between the protrusion (13) and the flange (15).

8. A rotor magnet assembly (1) according to any one of claims 5 to 7, which is dependent on claim 2, characterized in that the flange (15) and the protrusion (13) in each of the at least two grooves (7) are shaped relative to each other so as to prevent the cover part (9) from moving in a direction opposite to the bottom surface (8) of the groove (7) beyond a predetermined distance.

9. 7. The rotor magnet assembly (1) according to claim 3 or 6, characterized in that the first branch (11) and the second branch (12) are provided with first through holes (19) that align with second through holes (20) provided in the corresponding fixing bars (16), and the rotor magnet assembly (1) further comprises fixing pins (21) that extend from the first through holes (19) to the corresponding second through holes (20).

10. The rotor magnet assembly (1) comprises a plurality of magnets (2) housed in the base plate (3), the cover part (9) having a plurality of sections (10) arranged parallel to one another and having a substantially U-shaped cross section, the first branch (11) and the second branch (12) of each section (10) partially surrounding one of the magnets (2) therebetween; 10. A rotor magnet assembly (1) according to any one of claims 1 to 9, characterized in that the base plate (3) comprises a plurality of grooves (7) opening into the second surface (6), wherein adjacent branches (11, 12) of each adjacent section (10) extend into the same groove (7).

11. 11. A rotor magnet assembly (1) according to any one of claims 1 to 10, characterized in that the base plate (3) comprises a base segment (22) having the first surface (4) and a plurality of parallel upper segments (23) connected to the base segment (22) at a distance from each other and mutually defining the second surface (6), wherein the at least two grooves (7) are formed between adjacent upper segments (23).

12. 12. The rotor magnet assembly (1) according to any one of claims 1 to 11, characterized in that the rotor magnet assembly (1) further comprises an adapter piece (24) arranged between the at least one magnet (2) and a cover part (9), the outer shape of the adapter piece (24) corresponding to the inner shape of the section (10) of the cover part (9) having a substantially U-shaped cross section.

13. 13. A rotor magnet assembly (1) according to any one of claims 1 to 12, characterized in that the base plate (3) has two opposing side surfaces (25) extending between the first surface (4) and the second surface (6), and the at least two grooves (7) open into at least one of the side surfaces (25).

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