Single-pole motor

Abstract

To provide a practical single-pole motor capable of operating with a DC power supply as an energy source.SOLUTION: A single-pole motor includes a stator 10 and a rotor 20. The stator 10 has an annular core 30 made of a magnetic material and a coil 40 in which a coil wire 42 is toroidally wound around the core 30. The rotor 20 has an annular shape around a rotation axis AX, has different poles from each other on a first main surface and a second main surface perpendicular to a thickness direction, and includes: a permanent magnet 50 disposed such that the first main surface faces the coil 40; and a yoke 60 disposed on the second main surface side so as to be in contact with a second main surface 52 of the permanent magnet 50. The coil 40 is configured such that current flows through each of the coil wires 42 facing the permanent magnets 50 in a first direction D1, and current flows through each of the coil wires 42 located on a side opposite to a side on which the permanent magnet 50 is disposed in a second direction D1 opposite to the first direction D2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a homopolar motor. [Background technology]

[0002] A well-known electromechanical device that uses a direct current (DC) power source as an energy source to rotate an object is the homopolar motor (unipolar motor), the principle of which was discovered by Faraday long ago. The basic principle of a unipolar motor is based on Fleming's left-hand rule, which states that a force is generated in a conductor wire when a current is passed through the conductor wire in a magnetic field (see, for example, Non-Patent Document 1).

[0003] Since then, a wide variety of motors and actuators that use DC power as their energy source have been developed, and are still in use today. For example, the DC motors that are widely used today have a mechanism in which the coils wound with wire are divided into several phases, and the rotor is rotated by switching the phase for each coil. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Masahito Nakagawa, "Operating Principle of a Unipolar Motor," Journal of the Japan Society of Physics Education, Vol. 2, 2007, pp. 141-144. Summary of the Invention [Problem to be solved by the invention]

[0005] However, today's DC motors will not rotate unless the current flowing through the coils corresponding to each phase is appropriately switched, for example, using brushes and commutators in the case of brushed DC motors, or using a drive circuit with Hall elements and electronic circuits in the case of brushless DC motors.

[0006] On the other hand, a unipolar motor can rotate with a relatively simple configuration, as described in Non-Patent Document 1. However, such well-known classical unipolar motors are experimentally based and are not practical.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a practical unipolar motor that can operate using a DC power supply as its energy source. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a unipolar motor including a stator and a rotor. The stator has an annular core made of a magnetic material and a coil formed by toroidally winding a coil wire around the core. The rotor is annular about the rotation axis and has a first main surface perpendicular to the thickness direction and a second main surface opposite the first main surface, each of which has a different polarity. The rotor has a permanent magnet arranged so that the first main surface faces the coil, and a yoke disposed on the second main surface side of the permanent magnet so as to contact the second main surface. The unipolar motor is configured so that a current flows in a first direction through each coil wire facing the permanent magnet, and a current flows in a second direction opposite to the first direction through each coil wire located opposite the side where the permanent magnet is located. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a practical unipolar motor that can operate using a DC power supply as an energy source. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a unipolar motor 1 according to a first embodiment. [Figure 2] 2 is a cross-sectional view of the unipolar motor 1 according to the first embodiment taken along an imaginary plane PL1 shown in FIG. 1 and viewed along an arrow P1. [Figure 3] 2 is a cross-sectional view of the unipolar motor 1 according to the first embodiment taken along an imaginary plane PL2 shown in FIG. 1 and viewed along an arrow P2. [Figure 4] 1 is a perspective view showing a core 30 and a coil 40 of the first embodiment. [Figure 5] 3 is a diagram showing a wire connection state of a coil 40 in the first embodiment. FIG. [Figure 6] 1 is a cross-sectional view illustrating the operation of the unipolar motor 1 according to the first embodiment. [Figure 7] FIG. 10 is a cross-sectional view of a unipolar motor 2 according to a second embodiment. [Figure 8] 10 is a diagram for explaining a unipolar motor 3 according to a third embodiment. FIG. [Figure 9] FIG. 10 is a perspective view illustrating a method for constructing a stator 10D according to a fourth embodiment. [Figure 10] FIG. 10 is a perspective view of a stator 10D according to a fourth embodiment. [Figure 11] FIG. 10 is a cross-sectional view of a unipolar motor 4 according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes a unipolar motor according to the present invention with reference to the drawings. Note that the same reference numerals in the drawings are omitted from the following drawings, since the same explanations can be applied to the other drawings. Also, in later drawings, the reference numerals may be omitted for parts that have already been indicated and explained in the previous drawings. In this specification and drawings, magnetic flux Φ may be referred to as Flux, and vectors representing the direction of magnetic flux may be referred to as magnetic lines of force. Furthermore, magnetic flux per unit area may be referred to as magnetic flux density B.

[0012] [Embodiment 1] 1. Configuration of the unipolar motor 1 according to the first embodiment (1) Overview of Unipolar Motor 1 Fig. 1 is a perspective view of a unipolar motor 1 according to embodiment 1. As shown in Fig. 1, the unipolar motor 1 is broadly composed of a stator 10 and a rotor 20. The unipolar motor 1 is a motor in which the rotor 20 rotates around a rotation axis AX, and is different in nature from motors such as voice coil motors in which a cylindrical coil moves linearly back and forth along the central axis of the cylinder.

[0013] The unipolar motor 1 is a type of electromechanical device that uses a direct current (DC) power source as an energy source to rotate a rotor 20. Here, the term "unipolar motor" refers to a motor that can rotate using only one set of permanent magnets with N and S magnetic poles.

[0014] In the unipolar motor 1 according to the first embodiment, an air gap AG1 that forms part of an effective area ER (defined later) is provided in the radial direction RD centered on the rotating axis AX, making the unipolar motor 1 a so-called radial gap motor. In addition, in the unipolar motor 1, the rotor 20 is positioned relatively outward from the rotating axis AX, making it a so-called outer rotor type motor.

[0015] FIG. 2 is a cross-sectional view of the unipolar motor 1 according to the first embodiment, taken along imaginary plane PL1 in FIG. 1 and viewed along arrow P1. A circle with a black dot in the coil wire 42 indicates a current flowing from the rear side to the front side of the page, and a circle with an X indicates a current flowing from the front side to the rear side of the page (the same applies to the following drawings). FIG. 3 is a cross-sectional view of the unipolar motor 1 according to the first embodiment, taken along imaginary plane PL2 in FIG. 1 and viewed along arrow P2. In each drawing, the core protrusion 34 is not visible in the cross section but is depicted in solid lines in the foreground or background. In FIG. 3, the lower half of the motor from the rotation axis AX is not shown because it has the same configuration as the upper half. FIG. 4 is a perspective view of the core 30 and coil 40 according to the first embodiment. FIG. 5 is a diagram showing the connection state of the coil 40 according to the first embodiment.

[0016] 2 and 3, the stator 10 has a core 30 and a coil 40, and a coil wire 42 is toroidally wound around the annular core 30. The rotor 20 has a permanent magnet 50 and a yoke 60.

[0017] (2) Core 30 and coil 40 (stator 10) (2-1) Core 30 As shown in Fig. 4, the core 30 has an annular shape (see also Fig. 2). The annular shape here refers to a shape that has a hole in a region near the center, including the position of the rotation axis AX, and is continuous over 360° around the rotation axis AX. Specifically, the core 30 of the first embodiment has a hollow cylindrical shape.

[0018] The core 30 has a core body 32. The core body 32 refers to the portion of the core 30 around which at least the coil wire 42 is wound.

[0019] The dimension in the direction in which the coil wire 42 runs on the surface (outer peripheral surface) of the core body 32 facing the permanent magnet 50 is defined as the "coil winding width WC." For reference, in the core 30 of embodiment 1, the dimension in the direction in which the coil wire 42 runs on the surface (inner peripheral surface) opposite the surface facing the permanent magnet 50 also has the same width as the coil winding width WC (see FIG. 3). Note that it is not necessary for all of the coil wires 42 to run in the same direction in the strict sense, and in that sense, the "direction in which the coil wire 42 runs" here can be an approximate direction.

[0020] On the other hand, the "width WM of the permanent magnet" is the dimension of the permanent magnet 50 corresponding to the coil winding width WC of the core body 32. Specifically, in the radial gap motor of the first embodiment, the dimension of the permanent magnet 50 in the direction along the rotation axis AX is defined as the "width WM of the permanent magnet" (see FIG. 3). Note that in the unipolar motor 3 (axial gap motor) according to a third embodiment described below, the dimension of the permanent magnet 50 in the radial direction is defined as the "width WM of the permanent magnet" (see FIG. 8(a) described below).

[0021] It is preferable that the coil winding width WC is set slightly larger than the width WM of the permanent magnet. Assuming that all magnetic flux emerges perpendicularly from the first main surface 51 (described below) of the permanent magnet 50, by setting the coil winding width WC slightly larger than the width WM of the permanent magnet, the magnetic flux emerging perpendicularly and parallel from the first main surface 51 of the permanent magnet 50 can be made to intersect only at the straight portions of the coil wire 42, without intersecting at the curved portions of the coil wire 42.

[0022] In this specification, the region where the magnetic flux from the permanent magnet 50 enters substantially perpendicularly and where the coil wire 42 is wound (including the air gap AG1 nearby) is referred to as the "effective region ER."

[0023] (2-2) Core protrusion 34 and slot 36 The core 30 is provided with a core protrusion 34. The core protrusion 34 is a portion that protrudes outward from the core body 32 beyond the coil winding width WC. The core protrusions 34 are provided at a plurality of discrete locations on a circumference centered on the rotation axis AX. In the example shown in the figure, 12 core protrusions 34 are provided at 30° intervals on the circumference of both bottom surfaces (both ends) of a cylinder centered on the rotation axis AX. The core protrusions 34 in the first embodiment are provided integrally with the core body 32. However, this is not limited thereto, and the core protrusions 34 may be separate from the core body 32 but connected to the core body 32.

[0024] The core 30, including the core body 32 and the core protrusions 34, is made of a magnetic material. This allows the magnetic flux generated by the permanent magnets 50 to be drawn into the core 30, preventing the magnetic flux from leaking to the coil wire 42 (the coil wire 42 on the inner peripheral surface side) located on the opposite side from the side where the permanent magnets 50 are arranged (see also FIG. 6). The magnetic flux drawn into the core 30 at high density passes through the core protrusions 34 at both ends of the core 30, and then passes through the air gap AG2 (described later) to the yoke protrusions 64 and returns to the rotor 20 side.

[0025] In the unipolar motor 1 according to the first embodiment, a slot 36 is formed between adjacent core protrusions 34.

[0026] (2-3) Coil 40 The coil 40 is formed by toroidally winding a coil wire 42 around the core 30. In the first embodiment, the coil 40 is formed by winding the coil wire 42 around the slots 36.

[0027] Here, "toroidal winding" refers to a winding method in which the coil wire 42 is wound around the annular core 30, passing alternately between the inner circumferential side (the side facing the opening) and the outer circumferential side of the core 30. The coil wires 42 on the outer circumferential surface of the core 30 (the coil wires 42 facing the permanent magnet 50) are wound generally parallel to each other along the coil winding width WC. Similarly, the coil wires 42 on the inner circumferential surface of the core 30 are wound generally parallel to each other. When a predetermined number of turns of the coil wire 42 are wound in one slot 36, the coil wire 42 transfers to the adjacent slot 36 via a bridge portion 42a on the inner circumferential surface. In this way, the coil 40 is configured such that one coil wire 42 passes continuously through multiple slots 36 to connect between terminals 44a (DCa) and 44b (DCb).

[0028] In the unipolar motor 1 according to the first embodiment, a gap (constituting part of the air gap AG1) between the first main surface 51 of the permanent magnet 50 and the coil wire 42 facing the first main surface 51 is provided in the radial direction about the rotation axis AX. It is desirable that the distance between the opposing gaps is approximately the same.

[0029] (2-4) Other configurations on the stator 10 side The core 30 is attached to a stator fixing portion 81, which is attached to a shaft 80. The stator fixing portion 81 is also connected to the inner diameter side of a bearing 84. The two stator fixing portions 81, one on the left and one on the right, are spaced apart with a spacer 82 in between. The yoke 60 is connected to the outer diameter side of the bearing 84 via a rotor cap 86 (see FIG. 3).

[0030] (3) Permanent magnet 50 and yoke 60 (rotor 20) 2 and 3, the rotor 20 will be described. The rotor 20 has a permanent magnet 50 and a yoke 60.

[0031] (3-1) Permanent magnet 50 The permanent magnet 50 has an annular shape centered on the rotation axis AX, and has opposite poles (north and south poles) on a first main surface 51 perpendicular to the thickness direction and a second main surface 52 opposite the first main surface 51. Specifically, the permanent magnet 50 of the first embodiment is cylindrical, and is a so-called radially anisotropic magnet, in which, for example, an north pole is arranged on the first main surface 51 (inner peripheral surface) perpendicular to the thickness direction of the side portion, and an south pole is arranged on the second main surface 52 (outer peripheral surface). This cylindrical permanent magnet 50 does not necessarily have to be a single unit, and may be made by bonding sector-shaped permanent magnets together into a cylindrical shape. In this specification, the term "main surface" refers to a main surface that is much larger in area than the other surfaces that make up the thin plate.

[0032] The permanent magnet 50 is arranged so that the first main surface 51 faces the coil 40, and is also arranged coaxially so that the central axis of the permanent magnet 50 coincides with the central axes of the core 30 and the coil 40.

[0033] (3-2) York 60 The yoke 60 is mainly made of a soft magnetic material, and is disposed on the second main surface 52 side of the permanent magnet 50 so as to be in contact with the second main surface 52 of the permanent magnet 50 .

[0034] The yoke 60 has a yoke body 62. The yoke body 62 refers to the portion of the yoke 60 that overlaps with the permanent magnet 50. The yoke 60 also has a yoke protrusion 64. The yoke protrusion 64 is connected to the yoke body 62 and refers to the portion that protrudes outward from the yoke body 62 beyond the width WM of the permanent magnet (see FIG. 3). The yoke protrusion 64 is preferably formed integrally with the yoke body 62, but may be separate from the yoke body 62 as long as it is tightly connected and continuous as a magnetic circuit.

[0035] Additionally, yoke protrusion 64 has a bent portion 65 at its end that is bent in a direction perpendicular to first main surface 51. The term "bent" includes concepts such as curvature and protrusion. Yoke protrusion 64 including bent portion 65 and core protrusion 34 face each other across a radial gap at bent portion 65 (see FIG. 3).

[0036] The bent portion 65 is included as part of the concept of the yoke protrusion 64. The bent portion 65 is preferably formed integrally with the straight portion of the yoke protrusion 64 (the straight portion that protrudes as a continuation of the yoke body 62), but may be a separate body as long as it is tightly connected and continuous as a magnetic circuit.

[0037] (4) Magnetic circuit configuration Because the unipolar motor 1 has the structure described above, it forms a single closed "magnetic circuit (flux path)" (see FIGS. 3 and 6). In this case, the magnetic circuit uses the permanent magnet 50 as a magnetomotive force source and is formed by the path of the first magnetic pole (North pole in the figures) arranged on the first main surface 51 of the permanent magnet 50, the air gap AG1 corresponding to the effective area ER, the core body 32, the core protrusion 34, the air gap AG2, the bent portion 65 of the yoke protrusion 64, the straight portion of the yoke protrusion 64, the yoke body 62, and the second magnetic pole (South pole in the figures) arranged on the second main surface 52 of the permanent magnet 50.

[0038] In the first embodiment, the air gap AG2 is configured to face the bent portion 65 of the yoke protrusion 64. However, the present invention is not limited to this. A similar configuration may be achieved by providing the bent portion 35 in the core protrusion 34 (see FIG. 7 in a second embodiment described later), or the air gap AG2 may be sandwiched between the bent portions 35, 65 in both the core protrusion 34 and the yoke protrusion 64 (see FIG. 8 in a third embodiment described later).

[0039] In this case, it is preferable that the air gap AG2 is provided with a gap in the radial direction RD. That is, it is preferable that the core protrusion 34 and the yoke protrusion 64 have bent portions 35, 65 bent in a direction perpendicular to the first main surface 51 at at least one end thereof, and that the core protrusion 34 and the yoke protrusion 64 face each other at the bent portions 35 and / or 65 with a gap in the radial direction RD between them. It is desirable that the gaps be approximately the same at each location on the opposing surfaces.

[0040] (5) Wiring and current drive of the coil 40 As shown in FIG. 5, the coil 40 has one coil wire 42 that passes continuously through a plurality of slots 36 to connect between a terminal 44a (DCa) and a terminal 44b (DCb).

[0041] In the unipolar motor 1, it is not necessary to switch the direction of current for each phase in order to rotate the rotor 20, and it is basically sufficient to pass a direct current in a single direction through the coil 40 as a whole. For example, by applying a DC voltage with a positive potential DCa to terminal 44a and a negative potential DCb to terminal 44b, a unidirectional current i flows through the coil 40. At this time, because the coil wire 42 is toroidally wound, a current flows in a first direction D1 through each coil wire 42 facing the permanent magnet 50 (each coil wire on the outer diameter side), and a current flows in a second direction D2 opposite to the first direction D1 through each coil wire 42 located on the opposite side from where the permanent magnet 50 is arranged (each coil wire on the inner diameter side) (see FIGS. 2, 4, and 6).

[0042] 2. Effects of the Unipolar Motor 1 According to the First Embodiment Figure 6 is a cross-sectional view illustrating the operation of the unipolar motor 1 according to the first embodiment. Figure 6(a) is a view corresponding to Figure 3, and Figure 6(b) is an enlarged cross-sectional view of the portion surrounded by dashed line A in Figure 6(a). Symbol B indicates magnetic flux density, symbol i indicates the current flowing through the coil wire 42, symbol F indicates the force acting on the coil wire 42, and symbol ROT indicates the force acting to rotate the permanent magnet 50 (on the rotor 20 side) as a reaction force to the force acting on the coil wire 42 (on the stator 10 side).

[0043] (1) In the unipolar motor 1 according to the first embodiment, the permanent magnet 50 in the rotor 20 is annular, has a first main surface 51 and a second main surface 52 with different poles, and is disposed so that the first main surface 51 faces the coil 40. In addition, the yoke 60 is disposed on the second main surface 52 side of the permanent magnet 50 so as to be in contact with the permanent magnet 50. On the other hand, the stator 10 has a core 30 and a coil 40 formed by toroidally winding a coil wire 42 around the core 30, with a portion of the coil wire 42 facing the permanent magnet 50 (first main surface 51 of the permanent magnet 50).

[0044] 6(a), the above-mentioned "magnetic circuit" is formed in the unipolar motor 1. In other words, with the permanent magnet 50 as the magnetomotive force source, magnetic flux circulates through a path that crosses the first main surface 51 of the permanent magnet 50 and the coil wire 42, the air gap AG1, the inside of the core 30, both ends of the core 30 (e.g., the core protrusion 34), both ends of the yoke 60 (e.g., the yoke protrusion 64), the main body of the yoke 60, and the second main surface 52 of the permanent magnet 50.

[0045] Next, from the viewpoint of current, in the unipolar motor 1, the coil 40 is formed by winding the coil wire toroidally around the annular core. Therefore, when a DC voltage is applied from a terminal 44a on one end of the coil wire 42 to a terminal 44b on the other end of the coil wire 42 by a DC power supply, current flows in the first direction D1 through each coil wire 42 facing the permanent magnet 50.

[0046] However, near the air gap AG1, a high-density, parallel magnetic flux passes substantially perpendicular to the first main surface 51. For example, in FIG. 6(b), magnetic flux density B passes from the top to the bottom of the drawing (the opposite direction to the radial direction RD). Furthermore, in each coil wire 42 facing the first main surface 51, a direct current flows in a first direction D1 substantially parallel to the first main surface 51.

[0047] As described above, the unipolar motor 1 according to the first embodiment is configured so that a current i flows in a predetermined direction through the coil wire 42 placed in a field through which magnetic flux (magnetic flux density B) passes, and therefore, according to Fleming's left-hand rule, the coil wire 42 is subjected to a force F. For example, in the example shown in the figure, the coil wire 42 is subjected to the force F in the direction from the back of the page to the front of the page. However, because the coil wire 42 belongs to the stator 10 and is fixed, the force F that the coil wire receives is transferred as a reaction force to a force ROT that moves the rotor 20. In this way, the rotor 20 is able to rotate by receiving the force ROT.

[0048] Therefore, in the unipolar motor 1 according to the first embodiment, the rotor 20 can be rotated simply by passing a unidirectional DC current i through the coil wire 42. Furthermore, according to Fleming's left-hand rule, the direction of rotation can be reversed by reversing the direction of the current i. The rotation speed can also be changed by changing the magnitude of the current i. Furthermore, the rotational torque can be appropriately set or changed by changing the number of turns of the coil 40, the magnetomotive force of the permanent magnet 50, the size of the air gaps AG1 and AG2, etc.

[0049] In this way, the unipolar motor 1 can rotate appropriately simply by passing a DC current in one direction, eliminating the need for a commutator, Hall elements, or special electronic circuits for switching current for each phase, resulting in a simple structure and configuration that is also economically advantageous.In addition, cogging and torque ripple during rotation, which occur due to current switching for each phase, do not occur, and smooth rotation characteristics can be achieved.

[0050] Furthermore, in the multi-pole motors that are prevalent today, the direction of the magnetic field inside the core changes when the rotor, which has multi-pole permanent magnets, rotates at high speed and when the direction of the current flowing through the coils changes, which inevitably generates eddy current loss and hysteresis loss (so-called iron loss), resulting in reduced energy efficiency.To mitigate this issue, measures such as using laminated silicon steel sheets for the soft magnetic materials that make up the magnetic circuits, such as the core, have been necessary. On the other hand, in the unipolar motor 1 according to embodiment 1, the direction of the magnetic field in the core 30 does not change even when the rotor 20 rotates, and there is no need to switch the direction of the current flowing in the coil 40. Therefore, the motor is highly energy-efficient and does not generate iron loss, etc., even without using the special soft magnetic materials described above.

[0051] As described above, according to the first embodiment, it is possible to provide a practical unipolar motor 1 that can operate using a DC power supply as an energy source.

[0052] (2) In the unipolar motor 1 according to embodiment 1, core protrusions 34 that protrude outward from the core body 32 beyond the coil winding width WC are provided at multiple discrete locations on a circumference centered on the rotation axis AX. This configuration allows the magnetic path in the core 30 to be expanded further outward from the region of the coil winding width WC. Therefore, the magnetic flux taken into the core 30 from the permanent magnet 50 can be released (passed) to the core protrusion 34 on the outside beyond the coil winding width WC, making it easier to pass the magnetic flux to and from the rotor 20.

[0053] (3) In the unipolar motor 1 according to embodiment 1, a yoke protrusion 64 is provided which is connected to the yoke body 62, which is the part that overlaps with the permanent magnet 50, and which protrudes outward from the yoke body 62 beyond the width WM of the permanent magnet. This configuration allows the magnetic path in the yoke 60 to be expanded further outward from the region of the width WM of the permanent magnet. Therefore, the magnetic flux returning to the permanent magnet 50 via the yoke body 62 can be received by the outer yoke protrusion 64 that exceeds the width WM of the permanent magnet, making it easier to exchange magnetic flux with the stator 10.

[0054] Furthermore, it is preferable that the yoke protrusion 64 is disposed so as to face the core protrusion 34 across the air gap AG2. It is also more preferable that the area of ​​the opposing portions is relatively large. This configuration increases the permeance in the air gap AG2 (reduces magnetic resistance), making it possible to pass more magnetic flux at high density, resulting in a motor with high torque.

[0055] [Embodiment 2] 7 is a cross-sectional view of a unipolar motor 2 according to embodiment 2. This figure is a cross-sectional view corresponding to FIG.

[0056] The unipolar motor 2 according to the second embodiment has basically the same configuration as the unipolar motor 1 according to the first embodiment, but differs from the unipolar motor 1 according to the first embodiment in the positional relationship of the rotors. That is, the unipolar motor 2 according to the second embodiment is a so-called inner rotor type motor in which the rotor 20B is arranged on the inside close to the rotation axis AX and the stator 10B is arranged on the outside far from the rotation axis AX.

[0057] (1) As shown in Fig. 7, the permanent magnets 50B and yoke 60B that constitute the rotor 20B are integrally fixed to the shaft 80. The core 30B and coil 40B that constitute the stator 10B are disposed on the outside of the rotor 20B at a position relatively far from the rotation axis AX. A stator fixing part 81B to which the core 30B is attached is connected to the outer diameter side of the bearing 84.

[0058] (2) The core protrusion 34B has a bent portion 35B at its end that is bent in a direction perpendicular to the first main surface 51B. This bent portion 35B is included in the concept of the core protrusion 34B. The bent portion 35B is preferably formed integrally with the straight portion of the core protrusion 34B (the straight portion that protrudes as a continuation of the core body 32B), but may be a separate body as shown in FIG. 7 as long as it is tightly connected and continuous as a magnetic circuit. The core protrusion 34B including the bent portion 35B and the yoke protrusion 64B face each other across a radial gap (air gap AG2B) at the bent portion 35B.

[0059] The unipolar motor 2 according to the second embodiment is configured on the same principle as the unipolar motor 1 according to the first embodiment, except for the positional relationship of the rotors. Therefore, the unipolar motor 2 according to the second embodiment has the same effects as the unipolar motor 1 according to the first embodiment.

[0060] [Embodiment 3] 8A and 8B are diagrams illustrating a unipolar motor 3 according to a third embodiment. FIG. 8A is a diagram of the stator 10C and the rotor 20C as viewed along the rotation axis AX, and FIG. 8B is a side view of the stator 10C and the rotor 20C as viewed along the arrow P3 cut at the imaginary plane PL3 shown in FIG. 8A. FIG. 8B is a cross-sectional view taken along the arrow BB in FIG. 8A. However, the core protrusion 34 is not visible in cross section but is shown as a background. FIG. 8C is an enlarged cross-sectional view of the main parts of FIG. 8B.

[0061] The unipolar motor 3 according to the third embodiment basically has the same configuration as the unipolar motors 1 and 2 according to the first and second embodiments, but differs from the unipolar motors 1 and 2 according to the first and second embodiments in the way in which the air gap between the permanent magnet side and the coil side is provided. That is, in the unipolar motor 3 according to the third embodiment, the gap (forming part of the air gap AG1C) between the first main surface 51C of the permanent magnet 50C and the coil wire 42 facing the first main surface 51C is provided in the axial direction parallel to the rotation axis AX, making it a so-called axial gap motor.

[0062] (1) As shown in FIGS. 8(a) to 8(c), the core 30C of the third embodiment is substantially annular with an opening in the center of the substantially circular plate. The central axis of the annular core 30C coincides with the rotation axis AX. The main surface of the core 30C is perpendicular to the rotation axis AX (see FIG. 8(b)). The core protrusion 34C is a portion that protrudes in the radial direction (outward) beyond the coil winding width WC of the core body 32C. Of the coil wire 42 wound around the core 30C, the first direction D1, which is the direction of current flowing in the coil wire facing the permanent magnet 50C, is parallel to the radial direction in the illustrated example.

[0063] On the other hand, the permanent magnet 50C also has a substantially annular shape, and the first and second main surfaces 51C, 52C of the permanent magnet 50C are also perpendicular to the rotation axis AX. The yoke 60C here has a substantially circular plate shape and is disposed on the second main surface 52C side of the permanent magnet 50C so as to be in contact with the second main surface 52C.

[0064] (2) In the unipolar motor 3 according to the third embodiment, two sets of permanent magnets 50C and yokes 60 are arranged on either side of the core 30C and coil 40C. The permanent magnets 50C on both sides are arranged with the same poles (north poles in the figure) facing each other toward the coil 40C.

[0065] In this way, by placing permanent magnets 50C on both sides of the core 30C and coil 40C, the magnetomotive force source is doubled, the magnetic flux density passing through the magnetic circuit of the unipolar motor 3 can be increased, and various characteristics such as torque characteristics can be further improved.

[0066] (3) In the unipolar motor 3 according to the third embodiment, the core 30C and the yoke 60C have a core protrusion 34C and a yoke protrusion 64C, respectively, as in the first and second embodiments. The core protrusion 34C and the yoke protrusion 64C each have a bent portion 35C, 65C at the end thereof that is bent in a direction perpendicular to the first main surface 51C. The bent portion of the core 30C is cylindrical and separate from the core protrusion 34C (here, a straight portion), and is connected at its inner circumferential surface to each of the core protrusions 34C arranged circumferentially.

[0067] In the unipolar motor 3 according to the third embodiment, the core protrusion 34C including the bent portion 35C and the yoke protrusion 64C including the bent portion 65C face each other across a radial gap (air gap AG2C) at the bent portions 35C and 65C. It is desirable that the distance between the radial gaps be approximately the same at each point on the opposing surfaces.

[0068] Generally, when magnetic flux passes through a relatively large air gap spaced relatively close to one another, an attractive force acts between the walls of the air gap. If the air gap AG2C were configured in the thrust direction (axial direction), this attractive force would be directly applied to the bearing load in the thrust direction, which could be detrimental to stable rotation. On the other hand, in the unipolar motor 3 according to the third embodiment, although it is an axial gap motor, the air gap AG2C between the core protrusion 34C and the yoke protrusion 64C is configured as a radial gap, which disperses the attractive force in the radial direction and contributes to stable rotation.

[0069] Except for the method of providing the air gap between the permanent magnet side and the coil side, the unipolar motor 3 according to the third embodiment is configured on the same principle as the unipolar motors 1 and 2 according to the first and second embodiments. Therefore, the unipolar motor 3 according to the third embodiment has the same effects as the unipolar motors 1 and 2 according to the first and second embodiments.

[0070] [Embodiment 4] Fig. 9 is a perspective view illustrating a method for constructing a stator 10D according to embodiment 4. Fig. 10 is a perspective view of a stator 10D according to embodiment 4. Fig. 11 is a cross-sectional view of a unipolar motor 4 according to embodiment 4, corresponding to Fig. 3.

[0071] The unipolar motor 4 according to the fourth embodiment basically has the same configuration as the unipolar motors 1 and 2 according to the first and second embodiments, but differs from the unipolar motors 1 and 2 according to the first and second embodiments in the configuration of the core and coil. That is, the core 30D according to the fourth embodiment is a split core that can be split into split core pieces 31 when the coil wire 42 is wound therearound. In other words, the core 30D according to the fourth embodiment is formed by combining a plurality of split core pieces 31.

[0072] (1) As shown in Figures 9 and 10, the split core pieces 31 are formed by cutting a cylindrical core 30D with a circumference of 360° at the positions of the core protrusions 34D and dividing it into an appropriate natural number of parts such as two, three, four, etc. In this case, each split core piece 31 does not have a region surrounded by a member, such as a hole in an annular body, in terms of topological geometry, and the entire surface on which the coil wire 42 should be wound is open. This makes it easier to wind the coil wire 42 and improves mass productivity.

[0073] After the coil wire 42 is wound around each split core piece 31, the split core pieces 31 are connected to each other at their core connection surfaces 38 so that the magnetic circuit is closely continuous, thereby completing the core 30D, and the coil 40D can be completed by connecting the coil wire 42 wound around each split core piece 31. This makes it possible to obtain a stator 10D (see FIG. 10) that is composed of a core 30D and a coil 40D that are equivalent to the unsplit core and coil (see embodiments 1 and 2).

[0074] (2) As shown in FIG. 11, although the core 30D of the fourth embodiment is a split type, the unipolar motor 4 constructed using this core can basically be configured in the same manner as the unipolar motors 1 and 2 of the first and second embodiments.

[0075] 9 to 11 show a configuration in which only two core protrusions 34 are provided. By reducing the number of core protrusions 34 in this way, the number of windings of the coil wire 42 can be increased, enabling improved torque, and the number of slots can be reduced, improving the winding efficiency of the coil wire 42 and further improving mass productivity.

[0076] Except for the configuration of the core and coil, the unipolar motor 4 according to the fourth embodiment is configured on the same principle as the unipolar motors 1 and 2 according to the first and second embodiments. Therefore, the unipolar motor 4 according to the fourth embodiment has the same effects as the unipolar motors 1 and 2 according to the first and second embodiments.

[0077] The split core and coil configuration of the fourth embodiment can also be introduced into the core 30C of the axial gap motor of the third embodiment, and in this case too, the same effects as those described above can be achieved.

[0078] Although the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment and can be embodied in various forms without departing from the spirit of the present invention, and for example, the following modifications are also possible.

[0079] Although each embodiment and modification has been described with respect to a unipolar motor, the present invention is not limited to this. The present invention can also be understood as a device that performs electromechanical conversion. By replacing "unipolar motor" with "generator" in the description of each embodiment and modification, the present invention can also be understood as a generator, and such a generator is also treated as equivalent to the present invention. [Explanation of symbols]

[0080] 1, 2, 3, 4... Unipolar motor, 10, 10B, 10C, 10D... Stator, 20, 20B, 20C, 20D... Rotor, 30, 30B, 30C, 30D... Core, 31... Divided core piece, 32, 32C... Core body, 34, 34C, 34D... Core protrusion, 35, 35B, 35C... (Core protrusion) bending portion, 36... Slot, 38... Core connection surface, 40, 40B, 40D... Coil, 42... Coil wire, 42a... (Coil wire) jumper portion, 44a, 44b... Terminal, 50, 50B, 50C... Permanent magnet, 51, 51C... First main surface, 52, 52C... Second main surface, 60, 60B, 60C... Yoke, 62... Yoke body, 64, 64C... Yoke protrusion, 65, 65C... Bending portion (of yoke protrusion), 80... Shaft, 81, 81B... Stator fixing portion, 82... Spacer, 84... Bearing, 86... Rotor cap, AG1, AG1C, AG2, AG2C... Air gap, AX... Rotating axis, B... Magnetic flux density, D1... First direction, D2... Second direction, F... Force acting on coil wire, RD... Radial direction, ROT... Force acting on rotor, WC... Coil winding width, WM... Width of permanent magnet, i... Current flowing through coil wire, Φ, Flux... Magnetic flux

Claims

1. A homopolar motor having a stator and a rotor, The stator includes: an annular core made of a magnetic material; a coil formed by winding a coil wire toroidally around the core, The rotor is a permanent magnet having an annular shape centered on the rotation axis, a first main surface perpendicular to the thickness direction, and a second main surface opposite to the first main surface, each having a polarity different from each other, and arranged so that the first main surface faces the coil; a yoke disposed on the second main surface side of the permanent magnet so as to be in contact with the second main surface, In the coil, a current flows in a first direction through each of the coil wires facing the permanent magnet, and a current flows in a second direction opposite to the first direction through each of the coil wires positioned on the opposite side to the side where the permanent magnet is disposed. A unipolar motor characterized by:

2. 2. The homopolar motor according to claim 1, When the portion of the core around which the coil wire is wound is defined as a core body, and the dimension of the surface of the core body facing the permanent magnet in the direction in which the coil wire runs is defined as a coil winding width, The core has a plurality of core protrusions that protrude outward from the core body beyond the coil winding width and are provided at discrete locations on a circumference centered on the rotation axis. A unipolar motor characterized by:

3. 3. The unipolar motor according to claim 2, The coil is wound in a slot formed between adjacent core protrusions. A unipolar motor characterized by:

4. The unipolar motor according to any one of claims 1 to 3, The yoke is provided with a yoke protrusion that is connected to a yoke body that is a portion that overlaps with the permanent magnet and protrudes outward from the yoke body beyond the width of the permanent magnet. A unipolar motor characterized by:

5. 2. The homopolar motor according to claim 1, When the portion of the core around which the coil wire is wound is defined as a core body, and the dimension of the surface of the core body facing the permanent magnet in the direction in which the coil wire runs is defined as a coil winding width, The core has a plurality of core protrusions that protrude outward from the core body beyond the coil winding width and are provided at discrete locations on the circumference of the annular core, the yoke is provided with a yoke protrusion that is connected to a yoke body that is a portion that overlaps with the permanent magnet and that protrudes outward from the yoke body beyond the width of the permanent magnet, the core protrusion and the yoke protrusion have a bent portion bent in a direction perpendicular to the first main surface at at least one end thereof, the core protrusion and the yoke protrusion face each other at the bent portion with a gap in the radial direction therebetween; A unipolar motor characterized by:

6. The unipolar motor according to any one of claims 1 to 5, The core is a split core that can be split into pieces when the coil wire is wound therearound. A unipolar motor characterized by:

7. The unipolar motor according to any one of claims 1 to 6, a gap between the first main surface of the permanent magnet and the coil wire facing the first main surface is provided in a radial direction around the rotation axis; A unipolar motor characterized by:

8. The unipolar motor according to any one of claims 1 to 6, a gap between the first main surface of the permanent magnet and the coil wire facing the first main surface is provided in an axial direction parallel to the rotation axis; A unipolar motor characterized by:

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