WO2021148088A1

WO2021148088A1 - Rotor, method for producing a rotor and electrical axial flux machine

Info

Publication number: WO2021148088A1
Application number: PCT/DE2021/100065
Authority: WO
Inventors: Holger Witt; Matthias Gramann
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2020-01-24
Filing date: 2021-01-21
Publication date: 2021-07-29
Also published as: DE102020101640A1

Abstract

The invention relates to a rotor (1) for an electrical axial flux machine (2) that can be operated as a motor and/or generator, said rotor comprising a support (3), a plurality of magnet elements (4) arranged against, on, or in the support (3) and running radially outwards, the magnet elements (4) being magnetized in a circumferential direction and being arranged individually or in groups in series around the circumference with alternating opposing magnetization directions. Also provided is a plurality of flux conduction elements (5) which conduct the magnetic flux and are arranged against, on, or in the support (3) and around the circumference, between the magnet elements (4). According to the invention, at least one of the flux conduction elements (5) arranged around the circumference between two respective magnet elements (4) is designed such that it does not completely fill the receiving space (6) formed between the two magnet elements (4), thereby forming defined gaps (7) which are devoid of flux conduction element material.

Description

Rotor, method of making a rotor and electrical

Axial flow machine

The present invention relates to a rotor for an electrical, motor-driven and / or generator-driven axial flux machine, comprising a carrier, a plurality of magnet elements arranged on, on or in the carrier, extending radially from the inside to the outside, and a plurality of, Flux guide elements which conduct the magnetic flux and are arranged on or in the carrier, circumferentially arranged between the magnetic elements. The invention also relates to a method for setting a rotor and an axial flow machine.

A rotor for an axial flux machine is already known from DE 102013218829 A1. In this rotor, the rotor laminations form a type of frame into which inlays are integrated. The rotor laminations have individual cutouts for both the magnets and the inlays.

Further structures of rotors for axial flux machines or of axial flux machines themselves are described, inter alia, by DE 102017 204434 A1, DE 102005053 119 A1, DE 102004038884 A1, DE 10 2015208 281 A1, DE 102017127 157 A1 or WO 2018 / 015293 A1.

The magnetic flux in an axial flux motor (electric motor) is axially directed in the air gap between the stator and rotor. A laminated rotor for high speeds and frequencies is layered in the axial direction. The axial magnetic flux has to overcome the adhesive layers, as a result of which the magnetic circuit experiences a shear (additional air gap) and loses its efficiency. This in turn causes the engine to lose power. For the axial magnetic flow, SMC (soft magnetic components / soft magnetic powder) is often used, since a 3D flow without significant eddy currents is possible here. For smaller rotors there is a homogeneous SMC rotor possible as long as the mechanical load does not exceed the low strength of the SMC.

The invention is based on the object of providing a rotor for an electrical machine, a method for producing a rotor and an electrical axial flux machine, as a result of which the use of magnetic flux conducting material can be further reduced. Expensive SMC material should advantageously be saved.

This object is achieved in each case by the totality of the features of the individual independent claims 1, 8 and 10. Preferred developments of the invention are defined in the subclaims.

A rotor according to the invention for an electrical, motor-driven and / or generator-driven axial flux machine comprises a carrier, a plurality of magnet elements arranged on, on or in the carrier, extending radially from the inside to the outside, and a plurality of on, on or in the carrier arranged circumferentially between the magnetic elements, the magnetic flux conducting flux guide elements. The magnet elements are designed to be magnetized in the circumferential direction and are arranged alternately one behind the other individually or in groups circumferentially with the opposite direction of magnetization. According to the invention, at least one of the flux guide elements arranged circumferentially between two magnet elements is designed such that it only incompletely fills the receiving space formed between two magnet elements, so that defined free spaces that are free of flux guide element material of the flux guide element are formed. This has the advantage that flux guiding material can be saved for the flux guiding elements.

The free spaces are advantageously dimensioned in such a way that the magnetic flux in the air gap, compared to a rotor without free space or with a total space between the magnetic elements completely filled with flux guide material, by a maximum of 20%, preferably by a maximum of 10%, particularly preferably by a maximum of 5 %, in particular by a maximum of 2%, better still by a maximum of 1%.

With regard to the SMC material used, a free space created according to the invention is preferably dimensioned such that it is at least 5%, in particular at least 10%, particularly preferably at least 15%, even better measures at least 20%, 25% or 30% of the total space between two adjacent magnetic elements. The recess in the SMC material should not exceed 45% of the total volume of the total space between the magnetic elements.

The free space or the recess particularly preferably measures at least 20% and a maximum of 40% of the total installation space. Overall, a material saving compared to a total space completely filled with flux guide material of at least 20% and an associated change in the magnetic field strength in the air gap of a maximum of 10% should be aimed for.

The total space between two adjacent magnet elements is determined by length x width x depth, the length being measured by the radial distance between the inner ring section and the outer ring section, over which the flux guide elements extend radially from the inside to the outside, and the width of the total space by the circumferential, radially from the inside to the outside increasing distance between two adjacent magnet elements is defined, and wherein the depth is essentially determined by the thickness of the rotor or, in the case of a rotor with a rear base plate, by the axial depth to the base plate. Put simply, the total space is the space that is filled by a flux guide element material that is flush with the thickness of the annular disk-like rotor on the front and rear and is pressed into the space between two adjacent magnet elements. If there is a floor, the depth would be reduced by the thickness of the floor. However, since every component of the rotor can be geometrically delimited by surfaces of almost any shape, the above description is only valid for simple and special arrangements. The rotor can have different thicknesses at each radius, and the magnet can also be designed freely in all dimensions. The recess (volume of the material saving) can also have dimensions that are changed in a radially dependent manner.

Among the different alternatives of an, on or in the carrier mentioned above, the following explanations are meant as examples: an: The carrier consists, for example, of an inner hub body, with the magnets and flux guide elements radially on the outside of the hub body are attached and or held radially on the hub body, for example by means of a ring. on: The carrier has a disc-shaped area or radially protruding struts or other protruding support elements on which or on which the magnetically active components are attached (e.g. gluing) in: The carrier and the magnetic guide elements are arranged similar to the figures.

An axial flux machine within the meaning of the invention is characterized in that the magnetic flux generated in the air gap between rotor and stator extends in the axial direction parallel to the axis of rotation of the electrical machine. In other words, the air gap is expanded in a plane that is perpendicular to the axis of rotation of the rotor.

The magnetic flux conducting material is preferably formed from iron powder or from a mixture with iron powder. SMC material is particularly preferably used.

In a particularly preferred embodiment of the carrier, this has an inner ring, via which the rotor can be connected to a shaft in a rotationally fixed manner, and an outer ring which delimits the rotor outward in the radial direction. The carrier can be formed between the inner ring and the outer ring with a bottom part via which the inner ring and the outer ring are connected to one another and which, together with the radial outer ring surface of the inner ring and the radial inner ring surface of the outer ring, provides a receiving space open in the direction of the air gap for receiving the magnetic elements and which forms the flux guide elements of the rotor. It is also possible to design the carrier as a hub construction which extends as far as the inner radius of the magnetic circuit and which is equipped with attached permanent magnets and flux guide pieces. A ring band or some other method (gluing, form fit) then holds the attached permanent magnets and flux guide pieces in position.

In another embodiment of a carrier, a carrier is provided without an outer ring and / or without a base part. The magnet elements and the flux guide elements can be held radially inward by gluing on the carrier. As an alternative or in addition to gluing, the magnetic elements and the flux guide elements can also mechanically pass through Claw elements, which are then supported by means of struts on the inner hub-like carrier body, are fixed.

According to an advantageous embodiment of the invention, it can be provided that the at least one flux guide element has a recess with an axial depth extending over at least a partial area of the radial extent of the flux guide element. The advantage of this configuration is that material recesses can be designed in a structurally simple manner.

Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the at least one flux guide element is constructed in several parts, in such a way that a recess is formed with an axial depth extending over the radial extent of the flux guide element. For this purpose, several rods of the magnetic flux conducting material, each with a rectangular cross section, can be introduced into the carrier or arranged therein. The advantageous effect of this embodiment is based on the fact that corresponding geometries of magnetic flux guide material can be built up within the carrier with a large number of smaller identical parts.

According to a further preferred further development of the invention, it can also be provided that the recess within the magnetic flux elements is stepped, viewed in the axial direction in cross section, such that it is deeper in the middle area between two magnet elements than in the two laterally adjacent areas of the Recess. The magnetic flux guide elements can be designed in one piece or in several pieces. It can thereby be achieved that further magnetic flux conducting material can be saved without causing negative effects in the functionality of the rotor.

The recesses formed can be designed differently and have different cross-sectional shapes. In addition to the cross-sectional shape shown here with a rectangular cross-section or a combination of several rectangles, other cross-sections, such as triangles, semicircles, trapezoids and the like, are conceivable. Furthermore, the invention can also be further developed in such a way that the carrier has, on its front side facing the air gap, an edge directed radially inward from its outer circumference and / or an edge directed radially outward from its inner ring part for the axial fixation of the flux guide elements and / or which has magnetic elements.

In a likewise preferred embodiment variant of the invention, it can also be provided that the carrier has an annular disk-shaped carrier plate on the bottom side, which has a contour inside the carrier for receiving the flux guide elements, which interacts with the free spaces of the flux guide elements in such a way that a torque-transmitting form fit is formed and the free spaces are preferably completely filled by the bottom contour of the carrier. This means that the free spaces in the magnetic flux guide elements can be replaced by more cost-effective materials on the one hand and that, on the other hand, improved torque transmission is ensured in a structurally simple manner through this form fit between the carrier and the magnetic flux guide material acting in the direction of rotation.

The object of the invention is also achieved by a method for manufacturing a rotor, the method comprising the following method steps:

- Provision of a carrier which advantageously has an annular disk-shaped carrier plate,

- Provision of magnetic elements and introduction of the magnetic elements on, on or in the carrier, as well as

Introducing flux guiding material into the receiving spaces formed between two magnetic elements within the carrier to form the flux guiding elements.

The introduction of flux guiding material is advantageously carried out by pressing in SMC material. Alternatively, however, iron powder or SMC material pressed in the form of a rod with a rectangular or square cross-section can also be used. The rods are then simply inserted into the carrier accordingly. A loss protection in the axial direction can be created for example by a locking ring which is to be mounted on the outside and / or inside of the carrier and which secures the rod elements in the axial direction against falling out of the carrier.

Finally, the object of the invention can also be achieved by an axial flux machine with a rotor designed according to the invention. The axial flux machine advantageously comprises a rotor with a carrier and with a multiplicity of magnet elements and with a multiplicity of flux guiding elements which conduct the magnetic flux and which are arranged on, on or in the carrier, at least one of the flux guiding elements arranged circumferentially between two magnet elements being designed in this way is that it only incompletely fills the receiving space formed between two magnetic elements, so that defined free spaces that are free of the flux guide element material are formed, as well as at least one first stator with a plurality of coil magnets, which is attached to a first axial rotor side to form a first Air gap is arranged, and which generates a magnetic field which extends substantially in the axial direction in the direction of the rotor. The axial flux machine is particularly preferably designed in an H arrangement and, in addition to two rotors, comprises a stator arranged centrally between these two rotors.

The invention is explained in more detail below with reference to figures without restricting the general inventive concept.

Show it:

Figure 1 shows an axial flow machine according to the prior art in

Perspective view in schematic representation, with a rotor arranged between two stators,

FIG. 2 shows a further axial flow machine according to the prior art in a perspective view in a schematic representation, in an H-arrangement, FIG. 3 shows a rotor according to the invention in three different perspective views, in a representation with partial section, in a schematic representation,

Figure 4 shows the course of the magnetic field lines for a developed (running in the circumferential direction) partial section through a motor segment, for a rotor according to the prior art,

Figure 5 shows the course of the magnetic field lines for a developed (running in the circumferential direction) partial section through a motor segment, for a rotor according to the invention, and

FIG. 6 shows a preferred embodiment of a magnetic flux element for a rotor according to the invention in two perspective views in a schematic representation.

FIG. 1 shows an axial flux machine according to the prior art in a perspective view in a schematic representation, with a rotor arranged between two stators in its basic structure. The axial flux machine 2 comprises a rotor 1, which is shown here schematically without its carrier parts but with magnet elements 4 and flux guide elements 5 alternating circumferentially. In the upper illustration, a first stator 11 is shown in a top view from the inside, so that the individual stator coils of the stator 11 can be clearly seen here. Advantageously, two adjacent stator coils are connected together, with a total of six adjacent stator coils resulting in three stator coil packs, each controlled offset by 120 angular degrees. If the first stator 11, in the illustration above, were folded down by 180 angular degrees and kept axially spaced apart from the rotor 1 with the formation of a first air gap 13, the uniform, compact axial flux machine would result in the assembled state. The lower illustration shows a top view of the remaining stator-rotor core, with the second stator 11, axially spaced apart by a second air gap 13, carrying the rotor 1. FIG. 2 shows a further axial flow machine 2 according to the prior art in a perspective view in a schematic representation, in an H-arrangement. A rotor 1 is arranged axially on both sides of a centrally arranged stator 6 with stator coils, each spaced apart by an air gap 7.

FIG. 3 shows a rotor according to the invention in three different perspective views, in a representation with partial section, in a schematic representation. From the lower representation of FIG. 3 and from FIGS. 5 and 6 it can be seen that the at least one flux guide element 5 has a recess 8 with axial depth extending over at least a portion of the radial extent of the flux guide element 5 to form a free space 7. The recess 8 is stepped in the axial direction in cross section, such that it is axially deeper in the middle area between two magnet elements 4 than in the two laterally adjacent areas of the recess 8. At the top left, the rotor 1 is fully equipped with magnet elements 4 and shown with flux guide elements. In the view to the right, some areas are not equipped with magnetic elements and flux guide elements, so that the contouring of the carrier base of the carrier 3, which interacts with the flux guide elements 5 in a form-fitting manner via their recesses 8 and transmits torque, can be seen. The free spaces 7 are completely filled by the contour of the carrier 3 on the bottom side. The flux guiding elements 5 shown here are in one piece and preferably designed as flux guiding elements 5 made from pressed SMC material.

FIG. 4 shows the course of the magnetic field lines 1 for a developed partial section (running in the circumferential direction) through a motor segment for a rotor according to the prior art. The magnetic field lines are shown as they run within the stator 11, within the air gap 13 and within the rotor 1 of such an axial flux machine 2. It can be clearly seen here that there are regions of flux guide material within the flux guide elements 5 which are essentially without magnetic field lines or in which no magnetic flux is formed. According to the invention, these material areas have been left out, as can be seen from the exemplary embodiment according to the invention. In analogy to FIG. 4, FIG. 5 shows the course of the magnetic field lines for a developed partial section (running in the circumferential direction) through a motor segment for a rotor according to the invention. Significant parts of the flux guiding material were consciously saved here and replaced or filled in by appropriately shaped parts of the base plate of the carrier 3.

In FIG. 6, a preferred embodiment of a magnetic flux element 5 for a rotor 1 according to the invention is shown in two perspective views in a schematic representation as it was installed in the rotor 1, as it is shown in FIG. The magnetic flux guide element 5 is configured in the shape of a circular ring segment and is configured with radially extending recesses 8 on its side facing the base plate of the carrier 3 or on its side facing away from the air gap 13. The recesses 8 are widened circumferentially in both directions in a step-like manner, the axial thickness of the flux guide element 5 being greater in the widened lateral areas than in the central area of the recess 8.

The invention is not limited to the embodiments shown in the figures. The above description is therefore not to be regarded as restrictive, but rather as explanatory. The following patent claims are to be understood in such a way that a named feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. If the patent claims and the above description define “first” and “second” features, this designation serves to distinguish between two features of the same type without defining a ranking. Reference list

1 rotor

2 axial flow machine 3 carriers

4 magnetic element

5 flux guide element

6 recording room

7 Free space 8 Recess 9 Front

11 stator

12 coil magnet

13 air gap

Claims

Expectations

1. A rotor (1) for an electrical, motor-driven and / or generator-driven axial flux machine (2), comprising

- a carrier (3),

- A plurality of magnet elements (4) arranged on or in the carrier (3) and extending radially from the inside to the outside, the magnet elements (4) being magnetized in the circumferential direction and being arranged individually or in groups circumferentially alternately with opposite magnetization directions are,

- and a plurality of flux guide elements (5) which conduct the magnetic flux and which are arranged on or in the carrier (3) circumferentially between the magnetic elements (4), characterized in that at least one of the flux guide elements (5) are arranged circumferentially between two magnetic elements (4) Flux guide elements (5) is designed in such a way that it only incompletely fills the receiving space (6) formed between two magnet elements (4) within the carrier (3), so that defined free spaces (7) which are free of flux guide element material of the flux guide element (5) , are formed.

2. Rotor (1) according to claim 1, characterized in that the at least one flux guide element (5) to form a free space (7) has a recess (8) with axial depth extending over at least a portion of the radial extent of the flux guide element (5) having.

3. rotor (1) according to claim 2, characterized in that the recess (8) is stepped in the axial direction, such that it is deeper in the middle area between two magnetic elements (4) than in the two laterally adjacent areas of the Recess (8).

4. rotor (1) according to claim 1, characterized in that the at least one flux guide element (5) is constructed in several parts, in such a way that a recess (8) extending over the radial extent of the flux guide element (5) with axial depth is formed to form a free space (7).

5. rotor (1) according to claim 4, characterized in that the recess (8) is stepped, such that it is formed deeper in the middle area between two magnetic elements (4) in the axial direction than in the two laterally adjacent areas of the Recess (8).

6. Rotor (1) according to one of the preceding claims, characterized in that the carrier (3) on its front side (9) facing the air gap (13) has a circumferentially directed radially inward from its outer circumference and / or circumferentially from its inner one Has ring part radially outwardly facing edge for axial fixation of the flux guide elements (5) and / or the magnetic elements (4).

7. rotor (1) according to any one of the preceding claims, characterized in that the carrier (3) on the bottom side has an annular disk-shaped carrier plate which has a contour in the interior of the carrier (3) for receiving the flux guide elements (5), which with the free spaces (7) of the flux guiding elements (5) interacts in such a way that a torque-transmitting form fit is formed and the free spaces (7) are preferably completely filled by the bottom contour of the carrier (3).

8. A method for producing a rotor (1), in particular a rotor (1) according to one of the preceding claims, comprising the following method steps:

- Provision of a carrier (3),

- Provision of magnetic elements (4) and introduction of the magnetic elements (4) on, on or in the carrier (3), - Introducing flux guiding material into the receiving spaces (6) formed between two magnetic elements (4) to form the flux guiding elements (5).

9. The method according to claim 8, characterized in that the introduction of flux guide material takes place by pressing in SMC material.

10. Motor-driven and / or generator-driven axial flux machine (2), characterized in that the axial flux machine (2) has a rotor (1) according to one of the preceding claims 1-7, the axial flux machine (2) in particular comprises:

- A rotor (1) with a carrier (3) and with a plurality of magnetic elements (4) and with a plurality of the magnetic flux-conducting flux guide elements (5) which are arranged on, on or in the carrier (3), wherein at least one of the flux guide elements (5) arranged circumferentially between two magnet elements (4) is designed in such a way that it only incompletely fills the receiving space (6) formed between two magnet elements (4), so that defined free spaces (7) which are free of the flux guide material of the flux guide element (5) are formed, as well as

- A first stator (11) with a plurality of coil magnets (12), which is arranged on a first axial rotor side with the formation of a first air gap (13), and which generates a magnetic field which is essentially in the axial direction in the direction of the rotor ( 1) extends.