WO2017043387A1

WO2017043387A1 - Magnetic gear device

Info

Publication number: WO2017043387A1
Application number: PCT/JP2016/075471
Authority: WO
Inventors: 山田　裕之; 顕杉浦
Original assignee: Ntn株式会社
Priority date: 2015-09-07
Filing date: 2016-08-31
Publication date: 2017-03-16

Abstract

Provided is a magnetic gear device capable of suppressing the loss of eddy current three-dimensionally flowing in a magnetic flux, and of providing high torque transmission efficiency. The magnetic gear device is provided with: first and second rotors (1, 2) each having a plurality of permanent magnets (1a, 2a); and a stator (3) that is disposed magnetically between the first rotor (1) and the second rotor (2) and that has a plurality of pole pieces (3a) capable of modulating a magnetic flux. The first rotor (1) is opposed to the stator (3) via a radial gap (RG) perpendicular to the rotation axis (O1) of the first rotor (1). The second rotor (2) is opposed to the stator (3) via an axial gap (AG) parallel to the rotation axis (O2) of the second rotor (2). The pole pieces 3a are formed of powder magnetic cores.

Description

Magnetic gear unit

Related applications

This application claims the priority of Japanese Patent Application No. 2015-175461 filed on September 7, 2015 and Japanese Patent Application No. 2015-225747 filed on November 18, 2015, which is incorporated herein by reference in its entirety. Quote as part.

The present invention relates to a magnetic gear device in which a driving rotor and a driven rotor transmit power without contact with each other.

Rotating electric motors such as motors are installed in driving units of automobiles, railways, industrial machines, and home appliances. The output of the rotary electric motor is converted into a desired torque or rotation speed by a gear and transmitted to the action portion. In a conventional general mechanical gear, a pair of gear teeth meshing with each other transmits power while being in contact with each other, so that friction occurs between the teeth. Therefore, there were the following problems.
(i) The teeth are worn and worn.
(ii) Vibration and noise are generated.
(iii) The teeth are damaged by the limit torque or fatigue failure.
(iv) Lubricants such as oil and grease are required and cannot be used in a clean environment.

All of the above problems will be solved if there is no contact between the teeth. There is a magnetic gear as a power transmission mechanism without contact between teeth. Since the magnetic gear is characterized in that it transmits power without contact, the absolute value of the transmittable torque is lower than that of a mechanical gear, but has the following many merits.
(i) There is almost no vibration or noise.
(ii) No dust generation. For this reason, it can be used in a clean environment.
(iii) There is almost no deterioration due to friction and wear, and maintenance-free can be realized.
(iv) Even if there is a partition between teeth, power transmission is possible if the partition is nonmagnetic. For this reason, it is possible for two teeth to exist in different media.
(v) It has a torque limiter function that steps out when torque exceeding the capacity is applied. If the mechanical gear receives more torque than it can, the teeth may be damaged.
(vi) Since there is no friction loss, high-efficiency torque transmission is possible depending on the configuration.

Patent Documents

1 and 2 describe a speed change mechanism using a magnetic gear.
In the magnetic gear device of Patent Document 1, the driving side and driven side rotors (external gears, internal gears) are arranged concentrically, and a stator (stator gear) is interposed between the rotors. Each rotor and the stator are opposed to each other via a radial gap. The stator is provided with a plurality of pole pieces (magnetic tooth portions) arranged in the circumferential direction. By using laminated electromagnetic steel sheets for this pole piece, eddy currents during rotation are reduced, and high-efficiency shifting is possible. Furthermore, the pole piece is skewed with respect to the axial direction, thereby reducing a steep change in the magnetic field and suppressing the cogging torque.

Also in the magnetic gear mechanism of Patent Document 2, a stator (a magnetic pole piece) that opposes the first and second rotors via a radial gap is interposed between the first and second rotors. . In Patent Document 2, a large torque can be transmitted by using a structure in which a permanent magnet of a rotor is embedded in a soft magnetic material. Furthermore, the permanent magnet is divided in the axial direction, so that eddy currents generated inside the rotating magnet are reduced and highly efficient torque transmission is possible.

Patent No. 5389122 Japanese Patent No. 5526281

As described above, in the speed change mechanism using the magnetic gears of

Patent Documents

1 and 2, both the rotor on the driving side and the driven side face the stator via the radial gap. With this configuration, the overall radial dimension is increased. On the other hand, in order to suppress the overall radial dimension, the first rotor of the driving and driven rotors faces the stator via a radial gap, and the second rotor is an axial gap. A magnetic gear device having a configuration facing the stator via a pin is conceivable.

If the first and second rotors are both opposed to the stator via the radial gap, or the first and second rotors are both opposed to the stator via the axial gap, the magnetic flux Since the flow has directionality, it is effective to use laminated electromagnetic steel sheets for the pole pieces. However, in the configuration in which the radial gap and the axial gap are combined, the flow of magnetic flux in the pole piece becomes three-dimensional. Therefore, even if laminated magnetic steel sheets are used for the pole piece, the vortex in one direction out of the radial direction and the axial direction Only the current component can be reduced, and the torque transmission efficiency is reduced.

The object of the present invention is to provide a three-dimensional structure in which the first rotor of the two rotors faces the stator via a radial gap and the second rotor faces the stator via an axial gap. It is an object of the present invention to provide a magnetic gear device that can suppress eddy current loss of a magnetic flux that flows and can realize high torque transmission efficiency.

A magnetic gear device according to one configuration of the present invention includes first and second rotors each having a plurality of permanent magnets, magnetically positioned between the first rotor and the second rotor, and a magnetic flux. And a stator having a plurality of pole pieces (magnetic pole pieces) for modulating the first rotor, the first rotor and the stator via a radial gap in a direction perpendicular to the rotation axis of the first rotor. The second rotor faces the stator through an axial gap in a direction parallel to the rotation axis of the second rotor, and the pole piece is formed of a dust core. .

According to this configuration, the rotation of the rotor on the driving side is transmitted to the rotor on the driven side at a gear ratio according to the number of pole pairs of the permanent magnets of both rotors. Since the first rotor faces the stator via the radial gap and the second rotor faces the stator via the axial gap, both the first and second rotors pass through the radial gap. Compared to the configuration facing the stator, the radial dimension of the entire magnetic gear device can be reduced. Further, the axial dimension of the entire magnetic gear device can be reduced as compared with the configuration in which the first and second rotors both face the stator via the axial gap.

In the case where the first rotor faces the stator via a radial gap and the second rotor faces the stator via an axial gap, the direction of magnetic flux flowing through the pole piece of the stator is three-dimensional. It becomes. For example, the direction of the magnetic flux acting between the magnetic poles of the first rotor and the second rotor is approximately the direction of the rotation axis of each rotor, but the magnetic pole boundary between the first rotor and the second rotor. In the part facing the vicinity, the magnetic flux is generated in the circumferential direction. For this reason, if the pole piece is composed of laminated electromagnetic steel sheets having only a two-dimensional magnetic flux direction suppressing effect, the effect of reducing eddy current loss is weak and torque transmission efficiency is reduced. However, if the pole piece is configured from the dust core as in this configuration, the effect of reducing eddy currents in the three-dimensional magnetic flux direction is high, so eddy current loss can be suppressed and torque transmission efficiency can be improved. it can.

In the second rotor, the plurality of permanent magnets are arranged on the same circumference so that directions of magnetic poles of two adjacent permanent magnets of the plurality of permanent magnets of the second rotor are different from each other. They may be arranged at an equal angle. In the second rotor, the plurality of permanent magnets may be arranged in a Halbach array. In either case, eddy current loss can be suppressed and torque transmission efficiency can be improved.

At least a portion of the pole piece that faces the first rotor may have a cross-sectional area that is perpendicular to the rotation axis of the first rotor as it approaches the second rotor. . The cross-sectional area may increase continuously as it approaches the second rotor, or may increase stepwise.

From the aspect of torque transmission performance between the first and second rotors, it is desirable that the mutual magnetic flux acts without waste between the first rotor and the second rotor. When the cross-sectional area of the pole piece increases as it approaches the second rotor, the flow of magnetic flux in the pole piece becomes smooth, and the leakage magnetic flux generated at a location far from the second rotor in the pole piece Can be minimized. As a result, the magnetic flux acting on the second rotor is increased, and the transmission torque and transmission efficiency are improved.

The portion other than the portion facing the first rotor in the pole piece has a smaller cross-sectional area perpendicular to the rotation axis of the first rotor as it approaches the second rotor. Also good.

In the case of a magnetic gear device in which the number of poles of the second rotor is large, the axial cross-sectional area of the portion other than the portion facing the first rotor of the pole piece increases as it approaches the second rotor. There is a possibility that the facing area of the pole piece with the second rotor becomes too large, and one pole piece is opposed across the N pole and N pole or the S pole and S pole adjacent in the circumferential direction. . Therefore, the axial cross-sectional area of the portion other than the portion facing the first rotor of the pole piece is reduced as it approaches the second rotor, so that the area of the pole piece facing the second rotor is reduced. This prevents the pole piece from straddling the adjacent N pole and N pole or S pole and S pole.

The shape of the surface of the pole piece facing the second rotor is two concentric arcs having different radii around the rotation axis of the second rotor, and the rotation of the second rotor. A fan-shaped shape surrounded by two straight lines extending radially from the shaft in different directions may be used.

When the shape of the surface of the pole piece facing the second rotor is substantially square, the same phenomenon as when the skew angle is provided in the motor occurs, and the effect of suppressing cogging torque and torque ripple can be expected. The maximum torque decreases. On the other hand, when the shape of the surface of the pole piece facing the second rotor is the above-mentioned fan shape, it is possible to suppress the decrease in the maximum torque.

The first rotor may be disposed radially inside the stator with respect to the rotation axis. Instead, the first rotor may be disposed radially outside the stator with the rotation axis as a reference. In either case, eddy current loss can be suppressed and torque transmission efficiency can be improved.

A magnetic field reinforcing back yoke made of a magnetic material may be provided on the back surface of the first and second rotors as viewed from the stator of one or both of the rotors. In this case, the magnetic field of the rotor provided with the back yoke is strengthened, and the transmittable torque increases.

The permanent magnet of the first rotor may be magnetized from the radial direction around the rotation axis of the first rotor. Instead, the permanent magnet of the first rotor may be magnetized from one direction along a plane perpendicular to the rotation axis of the first rotor. Further, the permanent magnets of the first rotor may be arranged in a Halbach array. In either case, eddy current loss can be suppressed and torque transmission efficiency can be improved.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the present invention.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.
1 is a perspective view of a magnetic gear device according to a first embodiment of the present invention. It is a figure which shows the flow of the magnetic flux of the pole piece in the magnetic gear apparatus of FIG. It is a perspective view of the magnetic gear apparatus concerning 2nd Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning 3rd Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning 4th Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning 5th Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning the 6th Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning the 7th Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning the 8th Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning the 9th Embodiment of this invention. FIG. 11 is a diagram showing a magnetic flux flow of a pole piece in the magnetic gear device of FIGS. 1 and 3 to 10. FIG. 11 is a diagram showing a first example of the shape (bottom surface) of the pole piece facing the second rotor in the magnetic gear device of FIGS. 1 and 3 to 10, and is a second example in which the bottom surface is hatched. It is a top view of the rotor of. FIG. 11 is a diagram illustrating a second example of the shape (bottom surface) of the pole piece facing the second rotor in the magnetic gear device of FIGS. 1 and 3 to 10, and is a second example in which the bottom surface is hatched. It is a top view of the rotor of. It is a perspective view of the magnetic gear apparatus concerning 10th Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning 11th Embodiment of this invention. It is a figure which shows the flow of the magnetic flux of the pole piece in the magnetic gear apparatus of FIG. It is a perspective view of the magnetic gear apparatus concerning the 12th Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning 13th Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning 14th Embodiment of this invention. It is a perspective view of the magnetic gear apparatus concerning 15th Embodiment of this invention. It is a top view of the 1st example of the 1st rotor. It is a top view of the 2nd example of the 1st rotor. It is a top view of the 3rd example of the 1st rotor.

Each embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a magnetic gear device MG according to the first embodiment. The magnetic gear device MG includes two rotors including first and

second rotors

1 and 2 and a stator 3 magnetically interposed between the first and

second rotors

1 and 2. Is provided. The first rotor 1 faces the stator 3 via a radial gap RG in a direction perpendicular to the rotation axis O1, that is, a radial direction, and the second rotor 2 is parallel to the rotation axis O2, that is, an axial direction. It faces the stator 3 through the axial gap AG. The rotation axes O1 and O2 of the first and

second rotors

1 and 2 are located on the same axis.

In the first rotor 1, a plurality of permanent magnets 1a are arranged on the circumference so as to form a cylinder around the rotation axis O1. Each permanent magnet 1a is magnetized in the radial direction, for example, as shown in FIG. Two adjacent permanent magnets 1a have opposite magnetic poles. That is, it is an NS arrangement in which N poles and S poles are alternately arranged. The first rotor 1 shown in FIG. 1 has two permanent magnets 1a.

In FIG. 1, the second rotor 2 has a plurality of permanent magnets 2a arranged on the circumference so as to form a cylinder around the rotation axis O2. Each permanent magnet 2a is magnetized in the direction of the rotation axis O2, for example. Two adjacent permanent magnets 2a have opposite magnetic poles. That is, it is an NS arrangement in which N poles and S poles are alternately arranged. The second rotor 2 shown in FIG. 1 has six permanent magnets 2a.

The stator 3 is composed of a plurality of pole pieces (magnetic pole pieces) 3a arranged at equal intervals on a circumference around the rotation axis O1 of the first rotor 1. Each pole piece 3a has an inner peripheral surface (a surface on the inner side in the radial direction with respect to the first rotor 1) of the first end portion (upper part in FIG. 1) as an outer peripheral surface of the first rotor 1. The second end face (end face) (the bottom face in FIG. 1) faces the one end face of the second rotor 2.

In this embodiment, the pole piece 3a has an L shape. In other words, the inner peripheral surface that is the surface facing the first rotor 1 is the same cylindrical surface over the entire axial direction, and the outer periphery that is the surface on the back side when viewed from the first rotor 1. The surface (the surface on the outer side in the radial direction with respect to the first rotor 1) is such that the diameter of a part of the second rotor 2 (the lower end in FIG. 1) is larger than the diameter of the other part. Is stepped. The width of the pole piece 3a in the circumferential direction is the same over the entire axial direction. As will be described later, the shape of the pole piece 3a may be other than the above.

The number of pole pieces 3 a is the sum of the number of pole pairs of the first and

second rotors

1 and 2. In this example, the first rotor 1 is a 2-pole or 1-pole pair, and the second rotor 2 is a 6-pole or 3-pole pair, so 1 (number of pole pairs) +3 (number of pole pairs) = 4 (The number of pole pieces), and the stator 3 has four pole pieces 3a. Even if the number of pole pairs of the first and

second rotors

1 and 2 is different from the number of pole pairs of the

rotors

1 and 2 of this embodiment, the number of pole pairs and poles of the first and

second rotors

1 and 2 The above relationship with the number of pieces 3a can be established.

As described above, the stator 3 faces the first rotor 1 via the radial gap RG, and faces the second rotor 2 via the axial gap AG, so that the stator 3 becomes the rotor. 1 and 2 are magnetically coupled. As a result, the rotation of the rotor on the driving side is transmitted to the rotor on the driven side at a gear ratio according to the number of pole pairs of both rotors. The rotation direction of the rotor on the driven side is opposite to the rotation direction of the rotor on the driving side. For example, if the second rotor 2 is a rotor on the driving side, and the first rotor 1 is a rotor on the driven side, the first rotor 1 with respect to the rotation of the second rotor 2. Rotates in the reverse direction at 3 times the speed. In this case, the magnetic gear device MG serves as a speed increaser. When the driving side and the driven side are switched, the magnetic gear device MG becomes a reduction gear.

The pole piece 3a is composed of a dust core. The dust core is an iron core obtained by making a magnetic material into a fine powder, covering the surface of the powder with an insulating coating and hardening it, and is also called a dust core. Since the dust core has a structure insulated at the powder level, the effect of reducing eddy currents in all magnetic flux directions is high.

The reason why the pole piece 3a is composed of a dust core will be described.
When the first rotor 1 is opposed to the stator 3 via the radial gap RG and the second rotor 2 is opposed to the stator 3 via the axial gap AG, each pole piece of the stator 3 The direction of magnetic flux flowing through 3a is three-dimensional. As shown in FIG. 2, the direction of the magnetic flux acting between the magnetic poles of the first rotor 1 and the second rotor 2 is approximately the direction of the rotation axes O1 and O2 of the

rotors

1 and 2, Magnetic flux is generated in the circumferential direction at a portion facing the vicinity of the magnetic pole boundary of the first rotor 1 and the second rotor 2. For this reason, when the pole piece 3a is formed of a laminated electromagnetic steel sheet having only a two-dimensional magnetic flux direction suppressing effect, the effect of reducing eddy current loss is weak and torque transmission efficiency is reduced. However, if the pole piece is formed from the dust core, the effect of reducing eddy currents in the three-dimensional magnetic flux direction is high, so that eddy current loss can be suppressed and torque transmission efficiency can be improved.

In this magnetic gear device, since the first and

second rotors

1 and 2 transmit torque without contact with each other, the merit of the magnetic gear device is applicable as it is. Further, a partition wall can be inserted in both or one of the radial gap RG portion between the first rotor 1 and the stator 3 and the axial gap AG portion between the second rotor 2 and the stator 3. Therefore, the first and

second rotors

1 and 2 can be driven in different media. Therefore, this magnetic gear device is suitable for applications such as a pump.

FIG. 3 shows a magnetic gear device MG according to the second embodiment. In the magnetic gear device according to the first embodiment of FIG. 1, the first rotor 1 is disposed on the inner peripheral side of the stator 3, whereas the magnetic gear device MG of FIG. The rotor 1 is arranged on the outer side in the radial direction of the stator 3 with the rotation axis O1 as a reference. Other configurations are the same as those of the magnetic gear device of FIG. Even if the first rotor 1 is arranged on the inner side in the radial direction of the stator 3 and on the outer side in the radial direction with respect to the rotation axis O1, the effect of reducing the three-dimensional eddy current is similarly obtained. can get.

In both the magnetic gear device of FIG. 1 and the magnetic gear device of FIG. 3, the magnitude relationship between the first rotor 1 and the second rotor 2 can be arbitrarily determined. For example, even if the first rotor 1 is arranged on the inner peripheral side of the stator 3 as in the magnetic gear device of FIG. 1, the shape of the pole piece 3a of the stator 3 is devised. Thus, the diameter of the first rotor 1 may be larger than the diameter of the second rotor 2. Further, even if the first rotor 1 is arranged on the outer side in the radial direction of the stator 3 with respect to the rotation axis O1 as in the magnetic gear device of FIG. 3, the first rotor 1 May be smaller than the diameter of the second rotor 2.

FIG. 4 shows a magnetic gear device MG according to the third embodiment. This magnetic gear device MG is obtained by adding first and second back yokes 4 and 5 for magnetic field enhancement to the magnetic gear device of FIG. Each of the

back yokes

4 and 5 is made of a magnetic material. The first back yoke 4 is provided on the inner peripheral surface of the first rotor 1, and the second back yoke 5 is provided on the bottom surface of the second rotor 2. The inner peripheral surface of the first rotor 1 and the bottom surface of the second rotor 2 are surfaces on the back side when viewed from the stator 3 in the first and

second rotors

1 and 2, respectively. When the first and second back yokes 4 and 5 are provided, the magnetic fields of the first and

second rotors

1 and 2 are strengthened, and the transmittable torque is increased.

FIG. 5 shows a magnetic gear device MG according to the fourth embodiment. This magnetic gear device MG is obtained by adding first and second back yokes 4 and 5 for magnetic field reinforcement to the magnetic gear device of FIG. The first back yoke 4 is provided on the outer peripheral surface of the first rotor 1, and the second back yoke 5 is provided on the bottom surface of the second rotor 2. In the fourth embodiment, similarly to the third embodiment, the magnetic fields of the first and

second rotors

1 and 2 are strengthened, and the transmittable torque is increased.

4 and 5, the

back yokes

4 and 5 are provided on both the first and

second rotors

1 and 2, but the back yoke 4 (only on one rotor 1 (2) is provided. 5) may be provided.

FIG. 6 shows a magnetic gear device MG according to the fifth embodiment. The magnetic gear device MG is different from the magnetic gear device of FIG. 1 in that the arrangement of the permanent magnets of the second rotor 2 is not the NS arrangement of the magnetic gear apparatus but the Halbach arrangement. That is, axially magnetized permanent magnets 2b magnetized in the direction of the rotation axis O2 and circumferentially magnetized permanent magnets 2c magnetized in the circumferential direction are alternately arranged on the same circumference. The magnetization directions of two adjacent axially magnetized permanent magnets 2b are opposite to each other, and the magnetization directions of two adjacent circumferentially magnetized permanent magnets 2c are opposite to each other. Other configurations are the same as those of the magnetic gear device of FIG.

Thus, by making the arrangement of the

permanent magnets

2b, 2c of the second rotor 2 a Halbach arrangement, the magnetic field of the second rotor 2 is strengthened, and the transmittable torque of the magnetic gear device is increased. Drive transmission is possible even when the axial gap AG is widened.

7 to 9 show magnetic gear devices MG according to the sixth to eighth embodiments, respectively. These magnetic gear devices MG are different from the magnetic gear devices shown in FIGS. 3, 4 and 5 in that the arrangement of the permanent magnets of the second rotor 2 is not an NS arrangement but a Halbach arrangement. There is a point. Other configurations are the same as those of the magnetic gear devices of FIGS. 3, 4, and 5. Also in this case, the same operation and effect as described above can be obtained.

Hereinafter, embodiments in which the shape of the pole piece 3a is different from the magnetic gear device according to the first to eighth embodiments will be described.
FIG. 10 shows a magnetic gear device MG according to the ninth embodiment. Each pole piece 3a of the magnetic gear device MG has a taper in which the outer peripheral surface, which is the back surface as viewed from the first rotor 1, continuously increases in diameter from the upper end to the vicinity of the lower end in FIG. It is formed into a shape. The inner peripheral surface of the pole piece 3a is provided with a step 12 at the boundary between the first portion 10 facing the first rotor 1 and the second portion 11 which is the other portion. The inner peripheral diameter of the second portion 11 is larger than the inner peripheral diameter of the first portion 10 facing the child 1. As for the shape of the pole piece 3a, at least for the first portion 10, the axial cross-sectional area, that is, the cross-sectional area of the cross section perpendicular to the rotation axis O1 is continuously increased as the second rotor 2 is approached. . Further, the axial cross-sectional area of the second portion 11 is continuously increased as the second portion 11 approaches the second rotor 2.

When the pole piece 3a has the above shape, as shown in FIG. 11, the flow of magnetic flux in the pole piece 3a becomes smooth, and the leakage magnetic flux generated at a location far away from the second rotor 2 in the pole piece 3a. Φ can be minimized. This was confirmed by testing. By suppressing the leakage magnetic flux, the magnetic flux acting on the second rotor 2 is increased, and the transmission torque and the transmission efficiency are improved.

The pole piece 3a has a continuously increasing diameter on the outer peripheral surface from the upper end of the figure to the vicinity of the lower end of the figure, but it may be increased stepwise. Also in that case, there is an effect of suppressing the leakage magnetic flux generated in the part far away from the second rotor 2 in the pole piece 3a.

As shown in FIG. 12, the magnetic gear device of the first to ninth embodiments described so far has a bottom surface 13 (a hatched portion) which is a surface facing the second rotor 2 in the pole piece 3a. ) May be substantially rectangular. Thus, when the shape of the bottom surface 13 of the pole piece 3a is substantially square, the same phenomenon as when the skew angle is provided in the motor occurs, and the effect of suppressing the cogging torque and torque ripple can be expected. Will decline.

As a countermeasure, in the magnetic gear device according to the first to ninth embodiments, the shape of the bottom surface 13 of the pole piece 3a may be a fan shape shown in FIG. The fan-shaped shape is such that two

concentric arcs

14 and 15 having different radii around the rotation axis O2 of the second rotor 2 and radial directions from the rotation axis O2 of the second rotor 2 in different directions. The shape is surrounded by two extending

radial lines

16 and 16. In this example, the radii of the two

concentric arcs

14 and 15 coincide with the outer diameter and the inner diameter of the second rotor 2, respectively. Thus, the fall of the maximum torque can be suppressed by making the shape of the bottom face 13 of the pole piece 3a into a fan-shaped shape. The optimum angle of the central angle θ formed by the two radial

straight lines

16 and 16 depends on the number of poles of the second rotor 2 and the axial gap AG (FIG. 10) between the second rotor 2 and the pole piece 3a. Dependent. The optimum angle of the center angle θ is obtained by magnetic field analysis or the like.

The magnetic gear device MG of FIG. 10 not only has the axial cross-sectional area of the first portion 10 of the pole piece 3a continuously increased as it approaches the second rotor 2, The axial cross-sectional area of the portion 11 also increases continuously as it approaches the second rotor 2. This is to make the flow of magnetic flux in the pole piece 3a smooth. However, depending on the number of pole pairs of the first rotor 1 and the second rotor 2, the second portion 11 has the above shape. You may not be able to. The second portion 11 corresponds to “a portion other than the portion directly facing the first rotor”.

For example, in the magnetic gear device according to the tenth embodiment shown in FIG. 14, the number of poles of the second rotor 2 is larger than that of the magnetic gear device according to the first to ninth embodiments. In this magnetic gear device, when the axial cross-sectional area of the second portion 11 of the pole piece 3a increases as it approaches the second rotor 2, the area of the pole piece 3a facing the second rotor 2 is increased. Is too large, and there is a possibility that one pole piece 3a is opposed across the N pole and N pole or the S pole and S pole adjacent in the circumferential direction. Therefore, by reducing the axial cross-sectional area of the second portion 11 of the pole piece 3a as it approaches the second rotor 2, the area of the pole piece 3a facing the second rotor 2 is reduced, The pole piece 3a is prevented from straddling adjacent N poles and N poles or S poles and S poles.

In the magnetic gear device MG according to the tenth embodiment shown in FIG. 14, the first rotor 1 has two poles (one pole pair), the second rotor 2 has twelve poles (six pole pairs), and a pole piece. In this example, 3a is 7 pieces (one pole pair + six pole pairs). Generally, as the number of poles of the second rotor 2 increases, the area of the pole piece 3a facing the second rotor 2 needs to be reduced. In the magnetic gear device of FIG. 14, the axial cross-sectional area of the pole piece 3 a is reduced in a tapered shape as it approaches the second rotor 2, but may be reduced stepwise.

FIG. 15 shows a magnetic gear device MG according to the eleventh embodiment. The pole piece 3a of this magnetic gear device MG has the same outer diameter from the upper end of the figure to the lower end of the figure. The inner peripheral surface of the pole piece 3a has a stepped portion 12 at the boundary between the first portion 10 and the second portion 11 as in the embodiment shown in FIG. The vertical cross-sectional shape of the pole piece 3a is almost a rectangle.

When the cross-section along the radial direction of the pole piece 3a is a shape close to a rectangle, as shown in FIG. Therefore, the cross-sectional shape along the radial direction of the pole piece 3a close to the rectangle is not so preferable from the viewpoint of torque transmission efficiency. However, since the shape is simple, there is an advantage that it is easy to mold and can be easily fixed and positioned with respect to the housing in which the magnetic gear device is accommodated.

FIG. 17 shows a magnetic gear device MG according to the twelfth embodiment. The pole piece 3a of the magnetic gear device MG has both the outer peripheral surface and the inner peripheral surface having the same diameter from the upper end of the drawing to the lower end of the drawing, and the cross section along the radial direction is completely rectangular. The complete rectangular shape is simpler and easier to form than the cross-sectional shape along the radial direction, which is close to the rectangle in FIG. The torque transmission efficiency is substantially the same as that of the magnetic gear device of FIG.

The L-shaped pole piece 3a shown in FIG. 1 has a shape in which the outer diameter of the lower end portion in the drawing is stepwise larger than the outer diameter of the portion other than the lower end portion. It is a kind of form in which the directional cross-sectional area increases in steps. However, if the pole piece 3a is limited to the portion facing the first rotor 1, the axial cross-sectional area does not increase as the second rotor 2 is approached.

The magnetic gear device of FIG. 1 provided with the L-shaped pole piece 3a having the above-described configuration is the same as the magnetic gear device provided with the pole piece 3a having the tapered outer peripheral surface shown in FIG. 10 and the rectangular shape shown in FIGS. Or it has an intermediate characteristic with the magnetic gear apparatus provided with the pole piece 3a of the cross-sectional shape along the radial direction close | similar to a rectangle. That is, the torque transmission efficiency is superior to the magnetic gear device of FIG. 15 or FIG. 17, but is inferior to the magnetic gear device of FIG. On the other hand, the ease of molding is superior to the magnetic gear device of FIG. 10, but inferior to the magnetic gear device of FIG. 15 or FIG. The shape of the pole piece 3a to be used may be determined according to the purpose and application of the magnetic gear device.

FIG. 18 shows a magnetic gear device MG according to the thirteenth embodiment. The pole piece 3a of the magnetic gear device MG is cut out in a substantially triangular pyramid shape from the outer peripheral surface to the side surface facing the circumferential direction in the upper portion of the figure, so that the axial sectional area becomes closer to the second rotor 2. The form gradually increases. By forming the pole piece 3a in this way, it is possible to suppress the leakage magnetic flux generated at a position far away from the second rotor 2 in the pole piece 3a, and to improve the transmission torque and the transmission efficiency. . Although not shown, combining the technique of notching in a substantially triangular pyramid and the technique of forming the outer peripheral surface in a tapered shape has an effect of improving the transmission torque and transmission efficiency.

FIG. 19 shows a magnetic gear device MG according to a fourteenth embodiment. This magnetic gear device MG is a pole piece that suppresses leakage of magnetic flux with respect to a magnetic gear device in which the first rotor 1 is arranged radially outside the stator 3 with respect to the rotation axis O1. The shape of 3a is applied. The pole piece 3a of this magnetic gear device has a taper whose diameter continuously increases from the upper end of the drawing toward the vicinity of the lower end of the drawing from the inner peripheral surface, which is the surface on the back side when viewed from the first rotor 1. It is formed into a shape. As for the outer peripheral surface of the pole piece 3a, the diameter of the lower end part of a figure is larger stepwise than the diameter of another part.

The shape of the pole piece 3a also increases in the axial cross-sectional area as it approaches the second rotor 2, similarly to the magnetic gear device of FIG. For this reason, the leakage magnetic flux which generate | occur | produces in the site | part far away from the 2nd rotor 2 in the pole piece 3a can be suppressed to the minimum, and transmission torque and transmission efficiency improve.

FIG. 20 shows a magnetic gear device MG according to the fifteenth embodiment. This magnetic gear device MG is obtained by adding first and second back yokes 4 and 5 for magnetic field enhancement to the magnetic gear device of FIG. The first back yoke 4 is provided on the inner peripheral surface of the first rotor 1, and the second back yoke 5 is provided on the bottom surface of the second rotor 2. By adding the first and second back yokes 4 and 5 to the magnetic gear device having the pole piece 3a having such a shape that can suppress the leakage magnetic flux, the first and

second rotors

1 and 2 are added. The magnetic field is further strengthened and the transmittable torque is increased.

21 to 23 are views of different first rotors as viewed from the axial direction. The first rotor 1 shown in FIG. 21 has an NS arrangement in which N poles and S poles are alternately arranged on the circumference, and is radial magnetization in which the permanent magnet 1a is magnetized from the radial direction. The rotor 1 shown in FIG. 22 has an NS arrangement, but is a parallel magnetization in which the permanent magnet 1a is magnetized from one direction on a plane perpendicular to the rotation axis O1. Further, in the first rotor 1 shown in FIG. 23, a permanent magnet 1b magnetized in the radial direction and a permanent magnet 1c magnetized in the circumferential direction are arranged in a Halbach array.

The magnetic gear device of each of the above embodiments shows an example in which the first rotor 1 is an NS array (FIG. 21 or FIG. 22), but the first rotor 1 is a Halbach array (FIG. 23). It is also good. In this case, the magnetic field of the first rotor 1 is strengthened, the transmittable torque of the magnetic gear device is increased, and drive transmission is possible even if the radial gap RG is widened.

As mentioned above, although the form for implementing this invention based on the Example was demonstrated, embodiment disclosed here is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1

1st rotor

1a, 1b, 1c Permanent magnet 2

2nd rotor

2a, 2b, 2c Permanent magnet 3 Stator 3a Pole piece AG Axial gap O1 Rotation axis O2 of 1st rotor 2nd rotor Axis of rotation RG radial gap

Claims

First and second rotors each having a plurality of permanent magnets;
A stator magnetically positioned between the first rotor and the second rotor and having a plurality of pole pieces for modulating magnetic flux;
The first rotor faces the stator through a radial gap in a direction perpendicular to the rotation axis of the first rotor, and the second rotor is the second rotor. Facing the stator through an axial gap in a direction parallel to the rotation axis,
A magnetic gear device in which the pole piece is composed of a dust core.
2. The magnetic gear device according to claim 1, wherein the second rotor is configured such that the directions of the magnetic poles of two adjacent permanent magnets of the plurality of permanent magnets of the second rotor are different from each other. A magnetic gear device in which the plurality of permanent magnets are arranged at an equal angle on the same circumference.
2. The magnetic gear device according to claim 1, wherein the second rotor includes the plurality of permanent magnets arranged in a Halbach array.
4. The magnetic gear device according to claim 1, wherein at least a portion of the pole piece that is directly opposed to the first rotor approaches the first rotor as the first rotor approaches. The magnetic gear device in which the cross-sectional area of the cross section perpendicular to the rotation axis of the rotor is large.
5. The magnetic gear device according to claim 4, wherein at least a portion of the pole piece that is opposed to the first rotor is perpendicular to a rotation axis of the first rotor as the second rotor is approached. A magnetic gear device having a continuously increasing cross-sectional area.
6. The magnetic gear device according to claim 4, wherein a portion of the pole piece other than a portion facing the first rotor is closer to the second rotor as the first rotor is reached. The magnetic gear device in which the cross-sectional area of the cross section perpendicular to the rotation axis is small.
The magnetic gear device according to any one of claims 1 to 6, wherein a shape of a surface of the pole piece facing the second rotor is centered on a rotation axis of the second rotor. A magnetic gear device having a fan-like shape surrounded by two concentric arcs having different radii and two straight lines extending radially from the rotation axis of the second rotor in different directions.
The magnetic gear device according to any one of claims 1 to 7, wherein the first rotor is disposed radially inward of the stator with reference to a rotation axis thereof.
The magnetic gear device according to any one of claims 1 to 7, wherein the first rotor is disposed radially outside the stator with respect to a rotation axis thereof.
10. The magnetic gear device according to claim 1, wherein one or both of the first and second rotors has a magnetic surface on a back surface as viewed from the stator. 10. A magnetic gear device provided with a magnetic field reinforcing back yoke made of a material.
11. The magnetic gear device according to claim 1, wherein the permanent magnet of the first rotor is magnetized from a radial direction around a rotation axis of the first rotor. Magnetic gear unit.
The magnetic gear device according to any one of claims 1 to 10, wherein the permanent magnet of the first rotor is from one direction along a plane perpendicular to the rotation axis of the first rotor. Magnetic gear unit that is magnetized.
The magnetic gear device according to any one of claims 1 to 10, wherein the permanent magnets of the first rotor are arranged in a Halbach array.