Synchronous electric rotating machine

Abstract

To easily assemble a magnet body and a yoke while counteracting a repulsive force, and to stably integrate the magnet body and the yoke by preventing magnetic saturation.SOLUTION: In a rotor in which magnet bodies 2 are arranged at equal angular intervals via a sector-shaped yoke 3 with the same poles facing each other, neodymium magnets with a magnetic flux density B of 150 mT≤B are used as magnet bodies 2, and the central angle θ of yoke 3 is set to 20°<θ<40°. When the side of magnet body 2 is viewed from a direction perpendicular to it, the peripheral edge of the side of yoke 3 protrudes from the peripheral edge of the side of magnet body 2 to join the side of magnet body 2 and the side of yoke 3. The relationship between the protruding dimension Ea of yoke 3 in the axial direction, the protruding dimension Eb on the other axial side, and the minimum gap G between adjacent magnet bodies 2 are set to 0.5 mm≤Ea≤5 mm, 0.5 mm≤Eb≤5 mm, and 0.5 mm≤G≤5 mm.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a synchronous rotating electric machine that can be configured as an electric motor or generator, and that has a ring-shaped rotor rotated by a rotating shaft and a stator arranged around the rotor, and in particular, to a synchronous rotating electric machine that has a so-called homopolar repulsion type rotor in which permanent magnets are arranged circumferentially via independent sector-shaped yokes so that like poles face each other. [Background technology]

[0002] Conventionally, an example of this type of synchronous rotating electric machine is disclosed in JP 6-38415 A (Patent Document 1), which, as shown in FIG. 31, comprises a ring-shaped rotor 100 rotated by a rotating shaft (not shown) and a stator (not shown) arranged around the rotor 100. The rotor 100 is configured to comprise magnet bodies 101 consisting of a plurality of permanent magnets formed into elongated rectangular parallelepipeds of the same shape and size, arranged at equal angular intervals (45°) with the same poles facing each other along a circumferential direction centered on the central axis P of the rotating shaft on the outside of the rotating shaft, and a plurality of yokes 102 arranged between adjacent magnet bodies 101, having sides that join the sides of magnet bodies 101, and formed to be the same shape and size in a sector shape with a predetermined central angle (45°).

[0003] Incidentally, in the case of a synchronous rotating electric machine Ka, for example, a motor (electric motor), it is desirable to use magnets with high magnetic flux density, such as neodymium magnets, instead of ferrite magnets as the magnet bodies 101 of the rotor 100 in order to obtain a motor with high energy efficiency. However, when attempting to design and inexpensively produce a rotor 100 using magnet bodies 101 with high magnetic flux density, as shown in FIG. 31, in a type of rotor 100 in which magnet bodies 101 are arranged in the circumferential direction via an independent yoke 102, there is no problem if the magnet bodies are ferrite magnets, but in the case of magnet bodies 101 with high magnetic flux density, the magnetic force is strong and the assembly and mounting process becomes difficult. For this reason, so-called IPM motors in which magnet bodies are embedded in an iron core as a rotor have been widely used (see, for example, JP Patent Publication No. 10-66285, etc.). However, in fields such as EVs and robots, for example, there is a demand for motors that are as light as possible and have high torque and high rotation speeds, and since rotors 100 of the type in which magnet bodies 101 are arranged circumferentially via independent yokes 102 have excellent torque density per unit weight, it is desirable for them to become more widespread. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-38415 [Patent Document 2] Japanese Patent Application Publication No. 10-66285 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, to give a detailed explanation of the problems with rotor 100 of the type in which magnet bodies 101 are arranged in the circumferential direction via independent yoke 102, as shown in Fig. 31, in this rotor 100, magnet bodies 101 are formed as elongated rectangular parallelepipeds, and the base of sector-shaped yoke 102 is wide, so that magnetic flux leaks and the magnetic flux density in the radial direction, where it is originally desired to increase, does not increase, and the magnetic flux inherent to the magnet cannot be effectively utilized, resulting in poor energy efficiency. For this reason, it is conceivable to narrow the base width of the sector-shaped yoke to drastically reduce the magnetic flux at the base of the yoke and increase the magnetic flux density in the radial direction, but on the other hand, this would make it more susceptible to magnetic saturation, and magnets of the same polarity would repel each other from this portion, which would result in a strong magnetic force during the above mounting process, making the assembly mounting process difficult.

[0006] The present invention has been made in consideration of these problems, and has as its object to provide a synchronous rotating electric machine which has a rotor in which permanent magnets are arranged circumferentially via independent sector-shaped yokes so that like poles face each other, and which, even when using high performance magnets such as neodymium magnets, allows the magnet bodies and yoke to be easily assembled while counteracting repulsive forces, effectively directs the magnetic flux radiated from the magnet bodies to the yoke, while at the same time preventing magnetic saturation, achieving an optimal structure for the high performance magnets and yoke, automatically stabilizing them magnetically, and allowing most of the magnetic flux density possessed by the high performance magnets to be absorbed by the yoke and released as magnetic flux that contributes to driving force, making the most of it. [Means for solving the problem]

[0007] The inventors of the present application conducted research for many years and investigated the relationship between high-performance magnets with high magnetic flux density and the yoke, and as a result discovered the conditions for achieving maximum efficiency without magnetic saturation, thereby completing the present invention. That is, the synchronous rotating electrical machine of the present invention for solving the above problems includes a ring-shaped rotor rotated by a rotating shaft and a stator provided around the rotor. The rotor includes a magnet body composed of a plurality of permanent magnets arranged at equal angular intervals with the same poles facing each other along the circumferential direction centered on the central axis of the rotating shaft outside the rotating shaft, and having the same shape and the same size, and a plurality of yokes arranged between adjacent magnet bodies, having side surfaces joined to the side surfaces of the magnet bodies, and formed in a fan shape having a predetermined central angle, the same shape, and the same size. In the synchronous rotating electrical machine configured as described above, the magnet body is composed of a magnet material with a magnetic flux density B satisfying 150 mT ≤ B, when the central angle of the yoke is θ, it is set to 20° < θ < 40°, when the axial length of the magnet body is Ma, the radial length is Mr, the axial length of the yoke is Ya, and the radial length is Yr, it is set to Ma < Ya and Mr < Yr, when the side surface of the magnet body is viewed from a direction orthogonal thereto, the side surface of the yoke is protruded from the peripheral edge of the side surface of the magnet body to join the side surface of the magnet body and the side surface of the yoke, when the protruding dimension of the axial one-side peripheral edge of the side surface of the yoke with respect to the axial one-side peripheral edge of the side surface of the magnet body is Ea, the protruding dimension of the axial other-side peripheral edge of the side surface of the yoke with respect to the axial other-side peripheral edge of the side surface of the magnet body is Eb, and the minimum distance between adjacent magnet bodies is G, it is set to 0.5 mm ≤ Ea ≤ 5 mm, 0.5 mm ≤ Eb ≤ 5 mm, and 0.5 mm ≤ G ≤ 5 mm. It is configured as described above.

[0008] Here, examples of the magnet material with 150 mT ≤ B include rare earth magnets. A rare earth magnet refers to a high-performance magnet formed by molding and then sintering a powder of rare earth metals (a total of 17 elements such as neodymium, samarium, and cobalt). There are samarium-cobalt Sm-Co-based magnets (commonly called samacoba magnets) and neodymium-iron-boron Nd-Fe-B-based magnets (commonly called neodymium magnets). The yoke is made of an appropriate material such as an iron-based material with a high saturation magnetic flux density, soft magnetic iron, pressed powder core, magnetic steel sheet, low carbon steel, silicon steel sheet, etc. If necessary, heat treatment may be performed, or anti-rust plating or painting may be performed.

[0009] As a result, when assembling the rotor, for example, the S pole side of one magnet body (one magnet body) is joined in advance to one side of one yoke, and the S pole side of another magnet body (the other magnet body) is joined to the other side of this yoke, as shown in Fig. 5. Alternatively, although not shown, the N pole side of one magnet body (one magnet body) is joined in advance to one side of one yoke, and the N pole side of another magnet body (the other magnet body) is joined to the other side of this yoke.

[0010] In this case, according to the present invention, even if one magnet body is temporarily unable to be attracted when an attempt is made to bring the other magnet body close to the yoke to which it is attracted in order to join their surfaces due to repulsion, if the other magnet body is brought even closer to join the surfaces, the magnetic flux of its S pole will be absorbed by the yoke, enabling the magnet bodies to be attracted. The reason for this is that in the present invention, as shown in Figure 6, the central angle θ of the yoke is set to 20°<θ<40°, and the minimum gap G between adjacent magnet bodies is set to 0.5mm≦G≦5mm, thereby narrowing the base width of the sector-shaped yoke, and further, when the side of the magnet body is viewed from a direction perpendicular to it, the peripheral edge of the side of the yoke protrudes from the peripheral edge of the side of the magnet body, that is, the peripheral edge of the yoke (the entire periphery of the yoke) protrudes beyond the peripheral edge of the magnet body (the entire periphery of the magnet body).In particular, as shown in Figures 6(b) and 7(a), the peripheral edge of the yoke protrudes by 0.5mm to 5mm from the peripheral edge of the magnet body not only in the radial direction but also in the axial direction.Therefore, when the other magnet body is brought even closer to the yoke and surface-joined, the magnetic flux of the S pole will be absorbed by the yoke.

[0011] If the yoke does not protrude in the axial direction relative to the magnet body, that is, if the one and other faces of the yoke perpendicular to the central axis direction and the one and other faces of the magnet body perpendicular to the central axis direction are flush (flat) in the axial direction as shown in Figure 7(b), high-performance magnets such as neodymium magnets are generally prone to chipping, and since the corners are chamfered with a radius (R), the magnetic flux is not absorbed by the yoke and leaks out from the radius part of the corners, and since the magnetic flux is easily saturated near the base of the yoke, the same poles of the magnet body facing the yoke tend to repel each other. Therefore, the yoke to which one magnet body is attracted does not absorb the entire magnetic flux generated from the S pole of the other magnet body, and as a result, the magnetic flux is magnetically saturated near the base of the yoke, and it cannot be attracted by repelling the S pole magnetic flux emitted from the surface of the yoke. Even if it is forcibly attached in this state, for example by adhesive or restrained by a restraining means, the magnetic flux cannot be used effectively, and there is little point in using a high magnetic flux density magnet. In the present invention, this phenomenon of repulsion and inability to adsorb can be avoided.

[0012] In this way, the magnet body and the yoke are assembled in order to make a ring-shaped rotor. In the assembled state, the base width of the sector-shaped yoke is narrow, and the periphery of the yoke protrudes from the periphery of the magnet body by 0.5mm to 5mm in both the radial and axial directions, so that the magnetic flux is absorbed and attracted by the yoke near the base of the yoke, which is prone to magnetic saturation, and similarly, the magnetic flux is absorbed and attracted by the yoke at the periphery of the entire yoke, so that the magnetic flux of the magnet can be led to the yoke. Therefore, the total magnetic flux density in the radial direction is much higher than that of the base of the yoke, and as a result, the magnetic flux density of the magnet body can be utilized with maximum efficiency. If it exceeds 5mm, the magnetic flux density tends to decrease, so it is desirable to set it to a range of 5mm or less where stable attraction is possible.

[0013] Based on the test results for yoke protrusion shown in Fig. 20, it is desirable to set the protrusion amount of the yoke from the magnet body to a range of 3 mm or less that allows stable adhesion. That is, preferably, 0.5 mm ≦ Ea ≦ 3 mm, 0.5 mm ≦ Eb ≦ 3 mm, 0.5 mm ≦ G ≦ 3 mm, and more preferably, 0.5 mm ≦ Ea ≦ 1 mm, 0.5 mm ≦ Eb ≦ 1 mm, 0.5 mm ≦ G ≦ 1 mm. Stable adhesion is not possible when Ea = 0. In order to make the most of the magnetic flux density of the magnet body with maximum efficiency, it is better for the upper limit to be as small as possible, but it can be set within the protrusion amount range that allows stable adhesion.

[0014] 14 to 19, it is known that when the central angle of the yoke is less than 20°, the magnetic flux at the base end of the yoke becomes saturated and cannot be attracted, and in the present invention, the central angle θ of the yoke is set to 20°<θ<40°, which reliably prevents the magnetic flux at the base end of the yoke from becoming saturated and unable to be attracted. If the central angle exceeds 40°, the magnetic flux density decreases. It is preferable that the central angle θ is 20°<θ≦36°.

[0015] For this reason, in the present invention, the magnet body can be stably attached to the yoke without being pressed down by an external force, allowing for stable mounting and assembly, improving productivity and reducing costs. In the assembled state, all the magnetic flux generated from the surface of the magnet body can be absorbed by the yoke, and the yoke can be magnetized to release the magnetic flux from the surface, making effective use of the magnetic flux of the high magnetic flux density magnet. In the present invention, a motor using a high performance magnet such as a neodymium magnet with a magnetic flux density of 150 mT or more can be driven with maximum efficiency per weight, and a motor that is easy to assemble, high torque, high efficiency, and light weight can be obtained.

[0016] If necessary, the protrusion dimension Ec of the radially outer periphery of the side surface of the yoke relative to the radially outer periphery of the side surface of the magnet body is set to 0.5 mm≦Ec≦5 mm. Desirably, 0.5 mm≦Ec≦3 mm, and more desirably, 0.5 mm≦Ec≦1 mm. When Ec=0, stable adhesion is poor. In order to utilize the magnetic flux density of the magnet body with maximum efficiency, it is better for the upper limit value to be as small as possible, but it can be set within the range of protrusion amount that allows stable adhesion. The projection dimension Ed of the radially inner periphery of the side surface of the yoke relative to the radially inner periphery of the side surface of the magnet body is set to 0.5 mm≦G≦5 mm, so it does not need to be specified in particular. However, it is preferable to make the projection dimension Ed as small as possible.

[0017] In addition, if necessary, the yoke has an angle of 25.7°≦θ<36°, and the number of the yokes is n, n=10, n=12, or n=14, and the magnet body is formed into a substantially rectangular parallelepiped shape. n is an even integer. n=10 (θ=36°), n=12 (θ=30°), or n=14 (θ≒25.7°). In the case of n=14, the central angle θ is not divisible, but this is within the margin of error in the adhesion between the magnet body and the yoke, and there is no effect on the action and effect, so there is almost no problem. If the gap is a concern, an adhesive or the like can be inserted. Within this range, the action and effect of the present invention can be maximized. As can be seen from the test example in FIG. 19, when n≦8, the total magnetic flux density cannot be used effectively. If n is 16 or less, the yoke becomes thin and becomes more susceptible to saturation.

[0018] Furthermore, if necessary, a protrusion is formed on the outer end of the side surface of the yoke, protruding in the circumferential direction, against which the outer end surface of the magnet body abuts. In the present invention, the magnet body and the yoke can be stably attracted to each other without the need to press the magnet body against the yoke with an external force, so the protrusion is not particularly necessary, but the magnet body can be positioned by abutting against the protrusion during assembly, making assembly even easier. Also, it is possible to reliably prevent misalignment due to centrifugal force when the rotor rotates.

[0019] Furthermore, if necessary, the rotor is configured to include a holder made of a non-magnetic material through which the rotating shaft is inserted and fixed, and which holds the base ends of the yokes. Since the rotating shaft can be fixed to the holder, the axial alignment between the rotating shaft and the rotor is ensured. Therefore, the rotor can be attached to the rotating shaft reliably and easily. When the rotating shaft is rotated, the rotor can rotate smoothly. Furthermore, since the base ends of the yokes are held by the rotor during rotation, it is possible to reliably prevent deviation due to centrifugal force during rotation of the rotor, and the rotor can rotate smoothly.

[0020] Specifically, as necessary, the rotor is configured to include a holder made of a non-magnetic material formed in a ring shape through which the rotating shaft is inserted and fixed, the holder holding the base ends of each of the yokes on its outer periphery, and the inner end of the yoke is provided with an engaging portion that protrudes circumferentially to the left and right, and the holder has an engaged portion formed on its outer periphery with which the engaging portion is inserted from one side or the other side perpendicular to the central axis of the holder to engage.

[0021] As a result, when assembling the rotor, for example, a required number of first units are prepared in advance, each having the N-pole side of one magnet body bonded to one side of one yoke to expose the S-pole side of the magnet body, and a required number of second units are prepared in advance, each having the S-pole side of one magnet body bonded to one side of one yoke to expose the N-pole side of the magnet body, and these first and second units are joined alternately in order. In this case, first, either the first or second unit is attached to the holder by engaging the engaging portion of the yoke with the engaged portion of the holder. Next, the other of the first or second unit is attached to the holder by engaging the engaging portion of the yoke with the engaged portion of the holder.

[0022] In this case, the magnet body of either the first unit or the second unit slides onto the other side of the yoke of either the first unit or the second unit to be joined, and at the beginning of the sliding, they temporarily repel each other as they are of the same polarity and cannot be attracted to each other, but as described above, if they are further slid closer together and surface-joined, the magnetic flux of the magnet body is absorbed by the yoke, and they can be attracted to each other. In this way, the first unit and the second unit are joined in alternating order. At this time, it is only necessary to engage the engaging portion of the yoke with the engaged portion of the holder and push it in, so positioning can be easily performed and assembly can be easily performed.

[0023] Next, the rotor holder is attached to the rotating shaft. In this case, since the holder can be fixed to the rotating shaft, the axial alignment between the rotating shaft and the rotor is ensured. Therefore, the rotor can be attached to the rotating shaft reliably and easily. Then, when the rotating shaft is rotated, the rotor can rotate smoothly. Furthermore, since the engaging portion of the yoke engages with the engaged portion of the holder during rotation, it is possible to reliably prevent misalignment due to centrifugal force when the rotor rotates, and the rotor can rotate smoothly.

[0024] Also, as necessary, the rotor may be configured to include a holder having a pair of plates made of a non-magnetic material, into which the rotating shaft is inserted and fixed, and which are attached to one and the other faces of each of the yokes perpendicular to the central axis, respectively, to hold the base end of each of the yokes, a first bolt insertion hole is formed in the base end of each of the yokes along the axial direction of the rotating shaft, a plurality of second bolt insertion holes corresponding to the first bolt insertion holes are formed in each of the plates of the holder, bolts made of a non-magnetic material are inserted into the second bolt insertion holes of the one plate, the first bolt insertion holes of each of the yokes and the second bolt insertion holes of the other plate, and nuts made of a non-magnetic material are screwed onto each bolt, so that each of the yokes is held by the pair of plates.

[0025] As a result, when assembling the rotor, for example, a required number of first units are prepared in advance, in which the N-pole side of one magnet body is joined to one side of one yoke to expose the S-pole side of the magnet body, and a required number of second units are prepared in advance, in which the S-pole side of one magnet body is joined to one side of one yoke to expose the N-pole side of the magnet body, and these first and second units are joined in an alternating order. In this case, the first and second units are attached by inserting bolts into the second bolt insertion holes of one plate of the holder. Then, first, either the first or second unit is attached to one plate by inserting bolts into the first bolt insertion holes of the yoke. Next, the other of the first or second unit is attached to one plate by inserting bolts into the first bolt insertion holes of the yoke.

[0026] In this case, the magnet body of the other of the first unit or the second unit slides onto the other side of the yoke of either the first unit or the second unit to be joined. At the beginning of the sliding, they are of the same polarity and repel each other temporarily, so that they cannot be attracted to each other. However, as described above, if they are further slid closer to each other and surface-joined, the magnetic flux of the magnet body is absorbed by the yoke, so that they can be attracted to each other. In this way, the first unit and the second unit are joined in turn. At this time, it is only necessary to insert the bolt into the first bolt insertion hole of the yoke and push it in, so that the positioning can be easily performed and the assembly can be easily performed. Finally, the other plate is attached by inserting the bolt into its second bolt insertion hole and screwing a nut onto the bolt. As a result, each yoke is sandwiched between the pair of plates.

[0027] Next, the rotor holder is attached to the rotating shaft. In this case, since the holder can be fixed to the rotating shaft, the axis alignment between the rotating shaft and the rotor is ensured. Therefore, the rotor can be attached to the rotating shaft reliably and easily. Then, when the rotating shaft is rotated, the rotor can rotate smoothly. Also, during rotation, each yoke is sandwiched between a pair of plates with a bolt inserted into the first bolt insertion hole, so that deviation due to centrifugal force during rotation of the rotor can be reliably prevented, and the rotor can rotate smoothly. Also, since the first bolt insertion hole is formed at the base end of the yoke, and the width of the base end of the yoke is effectively reduced due to the increase in magnetic resistance caused by the use of a non-magnetic bolt, the magnetic flux of the magnet can be easily guided to the yoke.

[0028] Furthermore, as required, the stator may be a radially positioned stator having a plurality of stator coils arranged at predetermined intervals on a circumference centered on the rotation axis of the rotor and facing the outer peripheral surface of the rotor via an air gap.

[0029] In addition, as necessary, the stator may be configured to include an axial position stator having a plurality of stator coils arranged at predetermined intervals on a circumference centered on the rotation axis of the rotor and facing one side and / or the other side perpendicular to the central axis of the rotor via an air gap.

[0030] Furthermore, as necessary, the stator may be configured to include a radial position stator having a plurality of stator coils that face the outer peripheral surface of the rotor via an air gap and are arranged in a row at predetermined intervals on a circumference centered on the rotation axis of the rotor, and an axial position stator that faces one side and / or the other side perpendicular to the central axis of the rotor via an air gap and has a plurality of stator coils that are arranged in a row at predetermined intervals on a circumference centered on the rotation axis of the rotor.

[0031] As a result, since the radial position stator and the axial position stator are provided, the stator coil can easily capture the magnetic flux of the rotor, thereby improving the efficiency of the synchronous rotating electric machine. For example, if a motor uses a high-performance magnet such as a neodymium magnet with a magnetic flux density of 150 mT or more, a highly efficient motor can be obtained.

[0032] Furthermore, as required, the stator may be a radial position stator having a plurality of stator coils arranged at predetermined intervals on a circumference centered on the rotation axis of the rotor and facing the outer circumferential surface of the rotor via an air gap, and a plurality of teeth provided corresponding to the plurality of stator coils, respectively, around which the stator coils are wound, The teeth of the radial position stator are configured to include a main body facing the outer peripheral surface of the rotor via an air gap, and a convex strip protruding from both ends of the main body in the central axial direction toward the central axis and having facing portions facing one side and the other side of the rotor via an air gap, and the stator coil is wound around the teeth with at least the facing portions of the convex strip exposed.

[0033] As a result, the teeth of the radial position stator are configured with a main body facing the outer circumferential surface of the rotor and a convex body having a facing portion facing one side and the other side of the rotor, so that the stator coil can easily capture the magnetic flux of the rotor, thereby improving the efficiency of the synchronous rotating electric machine. For example, if a motor uses a high-performance magnet such as a neodymium magnet with a magnetic flux density of 150 mT or more, a highly efficient motor can be obtained.

[0034] In this case, it is effective to interpose a non-magnetic insulating member between the main body and the ridges, so that the magnetic flux density radiated from the main body facing the outer circumferential surface of the rotor and the ridges having facing portions facing one side and the other side of the rotor can be balanced.

[0035] In this case, it is effective to arrange a plurality of rotor and stator sets in a row on the same rotating shaft. As a result, the magnetic flux density absorbed by the yoke from the high performance magnet and radiated from the outer circumferential surface of the rotor and the facing portions facing one side and the other side of the rotor can be guided to the stator coil to the maximum extent, improving the efficiency of the synchronous rotating electric machine. For example, if a motor uses a high performance magnet such as a neodymium magnet with a magnetic flux density of 150 mT or more, a highly efficient motor can be obtained. Effect of the Invention

[0036] According to the present invention, even if a high-performance magnet such as a neodymium magnet is used, the magnet body and the yoke can be easily assembled while counteracting the repulsive force. In addition, the magnetic flux radiated from the magnet body can be effectively guided to the yoke, and at the same time, magnetic saturation can be prevented, and the high-performance magnet and the yoke can be stably integrated, and the magnetic flux density of the high-performance magnet can be maximized. This allows the motor to be used as a highly efficient electric motor (motor) or generator equipped with a ring-shaped rotor and a stator provided around the rotor. In particular, the motor is ideal for applications where the external dimensions are limited and weight reduction is required, such as small and slender spindle motors, motors mounted on the arm joints of robots or the ends of the arms of robots, medical motors, etc., and by using these, the motors are extremely useful for machine tools, robots, handy-type manual tools, various medical devices, drones, etc., where small and lightweight are desired. [Brief description of the drawings]

[0037] [Figure 1] 1A is an exploded perspective view showing a rotor and a stator of a synchronous rotating electric machine according to a first embodiment of the present invention, and FIG. 1B is a perspective view showing the rotor and the stator in an assembled state. [Diagram 2] 1 is an exploded perspective view showing a structure of a rotor of a synchronous rotating electric machine according to a first embodiment of the present invention; [Diagram 3] 1 is a diagram showing a rotor of a synchronous rotating electric machine according to a first embodiment of the present invention; [Figure 4] 1 is a cross-sectional view showing a relationship between a rotor of a synchronous rotating electric machine according to a first embodiment of the present invention and a stator that is circumferentially surrounding the rotor via an air gap. [Diagram 5] FIG. 2 shows the basic structure of the magnet bodies and yokes and their relationship in the rotor of a synchronous rotating electric machine of the present invention, where (a) is a front view showing a state before one magnet body is attracted to the yoke to which the other magnet body is attracted, and (b) is a front view showing a state in which one magnet body has been attracted to the yoke to which the other magnet body is attracted. [Figure 6]FIG. 1 shows the basic structure of the magnet bodies and yoke and their relationship in a rotor for a synchronous rotating electric machine of the present invention, where (a) is a front view showing a state in which one magnet body is attracted to a yoke to which the other magnet body is attracted, and (b) is a side view seen from a direction perpendicular to the side of the yoke. [Figure 7] FIG. 6(a) shows a cross-sectional view taken along line AA in FIG. 6(a) of the present invention in which the yoke protrudes axially from the magnet body, and FIG. 7(b) shows a cross-sectional view equivalent to FIG. 7(a) in which the yoke does not protrude axially from the magnet body. [Figure 8] FIG. 4 is a perspective view showing a synchronous rotating electric machine according to a second embodiment of the present invention. [Figure 9] FIG. 11 is a cross-sectional view showing a modified example of a synchronous rotating electric machine according to the second embodiment of the present invention. [Figure 10] FIG. 11 is a front view showing a synchronous rotating electric machine according to a third embodiment of the present invention. [Figure 11] 10A shows a synchronous rotating electric machine according to a fourth embodiment of the present invention, in which (a) is a front view showing a rotor and a stator, (b) is a cross-sectional view showing one rotor and one stator assembled together (single axial type), and (c) is a cross-sectional view showing two rotors and one stator assembled together (double axial type). [Figure 12] FIG. 13 is a diagram showing a synchronous rotating electric machine according to a fifth embodiment of the present invention, and illustrating the relationship between a rotor and a stator. [Figure 13] FIG. 4 is an exploded perspective view showing another example of the rotor in the synchronous rotating electric machine according to each embodiment of the present invention. [Figure 14] FIG. 13 is a diagram showing a state in which one magnet body is attracted to a yoke to which the other magnet body is attracted, in relation to the magnetic flux density sensor, in Test Example 1 of the present invention (a test relating to the relationship between the distance between the magnet body and the yoke and the magnetic flux density on the yoke surface). [Figure 15] FIG. 1 is a graph showing the measurement results of Test Example 1 of the present invention. [Figure 16]FIG. 11 is a graph showing the measurement results of Test Example 2 of the present invention (measurement of magnetic flux density on the surface of a yoke and on the surface of a magnet body). [Figure 17] FIG. 11(a) relates to Test Example 3 of the present invention (Test <Part 1> on the central angle θ of the yoke), and is a diagram showing the state in which one magnetic body is attracted to a yoke to which the other magnetic body is attracted, in relation to the measurement site of the magnetic flux density sensor (the center of the outer circumferential part spreading in the radial direction of the sector), and FIG. 11(b) is a graph showing the results of measuring the magnetic flux density for different central angles of the yoke. [Figure 18] FIG. 11A is a diagram showing the measurement sites of a magnetic flux density sensor, and FIG. 11B is a graph showing the results of measuring the magnetic flux density for different central angles of the yoke, relating to Test Example 4 (Test <part 2> for the central angle θ of the yoke) of the present invention. [Figure 19] FIG. 11 is a graph showing the results of calculating the total magnetic flux intensity by multiplying the magnetic flux strength per unit of the magnet body by the number of poles (the number of yokes) for each different central angle of the yoke in Test Example 5 of the present invention (Test <Part 3> for the central angle θ of the yoke). [Figure 20] FIG. 14 is a graph showing the measurement results of magnetic flux density for yokes having different axial widths with respect to the magnet body (the magnetic flux density was measured at the same positions as in Test Example 1 (FIG. 14)) in Test Example 6 of the present invention (a test on the protrusion amount of the yoke with respect to the magnet body). [Figure 21] FIG. 13 is a graph showing the results of measuring the relationship between thickness and magnetic flux density of a neodymium magnet, in Test Example 7 of the present invention (test on the thickness of the magnet body (the circumferential length Me of the magnet body)). [Figure 22] FIG. 11A is a diagram showing measurement sites of a magnetic flux density sensor, and FIG. 11B is a graph showing the measurement results for each holder material, relating to Test Example 8 (test on holder material) of the present invention. [Diagram 23] FIG. 13(a) is a graph showing the results of measuring the relationship between the yoke angle and magnetic flux density for different combinations of neodymium magnet size and yoke size in Test Example 9 of the present invention (test on rotor size), and FIG. 13(b) is a table showing the underlying data. [Figure 24]FIG. 13 is a diagram showing different combinations (a), (b), (c), and (d) of the size of the neodymium magnet and the size of the yoke in relation to the area ratio of the yoke and the surface area ratio of the actual yoke (shaded area) in Test Example 9 (test on rotor size) of the present invention. [Diagram 25] FIG. 13 is a diagram visually illustrating the concept of the torque-to-weight ratio coefficient F per unit weight for a yoke and two neodymium magnets sandwiching the yoke in an analysis for determining the optimal rotor size for obtaining maximum torque per weight, relating to Test Example 9 (test on rotor size) of the present invention. [Figure 26] FIG. 4 is a graph showing the relationship between magnet length Mr and torque-to-weight ratio coefficient F. [Figure 27] 1A, 1B, and 1C are diagrams showing a prototype of a rotor that can be used in a synchronous rotating electric machine according to each embodiment of the present invention. [Figure 28] 1A is a perspective view showing a first embodiment (prototype 1: radial gap motor), FIG. 1B is a perspective view showing a second embodiment (prototype 2: single axial gap motor), and FIG. 1C is a perspective view showing a third embodiment (prototype 3: double axial gap motor) of the present invention. [Figure 29] FIG. 10 is a table showing the test results of Examples 1 to 3 and the estimated values ​​of Example 4 in Test Example 10 (torque measurement test for the embodiments) of the present invention, and FIG. 10 is a table showing the data of Comparative Examples 1 to 7 (commercially available motors 1 to 7). [Diagram 30] FIG. 13 is a diagram showing a modified example of a rotor according to an embodiment of the present invention. [Diagram 31] FIG. 1 is a diagram showing a rotor of a conventional synchronous rotating electric machine together with problems associated therewith. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A synchronous rotating electric machine according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 1 to 4 show a synchronous rotating electric machine K according to a first embodiment of the present invention. This synchronous rotating electric machine K includes a ring-shaped rotor 1 rotated by a rotating shaft S (FIG. 4) and a radial position stator 20 as a stator provided around the rotor 1.

[0039] The rotor 1 is composed of a magnet body 2 consisting of a plurality of permanent magnets of the same shape and size arranged at equal angular intervals on the outside of the rotating shaft S with the same poles facing each other along the circumferential direction centered on the central axis P of the rotating shaft S, a plurality of yokes 3 arranged between adjacent magnet bodies 2, having sides that join to the sides of the magnet bodies 2 and formed in a sector shape of the same shape and size with a predetermined central angle, and a holder 10 made of a non-magnetic material through which the rotating shaft S is inserted and fixed, and which holds the base end of each yoke 3.

[0040] The magnet body 2 is made of a magnet material with a magnetic flux density of 150mT≦B, where B is the magnetic flux density. An example of a magnet material with a magnetic flux density of 150mT≦B is a rare earth magnet. A rare earth magnet is a high-performance magnet made by molding and then sintering rare earth metal powder (a total of 17 elements, including neodymium, samarium, and cobalt). There are samarium-cobalt Sm-Co magnets (commonly known as samarium-cobalt magnets) and neodymium-iron-boron Nd-Fe-B magnets (commonly known as neodymium magnets). In the embodiment, a neodymium magnet is used. The magnet body 2 is formed in a substantially rectangular parallelepiped shape.

[0041] For the yoke 3, an appropriate material is selected, for example, an iron-based material with high magnetic permeability and high saturation magnetic flux density, soft magnetic iron, pressed powder core, low carbon steel, silicon steel plate, etc. If necessary, heat treatment may be performed, or anti-rust plating or painting may be performed.

[0042] When the central angle of the yoke 3 is θ, it is set such that 20° < θ < 40°. Desirably, 20° < θ ≤ 36°. More desirably, it is in the range of 25.7° < θ ≤ 36°. When the number of yokes 3 is n, it is either n = 10, n = 12, or n = 14. In the embodiment, n = 10 (θ = 36°). At the outer end of the side surface of the yoke 3, a protruding piece 4 is formed along the circumferential direction to abut against the outer end surface of the magnet body 2. At the inner end of the yoke 3, an engaging portion 5 protruding left and right in the circumferential direction is provided. On the other hand, on the holder 10, an engaged portion 6 is formed into which the engaging portion 5 is inserted and engaged from one side or the other side perpendicular to the central axis P of the holder 10. The base end portion 7 of the yoke 3 and the engaging portion 5 are integrally formed and are formed in a substantially T shape. On the other hand, the engaged portion 6 is formed in a concave shape so that the T-shaped portion composed of the base end portion 7 and the engaging portion 5 of the yoke 3 fits. In the embodiment, the engaged portion 6 is formed in 10 pieces at equal angular intervals in accordance with the number of yokes 3 (n = 10).

[0043] Then, as shown in FIG. 6, when the axial length of the magnet body 2 is Ma, the radial length is Mr, the axial length of the yoke 3 is Ya, and the radial length is Yr, Ma < Ya and Mr < Yr are set. When the side surface of the magnet body 2 is viewed from a direction perpendicular thereto, the peripheral edge of the side surface of the yoke 3 protrudes from the peripheral edge of the side surface of the magnet body 2, and the side surface of the magnet body 2 and the side surface of the yoke 3 are joined. In the embodiment, since the yoke 3 has the engaging portion 5 described above, the radial length Yr of the yoke 3 is set including the engaging portion 5. For example, for the rotor 1, its radius R (FIG. 3) is about 20 mm ≤ R ≤ 80 mm, and it is set to 5 mm ≤ Ya ≤ 100 mm and 5 mm ≤ Yr ≤ 55 mm. Also, the circumferential length Me (thickness) of the magnet body 2 varies depending on the size of the radius R, but is set to 2 mm ≤ Me ≤ 20 mm. Also, from Test Example 9 described later, the size of the magnet body 2 is optimally 8 mm ≤ Ma ≤ 10 mm and 5 mm ≤ Mr ≤ 25 mm. The dimensions of each part are not limited to these.

[0044] Furthermore, when the protruding dimension of the periphery on one axial side of the side of the yoke 3 relative to the periphery on one axial side of the side of the magnet body 2 is Ea, the protruding dimension of the periphery on the other axial side of the side of the yoke 3 relative to the periphery on the other axial side of the side of the magnet body 2 is Eb, and the minimum distance between adjacent magnet bodies 2 (between the adjacent inner peripheries of a pair of magnet bodies 2 joined to one yoke 3) is G, the values ​​are set to 0.5mm≦Ea≦5mm, 0.5mm≦Eb≦5mm, and 0.5mm≦G≦5mm. Desirably, 0.5mm≦Ea≦3mm, 0.5mm≦Eb≦3mm, and 0.5mm≦G≦3mm, and more desirably, 0.5mm≦Ea≦1mm, 0.5mm≦Eb≦1mm, and 0.5mm≦G≦1mm.

[0045] Furthermore, when the protruding dimension Ec of the radially outer periphery of the side surface of the yoke 3 relative to the radially outer periphery of the side surface of the magnet body 2 is set to 0.5mm≦Ec≦5mm. Preferably, 0.5mm≦Ec≦3mm, and more preferably, 0.5mm≦Ec≦1mm. Stable adhesion is not possible when Ec=0. In order to make the most of the magnetic flux density of the magnet body with maximum efficiency, it is better for the upper limit to be as small as possible, but it can be set within the range of protrusion amount that allows stable adhesion.

[0046] The projection dimension Ed of the radially inner periphery of the side surface of the yoke 3 relative to the radially inner periphery of the side surface of the magnet body 2 is set to 0.5 mm≦G≦5 mm, and does not need to be specified in particular. However, it is desirable to make the projection dimension Ed as small as possible. In the embodiment, since the engagement portion 5 is provided, the projection dimension Ed is set to include the engagement portion 5.

[0047] The radial position stator 20 as a stator is configured to include a plurality of (12 in the embodiment) stator coils 21 arranged at predetermined intervals on a circumference centered on the rotation axis S of the rotor 1 and facing the outer peripheral surface of the rotor 1 via an air gap, and a plurality of (12 in the embodiment) teeth 22 provided corresponding to the plurality of stator coils 21, respectively, around which the stator coils 21 are wound. The teeth 22 are fixed to a frame 23 made of a non-magnetic material formed in a ring shape surrounding the rotor 1.

[0048] As shown in Fig. 4, the teeth 22 of the radial position stator 20 are configured to include a main body 24 facing the outer circumferential surface of the rotor 1 via an air gap, and a protruding strip 25 protruding from both ends of the main body 24 in the direction of the central axis P toward the central axis P and having a facing portion 25a facing one side and the other side of the rotor 1 via an air gap. A non-magnetic insulating member 26 is interposed between the main body 24 and the protruding strip 25. The stator coil 21 is wound around a radial axis Q that is perpendicular to the central axis P and passes through the main body 24, with at least the facing portion 25a of the protruding strip 25 exposed to the teeth 22.

[0049] 2, when assembling the rotor 1, for example, a required number of first units U1 are prepared in advance, each having the N-pole side of one magnet body 2 joined to one side of one yoke 3 and the S-pole side of the magnet body 2 exposed, and a required number of second units U2 are prepared in advance, each having the S-pole side of one magnet body 2 joined to one side of one yoke 3 and the N-pole side of the magnet body 2 exposed. In this case, the magnet body 2 can be positioned by abutting against the protrusion 4 during assembly, making assembly even easier.

[0050] Then, the first unit U1 and the second unit U2 are alternately assembled in order to the holder 10. In this case, first, either the first unit U1 or the second unit U2 is attached to the holder 10 by engaging the engaging portion 5 of its yoke 3 with the engaged portion 6 of the holder 10. Next, the other of the first unit U1 or the second unit U2 is attached to the holder 10 by engaging the engaging portion 5 of its yoke 3 with the engaged portion 6 of the holder 10.

[0051] At this time, the magnet body 2 of either the first unit U1 or the second unit U2 slides and joins to the other side surface of the yoke 3 of either the first unit U1 or the second unit U2, but at the beginning of the sliding, they are of the same polarity and repel each other, so they cannot be attracted to each other. However, this is a temporary occurrence, and if they are further slid and brought closer together for surface joining, the magnetic flux of the magnet body 2 is absorbed by the yoke 3, so they can be attracted to each other. In this way, the first unit U1 and the second unit U2 are joined in an alternating order. Therefore, it is only necessary to engage and push the engaging portion 5 of the yoke 3 into the engaged portion 6 of the holder 10, so that positioning can be easily performed and assembly can be easily performed.

[0052] In detail, although there occurs a state in which the magnets cannot be attracted due to repulsion between the same poles, they can be attracted by bringing them even closer together and joining them by surface contact, as shown in FIG. 6. In this embodiment, the central angle θ of the yoke 3 is set to 20°<θ<40°, and the minimum gap G between adjacent magnet bodies 2 is set to 0.5mm≦G≦5mm, thereby narrowing the base width of the sector-shaped yoke 3, and further, when the side surface of the magnet body 2 is viewed from a direction perpendicular to the side surface of the yoke 3, the peripheral edge of the side surface of the yoke 3 protrudes from the peripheral edge of the side surface of the magnet body 2. That is, the periphery of the yoke 3 (the entire periphery of the yoke 3) is configured to protrude beyond the periphery of the magnet body 2 (the entire periphery of the magnet body 2), and in particular, as shown in Figures 6(b) and 7(a), the periphery of the yoke 3 protrudes beyond the periphery of the magnet body 2 by 0.5mm to 5mm in both the radial and axial directions, so that when one magnet body 2 is brought even closer to the yoke 3 to which the other magnet body 2 is attracted and surface-joined, the magnetic flux of the S pole of the other magnet body 2 is absorbed by the yoke 3. Also, the protruding dimension Ec of the radially outer periphery of the side surface of the yoke 3 relative to the radially outer periphery of the side surface of the magnet body 2 is set to 0.5mm≦Ec≦5mm, so that stable attraction can also be achieved in this respect.

[0053] In this manner, the magnet bodies 2 and the yoke 3 are successively assembled to form the ring-shaped rotor 1. In assembling the rotor 1, the magnet bodies 2 can be stably attracted to the yoke 3 without being pressed down by an external force, and thus the rotor 1 can be stably mounted and assembled, improving productivity and reducing costs. Then, the holder 10 of the rotor 1 is attached to the rotating shaft S. In this case, the holder 10 can be fixed to the rotating shaft S, so that the axial alignment between the rotating shaft S and the rotor 1 is ensured. Therefore, the rotor 1 can be attached to the rotating shaft S reliably and easily. The rotor 1 is then assembled together with the stator 20 to complete the synchronous rotating electric machine K.

[0054] In this synchronous rotating electric machine K, the root width of the sector-shaped yoke 3 in the rotor 1 is narrow, and the periphery of the yoke 3 protrudes from the periphery of the magnet body 2 by 0.5 mm to 5 mm in both the radial and axial directions, so that the magnetic flux can be guided to the yoke 3. Therefore, as shown in FIG. 6, the total magnetic flux density in the radial direction is much higher than that at the root (base end 7) of the yoke 3, and as a result, the magnetic flux density of the magnet body 2 can be utilized with maximum efficiency. That is, in the rotor 1, the total magnetic flux generated from the surface of the magnet body 2 can be absorbed by the yoke 3, and the yoke 3 can be magnetized to emit the magnetic flux from the surface, so that the magnetic flux of the high magnetic flux density magnet can be effectively utilized. For example, a motor using a high-performance magnet such as a neodymium magnet with a magnetic flux density of 150 mT or more can be driven with maximum efficiency per weight, and a motor that is easy to assemble, has high torque, is highly efficient, and is lightweight can be obtained.

[0055] Furthermore, since the outer end of the side surface of the yoke 3 is formed with a protrusion 4 that protrudes in the circumferential direction and abuts against the outer end surface of the magnet body 2, it is possible to reliably prevent the magnet body 2 from shifting due to the centrifugal force when the rotor 1 rotates. Also, since the engaging portion 5 of the yoke 3 engages with the engaged portion 6 of the holder 10, it is possible to reliably prevent the yoke 3 from shifting due to the centrifugal force when the rotor 1 rotates, and the rotation can be performed smoothly.

[0056] Furthermore, the stator includes a radial position stator 20, and the teeth 22 of the radial position stator 20 are configured with a main body 24 facing the outer circumferential surface of the rotor 1 and a convex strip 25 having a facing portion 25a facing one side and the other side of the rotor 1, so that the stator coil 21 can easily capture the magnetic flux of the rotor 1, thereby improving the efficiency of the synchronous rotating electric machine K. For example, if a motor uses a high-performance magnet such as a neodymium magnet with a magnetic flux density of 150 mT or more, a highly efficient motor can be obtained. In addition, a non-magnetic insulating member 26 is interposed between the main body 24 and the convex strip 25, so that the magnetic flux density radiated from the main body 24 and the convex strip 25 can be balanced.

[0057] FIG. 8 shows a synchronous rotating electric machine K according to the second embodiment. This is configured by arranging a plurality of sets of the rotor 1 and the stator 20 according to the first embodiment in a row on the same rotating shaft S. This improves the efficiency of the synchronous rotating electric machine K. For example, if a motor uses a high-performance magnet such as a neodymium magnet with a magnetic flux density of 150 mT or more, a highly efficient motor can be obtained. This configuration is particularly effective in cases where the motor diameter is not required to be large but high torque is desired.

[0058] Fig. 9 shows a modified example of a synchronous rotating electric machine K according to the second embodiment. In this example, the teeth 22 of each stator 20 shown in Fig. 8 are integrated, the ridges 25 of adjacent teeth 22 are shared, and the stator coil 21 is wound around the entire ridges 25 with the opposing portions 25a of the ridges 25 exposed. This allows the motor to effectively utilize the magnetic flux generated from both sides of the ridges 25, effectively utilizing electrical energy, and increasing the torque per unit weight.

[0059] 10 shows a synchronous rotating electric machine K according to a third embodiment. This machine includes a radial position stator 20 as a stator, and this radial position stator 20 faces the outer circumferential surface of the rotor 1 via an air gap and includes a plurality of stator coils 21 (12 in the embodiment) arranged at predetermined intervals on a circumference centered on the rotation axis S of the rotor 1, and a plurality of teeth 22 (12 in the embodiment) provided corresponding to the plurality of stator coils 21 and around which the stator coils 21 are wound. The teeth 22 are fixed to the inside of a frame 27 made of a non-magnetic material formed in a ring shape surrounding the rotor 1.

[0060] FIG. 11 shows a synchronous rotating electric machine K according to a fourth embodiment. As shown in FIG. 11(a), the axial position stator 30 is provided as a stator. The axial position stator 30 has one surface and the other surface that face a surface perpendicular to the central axis P of the rotor 1 via an air gap, and is provided with a plurality of (12 in the embodiment) stator coils 21 arranged at a predetermined interval on a circumference centered on the rotation axis S of the rotor 1, and a plurality of (12 in the embodiment) teeth 22 around which the stator coils 21 are wound, which are provided corresponding to the plurality of stator coils 21. The rotor 1 is provided with one surface perpendicular to the central axis P of the rotor 1, and is fixed to a disk 31 centered on the central axis P. FIG. 11(b) shows an example (single axial type) in which the axial position stator 30 is fixed to a fixed body (not shown), one rotor 1 is attached to the rotation axis S, and the rotor 1 is provided facing one surface of the axial position stator 30. FIG. 11(c) shows an example (double axial type) in which the axial position stator 30 is fixed to a fixed body (not shown), and two rotors 1 are attached to a rotating shaft S with the axial position stator 30 sandwiched between them, with one rotor 1 facing one side of the axial position stator 30 and the other rotor 1 facing the other side of the axial position stator 30.

[0061] 12 shows a synchronous rotating electric machine K according to the fifth embodiment. This is configured to include the radial position stator 20 of the synchronous rotating electric machine K according to the third embodiment and the axial position stator 30 of the synchronous rotating electric machine K according to the fourth embodiment. This makes it possible to improve the efficiency of the synchronous rotating electric machine K. For example, if a motor uses a high-performance magnet such as a neodymium magnet with a magnetic flux density of 150 mT or more, a highly efficient motor can be obtained.

[0062] FIG. 13 shows another example of the rotor in the synchronous rotating electric machine according to each of the above-mentioned embodiments. In this rotor 1, the shape of the holder is different from that of the rotor in each of the above-mentioned embodiments. More specifically, this rotor 1 is configured with a holder 40 having a pair of plates 41 made of a non-magnetic material, into which a rotating shaft (not shown) is inserted and fixed, and which are attached to one surface and the other surface of the rotor 1 perpendicular to the central axis P and hold the base end of each yoke 3. A first bolt insertion hole 42 is formed in the base end of each yoke 3 along the axial direction of the rotating shaft P, while each plate of the holder 40 has a plurality of second bolt insertion holes 43 corresponding to the first bolt insertion holes 42. Then, a bolt 44 made of a non-magnetic material is inserted into the second bolt insertion hole 43 of one plate 41, the first bolt insertion hole 42 of each yoke 3, and the second bolt insertion hole 43 of the other plate 41, and a nut (not shown) made of a non-magnetic material is screwed onto each bolt 44, and each yoke 3 is sandwiched between the pair of plates 41.

[0063] As a result, when assembling the rotor 1, for example, a required number of first units U1 in which the N-pole side of one magnet body 2 is joined to one side of one yoke 3 to expose the S-pole side of the magnet body 2 and a required number of second units U2 in which the S-pole side of one magnet body 2 is joined to one side of one yoke 3 to expose the N-pole side of the magnet body are prepared in advance, and the first units U1 and the second units U2 are joined alternately in order. In this case, the bolts 44 are inserted into the second bolt insertion holes 43 of one plate 41 of the holder 41 to attach them. Then, first, either the first unit U1 or the second unit U2 is attached to one plate 41 by inserting the bolts 44 into the first bolt insertion holes 42 of the yoke 3. Next, the other of the first unit U1 or the second unit U2 is attached to one plate 41 by inserting the corresponding bolts 44 into the first bolt insertion holes 42 of the yoke 3.

[0064] In this case, the other magnet body 2 of either the first unit U1 or the second unit U2 slides and joins to the other side surface of the yoke 3 of either the first unit U1 or the second unit U2. At the beginning of the slide, they have the same polarity and repel each other temporarily, so that they cannot be attracted to each other. However, as described above, if they are further slid and brought closer to each other for surface joining, the magnetic flux of the magnet body 2 is absorbed by the yoke 3, so that they can be attracted to each other. In this way, the first unit U1 and the second unit U2 are joined in turn. At this time, it is only necessary to insert the bolt 44 into the first bolt insertion hole 42 of the yoke 3 and push it in, so that the positioning can be easily performed and the assembly can be easily performed. Finally, the other plate 41 is attached by inserting the bolt 44 into its second bolt insertion hole 43 and screwing a nut onto the bolt 44. As a result, each yoke 3 is sandwiched between the pair of plates 41.

[0065] Next, the holder 40 of the rotor 1 is attached to the rotating shaft S. In this case, since the holder 40 can be fixed to the rotating shaft S, the axis alignment between the rotating shaft S and the rotor 1 is ensured. Therefore, the rotor 1 can be attached to the rotating shaft S reliably and easily. Then, when the rotating shaft S is rotated, the rotor 1 can be rotated smoothly. Also, during rotation, each yoke 3 is sandwiched between a pair of plates 41 with the bolt 44 inserted into the first bolt insertion hole 42, so that deviation due to centrifugal force during rotation of the rotor 1 can be reliably prevented, and rotation can be performed smoothly. Also, since the first bolt insertion hole 42 is formed at the base end of the yoke 3, and the non-magnetic bolt 44 penetrates through it, the magnetic resistance increases, and the effect of the through hole is multiplied to substantially reduce the width of the base end of the yoke 3, so that the magnetic flux of the magnet can be easily guided to the yoke.

[0066] <Test Example> Next, test examples supporting the present invention will be described. (1) Test Example 1 (Test on the relationship between the distance between the magnet body 2 and the yoke 3 and the magnetic flux density on the surface of the yoke 3) Using the symbols shown in Fig. 6, a neodymium magnet with Ma = 10 mm, Mr = 20 mm, Me = 8 mm (B = 430 mT) was used as the magnet body 2. The yoke 3 was made of SS400 (iron material) with Ya = 11 mm, Yr = 22 mm (without the engagement portion 5), and six types were prepared with central angles θ of 20°, 25°, 30°, 40°, 60°, and 80° (Fig. 15).

[0067] As shown in Fig. 14, a pair of different types of magnet bodies 2 was attached to both sides of the yoke 3 with the same poles facing each other for each yoke 3 with different central angles θ, and the magnetic flux density on the surface of the yoke 3 was measured. The measuring device used was "MT-801" manufactured by Mother Tool Co., Ltd. In attaching the magnet bodies 2, one magnet body 2 was first attached to the yoke 3, and in this state the other magnet body 2 was brought closer to the side of the yoke 3, and the magnetic flux density on the surface of the yoke 3 was measured when the distance was 100 mm, 40 mm, 20 mm, 10 mm, 5 mm, and 2.5 mm. Since the thickness of the magnetic flux density sensor was about 2 mm, a gap of 2.5 mm was left and the central angle θ of the yoke 3 was changed for measurement.

[0068] The results are shown in Figure 15. Initially, the magnetic flux density of one of the magnet bodies 2 (A), which was attached to the yoke 3 first, was emitted from the surface of the yoke 3, but as the other magnet body 2 (B) approached, the magnetic flux density of magnet body 2 (B) began to be effectively absorbed by the yoke 3, causing the relationship to reverse. From around 5 mm away, yokes 3 with a central angle θ of 25° or more, which have a large volume and magnetic flux absorption capacity, produce a magnetic force and magnetic flux density that attracts magnet body 2 (B). At a distance of 2.5 mm, yokes 3 with a central angle θ of other than 20° generate a strong attractive force, but a yoke 3 with a central angle θ of 20° does not attract magnet body 2 (B) even when it is completely close due to magnetic saturation of the yoke 3.

[0069] (2) Test Example 2 (Measurement of magnetic flux density on the surface of the yoke 3 and the surface of the magnet body 2) In the combination of the magnet body 2 and the yoke 3 in the test example 1, the magnetic flux density on the surface of the yoke 3 and the magnetic flux density on the surface of the magnet body 2 (B) were measured by changing the central angle θ of the yoke 3. The results are shown in FIG. 16. From these results, it was possible to observe the details of the closest state (2.5 mm) of the magnet body 2 (B) for the yoke 3 with a central angle θ of 20°. That is, it was found that in the yoke 3 with a central angle θ of 20°, the magnetic flux density on the surface of the yoke 3 was 380 mT, and the magnetic flux density of the surface of the magnet body 2 (B), 420 mT, could not be completely absorbed. The reason for this is that the yoke 3 with a central angle θ of 20° has a small volume, so it cannot completely absorb the magnetic flux density of the combined magnet body 2 (A) and magnet body 2 (B). Therefore, in the case of the yoke 3 with a central angle θ of 20°, the magnetic flux density of the magnet body 2 (B) is not induced to the opposite pole, and the magnetic force density to attract is insufficient, so it is repelled by the same pole of the magnet body 2 (A). On the other hand, in a yoke 3 with a central angle θ of 25° or more, the surface magnetic flux density of the magnet body 2 (B) flows sufficiently into the yoke 3, and the surface of the yoke 3 is induced to the opposite pole (S), allowing magnetic adsorption.

[0070] (3) Test Example 3 (Test on the central angle θ of the yoke 3 <Part 1>) Three types of magnet bodies 2 were prepared as test pieces: a neodymium magnet (B=430mT), a neodymium magnet (B=153mT), and a ferrite magnet (B=143mT). Using the symbols shown in Fig. 6, magnet bodies 2 with Ma=10mm, Mr=20mm, and Me=8mm were used. Nine types of yokes 3 with Ya=11mm, Yr=22mm (without engaging portion 5) and central angles θ ranging from 20° to 80° and differing in increments of 5° were prepared (Fig. 17(b)).

[0071] Then, as shown in Fig. 17(a), for each yoke 3 with a different central angle θ, a pair of different types of magnet bodies 2 was attached to both sides of the yoke 3 with the same poles facing each other, and the magnetic flux density was measured at the center of the outer periphery part that spread in the radial direction of the sector shape of the yoke 3. The measuring device used was "MT-801" manufactured by Mother Tool Co., Ltd. In attaching the magnet bodies 2, one magnet body 2 was first attached to the yoke 3, and in this state the other magnet body 2 was brought close to the side of the yoke 3 and attached.

[0072] The measurement results are shown in Figure 17(b). When the central angle θ of the yoke 3 was 20°, the ferrite magnet was attracted, but in the case of the neodymium magnet, the magnetic flux at the base end X of the yoke 3 was saturated and it was not possible to attract either magnet. However, when the magnet bodies 2 had a central angle θ of 25° or more, they were temporarily unable to be attracted when they were brought close to each other due to repulsion, but were able to be attracted when they were brought even closer. This is because when one magnet body 2 is brought close to the yoke 3 to which the other magnet body 2 is attracted, the magnetic flux of the S pole of the other magnet body 2 is absorbed by the yoke 3. Furthermore, when the central angle θ is 35° or more, the magnetic flux density tends to decrease.

[0073] (4) Test Example 4 (Test on the central angle θ of the yoke 3 <part 2>) As the test specimens, similar to Test Example 1, a neodymium magnet with Ma = 10 mm, Mr = 20 mm, Me = 8 mm (B = 430 mT) was used as the magnet body 2. Five types of yokes 3 (without engaging portion 5) made of SS400 (iron material) with Ya = 11 mm, Yr = 22 mm were prepared with central angles θ of 20°, 25°, 30°, 40°, and 60° (Fig. 18(b)).

[0074] Then, as shown in FIG. 18(a), the magnetic flux density on the radial surface (outer periphery) of the yoke 3 and the magnetic flux density at the axial position (a point 5 mm inside from the outer periphery on one and the other surfaces perpendicular to the central axis P) were measured for each yoke 3 having a different central angle θ using the same measuring device as described above.

[0075] The measurement results are shown in Figure 18(b). In this figure, there is only one broken line at the bottom, but because the magnetic flux density is approximately the same on the radial surface, axial surface 1 (one surface), and axial surface 2 (the other surface), these broken lines overlap. When the central angle θ of the yoke 3 was 20°, the magnetic flux was saturated in all cases and adhesion was not possible. As a result, it can be seen that the relationship between the total magnetic flux density and the central angle θ of the yoke 3 also shows that magnet body 2 with a central angle θ of 25° or more is favorable.

[0076] (5) Test Example 5 (Test on the central angle θ of the yoke 3 <Part 3>) Using the same test specimen as in Test Example 3, the total magnetic flux intensity for the total number of magnetic poles was calculated by multiplying the magnetic flux intensity per unit of the magnet body 2 by the number of poles (the number of yokes 3), and the relationship between this and the central angle θ of the yoke 3 was examined. The results are shown in Fig. 19.

[0077] From the results of Test Examples 3 to 5, it is considered that the central angle θ of the yoke 3 is appropriate in the range of 20°<θ<40°, and if it exceeds 40°, the magnetic flux density decreases. Preferably, it is 20°<θ≦36°. In practice, from the results of Test Example 5, taking into consideration the surface area of ​​the yoke 3 and the number of poles (number of yokes 3), it can be assumed that 10 poles (θ=36°), 12 poles (θ=30°), and 14 poles (θ≒25.7°) can effectively use the magnetic flux density of the neodymium magnet. If the central angle θ is widened, the number of poles decreases and the total magnetic flux density decreases at the same time, resulting in a decrease in efficiency. If the central angle θ is 20°, the magnetic flux saturates the yoke 3 and is not absorbed, and the magnetic flux density of the magnet body 2 cannot be effectively used, resulting in inefficiency. That is, it was found that the preferable configuration is one in which the angle of the yoke 3 is in the range of 25.7°<θ≦36°, n is an even integer number, and n=10 (θ=36°), n=12 (θ=30°), or n=14 (θ≒25.7°). When n=14, the central angle θ is not divisible, but this is within the margin of error in the adhesion between the magnet body 2 and the yoke 3, does not affect the function and effect, and is almost poses no problem. If gaps are a concern, an adhesive or similar can be used.

[0078] Furthermore, from the results of Test Example 4, it can be seen that since the magnetic flux densities of the radial surface, axial surface 1 (one side), and axial surface 2 (the other side) are approximately the same, in the fifth embodiment, the radial position stator 20 and the axial position stator 30 face the radial surface, axial surface 1 (one side), and / or axial surface 2 (the other side), respectively, and therefore, it can be seen that the fifth embodiment is extremely efficient.

[0079] (6) Test Example 6 (Test on the protrusion amount of the yoke 3 relative to the magnet body 2) The test pieces for the magnet body 2 were neodymium magnets (B=430mT) with Ma=10mm, Mr=20mm, and Me=8mm. The yoke 3 had Yr=22mm (without the engaging portion 5) and three different central angles θ of θ=30°, θ=60°, and θ=80°. Four different axial widths were prepared: Ya=10mm (Ea+Eb=0mm), Ya=11mm (Ea+Eb=1mm), Ya=12mm (Ea+Eb=2mm), and Ya=13mm (Ea+Eb=3mm) (Fig. 20).

[0080] Then, for each yoke 3, a pair of magnet bodies 2 was attached to both sides of the yoke 3 with the same poles facing each other, and the magnetic flux density at the center of the outer periphery that spread in the radial direction of the sector of the yoke 3 was measured using the same measuring device as above. Note that in this test, when the side of the magnet body 2 is viewed from a direction perpendicular to it, the peripheral edge of the side of the yoke 3 protrudes from the peripheral edge of the side of the magnet body 2 to join the side of the magnet body 2 and the side of the yoke 3.

[0081] The results are shown in Figure 20. The magnetic flux density was higher in the case where the yoke 3 did not protrude from the magnet body 2 (Ea+Eb=0mm in total on both sides) than in the case where the yoke 3 did not protrude from the magnet body 2, but this was because the magnet body 2 was forcibly pressed down into an attracted state, and in reality it is not possible to attract it. The case where the yoke 3 protruded from the magnet body 2 was able to be stably attracted. It was also found that the magnetic flux density decreased as the protrusion amount increased. If the yoke 3 protrudes too much, the volume of the yoke 3 increases, increasing the surface area and decreasing the magnetic flux density. The circumferential magnetic flux density of the yoke 3 decreased by 10% with just 1mm of protrusion on both sides in total. Furthermore, a decrease in magnetic flux density was observed in the case where the central angle θ of the yoke 3 was large (θ=60°, θ=80°) compared to the case where the central angle was small (θ=30°).

[0082] From these results, it can be said that the protrusion amount of the periphery of the yoke 3 relative to the periphery of the magnet body 2 is 0.5mm≦Ea≦5mm, 0.5mm≦Eb≦5mm, preferably 0.5mm≦Ea≦3mm, 0.5mm≦Eb≦3mm, and more preferably 0.5mm≦Ea≦1mm, 0.5mm≦Eb≦1mm.

[0083] From this, it can be said that it is preferable to set the protruding dimension Ec of the radially outer peripheral edge of the side surface of the yoke 3 to 0.5 mm≦Ec≦5 mm, preferably 0.5 mm≦Ec≦3 mm, and more preferably 0.5 mm≦Ec≦1 mm.

[0084] The protruding dimension Ed of the radially inner circumferential edge of the side surface of the yoke 3 is set to 0.5 mm≦G≦5 mm, so it does not need to be specified in particular. However, it is preferable to make the protruding dimension Ed as small as possible.

[0085] (7) Test Example 7 (Test on the thickness of magnet body 2 (circumferential length Me of magnet body 2)) The relationship between thickness and magnetic flux density of neodymium magnets was measured. The results are shown in Figure 21. From these results, it can be seen that with neodymium magnets, although they can fall below 150mT, there is practical value in a magnet exceeding 150mT, which cannot be achieved with ferrite. Magnetic flux density improves by increasing thickness, but considering efficiency per weight, it is best to keep it in the region of 6mm≦Me≦10mm. In other words, magnet thicknesses Me of 2mm to 20mm can be used, but the range of 6mm to 10mm is preferable.

[0086] (8) Test Example 8 (Test on the material of the holder 10) As shown in Fig. 22, the material of the holder 10 was tested for the rotor 1 (10 poles) similar to the first embodiment. As shown in Fig. 27(c) described later, the rotor 1 used a neodymium magnet as the magnet body 2 with Ma = 10 mm, Mr = 20 mm, Me = 8 mm (B = 430 mT). The yoke 3 was prepared with SS400 (iron material), Ya = 11 mm, Yr = 22 mm (with an engagement portion 5), and a central angle θ of 36°. Three types of holders 10 were made using the following materials: general structural rolled steel (SS400), stainless steel (SUS304), and aluminum alloy (A5052) (FIG. 22(b)).

[0087] Then, for three types of rotors 1 (10 poles) created using each of these different types of holders 10, the magnetic flux density of the outer peripheral surface (surface A) of the yoke 3, the outer portion (surface B) of one surface perpendicular to the central axis P of the yoke 3, and the inner portion (surface C) of one surface perpendicular to the central axis P of the yoke 3 was measured using the same measuring device as above, as shown in Figure 22(a).

[0088] The results are shown in Figure 22(b). From these results, it can be said that by using a non-magnetic material for the holder, it is possible to prevent magnetic flux leakage from the base of the yoke, and that this has the effect of improving the magnetic flux density in the radial circumferential direction on the most important opposite side of the yoke and the magnetic flux density on the axial surface by more than 10%.

[0089] (9) Test Example 9 (Test on rotor size) (9-1) Rotor inner circumference radius (Ra) From the results of Test Example 7, if the minimum Me = 6 mm is selected from 6 mm ≦ Me ≦ 10 mm, and the minimum G = 0.5 mm is selected from 0.5 mm ≦ G ≦ 5 mm, the inner radius Ra of the rotor is approximately Ra≒(Me+G)×Number of poles / 2π (Formula 1) Because it is okay to From equation 1, the circumference of the rotor's inner circle is approximately 65 mm (radius approximately 10 mm) for 10 poles (θ=36°). The maximum case is when there are 14 poles (θ≒25.7°), Me is at its maximum of 10 mm, and G is at its maximum of 5 mm, resulting in a circumference of approximately 210 mm (radius of approximately 35 mm). Therefore, in the case of neodymium magnets, the optimum range for the radius (Ra) of the rotor's inner circumference is approximately 10 mm to approximately 35 mm.

[0090] (9-2) Radius of the rotor circumference (R) Then, the diameter (radius R) of the rotor's outer circumference can be determined by considering the length of the magnet (Mr). First, as shown in FIG. 23, a neodymium magnet (2a) with Ma=10mm, Mr=10mm, Me=10mm and a neodymium magnet (2b) with Ma=10mm, Mr=20mm, Me=10mm were used to measure the relationship between the yoke angle (θ) and the magnetic flux density at the center of the outer circumference part that spreads in the radial direction of the sector of the yoke in the above manner. As a result, the neodymium magnet (2a) is prone to magnetic saturation due to the small size of the yoke, and adhesion becomes difficult at a yoke angle (θ) of 20° or 25°, and adhesion becomes possible from 30°. The neodymium magnet (2b) is difficult to magnetically saturate due to the large size of the yoke, and adhesion does not occur at a yoke angle (θ) of 20°, but sufficient adhesion can be obtained at 25°.

[0091] We also confirmed the relationship between the length of the magnet (Mr), the yoke, and the radial magnetic flux density. From the results in Figure 23, we can see that the magnetic flux density decreases as the angle of the yoke increases and the volume increases. For example, when comparing the yoke (θ=30°), referring to Figures 24(b) and (c), the size (volume) of the neodymium magnet is twice as large as that of the yoke with the neodymium magnet (2a) and the yoke with the neodymium magnet (2b), but the size (volume) of the yoke is four times as large. As a result, the efficiency drops drastically when the volume of the yoke increases. Looking at the actual measured values, the magnetic flux density at the center of the yoke using the neodymium magnet (2a) is 332 mT, and the magnetic flux density at the center of the yoke using the neodymium magnet (2b) is 285 mT. Despite doubling the size of the magnet, the magnetic flux density drops to about 85%. This is because, although magnetic saturation is less likely to occur in a yoke that uses a neodymium magnet (2b), the magnetic flux is fully absorbed within the yoke and diffused throughout, resulting in a significant reduction in the magnetic flux density that appears at the center of the yoke. As can be seen from the results in Figure 23, this reduction in magnetic flux density of approximately 85% is not limited to when the yoke angle θ is 30°, but is common to all angles θ. This rate of reduction can be improved by using a material with good magnetic permeability. It is hoped that high-permeability materials will be developed as yoke materials.

[0092] Next, we analyzed the factor relationships that determine the optimal rotor size to obtain the maximum torque per weight. We performed the analysis for (A) the case where the stator (called the radial type) according to the embodiment shown in Fig. 1 was assumed, and (B) the case where the stator (called the axial type) according to the embodiment shown in Fig. 11(a) was assumed.

[0093] (A) In the case of assuming a stator (radial type) according to the embodiment shown in FIG. 1 As shown in FIG. 25, the torque-to-weight ratio coefficient per unit weight of the yoke and the two neodymium magnets sandwiching it is F, and this is expressed as follows: F≒(R×B×H)÷(M+Y)=[(Ra+Mr)×B×H]÷(M+Y) ...(Formula 2) It was defined as follows.

[0094] Where: F: Torque-to-weight ratio coefficient Mr: The radial length of the magnet body Ra: Radius of the inner circumference of the rotor. Here, the radius is 15 mm. R (≒Ra + Mr): Radius of the rotor circumference H: Surface area ratio of actual yoke (surface area ratio contributed by stator). Here, assuming a stator according to the embodiment shown in Fig. 1, the maximum length of the convex stripes 25 of the teeth 22 is about 10 mm, and as shown in Fig. 24, the surface area of ​​the yoke using neodymium magnets (2a) (Fig. 24(b)) is set to 2 for easy understanding by adding up the axial and radial surfaces. That is, in Fig. 24(b), since the shaded parts of the yoke are on the front and back, the shaded parts on the front and back are set to 1, and the radial circumferential surface of the yoke (not shown) is set to 1, and these are added together to get 2.

[0095] M: weight ratio of neodymium magnets. Here, the weight of the neodymium magnet (2a) was set to 2. Y: weight ratio of the yoke. Here, the weight of the yoke using the neodymium magnet (2a) is set to 1. B(=0.85 n): magnetic flux density ratio of the yoke. Here, based on the results of Figure 23 above, it is assumed that the magnetic flux density drops to approximately 85% each time the length Mr of the neodymium magnet increases by 10 mm, and n is set to 0 when a neodymium magnet (2a) is used (magnetic flux density ratio B of the yoke is set to 1), and 1 is added to n for each 10 mm increase in length Mr. When a neodymium magnet (2b) is used, the length Mr is 20 mm, so n = 1, and so B = 0.85. When the length Mr is 30 mm, n = 2, so B = (0.85) 2 =0.72.

[0096] In the case of a yoke using two neodymium magnets, when the length Mr of the neodymium magnet is 5 mm, 10 mm (in the case of a yoke using two neodymium magnets (2a)), 20 mm (in the case of a yoke using two neodymium magnets (2b)), 30 mm, 40 mm, or 50 mm, and the torque-to-weight ratio coefficients are Fa to Ff, the calculation using Equation 2 gives the following results. In the case of a neodymium magnet with a magnet length Mr of 5 mm, since it is difficult to form teeth on the side surface, the specific surface area H is set to 0.5 and the magnet weight ratio M is set to 1.0 compared to one with a magnet length Mr of 10 mm. Fa ≒ [(15 + 5) × 1.17 × 0.5] ÷ (1.0 + 0.25) ≒ 9.4 Fb ≒ [(15 + 10) × 1 × 2] ÷ (2 + 1) ≒ 16.7 Fc ≒ [(15 + 20) × 0.85 × 5] ÷ (4 + 4) ≒ 18.6 Fd ≒ [(15 + 30) × 0.72 × 8] ÷ (6 + 9) ≒ 17.3 Fe ≒ [(15 + 40) × 0.61 × 11] ÷ (8 + 16) ≒ 15.4 Ff ≒ [(15 + 50) × 0.51 × 14] ÷ (10 + 25) ≒ 13.3

[0097] When these results are graphed, the relationship between magnet length Mr and torque weight ratio coefficient is as shown in Figure 26(a). Figure 26(b) also shows the relationship between magnet length Mr and torque (the numerator part related to torque in the calculation formula for torque weight ratio coefficient). For example, it is expected that the torque of a rotor using neodymium magnet (2b) will increase proportionally compared to a rotor using neodymium magnet (2a), but there is no simple proportional relationship. That is, in the torque weight ratio coefficient calculation formula, each element of the numerator related to torque (torque in this case) is a linear function, and as the magnet length increases, this numerator increases linearly as shown in Figure 26(b). The yoke weight in the denominator is a quadratic function, so the torque weight ratio coefficient is maximum for lengths of 10 to 20 mm as shown in Figure 26(a), and as the magnet size increases, the denominator increases and gradually decreases.

[0098] (B) In the case of assuming a stator according to the embodiment shown in FIG. 11(a) (called an axial type), Here, the torque ratio coefficient is calculated in the same way as above, but since the axial type has a large stator that is close to the size of the yoke, the value for the weight ratio of the yoke is taken into consideration and set to 2Y. Also, the length of the magnet Mr is replaced by the length to the center of gravity of the yoke where torque is generated L. The actual yoke surface area H is set to the area of ​​the part of the stator that actually faces the coil. The rest is the same as above.

[0099] Therefore, the torque-to-weight ratio coefficient F per unit weight of the yoke and the two neodymium magnets sandwiching it is: F≒(R×B×H)÷(M+2Y)=[(Ra+L)×B×H]÷(M+2Y) ...(Formula 3) It becomes.

[0100] Similarly, in the case of a yoke using two neodymium magnets, when the neodymium magnet length Mr is 5 mm (L = 3 mm), 10 mm (L = 7 mm), 20 mm (L = 14 mm), 30 mm (L = 20 mm), 40 mm (L = 24 mm), and 50 mm (L = 32 mm), the torque-to-weight ratio coefficients are Fa to Ff, and the calculation using Equation 2 gives the following results. Fa ≒ [(15 + 3) × 1.17 × 0.2] ÷ (1.0 + 0.5) ≒ 2.8 Fb ≒ [(15 + 7) × 1 × 0.75] ÷ (2 + 2) ≒ 4.1 Fc ≒ [(15 + 14) × 0.85 × 3.5] ÷ (4 + 8) ≒ 7.2 Fd ≒ [(15 + 20) × 0.72 × 8] ÷ (6 + 18) = 8.4 Fe ≒ [(15 + 24) × 0.61 × 15] ÷ (8 + 32) ≒ 8.9 Ff ≒ [(15 + 32) × 0.51 × 23] ÷ (10 + 50) ≒ 9.2

[0101] When these results are graphed, the relationship between magnet length Mr and torque-to-weight ratio coefficient is as shown in Figure 26(c). Additionally, Figure 26(d) shows the relationship between magnet length Mr and torque (the numerator involved in torque in the calculation formula for torque-to-weight ratio coefficient). In the case of the axial type (Figure 11(a)), it can be seen that the yoke area increases quadratically in relation to the magnet length. For magnet lengths up to 30mm, the radial type (Figure 1) is advantageous, but for large-diameter motors with magnet lengths exceeding 40mm, the axial type (Figure 11(a)) and double axial type (Figure 11(b)) are said to be effective.

[0102] (9-3) Summary To summarise the above results, under the conditions of 6mm≦Me≦10mm and 0.5mm≦G≦5mm, the rotor's inner circumference radius Ra can be in the range of approximately 10mm to 35mm, and the rotor's radial length Mr of the magnet body can be in the range of 5mm to 50mm, and as a result, it was found that a range of 15mm to 85mm for the rotor's outer circumference radius R is suitable. Furthermore, when taking advantage of the characteristics of the slender shape, there is an advantage to using a length Mr of 5mm. EXAMPLES

[0103] Next, an example will be described. First, a rotor as shown in FIG. 27 was created. The rotor has the structure shown in FIG. 2 and FIG. 3, and has 10 poles using a yoke with a central angle θ of 36°. The rotor shown in FIG. 27(a) has a diameter of 40 mm, the neodymium magnet has a length (Mr) of 5 mm, a width (Ma) of 10 mm, and a thickness (Me) of 6 mm, and a magnetic flux density of 460 mT. The rotor shown in FIG. 27(b) has a diameter of 50 mm, the neodymium magnet has a length (Mr) of 10 mm, a width (Ma) of 10 mm, and a thickness (Me) of 8 mm. The rotor shown in FIG. 27(c) has a diameter of 70 mm, and the neodymium magnet has a length (Mr) of 20 mm, a width (Ma) of 10 mm, and a thickness (Me) of 8 mm.

[0104] Then, as shown in Fig. 28, prototype motors (Examples 1 to 3) were created using the rotor and stator according to the embodiment shown in Fig. 10 and Fig. 11. In each example, the rotor 1 used was the rotor shown in Fig. 27(a) (diameter R is 40 mm, neodymium magnet has length (Mr) 5 mm × width (Ma) 10 mm × thickness (Me) 6 mm, and magnetic flux density 460 mT).

[0105] <Example 1 (Prototype: (Radial Gap Motor)> As shown in Figure 28(a), this is of the type shown in Figure 10, and is equipped with a rotor 1 and a radial position stator 20, as well as a base 50, a pair of bearing bodies 51 that support both ends of a rotating shaft S to which the rotor 1 is fixed halfway in the axial direction, and a fixed body 52 that is provided on the base 50 and fixes the radial position stator 20.

[0106] <Example 2 (Prototype 2: Single axial gap motor)> 28(b), this is a single axial type shown in Fig. 11(b), and includes one rotor 1 and axial position stator 30, as well as a base 50, a pair of bearing bodies 51 that support both ends of a rotating shaft S that is provided on the base 50 and has the rotor 1 fixed midway in the axial direction, and a fixed body 52 that is provided on the base 50 and fixes the axial position stator 30. The rotor 1 is provided facing one surface of the axial position stator 30.

[0107] <Example 3 (Prototype 3: Double axial gap motor)> 28(c), this is a double axial type shown in FIG. 11(c), and includes two rotors 1 and an axial position stator 30, a base 50, a pair of bearing bodies 51 that support both ends of a rotating shaft S that is attached to the base 50 and has two rotors 1 fixed to the middle of the axial direction, and a fixed body (not shown) that is attached to the base 50 and fixes the axial position stator 30. The two rotors 1 are attached to the rotating shaft S with the axial position stator 30 sandwiched between them, with one rotor 1 facing one side of the axial position stator 30 and the other rotor 1 facing the other side of the axial position stator 30.

[0108] <Example 4 (hypothetical example)> This is a hypothetical motor with the structure shown in Figure 1 (single radial + double axial).

[0109] In these Examples 1 to 3, a current was passed through the stator coil, a load was applied to the rotating shaft, and the maximum torque was measured. Example 4 (hypothetical) was estimated from the measurement results of Examples 1 to 3. The maximum torque per unit weight was also calculated. Furthermore, since the weight of the exterior and shaft is added to the mounted motor, the maximum torque per unit weight was also calculated taking into account a weight increase of 100g for (shaft + exterior) (shown in parentheses). The results are shown in Figure 29(a). Also, Figure 29(b) shows the maximum torque and maximum torque per unit weight for seven types of commercially available motors as comparative examples.

[0110] From these results, it was found that the motors to which the present invention was applied (Examples 1 to 4) all had a higher maximum torque per unit weight than the commercially available motors (Comparative Examples 1 to 7). In addition, as can be seen from the results and calculations of Example 3 (Test Machine 3), it was also found that high efficiency was possible by adopting a double axial type.

[0111] From these results, in the case of a rotor using a neodymium magnet with a length (Mr) of 20 mm shown in Figure 27(c), it is assumed from the magnet length and torque ratio coefficient test in Figure 26(b) that the simple torque value when using a neodymium magnet with a length (Mr) of 20 mm is 148, so by performing proportional calculation from the torque value of 12 for a magnet with a length (Mr) of 5 mm, it is assumed that approximately 10 times the torque can be obtained. Therefore, for example, with a motor with the structure shown in Figure 1, it is assumed that a torque of approximately 10 N·m can be generated when driven at 24 V, and the weight of the motor with the exterior can be reduced to approximately 500 g. Furthermore, when a double rotor is used (see Figure 8), the weight including the exterior is equivalent to approximately 1 kg, and it is thought that a torque of approximately 20 N·m can be obtained. If the driving voltage is increased, for example to 50 V, a high output of 40 N·m can be achieved with a motor weighing 1 kg.

[0112] In addition, based on the magnet length and torque-to-weight ratio coefficient in FIG. 26(a), it is assumed that the motor with the configuration shown in FIG. 1 has the best efficiency per weight ratio when using a neodymium magnet with a magnet length (Mr) of 20 mm. If weight is not a consideration, it is possible to further increase the magnet length to 50 mm. However, when considering the torque rise and maximum rotation speed, it is considered that a motor using a rotor (see FIG. 8) with a rotor diameter of about 20 mm in magnet length (Mr) combined in multiple stages, a combination with an axial type (see FIG. 11), or a configuration with multiple stages of this is effective. For this reason, it can be said that the present invention is extremely useful for spindle motors with large torque per weight, small and slender external shapes, and machine tools, robots, hand tools, drones, etc., where small and lightweight are desired.

[0113] In the rotor 1 of the synchronous rotating electric machine K according to the above embodiment, the magnet body 2 is formed in a rectangular parallelepiped shape, but this is not necessarily limited to this, and for example, as shown in FIG. 30, it may be sector-shaped (with a central angle α) and may be modified as appropriate. The number of yokes 3 (the number of poles) is also not limited to the above number and may be modified as appropriate. Furthermore, in the above embodiment, the shape of the holder 10 is not limited to the above and may be modified as appropriate. In short, the present invention is not limited to the above-described embodiment of the present invention, and those skilled in the art can easily make many modifications to these exemplary embodiments without substantially departing from the novel teachings and effects of the present invention, and these many modifications are included in the scope of the present invention. [Industrial Applicability]

[0114] According to the present invention, it is possible to utilize and make use of a highly efficient electric motor or generator having a ring-shaped rotor and a stator arranged around the rotor, and this is extremely useful for spindle motors that have a large torque per weight, a small and slender external shape, and for machine tools, robots, hand tools, drones, etc., where small and lightweight are desired. [Explanation of symbols]

[0115] K Synchronous rotating motor S Rotation axis 1 rotor P center axis 2. Magnet body 3. York θ central angle 4 prongs 5 Engagement part 6 Engaged part 7 Proximal end 10 Holder 20 Radial Position Stator 21 Stator coil 22 Teeth 23 Frame 24 Main Unit 25 Convex strip 25a Facing part 26 Non-magnetic insulating materials U1 1st Unit U2 2nd Unit 27 Frame 30 Axial Position Stator 31 Disc 40 Holder 41 Plate 42 First bolt hole 43 Second bolt hole 44 Volts 50 Base 51 Bearing body 52 Fixed body

Claims

1. A synchronous rotating electric machine comprising a ring-shaped rotor rotated by a rotating shaft and a stator provided around the rotor, the rotor being configured with magnet bodies made of a plurality of permanent magnets of the same shape and size arranged at equal angular intervals with like poles facing each other along a circumferential direction centered on the central axis of the rotating shaft on the outside of the rotating shaft, and a plurality of yokes arranged between adjacent magnet bodies, having sides joining to the sides of the magnet bodies, and formed in a sector shape with a predetermined central angle, the same shape and the same size, The magnet body is made of a magnet material having a magnetic flux density of 150 mT or less, where B is the magnetic flux density of the magnet body; When the central angle of the yoke is θ, the central angle is set to 20°<θ<40°, Let Ma be the axial length of the magnet body, Mr be the radial length thereof, and Ya be the axial length of the yoke, Yr be the radial length thereof, so that Ma<Ya and Mr<Yr are satisfied. when the side surface of the magnet body is viewed in a direction perpendicular to the side surface of the magnet body, the peripheral edge of the side surface of the yoke is caused to protrude from the peripheral edge of the side surface of the magnet body, and the side surface of the magnet body and the side surface of the yoke are joined together; Let Ea be the protruding dimension of the peripheral edge of the side surface of the yoke in the axial direction relative to the peripheral edge of the side surface of the magnet body in the axial direction on one side, Eb be the protruding dimension of the peripheral edge of the side surface of the yoke in the axial direction on the other side relative to the peripheral edge of the side surface of the magnet body in the axial direction on the other side, and G be the minimum distance between adjacent magnet bodies, A synchronous rotating electric machine, characterized in that: 0.5 mm≦Ea≦5 mm, 0.5 mm≦Eb≦5 mm, and 0.5 mm≦G≦5 mm.

2. 2. The synchronous rotating electric machine according to claim 1, wherein when a protruding dimension Ec of the radially outer peripheral edge of the side surface of the yoke relative to a peripheral edge on the radially outer end side of the side surface of the magnet body is set to 0.5 mm≦Ec≦5 mm.

3. 3. The synchronous rotating electric machine according to claim 2, wherein the yoke has an angle θ in the range of 25.7°<θ≦36°, the number of the yokes being n, and n being any one of n=10, n=12, and n=14, and the magnet body is formed in a substantially rectangular parallelepiped shape.

4. 4. A synchronous rotating electric machine according to claim 3, wherein a protrusion is formed on the outer end of a side surface of said yoke, said protruding piece being formed along the circumferential direction and adapted to abut against the outer end surface of said magnet body.

5. 5. The synchronous rotating electric machine according to claim 4, wherein said rotor further comprises a holder made of a non-magnetic material through which said rotating shaft is inserted and fixed and which holds the base ends of said yokes.

6. 5. The synchronous rotating motor according to claim 4, characterized in that the rotor is configured to include a holder made of a non-magnetic material formed in a ring shape through which the rotating shaft is inserted and fixed, the holder having an outer periphery which holds the base ends of each of the yokes, the inner ends of the yokes being provided with engaging portions which protrude circumferentially to the left and right, and the outer periphery of the holder is formed with engaged portions which engage with the engaging portions when inserted from one or the other side of the holder perpendicular to the central axis.

7. 5. The synchronous rotating electric machine according to claim 4, wherein the rotor is configured to include a holder having a pair of plates made of a non-magnetic material, into which the rotating shaft is inserted and fixed, and which are attached to one and the other faces of each of the yokes perpendicular to the central axis, respectively, to hold a base end of each of the yokes, a first bolt insertion hole is formed in the base end of each of the yokes along the axial direction of the rotating shaft, a plurality of second bolt insertion holes corresponding to the first bolt insertion holes are formed in each of the plates of the holder, bolts made of a non-magnetic material are inserted into the second bolt insertion holes of the one plate, the first bolt insertion holes of each of the yokes and the second bolt insertion holes of the other plate, and nuts made of a non-magnetic material are screwed onto each bolt, so that each of the yokes is held by the pair of plates.

8. 8. The synchronous rotating electric machine according to claim 1, further comprising a radial position stator, the stator being provided with a plurality of stator coils arranged at predetermined intervals on a circumference centered on the rotation axis of the rotor and facing the outer circumferential surface of the rotor via an air gap.

9. 8. A synchronous rotating electric machine according to claim 1, further comprising an axial position stator having a plurality of stator coils arranged at predetermined intervals on a circumference centered on the rotation axis of the rotor and facing one and / or the other surface perpendicular to the central axis of the rotor via an air gap.

10. 8. The synchronous rotating electric machine according to claim 1, further comprising: a radial position stator having a plurality of stator coils arranged in a row at predetermined intervals on a circumference centered on the rotational axis of the rotor and facing an outer peripheral surface of the rotor via an air gap; and an axial position stator having a plurality of stator coils arranged in a row at predetermined intervals on a circumference centered on the rotational axis of the rotor and facing one side and / or the other side perpendicular to the central axis of the rotor via an air gap.

11. The stator is a radial position stator including a plurality of stator coils arranged at predetermined intervals on a circumference centered on a rotation axis of the rotor and facing an outer circumferential surface of the rotor via an air gap, and a plurality of teeth provided corresponding to the plurality of stator coils, respectively, around which the stator coils are wound, 8. A synchronous rotating electric machine as claimed in any one of claims 1 to 7, characterized in that the teeth of the radial position stator are configured to include a main body facing the outer peripheral surface of the rotor via an air gap, and a convex strip protruding from both ends of the main body in the central axial direction towards the central axis and having facing portions facing one side and the other side of the rotor via an air gap, and the stator coil is wound around the teeth with at least the facing portions of the convex strip exposed.

12. 12. The synchronous rotating electric machine according to claim 11, further comprising an insulating member interposed between said main body and said ridges.

13. 13. The synchronous rotating electric machine according to claim 12, wherein a plurality of said rotor / stator pairs are arranged in line on the same rotating shaft.

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