Rotary electric machine

Abstract

To increase the efficiency of a rotary electric machine in which a plurality of rotors is arranged so as to sandwich a stator.SOLUTION: A rotary electric machine 1 includes a rotor shaft 3, a stator 20 having a stator core 21, and a pair of rotors 10, 11 connected to the rotor shaft 3 and disposed at a prescribed gap G from the stator core 21. The pair of rotors 10, 11 are opposed to each other so as to sandwich the stator core 21 from both sides in the axial direction. In an opening 24 that is formed to extend through the stator core 21 in the axial direction, a pair of rollers 30, 31 disposed side by side in the axial direction are disposed in a radially rotatable manner. The pair of rollers 30, 31 are in contact with each other in the opening 24, and portions of the rollers projecting outward in the axial direction from the opening 24 are in contact with the pair of rotors 10, 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine, and more particularly to a rotating electric machine in which a plurality of rotors are arranged to sandwich a stator. [Background technology]

[0002] Conventionally, there are known radial gap type rotating electric machines in which a rotor and a stator are arranged with a gap in the radial direction, and axial gap type rotating electric machines in which a rotor and a stator are arranged with a gap in the axial direction. Among these gap type rotating electric machines, there are some in which multiple rotors are arranged so that a stator is sandwiched between them.

[0003] The air gap between the rotor and stator is filled with air, which has a low relative magnetic permeability and high magnetic resistance, so it is considered best to keep the distance between the rotor and stator as small as possible in such a gap-type rotating electric machine. However, if the distance between the rotor and stator is made too small, the rotor may tilt due to vibrations during operation of the rotating electric machine, and the stator may come into contact with each other, which may cause friction, damage, rotation lock, or increased drag loss.

[0004] Therefore, for example, Patent Document 1 discloses a configuration in which, in an axial gap motor in which a stator is disposed between two rotors each fixed to a rotating shaft and aligned in the axial direction, the stator is supported so as to be rotatable relative to each of the rotors by thrust bearings interposed between one of the rotors and the stator, and between the other rotor and the stator.

[0005] According to Patent Document 1, a thrust bearing interposed between the stator and rotor makes it possible to maintain a constant distance between the rotor and stator, thereby suppressing contact between the rotor and stator. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2022-34447 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, "efficiency" in a rotating electric machine is "output / (output + loss)," so to improve the efficiency of a rotating electric machine, it is necessary to increase output while suppressing losses. Here, "output" of a rotating electric machine is "torque x rotation speed," so to increase output, it is necessary to increase the torque (torque density) that can be generated by the same amount of stator coil current and to rotate the rotor smoothly and without waste.

[0008] In this regard, in the device disclosed in Patent Document 1, if the diameter of the rotating body of the bearing interposed between the rotor and stator is reduced in order to narrow the air gap, the rotation speed of each rotating body, which is rotated by the rotor rotating at high speed, becomes too high, which may cause seizure. As such, in the device disclosed in Patent Document 1, there is a certain limit to how small the air gap can be reduced by making the bearing smaller, which makes it difficult to increase the torque density, and ultimately makes it difficult to increase the efficiency of the rotating electric machine.

[0009] Furthermore, according to Patent Document 1, a thrust bearing is said to be able to maintain a constant gap between the rotor and the stator, but it is conceivable that, for example, when the rotating electric machine is in operation, a situation may arise in which one rotor tilts toward the stator while the other rotor tilts away from the stator. In such a situation, the other rotor continues to rotate, but because there is an internal gap in the bearing between the other rotor and the stator, the rotation of each rotating body within the bearing may stop.

[0010] In such a situation, if the tilt of the other rotor is eliminated, the other rotor, which continues to rotate at high speed, will come into contact with the rotating body, which has stopped rotating (via a housing washer, etc.), which may hinder the smooth rotation of the rotating electric machine (reducing the rotation speed) or increase drag losses, which may ultimately lead to a decrease in the efficiency of the rotating electric machine.

[0011] This type of problem can occur not only in axial gap type rotating electric machines such as that in Patent Document 1, but also in radial gap type rotating electric machines, as long as the rotating electric machine has multiple rotors arranged on either side of the stator.

[0012] The present invention has been made in consideration of these points, and its purpose is to provide a technology that can achieve high efficiency in a rotating electric machine in which multiple rotors are arranged on either side of a stator. [Means for solving the problem]

[0013] In order to achieve the above-mentioned objective, in the rotating electric machine of the present invention, a pair of rotating bodies that partially protrude on both sides of the stator core are provided within an opening formed through the stator core, and these protruding portions are brought into contact with the rotor so that the pair of rotating bodies constantly rotates in conjunction with the rotation of the rotor.

[0014] Specifically, the present invention relates to a rotating electric machine comprising a rotating shaft, a stator having an annular stator core coaxial with the rotating shaft, and a pair of rotors each connected to the rotating shaft with a predetermined gap between them and the stator core.

[0015] This rotating electric machine is characterized in that the pair of rotors are arranged axially opposite each other so as to sandwich the stator core from both axial sides of the rotating shaft, or radially opposite each other so as to sandwich the stator core from the radial inside and outside of the rotating shaft, the stator core has an opening formed therein that penetrates in the opposing direction of the pair of rotors, and a pair of rotating bodies are rotatably arranged within the opening so as to be aligned in the opposing direction, the pair of rotating bodies contact each other within the opening, and the portion of each rotating body that protrudes outward in the opposing direction from the opening is configured to contact at least one of the pair of rotors.

[0016] The magnetic field from the stator is generated on both axial sides of the stator in the case of an axial gap type, and on the radial inside and outside of the stator in the case of a radial gap type.However, with this configuration, a pair of rotors are arranged facing each other in the axial or radial direction, sandwiching the stator core, which makes it possible to improve the output torque relative to the size of the rotating electric machine compared to when one rotor is provided for one stator.

[0017] Furthermore, since the pair of rotating bodies arranged within the opening each protrude outward in opposite directions from the opening, even if the specified distance between the rotor and the stator core is narrow, if the rotor tilts due to vibration of the rotating electric machine or the like, it will come into contact with the rotatably arranged rotating body and not with the stator core itself, thereby preventing abrasion, damage, and rotation lock.

[0018] Furthermore, unlike, for example, interposing a bearing between the rotor and stator, simply having a portion of the rotor protrude outward from the opening, in other words, the size of the rotor can be accommodated by the width or thickness of the stator, so even if the diameter of the rotor is increased, the predetermined gap between the rotor and stator core can be made as narrow as possible. This makes it possible to increase torque density by narrowing the predetermined gap between the rotor and stator core as much as possible, while suppressing seizure by increasing the diameter of the rotor.

[0019] Furthermore, the pair of rotating bodies are configured to contact each other within the opening, and the portion of each rotating body that protrudes outward in the opposing direction from the opening is configured to contact at least one of the pair of rotors, thereby achieving the following actions and effects. Below, we will explain two cases: (1) when the pair of rotating bodies and the pair of rotors are configured to contact each other, and (2) when one of the pair of rotating bodies is configured to contact one of the pair of rotors.

[0020] Case (1) In this case, because one rotor and one rotating body are in contact with each other, when one rotor rotates axially relative to the stator core, the one rotating body rotates, for example, clockwise, in the radial direction (or axial direction) at a rotational speed corresponding to the rotational speed of the one rotor (also tentatively referred to as "corresponding rotational speed A"). Similarly, because the other rotor and the other rotating body are in contact with each other, when the other rotor rotates axially relative to the stator core, the other rotating body rotates, for example, counterclockwise, in the radial direction (or axial direction) at a rotational speed corresponding to the rotational speed of the other rotor (also tentatively referred to as "corresponding rotational speed B").

[0021] Thus, the pair of rotating bodies that are in contact with each other within the opening are in an inverted relationship, such that when one rotating body rotates clockwise, the other rotating body rotates counterclockwise, and so do not hinder each other's rotation, allowing the pair of rotors that are in contact with these rotating bodies to rotate smoothly.

[0022] Furthermore, even if corresponding rotation speed A and corresponding rotation speed B are different, in other words, even if there is a speed difference between the rotation speed of one rotor and the rotation speed of the other rotor, the pair of rotating bodies in contact with each other within the opening will rotate (reverse-rotate) at the same rotation speed. As a result, even in a case where, for example, the rotating shafts are configured with two rotating shafts arranged concentrically with each other, and one rotating shaft is connected to one rotor and the other rotating shaft is connected to the other rotor, in other words, even if the pair of rotors are not connected to each other, it is possible to absorb the rotational speed difference (slip) between the pair of rotors via the pair of rotating bodies in contact with each other and reversing rotation.

[0023] Next, we will explain what happens when a rotor tilts and the other rotor separates from the other rotating body, such as when the rotating electric machine is running. Even in this case, the pair of rotors continues to rotate axially relative to the stator core due to electromagnetic force. Furthermore, since one rotor and one rotating body are in contact with each other, one rotating body rotates at the corresponding rotational speed A. Thus, since the pair of rotating bodies are in contact with each other within the opening and are in an inverted relationship, even if the other rotor separates from the other rotating body, the other rotating body continues to rotate at the corresponding rotational speed A.

[0024] Therefore, even if the tilt of the rotors is eliminated and the other rotor comes into contact with the other rotating body, the other rotor rotating at high speed will come into contact with the other rotating body rotating at corresponding rotational speed A, thereby preventing the smooth rotation of the rotating electric machine from being hindered and preventing an increase in drag loss. Note that when the pair of rotors are connected to each other via a rotating shaft or the like, corresponding rotational speed A is ≈ corresponding rotational speed B, so that when the other rotor comes into contact with the other rotating body, it is possible to further prevent the smooth rotation of the rotating electric machine from being hindered and preventing an increase in drag loss.

[0025] Case (2) In this case, it is the same as in case (1) above, where the rotor tilts and the other rotor separates from the other rotating body. Even if the rotor that is not in contact with the rotating body tilts, for example, due to vibrations when the rotating electric machine is running, and comes into contact with the rotating body, the rotating body that is not in contact with the rotor is also constantly rotating, so it is possible to prevent the smooth rotation of the rotating electric machine from being hindered or drag losses from increasing.

[0026] As described above, according to the present invention, not only can the occurrence of abrasion, damage, rotation locking, and seizure be suppressed, but also output torque can be improved, an increase in drag loss can be suppressed, torque density can be increased, and the rotor can rotate smoothly, thereby achieving high efficiency in rotating electric machines.

[0027] Further, in the above-mentioned rotating electric machine, the stator core is annular, the pair of rotors are arranged axially opposite each other so as to sandwich the stator core from both axial sides of the rotating shaft, the opening is formed in the stator core so as to penetrate in the axial direction, the pair of rotating bodies are each rotatable radially and are arranged within the opening so as to be aligned in the axial direction, and the portions of each rotating body protruding outward in both axial directions from the opening may be configured to come into contact with at least one of the pair of rotors.

[0028] According to this configuration, in a so-called axial gap type rotating electrical machine, the efficiency of the rotating electrical machine can be increased in the same manner as described above.

[0029] Furthermore, in the above-mentioned rotating electric machine, the stator core is cylindrical, the pair of rotors are arranged radially opposite each other so as to sandwich the stator core from the radial inside and outside of the rotating shaft, the opening is formed in the stator core so as to penetrate radially, the pair of rotating bodies are each rotatable around the axial direction and are arranged within the opening so as to be aligned radially, and the portions of each rotating body protruding radially inward and outward from the opening may be configured to come into contact with at least one of the pair of rotors.

[0030] According to this configuration, in a so-called radial gap type rotating electrical machine, it is possible to achieve high efficiency of the rotating electrical machine in the same manner as described above.

[0031] In the rotating electric machine, each of the rotating bodies may be made of a magnetic material.

[0032] With this configuration, the rotor and stator are connected via a rotating body made of a magnetic material, which makes it possible to significantly reduce the magnetic resistance between the rotor and stator compared to when the rotor and stator are not in contact with each other via an air gap filled with air having a low relative magnetic permeability. This makes it easier for magnetic flux from the stator to flow to the rotor, thereby increasing torque density and ensuring higher efficiency in the rotating electric machine.

[0033] Furthermore, in the rotating electric machine, an electromagnetic fluid may be interposed between the rotating body and the rotor.

[0034] For example, if the rotor is spherical, the rotor and the rotor will basically be in point contact (unless the rotor's shape is devised), and if the rotor is cylindrical, the rotor and the rotor will basically be in line contact, but with this configuration, the rotor and the rotor can be in surface contact via the electromagnetic fluid. This makes it easier for magnetic flux from the stator to flow to the rotor, further increasing torque density and thereby ensuring even higher efficiency in rotating electrical machines. [Effects of the Invention]

[0035] As described above, according to the rotating electrical machine of the present invention, in a rotating electrical machine in which a plurality of rotors are arranged to sandwich a stator, it is possible to achieve high efficiency of the rotating electrical machine. [Brief explanation of the drawings]

[0036] [Figure 1]1 is a cross-sectional view schematically illustrating a rotating electric machine according to a first embodiment of the present invention, taken along a plane passing through the rotation axis of the rotating electric machine. [Figure 2] 2 is a view taken along line II-II in FIG. 1, schematically illustrating the stator. [Figure 3] 3 is a view taken along the line III-III in FIG. 1, schematically illustrating the rotor. [Figure 4] 10A and 10B are diagrams illustrating a support mode of a pair of rollers. [Figure 5] 3 is a view seen from the radial direction, which schematically illustrates the relationship between the rotor and the rotating body when the rotating electric machine is driven. FIG. [Figure 6] FIG. 10 is a view seen from the radial direction, which schematically illustrates the relationship between the rotor and the rotating body according to the first modification of the first embodiment of the present invention. [Figure 7] 3A and 3B are diagrams for explaining an example of a contact state between a rotor and a rotating body in the first embodiment of the present invention. [Figure 8] 10A and 10B are diagrams illustrating a contact state between a rotor and a rotating body according to a second modification of the first embodiment of the present invention. [Figure 9] 10 is a cross-sectional view taken along a plane passing through the rotation axis of a rotating electric machine, schematically illustrating a rotating electric machine according to a third modification of the first embodiment of the present invention. FIG. [Figure 10] 5 is a cross-sectional view schematically illustrating a rotating electric machine according to a second embodiment of the present invention, taken along a plane passing through the rotation axis of the rotating electric machine. FIG. [Figure 11] FIG. 11 is a view taken along the line XI-XI in FIG. [Figure 12] 1 is a cross-sectional view schematically illustrating a rotating electric machine according to a first reference example, taken along a plane passing through the rotation axis of the rotating electric machine. [Figure 13] 10 is a cross-sectional view schematically showing a rotating electric machine according to a second reference example, taken along a plane passing through the rotation axis of the rotating electric machine. FIG. [Figure 14] 14 is a view taken along line XIV-XIV in FIG. 13, schematically illustrating the stator. [Figure 15] 3 is a view seen from the radial direction, which schematically illustrates the relationship between the rotor and the rotating body when the rotating electric machine is driven. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0038] (Embodiment 1) -Overall configuration of rotating electric machines- FIG. 1 is a cross-sectional view of a rotating electric machine 1 according to this embodiment, taken along a plane passing through a rotation axis RSC of the rotating electric machine 1. FIG. 2 is a schematic view of a stator 20, taken along line II-II in FIG. 1 . FIG. 3 is a schematic view of a rotor 10, taken along line III-III in FIG. 1 . This rotating electric machine 1 is a so-called axial gap rotating electric machine in which rotors 10 and 11 and a stator 20 are spaced apart in the axial direction (the direction along which the rotation axis RSC extends). It is also a permanent magnet synchronous rotating electric machine that is rotationally driven using permanent magnets 17 and 19. The rotating electric machine 1 is used, for example, as an in-wheel motor in a vehicle or a motor for a joint of a robot arm, but can also be used as a generator. As shown in FIG. 1 , the rotating electric machine 1 includes a rotor shaft 3, a stator 20, and a pair of rotors 10 and 11.

[0039] -Rotor shaft- The rotor shaft (rotating shaft) 3 is made of a metal such as iron and is formed into a cylindrical shape as shown in Figures 2 and 3. As shown in Figure 1, the rotor shaft 3 is rotatably supported by a motor housing (not shown) or the like via bearings 5.

[0040] - Stator - <Overall configuration of the stator> 1, the stator 20 includes a stator core 21, a stator coil 27, and a pair of rollers 30, 31. As shown in FIG. 2, the stator core 21 has twelve core body portions 23 and twelve coil mounting portions 25.

[0041] Each core body 23 is formed in the shape of a trapezoidal column extending in the axial direction. An opening 24 having a rectangular cross section and penetrating in the axial direction is formed in each core body 23. In each core body 23, a portion defining the radially outer side of the opening 24 is formed with two conical outer support portions 24a aligned in the axial direction, the diameter of which decreases radially inward, as shown in FIGS. 1 and 2 . In addition, in each core body 23, a portion defining the radially inner side of the opening 24 is formed with two conical inner support portions 24b aligned in the axial direction, the diameter of which decreases radially outward.

[0042] Each coil mounting portion 25 has a trapezoidal cylindrical frame portion 25a extending in the axial direction, and flange portions 25b protruding outward from both axial ends of the frame portion 25a so as to form a trapezoidal frame shape when viewed in the axial direction. As shown in Figures 1 and 2, in each coil mounting portion 25, the core body 23 is fitted into the inner space of the frame portion 25a, and the stator coil 27 is wound around the area defined by the frame portion 25a and both flange portions 25b.

[0043] 2, the stator core 21 is formed in an annular shape by connecting the oblique sides of trapezoidal frame-shaped flange portions 25b of twelve coil mounting portions 25, each of which has a core body portion 23 fitted therein and a stator coil 27 wound therearound, in the circumferential direction, as shown in FIG. 2. More precisely, the stator core 21 is formed in an annular shape with an outer circumferential shape that is a regular dodecagon and an inner circumferential shape that is also a regular dodecagon.

[0044] <Pair of rollers> FIG. 4 is a diagram illustrating a support mode for a pair of rollers 30, 31. A pair of rollers (rotating bodies) 30, 31 are rotatably provided within each opening 24, aligned in the axial direction. Each roller 30, 31 is formed of a magnetic material. The magnetic material is not particularly limited as long as it can be magnetized, and examples thereof include ferromagnetic materials such as iron, nickel, cobalt, and gadolinium. The roller 30 is formed in a cylindrical shape and, as shown in FIG. 4(a), has recesses 32 at both axial ends. The roller 31 paired with the roller 30 is formed in the same shape and size as the roller 30, i.e., cylindrical, and has recesses 33 at both axial ends.

[0045] As shown in FIG. 4(a), the rollers 30, 31 are attached to the core body 23 by fitting the tops of the outer and inner support portions 24a, 24b into the recesses 32, 33, respectively. This allows each roller 30, 31 to rotate within the opening 24 in a direction connecting the top of the outer support portion 24a and the top of the inner support portion 24b, i.e., around the radial direction of the stator core 21 (see the axis RRA in FIGS. 1 and 2). The pair of rollers 30, 31 are in contact with each other within the opening 24. This causes the pair of rollers 30, 31 to rotate in an opposite direction, such that when the roller 30 rotates in the radial direction, for example, clockwise, the roller 31 rotates in the radial direction counterclockwise (see FIG. 5).

[0046] The diameter of roller 30 is set so that roller 30 comes into contact with roller 31 in opening 24 and protrudes from opening 24 axially outward (left side in FIG. 4(a)) by length G. Similarly, the diameter of roller 31 is set so that roller 31 comes into contact with roller 30 in opening 24 and protrudes from opening 24 axially outward (right side in FIG. 4(a)) by length G. In other words, the diameter of each of rollers 30, 31 is set to be equal to the sum of half the axial length of core body 23 (= thickness of stator core 21) and the protrusion length G.

[0047] The support form of the pair of rollers 30, 31 is not limited to the form shown in Fig. 4(a) and may be, for example, the form shown in Fig. 4(b). Specifically, as shown in Fig. 4(b), shafts 34, 35 may be provided at both axial ends of the cylindrical rollers 30, 31, and these shafts 34, 35 may be inserted into recesses 24c formed in a portion that defines the radially outer and inner sides of the opening 24, thereby supporting the pair of rollers 30, 31 so as to be rotatable around the radial direction.

[0048] The stator 20 configured as described above is fixed to a motor housing or the like so that the axis of the annular stator core 21 is coaxial with the axis of the rotor shaft 3. In the stator 20 arranged in this manner, when a three-phase AC current is applied to the stator coil 27, a rotating magnetic field is generated to rotate the rotors 10 and 11.

[0049] -Rotor- Rotor 10 is made of a magnetic metal (for example, iron) and includes a rotor core 13 and a permanent magnet 17, as shown in Figures 1 and 3. Rotor 11 is also made of a magnetic metal and includes a rotor core 15 and a permanent magnet 19, as shown in Figure 1. Since rotors 10 and 11 have the same structure, rotor 10 will be described below as a representative.

[0050] 1 and 3, rotor core 13 is formed in an annular shape with approximately the same size as stator core 21, and its inner peripheral edge is connected (fixed) to the outer periphery of rotor shaft 3 by, for example, shrink fitting or welding. Twelve permanent magnets 17 are attached to rotor core 13.

[0051] As shown in Fig. 3, the permanent magnet 17 is formed in a trapezoidal plate shape. The type of the permanent magnets 17, 19 is not particularly limited, and examples thereof include ferrite magnets, neodymium magnets, samarium-cobalt magnets, and alnico magnets. The twelve permanent magnets 17 are arranged in an annular shape on the rotor core 13 with N poles (see the hatched area in Fig. 3) and S poles alternately arranged and spaced apart in the circumferential direction so that the upper bases of the trapezoids face radially inward. The radial positions of the permanent magnets 17 on the rotor core 13 correspond to the radial positions of the rollers 30 on the stator core 21.

[0052] 1, the pair of rotors 10, 11 configured in this manner are connected to the rotor shaft 3, facing each other in the axial direction and sandwiching the stator core 21 from both axial sides. More specifically, the rotor 10 is arranged so that the permanent magnets 17 attached to the rotor core 13 come into contact with the portions of the rollers 30 that protrude axially outward from the openings 24. The rotor 11 is arranged so that the permanent magnets 19 attached to the rotor core 15 come into contact with the portions of the rollers 31 that protrude axially outward from the openings 24. In other words, the pair of rotors 10, 11 are arranged so that the clearance between the permanent magnets 17, 19 and the rollers 30, 31 is zero when the rotating electric machine 1 is in a non-driving state.

[0053] As described above, the rollers 30, 31 protrude from the opening 24 by a protrusion length G, and therefore the pair of rotors 10, 11 face each other on both axial sides of the stator core 21, and are disposed with a predetermined gap G between them and the stator core 21. The pair of rotors 10, 11 are disposed such that, for example, the N and S poles of the permanent magnet 17 and the N and S poles of the permanent magnet 19 that faces it in the axial direction are opposite to each other in the circumferential direction.

[0054] By arranging the pair of rotors 10, 11 in this manner, the magnetic field from the stator 20 and the repulsion and attraction between the permanent magnets 17, 19 cause the pair of rotors 10, 11 to rotate in the same direction around the axial direction relative to the stator 20, thereby rotating the rotor shaft 3. Here, while the magnetic field from the stator 20 is generated on both axial sides of the stator 20 in an axial gap type, in this embodiment, the pair of rotors 10, 11 are provided so as to sandwich the stator core 21 in the axial direction, making it possible to improve the output torque relative to the size of the rotating electric machine 1 compared to when one rotor is provided for one stator.

[0055] -Actions and Effects- Next, the operation and effect of the rotating electric machine 1 configured as above will be explained. However, in order to facilitate understanding of the present invention, a rotating electric machine according to a reference example will be explained first.

[0056] <Rotating Electric Machine of Reference Example 1> 12 is a cross-sectional view schematically illustrating a rotating electric machine 101 according to Reference Example 1, taken along a plane passing through a rotation axis RSC of the rotating electric machine 101. As shown in FIG. 12, the rotating electric machine 101 according to Reference Example 1 is similar to the rotating electric machine 1 of this embodiment in that it includes a rotor shaft 103 rotatably supported by a motor housing or the like via a bearing 105, a stator 120 in which a stator coil 127 is wound around a stator core 121, and a pair of rotors 110 in which a permanent magnet 117 is attached to a rotor core 113 and which are disposed to sandwich the stator core 121. However, unlike the rotating electric machine 1 of this embodiment, the rotating electric machine 101 according to Reference Example 1 does not include a pair of rollers 30, 31 on the stator 120, and the rotor 110 and the stator 120 are disposed with an axial gap G3 between them via an air gap AG.

[0057] Here, the air gap AG between the rotor 110 and the stator 120, which is filled with air with a low relative magnetic permeability, has a high magnetic resistance, and therefore it is considered desirable to make the gap G3 between the rotor 110 and the stator 120 as narrow as possible. However, it is known that if the diameter of the rotor 110 is increased, the rotor 110 may tilt as shown by the white dashed arrow in Fig. 12 due to vibrations during operation of the rotating electric machine 101 or, in the case of an in-wheel motor, lateral forces acting on the tire.

[0058] Therefore, in the rotating electric machine 101 of Reference Example 1, if the gap G3 between the rotor 110 and the stator 120 is made extremely narrow, the rotor 110, which has been tilted due to vibrations or the like when the rotating electric machine 101 is in operation, may come into contact with the stator 120 (stator core 121), which may result in abrasion, damage, or rotation lock.

[0059] On the other hand, if the distance G3 between the rotor 110 and the stator 120 is widened in the rotating electric machine 101 according to Reference Example 1 in order to avoid contact between the tilted rotor 110 and the stator 120, it is expected that the presence of a large air gap AG will make it difficult to increase the torque density, and ultimately make it difficult to increase the efficiency of the rotating electric machine 101.

[0060] <Rotating electric machine of Reference Example 2> Fig. 13 is a cross-sectional view taken along a plane passing through a rotation axis RSC of the rotating electric machine 201, which is a schematic illustration of a rotating electric machine 201 according to Reference Example 2. Fig. 14 is a view taken along line XIV-XIV in Fig. 13, which is a schematic illustration of a stator 220. Fig. 15 is a view seen from the radial direction, which is a schematic illustration of the relationship between a rotor 210 and rollers 230 when the rotating electric machine 201 is in operation. As shown in Fig. 13, the rotating electric machine 201 according to Reference Example 2 is similar to the rotating electric machine 1 of this embodiment in that it includes a rotor shaft 203 rotatably supported by a motor housing or the like via bearings 205, a stator 220 in which a stator coil 227 is wound around a stator core 221, and a pair of rotors 210, 211 in which a permanent magnet 217 is attached to a rotor core 213 and which are disposed so as to sandwich the stator core 221.

[0061] 13 and 14, the rotating electric machine 201 according to Reference Example 2 differs from the rotating electric machine 101 according to Reference Example 1 in that a pair of rollers 230, 231 are provided on the stator core 221 so as to be rotatable around the radial direction, and the pair of rollers 230, 231 are in contact with the pair of rotors 210, 211, similarly to the rotating electric machine 1 according to this embodiment. However, the rotating electric machine 201 according to Reference Example 2 does not have an opening that penetrates the stator core 221 in the axial direction, and therefore differs from the rotating electric machine 1 according to this embodiment in that the pair of rollers 230, 231 are not in contact with each other.

[0062] In the rotating electric machine 201 configured in this manner, when the rotor 210 rotates as shown by the solid black arrow in Fig. 15 during operation, the rollers 230 in contact with the rotor 210 (more precisely, the permanent magnets 217) rotate as shown by the hollow arrow in Fig. 15. Therefore, unlike the rotating electric machine 101 according to Reference Example 1, even if the rotor 210 tilts due to vibrations or the like during operation of the rotating electric machine 201, the rotor 210 hits the rotatably provided rollers 230, and therefore the rotor 210 and the stator core 221 do not come into contact with each other, and there is no risk of abrasion, damage, or rotation lock.

[0063] However, because there is a large difference between the radius of the rotors 210, 211 (more precisely, the distance R1 from the rotation center of the rotors 210, 211 to the center of the rollers 230, 231) and the radius R2 of the rollers 230, 231, the rollers 230, 231 rotate at a rotational speed that is (R1 / R2) times faster than the high-speed rotating rotors 210, 211. For this reason, the shorter the protrusion length G4 of the rollers 230, 231 (the distance between the rotors 210, 211 and the stator core 221), the faster the rollers 230, 231 rotate, making them more susceptible to seizure. As described above, in the rotating electric machine 201 according to Reference Example 2, there is a certain limit to how much the radius R2 of the rollers 230, 231 can be reduced to narrow the gap G4 between the rotors 210, 211 and the stator core 221. Therefore, it is difficult to increase the torque density, and ultimately, it is difficult to increase the efficiency of the rotating electric machine 201.

[0064] Furthermore, in the rotating electric machine 201 according to Reference Example 2, if the rotors 210, 211 tilt due to vibrations or the like while the rotating electric machine 201 is in operation, it is possible that, for example, one of the rotors 210 may separate from one of the rollers 230. In such a situation, the pair of rotors 210, 211 and the other roller 231 continue to rotate, but the rotation of one of the rollers 230 may stop.

[0065] In such a situation, if the tilt of the rotor 210 is eliminated, the rotor 210, which is rotating at high speed, will come into contact with the roller 230, which has stopped rotating, which may hinder the smooth rotation of the rotating electric machine 201 (reduced rotation speed) or increase drag loss, which may ultimately lead to a decrease in the efficiency of the rotating electric machine 201.

[0066] These problems in the rotating electric machine 201 according to the second reference example can also occur in a structure in which a thrust bearing is interposed between the rotors 210 and 211 and the stator core 221.

[0067] <Rotating Electric Machine of This Embodiment> Therefore, in the rotating electric machine 1 according to this embodiment, as described above, a pair of rollers 30, 31 are provided in the opening 24 formed through the stator core 21, protruding partially on both sides of the stator core 21, and these pair of rollers 30, 31 are constantly rotated in conjunction with the rotation of the rotors 10, 11.

[0068] First, since the pair of rollers 30, 31 provided within the opening 24 each protrude axially outward from the opening 24, even if the predetermined gap G between the rotors 10, 11 and the stator core 21 is narrowed, the rotors 10, 11 tilted due to vibration of the rotating electric machine 1 or the like will come into contact with the rotatably provided rollers 30, 31, but will not come into contact with the stator core 21 itself, thereby preventing abrasion, damage, or rotation lock.

[0069] Furthermore, unlike, for example, interposing bearings or the like between the rotors 10, 11 and the stator 20, only a portion of each roller 30, 31 protrudes axially outward from the opening 24. In other words, the size of the rollers 30, 31 can be accommodated by the width or thickness of the stator core 21, so that even if the diameter of the rollers 30, 31 is increased, the predetermined gap G between the rotors 10, 11 and the stator core 21 can be made as narrow as possible. This makes it possible to increase torque density by making the predetermined gap G between the rotors 10, 11 and the stator core 21 as narrow as possible, while suppressing seizure by increasing the diameter of the rollers 30, 31.

[0070] FIG. 5 is a diagram, viewed from the radial direction, that schematically illustrates the relationship between the rotors 10, 11 and the rollers 30, 31 when the rotating electric machine 1 is driven. In the rotating electric machine 1 of this embodiment, the rotor 10 (more precisely, the permanent magnet 17) and the roller 30 are in contact with each other. Therefore, when the rotor 10 rotates axially relative to the stator core 21 as indicated by the solid arrow in FIG. 5(a), the roller 30 rotates radially and clockwise in FIG. 5(a) at a rotational speed corresponding to the rotational speed of the rotor 10 (hereinafter also referred to as a "first corresponding rotational speed") as indicated by the hollow arrow in FIG. 5(a). Note that the first corresponding rotational speed is, for example, (X1 / Y1) times the rotational speed of the rotor 10, where X1 is the distance from the center of rotation of the rotors 10, 11 to the center of the rollers 30, 31, and Y1 is the radius of the rollers 30, 31.

[0071] Similarly, since the rotor 11 and the roller 31 are in contact with each other, when the rotor 11 rotates axially relative to the stator core 21, as shown by the hatched arrow in Figure 5(a), the roller 31 rotates radially and counterclockwise in Figure 5(a) at a first corresponding rotational speed, as shown by the dotted arrow in Figure 5(a).

[0072] As a result, the pair of rollers 30, 31 that are in contact with each other within the opening 24 are in an inverted relationship as described above, and therefore do not hinder each other's rotation, allowing the pair of rotors 10, 11 that are in contact with these rollers 30, 31 to rotate smoothly.

[0073] Next, we will explain a case where the rotors 10, 11 tilt during operation of the rotating electric machine 1, causing the rotor 11 to separate from the roller 31, as shown in FIG. 5(b). Even in this case, the pair of rotors 10, 11 continues to rotate axially relative to the stator core 21, as indicated by the solid and hatched arrows in FIG. 5(b), because they are driven solely by the magnetic field from the stator 20 and the repulsion and attraction between the permanent magnets 17, 19. Furthermore, because the rotor 10 and the roller 30 are in contact with each other, the roller 30 rotates at a first corresponding rotational speed, as indicated by the hollow arrow in FIG. 5(b). Thus, the pair of rollers 30, 31 are in contact with each other within the opening 24, and the rollers 30, 31 are in a reversing relationship. Therefore, even if the rotor 11 separates from the roller 31, the roller 31 continues to rotate at the first corresponding rotational speed, as indicated by the dotted arrow in FIG. 5(b).

[0074] Therefore, even if the inclination of the rotor 11 is eliminated and the rotor 11 comes into contact with the roller 31, the rotor 11 rotating at high speed will come into contact with the roller 31 rotating at the first corresponding rotation speed, thereby preventing the smooth rotation of the rotating motor 1 from being hindered and preventing an increase in drag loss.

[0075] As described above, according to this embodiment, not only can the occurrence of abrasion, damage, rotation locking, and seizure be suppressed, but also output torque can be improved, an increase in drag loss can be suppressed, torque density can be increased, and smooth rotation of rotors 10 and 11 can be achieved, thereby achieving high efficiency of the rotating electric machine 1.

[0076] Moreover, because the rotors 10, 11 and the stator 20 are connected via the rollers 30, 31 made of a magnetic material, it is possible to significantly reduce the magnetic resistance between the rotors 10, 11 and the stator 20 compared to a case where the rotor 110 and the stator 120 are not in contact with each other via an air gap AG filled with air having a low relative magnetic permeability, as in the rotating electric machine 101 according to Reference Example 1. Therefore, the magnetic flux from the stator 20 flows more easily toward the rotors 10, 11, which makes it possible to further increase the torque density, thereby more reliably achieving high efficiency for the rotating electric machine 1.

[0077] (Variation 1) This modified example differs from the first embodiment in that a pair of rotors is arranged so that the clearance between only one rotor and one roller is 0 when the rotating electric machine is in a non-driving state. The following will mainly explain the differences from the first embodiment.

[0078] Figure 6 is a diagram viewed from the radial direction that schematically illustrates the relationship between the rotors 10, 11 and the rollers 30, 31 according to this modification. Figure 6(a) shows the case where the rotors 10, 11 are not tilted, or where a force acts on the rotors 10, 11 in the direction of the dashed arrow, and Figure 6(b) shows the case where a force acts on the rotors 10, 11 in the direction of the thick arrow.

[0079] In the rotating electric machine 1 according to this modification, similarly to the first embodiment, the rotor 10 is connected to the rotor shaft 3 so that the permanent magnets 17 attached to the rotor core 13 come into contact with the rollers 30. In contrast, unlike the first embodiment, the rotor 11 is connected to the rotor shaft 3 so that the permanent magnets 19 attached to the rotor core 15 are spaced a predetermined distance G1 from the rollers 31, as shown in FIG. 6(a).

[0080] In the rotating electric machine 1 according to this modified example configured as described above, when the rotors 10, 11 are not tilted or when a force acts on the rotors 10, 11 in the direction of the dashed arrows, as shown in Fig. 6(a), the state is the same as the state shown in Fig. 5. That is, the pair of rotors 10, 11 continue to rotate axially relative to the stator core 21, as indicated by the solid arrow and the hatched arrow in Fig. 6(a). Furthermore, when the roller 30 rotates at the first corresponding rotational speed, as indicated by the hollow arrow in Fig. 6(a), the roller 31 also continues to rotate at the first corresponding rotational speed, as indicated by the dotted arrow in Fig. 6(a).

[0081] Therefore, even if the rotor 11 that is not in contact with the roller 31 is tilted, for example, due to vibration of the rotating electric machine 1, as shown in Figure 6(b), and comes into contact with the roller 31 while rotating at high speed, the roller 31 that was not in contact with the rotor 11 is also always rotating at the first corresponding rotational speed, so that the smooth rotation of the rotating electric machine 1 is not hindered and drag loss is not increased.

[0082] 6(b), rotor 10 separates from roller 30, but rotor 11 comes into contact with roller 31. In this case, the pair of rotors 10, 11 continue to rotate axially relative to stator core 21, as indicated by the solid black arrows and hatched arrows in FIG. 6(b). Furthermore, because rotor 11 and roller 31 are in contact, roller 31 rotates, as indicated by the dotted arrow in FIG. 6(b). Thus, because the pair of rollers 30, 31 are in an opposing rotational relationship, even when rotor 10 separates from roller 30, roller 30 continues to rotate, as indicated by the hollow arrow in FIG. 6(b).

[0083] Therefore, the tilt of the rotors 10, 11 is eliminated, and even if the rotor 10 and the roller 30 come into contact, the rotor 10 rotating at high speed will come into contact with the roller 30 rotating at the first corresponding rotational speed, thereby preventing the smooth rotation of the rotating motor 1 from being hindered and preventing an increase in drag loss.

[0084] (Variation 2) This modification differs from the first embodiment in that an electromagnetic fluid is interposed between the rotor and the roller. The following will mainly explain the differences from the first embodiment.

[0085] FIG. 7 is a diagram illustrating an example of contact between the rotor 10 and the rotating bodies 36 and 30 in the first embodiment, and FIG. 8 is a diagram illustrating a contact between the rotor 10 and the roller 30 in this modified example. In the first embodiment, when a ball 36 is used as the "rotating body rotatably provided in the opening," the rotor 10 (more precisely, the permanent magnet 17) and the ball 36 are in point contact, as indicated by reference symbol P in FIG. 7(a). Even when the rotor 10 is shaped in a way that the ball 36 is used as the rotating body and the permanent magnet 17 has a groove 17a with an arc-shaped bottom, as shown in FIG. 7(b), the rotor 10 and the ball 36 are only in line contact, as indicated by reference symbol L1 in FIG. 7(b). Furthermore, in the first embodiment, when a roller 30 is used as the rotating body, the rotor 10 and the roller 30 are only in line contact, as indicated by reference symbol L2 in FIG. 7(c).

[0086] Therefore, in this modification, to facilitate the flow of magnetic flux from the stator 20 toward the rotors 10 and 11, an electromagnetic fluid 40 is interposed between the rollers 30 and the rotor 10, as shown in FIG. 8(a). Here, "electromagnetic fluid" refers to a magnetic fluid in which magnetic powder particles, such as iron powder, are mixed in oil and stably dispersed using a surfactant. When a few drops of such electromagnetic fluid 40 are dropped between the rollers 30 and 31 and the rotors 10 and 11, the electromagnetic fluid 40 remains between the rollers 30 and 31 and the rotors 10 and 11 due to the influence of the permanent magnets 17 and 19. As a result, the rollers 30 and 31 and the rotors 10 and 11 come into surface contact with each other through the electromagnetic fluid 40, as shown in FIG. 8(b).

[0087] As described above, according to this modified example, the rollers 30, 31 and the rotors 10, 11 are brought into surface contact with each other via the electromagnetic fluid 40, which makes it easier for the magnetic flux from the stator 20 to flow toward the rotors 10, 11, thereby further increasing the torque density, thereby more reliably achieving high efficiency for the rotating electric machine 1.

[0088] (Variation 3) This modification differs from the first embodiment in that it includes a plurality of stators. The following description will focus on the differences from the first embodiment.

[0089] 9 is a cross-sectional view schematically illustrating a rotating electric machine 1A according to this modification, taken along a plane passing through the rotation axis RSC of the rotating electric machine 1A. As shown in FIG. 9, the rotating electric machine 1A includes a rotor shaft 3, two stators 20, 20A, and three rotors 10, 11, 50. The stator 20A has the same structure as the stator 20, including the fact that the rollers 30A, 31A are the same as the rollers 30, 31. The two stators 20, 20A are fixed to a motor housing or the like so as to face each other in the axial direction.

[0090] 9, the rotor 50 includes a rotor core 51 and permanent magnets 53. The rotor core 51 is made of resin and is formed in an annular shape with the same size as the rotor cores 13, 15, and its inner peripheral edge is connected to the outer periphery of the metallic rotor shaft 3 by an appropriate method, for example, using insert molding or bolts. Twelve permanent magnets 53 equivalent to the permanent magnets 17, 19 are embedded in the rotor core 51 at the same radial positions as the permanent magnets 17, 19.

[0091] As shown in FIG. 9 , the three rotors 10, 11, and 50 are connected to the rotor shaft 3 and axially opposed to each other, sandwiching the two stators 20 and 20A. More specifically, the rotor 10 is disposed so that the permanent magnets 17 attached to the rotor core 13 are in contact with the rollers 30 of the stator 20. The rotor 50 is disposed so that the rotor-10-side surface of the permanent magnets 53 embedded in the rotor core 51 is in contact with the rollers 31 of the stator 20, and the rotor 11-side surface of the permanent magnets 53 is in contact with the rollers 30A of the stator 20A. The rotor 11 is disposed so that the permanent magnets 19 attached to the rotor core 15 are in contact with the rollers 31A of the stator 20A. In this manner, in the rotating electric machine 1A according to this modification, the pair of rotors 10 and 50 are disposed axially opposed to each other, sandwiching the stator 20, and the pair of rotors 50 and 11 are disposed axially opposed to each other, sandwiching the stator 20A.

[0092] According to this modified example, by utilizing the rotating magnetic fields from the two stators 20, 20A and adopting a rotor 50 having a resin rotor core 51 as one of the three rotors 10, 11, 50, the weight per unit length of the moving side (rotor shaft 3 and the three rotors 10, 11, 50) can be reduced compared to a configuration in which all rotor cores are made of metal, thereby achieving further efficiency improvements in the rotating electric machine 1A.

[0093] Of the three rotors 10, 11, 50, rotor cores 13, 15 of rotors 10, 11 located at both axial ends must be made of a magnetic metal to function as a back yoke, which causes magnetic flux from stators 20, 20A to pass through rotor cores 13, 15, then move (flow) it circumferentially and channel it through a path different from the path it came in through. In contrast, rotor core 51 of rotor 50 located in the middle may be made of resin, as it is only necessary to allow magnetic flux from stators 20, 20A to pass through rotor core 51 itself.

[0094] Therefore, if the rotor cores of the rotors located at both axial ends of the multiple rotors are made of magnetic metal, the rotating electric machine may include (n+1) rotors facing each other in the axial direction, sandwiching n (an integer greater than or equal to 3) stators, and the rotor cores of the (n-1) rotors other than those at both axial ends may be made of resin.

[0095] (Embodiment 2) This embodiment differs from the first embodiment in that the present invention is applied to a so-called radial gap type rotating electrical machine. The following description will focus on the differences from the first embodiment.

[0096] -Overall configuration of rotating electric machines- Fig. 10 is a cross-sectional view of a rotating electric machine 61 according to this embodiment, taken along a plane passing through the rotational axis RSC of the rotating electric machine 61, and Fig. 11 is a view taken along the arrows XI-XI in Fig. 10. As shown in Fig. 10, the rotating electric machine 61 is a so-called radial gap type rotating electric machine in which rotors 70, 71 and a stator 80 are arranged with a gap therebetween in the radial direction (a direction perpendicular to the rotational axis RSC), and is also a permanent magnet synchronous rotating electric machine that is rotationally driven using permanent magnets (not shown). The rotating electric machine 61 includes two rotor shafts 63, 64, a stator 80, and inner and outer rotors 70, 71.

[0097] -Rotor shaft- The rotor shafts (rotating shafts) 63, 64 are made of a metal such as iron, and as shown in Figures 10 and 11, are each formed in a cylindrical shape, and are rotatably supported on a motor housing or the like via bearings 5 ​​so that the axis of rotor shaft 63 and the axis of rotor shaft 64 are coaxial.

[0098] - Stator - 10 and 11, the stator 80 includes a stator core 81, a stator coil 87, and inner and outer rollers 90, 91. The stator core 81 is formed in a cylindrical shape extending in the axial direction, and is wound with the stator coil 87. The stator 80 is fixed to a motor housing or the like so that the axis of the cylindrical stator core 81 and the axis of the rotor shafts 63, 64 are coaxial.

[0099] 10 and 11, stator core 81 is formed with 12 radially penetrating openings 84 at equal intervals in the circumferential direction. A pair of inner and outer rollers (rotating bodies) 90, 91 is provided in each opening 84 so as to be aligned in the radial direction.

[0100] Two conically recessed recesses 84a that decrease in diameter toward one axial side are formed side by side in the radial direction in a portion of stator core 81 that defines one axial side (the left side in FIG. 10) of opening 84. Furthermore, two conically recessed recesses 84b that decrease in diameter toward the other axial side are formed side by side in the radial direction in a portion of stator core 81 that defines the other axial side (the right side in FIG. 10).

[0101] The inner and outer rollers 90, 91 are each made of a magnetic material. The inner roller 90 is formed in a cylindrical shape, with both axial end portions 90a formed in a conical shape that tapers in diameter as it extends axially outward. The outer roller 91, which forms a pair with the inner roller 90, has the same shape and size as the inner roller 90, i.e., is formed in a cylindrical shape, with both axial end portions 91a formed in a conical shape that tapers in diameter as it extends axially outward.

[0102] 10, the inner and outer rollers 90, 91 configured in this manner are attached to the stator core 81 by fitting their axially opposite end portions 90a, 91a into recesses 84a, 84b, and are rotatable around the axial direction within the opening 84. The inner and outer rollers 90, 91 are in contact with each other within the opening 84. As a result, the inner and outer rollers 90, 91 have an opposing relationship, such that when the inner roller 90 rotates clockwise around the axial direction, the outer roller 91 rotates counterclockwise around the axial direction (see the hollow arrows and dotted arrows in FIG. 11).

[0103] The diameter of the inner roller 90 is set so that the inner roller 90 comes into contact with the outer roller 91 inside the opening 84 and protrudes a length G2 radially inward from the opening 84. Similarly, the diameter of the outer roller 91 is set so that the outer roller 91 comes into contact with the inner roller 90 inside the opening 84 and protrudes a length G2 radially outward from the opening 84. In other words, the diameters of the inner and outer rollers 90, 91 are set to be equal to the sum of half the thickness of the stator core 81 and the protrusion length G2.

[0104] -Rotor- The inner rotor 70 is made of a magnetic metal (for example, iron) and is formed in a cylindrical shape. A permanent magnet (not shown) is embedded in the inner rotor 70. The inner peripheral edge of the inner rotor 70 is connected (fixed) to the outer peripheral part of the rotor shaft 63 by, for example, shrink fitting.

[0105] The outer rotor 71 is made of a magnetic metal (for example, iron) and, as shown in Fig. 10, is formed into a bottomed cylindrical shape and includes a cylindrical rotor core 73 and a disk-shaped end plate 75 attached to the other axial end of the rotor core 73. A permanent magnet (not shown) is embedded in the rotor core 73. The outer rotor 71 is fixed to the rotor shaft 64 by connecting the center of the disk-shaped end plate 75 to the end of the rotor shaft 64, for example, by welding.

[0106] The inner and outer rotors 70, 71 configured in this manner are arranged radially opposite each other so as to sandwich the stator core 81 from the radially inner and outer sides, as shown in Figures 10 and 11. More specifically, the inner rotor 70 is arranged so that its outer peripheral surface comes into contact with the portion of the inner roller 90 that protrudes radially inward from the opening 84. The outer rotor 71 is arranged so that the inner peripheral surface of the rotor core 73 comes into contact with the portion of the outer roller 91 that protrudes radially outward from the opening 84. In other words, the inner and outer rotors 70, 71 are arranged so that the clearance between them and the inner and outer rollers 90, 91 is zero when the rotating electric machine 61 is in a non-driving state.

[0107] As described above, the protruding length of the inner and outer rollers 90, 91 from the opening 84 is G2, and therefore the inner and outer rotors 70, 71 face each other from the radial inside and outside so as to sandwich the stator core 81, and are provided with a predetermined gap G2 between them. By providing the inner and outer rotors 70, 71 in this manner, the inner and outer rotors 70, 71 rotate in the same direction around the axial direction relative to the stator 80 due to the repulsion and attraction between the magnetic field from the stator 80 and the permanent magnets, thereby rotating the rotor shafts 63, 64. Here, while the magnetic field from the stator 80 is generated on the radial inside and outside of the stator 80 in a radial gap type, in this embodiment, the inner and outer rotors 70, 71 are provided so as to sandwich the stator core 81 in the radial direction. Therefore, the output torque relative to the size of the rotating electric machine 61 can be improved compared to when one rotor is provided for one stator.

[0108] -Actions and Effects- First, the inner and outer rollers 90, 91 provided within the opening 84 protrude radially inward and outward from the opening 84, respectively. Therefore, even if the predetermined gap G2 between the inner and outer rotors 70, 71 and the stator core 81 is narrowed, the inner and outer rotors 70, 71 that are tilted due to vibration of the rotating electric machine 61 or the like will come into contact with the rotatably provided inner and outer rollers 90, 91, but will not come into contact with the stator core 81 itself, thereby preventing abrasion, damage, or rotation lock.

[0109] Moreover, because only portions of the inner and outer rollers 90, 91 protrude radially inward and outward from the openings 84, in other words, the size of the inner and outer rollers 90, 91 can be accommodated by the thickness of the stator core 81, etc., so even if the diameters of the inner and outer rollers 90, 91 are increased, the predetermined gap G2 between the inner and outer rotors 70, 71 and the stator core 81 can be made as narrow as possible. This makes it possible to increase torque density by making the predetermined gap G2 between the inner and outer rotors 70, 71 and the stator core 81 as narrow as possible, while suppressing seizure by increasing the diameters of the inner and outer rollers 90, 91.

[0110] In the rotating electric machine 61 of this embodiment, the inner rotor 70 and the inner roller 90 are in contact with each other, and therefore when the inner rotor 70 rotates in the axial direction relative to the stator core 81 as shown by the filled arrow in Fig. 11, the inner roller 90 rotates in the axial direction and in the clockwise direction in Fig. 11 at a rotational speed corresponding to the rotational speed of the inner rotor 70 (hereinafter also referred to as "second corresponding rotational speed") as shown by the hollow arrow in Fig. 11. Note that the second corresponding rotational speed is (X2 / Y2) times the rotational speed of the inner rotor 70 when the radius of the inner rotor 70 is X2 and the radius of the inner roller 90 is Y2.

[0111] Similarly, because the outer rotor 71 and the outer roller 91 are in contact with each other, when the outer rotor 71 rotates axially relative to the stator core 81 as shown by the hatched arrow in Fig. 11, the outer roller 91 rotates axially and counterclockwise in Fig. 11 at a rotational speed corresponding to the rotational speed of the outer rotor 71 (hereinafter also referred to as the "third corresponding rotational speed") as shown by the dotted arrow in Fig. 11. Note that the third corresponding rotational speed is (X3 / Y3) times the rotational speed of the outer rotor 71 when the radius of the inner space of the outer rotor 71 is X3 and the radius of the outer roller 91 is Y3.

[0112] Here, since Y2 = Y3 and X3 > X2, the third corresponding rotational speed > the second corresponding rotational speed. However, since the inner and outer rollers 90, 91 that are in contact with each other within the opening 84 are in a counter-rotating relationship as described above, they rotate at the same rotational speed (lower than the third corresponding rotational speed and higher than the second corresponding rotational speed). As a result, in the rotating electric machine 61 according to this embodiment, it is possible to absorb the difference in rotational speed (slip) between the inner rotor 70 and the outer rotor 71 via the inner and outer rollers 90, 91 that are in contact with each other and counter-rotating.

[0113] Furthermore, even if the outer rotor 71 and the outer roller 91 separate, or the inner rotor 70 and the inner roller 90 separate, the inner and outer rollers 90, 91 continue to rotate. Therefore, even if the inner rotor 70 and the inner roller 90 come into contact again, or the outer rotor 71 and the outer roller 91 come into contact again, it is possible to prevent the smooth rotation of the rotating electric machine 61 from being hindered and drag loss from increasing, as in the first embodiment above.

[0114] (Other embodiments) The present invention is not limited to the embodiments, and can be implemented in various other forms without departing from the spirit or main characteristics thereof.

[0115] In each of the above embodiments, the present invention is applied to a permanent magnet synchronous rotating electric machine. However, the present invention is not limited to this. For example, the present invention may be applied to a rotating electric machine that does not have a permanent magnet, such as a switched reluctance motor or an induction motor having a cage-type conductor.

[0116] In the above embodiments, the "rotating body rotatably provided in the opening" is configured by the cylindrical rollers 30, 31, 90, 91, but this is not limiting, and the rotating body may be configured by the ball .

[0117] Furthermore, in each of the above embodiments, the rollers 30, 31, 90, and 91 are made of a magnetic material, but this is not limiting, and the rollers 30, 31, 90, and 91 may be made of a material with low magnetic permeability. Even in this case, the present invention allows the predetermined gaps G and G2 between the rotors 10, 11, 70, and 71 and the stator cores 21 and 81 to be made as narrow as possible, thereby increasing the torque density.

[0118] Furthermore, in the above-mentioned variant example 2, in the axial gap type rotating electric machine 1, the electromagnetic fluid 40 is interposed between the rollers 30, 31 and the rotors 10, 11, but this is not limited to this, and in the radial gap type rotating electric machine 61 in the above-mentioned embodiment 2, the electromagnetic fluid 40 may be interposed between the inner and outer rollers 90, 91 and the inner and outer rotors 70, 71.

[0119] As such, the above-described embodiments are merely examples in all respects and should not be interpreted as limiting. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0120] According to the present invention, it is possible to improve the efficiency of a rotating electrical machine, and therefore it is extremely useful when applied to a rotating electrical machine in which a plurality of rotors are arranged to sandwich a stator. [Explanation of symbols]

[0121] 1,1A,61 Rotating Electric Machine 3,63,64 Rotor shaft (rotating shaft) 10,11,70,71 rotors 20,20A,80 Stator 21,81 Stator core 24,84 opening 30, 30A, 31, 31A, 90, 91 Roller (rotating body) 40 Magnetohydrodynamics G,G2 Predetermined interval

Claims

1. A rotating electric machine including: a rotating shaft; a stator having an annular stator core coaxial with the rotating shaft; and a pair of rotors each connected to the rotating shaft with a predetermined gap between them and the stator core, the pair of rotors are provided facing each other in the axial direction so as to sandwich the stator core from both axial sides of the rotating shaft, or facing each other in the radial direction so as to sandwich the stator core from radially inner and outer sides of the rotating shaft, an opening formed in the stator core and penetrating in the opposing direction of the pair of rotors; A pair of rotors are rotatably provided within the opening so as to be aligned in the opposing direction, A rotating electric machine characterized in that the pair of rotating bodies contact each other within the opening, and the portion of each rotating body protruding outward in the opposing direction from the opening is configured to contact at least one of the pair of rotors.

2. 2. The rotating electric machine according to claim 1, The stator core is annular, the pair of rotors are provided opposite to each other in the axial direction so as to sandwich the stator core from both axial sides of the rotating shaft, the opening is formed in the stator core so as to penetrate therethrough in the axial direction, A rotating electric machine characterized in that the pair of rotating bodies are each rotatable radially and are arranged within the opening so as to be aligned axially, and the portions of each rotating body protruding outward in both axial directions from the opening are configured to come into contact with at least one of the pair of rotors.

3. 2. The rotating electric machine according to claim 1, The stator core is cylindrical, the pair of rotors are provided radially opposite to each other so as to sandwich the stator core from the radially inner and outer sides of the rotary shaft, The opening is formed in the stator core so as to penetrate therethrough in a radial direction, A rotating electric machine characterized in that the pair of rotating bodies are each rotatable around the axial direction and are arranged in the opening so as to be aligned radially, and the portions of each rotating body protruding radially inward and outward from the opening are configured to come into contact with at least one of the pair of rotors.

4. In the rotating electric machine according to any one of claims 1 to 3, A rotating electric machine characterized in that each of the rotating bodies is made of a magnetic material.

5. 5. The rotating electric machine according to claim 4, A rotating electric machine characterized in that an electromagnetic fluid is interposed between the rotating body and the rotor.

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