Magnet, electric motor and manufacturing method of magnet

Abstract

To accurately set orientation directions of a main pole and an interpole to realize a magnet which allows easy manufacture of a permanent magnet unit of a magnetic flux concentration type with high magnetic flux density.SOLUTION: A magnet 22 is constituted by comprising a permanent magnet unit 22a consisting of: a main pole 221 which is constituted by laminating permanent magnet sheets 221a with approximately the same thickness dimensions in a thickness direction; and an interpole 222 which is constituted to concentrate magnetic fluxes on the main pole 221 by laminating permanent magnet sheets 222a with approximately the same thickness dimensions in the thickness direction to be arranged at an adjacent position of the main pole 221 by differentiating an orientation direction from that of the main pole 221.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a magnet having a high magnetic flux density as a magnetic flux concentrating type magnet such as a Halbach array, a motor, and a method for manufacturing a magnet.

Background Art

[0002] Conventionally, as a magnet with increased magnetic flux density, a Halbach array magnet applied to the rotor of a permanent magnet motor is known (for example, Patent Document 1).

[0003] This array, unlike a parallel-aligned magnet, arranges permanent magnets with different orientation directions so that magnetic flux concentrates at the center of the pole, thereby increasing the magnetic flux density on the gap surface between the rotor and the stator.

[0004] Conventionally, in order to manufacture a magnet with this structure, a lump of permanent magnet with a predetermined dimension and a predetermined orientation is made for each main pole oriented in the radial direction and each auxiliary pole oriented in the main pole direction, and these main poles and auxiliary poles are assembled by adhering them to the outer periphery of a rotor core constituting a rotor, for example, in the case of an inner rotor. In the case of an outer rotor, these main poles and auxiliary poles are assembled by adhering them to the inner periphery of the rotor core.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when the main poles and the auxiliary poles are each composed of a lump of permanent magnet, there is a problem that it is difficult to uniformly align the orientation directions of the entire main poles and the entire auxiliary poles throughout the interior.

[0007] In addition, if the main pole and secondary pole are composed of blocks of permanent magnets, large eddy currents will flow, which hinders the increase in motor power density.

[0008] Furthermore, since a permanent magnet block must be prepared for each permanent magnet and cut to the required dimensions as needed to manufacture each permanent magnet, there is a problem with low productivity.

[0009] This invention has been made in view of these problems, and aims to realize a magnet, an electric motor, and a method for manufacturing a magnet that enable the precise setting of the orientation direction of the main pole and secondary pole for magnetic flux concentration, and the easy manufacture of a permanent magnet unit with high magnetic flux density. [Means for solving the problem]

[0010] To achieve this objective, the present invention employs the following means.

[0011] In other words, the magnet of the present invention is characterized by comprising a permanent magnet unit comprising a main pole formed by stacking permanent magnet sheets of substantially the same thickness in the thickness direction, and a secondary pole formed by stacking permanent magnet sheets of substantially the same thickness in the thickness direction and arranging them adjacent to the main pole with a different orientation direction from the main pole, thereby concentrating magnetic flux on the main pole.

[0012] Here, the dimension in the stacking direction of a permanent magnet sheet is simply referred to as the thickness dimension, and the stacking direction as the thickness direction. Therefore, the thickness direction here is not necessarily uniquely related to the geometric thickness direction or magnetization direction of the main pole or complementary pole.

[0013] Thus, by using a laminated structure of permanent magnet sheets for the main poles and co-poles, the orientation direction can be set with greater precision compared to when the main poles and co-poles are solid blocks of permanent magnets. This makes it possible to easily and appropriately manufacture a magnetic flux-concentrated permanent magnet unit with high magnetic flux density. Moreover, since the surface area that generates eddy current losses is reduced, eddy current losses are decreased, and this reduction in temperature enables the realization of high magnetic flux density, allowing for even smaller and more powerful motors and other applications.

[0014] It is preferable that the orientation direction of the permanent magnet sheet constituting the main pole and the permanent magnet sheet constituting the co-pole coincide. Furthermore, it is preferable that the permanent magnet sheet constituting the main pole and the permanent magnet sheet constituting the secondary pole have the same thickness.

[0015] This method helps to suppress variations in the magnetic properties of the main and secondary poles due to processing.

[0016] Preferably, at least one of the main pole or the secondary pole is further divided in a direction perpendicular to the thickness direction.

[0017] By dividing the material in the direction perpendicular to the thickness direction, the surface that generates eddy current losses can be further reduced.

[0018] Preferably, the permanent magnet units are configured one pole at a time and arranged along the thrust generation direction, and a portion of the core, which is the thrust generation element, has a magnet holding portion consisting of a wall-like portion extending between the permanent magnet units in a direction perpendicular to the thrust generation direction, and an enlarged portion extending from the end of this wall-like portion in a direction overlapping with the corner on the end side of the permanent magnet unit.

[0019] The structure, which holds the permanent magnet unit with an enlarged section, makes it possible to hold the permanent magnet using only the motor's magnetic circuit components. By providing a notch in the corner of the complementary pole of the permanent magnet unit to accommodate the enlarged section, it is possible to avoid increasing the gap length between the stator and the movable section when applied to a motor, etc. Furthermore, when the corner is held in place by the enlarged section, if a flux-concentrating magnet such as a Halbach array magnet is used compared to a parallel-oriented magnet, the leakage of magnetic flux through the enlarged section will be reduced, thus avoiding a decrease in magnetic flux density.

[0020] By equipping the rotor of an electric motor with the above-described magnets, a compact, lightweight, high-torque, and highly efficient multi-pole surface magnet type rotor can be appropriately constructed.

[0021] In addition, the method for manufacturing a magnet according to the present invention forms a main pole by cutting out from a predetermined direction with respect to a laminate formed by laminating permanent magnet sheets, and laminates a permanent magnet sheet having the same orientation as the permanent magnet sheet of the main pole. It is characterized in that a compensating pole is formed whose orientation direction is different from that of the main pole when assembled at an adjacent position to the main pole by cutting out from a different direction with respect to the laminate.

[0022] By doing so, it is possible to easily manufacture a main pole and a compensating pole having different orientation directions with small eddy current loss in the same manufacturing process.

Effect of the Invention

[0023] According to the present invention described above, it is possible to provide a magnet, an electric motor, and a method for manufacturing a magnet that can accurately set the orientation directions of the main pole and the compensating pole and easily manufacture a flux concentration type permanent magnet unit having a high magnetic flux density.

Brief Description of the Drawings

[0024] [Figure 1] Partial enlarged cross-sectional view of a motor, which is an electric motor provided with a magnet according to an embodiment of the present invention. [Figure 2] Perspective view showing a permanent magnet unit constituting the magnet of FIG. 1. [Figure 3] Diagram for explaining eddy currents generated in the permanent magnet unit. [Figure 4] Diagram showing a method for manufacturing the permanent magnet unit. [Figure 5] Diagram showing a method for manufacturing a magnet in the embodiment. [Figure 6] Diagram showing a method for manufacturing the magnet. [Figure 7] Diagram showing the flow of magnetic flux generated in the magnet together with a comparative example. [Figure 8] Diagram showing a modified example of the present invention. [Figure 9] Diagram showing another modified example of the present invention. [Figure 10] Diagram showing still another modified example of the present invention. [Figure 11]A figure showing a modified example of the present invention other than those described above. [Figure 12] A figure showing further modifications of the present invention other than those described above. [Modes for carrying out the invention]

[0025] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0026] Figure 1 shows an example in which the magnet of the present invention is applied to a motor M, which is an electric motor.

[0027] As shown in Figure 1(a), the motor M is an inner rotor type rotating electric machine, in which a rotor 2, which is a movable element, is attached to a shaft 1 so as to be able to rotate as a whole, and a stator 3 is arranged around the outer circumference of the rotor 2.

[0028] The stator 3 comprises a stator core 31 configured in a substantially cylindrical shape, a plurality of teeth 32 integrally formed inward from equiangular positions on the stator core 31, and a coil 33 wound around each tooth 32. A power supply device (not shown) is connected to the coil 33 and is configured to generate a rotating magnetic field for rotating the rotor 2 by supplying power.

[0029] The rotor 2 is positioned on the inner circumference side of the stator 3 with a predetermined gap between them. The rotor 2 comprises a substantially cylindrical rotor core 21 and permanent magnets 22 arranged on the outer circumference along the rotor core 21.

[0030] The permanent magnet 22 is constructed in a ring shape by arranging multiple permanent magnet units 22a, each consisting of a main pole 221 and a co-pole 222, in the thrust generation direction, i.e., the circumferential direction of the rotor core 21, in order of the number of poles. As shown in Figure 1(b), the permanent magnet units 22a constitute a magnetic flux-concentrating magnet such as a Halbach array. The main pole 221 is positioned so that its orientation direction, indicated by the thick arrow, is perpendicular to the thrust generation direction, which is the radial direction (R direction). The co-pole 222 is positioned on both sides of the main pole 221, and its orientation direction, indicated by the thick arrow, is directed toward the main pole 221, i.e., in a direction that makes a predetermined angle (±α: α is preferably acute) with respect to the radial direction. The orientation direction refers to the direction in which magnetization is easily achieved. Permanent magnets are magnetized along the orientation direction. In Figure 1 and other figures, the orientation direction is indicated by arrows at both ends, and the magnetization direction is indicated by arrows at one or the other end.

[0031] In this embodiment, the motor M has one permanent magnet unit 22a consisting of one main pole and two auxiliary poles, and the number of permanent magnet units 22a is used to determine the number of poles of the motor M, thus forming a multi-pole surface magnet type rotor 2.

[0032] Furthermore, this permanent magnet arrangement makes it easier to concentrate the magnetic flux on the main pole 221 compared to parallel-oriented magnets, resulting in a magnetic flux-concentrating magnet 22 similar to a Halbach arrangement.

[0033] While permanent magnet motors can increase magnetic flux density, eddy currents increase proportionally to the square of both the magnetic flux due to armature reaction and the excitation frequency. Therefore, when increasing the excitation frequency or increasing the current to increase magnetic flux in order to increase the power density of the motor M, the increase in eddy currents becomes a problem. An increase in eddy current losses leads to overheating of the magnet 22 and a decrease in motor efficiency.

[0034] Therefore, in this embodiment, when constructing the main pole 221 and the complementary pole 222, a new configuration is adopted in which multiple permanent magnet sheets 221a and 222a having the same orientation direction are stacked, and further, as necessary, the main pole 221 and the complementary pole 222 are divided in a direction different from the stacking direction.

[0035] Specifically, the main pole 221 is constructed by stacking permanent magnet sheets 221a of approximately the same thickness t1 in a circumferential direction (R±90°) perpendicular to the orientation direction, and the secondary pole 222 is constructed by stacking permanent magnet sheets 222a of approximately the same thickness t2 in a direction perpendicular to the orientation direction (±α±90°). In this embodiment, the permanent magnet sheets 221a and 222a are made of the same material, and their external dimensions, including the thickness dimensions t1 and t2, are approximately the same. The effects of adopting a stacked or segmented structure are similar even when the thickness dimensions t1 and t2 are different.

[0036] Figure 2 illustrates the dimensional relationship between the main pole 221 and the auxiliary pole 222. The vertical dimensions b1 and b2 of the main pole 221 and the auxiliary pole 222, as well as the axial dimensions c1 and c2 of the main pole 221 and the auxiliary pole 222, are set to be approximately the same (identical or nearly identical) to each other.

[0037] As shown in Figure 1, the main pole 221 is further constructed by dividing the permanent magnet sheet 221a into equal parts on the dividing surface 221x in the direction perpendicular to the thickness direction (radial direction). The illustrated example shows a case with two divisions, but the number of divisions is not limited to this. Although not shown, the complementary pole 222 may be divided in the same way.

[0038] In Figure 3(a), where permanent magnets (main pole 221 and auxiliary pole 222) form a cluster, the cross-section through which eddy currents flow becomes smaller in Figure 3(b), where the permanent magnets are arranged in a stacked structure. Furthermore, in Figure 3(c), where this structure is divided, the cross-section through which eddy currents flow becomes even smaller. As a result, the eddy current loss is smaller in the structure of Figure 3(b) than in the structure of Figure 3(a), and even smaller in the structure of Figure 3(c) than in the structure of Figure 3(b). This suppresses heat generation in the magnet 22 and the decrease in motor efficiency, allowing for the flow of larger currents. Therefore, it becomes possible to increase the power density of the motor through higher excitation frequencies achieved by using multiple poles.

[0039] As shown in Figure 3(d), the permanent magnet may also be divided into multiple sections in the axial direction.

[0040] In order to realize such a stacked structure of main poles 221 and complementary poles 222, this embodiment employs the magnet manufacturing method shown in Figure 4.

[0041] First, thin permanent magnet sheets 221a (222a) are cut from the permanent magnet block as shown in Figure 4(a). Next, as shown in Figure 4(b), multiple permanent magnet sheets 221a (222a) are bonded together, and then, as shown in Figure 4(c1), the main pole 221 is cut from the laminate of permanent magnet sheets 221a, and as shown in Figure 4(c2), the complementary pole 222 is cut from the laminate of permanent magnet sheets 222a.

[0042] The main pole 221 is cut out from the edge direction of the laminate using a tool or processing machine along a rectangle x1 with two sides aligned with the lamination direction. The auxiliary pole 222 is cut out from the edge direction of the laminate using a tool or processing machine along a rectangle x2 oblique to the lamination direction.

[0043] Then, as shown in Figure 4(d), the main electrode 221 and the secondary electrode 222 are bonded together. Since the main electrode 221 is divided into two parts in the orientation direction, the two parts are bonded together to form one main electrode 221. The number of divisions is merely an example.

[0044] If it is possible to produce permanent magnets with multiple orientations (main pole 221 and complementary pole 222) using a single type of finishing jig, then only one type of finishing jig can be used, which can reduce magnet manufacturing costs such as mold costs and processing costs.

[0045] Regarding the magnetization process, in the case of a conventional Halbach array magnet as shown in Figure 5(a), if the main pole I, which is radially oriented of the rotor 2, and the co-pole II, which is circumferentially oriented of the rotor 2, are integrated, the magnetic field generated by the magnetization coil and the orientation direction of the permanent magnet are not parallel, making it impossible to generate an appropriate magnetic field that passes through the main pole I and co-pole II to magnetize the permanent magnet.

[0046] In particular, as shown in Figure 5(a1), in a multi-pole structure, if a magnetic field is to be generated that passes through all of the main pole I and co-pole II, which have different orientations, it becomes difficult to manufacture a coil capable of generating the magnetic field necessary to magnetize them.

[0047] Conversely, as shown in Figure 5(a2), if magnetization is performed on the main pole I and co-pole II individually, the number of magnetization steps increases. Furthermore, when attaching the main pole I and co-pole II to the rotor core 21, the magnetic attractive and repulsive forces between the main pole I and co-pole II are large, and the attachment work becomes difficult because the poles are frequently subjected to these magnetic attractive and repulsive forces.

[0048] Therefore, as shown in Figure 5(b), the orientation direction of the co-pole 222 is set to an acute angle ±α with respect to the orientation direction of the main pole 221, and as shown in Figure 5(c), the unmagnetized main pole 221 and co-pole 22 are attached to form a single-pole permanent magnet unit 22a, and then a magnetic field is applied to each permanent magnet unit 22a to perform magnetization.

[0049] The permanent magnet unit 22a in Figure 5(c) is actually arranged around the rotor core 21, resulting in the fan shape shown in Figure 6(a).

[0050] Figure 6(a) shows the magnetized state in units of permanent magnet units 22a, that is, one main pole 221 and two complementary poles 222. Adjacent permanent magnet units 22a are magnetized such that their S poles and N poles are in opposite positions. By attaching these permanent magnet units 22a to the rotor core 21, the attached state shown in Figure 6(b) is completed.

[0051] According to this method, the effort involved in magnetizing each permanent magnet I to IX individually before attaching them to the rotor core 21, as well as the magnetic influence between permanent magnets, are eliminated. Furthermore, the problem of generating a strong magnetic flux for magnetization, as would be the case when all permanent magnets I to IX are attached to the rotor core 21 and then magnetized simultaneously, is also eliminated. This allows for magnetization with an appropriate magnetic flux, and since the attachment to the rotor core 21 is already completed in units of permanent magnet units 22a, all that remains is for the permanent magnet units 22a to be subjected to magnetic action between them, thus minimizing the effects of magnetic attraction and repulsion.

[0052] The permanent magnet unit 22a, consisting of the main pole 221 and the auxiliary pole 222, is held in the magnet holder 210 of the rotor core 21 shown in Figure 1. The magnet holder 210 has a wall-like portion 210a that projects radially from the cylindrical rotor core 21 at equal angular intervals, perpendicular to the thrust generation direction, and extends between the permanent magnet units 22a to near the gap between the stator 3 and the rotor 2, and an enlarged portion 210b that extends from the tip of the wall-like portion 210a in the circumferential direction (T-shape direction) of the rotor core 21 so as to overlap with the corner of the auxiliary pole 222 on the end side of the permanent magnet unit 22a. The enlarged portion 210b mechanically holds the corners of the auxiliary poles 222 of adjacent permanent magnet units 22a in the radial direction. The wall-like portion 210a may be configured to serve the role of holding the permanent magnet unit 22a in the circumferential direction.

[0053] In this configuration, a notch 222b is provided at the end corner of the co-pole 222, and the enlarged portion 210b is shaped to follow the notch 222b, thereby making the outer surface 22a1 of the permanent magnet unit 22a and the outer surface 210b1 of the enlarged portion 210b substantially flush. The notch 222b is a slope along the orientation direction of the co-pole 222 constituting the permanent magnet unit 22a, and the enlarged portion 210b is shaped as an inverted triangular taper along the slope.

[0054] In the case of the parallel-oriented magnet 22' shown in Figure 7(a), a short circuit is likely to occur through the magnet holder 210 if one is provided. In contrast, in the case of the flux-concentrating magnet 22 shown in Figure 7(b), by holding it with a magnet holder 210 that has an expanded portion along the orientation direction, even if a magnet holder 210 is provided, the complementary pole orientation direction is tilted toward the center of the magnetic pole, making a short circuit through the magnet holder 210 less likely and reducing magnetic flux leakage.

[0055] Furthermore, by holding the magnet 22 with the magnet holding part 210 which is integrated with the rotor core 21, the mechanical holding of the magnet 22 can be achieved using only the magnetic circuit components of the motor M, thus eliminating the need for the cylindrical magnet holding part 210' shown in Figure 7(c). Additionally, since the enlarged portion 210b is housed in the notch portion 222b, the gap length between the stator 3 and rotor 2 shown in Figure 1 can be reduced, resulting in an effect of increasing the fundamental wave component of the magnetic flux density provided by the magnet 22.

[0056] Furthermore, under a magnetic flux concentration structure such as a Halbach array, as is clear from the comparison between the original magnetic flux (parallel magnetic flux) other than the short-circuit magnetic flux H' shown in Figure 7(a) and the original magnetic flux other than the short-circuit magnetic flux H (magnetic flux consisting of the main pole 221 and the complementary pole 222) shown in Figure 7(b), the effect of increasing the fundamental wave component of the magnetic flux density due to the magnet 22 is obtained when the original magnetic flux is directed toward the center of the magnetic pole.

[0057] Furthermore, in a motor of the same size and current, if the fundamental wave component of the magnetic flux density due to magnet 22 increases due to the two effects described above, the torque will increase because the torque is proportional to the product of the fundamental wave of the current in the slot, the fundamental wave of the magnetic flux density, and the motor stacking thickness.

[0058] Furthermore, in motors of the same size and torque, if the magnetic flux density due to magnet 22 increases due to the two effects mentioned above, copper loss will decrease because copper loss is proportional to the product of the square of the slot current and the winding resistance. As copper loss decreases, motor input decreases, which leads to an increase in motor efficiency, which is the ratio of output to input.

[0059] Furthermore, in a motor with the same current and torque, the magnetic flux density from the magnet 22 increases due to the two effects described above, which reduces the motor's stacking thickness and allows for a smaller and lighter motor M.

[0060] In this way, by eliminating the cylindrical magnet holding component 210' to reduce the gap length, and by making the magnet 22 a magnetic flux concentration type such as a Halbach array to minimize short circuits of magnetic flux, the magnetic flux density from the magnet 22 is increased, making it possible to increase torque, increase efficiency, and reduce size and weight.

[0061] Therefore, if this motor M is applied to fields where miniaturization and weight reduction are important, such as high-power density motors for aircraft and automobiles, it can be made smaller and lighter, and because of the mechanical holding structure described above, it can be used as a motor that can operate even in temperature environments with large temperature differences.

[0062] As described above, the magnet 22 of this embodiment is characterized by comprising a permanent magnet unit 22a consisting of a main pole 221 formed by stacking permanent magnet sheets 221a of substantially the same thickness in the thickness direction, and a secondary pole 222 formed by stacking permanent magnet sheets 222a of substantially the same thickness in the thickness direction and arranging them adjacent to the main pole 221 with a different orientation direction from the main pole 221, thereby concentrating magnetic flux on the main pole 221.

[0063] Thus, by using a laminated structure of permanent magnet sheets 221a and 222a for the main pole 221 and co-pole 222, the orientation direction can be set with greater precision compared to when the main pole 221 and co-pole 222 are solid blocks of permanent magnets, making it possible to easily and appropriately manufacture a flux-concentrating permanent magnet unit 22a with high magnetic flux density. Moreover, since eddy currents are reduced by dividing the magnet, eddy current losses are reduced, and through the resulting temperature decrease, a high magnetic flux density as a flux-concentrating magnet like a Halbach array can be achieved, enabling further miniaturization and higher output when applied to motors and the like.

[0064] In this case, the permanent magnet sheet 221a constituting the main pole 221 and the permanent magnet sheet 222a constituting the complementary pole 222 have the same orientation direction with respect to the sheet coordinate system, making it easier to manufacture the main pole 221 and complementary pole 222.

[0065] Furthermore, since the permanent magnet sheet 221a constituting the main pole 221 and the permanent magnet sheet 222a constituting the complementary pole 222 have the same thickness dimension with respect to the sheet coordinate system, the main pole 221 and complementary pole 222 become even easier to manufacture.

[0066] Furthermore, the main pole 221 is further divided in a direction perpendicular to the thickness direction, which further reduces the surface area that generates eddy current losses. This reduces eddy current losses and increases magnetic flux density, enabling even smaller and higher-power designs when applied to motors and the like.

[0067] Furthermore, the main pole 221 and the complementary pole 222 have nearly identical external dimensions in some areas, which simplifies the process of matching dimensions and thus facilitates the manufacture of the permanent magnet unit 22a.

[0068] Furthermore, the permanent magnet unit 22a is arranged along the thrust generation direction, and a part of the rotor core 21 has a magnet holding portion 210 which consists of a wall-like portion 210a extending radially between the permanent magnet units 22a, 22a in a direction perpendicular to the thrust generation direction, and an enlarged portion 210b extending from the end of the wall-like portion 210a in a direction overlapping with the corner on the end side of the auxiliary pole 222 of the permanent magnet unit 22a.

[0069] The structure, in which the enlarged portion 210b holds the permanent magnet unit 22a, makes it possible to hold the permanent magnet using only the motor's magnetic circuit components. In this case, by providing a notch 222b at the corner of the auxiliary pole 222 of the permanent magnet unit 22a to accommodate the enlarged portion 210b, it is possible to avoid an increase in the gap length between the stator 3 and the movable portion 2 when applied to a motor or the like. Furthermore, when the corner is held in place by the enlarged portion 210b, if it is a flux-concentrating magnet such as a Halbach array, the leakage of magnetic flux through the enlarged portion 210b will be reduced compared to a parallel-oriented magnet, so the permanent magnet unit 22a can be properly held without significantly reducing the magnetic flux density.

[0070] Furthermore, since the notch 222b is a slope along the orientation direction of the co-poles 222 that constitute the permanent magnet unit 22a, and the enlarged portion 210b has a tapered shape along that slope, even if the magnet holding portion 210 is provided, the magnetic flux is less likely to flow through the magnet holding portion 210 to the rotor core 21, and the fundamental wave component of the magnetic flux density due to the magnet can be increased.

[0071] Applying such magnets to the rotor 2 of a motor M would allow for the appropriate construction of a compact, lightweight, high-torque, and highly efficient multi-pole surface magnet type rotor 2, which would greatly expand its potential use in applications such as aircraft motors.

[0072] As a method for manufacturing the magnets, the main pole 221 is constructed by cutting from a predetermined direction onto a laminate formed by stacking permanent magnet sheets 221a, and the auxiliary pole 222 is constructed by cutting from a different direction onto a laminate formed by stacking permanent magnet sheets 222a having the same orientation as the permanent magnet sheets 221a of the main pole 221, so that in the motor coordinate system assembled adjacent to the main pole 221, the orientation direction is different from that of the main pole 221.

[0073] In this way, it is possible to easily manufacture main poles 221 and complementary poles 222 with different orientations when assembled, while minimizing eddy current losses using a similar manufacturing process. From the perspective of a manufacturing method that involves cutting permanent magnet sheets 221a and 222a having the same orientation with respect to the sheet coordinate system from different directions, the thickness of the permanent magnet sheets 221a and 222a does not have to be the same, nor do the materials of the permanent magnet sheets 221a and 222a have to be the same.

[0074] If the same jig is used for cutting out the main pole 221 and the auxiliary pole 222, the main pole 221 and auxiliary pole 222 of the same dimensions can be easily manufactured.

[0075] Furthermore, the cut main electrode 221 and auxiliary electrode 222 may be subjected to post-processing such as chamfering as needed. Even if the final form differs, the manufacturing process can be simplified by performing the same processing steps up to a certain point.

[0076] Although one embodiment of the present invention has been described above, the specific configuration of each part is not limited to the embodiment described above.

[0077] The thickness dimension t1 of the permanent magnet sheet 221a constituting the main pole 221 and the thickness dimension t2 of the permanent magnet sheet 222a constituting the complementary pole 222 may be different.

[0078] Furthermore, the magnetic materials for the main pole 221 and the secondary pole 22 may be different. By selecting a material with high coercivity for the one that is easily demagnetized and a material with high residual magnetic flux density for the one that is not easily demagnetized, it is possible to create a magnet 22 with high residual magnetic flux density and resistance to demagnetization.

[0079] In the above embodiment, the main pole 221 is divided radially, and the co-pole 222 is not divided. However, as shown in Figure 8(a), the co-pole 222 may be divided perpendicular to the orientation direction. By increasing the number of dividing surfaces 222x, eddy current losses can be further reduced.

[0080] Furthermore, as shown in Figure 8(b), a second co-pole 223 may be added. In the illustrated example, the orientation direction of the second co-pole 223 is perpendicular to the orientation direction of the main pole 221, but it may also be oblique (e.g., 30°, 45°, 60°, etc.). By increasing the number of co-pole 222 and 223 so that the magnetic flux concentrates on the main pole 221, the magnetic flux density of the magnet can be made closer to the fundamental wave component, which is a sine wave. In addition, the added co-pole 223 can also have a dividing surface 223x to reduce eddy current losses.

[0081] Furthermore, as shown in Figure 9, the enlarged portion 210b of the magnet holding portion 210 by the rotor core 21 does not need to be embedded in the magnet 22. Doing so eliminates the need to chamfer the corners of the magnet, thus increasing the magnetic flux density of the magnet 22. However, if the interpole corners are not chamfered, the magnetic flux from the interpole corners toward the stator core 31 can more easily pass through the gap between the stator 2 and the rotor 1 via the enlarged portion 210b of the magnet holding portion 210. As a result, the permeability between the gap between the stator 2 and the rotor 1 increases, the inductance increases, and the power factor decreases, so this can be applied within an acceptable range.

[0082] Furthermore, as shown in Figure 10(a1), by making the magnet holding surface 210b1 of the enlarged portion 210b constituting the magnet holding portion 210 tapered in a direction parallel to the magnetization direction of the auxiliary pole 222 constituting the permanent magnet unit 22a, the magnetic flux H becomes less likely to pass through the enlarged portion 210b constituting the magnet holding portion 210, thereby increasing the fundamental wave component of the original magnetic flux density.

[0083] Figure 10(a2) shows, as a comparative example, a case in which the magnet holding surface 210b2 of the enlarged portion 210b constituting the magnet holding portion 210 has an angle with respect to the magnetization direction. In this case, the magnetic flux H can pass more easily through the enlarged portion 210b constituting the magnet holding portion 210, and the fundamental wave component of the original magnetic flux density is reduced.

[0084] Thus, the tapered shape of the magnet holder 210 shown in Figure 10(a1) is more effective in preventing short circuits of magnetic flux in terms of magnetic flux density compared to the shape of the magnet holder 210 shown in Figure 10(a2). However, the area effective for holding the magnet becomes smaller, and the force holding the magnet becomes weaker. Therefore, its application is effective only within an acceptable range.

[0085] Furthermore, as shown in Figure 10(b), the wall-like portion 210a constituting the magnet holding portion 210 may be made into an intermittent structure (comb-shaped) along the direction of the motor shaft m by providing a notch or material removal in a part of it. In this case, the volume of magnetic material between the gap between the stator 3 and the rotor 2 shown in Figure 1 is reduced, so the inductance is reduced and the power factor can be improved.

[0086] Alternatively, adhesive may be applied to the contact surface between the wall-like portion 210a constituting the magnet holding portion 210 shown in Figure 11 and the auxiliary pole 222, or to the contact surface between the outer circumference of the rotor core 21 and the main pole 221 or auxiliary pole 222, thereby creating an adhesive holding structure between the rotor core 21 and the permanent magnet unit 22a. By filling the gap between the permanent magnet unit 22a and the rotor core 21 with adhesive, it is possible to prevent the permanent magnet unit 22a and the rotor core 21 from colliding due to differences in the coefficient of thermal expansion or changes in the gap due to dimensional tolerances.

[0087] Furthermore, the presence of the wall-like portion 210a of the magnetic pole holding portion 210 between the permanent magnet units 22a, 22a (between the complementary poles 222, 222) makes it easier to hold the permanent magnet units 22a. Therefore, if magnets can be held by adhesive or other means, the magnet holding portion 210 can be constructed using only the wall-like portion 210a, as shown in Figure 11, eliminating the enlarged portion and significantly increasing the effect of suppressing short-circuit magnetic flux.

[0088] Furthermore, when applied to an outer rotor type motor, the main pole and complementary pole can be assembled by bonding them to the inner circumference of the rotor core.

[0089] Furthermore, a magnet equipped with the permanent magnet unit of the present invention, or a method for manufacturing the same, may be applied to the stator or movable part of a linear motor or other linear-acting electric machine.

[0090] When applied to a linear-acting electric machine, as shown in Figure 12, the main pole 221 of the magnet unit 22a is oriented in a direction perpendicular to the thrust generation direction, which is the extension direction of the core 21, and the secondary pole 222 of the magnet unit 22a is arranged to face a direction that makes a predetermined angle (±α: α is preferably acute) with respect to the orientation direction of the main pole 221. In this case, a magnet holder similar to the magnet holder 210 in the above embodiment may be provided between the magnet units 22a, 22a.

[0091] Other configurations can also be modified in various ways without departing from the spirit of the present invention. [Explanation of symbols]

[0092] A... Electric motor 2… Rotor 3...Stator 21…Rotor core 22…Magnets 22a... Permanent magnet unit 210...Magnet holder 210a...Wall-like part 210b... Enlarged section 221…Main pole 222... Complementary pole 221a, 222a... Permanent magnet sheets

Claims

1. A main pole is formed by laminating permanent magnet sheets having approximately the same thickness in the thickness direction; an interpole configured to concentrate magnetic flux on the main pole by stacking permanent magnet sheets of approximately the same thickness in the thickness direction and arranging the interpole adjacent to the main pole with an orientation direction different from that of the main pole; A magnet comprising a permanent magnet unit comprising:

2. The magnet according to claim 1 , wherein the permanent magnet sheet constituting the main pole and the permanent magnet sheet constituting the interpole have the same orientation direction and thickness dimension.

3. A magnet as described in claim 1, wherein the thickness direction in which the permanent magnet sheets are stacked is a direction that intersects with the magnetization direction of the permanent magnet sheets.

4. A magnet as described in claim 1, wherein the permanent magnet sheet constituting the interpole is stacked diagonally both with respect to the stacking direction of the permanent magnet sheet constituting the main pole and with respect to a direction perpendicular to the stacking direction, and the main pole and the interpole are integrally joined to form a permanent magnet unit.

5. 5. The magnet according to claim 1, wherein at least one of the main pole and the interpole is further divided in a direction perpendicular to the thickness direction.

6. An electric motor having a rotor comprising a magnet as described in any one of claims 1 to 4, wherein the permanent magnet units of the magnet are configured one pole at a time and arranged along the thrust generation direction, and a part of the core, which is the thrust generating element, has a magnet holding portion consisting of a wall-like portion extending in a direction perpendicular to the thrust generation direction between the permanent magnet units and an enlarged portion extending from the end of this wall-like portion in a direction overlapping with the corner portion on the end side of the permanent magnet unit.

7. A step of cutting out a permanent magnet sheet along the magnetization direction of a permanent magnet block; a step of stacking the permanent magnet sheets together in a direction perpendicular to the magnetization direction of the permanent magnet sheets to obtain a laminate; a first cutting step of obtaining a main pole by cutting the laminate in a direction perpendicular to the lamination direction and the magnetization direction; a second cutting step of cutting out a comma pole from the laminate in a direction perpendicular to the lamination direction and the magnetization direction, the direction being different from the first cutting step; assembling an inter-pole adjacent to the main pole such that the inter-pole has an orientation different from that of the main pole; A method for producing a magnet, comprising:

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