Rotating electrical machine

Abstract

To provide an outer rotor type rotary electric machine capable of increasing magnetic flux density and performing high output by suppressing leakage of magnetic flux to an outer periphery of a rotor.SOLUTION: The present invention relates to an outer rotor type rotary electric machine consisting of a stator and a rotor disposed while interposing a predetermined gap in a radial direction with the stator. The rotor has a structure which consists of rotor cores, magnets and a housing and in which a plurality of magnets and the rotor cores are alternately disposed side by side in a circumferential direction. An outer peripheral side of the magnet has a long shape and is magnetized in the circumferential direction, and the rotor core and the magnet are in a mutually fitted structure. A stationary part size of the magnet in the housing is larger than a stationary part size of the rotor core in the housing, and the magnet includes a magnet expansion part closer to the rotor core in the circumferential direction and closer to the stator in the radial direction than a maximum width position of the rotor core with respect to a straight line connecting the maximum width position and a rotation center axis.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rotating electrical machine.

Background Art

[0002] In recent years, due to the increasing awareness of social sustainability and global warming, for example, in the aviation industry, efforts are being made to promote the electrification of aircraft in order to reduce carbon dioxide emissions. The internal combustion engines and fossil fuels used in aircraft have an output density that is an order of magnitude higher than that of conventional rotating electrical machines and batteries. Therefore, in order to replace the internal combustion engine with an electric component for electrification, a rotating electrical machine is required to achieve an output density of 10 to 15 kW / kg. To achieve the target output density, it is necessary to increase the magnetic flux density of the rotating electrical machine.

[0003] As a conventional method for increasing the magnetic flux density, there is a flux concentration type structure. As a flux concentration type structure, for example, there is one described in Patent Document 1. In Patent Document 1, by arranging magnets magnetized in the circumferential direction such that the same polarities face each other, the magnetic fluxes generated on the front and back sides of the magnets can be concentrated on the stator side, so that the output of the rotating electrical machine can be increased.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the rotating electrical machine described in Patent Document 1 mentioned above, since the magnets and the rotor core are arranged alternately in the circumferential direction, a part of the magnetic flux generated from the magnets arranged on the outer rotor leaks to the outer circumference of the rotor through the fixing part between the rotor core and the housing, resulting in a decrease in the output of the rotating electrical machine. Further, if the structure is such that the fixing part between the rotor core and the housing is made small to prevent this, there are problems that the fixing force of the rotor core decreases and stress concentration occurs near the interface between the rotor core and the magnet.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide an outer rotor type rotating electrical machine capable of preventing leakage of magnet magnetic flux to the outer circumference of the rotor, improving the fixing force of the rotor core, and alleviating stress concentration near the interface between the rotor core and the magnet, thereby increasing the magnetic flux density and achieving a higher output.

Means for Solving the Problems

[0007] Taking an example, the present invention is an outer rotor type rotating electrical machine composed of a stator and a rotor arranged with a predetermined gap in the radial direction with respect to the stator. The rotor is composed of a rotor core, magnets, and a housing, and has a structure in which a plurality of magnets and the rotor core are arranged alternately in the circumferential direction. The magnets are magnetized in the circumferential direction with a long outer peripheral side, and the rotor core and the magnets have a fitting structure. The size of the fixing part of the magnets in the housing is larger than the size of the fixing part of the rotor core in the housing, and the magnets have a magnet overhang part on the rotor core side in the circumferential direction and on the stator side in the radial direction with respect to the straight line connecting the maximum width position of the rotor core and the rotation center axis.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a rotating electrical machine capable of suppressing leakage magnetic flux from the fixing part between the rotor core and the housing, improving the fixing force of the rotor core, and alleviating stress concentration near the interface between the rotor core and the magnet.

Brief Description of the Drawings

[0009]

Figure 1

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Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment

[0011] FIG. 1 is a cross-sectional view of the rotating electrical machine 1 in this embodiment. In FIG. 1, the rotating electrical machine 1 is an outer-rotor type rotating electrical machine composed of a stator 2 and a rotor 3 arranged with a predetermined gap in the radial direction with respect to the stator 2. The stator 2 is configured by winding a stator winding 12 around the outer peripheries of a plurality of teeth 13 arranged on a stator core 11. The rotor 3 is composed of a rotor core (core) 21, magnets 22, and a housing 25, and has a structure in which a plurality of magnets 22 and the rotor core 21 are alternately arranged in the circumferential direction. The magnets 22 are magnetized with the outer peripheral side being a long shape in the direction of the circumferential magnetizing direction 23 and have a radial spoke shape. Also, the rotor core 21 and the magnets 22 have a fitting structure. Then, the magnets 22 and the rotor core 21 are fixed to the housing 25 with an adhesive, mechanical protrusions, or the like. Here, as shown in FIG. 1, the size of the magnet fixing portion 35 indicated by the dashed line, which is the fixing portion of the magnet 22 with respect to the housing 25, is larger than the size of the core fixing portion 36 indicated by the broken line, which is the fixing portion of the rotor core 21 with respect to the housing 25. As a result, the size of the core fixing portion 36, which is the fixing portion of the rotor core 21 and the housing 25, is reduced, so that the magnetic flux leaking to the outer periphery of the rotor is reduced, and the output of the rotating electrical machine 1 increases.

[0012] FIG. 2 shows a cross-sectional view of another example of the rotating electrical machine 1 in this embodiment. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and their descriptions are omitted. The difference from FIG. 1 in FIG. 2 is that the shapes of the rotor core 21 and the magnets 22 are changed so as to maximize the size of the magnet fixing portion 35 and minimize the size of the core fixing portion 36. Thereby, the leakage magnetic flux to the outer periphery of the rotor can be further reduced compared to FIG. 1.

[0013] Also, FIG. 3 shows a cross-sectional view of still another example of the rotating electrical machine 1 in the present embodiment. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and their descriptions are omitted. The difference from FIG. 1 in FIG. 3 is that a plurality of magnets 22 are in contact with each other and arranged in the circumferential direction, so that the core fixing portion 36 is eliminated, and the magnet fixing portion 35 is formed over the entire circumference of the housing 25. That is, the magnet 22 and the rotor core 21 are held in the housing 25 by the magnet fixing portion 35. Thereby, compared with FIGS. 1 and 2, the leakage magnetic flux to the outer periphery of the rotor can be further reduced.

[0014] In this way, by reducing the size of the core fixing portion 36, in other words, by arranging magnets with a long outer peripheral side closer to each other, the leakage magnetic flux can be reduced. However, as the core fixing portion 36 becomes smaller, the fixing force of the rotor core 21 decreases. Therefore, it is necessary to improve the fixing force of the rotor core 21. The solution will be described below.

[0015] FIG. 4 shows an enlarged view of the vicinity of the magnet 22 of the rotor 3 in the rotating electrical machine 1 of FIG. 2. In FIG. 4, the magnet 22 has a long outer peripheral side, and has a magnet overhang portion 24 on the rotor core 21 side in the circumferential direction and on the stator side in the radial direction with respect to a straight line 20 connecting the maximum width position of the rotor core 21 and the rotation center axis, rather than the maximum width position of the rotor core 21. Note that R is provided at the ends of the magnet 22 and the rotor core 21 to avoid stress concentration. Thereby, since the magnet overhang portion 24 mechanically holds the rotor core 21 from the inner peripheral side in the radial direction, the fixing force of the rotor core 21 against the electromagnetic attraction force acting on the stator 2 side is improved.

[0016] FIG. 5 is an enlarged view of the vicinity of a magnet for explaining a conventional rotating electrical machine. In FIG. 5, the same components as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 5, the conventional rotating electrical machine has a configuration without the magnet protruding portion 24 described in FIG. 4, and stress concentration occurs at a stress concentration portion 26 indicated by a broken line near the interface edge between the magnet 22 and the rotor core 21. On the other hand, in the present embodiment, as shown in FIG. 4, the magnet protruding portion 24 protrudes toward the rotor core 21 side in the circumferential direction, so that the stress concentration portion 26 indicated by the broken line is formed inside the rotor core 21 having a higher strength than the magnet 22 and the magnet adhesive for fixing it, and the stress concentration near the interface between the rotor core 21 and the magnet 22 can be alleviated. Further, after the rotor 3 is assembled, a magnetic field is applied to the magnet 22 through the rotor core 21, so that the magnet 22 can be magnetized in the circumferential direction, and the workability of assembling the rotor 3 is improved.

[0017] As described above, according to the present embodiment, by adopting a structure in which the size of the magnet fixing portion is larger than the size of the core fixing portion, in other words, by arranging magnets having a long outer peripheral side closer to each other, leakage magnetic flux from the fixing portion between the rotor core and the housing is suppressed. Further, the magnet protruding portion mechanically fixes the rotor core and alleviates stress concentration near the interface between the magnet and the rotor core, so that it is possible to provide an outer rotor type rotating electrical machine capable of increasing the magnetic flux density and achieving high output.

Embodiment

[0018] FIG. 6 is a cross-sectional view of the rotating electrical machine 1 in the present embodiment. FIG. 6 is a cross-sectional view of the rotating electrical machine 1 based on the configuration of FIG. 2 in Embodiment 1. Therefore, in FIG. 6, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. The difference between FIG. 6 and FIG. 2 is that an inner peripheral side rotor core 31 made of a soft magnetic material having a higher saturation magnetic flux density than the rotor core 21, for example, permendur or a grain-oriented electrical steel sheet, is formed on the inner peripheral side of the rotor core 21.

[0019] With such a configuration, the magnet protruding portion 24 narrows the width of the inner peripheral side rotor core 31, thereby preventing the magnetic flux of the inner peripheral side rotor core 31 from saturating and enabling the rotating electrical machine 1 to achieve high output.

Example

[0020] FIG. 7 is a cross-sectional view of the rotating electrical machine 1 in this embodiment. FIG. 7 is a cross-sectional view of the rotating electrical machine 1 based on the configuration of FIG. 2 in Embodiment 1. Therefore, in FIG. 7, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 7, the difference from FIG. 2 is that the rotor core 21 is divided in the circumferential direction, and an elastic body 32, for example, rubber, resin, etc. is disposed in a compressed manner between the divided rotor cores 21.

[0021] With such a configuration, the rotor core 21 is pressed against the surrounding magnets 22 by the elastic force of the elastic body 32. As a result, the gap due to the manufacturing tolerances of the magnets 22 and the rotor core 21 is reduced, the decrease in the output density of the rotating electrical machine 1 due to the increase in magnetic resistance caused by the gap is suppressed, and the fixing force of the rotor core 21 can be improved.

Example

[0022] FIG. 8 is a cross-sectional view of the rotating electrical machine 1 in this embodiment. FIG. 8 is a cross-sectional view of the rotating electrical machine 1 based on the configuration of FIG. 2 in Embodiment 1. Therefore, in FIG. 8, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 8, the difference from FIG. 2 is that the magnets 33 without overhang portions and the magnets 22 having overhang portions 24 are arranged alternately. The magnet 33 without an overhang portion is a sintered magnet having a high residual magnetic flux density but difficult to form into a complex shape, and the magnet 22 having the overhang portion 24 is formed of a bonded magnet having a low residual magnetic flux density but easy to form into a complex shape.

[0023] With such a configuration, a sintered magnet having a high residual magnetic flux density can be partially used, and the rotating electrical machine 1 can be made to have a higher output.

Example

[0024] FIG. 9 is an axial cross-sectional view of the rotating electrical machine 1 in this embodiment. In FIG. 9, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 9, the difference from FIG. 1 is that the core retaining rotor 5 and the leakage flux suppressing rotor 6 are arranged axially overlapping on the shaft 4. Although details will be described later, the rotor cores 21 of the core retaining rotor 5 and the leakage flux suppressing rotor 6 are integrated by a through-bar 34 in the axial direction.

[0025] FIG. 10 is a cross-sectional view of the core retaining rotor 5 in this embodiment. In FIG. 10, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 10, the difference from FIG. 1 is that the maximum width position of the rotor core 21 is located at the outermost periphery, and the rotor core 21 and the magnet 22 have a simple trapezoidal shape. Although magnetic flux leaks from the fixing portion between the housing 25 and the rotor core 21, the rotor core 21 can be held in a simple magnet shape that is easy to manufacture.

[0026] FIG. 11 is a cross-sectional view of the leakage flux suppressing rotor 6 in this embodiment. In FIG. 11, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 11, the difference from FIG. 2 is that the rotor core 21 has a triangular shape and the magnet 22 has a trapezoidal shape. Since there is no magnet overhang portion 24 in the magnet 22, the fixing force of the rotor core 21 is low, but the leakage of magnetic flux can be suppressed in a simple shape that is easy to manufacture.

[0027] The rotor cores 21 of the core retaining rotor 5 and the leakage flux suppressing rotor 6 have through-holes formed in the axial direction, and by passing a through-bar 34 formed of a non-magnetic material such as SUS304 or aluminum through the through-holes, the rotor cores 21 of the core retaining rotor 5 and the leakage flux suppressing rotor 6 are formed into an integral structure. Therefore, since the through-bar 34 supports the rotor core 21 of the leakage flux suppressing rotor 6, the fixing force of the rotor core 21 of the leakage flux suppressing rotor 6 is improved, and the stress at the stress concentration portion 26 is also relieved.

[0028] By adopting such a configuration, the shape of the magnet can be made into a simple shape that is easy to manufacture. Therefore, a sintered magnet with a high residual magnetic flux density can be used, the decrease in the output density of the rotating electrical machine 1 can be suppressed, and the fixing force of the rotor core 21 can be improved.

[0029] Although the above embodiments have been described, the present invention enables higher output by increasing the magnetic flux density of the rotating electrical machine, and can be applied to rotating electrical machines for aviation, vehicles, general industries, etc. that require higher output.

[0030] In addition, since the present invention can improve the output density of the rotating electrical machine, the power consumption of the rotating electrical machine can be reduced. Therefore, the carbon emission can be reduced, global warming can be prevented, and it contributes to Energy in particular item 7 for realizing the SDGs (Sustainable Development Goals).

[0031] Furthermore, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, for part of the configuration of each embodiment, addition, deletion, and replacement with other configurations are possible.

Explanation of Reference Numerals

[0032] 1: Rotating electrical machine, 2: Stator, 3: Rotor, 4: Shaft, 5: Core-retaining rotor, 6: Leakage flux suppressing rotor, 11: Stator core, 12: Stator winding, 13: Teeth, 21: Rotor core (core), 22: Magnet, 23: Magnet magnetization direction, 24: Magnet overhang portion, 25: Housing, 26: Stress concentration portion, 31: Inner peripheral side rotor core, 32: Elastic body, 33: Magnet without magnet overhang portion, 34: Through rod, 35: Magnet fixing portion, 36: Core fixing portion

Claims

1. An outer rotor type rotating electrical machine composed of a stator and a rotor disposed with a predetermined gap in the radial direction with respect to the stator, wherein the rotor is composed of a rotor core, magnets, and a housing, and has a structure in which a plurality of the magnets and the rotor core are alternately arranged in the circumferential direction, the magnets are magnetized in the circumferential direction with a long outer peripheral side, and the rotor core and the magnets have a fitting structure, a size of a fixing portion of the magnets in the housing is larger than a size of a fixing portion of the rotor core in the housing, the magnets have a magnet overhang portion on the rotor core side in the circumferential direction and on the stator side in the radial direction with respect to a straight line connecting a maximum width position of the rotor core and a rotation center axis, and is characterized by a rotating electrical machine.

2. In the rotating electrical machine according to Claim 1, the rotor core is divided in the radial direction, and an inner peripheral side of the rotor core is formed of a soft magnetic material having a higher saturation magnetic flux density than an outer peripheral side of the rotor core, and is characterized by a rotating electrical machine.

3. In the rotating electrical machine according to Claim 1, the rotor core is divided in the circumferential direction, and an elastic body is disposed between the divided rotor cores, and is characterized by a rotating electrical machine.

4. In the rotating electrical machine according to Claim 1, the rotor is formed by arranging magnets having the magnet overhang portion and magnets having no magnet overhang portion alternately in the circumferential direction, and is characterized by a rotating electrical machine.

5. In the rotating electrical machine according to Claim 1, a first rotor in which a maximum width position of the rotor core is located at the outermost circumference and a second rotor having a magnet having no magnet overhang portion are arranged axially overlapped, through holes are formed in respective rotor cores of the first rotor and the second rotor, and a non-magnetic material through rod is passed through the through holes to integrate the respective rotor cores, and is characterized by a rotating electrical machine.

6. In the rotating electrical machine according to Claim 1, there is no fixing portion of the rotor core in the housing, the magnets and the rotor core are held by a fixing portion of the magnets in the housing, and is characterized by a rotating electrical machine.

7. In the rotating electrical machine according to Claim 1, a plurality of the magnets have a structure in which they are in contact and arranged in the circumferential direction, the magnets and the rotor core are held by a fixing portion of the magnets in the housing, and is characterized by a rotating electrical machine.

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