Electric drive having a toroidal coil carrier

Abstract

An electric drive comprises a stator (2) and a rotor (1) and a plurality of coils of a winding (3). The stator (2) has a toroidal coil carrier (21), wherein the cross-sectional area of the toroidal coil carrier (21) has the shape of an ellipse, more particularly a circle. The coils of the winding (3) are wound around sections (215) of the toroidal coil carrier (21).

Description

[0001] Electric drive with toroidal coil carrier

[0002] Field of the invention

[0003] The invention relates to an electric drive with a stator and a rotor. This formulation particularly encompasses the case of a radial flux machine with exactly one stator and exactly one rotor, and especially the case of an axial flux machine with two stators and one rotor. In addition, a plurality of coils is present.

[0004] background

[0005] An electric drive is an electrical machine that converts electrical power into mechanical power. Conductor coils carrying current generate magnetic fields, whose mutual forces of attraction and repulsion are converted into motion. An internal rotor motor consists of a stationary outer part and a rotating inner part. These parts are called the stator and rotor.

[0006] Electric motors are used in industries such as the packaging and food industries, robotics, medical technology and medical aids, and mobility, such as electric bicycles, small vehicles and small aircraft.

[0007] Conventionally, rectangular tooth structures with side lengths li and I2 are used for stator geometry, particularly for tooth-wound coil windings, where li is usually much larger than I2. The side length li is considered the torque-generating winding, and the side length I2 is considered the undesired winding head. On the one hand, the change in the magnetic flux and thus also its amplitude should be maximized, and on the other, current heat losses in the winding should be minimized.

[0008] Description of the invention

[0009] The task is to provide an electric drive which has a physically and mathematically optimized winding geometry.

[0010] This problem is solved by the subject matter of the independent claim. Accordingly, an electric drive comprises a stator and a rotor. The stator is stationary and the rotor moves. The rotor rotates the drive shaft. The electric drive comprises a plurality of turns of a winding wire wound into coils. The winding wire usually consists of a copper wire, in particular an enameled copper wire.

[0011] The electric drive comprises a toroidal coil former, with the coils of the winding wire wound around sections of the toroidal coil former and supported by it. The terms toroidal coil former or toroidal body refer to a body of revolution with a hole in the center. The axis of rotation passes through the hole and does not cross the body of revolution. Any cross-sectional area can be rotated, e.g. a square. If a cross-sectional area in the shape of a circle is rotated, the toroidal body is called a "torus". The cross-sectional area of ​​the toroidal coil former has the shape of an ellipse, in particular a circle.

[0012] The application of coils around "sections" of the toroidal coil carrier means that coils are not present along the entire rotation range, but only in sections.

[0013] A circle as a cross-sectional area has the largest surface area with the smallest possible circumference of all geometric 2D shapes. The length of the enclosing wire is thereby minimized. Consequently, the current heat losses in the winding wire, which is wound in a circle around the toroidal coil former, are also minimized. This is because the level of current heat losses is a function of the length of the winding wire. If the cross-sectional area is designed as an ellipse rather than a circle, the geometry is not optimal, but still better than with rectangular tooth structures in conventional electric drives.

[0014] The stator advantageously has a laminar structure with a plurality of laminations. The coils are wound between the laminations around the sections of the toroidal coil carrier. In particular, the toroidal coil carrier and the laminar structure are designed together to form a stator. For larger stator geometries, the stator can be assembled and glued from individual segments or from a plurality of sections. Supplementing the toroidal coil carrier with a laminar structure enables the use of conventional rotor structures. These can be either axial flux rotors or radial flux rotors. Without a laminar structure, the electric drive described could only be manufactured with immense production effort.

[0015] In particular, the laminations extend in the direction of the toroidal coil former's rotation axis over a greater length than the toroidal coil former itself. This creates a large stator that can absorb the main magnetic flux from the rotor, making it possible to use conventional rotor structures.

[0016] In particular, when designed as a radial flux machine, the lamellae extend in the direction of the rotation axis of the toroidal coil carrier over a length that is at least twice as long, in particular over a length that is at least three times as long, as the toroidal coil carrier.

[0017] The laminar structure is advantageously designed as a toroidal body. The laminations represent sections of the toroidal body. The sections for the individual coil bodies of the winding are arranged between these laminar sections.

[0018] In particular, the rotation axis of the toroidal coil carrier is identical to the rotation axis of the toroidal body of the lamellar structure.

[0019] Advantageously, the toroidal body has a cross-sectional area that is at least three times as large, in particular at least five times as large, as the cross-sectional area of ​​the toroidal coil carrier. As a result, the stator has a large air gap area to absorb the main magnetic flux from the rotor.

[0020] Advantageously, the maximum radial extent of the toroidal coil support is equal to the maximum radial extent of the toroidal body of the laminar structure, in each case starting from the rotational axis. In other words, the toroidal coil support and the laminar structure, which together constitute the stator, are flush with each other on their respective outer sides. This configuration is particularly provided for an internal rotor.

[0021] Alternatively, the minimum radial extension of the toroidal coil carrier can be equal to the minimum radial extension of the toroidal body of the laminar structure, in each case starting from the rotational axis. This configuration is particularly suitable for an external rotor.

[0022] Such a geometric design of the stator has the advantage that the coils wound from the winding wire partially protrude from the lamella structure and are therefore easily accessible for cooling.

[0023] In other words, the coils of the winding extend into a region that is radially farther from the rotational axis than the radially outermost region of the laminar structure. This configuration is particularly suitable for an internal rotor.

[0024] Alternatively, the winding may extend into a region which is radially less distant from the axis of rotation than the radially innermost region of the laminar structure.

[0025] In particular, the electric drive, in the design as a radial flux machine, comprises exactly one stator and exactly one rotor, and in the design as an axial flux machine, exactly two stators and exactly one rotor.

[0026] The toroidal coil carrier advantageously has a maximum circular ring diameter of a maximum of 200 mm, in particular a maximum of 100 mm, and / or at least 60 mm, in particular at least 80 mm. If the toroidal coil carrier has the cross-sectional shape of a circle, the diameter of the circle is in particular greater than 5 mm, in particular greater than 10 mm, and / or less than 20 mm, in particular less than 15 mm.

[0027] In particular, the stator surrounds the rotor, meaning the rotor is located in the core of the stator. This is a so-called inner rotor. Alternatively, the rotor surrounds the stator, which is a so-called outer rotor. The rotor is preferably a radial flux rotor.

[0028] If the cross-sectional area of ​​the toroidal coil carrier has the shape of an ellipse, the major axis of the ellipse is in particular a maximum of 1.3 times, in particular a maximum of 1.2 times, as long as the minor axis of the ellipse.

[0029] The stator consists of a 3D flux-conducting material with eddy current reduction measures. Examples include soft magnetic powder composites (SMC), ferrites, or nanocrystalline materials.

[0030] Short description of the drawings

[0031] Further embodiments, advantages, and applications of the invention will become apparent from the dependent claims and the following description with reference to the figures. These show:

[0032] Fig. la shows a first electric drive in a radial arrangement as an internal rotor;

[0033] Fig. 1b the stator of the first electric drive without the coils of the stator winding;

[0034] Fig. 1c the stator without the coils of the stator winding, viewed from above;

[0035] Fig. 1d shows a section through the stator without the coils of the stator winding according to the section line shown in Fig. 1c;

[0036] Fig. 1e shows the stator without the coils of the stator winding, viewed from the side; Fig. 1f shows a section through the stator along the line shown in Fig. 1e, where the hatched areas represent the coil bodies of the stator winding;

[0037] Fig. 2a a second electric drive in radial arrangement as an external rotor;

[0038] Fig. 2b the stator of the second electric drive without the coils of the stator winding;

[0039] Fig. 2c the stator without the coils of the stator winding, viewed from above;

[0040] Fig. 2d shows a section through the stator without the coils of the stator winding according to the section line shown in Fig. 2c;

[0041] Fig. 2e the stator without the coils of the stator winding viewed from the side;

[0042] Fig. 2f shows a section through the stator according to the section line shown in Fig. 2e, where the hatched areas represent the coil bodies of the stator winding;

[0043] Fig. 3a shows a third electric drive in axial arrangement;

[0044] Fig. 3b a stator part of the third electric drive;

[0045] Fig. 3c the stator part with a view of the flat surface;

[0046] Fig. 3d the stator part with view from the side; and

[0047] Fig. 4 shows the cross-sectional area of ​​a toroidal coil carrier in an alternative embodiment in the geometry of an ellipse.

[0048] Ways to implement the invention

[0049] Fig. 1a shows a first electric drive. This comprises a rotor 1 and a stator 2. Figs. 1b to 1f show only the stator 2, with the coils of winding 3 being shown as a hatched area in Fig. 1f.

[0050] The stator 2 comprises a toroidal coil carrier 21. The toroidal coil carrier 21 is a rotating body that rotates a cross-sectional area 211. In the present embodiment, the cross-sectional area 211 is a circle with an exemplary radius of 6 mm. A coil 3 is wound around the toroidal coil carrier 21. As mentioned, this is illustrated in Fig. 1f by the hatched area.

[0051] The toroidal coil carrier 21 refers only to that part of the stator 2 around which the coils of the winding are wound. In the present embodiment, this is a torus, which in Fig. 1f is bounded on the inside by the dashed line 212 and on the outside by the circular solid line 213.

[0052] The toroidal coil carrier 21 is supplemented by a laminar structure 22. The stator 2 thus comprises the toroidal coil carrier 21 and the laminar structure 22. The stator 2 is designed as a single piece, but can also consist of bonded sub-segments.

[0053] Between the laminations 221, sections 215 of the toroidal coil carrier 21 are freely arranged, around which coils 3 are wound. This means that the coils 3 do not surround the toroidal coil carrier 21 along the entire circular ring, but only in the sections 215 between the laminations 221. In the present embodiment, the stator 2 or the lamination structure 22 comprises a total of twelve laminations 221 and twelve sections 215 of the toroidal coil carrier 21 between the laminations 221.

[0054] In the direction of the rotation axis 214, the laminations 221 extend over a greater length LI, which is, for example, 40 mm, than the toroidal coil carrier 21 over a length L2. The length LI is approximately three times as long as the length L2. In the present embodiment, the lamination structure 22 is also a toroidal body. This is because the lamination structure 22 is a body of revolution in which the cross-sectional area 222 hatched in Fig. 1d is rotated about the rotation axis 214. The axes of rotation of the toroidal coil carrier 21 and the lamination structure 22 are identical. However, the lamination structure 22 is not continuous along the circular ring, but only present in sections. These sections of the lamination structure 22 are the laminations 221. The toroidal body of the lamellar structure 22 is interrupted between the laminations, so that spaces are formed for the coils of the winding 3.

[0055] The cross-sectional area 222 of the toroidal body of the lamella structure 22 is approximately six to seven times as large as the cross-sectional area 211 of the toroidal coil carrier 21. As a result, the stator 2 has a large air gap area to absorb the main magnetic flux from the rotor.

[0056] The maximum radial extension RI of the toroidal coil carrier 21 is exactly the same size as the maximum radial extension R2 of the laminar structure 22. This has the positive effect that the part 31 of the coils 3 stands freely outside the stator 2 and is easily accessible there for cooling 4. In other words, the coils of the winding 3 extend into a region which is radially further outward from the axis of rotation 214 than a radially outermost region of the laminar structure 22. The radii RI and R2 are 40 mm in this exemplary embodiment and correspond to the maximum annular diameter of the toroidal coil carrier 21 and the toroidal body of the laminar structure 22.

[0057] Fig. 2a shows a second electric drive. This also comprises exactly one rotor 1 and exactly one stator 2. Figs. 2b to 2f show only the stator 2, with the winding 3 shown in a hatched area in Fig. 2f. The reference numerals are used the same as in Figs. 1a to 1f. Since the rotor 1 surrounds the stator 2, it is a so-called "external rotor".

[0058] The stator 2 is constructed according to the same principles as the stator 2 of the first electric drive. It also comprises a toroidal coil carrier 21 with a circular cross-sectional area 211, around which the coils comprising the winding are arranged in sections.

[0059] One difference from the first electric drive is that the minimum radial extension R3 of the toroidal coil carrier 21 is exactly the same as the minimum radial extension R3 of the laminar structure 22. This has the positive effect that the part 31 of the winding 3 is free within the stator 2 and is easily accessible there for cooling 4. In other words, the winding 3 extends into a region which is radially further inward from the rotation axis 214 than a radially innermost region of the laminar structure 22.

[0060] Figs. 3a to 3d show an internal rotor in an axial arrangement. This comprises a rotor 1 and a stator 2 with two stator parts 2a and 2b. Both stator parts 2a and 2b are constructed according to the same principles as the stators of the first and second electric drives. One difference is that the toroidal coil carrier 21 is flush with the outermost side of the laminar structure 22 in the axial direction, rather than in the radial direction. The toroidal coil carrier 21 and the laminar structure 22 are flush at the dashed line 23.

[0061] Fig. 4 shows an ellipse 5. In a particular embodiment, the cross-sectional area 211 of the toroidal coil support 21 can have the shape of such an ellipse 5. For example, the ellipse has a major axis gA that is 1.2 times as long as the minor axis kA.

[0062] If the cross-sectional area of ​​the toroidal coil carrier has the shape of an ellipse, the major axis of the ellipse is in particular a maximum of 1.3 times, in particular a maximum of 1.2 times, as long as the minor axis of the ellipse.

[0063] While preferred embodiments of the invention are described in this application, it is to be clearly understood that the invention is not limited thereto and may be embodied in other ways within the scope of the following claims.

Claims

Patent claims 1. Electric drive comprising a stator (2) and a rotor (1) and a plurality of coils of a winding (3) , characterized in that the stator (2) has a toroidal coil carrier (21) with an axis of rotation (214) and the toroidal coil carrier (21) has the cross-sectional area (21) of an ellipse, in particular a circle, wherein the coils of the winding (3) are wound around sections (215) of the toroidal coil carrier (21).

2. Electric drive according to claim 1, wherein the stator (2) has a laminar structure (22) with a plurality of laminations (221), wherein the coils of the winding are each placed between the laminations (221) around the sections (215) of the toroidal coil carrier (21).

3. Electric drive according to claim 2, wherein the lamellae (221) extend in the direction of the axis of rotation (214) of the toroidal coil carrier (21) over a greater length than the toroidal coil carrier (21).

4. Electric drive according to claim 3, wherein the lamellae (221) extend in the direction of the axis of rotation (214) of the toroidal coil carrier (21) over a length at least twice as long, in particular at least three times as long, as the toroidal coil carrier (21).

5. Electric drive according to one of claims 2 to 4, wherein the lamellar structure (22) is designed as a toroidal body, and wherein the lamellar- len (221) sections of the toroidal body and between these sections there are spaces for the coils of the winding (3).

6. Electric drive according to claim 5, wherein the axis of rotation (214) of the toroidal coil carrier (21) is identical to the axis of rotation (214) of the toroidal body of the lamellar structure (22) .

7. Electric drive according to claim 5 or 6, wherein the toroidal body has a cross-sectional area (222) which is at least three times as large, in particular at least five times as large, as the cross-sectional area (211) of the toroidal coil carrier (21) .

8. Electric drive according to one of claims 5 to 7, wherein the maximum radial extent (RI) of the toroidal coil carrier (21) is equal to the maximum radial extent (R2) of the toroidal body of the lamellar structure (22), each originating from the axis of rotation (214), or wherein the minimum radial extent (R3) of the toroidal coil carrier (21) is equal to the minimum radial extent (R4) of the toroidal body of the lamellar structure (22), each originating from the axis of rotation (214).

9. Electric drive according to one of the preceding claims, wherein the winding extends into a region which is radially farther from the axis of rotation (214) than a radially outermost region of the lamella structure (22), or wherein the winding extends into a region which is radially less far from the axis of rotation (214) than the radially innermost region of the lamella structure (22).

10. Electric drive according to one of the preceding claims, comprising - exactly one stator (2) and exactly one rotor (1), or - exactly two stators and exactly one rotor.

11. Electric drive according to one of the preceding claims, wherein the toroidal coil carrier (21) has a maximum annular diameter and the maximum annular diameter is a maximum of 200 mm, in particular a maximum of 100 mm and / or a minimum of 60 mm, in particular a minimum of 80 mm.

12. Electric drive according to one of the preceding claims, wherein the stator (2) surrounds the rotor (1) or wherein the rotor (1) surrounds the stator (2).

13. Electric drive according to any of the preceding claims, wherein the rotor (1) is a radial flux rotor or an axial flux rotor.

14. Electric drive according to one of the preceding claims, wherein the elliptical shape of the cross-sectional area of ​​the toroidal coil carrier has a major axis and a minor axis, wherein the major axis is at most 1.3 times, in particular at most 1.2 times, as long as the minor axis.

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