Rotor cover plate, rotor, and method for attaching rotor

Abstract

To improve the method for assembling a rotor.SOLUTION: A cover plate for a rotor of an electric machine has a contact surface intended to contact a laminated core of the rotor, the rotor is rotatable about an axis of rotation and has a laminated core, at least one cover plate is arranged at an axial end of the laminated core, and a method for mounting the rotor, the cover plate and the laminated core are arranged on a rotor shaft, a permanent magnet is arranged in a first recess of the laminated core, and the recess is filled with plastic to embed the permanent magnet in the first recess.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present application relates to a cover plate for a rotor of an electric machine, the cover plate having a contact surface intended to abut against a laminated core of the rotor, a rotor for an electric machine, rotatable about an axis of rotation and having a laminated core, at least one cover plate being arranged at an axial end of the laminated core, and a method for mounting the rotor, the cover plate and the laminated core being arranged on a rotor shaft, a permanent magnet being arranged in a first recess of the laminated core, and the recess being filled with plastic to embed the permanent magnet in the first recess. [Background technology]

[0002] Such electric machines are known from the state of the art. They comprise a stator and at least one rotor rotatable about an axis of rotation relative to the stator.

[0003] DE 102020128552 A1 relates to a rotor for a permanent magnet synchronous machine having a laminated core with recesses in which the respective permanent magnets are accommodated. The recesses have a first end closer to the axis of rotation of the rotor than the second end. In the recesses adjacent to each other and with the first end closer to each other in the circumferential direction of the rotor than the second end, the permanent magnets are arranged with their magnetic poles N facing each other. A rotor arranged in such a permanently excited synchronous machine has clamping or cover discs between which the laminated cores are pressed against each other. Boreholes can be made in several positions in these clamping discs. By providing boreholes corresponding to one or more of these positions, the rotor can be balanced or an unbalance in the rotation of the rotor can be eliminated.

[0004] DE 19915664 A1 discloses an electric machine with a stator and a rotor with at least one laminated core, which has the following features: at least two different lamination cuts of laminations of the laminated core, at least one lamination of the lamination cuts being provided with means for radially fixing the individual laminations in the laminated core, in particular when they are axially assembled. The laminated core of the rotor has recesses for permanent magnets, which can be fixed by inserting a hardenable compound. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] DE 102020128552 [Patent Document 2] DE 19915664 A1 Summary of the Invention [Problem to be solved by the invention]

[0006] An object may be to improve the method for assembling a rotor. [Means for solving the problem]

[0007] This object is achieved by a cover plate according to claim 1, a rotor according to claim 8 and a method for mounting a rotor according to claim 13. The dependent claims each contain further embodiments.

[0008] The cover plate of the rotor of the electric machine has a contact surface intended to contact the laminated core of the rotor, at least one ventilation duct being formed in the contact surface in the form of a groove.

[0009] When assembling a rotor for a permanent magnet synchronous machine with integral permanent magnets (IPMSM), the permanent magnets are inserted into cavities provided for this purpose in the laminated cores. The laminated cores with the inserted permanent magnets are placed together on a rotor shaft with shoulders on which the laminated cores are supported. The rotor shaft has an axis of rotation. References to axial, radial and circumferential directions generally refer to this axis of rotation. Cover plates are placed at both axial ends of the laminated cores, which are used to compensate for end imbalances of the rotor assembly, for example by drilling boreholes in the cover plates. They are therefore also known as balancing washers or compensating disks. In the case of rotor shafts with shoulders, it is not possible to retrofit one of the cover plates. This can only be done before mounting the laminated cores on the rotor shaft. To embed the magnets, the cavities are overmolded with a hardening plastic. Air has to escape from the cavities, but is prevented by the cover plates already in place. Thus, according to the invention, the cover plates have ventilation ducts through which the air can advantageously escape. Ventilation ducts in the form of grooves in the contact surfaces that contact the laminated core allow air to escape from the cavities occupied by the permanent magnets to other cavities of the laminated core that remain unoccupied.

[0010] According to one embodiment, it is provided that the ventilation duct is shaped and / or dimensioned so that air can escape through it, and the hardenable plastic hardens in the ventilation duct before the hardenable plastic can escape from it. For this purpose, the ventilation duct can have a maximum extension in a direction perpendicular to the plane formed by the contact surfaces of less than 0.2 mm, preferably less than 0.1 mm, particularly preferably 0.03 mm to 0.05 mm. The direction perpendicular to the plane formed by the contact surfaces corresponds to the axial direction. This means that the ventilation duct does not extend into the cover plate more than its axial maximum extension. To ensure that the hardenable plastic hardens, it may be sufficient for the ventilation duct to have a specified maximum extension in the cross section.

[0011] According to one embodiment, the ventilation duct may have several duct sections which are not necessarily connected. The ventilation duct may extend continuously or intermittently around the periphery of the cover plate.

[0012] According to a further embodiment, the ventilation duct has a thickness of 0.5 mm 2 Less than 0.2 mm, preferably 2 Less than 0.10 mm, particularly preferably 2 ~0.15mm 2 It is further provided that the ventilation duct has a cross-sectional area of ​​100 mm. Furthermore, the first dimension of the ventilation duct, which determines the cross-sectional area, can be significantly larger than the second dimension of the ventilation duct, which determines the cross-sectional area, in particular at least 20 times larger, preferably at least 50 times larger, particularly preferably about 60 times larger. The size and shape of the ventilation duct allow the ventilation of air. The hardening plastic hardens quickly in the ventilation duct thus dimensioned, closes it and therefore advantageously does not enter the unoccupied cavities of the laminated core. The first dimension of the ventilation duct, which determines the cross-sectional area, can be its width across the axis of rotation. The second dimension of the ventilation duct, which determines the cross-sectional area, can be the stretch in the direction perpendicular to the plane formed by the contact surfaces, which can also be called the axial stretch. In the case of a rectangular cross section, the first dimension determining the cross-sectional area is the long side of the rectangle and the second dimension determining the cross-sectional area is the short side of the rectangle. The long side can be, for example, 3 mm long and the short side can be, for example, 0.05 mm long. The cross-sectional area can have other shapes, such as a semi-oval or semi-elliptical shape. The first dimension of the ellipse that determines the cross-sectional area is the maximum distance between the center and the ellipse, and the second dimension that determines the cross-sectional area is the minimum distance between the center and the ellipse.

[0013] Depending on the position of the cavity in the laminated core, the shape of the ventilation ducts can be adapted to allow the described ventilation. For example, the ventilation ducts can have at least one outer duct section, one inner duct section and one radial duct section, the outer duct section being arranged radially outward of the inner duct section and the outer duct section being connected to the inner duct section via the radial duct section. In particular, this allows the ends of the cavities for permanent magnets, which have different radial distances to the axis of rotation, to be connected to the ventilation duct. The magnets of each pole are often arranged in pairs in a V-shape relative to each other, so that the ends of the cavities for permanent magnets have different radial distances to the axis of rotation.

[0014] The inner duct portion and / or the outer duct portion may be circumferentially continuous. Furthermore, there may be a plurality of outer duct portions, each of which is connected to a continuous inner duct portion via a radial duct portion.

[0015] According to a further embodiment, positioning means are provided which determine a defined position of the cover plate in the circumferential direction relative to the rotor.

[0016] According to a further embodiment, it is provided that the cover plate is a cast part.

[0017] A further subject of the present application relates to a rotor of an electric machine, rotatable about a rotation axis and having a laminated core, at least one of the cover plates being designed as described above and arranged at the axial end of the laminated core.

[0018] According to one embodiment, it is provided that the laminated core has a first recess and a second recess, the first recess being provided for accommodating a permanent magnet.

[0019] According to a further embodiment, it is provided that at least the ends of the first recess and the second recess are fluidly connected to a ventilation duct.

[0020] According to a further embodiment, it is provided that the first recess for embedding a permanent magnet is filled with a hardenable plastic, which extends into a partial region of the ventilation duct.

[0021] According to a further embodiment, it is provided that the laminated core is fixedly connected to a rotor shaft, the rotor shaft having opposing locating means which, together with the locating means, determine the relative circumferential position of the cover plates and the rotor shaft.

[0022] According to a further embodiment, it is provided that the rotor shaft has a shoulder on which the laminated core is supported, the cover plate being arranged between the shoulder and the laminated core.

[0023] A further object of the present application relates to a method for assembling the above mentioned rotor, wherein the cover plate and the laminated core are placed on a rotor shaft, the permanent magnets are placed in first recesses of the laminated core, the first recesses are filled with a hardenable plastic to embed the permanent magnets in the first recesses, and the first recesses are ventilated during the filling with plastic by evacuating air through a ventilation duct into the second recess.

[0024] The risk of plastic getting between the laminations of the laminated core or escaping outside the laminated core is advantageously reduced. A visual quality check can be carried out from the non-sealed side of the laminated core via the second recess. This makes it possible to recognize whether the plastic has penetrated the second recess. From a cost point of view, the cover plate can be cast without the need for complex post-processing. The tool for filling the first recess can be advantageously simplified, since the function of ventilation during filling is already realized by the cover plate.

[0025] The cover plates, rotors, and methods are further described below with reference to exemplary embodiments illustrated in the accompanying drawings. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 illustrates an embodiment of a rotor of an electric machine having at least one cover plate. [Diagram 2] FIG. 2 is a perspective view of the rotor shown in FIG. 1, partially assembled. [Diagram 3] FIG. 2 is a perspective view of the cover plate according to FIG. [Figure 4] FIG. 3 is a cross-sectional view of the rotor shown in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] In FIG. 1, a rotor 10 of an electric machine is shown with two cover plates 1. The rotor 10 is rotatable about a rotation axis A and has a laminated core 3. The cover plates 1 are arranged at the axial ends of the laminated core 3, respectively. The laminated core 3 is fixedly connected to a rotor shaft 14 having a shoulder 17 on which the laminated core 3 rests, one of the cover plates 1 being arranged between the shoulder 17 and the laminated core 3. The following description shows that only one of the cover plates 1 must have the configuration according to the invention, i.e. the cover plate 1 arranged between the shoulder 17 and the laminated core 3. The designations such as axial, radial and circumferential generally refer to the rotation axis A shown in FIG. 1.

[0028] Figure 2 shows the rotor according to figure 1 partially assembled. One of the cover plates 1 has been removed and the slightly visible perspective view shows the individual rotor laminations joined together to form the laminated core 3 and securely connected circumferentially to the rotor shaft 14. The laminated core 3 has a first recess 8 and a second recess 9, the first recess 8 being provided to accommodate a permanent magnet 11. The second recess 9 remains free and serves, for example, for ventilation of the rotor 1 during operation and for weight reduction.

[0029] When assembling the rotor 1, the permanent magnets 11 are inserted into cavities provided for this purpose in the first recesses 8 of the laminated core 3. The laminated core 3 is placed on the rotor shaft 14 with the inserted permanent magnets 11. Due to the fact that the rotor shaft 14 has a shoulder 17, it is not possible to insert the cover plate 1 at a later stage. The insertion can only take place before the laminated core 3 is attached to the rotor shaft 14. To fasten the magnets 11 of this assembly in the first recesses 8, the first recesses 8 are filled by overmolding with a hardening plastic (not shown), for example with a thermosetting resin. The adjacent areas of the magnets and the laminated core have a temperature of about 180 ° C so that the thermosetting resin is injectable. To avoid deformations and other unfavorable reactions of the laminated core 3 to an uneven temperature distribution, the entire assembly is brought to a constant temperature. The boundary condition of this process, in addition to the temperature, is to ensure the airtightness of the cavity to be filled. The pressure is increased to about 60 bar and the laminated core 3 is pressurized with a force of about 200 kN.

[0030] The thermosetting resin is injected into the first recess 8 from one side. Air that is present in the cavity exits the first recess 8 from the other side. A cover plate already positioned there may prevent the air from escaping, which may lead to undesirable air pockets. The cover plate 1 therefore has a ventilation duct 4 that fluidly connects at least the end 12 of the first recess 8 to the second recess 9, thereby allowing the first recess 8 to be ventilated during filling by venting the air through the ventilation duct 4 to the second recess 9.

[0031] In FIG. 3 the cover plate 1 is shown in a perspective view. The cover plate 1 has a contact surface 2 which, when mounted, rests against the laminated core 3 of the rotor 1 as shown in FIG. 1. The ventilation ducts 4 are formed in the form of grooves in the contact surface 2. In particular, the cover plate 1 can be a cast part, for example made of aluminium or plastic. Positioning means 16 are provided which determine a defined position of the cover plate 1 in the circumferential direction relative to the rotor 10. The ventilation ducts 4 are advantageously shaped and / or dimensioned in such a way that air can escape through them, whereby the hardenable plastic hardens in them before it leaves them. For this purpose the ventilation ducts can have a maximum extension in the direction perpendicular to the plane formed by the contact surfaces 2 of between 0.03 mm and 0.05 mm.

[0032] The arrangement of the ventilation duct 4 is such that the first recess 8 is fluidly connected to the second recess 9, as described above. To this end, the ventilation duct 4 in the illustrated embodiment has a shape adapted to the location of the first recess 8 and the second recess 9. The ventilation duct 4 does not have to be continuous. Each of a number of flow passage portions can connect adjacent first recesses 8 and second recesses 9. The ventilation duct 4 extends in a continuous or duct portion around the periphery of the cover plate 1.

[0033] In the illustrated exemplary embodiment, the ventilation duct 4 has several outer duct sections 5 and a series of inner duct sections 6, the outer duct sections 5 being arranged radially outward of the inner duct sections 6 with respect to the axis of rotation A in Fig. 1. The inner duct sections 6 and the outer duct sections 5 are arranged concentrically. One radial duct section 7 connects each one of the outer duct sections 5 to the inner duct sections 6.

[0034] In figure 4 the rotor according to figure 2 is shown in a cross-section, the cross-section being arranged perpendicular to the axis of rotation A through the cover plate 1 so that the ventilation duct 4 is visible. The rotor shaft 14 has counter-positioning means 15 which together with positioning means 16 determine the relative circumferential position of the cover plate 1 and the rotor shaft 14. In the illustrated exemplary embodiment the counter-positioning means 15 forms a feather key connection with the positioning means 16.

[0035] The laminated core 3 is visible behind the cover plate 1. This view shows that the first recess 8 is fluidly connected to the second recess 9 by the shape of the ventilation duct 4. In particular, the end 12 of the first recess 8, which is filled with plastic, at least partially axially overlaps the outer duct portion 5 and the continuous inner duct portion 6. The inner duct portion 6 also partially overlaps axially with the second recess 9, such that air escaping from the first recess 8 reaches the second recess 9 via the ventilation duct 4.

[0036] Ventilation duct 4 is 0.5 mm 2 Less than 0.2 mm, preferably 2 Less than 0.10 mm, particularly preferably 2 ~0.15mm 2 This advantageously prevents the plastic from entering the second recess 9 during injection, as the plastic is pre-hardened. Thus, once injection is complete, the plastic extends into the part of the ventilation duct 4.

[0037] In particular, the first dimension of the ventilation duct is significantly larger than the second dimension of the ventilation duct, so that the ventilation duct is particularly flat or particularly narrow. In the illustrated exemplary embodiment, the maximum extension of the ventilation duct 4 in the axial direction is significantly smaller than its width in the radial or circumferential direction. Such a flat ventilation duct 4 is easy to realize in a cast part. The width of the ventilation duct 4 is in particular at least 20 times larger than its height, preferably at least 50 times larger, particularly preferably about 60 times larger. [Explanation of symbols]

[0038] 1 Cover plate 2 Contact surface 3 Laminated Core 4. Ventilation duct 5 Outer duct section 6 Inner duct section 7 Radial duct section 8 First recess 9 Second recess 10 Rotor 11 Permanent magnets 12 End 14 rotor shaft 15 Opposing positioning means 16 Positioning means 17 Shoulder A Rotation Axis

Claims

1. A cover plate (1) for a rotor (10) of an electric machine, the cover plate having a contact surface (2) for abutting against a laminated core (3) of said rotor, at least one ventilation duct (4) in the form of a groove being formed in said contact surface (2).

2. 2. Cover plate according to claim 1, wherein the ventilation ducts have a maximum extension perpendicular to the plane formed by the contact surfaces (2) of less than 0.2 mm, preferably less than 0.1 mm, particularly preferably between 0.03 mm and 0.05 mm.

3. The ventilation duct (4) is 0.5 mm ２ Less than 0.2 mm, preferably ２ Less than 0.10 mm, particularly preferably ２ ~0.15mm ２ The cover plate of claim 1 having a cross-sectional area of

4. 4. The cover plate according to claim 3, wherein the first dimension of the ventilation duct (4) determining the cross-sectional area is substantially larger than the second dimension of the ventilation duct determining the cross-sectional area, in particular at least 20 times larger, preferably at least 50 times larger, particularly preferably about 60 times larger.

5. 2. A cover plate according to claim 1, wherein the ventilation ducts (4) in each case have at least one outer duct section (5), one inner duct section (6) and one radial duct section (7), the outer duct section being arranged further radially outward than the inner duct section and the outer duct section being connected to the inner duct section via the radial duct section.

6. 2. A cover plate according to claim 1, comprising a plurality of outer duct sections (5), each of which is connected via a radial duct section (7) to a continuously formed inner duct section (6).

7. 2. The cover plate of claim 1, further comprising positioning means (16) for fixing a defined circumferential position of the cover plate relative to the rotor (10).

8. 2. The cover plate according to claim 1, wherein the cover plate (1) is a cast part.

9. A rotor (10) for an electric machine, rotatable about a rotation axis (A) and having a laminated core (3), at least one cover plate (1) according to claim 1 being arranged at an axial end of said laminated core.

10. 10. The rotor according to claim 9, wherein the laminated core (3) has a first recess (8) and a second recess (9), the first recess being provided for accommodating a permanent magnet (11), and at least ends (12) of the first recess (8) and the second recess (9) being fluidly connected to the ventilation duct (4).

11. 11. A rotor according to claim 10, wherein the first recess (8) for embedding the permanent magnet (11) is filled with plastic, the plastic extending into a partial region of the ventilation duct (4).

12. 10. The rotor according to claim 9, wherein the laminated core (3) is fixedly connected to a rotor shaft (14), the rotor shaft (14) having opposing positioning means (15) which, together with the positioning means (16), determine the relative circumferential position of the cover plate (1) and the rotor shaft (14).

13. 13. A rotor according to claim 12, wherein the rotor shaft (14) has a shoulder (17) on which the laminated core (3) rests, and the cover plate (1) is arranged between the shoulder and the laminated core.

14. 10. The method for mounting a rotor (10) according to claim 9, wherein the cover plate (1) and the laminated core (3) are placed on a rotor shaft (14), a permanent magnet (11) is placed in a first recess (8) of the laminated core (3), the first recess (8) is filled with a plastic material to embed the permanent magnet in the first recess, and the first recess (8) is ventilated by exhausting air through the ventilation duct (4) into the second recess (9) while filling with the plastic material.

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