CN111656655B

CN111656655B - Method and device for producing a spoked rotor for an electric machine

Info

Publication number: CN111656655B
Application number: CN201980010117.9A
Authority: CN
Inventors: 蒂洛·施托普费尔
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2018-08-29
Filing date: 2019-07-22
Publication date: 2023-04-18
Anticipated expiration: 2039-07-22
Also published as: WO2020043229A1; CN111656655A; DE102018121062A1

Abstract

The invention relates to a method for producing a spoked rotor for an electric machine, wherein a hollow-cylindrical core arranged around a rotational axis is provided, the core having an inner circumferential surface on which a plurality of recesses for receiving permanent magnets in each case are arranged, and wherein the plurality of permanent magnets in each case are introduced individually into the recesses in the hollow-cylindrical core by a movement in a radial direction arranged perpendicularly to the rotational axis. The invention also relates to a device for producing a spoked rotor for an electric machine, comprising a holding device for holding a hollow-cylindrical core arranged around an axis of rotation, the core having an inner circumferential surface on which a plurality of recesses for respectively accommodating permanent magnets are arranged, and an introduction device for introducing the permanent magnets into the recesses of the hollow-cylindrical core by means of a movement in a radial direction arranged perpendicular to the axis of rotation.

Description

Method and device for producing a spoked rotor for an electric machine

Technical Field

The invention relates to a method for producing a spoked rotor of an electric machine, i.e. a rotor having magnets arranged in a spoked manner.

Background

A spoked rotor for an electrical machine usually has a core and a plurality of permanent magnets arranged spoked in the core. The permanent magnets are usually polarized alternately in opposite directions in the tangential direction, so that magnetic north poles alternate with magnetic south poles all the time in the circumferential direction of the spoked rotor. Tangentially between the permanent magnets, the core collects and directs the magnetic flux radially outward to the outer peripheral surface of the core, which is typically constructed as a stack of plates. In order to introduce the largest part of the magnetic flux into the air gap of the machine, the flux of magnetic losses through the connecting bridges of the individual poles should be minimal.

In manufacturing these spoke rotors, permanent magnets are installed at the core in a magnetized state. The disadvantage here is that the permanent magnet must be moved relative to the core. Because the permanent magnet and the core attract each other, significant frictional forces are generated. The surface of the core is particularly rough, in particular when the core is formed from stacked punched plates. Permanent magnets, in particular sintered permanent magnets, often require an anti-corrosion coating which can be damaged by friction. These permanent magnets with damaged corrosion protection coatings have a reduced service life.

DE 10 2011 115 454 A1 proposes a method for producing a spoke rotor, in which a non-magnetized, hard-magnetic material is connected to a section of a core and is magnetized after the connection. Although damage to the anti-corrosion measures on the permanent magnets and leakage of flux can be prevented in this way. However, the subsequent assembly of the individual segments, which are ferromagnetic and have tolerances, into a rotor is very costly.

Disclosure of Invention

On the basis of this, the object is to be able to produce a spoked rotor with a long service life and minimal leakage flux and to produce it in a production technology that is as simple as possible.

This object is achieved by a method for producing a spoked rotor for an electrical machine, wherein a hollow-cylindrical core arranged around a rotational axis is provided, the core having an inner circumferential surface on which a plurality of recesses for respectively accommodating permanent magnets are arranged, and wherein the plurality of permanent magnets are respectively introduced individually into the recesses in the hollow-cylindrical core by a movement in a radial direction arranged perpendicularly to the rotational axis.

According to the invention, the permanent magnets move in the radial direction and are in this case introduced into recesses at the inner circumferential surface of the core. Although the core and the permanent magnet will attract each other when introduced, so that friction occurs between the surface of the permanent magnet and the core. However, the displacement of the permanent magnet during the occurrence of friction corresponds to the permanent magnet stretching in the radial direction and the direction of movement running parallel to the individual plate, which is usually coated. As a result, the friction occurs only during the relatively short time of the radial introduction of the permanent magnet, as a result of which damage to the protective layer of the permanent magnet is reduced and the service life of the permanent magnet is increased.

Preferably, the hollow-cylindrical core is configured as a plate stack. The plate stack can have a plurality of stacked plates. The plates of the plate stack may have a substantially annular cross section, i.e. the material of the plates can completely surround the circumference of the hollow cylindrical core. Such a plate provides high mechanical strength, but enables a return path for the magnetic flux in the plate material, which at this time does not participate in the torque development by the electric machine. Alternatively, the plate can be segmented, wherein the plate is preferably designed as an arc-shaped section. Undesired return paths of the magnetic flux in the plate are prevented by such plates, but the core is mechanically twisted relatively slightly. It has been found to be advantageous if the hollow-cylindrical core is configured as a plate stack having plates of substantially annular cross section and plates configured as arc-shaped sections. By mixing different plate members in this way, a hollow cylindrical core having high mechanical strength and sufficient utility can be provided.

According to a preferred embodiment of the invention, the permanent magnet is formed before it is introduced into the recess, wherein a particularly square, magnetized, hard-magnetic mass is provided for forming the permanent magnet. The magnetization of the hard-magnetic masses in their unconnected state can be carried out with greater precision than in the state of connection to the core.

In this context, it is advantageous if the permanent magnets are formed separately in succession, wherein two successive permanent magnets each have opposite magnetic properties. The permanent magnets thus formed can then be introduced in succession into adjacent recesses in the core via introduction means, so that an arrangement of the permanent magnets in the core is achieved in which adjacent permanent magnets are magnetized in the tangential direction and the magnetization of adjacent permanent magnets alternates in the tangential direction. In this arrangement, magnetic south poles alternate with magnetic north poles in the circumferential direction of the core.

According to a preferred embodiment of the invention, the permanent magnet has a height and a length, and the height to length ratio is less than or equal to 0.1, preferably less than or equal to 0.07, particularly preferably less than or equal to 0.05. Here, the dimension of the permanent magnet along its magnetization direction, i.e., the direction in which the permanent magnet is arranged in the tangential or circumferential direction in the state of being introduced into the core, is referred to as the height of the permanent magnet. In this respect, the permanent magnets are configured as square magnets, wherein the magnetization direction extends perpendicular to the opposing maximum surface. Or in other words: the poles are located on the largest face. The length of the permanent magnet is understood to be the dimension of the permanent magnet which, in the inserted state into the core, extends in the axial direction of the hollow-cylindrical core.

An advantageous embodiment consists in that the permanent magnet is guided in the radial direction by the guide when it is introduced into the recess and is pressed into the recess by the punch. The guide enables the permanent magnet to be mechanically stable and resist undesired separation based on magnetic attraction. In this case, the respective permanent magnet is pressed into the respective recess by means of a punch. The guide is preferably directed towards the recess, for example the guide surface of the guide is arranged flush with one or more inner walls of the recess. The guide can have, for example, two press jaws which hold the permanent magnets in alignment with the respective recesses, while the punch presses the permanent magnets into the recesses. Particularly preferably, the pressure of the pressure clamp on the permanent magnet is adjustable.

According to a preferred embodiment, the permanent magnets are introduced into the recesses by means of an introduction device, and after the first permanent magnet is introduced into the first recess, the core is rotated relative to the introduction device or the introduction device is rotated relative to the core before the second permanent magnet is introduced into the second recess. By relative rotation of the introduction means and the core, the plurality of recesses of the core can efficiently insert the permanent magnets in sequence. The core is preferably held by holding means which are relatively rotatable with respect to the introducing means.

A preferred embodiment is to first introduce permanent magnets into all recesses of the hollow-cylindrical core and then to detect the magnetic field directly at the inner circumferential surface by means of a sensor, in particular a hall sensor, in order to detect defective permanent magnets or polarities. For detection, the sensor can be introduced into the hollow-cylindrical core. The core can rotate relative to the sensor, or the sensor can rotate relative to the core.

According to a preferred embodiment, the rotor carrier is connected to the hollow-cylindrical core in such a way that the outer circumferential surface of the rotor carrier abuts the inner circumferential surface of the hollow-cylindrical core. The connection of the core to the rotor support is preferably carried out after the permanent magnets have been introduced into the recesses in the core. By the connection with the rotor holder, the recess at the inner circumferential surface of the core can be closed, thereby ensuring that the permanent magnet accommodated in the recess does not accidentally slip out of the recess.

In this connection, it has proven advantageous to apply an adhesive on the outer circumferential surface of the rotor support before the rotor support is connected to the hollow-cylindrical core, the adhesive entering into the recess of the hollow-cylindrical core and fixing the permanent magnet when the rotor support is connected to the hollow-cylindrical core. The risk of the permanent magnet sliding in the recess can be reduced by means of the adhesive.

In order to achieve the object mentioned at the outset, an apparatus for producing a spoked rotor for an electrical machine is also proposed, which apparatus comprises a holding device for holding a hollow-cylindrical core arranged around an axis of rotation, which core has an inner circumferential surface on which a plurality of recesses for respectively accommodating permanent magnets are arranged, and an introduction device for introducing the permanent magnets into the recesses of the hollow-cylindrical core by means of a movement in a radial direction arranged perpendicularly to the axis of rotation.

The device achieves the same advantages as have been described in connection with the method according to the invention.

The holding device preferably has a plurality of housing sections, in particular two housing halves. The shell segments can have contact surfaces which match the outer circumferential surface of the hollow-cylindrical core and which contact the outer circumferential surface when the core is held. The holding device is preferably made of a non-ferromagnetic material, for example plastic, in particular hard plastic, so that no magnetic interaction with the core or the permanent magnet is to be feared.

According to a preferred embodiment of the invention, the device has a magnetization device for forming a permanent magnet, which magnetization device is provided for magnetizing a block which is in particular square and hard-magnetic. The magnetizing device can have a magnet input via which the hard-magnetic mass can be fed to the dispensing mechanism of the magnetizing device. The blocks can be individually fed into the magnetization tool of the magnetization device via the dispensing mechanism. The magnetizing means preferably comprise an electromagnet, the magnetic field of which is adjustable.

The introduction means are able to transport the permanent magnets from the magnetizing means into the corresponding recesses of the core.

Drawings

Further details and advantages of the invention shall be described below on the basis of embodiments shown in the drawings. In which is shown:

FIG. 1 shows a perspective view in partial cutaway of an embodiment of a spoked rotor;

fig. 2 shows a schematic cross-sectional view of the core of the spoked rotor according to fig. 1 along a first sectional plane;

fig. 3 shows a schematic cross-sectional view of the core of the spoke rotor according to fig. 1 along a second sectional plane;

fig. 4 shows a schematic view of an apparatus for manufacturing a spoked rotor;

fig. 5 shows a perspective cross-sectional view of a first embodiment of a holding device for holding a core when manufacturing a spoked rotor;

fig. 6 shows a perspective cross-sectional view of a second embodiment of a holding device for holding a core when manufacturing a spoked rotor;

FIG. 7 shows a schematic view of an embodiment of a magnetising apparatus;

FIG. 8 shows a cross-sectional view of one embodiment of an introducer device;

fig. 9 shows a perspective view of the introduction device according to fig. 8;

fig. 10 shows a cross-sectional view of a variant of the introduction device according to fig. 8;

fig. 11 and 12 show schematic views of an introduction device with permanent magnets to clearly illustrate the process of introducing permanent magnets into the notches;

fig. 13 shows a perspective cross-sectional view of an assembly apparatus for assembling a core with a rotor frame.

Detailed Description

Fig. 1 schematically shows an exemplary embodiment of a spoke rotor 1 produced by means of the method according to the invention. The spoked rotor 1 can be installed as a permanently excited rotor in an electrical machine, for example in a generator or an electric motor.

The spoked rotor 1 comprises a hollow cylindrical core 2, which is arranged around a rotation axis a. The core is constructed as a stack of plates. The core 3 has a substantially circular cross-section. A plurality of recesses 6, in which the permanent magnets 3 are respectively arranged, are provided on the inner circumferential surface 4 of the core. The permanent magnet 3 is of square design and has a length which corresponds substantially to the height of the hollow-cylindrical core. The permanent magnet also has a height H. The ratio of the height H to the length L is less than or equal to 0.1, preferably less than or equal to 0.07, particularly preferably less than or equal to 0.05. Here, the height H corresponds to the dimension of the permanent magnet 3 in the direction of magnetization of the permanent magnet, i.e., the direction of the magnetization axis thereof. The permanent magnets 3 are arranged in the core 2 such that the magnetization of the permanent magnets is oriented in the tangential direction. Furthermore, the permanent magnets 3 are arranged in such a way that they are alternately oppositely polarized, so that magnetic north poles and magnetic south poles always alternate in the circumferential direction of the spoke rotor. The core 2 concentrates the magnetic flux between the tangential directions of the permanent magnets 3 and guides the magnetic flux radially outward to the outer peripheral surface 5 of the core 3.

The rotor carrier 7 bears against the inner circumferential surface 4 of the core 2, which carries the core 2 and the permanent magnets 3. The rotor carrier 7 comprises a stop with an annular cross section, against which the core 2 bears. The core 2 and the rotor support 7 are connected to each other, in particular by means of adhesive.

The construction of the core 2 is described below on the basis of the schematic diagrams in fig. 2 and 3. The schematic representation in fig. 2 shows a schematic sectional view of the core 2 according to fig. 1 along a first sectional plane. In this sectional plane, the core 2 has a plate configured as an arc-shaped section 9. Between the individual arc segments 9, in each case a recess 10 is provided which on the one hand forms a recess for accommodating the permanent magnet 3 and on the other hand prevents the magnetic flux within the core 2 from closing undesirably in the illustrated sectional plane. Fig. 3 shows a schematic cross-sectional view of the core 2 along a second sectional plane. In the second sectional plane, an annular plate 12 is provided, which has a substantially annular cross section and the recess 6. The recesses 6 are each delimited by a connecting portion 11, which enables the magnetic flux within the sheet material to completely surround in the circumferential direction of the hollow-cylindrical core 2. The individual plates of the core 2 are electrically insulated from each other in the axial direction. In the plate of the core 2 there is also provided a hole 13, which is not filled. These holes are used to reduce weight and can be used to accommodate tools during manufacture. The core is made in a hybrid structure, combining the advantages of a segmented construction (fig. 2) with the advantages of a full section (fig. 3). The complete section is arranged here at regular intervals in the core and receives the magnetic short-circuit path, see fig. 1.

For the production of the spoked rotor 1, the method which will be explained in detail below can be used. Fig. 4 shows a schematic flow diagram of such a method for producing a spoked rotor 1 of an electrical machine. In the method, a hollow-cylindrical core 2 arranged around a rotational axis a is provided in a providing step 101, the core having an inner circumferential surface 4 on which a plurality of recesses 6 for respectively receiving permanent magnets 3 are arranged. In an introduction step 102, the permanent magnets 3 are introduced into the recesses 6 in the hollow-cylindrical core 2, see fig. 1, individually by a movement along a radial direction R arranged perpendicular to the axis of rotation a. Alternatively, in the checking step 103, the inner circumferential surface 4 of the core 2 can be detected by means of a sensor, in particular by means of a hall sensor, in order to detect a defective permanent magnet 3 or a polarity. Next, in a connecting step 104, the rotor support 7 is connected to the hollow-cylindrical core 2 in such a way that the outer circumferential surface of the rotor support 7 comes into contact with the inner circumferential surface 4 of the hollow-cylindrical core 2.

A corresponding apparatus for manufacturing such a spoke rotor 1 of an electric machine has a holding device 20 for holding a hollow-cylindrical core 2 arranged around a rotational axis. Fig. 5 shows an exemplary embodiment of such a holding device 20 for holding a hollow-cylindrical core 2 in a perspective sectional view. The retaining means 20 adjusts the ring so that it is stable and preferably capable of rotating. Furthermore, the core 2 may remain in the retaining means 20 during its transport to the different positions of the apparatus for manufacturing the spoked rotor 1. The retaining device 20 is preferably formed from a non-ferromagnetic material, for example from a hard plastic. The holding device 20 comprises two housing sections 21, only one of which is shown in fig. 5, which are formed as half-shells. The shell section accommodates the core 2 in a shape adapted to the outer diameter of the core and holds the core in the radial direction. A stop 22 with an abutment surface against which the core 2 abuts in the axial direction is located on the underside of the shell section. To accommodate the core 2, the shell segments 21 are moved towards each other, thereby fixedly enclosing the core 2.

As shown in fig. 6, the core can be loaded with a force F1 in the axial direction via the pressure piece 23. In this way, the respective plates of the core can be pressed together in the axial direction, thereby firmly holding the core 2 and clamping from all sides except the inner circumferential surface 4. The recess 6 remains accessible and the height tolerances of the plate stack are compensated.

Before the permanent magnet 3 is introduced into the recess 6, the permanent magnet 3 is formed by providing a square, magnetically hard block 3', wherein the block is magnetized by means of the magnetization device 30 shown in fig. 7. The magnetizing apparatus 30 has a magnet input part 31 configured according to the type of input hose. The hard magnetic mass 3' is transported via the magnet input 31 to the dispensing mechanism 32. The dispensing mechanism 32 enables the blocks 3' to be introduced individually into the magnetizing means 33 of the magnetizing means 30. The permanent magnets 3 are formed in the magnetizing tool 33 in succession, wherein two successive permanent magnets 3 have respectively opposite magnetic properties. The magnetized permanent magnet 3 falls from the magnetization tool 33 and is received and clamped by two non-magnetic holding grooves 41 of the lead-in device 40.

The introduction device 40 is designed such that the permanent magnet 3 is introduced into the recess 6 of the hollow-cylindrical core 2 by a movement along a radial direction R arranged perpendicularly to the axis of rotation a. The retaining groove 41 is part of a guide of the introduction device 40, which guide makes the permanent magnets 3 mechanically stable when introduced into the recess 6 and resists undesired separation from each other due to magnetic attraction forces, see fig. 8 to 12. For introducing the permanent magnets 3, the holding grooves 41 with the permanent magnets 3 run towards the recesses 6 in the core 2. The retaining groove 41 is loosened slightly and the permanent magnet 3 is guided by the punch 42 through the retaining groove 41 and pressed into the recess 6, see fig. 11 and 12.

As shown in fig. 10, the plunger 42 can be moved via a rotatably mounted lever 43, on which a force F2 acts.

After the introduction of the first permanent magnet 3 into the core 2, the core 2 is rotated relative to the introduction means 40 before the introduction of the second permanent magnet 3 into the second recess 6 of the core 2.

After all the recesses 6 of the core 2 have been inserted into the permanent magnets 3, the holding device 20 with the core 2 is transported to another position of the apparatus, in which a connection to the rotor holder 7 is made.

Before the connection to the rotor carrier 7, the probe with the hall sensor can be inserted into the inner diameter and the holding device 20 with the inserted core 2 can be rotated. This signal is compared with a theoretical signal, so that a permanent magnet 3 with the wrong polarity or incorrect magnetization is identified in advance and, if necessary, replaced.

Fig. 13 shows the mandrel 50, on which the rotor holder 7 is received. The rotor holder 7 is connected to the hollow-cylindrical core 2 by means of the mandrel 50 in such a way that the outer circumferential surface of the rotor holder 7 abuts the inner circumferential surface 4 of the hollow-cylindrical core 2. The rotor holder 7 received on the mandrel 50 is provided with an adhesive 14 in the surrounding region. The holding device 20 with the inserted core 2 is located exactly concentrically below the rotor support 7. The rotor support is introduced or pressed into the inner space of the core 2 from above. The adhesive 14 spreads and is squeezed into all gaps. Here, the adhesive also adheres to the permanent magnet 3 and prevents further movement of the permanent magnet. The rotor support 7 thus largely ensures the later roundness of the structure.

And finally releasing the retaining means 20. The mandrel 50 pulls the finished spoke rotor 1 upwards and brings it to the output. A balancing process may also be performed on the mandrel 50 depending on the curing time of the adhesive.

The above-described apparatus for manufacturing a spoked rotor 1 of an electric machine comprises a holding device 20 for holding a hollow cylindrical core 2 arranged around a rotation axis a, the core having an inner peripheral surface 4 on which a plurality of recesses 6 for respectively accommodating permanent magnets 3 are arranged, and an introduction device 40 for introducing the permanent magnets 3 into the recesses of the hollow cylindrical core 2 by means of a movement along a radial direction R arranged perpendicularly to the rotation axis a.

List of reference numerals

1. Spoke rotor

2. Hollow cylindrical core

3. Permanent magnet

4. Inner peripheral surface

5. Peripheral surface

6. Notch (S)

7. Rotor support

8. Stop part

9. Arc segment

10. Air gap

11. Connecting part

12. Annular plate

13. Hole(s)

14. Binder

20. Holding device

21. Shell segment

22. Stop part

23. Pressing block

30. Magnetizing device

31. Magnet input component

32. Dispensing mechanism

33. Magnetizing tool

40. Lead-in device

41. Holding groove

42. Punch head

43. Lever

50. Mandrel

101. Providing step

102. Introduction step

103. Checking step

104. Connecting step

Axis of rotation A

Force F1, F2

Height of H core

Length of L core

R radial direction

Claims

1. Method for producing a spoked rotor (1) of an electrical machine, wherein a hollow-cylindrical core (2) arranged around a rotational axis (A) is provided, having an inner circumferential surface (4) on which a plurality of recesses (6) are arranged for receiving the permanent magnets (3) in each case, and wherein the plurality of permanent magnets (3) in each case are introduced individually into the recesses (6) in the hollow-cylindrical core (2) by a movement in a radial direction (R) arranged perpendicularly to the rotational axis (A);

wherein the permanent magnet (3) is introduced into the recess (6) by means of an introduction device (40); and after introduction of the first permanent magnet (3) into the first recess (6) and before introduction of the second permanent magnet (3) into the second recess (6), the core (2) is rotated relative to the introduction means (40) or the introduction means (40) is rotated relative to the core (2).

2. Method according to claim 1, characterized in that the permanent magnet (3) is formed before the permanent magnet (3) is introduced into the recess (6), wherein a particularly square, magnetized, hard-magnetic block (3') is provided for forming the permanent magnet (3).

3. Method according to claim 2, characterized in that the formation of the permanent magnets (3) is carried out separately in succession, wherein two successive permanent magnets (3) each have opposite magnetic properties.

4. Method according to claim 1, characterized in that the permanent magnet (3) has a height (H) and a length (L) and the ratio of the height (H) to the length (L) is less than or equal to 0.1, preferably less than or equal to 0.07, particularly preferably less than or equal to 0.05.

5. Method according to claim 1, characterized in that the permanent magnet (3) is guided in the radial direction (R) by a guide (41) when introduced into the recess (6) and is pressed into the recess (6) by a punch (42).

6. Method according to claim 1, characterized in that a permanent magnet (3) is first introduced into all recesses (6) of the hollow-cylindrical core and then the magnetic field is detected directly at the inner circumferential surface (4) by means of a sensor, in particular by means of a hall sensor, in order to detect a defective permanent magnet (3).

7. Method according to claim 1, characterized in that a rotor support (7) is connected to the hollow-cylindrical core (2) in such a way that an outer circumferential surface of the rotor support (7) comes into contact with an inner circumferential surface (4) of the hollow-cylindrical core (2).

8. A method according to claim 7, characterized in that before the rotor holder (7) is connected with the hollow-cylindrical core (2), an adhesive (14) is applied on the outer circumferential surface of the rotor holder (7), which adhesive enters the recess (6) of the hollow-cylindrical core (2) and fixes the permanent magnet (3) when the rotor holder (7) is connected with the hollow-cylindrical core (2).

9. Apparatus for manufacturing a spoked rotor (1) of an electrical machine, characterized in that it comprises a holding device (20) for holding a hollow cylindrical core (2) arranged around a rotation axis (a), said core having an inner circumferential surface (4) on which a plurality of recesses (6) are arranged for respectively accommodating permanent magnets (3), and an introduction device (40) for introducing the permanent magnets (3) into the recesses (6) of the hollow cylindrical core (2) by means of a movement along a radial direction (R) arranged perpendicularly to the rotation axis (a);

wherein after introduction of a first permanent magnet (3) into a first recess (6) the core (2) is rotatable relative to the introduction means (40) or the introduction means (40) is rotatable relative to the core (2) before introduction of a second permanent magnet (3) into a second recess (6).