Motor rotor and permanent magnet motor

Abstract

This motor rotor comprises a rotary shaft, a holding member, a wire-shaped magnet, a holding ring, and a cushioning material. The holding member is fixed to the rotary shaft, and an arrangement space is formed in a recessed shape on an outer surface of the holding member on the outside in the radial direction. The wire-shaped magnet is disposed in the arrangement space. The holding ring holds the wire-shaped magnet from the outside in the radial direction. The cushioning material is provided in a gap in the radial direction between the holding member and the wire-shaped magnet and / or between the wire-shaped magnet and the holding ring.

Description

Motor rotor and permanent magnet motor

[0001] This application claims priority to Japanese Patent Application No. 2024-090605, filed on June 4, 2024, with the Japan Patent Office, the contents of which are incorporated herein by reference.

[0002] Permanent magnet motors are known that have rotors that use permanent magnets. To reduce eddy current loss, the motor rotors of these permanent magnet motors often use multiple bulk magnets. However, motor rotors that use multiple bulk magnets require a large number of assembly steps and are difficult to adjust for rotational balance.

[0003] One effective way to solve these problems is to use wire magnets instead of multiple bulk magnets. Wire magnets can be produced by compressing and molding magnetic powder into a jacket made of a non-magnetic material and then magnetizing it, or by sintering the magnetic powder. Wire magnets have small eddy current paths, making them suitable for suppressing eddy current loss, and by reducing the number of parts, they are advantageous for reducing the assembly labor required for motor rotors. Wire magnets can also easily be configured in a Halbach array, which can achieve high efficiency by concentrating the magnetic field on one side.

[0004] When a motor rotor is constructed using wire magnets, the wire magnets can be attached by being wound around the rotating shaft in the circumferential direction, but in a motor rotor having such a configuration, the wire magnets must be stably fixed to the rotating shaft so that they do not come off the rotating shaft due to centrifugal force acting during rotation. Patent Document 1 discloses an example of a motor rotor that does not use wire magnets, but has a stably fixed structure by applying a compressive force along the axial direction to a magnet attached to the rotating shaft.

[0005] Japanese Patent Application Laid-Open No. 2007-202371

[0006] In the above-mentioned Patent Document 1, a compressive force is applied along the axial direction to the magnet attached to the rotating shaft to stabilize the fixing structure. However, because the centrifugal force acting on the magnet during rotational driving acts along the radial direction, such a compressive force along the axial direction cannot effectively resist the centrifugal force. Therefore, in order to ensure sufficient stability, it is necessary to increase the compressive force acting on the magnet, which tends to make the fixing structure for the magnet to the rotating shaft unnecessarily large, which may increase manufacturing costs.

[0007] Another possible configuration for fixing a wire magnet to a rotating shaft is to place a cylindrical retaining ring radially outward of the wire magnet attached to the rotating shaft, and fix the wire magnet to the rotating shaft using the pressing load applied by the retaining ring. In this case, since the wire magnet is prone to large dimensional variations due to its shape characteristics, the pressing load applied by the retaining ring is unlikely to be uniform, which could result in excessive radial gaps between the wire magnet and the rotating shaft or between the wire magnet and the retaining ring, or the wire magnet could be damaged by the excessive pressing load.

[0008] At least one embodiment of the present disclosure has been made in consideration of the above circumstances, and aims to provide a motor rotor and a permanent magnet motor that can realize, at low cost, a configuration for stably fixing a wire-shaped magnet to a rotating shaft during rotational driving.

[0009] In order to solve the above problem, a motor rotor according to at least one embodiment of the present disclosure comprises: a rotating shaft; a retaining member fixed to the rotating shaft and having a recessed arrangement space formed on its radially outer surface; at least one wire-shaped magnet arranged in the arrangement space; a retaining ring for holding the at least one wire-shaped magnet from the radially outer side; and a buffer material provided in a radial gap at least either between the retaining member and the at least one wire-shaped magnet or between the at least one wire-shaped magnet and the retaining ring.

[0010] In order to solve the above problems, a permanent magnet motor according to at least one embodiment of the present disclosure includes a motor rotor according to at least one embodiment of the present disclosure.

[0011] According to at least one embodiment of the present disclosure, it is possible to provide a motor rotor and a permanent magnet motor that can realize, at low cost, a configuration for stably fixing a wire magnet to a rotating shaft during rotational driving.

[0012] Fig. 1 is a cross-sectional view taken along the axial direction of a motor rotor according to an embodiment. Fig. 2 is another example of the cross-sectional shape of the wire-shaped magnet of Fig. 1. Fig. 3 is another example of the cross-sectional shape of the wire-shaped magnet of Fig. 1. Fig. 4 is another example of the cross-sectional shape of the wire-shaped magnet of Fig. 1. Fig. 5 is a first modified example of Fig. 1. Fig. 6 is a second modified example of Fig. 1. Fig. 7 is a third modified example of Fig. 1. Fig. 8 is a fourth modified example of Fig. 1. Fig. 9 is a fifth modified example of Fig. 1.

[0013] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the configurations described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0014] FIG. 1 is a cross-sectional view taken along the axial direction of a motor rotor 1 according to one embodiment, and FIG. 2 is a cross-sectional view of the motor rotor 1 taken along line AA of FIG.

[0015] The motor rotor 1 is a rotor used in an inner rotor type permanent magnet motor, in which the motor rotor is placed inside the stator. In a permanent magnet motor, a permanent magnet is used in the motor rotor 1, and a secondary current does not flow through the motor rotor 1. This eliminates rotation loss, resulting in energy savings and excellent efficiency.

[0016] The motor rotor 1 includes a rotating shaft 2 , a holding member 4 , a wire-shaped magnet 6 , and a holding ring 8 .

[0017] The rotating shaft 2 is a shaft that can rotate when the permanent magnet motor is driven, and extends along the axial direction. The rotating shaft 2 has a substantially constant radius d1 and is rotatably supported by a bearing (not shown).

[0018] A holding member 4 for holding a wire-shaped magnet 6 is fixed to the outer surface of the rotating shaft 2. The holding member 4 is attached to the central portion of the rotating shaft 2 excluding both end sides, has a substantially constant diameter d2 (>d1), and has an arrangement space 4a formed on its radially outer side for attaching the wire-shaped magnet 6. This arrangement space 4a is formed in a concave shape on the outer radial surface of the holding member 4 so that the holding member 4 surrounds the wire-shaped magnet 6 on all sides except the radially outer side. The arrangement space 4a is configured to be able to accommodate the entire wire-shaped magnet 6 so that the wire-shaped magnet 6 arranged inside does not protrude radially outward beyond the holding member 4. The shape of the arrangement space 4a is configured to correspond to the shape of the wire-shaped magnet 6, and its specific shape is not particularly limited.

[0019] The wire-shaped magnet 6 is a permanent magnet with an elongated shape, and is arranged so as to be wound circumferentially in the arrangement space 4a provided in the holding member 4. In this embodiment, the wire-shaped magnet 6 has a length in the longitudinal direction that is sufficiently larger than the circumferential length of the arrangement space 4a, and is wound spirally around the arrangement space 4a. The wire-shaped magnets 6 wound around the arrangement space 4a are arranged closely so that adjacent side surfaces along the axial direction are in contact with each other. The wire-shaped magnet 6 with an elongated shape has a small eddy current path, making it suitable for suppressing eddy current loss, and it is possible to easily realize a Halbach array that concentrates the magnetic field on one side and achieves high efficiency.

[0020] In this embodiment, as shown in Figure 1, the wire magnet 6 may be configured to include a jacket 6a and magnetic powder 6b housed within the jacket 6a. In this case, the jacket 6a is made of a non-magnetic material. The magnetic powder 6b is made by compressing magnetic powder, which is a powdered magnetic material, and is housed within the jacket 6a.

[0021] In the embodiment shown in FIG. 1 , the wire magnet 6 has a substantially square cross section perpendicular to the longitudinal direction, but other cross sections may be used. For example, as shown in FIG. 2A , a rectangular cross section allows the wire magnets 6 to be arranged without gaps, thereby favorably improving the performance of a permanent magnet motor incorporating the motor rotor 1. As shown in FIG. 2B , an elliptical cross section is easier to manufacture than a rectangular cross section and favorably reduces manufacturing costs. As shown in FIGS. 2C and 2D , a trapezoidal or parallelogram cross section has lower radial rigidity than a rectangular cross section. Therefore, deformation of the wire magnet 6 due to the pressing load applied thereto facilitates uniformity of the pressing load acting on the retaining ring 8. In this case, the structural strength may be lower than when the cross section is square, but this can be addressed by increasing the thickness of the buffer material 12 (described below) or by using a buffer material 12 with a low elastic modulus.

[0022] The retaining ring 8 is configured to hold the wire magnet 6 provided in the arrangement space 4a of the holding member 4 from the radially outer side. The retaining ring 8 is a substantially cylindrical member with an inner diameter corresponding to the outer diameter of the wire magnet 6 provided in the arrangement space 4a. The wire magnet 6 provided in the arrangement space 4a is placed inside the retaining ring 8 while being subjected to a pressing load by placing the retaining ring 8 on the radially outer side while being pressed radially inward. The pressing load applied to the wire magnet 6 at this time can be adjusted to fall within an appropriate tolerance range, as described below.

[0023] The rotating shaft 2 and the holding member 4, and the holding member 4 and the holding ring 8 are fixed together by interference fitting or shrink fitting, respectively.

[0024] A radial gap 14 filled with buffer material 12 is provided between the retaining ring 8 and the wire-shaped magnet 6 or between the wire-shaped magnet 6 and the rotating shaft 2. In this embodiment, a case where buffer material 12 is provided in the radial gap 14 between the wire-shaped magnet 6 and the rotating shaft 2 is exemplified, but buffer material 12 may also be provided in the radial gap between the retaining ring 8 and the wire-shaped magnet 6.

[0025] The buffer material 12 is made of a material with excellent cushioning properties (stretchability) and a lower modulus of elasticity than the surrounding components such as the rotating shaft 2, the wire magnet 6, and the retaining ring 8, and can be, for example, silicone rubber, urethane rubber, or a resin material. If the temperature of the motor rotor 1 rises, a material with a high heat resistance, such as silicone rubber, may be selected.

[0026] As mentioned above, a retaining ring 8 is installed radially outward of the wire magnet 6 to prevent the wire magnet 6 from separating from the retaining member 4 fixed to the rotating shaft 2 due to centrifugal force acting during rotation. This retaining ring 8 is assembled by pressing the wire magnet 6 radially inward with a buffer material 12 with excellent cushioning properties placed between the retaining member 4 and the wire magnet 6. The restoring force of the buffer material 12 presses and fixes the wire magnet 6 against the retaining ring 8. The buffer material 12 serves to absorb dimensional variations in the wire magnet 6. Without the buffer material 12, if the actual dimensions of the wire magnet 6 were larger than the design values, the wire magnet 6 would be pinched between the retaining ring 8 and the retaining member 4, resulting in an excessive pressing load and potentially damaging the wire magnet 6. Conversely, if the actual dimensions of the wire magnet 6 were smaller than the design values, a gap would be created between the wire magnet 6 and the retaining member 4, making it impossible to fix the wire magnet 6. Therefore, in this embodiment, by placing a deformable buffer material 12 between them, the dimensional variations of the wire-shaped magnet 6 can be absorbed and the wire-shaped magnet 6 can be fixed with an appropriate pressing load.

[0027] The buffer material 12 may be placed without any gaps in the radial gap 14, but there may be areas where there is no buffer material 12 partially.

[0028] As described above, a pressing load is applied to the wire magnets 6 provided in the motor rotor 1, and the motor rotor 1 may be provided with an adjustment mechanism 20 for adjusting such a pressing load.

[0029] Fig. 3 shows a first modified example of Fig. 1. The motor rotor 1A according to the first modified example has an adjustment mechanism 20 including a first adjustment member 22, a second adjustment member 24, and a third adjustment member 26.

[0030] The first adjustment member 22 is formed integrally with the aforementioned holding member 4 and fixed to the rotating shaft 2, and has an arrangement space 4a for arranging the wire-shaped magnet 6. As in the embodiment shown in Fig. 1 , the wire-shaped magnet 6 and buffer material 12 are arranged in the arrangement space 4a, but an insertion space 25 for inserting the second adjustment member 24 is additionally provided radially inward of the buffer material 12. A tapered surface 22a is provided radially inward of this additional insertion space 25 to correspond to the second adjustment member 24. This tapered surface 22a faces the buffer material 12 arranged adjacent to the wire-shaped magnet 6, and is configured so that the distance between this tapered surface 22a and the buffer material 12 gradually decreases from one side (the left side in Fig. 4 ) to the other side (the right side in Fig. 3 ) along the axial direction (i.e., it is configured so that it becomes narrower toward the back when viewed from the opening side).

[0031] The second adjustment member 24 is a member that can be inserted into the insertion space 25, and has a shape that corresponds to the insertion space 25. Specifically, the radially outer surface of the second adjustment member 24 is approximately parallel (axially) to the radially inner side of the buffer material 12, and the radially inner surface is inclined approximately parallel to the tapered surface 22 a of the first adjustment member 22.

[0032] The third adjustment member 26 is configured to adjust the insertion amount of the second adjustment member 24 into the insertion space 25. Specifically, the third adjustment member 26 is a bolt member that attaches the second adjustment member 24 to the first adjustment member 22, and one end side is fixed by a nut 27, while the other end side is engaged with a threaded hole 28 formed in the first adjustment member 22. By rotating the third adjustment member 26, the insertion amount into the threaded hole 28 changes, and accordingly, the insertion amount of the second adjustment member 24 into the insertion space 25 can be adjusted.

[0033] For example, when the third adjustment member 26, which is a bolt member, is tightened, the second adjustment member 24 is inserted into the back of the insertion space 25, and the wire magnet 6 is fixed in a state where it is pressed against the retaining ring 8. At this time, the pressing load acting on the wire magnet 6 increases, and the wire magnet 6 is firmly fixed, but if the pressing load becomes excessive, there is a risk of damaging the wire magnet 6. On the other hand, when the third adjustment member 26, which is a bolt member, is loosened, the second adjustment member 24 is pulled out toward the front of the insertion space 25, and the pressing load is reduced. In this way, the adjustment mechanism 20 can easily adjust the pressing load acting on the wire magnet 6 to an appropriate allowable range.

[0034] In this embodiment, as described above, by interposing the buffer material 12 between the wire-shaped magnet 6 and the second adjustment member 24, the buffer material 12 functions as a cushion when adjusting such a pressing load, thereby preventing an excessive pressing load from acting on the wire-shaped magnet 6. Furthermore, although the wire-shaped magnet 6 is prone to large dimensional variations, the deformation of the buffer material 12 can absorb the dimensional variations of the wire-shaped magnet 6 and make the pressing load acting on the wire-shaped magnet 6 uniform.

[0035] Furthermore, in the adjustment mechanism 20 configured as described above, the pressing load can be adjusted appropriately by adjusting the tightening torque or tightening rotation angle of the third adjustment member 26. However, there is a risk that the tightening torque and tightening rotation angle will also vary to a certain extent, which will also cause variations in the pressing load on the wire magnet 6. In this embodiment, the use of the buffer material 12 also has the effect of substantially reducing such variations in the tightening torque and tightening rotation angle.

[0036] FIG. 4 shows a second modified example of the motor rotor 1B shown in FIG. 1 . The motor rotor 1B according to the second modified example differs in that the first adjustment member 22 is provided as a separate member from the holding member 4 fixed to the rotating shaft 2. As described above, the holding member 4 has a recessed arrangement space 4a for arranging the wire magnet 6 and the buffer material 12, and the adjustment mechanism 20 (the first adjustment member 22, the second adjustment member 24, and the third adjustment member 26) can be accommodated inside the arrangement space 4a. The arrangement space 4a is relatively wide enough to ensure sufficient space for accommodating the adjustment mechanism 20, and the first adjustment member 22 is arranged radially inward of the wire magnet 6 and the buffer material 12. As described above, the first adjustment member 22 is arranged so as to form an insertion space 25 between the first adjustment member 22 and the buffer material 12, into which the second adjustment member 24 can be inserted.

[0037] In this manner, in this modified example, the adjustment mechanism 20 is configured to be able to be accommodated inside the arrangement space 4a of the holding member 4 fixed to the rotating shaft 2, and therefore the above configuration can be easily realized, for example, by using the holding member 4 as an attachment and adopting an adjustment mechanism 20 that is sold as an existing product on the market.

[0038] 5 shows a third modified example of the motor rotor 1C shown in FIG. The adjustment mechanism 20 of the motor rotor 1C according to the third modified example further includes an end plate 4c disposed between a wall portion 4b of the holding member 4 (first adjustment member 22) perpendicular to the axial direction and an end plate 4c that sandwiches the wire magnet 6 held by the holding member 4, and a fourth adjustment member 30 for adjusting the axial distance L between the wall portion 4b and the end plate 4c. The fourth adjustment member 30 is a bolt member that extends axially, penetrates the end plate 4c, and has its tip engaged with a threaded hole 32 provided in the wall portion 4b. By adjusting the degree of tightening of the fourth adjustment member 30, which is a bolt member, the insertion amount of the tip into the threaded hole 32 changes, thereby varying the axial distance L.

[0039] Furthermore, the aforementioned buffer material 12 is disposed between the wall portion 4b and the end plate 4c. This buffer material 12 is disposed so as to be sandwiched between the wall portion 4b and the end plate 4c, and is subjected to a compressive force according to the axial distance L. For example, if the axial distance L is adjusted to be small, the buffer material 12 deforms so as to expand in the radial direction as the compressive force increases, thereby increasing the pressing load on the wire-shaped magnet 6 (Poisson effect). On the other hand, if the axial distance L is adjusted to be large, the pressing load on the buffer material 12 against the wire-shaped magnet 6 weakens as the compressive force decreases.

[0040] In this way, the motor rotor 1C allows the pressing load on the wire magnet 6 to be adjusted with a simple configuration.

[0041] 6 shows a fourth modified example of the motor rotor 1D shown in FIG. Compared to the motor rotor 1C according to the third modified example, the motor rotor 1D according to the fourth modified example further includes a fifth adjustment member 34. The fifth adjustment member 34 is disposed radially inward of the buffer material 12 so as to ensure a separation space 36 between the buffer material 12 and the rotating shaft 2.

[0042] For example, the fifth adjustment member 34 is a cylindrical member attached around the rotating shaft 2, and has an isolation space 36 secured inside it. By providing the fifth adjustment member 34 in this manner, the volume of the buffer material 12 can be reduced, and therefore, when the fourth adjustment member 30, which is a bolt member, is tightened, a pressing load can be efficiently applied to the wire-shaped magnet 6.

[0043] In the above-described embodiments, examples have been given in which the wire magnet 6 is composed of a jacket 6a and magnetic powder 6b, but the wire magnet 6 may also be a sintered magnet without a jacket 6a. In this case, the strength of the wire magnet 6 will be reduced by the absence of a jacket, but the pressing load received by the wire magnet 6 can be suitably adjusted to an appropriate allowable range using the buffer material 12 and adjustment mechanism 20 described above. By using a wire magnet 6 made of a sintered magnet without a jacket 6a in this way, a strong magnetic force can be obtained, making it possible to achieve excellent motor performance.

[0044] Furthermore, in order to prevent the pressing load acting on the wire magnet 6 from becoming excessive, it is necessary to precisely control the pressing load so that an excessive pressing load does not act. As a means for doing so, for example, the thickness of the buffer material 12 may be increased. Furthermore, bolt members with small diameters and thread pitches may be used as the third adjustment member 26 and the fourth adjustment member 30, which are bolt members, so that the change in pressing load relative to the amount of rotation of the fourth adjustment member 30, which is a bolt member, is small. Furthermore, buffer material 12 with a small Poisson's ratio may be used so that the change in pressing load relative to the amount of rotation of the fourth adjustment member 30, which is a bolt member, is small.

[0045] Figure 7 is a cross-sectional view perpendicular to the axial direction of the fifth modified example of Figure 1. The motor rotor 1E according to the fifth modified example includes a first wire-shaped magnet 6-1 and a second wire-shaped magnet 6-2 as the wire-shaped magnets 6. The second wire-shaped magnet 6-2 is disposed radially outward of the first wire-shaped magnet 6-1, so that the motor rotor 1E has a plurality of wire-shaped magnets 6 arranged in multiple layers along the radial direction.

[0046] In this case, the aforementioned buffer material 12 is provided at least between the first wire-shaped magnet 6-1 and the second wire-shaped magnet 6-2, or between the first wire-shaped magnet 6-1 and the rotating shaft 2. In the embodiment shown in FIG. 7, buffer material 12 is provided both between the first wire-shaped magnet 6-1 and the second wire-shaped magnet 6-2, and between the first wire-shaped magnet 6-1 and the rotating shaft 2. As mentioned above, the wire-shaped magnets 6 have large dimensional variations, so arranging the wire-shaped magnets 6 in multiple layers like this tends to further increase the dimensional variations. Therefore, by providing buffer material 12 between each layer of wire-shaped magnets 6 or between the wire-shaped magnet 6 and the rotating shaft 2, the effects of these dimensional variations can be suitably absorbed.

[0047] Furthermore, even if the buffer material 12 is provided only between the first wire-shaped magnet 6-1 and the second wire-shaped magnet 6-2, or only between the first wire-shaped magnet 6-1 and the rotating shaft 2, the effects of dimensional variations can be effectively absorbed by setting the thickness of the buffer material 12 to be large.

[0048] The first wire-shaped magnet 6-1 and the second wire-shaped magnet 6-2 may be attached by being wound around them as in the above-described embodiments, but in Fig. 7 they are configured by axially arranging a plurality of ring-shaped members 40, each extending in the circumferential direction of the rotating shaft 2. In this case, the openings 42 of the ring-shaped members 40 may be located at different circumferential positions between the first wire-shaped magnet 6-1 and the second wire-shaped magnet 6-2 (positions that are 180 degrees apart from each other in Fig. 7).

[0049] In each of the above embodiments, a single wire magnet 6 is wound spirally around the rotating shaft 2 over multiple revolutions. In this case, the surface of the end plate 4c facing the wire magnet 6 is configured to fit by having a shape that corresponds to the end of the wire magnet 6. The wire magnet 6 may also be configured by continuously winding multiple wire magnets 6.

[0050] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0051] The contents described in each of the above embodiments can be understood, for example, as follows.

[0052] (1) A motor rotor according to one embodiment comprises: a rotating shaft; a retaining member fixed to the rotating shaft and having a recessed arrangement space formed on its radially outer surface; at least one wire-shaped magnet arranged in the arrangement space; a retaining ring for holding the at least one wire-shaped magnet from the radially outer side; and a buffer material provided in a radial gap at least either between the retaining member and the at least one wire-shaped magnet or between the at least one wire-shaped magnet and the retaining ring.

[0053] According to the above aspect (1), a buffer material is provided in the radial gap between the holding member and the wire magnet or between the wire magnet and the holding ring. The buffer material is made of a material, such as silicone rubber, urethane rubber, or a resin material, that has a lower elastic modulus than surrounding components such as the rotating shaft, and functions as a so-called cushioning material. A holding ring is installed radially outward of the wire magnet to prevent the wire magnet from separating from the rotating shaft due to centrifugal force acting during rotation. With the buffer material thus arranged, the holding ring is assembled by pressing the wire magnet radially inward. The wire magnet is fixed while receiving a pressing load from the holding ring, which depends on the dimensional variation of the wire magnet. In this aspect, by providing the buffer material in the radial gap, the restoring force of the buffer material absorbs dimensional variation of the wire magnet, allowing the wire magnet to be fixed with an appropriate pressing load.

[0054] (2) In another aspect, in the aspect (1), the buffer material is provided in the radial gap between the holding member and the at least one wire magnet.

[0055] According to the above aspect (2), the buffer material is provided radially inside the wire-shaped magnet, so that the pressing load that the wire-shaped magnet receives during rotational driving can be appropriately received by the buffer material.

[0056] (3) In another aspect, in the aspect (1) or (2), an adjustment mechanism is provided for adjusting the pressing load acting on the at least one wire magnet.

[0057] According to the above aspect (3), the pressing load acting on the wire magnet can be adjusted by the adjustment mechanism to fall within an appropriate allowable range.

[0058] (4) In another aspect, in the aspect (3) above, the adjustment mechanism includes: a first adjustment member having a tapered surface facing the cushioning material from the radially inner side; a second adjustment member that can be inserted into an insertion space between the cushioning material and the tapered surface; and a third adjustment member for adjusting the insertion amount of the second adjustment member into the insertion space.

[0059] According to the above aspect (4), the pressing load acting on the wire-shaped magnet can be easily increased or decreased by adjusting the insertion amount of the second adjustment member into the insertion space provided between the tapered surface of the first adjustment member and the cushioning material.

[0060] (5) In another aspect, in the aspect (4), the first adjustment member is configured integrally with the holding member.

[0061] According to the above aspect (5), by configuring the first adjustment member of the adjustment mechanism integrally with the holding member, the number of components can be reduced and the above configuration can be realized more simply.

[0062] (6) In another aspect, in the aspect (3), the adjustment mechanism is fixed to the rotation shaft via the holding member.

[0063] According to the above aspect (6), the adjustment mechanism is fixed to the fixed shaft via the holding member, which makes it possible to easily realize a configuration that allows adjustment of the pressing load, for example, by using an adjustment mechanism having an existing configuration, such as a commercially available product.

[0064] (7) In another aspect, in the aspect (3) above, the adjustment mechanism further includes a fourth adjustment member for adjusting the axial distance between a wall portion of the holding member that is perpendicular to the rotation axis and an end plate that is provided on the opposite side of the wall portion from the buffer material.

[0065] According to the above aspect (7), by adjusting the axial distance between the wall portion and the end plate with the fourth adjustment member, the degree of compression of the buffer material between them can be changed. This allows the thickness of the buffer material to be compressed to be changed, thereby allowing the pressing load acting on the wire-shaped magnet adjacent to the buffer material to be adjusted with a simple configuration.

[0066] (8) In another aspect, in the aspect (7) above, the adjustment mechanism further includes a fifth adjustment member arranged radially inward of the buffer material so as to ensure an isolation space between the buffer material and the rotating shaft.

[0067] According to the above aspect (8), by using the fifth adjustment member to ensure a separating space between the buffer material and the rotating shaft, the pressing load acting on the wire-shaped magnet can be suitably changed by adjusting the axial distance between the pair of end plates as described above.

[0068] (9) In another aspect, in any one of the above aspects (1) to (8), the at least one wire magnet includes: a jacket made of a non-magnetic material; and a magnetic powder body contained in the jacket and including compression-molded magnetic powder.

[0069] According to the above aspect (9), the wire magnet is configured by housing a magnetic powder body in which magnetic powder is compressed and molded within a jacket. Because wire magnets with this configuration have lower strength than sintered magnets, large dimensional variations in the wire magnets can increase the pressing load from the retaining ring, potentially causing crushing. In the motor rotor of this aspect, by providing a buffer material in the radial gap as described above, even when wire magnets with this configuration are used, the buffer material can absorb dimensional variations in the wire magnets, thereby suitably equalizing the pressing load acting on the wire magnets.

[0070] (10) In another aspect, in any one of the above (1) to (8), the at least one wire magnet is a sintered magnet.

[0071] According to the above aspect (10), the wire magnet is made of a sintered magnet formed by sintering magnetic powder. A wire magnet made of such a sintered magnet can obtain a strong magnetic force, and can realize excellent motor performance.

[0072] (11) In another aspect, in any one of the above aspects (1) to (10), the at least one wire magnet has a cross section perpendicular to the axial direction that is either rectangular, elliptical, trapezoidal, or parallelogram-shaped.

[0073] According to the above aspect (11), the cross-sectional shape of the wire magnet can be various shapes, such as a rectangle, an ellipse, a trapezoid, or a parallelogram. For example, if the cross-sectional shape is rectangular (including a square), the wire magnets can be arranged tightly on the rotation shaft, improving the performance of the permanent magnet motor equipped with the motor rotor. Furthermore, if the cross-sectional shape is elliptical (including circular), it is easier to manufacture than a rectangle and can more effectively reduce manufacturing costs. Furthermore, if the cross-sectional shape is trapezoidal or parallelogram, the radial rigidity is lower than that of a rectangle, so dimensional variations in the wire magnet can be absorbed and the pressing load received by the wire magnet can be more effectively uniformed.

[0074] (12) In another aspect, in any one of the above aspects (1) to (11), the at least one wire-shaped magnet includes a first wire-shaped magnet and a second wire-shaped magnet arranged radially outward from the first wire-shaped magnet, and the buffer material is arranged at least either between the first wire-shaped magnet and the second wire-shaped magnet or between the first wire-shaped magnet and the rotation shaft.

[0075] According to the above aspect (12), the wire magnets are arranged in multiple layers in the radial direction. In this configuration, arranging the wire magnets in multiple layers tends to result in large dimensional variations, but by providing buffer material between each layer of wire magnets or between the wire magnets and the rotating shaft, the effects of these dimensional variations can be suitably absorbed.

[0076] (13) In another aspect, in any one of the above aspects (1) to (12), the at least one wire magnet is wound spirally around the rotation axis.

[0077] According to the above aspect (13), in a motor rotor in which a wire-shaped magnet is wound spirally around a rotating shaft and fixed thereto, by providing a buffer material in the radial gap, the pressing load received by the wire-shaped magnet can be suitably uniformed.

[0078] (14) A permanent magnet motor according to one aspect includes the motor rotor according to any one of the above aspects (1) to (13).

[0079] According to the above aspect (14), by having the above-mentioned motor rotor, a permanent magnet motor can be obtained that can realize at low cost a structure for stably fixing the wire-shaped magnet to the rotating shaft during rotational driving.

[0080] DESCRIPTION OF SYMBOLS 1, 1A to 1E Motor rotor 2 Rotating shaft 4 Holding member 4a Arrangement space 4b Wall portion 4c End plate 6 Wire magnet 6a Jacket 6b Magnetic powder 6-1 First wire magnet 6-2 Second wire magnet 8 Holding ring 12 Cushioning material 14 Radial gap 20 Adjustment mechanism 22 First adjustment member 22a Tapered surface 24 Second adjustment member 25 Insertion space 26 Third adjustment member 27 Nut 28 Screw hole 30 Fourth adjustment member 32 Screw hole 34 Fifth adjustment member 36 Separation space 40 Ring-shaped member 42 Opening

Claims

1. A motor rotor comprising: a rotating shaft; a retaining member fixed to the rotating shaft and having a recessed arrangement space formed on its radially outer surface; at least one wire-shaped magnet arranged in the arrangement space; a retaining ring for retaining the at least one wire-shaped magnet from the radially outer side; and a buffer material provided in a radial gap at least either between the retaining member and the at least one wire-shaped magnet or between the at least one wire-shaped magnet and the retaining ring.

2. The motor rotor of claim 1, wherein the buffer material is provided in the radial gap between the retaining member and the at least one wire magnet.

3. The motor rotor according to claim 1 or 2, further comprising an adjustment mechanism for adjusting the pressing load acting on said at least one wire-shaped magnet.

4. A motor rotor as described in claim 3, wherein the adjustment mechanism includes: a first adjustment member having a tapered surface facing the cushioning material from the radially inner side; a second adjustment member insertable into an insertion space between the cushioning material and the tapered surface; and a third adjustment member for adjusting the insertion amount of the second adjustment member into the insertion space.

5. The motor rotor according to claim 4, wherein said first adjusting member is integrally formed with said holding member.

6. The motor rotor according to claim 3, wherein the adjustment mechanism is fixed to the rotary shaft via the holding member.

7. A motor rotor as described in claim 3, wherein the adjustment mechanism further comprises a fourth adjustment member for adjusting the axial distance between a wall portion of the holding member that is perpendicular to the rotation axis and an end plate provided on the opposite side of the wall portion from the buffer material.

8. A motor rotor as described in claim 7, wherein the adjustment mechanism further comprises a fifth adjustment member arranged radially inward of the buffer material so as to ensure an isolation space between the buffer material and the rotating shaft.

9. The motor rotor according to claim 1 or 2, wherein the at least one wire-shaped magnet comprises: a jacket made of a non-magnetic material; and a magnetic powder body that is housed in the jacket and includes compression-molded magnetic powder.

10. The motor rotor according to claim 1 or 2, wherein said at least one wire magnet is a sintered magnet.

11. A motor rotor according to claim 1 or 2, wherein the at least one wire-shaped magnet has a cross section perpendicular to the axial direction that is either rectangular, elliptical, trapezoidal or parallelogrammatic.

12. A motor rotor as described in claim 1 or 2, wherein the at least one wire-shaped magnet includes a first wire-shaped magnet and a second wire-shaped magnet arranged radially outward from the first wire-shaped magnet, and the buffer material is arranged at least either between the first wire-shaped magnet and the second wire-shaped magnet or between the first wire-shaped magnet and the rotating shaft.

13. The motor rotor according to claim 1 or 2, wherein the at least one wire magnet is wound helically around the rotational shaft.

14. A permanent magnet motor having a motor rotor according to claim 1 or 2.

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