Axial gap induction motor

Abstract

To provide an axial gap induction motor that can achieve higher efficiency than conventional models. [Solution] An axial gap induction motor 100 comprising a first stator 110, a second stator 120, and a rotor 130, wherein an axial magnetic flux passing through the rotor 130 can be formed between a first coil 113 and a second coil 123, and the rotor 130 has a first radially inner annular portion 131, a second radially outer annular portion 132, and a plurality of connecting portions 133 that radially connect the first annular portion 131 and the second annular portion 132, all made of a non-magnetic conductor, and a magnetic portion 134 is provided in the region surrounded by the first annular portion 131, the second annular portion 132 and the connecting portions 133.

Description

Technical Field

[0006]

[0001] This invention relates to an induction motor, and particularly to an axial-gap type induction motor.

Background Art

[0002] There is an induction motor that generates an induced current in the rotor of an electric conductor by the rotating magnetic field created by the stator and generates a rotational torque corresponding to the slip. This induction motor is characterized by not requiring a permanent magnet. As an induction motor, a radial-gap type induction motor having a stator on the outer peripheral side and a rotor on the inner periphery of the stator, for example, a squirrel-cage induction motor, is generally well known. On the other hand, in order to miniaturize the induction motor, an axial-gap induction motor in which the stator and the rotor are arranged overlappingly in the axial direction of the rotating shaft has also been proposed. This type of axial-gap induction motor is proposed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although various proposals have been made for axial-gap induction motors, they are characterized by being difficult to improve efficiency due to the relationship between the stator and the rotor arranged in the axial direction. Therefore, the realization of an axial-gap induction motor capable of achieving higher efficiency than conventional ones has been desired.

[0005] An object of the present invention is to provide an axial-gap induction motor capable of achieving higher efficiency than conventional ones.

Means for Solving the Problems

[0006] The axial gap induction motor according to this invention comprises a planar first stator having a first coil, a planar second stator having a second coil and positioned opposite the first stator, and a planar rotor rotatably positioned between the first stator and the second stator, and an axial magnetic flux passing through the rotor can be formed between the first coil and the second coil. The rotor has a radially inner first annular portion, a radially outer second annular portion, and a plurality of connecting portions radially connecting the first annular portion and the second annular portion, all made of a non-magnetic conductor, and a magnetic portion is provided in the region surrounded by the first annular portion, the second annular portion and the connecting portions.

[0007] In the axial gap induction motor according to this invention, the first stator comprises a planar first core and a first coil provided on the rotor side along the first core, and the second stator comprises a planar second core and a second coil provided on the rotor side along the second core.

[0008] In the axial gap induction motor according to this invention, the first coil and the second coil are wound using a distributed winding method.

[0009] In the axial gap induction motor according to this invention, the first stator and the second stator are formed in a shape that lacks a part of the ring, and the rotor has a region that is not covered by the first stator and the second stator.

[0010] In the axial gap induction motor according to this invention, when M is the number of poles of the rotating magnetic field formed in the first coil and the second coil, and N is the number of connecting parts, the condition 100M ≥ N ≥ 3M is satisfied. [Effects of the Invention]

[0011] According to this invention, an axial gap induction motor is provided, comprising a planar first stator having a first coil, a planar second stator arranged opposite the first stator and having a second coil, and a planar rotor rotatably arranged between the first and second stators. The rotor is provided with a plurality of annular portions, connecting portions connecting the plurality of annular portions, and magnetic portions in the region surrounded by the plurality of annular portions and the connecting portions. This allows for the formation of an axial magnetic flux passing through the rotor between the first and second coils, thereby providing an axial gap induction motor that can be made more efficient than conventional ones. [Brief explanation of the drawing]

[0012] [Figure 1] This is an exploded perspective view showing the axial gap induction motor in Embodiment 1 in a disassembled state. [Figure 2] This is a configuration diagram showing the rotor configuration included in the axial gap induction motor in Embodiment 1. [Figure 3] This is a perspective view showing an axial gap induction motor in Embodiment 1. [Figure 4] This is an explanatory diagram showing the magnetic characteristics of the axial gap induction motor in Embodiment 1. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the axial gap induction motor of the present invention will be described with reference to the drawings. In each figure, the same parts are denoted by the same reference numerals.

[0014] Embodiment 1. First, the basic overall configuration of the axial gap induction motor 100 in Embodiment 1 will be described with reference to Figures 1 to 3. Figure 1 is an exploded perspective view showing the axial gap induction motor 100 in its disassembled state according to Embodiment 1. Figure 2 is a configuration diagram showing the configuration of the rotor 130 included in the axial gap induction motor 100 according to Embodiment 1. Figure 3 is a perspective view showing the axial gap induction motor 100 according to Embodiment 1.

[0015] [Configuration of the axial gap induction motor 100] The axial gap induction motor 100 of Embodiment 1 mainly comprises a first stator 110, a second stator 120, and a rotor 130, stacked in the axial direction. Here, the axial direction is defined as the direction along the axis of rotation of the rotation shaft (not shown) provided at the rotation center of the rotor 130.

[0016] The first stator 110 and the second stator 120 are arranged facing each other, with a space in between for the rotor 130. The first stator 110 is provided with a first case 111, a first core 112, a first coil 113, and a first coil cover 114. The second stator 120 is provided with a second case 121, a second core 122, a second coil 123, and a second coil cover 124. The first stator 110 and the second stator 120 are configured in a planar shape and may be formed in an annular shape or in a shape with a part of the annulus missing.

[0017] The first case 111 comprises a first flat section 111a, a first outer cylinder section 111b, and a first inner cylinder section 111c. The second case 121 comprises a second flat section 121a, a second outer cylinder section 121b, and a second inner cylinder section 121c. The first case 111 and the second case 121 are connected by the first outer cylinder section 111b and the second outer cylinder section 121b to form the housing of the axial gap induction motor 100. The first inner cylinder section 111c and the second inner cylinder section 121c are not in contact with each other, and a space is provided for the rotor 130.

[0018] The first core 112 is configured in a planar shape within the area surrounded by the first case 111. The first core 112 is not provided with slots used for concentrated winding coils or the like. The second core 122 is configured in a planar shape within the area surrounded by the second case 121. The second core 122 is not provided with slots used for concentrated winding coils or the like.

[0019] The first coil 113 is provided along the first core 112 on the side of the rotor 130 of the first core 112. The first coil 113 is wound by distributed winding. The second coil 123 is provided along the second core 122 on the side of the rotor 130 of the second core 122. The second coil 123 is wound by distributed winding. Here, distributed winding is a winding method in which, unlike concentrated winding where winding is concentrated for each slot, the coil is distributed over the entire range where the coil is provided. Since the first coil 113 and the second coil 123 are configured by distributed winding, it becomes possible to make the axial-gap induction motor 100 thinner than in the case of concentrated winding for each slot. And by making the first coil 113 and the second coil 123 into distributed windings, the distance between the first core 112 and the first coil 113 and between the second core 122 and the second coil 123 becomes shorter, and it becomes possible to form a stronger magnetic flux than before even with the same drive current. The first coil 113 and the second coil 123 can generate a rotating magnetic field by an axial magnetic flux passing through the rotor 130 between the first coil 113 and the second coil 123 due to an externally applied drive current.

[0020] The first coil cover 114 holds the first coil 113 in a predetermined position within the first case 111. The second coil cover 124 holds the second coil 123 in a predetermined position within the second case 121. A space is provided between the first coil cover 114 and the second coil cover 124 for the rotor 130.

[0021] The first stator 110 and the second stator 120 may be configured in a ring shape, or they may be configured with a portion of the ring missing. Figures 1 and 3 show an example in which the first stator 110 and the second stator 120 are configured in a semicircular shape. In addition, the first stator 110 and the second stator 120 may be in any of the following shapes: 1 / 4 circular, 1 / 3 circular, 2 / 3 circular, or 3 / 4 circular. In Figure 3, for illustrative purposes, the interior is visible at the ends of the first stator 110 and the second stator 120, but the ends of the first case 111 and the second case 121 may be sealed.

[0022] The rotor 130 is rotatably positioned in the space between the first stator 110 and the second stator 120, around a rotation axis (not shown). The rotor 130 transmits rotation to the outside through the rotation axis (not shown). The rotor 130 comprises a first annular portion 131, a second annular portion 132, a connecting portion 133, and a magnetic portion 134. The first annular portion 131 is provided on the radially inner side of the rotor 130. The second annular portion 132 is provided on the radially outer side of the rotor 130. Multiple connecting portions 133 are provided to connect the first annular portion 131 and the second annular portion 132 radially at predetermined angular intervals. The first annular portion 131, the second annular portion 132, and the connecting portion 133 are made of a non-magnetic conductor such as aluminum or copper. The rotor 130 can also be constructed by forming holes (slits) at equal angular intervals in the radial direction in a non-magnetic metal disk. The magnetic material portion 134 is provided so as to fill the region enclosed by the first annular portion 131, the second annular portion 132, and the connecting portion 133 with a soft magnetic material such as Permendur powder. The axial magnetic flux φ generated by the first coil 113 and the second coil 123 passes through the magnetic material portion 134, which has high magnetic permeability, in the rotor 130.

[0023] [Magnetic characteristics of axial gap induction motor 100] The magnetic characteristics of the axial gap induction motor 100 of Embodiment 1 will be explained using Figure 4. Figure 4 is an explanatory diagram showing the magnetic characteristics of the axial gap induction motor 100 in Embodiment 1. In Figure 4, the axial gap induction motor 100 is shown with one magnetic pole component of the first coil 113 and the second coil 123 decomposed, and the path of the magnetic flux of the rotating magnetic field at a certain timing is shown by a dashed line.

[0024] The first coil 113 and the second coil 123 become opposite in polarity due to an external drive current, and a rotating magnetic field can be generated between the first coil 113 and the second coil 123 by the axial magnetic flux passing through the rotor 130. The magnetic flux φ travels from the first coil 113 through the magnetic material portion 134 of the rotor 130 to the second coil 123. This magnetic flux φ circulates through the second core 122, travels from the second coil 123 through the magnetic material portion 134 of the rotor 130 to the first coil 113. Furthermore, this magnetic flux φ circulates through the first core 112, and travels from the first coil 113 towards the magnetic material portion 134 of the rotor 130. Driven by an external current, the above magnetic flux φ moves through multiple magnetic poles of the first coil 113 and the second coil 123, thereby forming a rotating magnetic field.

[0025] As described above, the rotating magnetic field caused by the magnetic flux φ passing through the magnetic part 134 of the rotor 130 induces an induced current to flow in the conductive path between the first annular part 131, the second annular part 132, and the connecting part 133 of the rotor 130, according to Fleming's right-hand rule. This induced current acts with the rotating magnetic field, and according to Fleming's left-hand rule, a force acts on the rotor 130, causing the rotor 130 to rotate in the axial gap induction motor 100.

[0026] [Embodiment 1 vs. Conventional Example] Conventionally, the magnetic flux was configured to circulate between the stator coils and the opposing rotor. Even in conventional axial-gap induction motors, where the rotor is sandwiched between two coils, the magnetic flux circulated between one coil and the rotor, as well as between the other coil and the rotor. In contrast, in the axial gap induction motor 100 of this embodiment, the first core 112 and the first coil 113, and the second coil 123 and the second core 122, which are arranged on both sides of the rotor 130, form an axial magnetic flux that circulates while passing through the magnetic material portion 134 of the rotor 130 in the axial direction. Therefore, the first core 112 and the first coil 113, as well as the second coil 123 and the second core 122, can form a stronger magnetic flux toward the rotor 130 than in the conventional design. As a result, an axial gap induction motor 100 that is more efficient than conventional models can be realized.

[0027] It is preferable that the number of poles M of the rotating magnetic field formed by the first coil 113 and the second coil 123, and the number of connecting parts 133 of the rotor 130 N satisfy the condition 100M ≥ N ≥ 3M. If the number of connecting parts 133 of the rotor 130 N is at least three times the number of poles M of the rotating magnetic field, then smooth rotation of the rotor 130 can be achieved due to the relationship between the induced current generated in the rotor 130 and the rotating magnetic field. By setting the number of connecting parts 133 of the rotor 130 to a maximum of 100 times the number of poles M, the relationship between the induced current generated in the rotor 130 and the rotating magnetic field makes it possible to achieve even smoother rotation of the rotor 130. In the axial gap induction motor 100, the magnetic flux formed by the first coil 113 and the second coil 123 is directed through the magnetic material portion 134 of the rotor 130 in the axial direction. Therefore, it is easier to set the number of connecting parts 133 N to be larger than in conventional induction motors, thereby achieving smooth and highly efficient rotation of the rotor 130.

[0028] When the first stator 110 and the second stator 120 are configured with a portion of the annular shape missing, a portion of the rotor 130 is exposed and not covered by the first stator 110 and the second stator 120. This promotes heat dissipation from the rotor 130. As the temperature of the rotor 130 decreases due to heat dissipation, the increase in the electrical resistance of the conductors constituting the first annular portion 131, the second annular portion 132, and the connecting portion 133 is suppressed. As a result, a sufficiently strong induced current flows through the first annular portion 131, the second annular portion 132, and the connecting portion 133 due to the rotating magnetic field caused by the magnetic flux φ passing through the magnetic material portion 134.

[0029] [Effects of Embodiment 1] The axial gap induction motor 100 of Embodiment 1 can provide the following effects. The axial gap induction motor 100 of Embodiment 1 comprises a first stator 110, a second stator 120, and a rotor 130. An axial magnetic flux can be formed between the first coil 113 and the second coil 123, passing through the rotor 130. The rotor 130 has a radially inner first annular portion 131, a radially outer second annular portion 132, and a plurality of connecting portions 133 that radially connect the first annular portion 131 and the second annular portion 132, all made of a non-magnetic conductor. A magnetic portion 134 is provided in the region surrounded by the first annular portion 131, the second annular portion 132, and the connecting portions 133. As a result, the first coil 113 and the second coil 123, which are positioned on both sides of the rotor 130, can form an axial magnetic flux that passes through the magnetic material portion 134 of the rotor 130. Therefore, the axial gap induction motor 100 can form a stronger magnetic flux toward the rotor 130 than conventional models. As a result, the axial gap induction motor 100 can be made more efficient than conventional induction motors.

[0030] In the axial gap induction motor 100 of Embodiment 1, the first stator 110 comprises a planar first core 112 and a first coil 113 provided along the first core 112 on the rotor 130 side, and the second stator 120 comprises a planar second core 122 and a second coil 123 provided along the second core 122 on the rotor 130 side. The first core 112 and first coil 113, and the second coil 123 and second core 122, which are positioned on both sides of the rotor 130, form an axial magnetic flux that circulates while passing through the magnetic material portion 134 of the rotor 130 in the axial direction. As a result, the axial gap induction motor 100 can form a stronger magnetic flux toward the rotor 130 than conventional induction motors, thanks to the first core 112 and first coil 113, and the second coil 123 and second core 122. As a result, the axial gap induction motor 100 can be made more efficient than conventional induction motors.

[0031] In the axial gap induction motor 100 of Embodiment 1, the first coil 113 and the second coil 123 are wound using a distributed winding method. This makes it possible to make the first coil 113 and the second coil 123 thinner than with concentrated winding in each slot. Furthermore, by using a distributed winding method for the first coil 113 and the second coil 123, the distance between the first core 112 and the first coil 113 and the second core 122 and the second coil 123 is shortened, making it possible to form a stronger magnetic flux than in conventional designs. As a result, the axial gap induction motor 100 can be made more efficient than conventional induction motors.

[0032] In the axial gap induction motor 100 of Embodiment 1, the first stator 110 and the second stator 120 are formed with a portion of the annular shape missing, and the rotor 130 has a region that is not covered by the first stator 110 and the second stator 120. As a result, a portion of the rotor 130 is exposed and not covered by the first stator 110 and the second stator 120, thus promoting heat dissipation. As the temperature of the rotor 130 decreases due to heat dissipation, the increase in the electrical resistance of the conductors constituting the first annular portion 131, the second annular portion 132, and the connecting portion 133 is suppressed. As a result, an induced current of sufficient strength flows through the first annular portion 131, the second annular portion 132, and the connecting portion 133 due to the rotating magnetic field caused by the magnetic flux φ passing through the magnetic material portion 134, making it possible to make the axial gap induction motor 100 more efficient than conventional induction motors.

[0033] In the axial gap induction motor 100 of Embodiment 1, it is preferable that the number of poles M of the rotating magnetic field formed by the first coil 113 and the second coil 123 and the number of connecting parts 133 of the rotor 130 satisfy 100M ≥ N ≥ 3M. If the number of poles M of the rotating magnetic field and the number of connecting parts 133 N are at least 3 times the number of poles M, then smooth rotation of the rotor 130 can be achieved due to the relationship between the induced current generated in the rotor 130 and the rotating magnetic field. By setting the number of connecting parts 133 N to a maximum of 100 times the number of poles M, even smoother rotation of the rotor 130 can be achieved due to the relationship between the induced current generated in the rotor 130 and the rotating magnetic field. As a result, in the axial gap induction motor 100, the magnetic flux formed by the first coil 113 and the second coil 123 is directed through the magnetic material portion 134 of the rotor 130 in the axial direction. Therefore, it becomes easier to set a larger number of coupling portions 133 N than in conventional induction motors and achieve smooth rotation of the rotor 130. [Explanation of Symbols]

[0034] 100 Axial gap induction motor, 110 First stator, 111 First case, 111a First planar section, 111b First outer cylinder section, 111c First inner cylinder section, 112 First core, 113 First coil, 114 First coil cover, 120 Second stator, 121 Second case, 121a Second planar section, 121b Second outer cylinder section, 121c Second inner cylinder section, 122 Second core, 123 Second coil, 124 Second coil cover, 130 Rotor, 131 First annular section, 132 Second annular section, 133 Connecting section, 134 Magnetic section, M Number of poles of the rotating magnetic field, N Number of connecting sections, φ Magnetic flux.

Claims

1. A planar first stator (110) equipped with a first coil (113), A planar second stator (120) is provided with a second coil (123) and is positioned opposite the first stator (110), The system comprises a planar rotor (130) rotatably disposed between the first stator (110) and the second stator (120), An axial magnetic flux passing through the rotor (130) can be formed between the first coil (113) and the second coil (123). The rotor (130) includes: The radially inner first annular portion (131), the radially outer second annular portion (132), and the plurality of connecting portions (133) that radially connect the first annular portion (131) and the second annular portion (132) are made of a non-magnetic conductor. A magnetic material portion (134) is provided in the region enclosed by the first annular portion (131), the second annular portion (132), and the connecting portion (133). Axial gap induction motor.

2. The first stator (110) comprises a planar first core (112) and a first coil (113) provided along the first core (112) on the rotor (130) side. The second stator (120) comprises a planar second core (122) and a second coil (123) provided along the second core (122) on the rotor (130) side. The axial gap induction motor according to claim 1.

3. The first coil (113) and the second coil (123) are wound by a distributed winding. The axial gap induction motor according to claim 2.

4. The first stator (110) and the second stator (120) are formed in a shape with a part of the ring missing, The rotor (130) has a region that is not covered by the first stator (110) and the second stator (120). The axial gap induction motor according to claim 1.

5. When M is the number of poles of the rotating magnetic field formed in the first coil (113) and the second coil (123), and N is the number of connecting parts (133), then 100M ≥ N ≥ 3M is satisfied. An axial gap induction motor according to any one of claims 1 to 4.

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