Cover plate for rotor, rotor and method for mounting rotor

Abstract

A cover plate for a rotor of an electric machine, the cover plate having a contact surface intended to be placed against a laminated core of the rotor; the invention relates to a rotor of an electric machine, said rotor being 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; the invention relates to a rotor and to a method for installing a rotor, in which a cover plate and a laminated core are arranged on a rotor shaft, in which permanent magnets are arranged in first recesses of the laminated core, and in which the recesses are filled with plastic in order to embed the permanent magnets in the first recesses.

Description

Technical Field

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

[0002] Such electric machines are known in the prior art. Such electric machines comprise a stator and at least one rotor which is rotatable relative to the stator about a rotation axis.

[0003] DE 102020128552 A1 relates to a rotor for a permanent magnet synchronous motor, which has a laminated core with recesses in which corresponding permanent magnets are accommodated. The recess has a first end section that is closer to the axis of rotation of the rotor than the second end section. In recesses that are adjacent to each other and whose first end sections are closer to each other in the circumferential direction of the rotor than the second end sections, the permanent magnets are arranged in such a way that the magnetic north poles N of the permanent magnets face each other. The rotor arranged in such a permanent excitation synchronous motor has a clamping disk or a cover disk, between which the laminated cores are pressed against each other. Drill holes can be made in multiple positions in these clamping disks. By providing corresponding drill holes at one or more of these positions, the rotor can be balanced or the imbalance in the rotation of the rotor can be eliminated.

[0004] DE 19915664 A1 discloses an electric machine having a stator and a rotor having at least one laminated core, the at least one laminated core having the following features: at least two different laminate cutouts of the laminated core, the laminated core of at least one laminate cutout being provided with means which enable radial fixation of the laminated core, in particular when the individual laminated cores are assembled axially. The laminated core of the rotor has recesses for permanent magnets, wherein the permanent magnets can be fixed by inserting a hardenable compound. Summary of the invention

[0005] An object may be to improve the method for assembling a rotor.

[0006] 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.

[0007] A cover plate of a rotor of an electrical machine has a contact surface which is intended to be placed against a laminated core of the rotor, at least one ventilation channel being formed in the form of a groove in the contact surface.

[0008] When assembling a rotor for a permanent magnet synchronous motor with integrated permanent magnets (IPMSM), the permanent magnets are inserted into cavities provided for this purpose in the laminated core. The laminated core is arranged on a rotor shaft with the inserted permanent magnets, which has a shoulder against which the laminated core is supported. The rotor shaft has an axis of rotation. References to the axial direction, radial direction and circumferential direction generally refer to this axis of rotation. Cover plates are arranged at the two axial ends of the laminated core, which cover plates are used, for example, to compensate for imbalances at the ends of the rotor assembly by drilling holes in the cover plates. These cover plates are therefore also called balancing washers or compensation disks. For rotor shafts with shoulders, it is not possible to refit one of the cover plates. This can only be done before the laminated core is mounted on the rotor shaft. In order to embed the magnets, they are overmolded with a curable plastic. Air must escape from the cavity, which is hindered by the cover plates already in place. Therefore, according to the invention, the cover plates have ventilation channels through which air can advantageously escape. Ventilation channels in the form of grooves in the contact surface, which lies against the laminated core, allow air to be discharged from the cavities occupied by the permanent magnets into other cavities of the laminated core that remain unoccupied.

[0009] According to an embodiment, provision is made for the ventilation channel to be shaped and / or dimensioned such that air can escape through the ventilation channel, wherein the curable plastic hardens in the ventilation channel before the curable plastic can escape from the ventilation channel. For this purpose, the ventilation channel may have a maximum extension of less than 0.2 mm, preferably less than 0.1 mm and particularly preferably between 0.03 mm and 0.05 mm in a direction perpendicular to the plane formed by the contact surfaces. The direction perpendicular to the plane formed by the contact surfaces corresponds to the axial direction. This means that the ventilation channel does not extend beyond its maximum axial extension into the cover plate. In order to ensure that the curable plastic hardens, it may be sufficient for the ventilation channel to have a specified maximum extension in the section.

[0010] According to an embodiment, the ventilation channel can have a plurality of channel sections, which do not necessarily have to be connected.The ventilation channel can extend continuously or interruptedly around the circumference of the cover plate.

[0011] According to a further embodiment, it is provided that the ventilation channel has a diameter of less than 0.5 mm 2 , preferably less than 0.2mm 2 And particularly preferably at 0.10 mm 2 and 0.15mm 2The cross-sectional area between. In addition, the first dimension of the ventilation channel that determines the cross-sectional area can be significantly larger than the second dimension of the ventilation channel that determines the cross-sectional area, in particular, the second dimension is at least 20 times larger, preferably at least 50 times, and particularly preferably about 60 times. The size and shape of the ventilation channel allow the discharge of air. The curable plastic hardens quickly in the ventilation channel designed in this way, closes the ventilation channel, and therefore advantageously does not enter the unoccupied cavity of the laminated core. The first dimension of the ventilation channel that determines the cross-sectional area can be its width transverse to the axis of rotation. The second dimension of the ventilation channel that determines the cross-sectional area can be its extension in the direction perpendicular to the plane formed by the contact surface, which extension can also be referred to as axial extension. In the case of a rectangular cross section, the first dimension that determines the cross-sectional area is the longer side of the rectangle, and the second dimension that determines the cross-sectional area is the shorter side of the rectangle. The longer side can be, for example, 3mm long, and the shorter side is, for example, 0.05mm long. The cross-sectional area can have other shapes, such as a semi-oval or semi-elliptical. 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.

[0012] Depending on the position of the cavity in the laminated core, the shape of the ventilation channel can be adapted to achieve the described ventilation. For example, the ventilation channel can respectively have at least one outer channel segment, one inner channel segment and one radial channel segment, wherein the outer channel segment is arranged further outwards than the inner channel segment in the radial direction, and wherein the outer channel segment is connected to the inner channel segment via a radial channel segment. In particular, this allows end segments of cavities for permanent magnets having different radial distances to the axis of rotation to be connected to the ventilation channel. Since the magnets of each pole are usually arranged in pairs and in a V-shape with respect to each other, the end segments of the cavities for permanent magnets have different radial distances to the axis of rotation.

[0013] The inner channel segment and / or the outer channel segment may be manufactured to be continuous in the circumferential direction. In addition, a plurality of outer channel segments may be provided, each of which is connected to a continuous inner channel segment via a radial channel segment.

[0014] According to a further embodiment, a positioning device is provided which determines a defined position of the cover plate relative to the rotor in the circumferential direction.

[0015] According to a further embodiment, it is provided that the cover plate is a cast part.

[0016] A further subject matter of the present application relates to a rotor of an electric machine, wherein the rotor is rotatable about an axis of rotation and has a laminated core, wherein at least one of the cover plates is designed as described above and is arranged at an axial end of the laminated core.

[0017] According to an embodiment, it is provided that the laminated core has a first recess and a second recess, wherein the first recess is provided for accommodating the permanent magnet.

[0018] According to a further embodiment, it is provided that at least an end section of the first recess and the second recess are fluidically connected to the ventilation channel.

[0019] According to a further embodiment, the first recess provided for embedding the permanent magnet is filled with a curable plastic, wherein the plastic extends into a partial region of the ventilation channel.

[0020] According to a further embodiment, provision is made that the laminated core is fixedly connected to a rotor shaft, which has a counter-positioning device which, together with the positioning device, determines the relative position of the cover plate and the rotor shaft in the circumferential direction.

[0021] According to a further embodiment, it is provided that the rotor shaft has a shoulder against which the laminated core is supported, wherein the cover plate is arranged between the shoulder and the laminated core.

[0022] A further object of the present application relates to a method for assembling the above-mentioned rotor, wherein a cover plate and a laminated core are arranged on a rotor shaft, wherein a permanent magnet is arranged in a first recess of the laminated core, wherein the first recess is filled with a curable plastic in order to embed the permanent magnet in the first recess, wherein the first recess is ventilated during the filling with plastic by discharging air through a ventilation channel into a second recess.

[0023] The risk of plastic getting between the laminations of the laminated core or even escaping to the outside of the laminated core is advantageously reduced. A quality check can be performed visually from the unsealed side of the laminated core via the second recess. This allows identification of whether plastic has penetrated the second recess. From a cost point of view, the cover plate can be cast without complicated post-processing. The tool for filling the first recess can advantageously be simplified, since the function of ventilation during filling is already fulfilled by the cover plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The cover plate, the rotor and the method are further illustrated below with reference to the exemplary embodiments shown in the accompanying drawings. In the drawings: Figure 1 An embodiment of a rotor of an electric machine having at least one cover plate is shown; Figure 2 Shown partially assembled as Figure 1 A perspective view of the rotor shown in ; Figure 3 Show according to Figure 1 A perspective view of a cover plate; Figure 4 Shown as Figure 2 A cross-sectional view of a rotor is shown in FIG. DETAILED DESCRIPTION

[0025] exist Figure 1 In the figure, a rotor 10 of an electric machine with two cover plates 1 is shown. The rotor 10 is rotatable about an axis of rotation A and has a laminated core 3. The cover plates 1 are each arranged at an axial end of the laminated core 3. The laminated core 3 is fixedly connected to a rotor shaft 14, which has a shoulder 17, against which the laminated core 3 is supported, and one of the cover plates 1 is arranged between the shoulder 17 and the laminated core 3. The following statements show that only one of the cover plates 1 must have a configuration according to the invention, i.e. the cover plate 1 arranged between the shoulder 17 and the laminated core 3. Detailed descriptions such as the axial direction, the radial direction and the circumferential direction generally refer to the following. Figure 1 The axis of rotation A is shown in FIG.

[0026] Figure 2 Shown partially assembled according to Figure 1 One of the cover plates 1 is removed and a slightly perspective view reveals that the individual rotor laminations are joined together to form a laminated core 3 and are connected in a form-fitting manner in the circumferential direction to the rotor shaft 14. The laminated core 3 has a first recess 8 and a second recess 9, wherein the first recess 8 is provided to accommodate a permanent magnet 11. The second recess 9 remains unoccupied and serves, for example, for ventilation and weight reduction of the rotor 1 during operation.

[0027] When assembling the rotor 1, the permanent magnet 11 is inserted into the cavity provided for this purpose in the first recess 8 in the laminated core 3. The laminated core 3 is arranged on the rotor shaft 14 together with the inserted permanent magnet 11. Since the rotor shaft 14 has a shoulder 17, it is not possible to insert the cover plate 1 at a later stage. This can only be done before the laminated core 3 is mounted on the rotor shaft 14. In order to fasten the magnet 11 in the assembly in the first recess 8, the first recess 8 is filled with a curable plastic (not shown), for example by overmolding with a thermoset. The magnet and the adjacent area of ​​the laminated core have a temperature of about 180°C to allow the injection of the thermoset. In order to avoid deformation of the laminated core 3 and other adverse reactions to the uneven temperature distribution, the entire assembly is brought to a constant temperature. In addition to the temperature, the boundary conditions of the process also ensure the tightness of the cavity to be filled. A pressure of about 60 bar is established, and the laminated core 3 is pressed together with a force of about 200 kN.

[0028] The thermoset is injected into the first recess 8 from one side. The air in the cavity leaves the first recess 8 on the opposite side. The cover plate already positioned there prevents the air from escaping, which could lead to unwanted air pockets. Therefore, the cover plate 1 has a ventilation channel 4 which fluidically connects at least the end section 12 of the first recess 8 with the second recess 9, so that the first recess 8 can be ventilated during filling by discharging air via the ventilation channel 4 into the second recess 9.

[0029] exist Figure 3In FIG. 1 , a cover plate 1 is shown in a perspective view. The cover plate 1 has a contact surface 2 which, when mounted, rests against a laminated core 3 of the rotor 1 , as shown in FIG. Figure 1 . The ventilation channel 4 is formed in the contact surface 2 in the form of a groove. In particular, the cover plate 1 can be a casting, for example made of aluminum or plastic. Positioning means 16 are provided, which determine a defined position of the cover plate 1 relative to the rotor 10 in the circumferential direction. The ventilation channel 4 is advantageously shaped and / or dimensioned so that air can escape through the ventilation channel 4, whereby the curable plastic solidifies in the ventilation channel 4 before it leaves the ventilation channel 4. For this purpose, the ventilation channel can have a maximum extension of between 0.03 mm and 0.05 mm in a direction perpendicular to the plane formed by the contact surface 2.

[0030] The arrangement of the ventilation channel 4 is such that the first recess 8 is fluidly connected to the second recess 9, as described above. For this purpose, the ventilation channel 4 in the illustrated embodiment has a shape suitable for the position of the first recess 8 and the second recess 9. The ventilation channel 4 does not necessarily have to be continuous. A plurality of channel sections may each connect adjacent first recesses 8 and second recesses 9. The ventilation channel 4 extends continuously around the periphery of the cover plate 1 or in channel sections.

[0031] In the exemplary embodiment shown in the figure, the ventilation channel 4 has several outer channel sections 5 and a continuous inner channel section 6. The outer channel sections 5 are arranged in a radial direction relative to the inner channel section 6. Figure 1 The rotation axis A in the inner channel section 6 is arranged further outward than the inner channel section 6. The inner channel section 6 and the outer channel section 5 are arranged on concentric circles. One radial channel section 7 connects one of the outer channel sections 5 to the inner channel section 6, respectively.

[0032] exist Figure 4 In the cross-sectional view, the Figure 2 , wherein the section is arranged perpendicularly to the rotation axis A through the cover plate 1 so that the ventilation channel 4 is visible. The rotor shaft 14 has a counter-positioning device 15, which together with the positioning device 16 determines the relative position of the cover plate 1 and the rotor shaft 14 in the circumferential direction. In the exemplary embodiment shown in the figure, the counter-positioning device 15 and the positioning device 16 form a sliding key connection.

[0033] The laminated core 3 is visible behind the cover plate 1. This view shows that, due to the shape of the ventilation channel 4, the first recess 8 is fluidically connected to the second recess 9. In particular, the end section 12 of the first recess 8 filled with plastic at least partially overlaps axially with the outer channel section 5 and the continuous inner channel section 6. The inner channel section 6 also partially overlaps axially with the second recess 9, so that the air escaping from the first recess 8 reaches the second recess 9 via the ventilation channel 4.

[0034] The ventilation channel 4 may have a thickness less than 0.5 mm.2 , preferably less than 0.2mm 2 , and particularly preferably at 0.10 mm 2 and 0.15mm 2 This advantageously prevents the plastic from entering the second recess 9 during injection because it hardens in advance. Once the injection is complete, the plastic thus extends into the portion of the ventilation channel 4.

[0035] In particular, the first dimension of the ventilation channel is significantly greater than the second dimension of the ventilation channel, so that the ventilation channel is particularly flat or particularly narrow. In the exemplary embodiment depicted, the maximum extension of the ventilation channel 4 in the axial direction is significantly smaller than its width in the radial or circumferential direction. Such a flat ventilation channel 4 is easy to implement in a casting. The width of the ventilation channel 4 is in particular at least 20 times, preferably at least 50 times, and particularly preferably about 60 times its height.

[0036] Reference numerals list 1 Cover 2Contact surface 3-layer core 4 ventilation channels 5. External channel section 6 Inner channel section 7 Radial channel section 8 first recess 9 second recess 10 rotors 11 permanent magnet 12 End section 14 Rotor shaft 15. Reverse positioning device 16 Positioning device 17 Shoulders A. Axis of rotation.

Claims

1. A cover plate (1) of a rotor (10) of an electric machine, the cover plate having a contact surface (2) for bearing against a laminated core (3) of the rotor, wherein: At least one ventilation channel (4) in the form of a groove is formed in the contact surface (2).

2. The cover plate according to claim 1, wherein: The ventilation channel has a maximum extension in a direction perpendicular to the plane formed by the contact surface (2) of less than 0.2 mm, preferably less than 0.1 mm and particularly preferably between 0.03 mm and 0.05 mm.

3. The cover plate according to claim 1, wherein: The ventilation channel (4) has a thickness of less than 0.5 mm. 2 , preferably less than 0.2mm 2 , particularly preferably at 0.10 mm 2 and 0.15mm 2 The cross-sectional area between.

4. The cover plate according to claim 3, wherein: A first dimension of the ventilation channel (4) determining the cross-sectional area is significantly larger than a second dimension of the ventilation channel determining the cross-sectional area, in particular at least 20 times, preferably at least 50 times, and particularly preferably approximately 60 times, the second dimension.

5. The cover plate according to claim 1, wherein: The ventilation channel (4) has in each case at least one outer channel section (5), one inner channel section (6) and one radial channel section (7), wherein the outer channel section is arranged further outwards than the inner channel section in a radial direction and wherein the outer channel section is connected to the inner channel section via the radial channel section.

6. The cover plate according to claim 1, wherein: A plurality of outer channel segments (5) are provided, each of which is connected to a continuously formed inner channel segment (6) via a radial channel segment (7).

7. The cover plate according to claim 1, wherein: A positioning device (16) is provided, wherein the positioning device (16) fixes a defined position of the cover plate relative to the rotor (10) in a circumferential direction.

8. The cover plate according to claim 1, wherein: The cover plate (1) is a casting.

9. A rotor (10) of an electric motor, wherein: The rotor is rotatable about an axis of rotation (A) and has a laminated core (3), wherein at least one cover plate (1) according to claim 1 is arranged at an axial end of the laminated core.

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), at least an end section (12) of the first recess (8) and the second recess (9) being fluidically connected to the ventilation channel (4).

11. The rotor according to claim 10, wherein: The first recess (8) for embedding the permanent magnet (11) is filled with a plastic which extends into a partial region of the ventilation channel (4).

12. The rotor according to claim 9, wherein: The laminated core (3) is fixedly connected to a rotor shaft (14), wherein the rotor shaft (14) has a counter-positioning device (15), which together with the positioning device (16) determines the relative position of the cover plate (1) and the rotor shaft (14) in the circumferential direction.

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

14. A method for installing a rotor (10) according to claim 9, wherein: The cover plate (1) and the laminated core (3) are arranged on a rotor shaft (14), a permanent magnet (11) being arranged in a first recess (8) of the laminated core (3), wherein the first recess (8) is filled with a plastic material in order to embed the permanent magnet in the first recess, wherein during the filling with the plastic material, the first recess is ventilated by discharging air through the ventilation channel (4) into the second recess (9).

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