JP5202455B2 - Permanent magnet embedded rotor and vacuum cleaner - Google Patents

Description

  The present invention relates to a permanent magnet embedded rotor that is used in a vacuum cleaner or the like and performs high-speed rotation. The present invention also relates to a vacuum cleaner equipped with the permanent magnet embedded rotor.

  In a magnet-embedded rotor, in order to reduce leakage magnetic flux between magnetic poles, a method of narrowly designing the magnetic path of the outer periphery between the magnetic poles of the rotor has been conventionally used. At this time, in a motor (electric) that rotates at high speed, the mechanical strength of the outer peripheral thin portion of the magnet insertion hole due to centrifugal force acting on the magnet becomes a problem.

  Conventionally, it is easy to insert a permanent magnet at the time of assembling a permanent magnet type reluctance type rotating electrical machine, and to enable mechanization of manufacture. In addition, even when the adhesive that fixes the permanent magnet deteriorates, there is no risk of permanent magnet scattering and rotor breakage in the permanent magnet type reluctance type rotating electrical machine, and high output, high efficiency, high speed, In order to achieve high reliability, the permanent magnet is supported by providing a permanent magnet positioning projection in the permanent magnet embedding hole. In addition, by optimizing the shape of the thin part in the rotor core, the permanent magnet reluctance type rotation reduces the leakage of magnetic flux generated from the permanent magnet and ensures the strength of the thin part where stress is concentrated. An electric machine has been proposed (see, for example, Patent Document 1).

  Further, in order to achieve both of ensuring the mechanical strength of the rotor (rotor) and suppressing leakage magnetic flux, the motor includes a stator (stator) and a rotor, and the rotor includes a rotating shaft, a plurality of shafts, A yoke having slots formed at positions corresponding to the magnetic poles and permanent magnets inserted into the slots. The yoke has bridges at both ends of the slot. Has been proposed in which the thickness of the rotor decreases continuously or stepwise from the rotation center side to the outer periphery of the rotor (see, for example, Patent Document 2).

JP 2001-339919 A JP-A-9-224338

  However, in the permanent magnet type reluctance type rotating electrical machine described in Patent Document 1, a large stress concentration occurs in the thin portion between the air hole on the outer peripheral side of the permanent magnet and the outer periphery of the rotor core during high speed rotation. For this reason, it is necessary to design the radial width of the thin portion so as to withstand centrifugal force. In this case, there is a problem that magnetic flux leakage between the poles increases and the rotating electrical machine characteristics deteriorate.

  Further, even with the motor described in Patent Document 2, sufficient mechanical strength may not be obtained at ultra high speed rotation in which the rotation speed of the rotor exceeds 10,000 rpm (number of rotations / minute).

  The present invention has been made to solve the above-described problems, and is capable of reducing stress generated by centrifugal force during high-speed rotation, and has an excellent permanent magnet embedded rotor and vacuum cleaner. The purpose is to provide.

The permanent magnet embedded rotor according to the present invention is:
A rotor core formed by laminating electromagnetic steel sheets;
A plurality of magnet insertion holes provided along the outer periphery of the rotor core, and embedded with permanent magnets;
A shaft hole provided at a substantially central portion of the rotor core, and the permanent magnet constituting one pole is divided into a plurality of parts and embedded in the magnet insertion hole,
The magnet insertion hole is substantially U-shaped as a whole, both ends of the magnet insertion hole are bent inward, and a circumferential end where no permanent magnet is present forms an arc-shaped air region,
The air region is configured to be disposed closer to the shaft hole side than the outer peripheral side surface of the permanent magnet, and is formed to extend to the shaft hole side from the inner peripheral side surface of the permanent magnet,
The rotor core is configured so that the radial dimension of the magnetic path in the interpolar portion is smaller than a predetermined value, and the radius of the arc of the air region located in the interpolar portion is set to be equal to that in the air region other than the interpolar portion. It is characterized by being larger than the radius of the arc.

  In the embedded permanent magnet rotor according to the present invention, the rotor core is configured such that the radial dimension of the magnetic path in the interpolar portion is smaller than a predetermined value, and the arc of the air region located in the interpolar portion By making the radius of the rotor larger than the radius of the arc of the air region other than between the poles, the stress generated by centrifugal force during high-speed rotation can be reduced and the permanent magnet embedded rotor with excellent magnetic properties Can be provided.

FIG. 3 is a diagram illustrating the first embodiment and is a cross-sectional view of the brushless DC motor 100. FIG. 3 is a diagram illustrating the first embodiment, and is a longitudinal sectional view of a brushless DC motor 100. FIG. 3 shows the first embodiment, and is a cross-sectional view of a rotor 1 that is a permanent magnet embedded rotor. FIG. 5 shows the first embodiment, and is a cross-sectional view showing a rotor 1 with a specification 1 (a) in which the air region 4a is outside the permanent magnet outer peripheral surface 3a and a specification 2 (b) inside. FIG. 5 is a diagram showing the first embodiment, and is a stress analysis diagram at the time of rotation of the specification 1 (FIG. 4A) ((a) is a diagram of the entire rotor 1, and (b) is a partially enlarged diagram). FIG. 5 is a diagram showing the first embodiment, and is a stress analysis diagram at the time of rotation of specification 2 (FIG. 4B) ((a) is a diagram of the entire rotor 1, and (b) is a partially enlarged diagram). The figure which shows Embodiment 1, and is a figure which shows the result of having compared the maximum stress on the basis of the specification 1 (a) with a table | surface. In the figure which shows Embodiment 1, the specification 3 (a) and the specification which changed the radius of the circular arc 4b of the circumferential direction edge part of the air area 4a by making the length of the linear part 4c of the outer peripheral side of the magnet insertion hole 4 constant The cross-sectional view which shows the rotor 1 with 4 (b). FIG. 5 shows the first embodiment, and is a stress analysis diagram at the time of rotation of specification 3 (FIG. 8A) ((a) is a diagram of the entire rotor 1 and (b) is a partially enlarged diagram). FIG. 5 shows the first embodiment, and is a stress analysis diagram at the time of rotation of specification 4 (FIG. 8B) ((a) is a diagram of the entire rotor 1 and (b) is a partially enlarged diagram). FIG. 5 is a diagram showing the first embodiment, and a table showing the result of comparing the maximum stress based on the specification 2 (FIG. 4B). FIG. 3 is a diagram illustrating the first embodiment, and is a diagram illustrating a distribution of magnetic flux lines of the stator 2 and the rotor 1 of the brushless DC motor 100. FIG. 5 shows the first embodiment and is a cross-sectional view of a rotor 1 having four magnet insertion holes 4. In the figure which shows Embodiment 1, when the rotor 1 is comprised by two poles, the conventional rotor 1 comprised by the two permanent magnets 3 and 1 pole were divided | segmented into the three permanent magnets 3 The cross-sectional view which shows the rotor 1 comprised with the permanent magnet 3 of 6 sheets, and was comprised by the shape of this Embodiment. The stress analysis figure at the time of rotation of the conventional rotor 1 ((a) is a figure of the whole rotor 1, (b) is the figure which expanded a part). The figure which shows Embodiment 1 and the figure which shows the result of having compared the maximum stress on the basis of the conventional rotor 1 with a table | surface. FIG. 5 shows the first embodiment, and is a cross-sectional view of the rotor 1 in which a magnet fixing portion 4d for fixing the permanent magnet 3 is provided in the magnet insertion hole 4; FIG. 5 shows the first embodiment, and is a cross-sectional view of a rotor 1 in which an adhesive or resin is poured into an air region 4a of a magnet insertion hole 4 and a permanent magnet 3 is fixed. In the figure which shows Embodiment 2, the cross-sectional view of the rotor 1 which provided the air hole 16 in the space | interval part 12 ((a) is an example in which the air hole 16 is a circle and the four permanent magnets 3 are four poles, (B) is an example in which the air holes 16 are circular and the permanent magnets 3 are six and two poles, and (c) is an example in which the air holes 16 are substantially triangular and the four permanent magnets 3 are four poles). FIG. 5 shows the second embodiment, and is a cross-sectional view of the rotor 1 in which a recess 17 is provided in the outer peripheral portion of the inter-electrode portion 12. FIG. 9 is a cross-sectional view showing the rotor 1 in which a caulking 18 (a) or a rivet 19 (b) is provided in the vicinity of the outer peripheral portion of the interpolar portion 12 in the second embodiment. FIG. 6 is a diagram showing the third embodiment, and a cross-sectional view of the rotor 1 ((a) is a cross-sectional view of the rotor 1 using the air holes 16 in the two-pole rotor 1 obtained by dividing the permanent magnet 3 into two parts; ) Is a cross-sectional view of the rotor 1 using the air hole 16 with the two-pole rotor 1 obtained by dividing the permanent magnet 3 into three parts, and (c) is the crimp 18 with the two-pole rotor 1 obtained by dividing the permanent magnet 3 into two parts. FIG. 4D is a cross-sectional view of the rotor 1 used, and FIG. 4D is a cross-sectional view of the rotor 1 using the axial positioning key groove 15a in the two-pole rotor 1 obtained by dividing the permanent magnet 3 into two parts. FIG. 6 is a diagram showing the fourth embodiment, and is a transverse cross-sectional view of a rotor 1 in which a slit 21 is provided outside a permanent magnet outer peripheral surface 3a. FIG. 10 shows the fifth embodiment and is a cross-sectional view of the brushless DC motor 200. FIG. 10 is a diagram illustrating the fifth embodiment, and is a longitudinal sectional view of a brushless DC motor 200. FIG. 10 shows the fifth embodiment and is a cross-sectional view of the rotor 101. FIG. 10 shows the fifth embodiment and is a plan view of the rotor core 110. FIG. 16 shows the fifth embodiment, and shows the stress analysis result of the rotor having a small radius of the arc 104b. FIG. 29 is a diagram illustrating the fifth embodiment and is a diagram illustrating a stress analysis result of the rotor in which the radius of the arc 104b is increased with the same magnet amount (the same thickness) as in FIG. 28; FIG. 6 is a diagram showing the fifth embodiment, and is a magnetic flux diagram when the brushless DC motor 100 shown in FIG. 1 is unloaded. FIG. 10 is a diagram illustrating the fifth embodiment and is a magnetic flux diagram when the brushless DC motor 200 is not loaded. FIG. 10 shows the fifth embodiment, and shows a stress analysis result of a rotor in which an inter-electrode portion 112 is cut linearly and an inter-electrode outer peripheral portion is narrowed. FIG. 33 is a diagram illustrating the fifth embodiment and is a diagram illustrating a stress analysis result of the rotor in which the radius of the arc 104b of the inter-electrode portion 112 is larger than that in FIG. FIG. 10 shows the fifth embodiment and is a cross-sectional view of a rotor 201 of a first modification. FIG. 10 shows the fifth embodiment and is a cross-sectional view of a rotor 301 of a second modification. FIG. 10 shows the fifth embodiment, and is a cross-sectional view of a rotor 101 in which an adhesive or resin is poured into an air region 104a of a magnet insertion hole 104 and a permanent magnet 103 is fixed.

Embodiment 1 FIG.
FIGS. 1 to 18 are diagrams showing the first embodiment. FIG. 1 is a transverse sectional view of the brushless DC motor 100, FIG. 2 is a longitudinal sectional view of the brushless DC motor 100, and FIG. 3 is an embedded permanent magnet rotor. FIG. 4 is a cross-sectional view showing the rotor 1 with a specification 1 (a) in which the air region 4a is outside the outer peripheral surface 3a of the permanent magnet and a specification 2 (b) in which the air region 4a is inside, Figure 5 shows specification 1 (
4 (a)) is a stress analysis diagram during rotation ((a) is a view of the entire rotor 1, (b) is a partially enlarged view), and FIG. 6 is a specification 2 (FIG. 4 (b)). Stress analysis diagram at the time of rotation ((a) is a diagram of the entire rotor 1, (b) is a partially enlarged diagram), FIG. 7 shows the result of comparing the maximum stress based on the specification 1 (a). FIG. 8 shows specifications 3 (a) and 4 (4) in which the radius of the circular arc 4b at the circumferential end of the air region 4a is changed with the length of the linear portion 4c on the outer peripheral side of the magnet insertion hole 4 being constant. FIG. 9 is a cross-sectional view showing the rotor 1 with b), FIG. 9 is a stress analysis diagram during rotation of the specification 3 (FIG. 8A) ((a) is a diagram of the entire rotor 1, and (b) is a part of it. FIG. 10 is a stress analysis diagram at the time of rotation of the specification 4 (FIG. 8B) ((a) is a diagram of the entire rotor 1, (b) is a partially enlarged diagram), FIG. 11 is specification 2 (Figure FIG. 12 is a table showing the results of comparing the maximum stress based on (b)), FIG. 12 is a diagram showing the distribution of magnetic flux lines of the stator 2 and the rotor 1 of the brushless DC motor 100, and FIG. FIG. 14 is a cross-sectional view of a rotor 1 having a magnet insertion hole 4. FIG. 14 shows a conventional rotor 1 composed of two permanent magnets 3 and three one pole when the rotor 1 is composed of two poles. FIG. 15 is a cross-sectional view showing a rotor 1 divided into six permanent magnets 3 and composed of six permanent magnets 3 and having the shape of the present embodiment. FIG. 15 shows stress analysis during rotation of the conventional rotor 1. FIG. ((A) is a view of the entire rotor 1, (b) is a partially enlarged view), FIG. 16 is a table showing the results of comparing the maximum stress based on the conventional rotor 1, 17 is a cross-sectional view of the rotor 1 in which a magnet fixing portion 4d for fixing the permanent magnet 3 is provided in the magnet insertion hole 4, and FIG. It is a cross-sectional view of the rotor 1 with a fixed permanent magnet 3 pouring an adhesive or resin to the air region 4a.

  The configuration of the brushless DC motor 100 will be described with reference to FIGS.

  The brushless DC motor 100 includes a stator 2 and a rotor 1 that is a permanent magnet embedded rotor.

  The stator 2 includes three teeth 6 arranged at substantially equal intervals in the circumferential direction, a stator core 5 formed inside a ring-shaped core back 8, and a winding 7 applied to each tooth 6. With.

  The teeth 6 have a substantially parallel shape from the core back 8 side toward the inside. The tip 6a (inner diameter side) of the tooth 6 has an arc shape in which both sides spread in the circumferential direction. However, it does not have to be arcuate, and may be linear, for example.

  A concentrated winding type winding 7 is applied to each of the teeth 6. For the winding 7, a magnet wire in which a copper wire is coated with an insulating coating is used.

  Three concentrated winding type windings 7 form a three-phase winding (for example, a three-phase Y-connection winding).

  The stator core 5 is configured by punching out thin electromagnetic steel sheets having a thickness of about 0.1 to 0.7 mm one by one and laminating a predetermined number. In one example, a 0.27 mm electromagnetic steel sheet is used.

  The outer diameter of the stator core 5 is, for example, about 40 mm.

  The rotor 1 includes a rotor core 10, six plate-like permanent magnets 3 inserted into the six magnet insertion holes 4 of the rotor core 10, and a rotating shaft 9. Although details will be described later, the six-pole permanent magnet 3 constitutes a two-pole rotor 1.

  Similarly to the stator core 1, the rotor core 10 is formed by punching out thin electromagnetic steel sheets having a thickness of about 0.1 to 0.7 mm one by one and laminating a predetermined number. In one example, a 0.27 mm electromagnetic steel sheet is used.

  The outer diameter of the rotor core 10 is 20 mm in one example.

  For example, the gap 11 between the rotor 1 and the stator 2 has a radial width of about 0.3 to 1.0 mm, and in one example, 0.5 mm.

  FIG. 3 shows a rotor 1 which is a permanent magnet embedded rotor. The rotor core 10 is provided with a magnet insertion hole 4 for embedding the permanent magnet 3. In the present embodiment, there are magnet insertion holes 4 at six locations, and six flat permanent magnets 3 are embedded. Although details will be described later, the permanent magnet 3 is preferably a rare earth permanent magnet having a strong magnetic force. However, other ferrite magnets may be used.

  Regarding the method for laminating thin electromagnetic steel sheets having a thickness of about 0.1 to 0.7 mm, in this embodiment, an adhesive is applied to each of the electromagnetic steel sheets and then laminated and fixed by adhesion. However, it may be fixed with caulking and rivets.

  The magnet insertion hole 4 is not the same shape as the shape of the flat permanent magnet 3, and the whole is substantially U-shaped. And both ends of the magnet insertion hole 4 are bent inward. The permanent magnet 3 does not exist in the bent portion, and this is an air region 4a.

  The air region 4a existing adjacent to the circumferential end of the permanent magnet 3 has a permeability lower than that of the electromagnetic steel plate, so that the magnetic flux is difficult to pass therethrough and has a role of controlling the magnetic path through which the magnetic flux passes.

  Regarding the side part (circumferential direction) of the permanent magnet 3, normally, the air region 4 a is widened between the permanent magnets 3 of different polarities, and the magnetic path of the interpolar part 12 is narrowed, thereby reducing the short circuit of the magnetic flux, Designed to improve the magnetic properties of the brushless DC motor 100. A shaft hole 15 is provided at the center of the rotor 1 to be fitted to the rotating shaft 9 that transmits the rotational force of the rotor 1.

  In the present embodiment, the rotor 1 is a permanent magnet embedded type, and is configured such that the shape of the end of the air region 4a at the end in the circumferential direction of the magnet insertion hole 4 is an arc 4b. The arc 4b is a part of a circle that is in contact with the linear portion 4c on the outer peripheral side of the magnet insertion hole 4.

  The air region 4a is configured to be disposed closer to the shaft hole 15 than the outer peripheral surface 3a of the permanent magnet, and the air region 4a is configured to extend closer to the shaft hole 15 than the inner peripheral surface 3b of the permanent magnet. Is done.

  If the radius of the circular arc 4b at the circumferential end of the air region 4a is changed with the length of the straight line portion 4c on the outer peripheral side of the magnet insertion hole 4 constant, the magnet insertion hole increases as the radius of the circular arc 4b increases. The circumferential width of the thin wall portion 14 is narrowed. For reasons to be described later, the larger the radius of the arc 4b is, the more preferable, but it is necessary to make it within a range in which the minimum width in the circumferential direction of the thin portion 14 between the magnet insertion holes is ensured.

  The minimum circumferential width of the thin portion 14 between the magnet insertion holes is the thickness of the electromagnetic steel sheet (about 0.1 to 0.7 mm). When the rotor 1 rotates, the thin portion 14 between the magnet insertion holes is also subjected to centrifugal force acting on the outer core portion of the permanent magnet 3 and the magnet insertion hole 4 at the time of high-speed rotation. Also, when the rotor core 10 is punched into a desired shape, the circumferential width of the thin portion 14 between the magnet insertion holes is required to be equal to or greater than a predetermined value.

Next, the operation will be described.
In the rotor 1, which is a permanent magnet embedded rotor configured as described above, the stress due to the centrifugal force acting on the outer core portion of the permanent magnet 3 and the magnet insertion hole 4 during high-speed rotation causes the stress in the magnet insertion hole 4. It concentrates on the end of the air region 4a (the root portion connected to the thin portion 14 between the magnet insertion holes).

  In the present embodiment, since the air region 4a is arranged on the inner side of the permanent magnet outer peripheral surface 3a, the end of the air region 4a where stress concentrates (the root portion connected to the thin portion 14 between the magnet insertion holes). The outer peripheral wall thickness can be increased, and the strength of this portion can be increased.

  Furthermore, by constituting the end of the air region 4a with the arc 4b, the stress acting on the permanent magnet 3 and the iron core portion outside the magnet insertion hole 4 can be dispersed and the strength by centrifugal force can be improved.

  The arc 4b at the end of the air region 4a has a greater effect of dispersing stress as the diameter increases. The diameter of the arc 4b is preferably designed so as to be larger than the radial thickness of the permanent magnet 3 and within a range in which the minimum circumferential width of the thin portion 14 between the magnet insertion holes is ensured. The minimum circumferential width of the thin portion 14 between the magnet insertion holes is the thickness of the electromagnetic steel sheet (about 0.1 to 0.7 mm).

  FIG. 4 is a cross-sectional view showing the rotor 1 with a specification 1 (a) in which the air region 4a is outside the outer peripheral surface 3a of the permanent magnet and a specification 2 (b) inside. 5 is a stress analysis diagram at the time of rotation of the specification 1 (FIG. 4 (a)) ((a) is a diagram of the entire rotor 1, and (b) is a partially enlarged diagram). Further, FIG. 6 is a stress analysis diagram at the time of rotation of the specification 2 (FIG. 4B) ((a) is a diagram of the entire rotor 1, and (b) is a partially enlarged diagram). In the stress analysis during rotation, the same number of rotations and the same amount of magnet were used in all cases.

  As shown in FIG. 5 and FIG. 6, the magnitude of the stress is represented by color intensity. The darker the color is, the greater the stress is, and it is displayed in six levels from level 1 to level 6 from the smaller stress.

  As shown in FIGS. 5 and 6, the specification 1 (FIG. 4A) and the specification 2 (FIG. 4B) are both thin from the end of the magnet insertion hole 4 toward the outside. Stress concentration is seen.

  In particular, the stress concentration at the end of the air region 4a (the root portion connected to the thin portion 14 between the magnet insertion holes) is remarkable.

  FIG. 7 is a diagram comparing the maximum stresses of specification 1 (FIG. 4A) and specification 2 (FIG. 4B). Based on the specification 1 (FIG. 4A), the maximum stress is reduced by about 11% in the specification 2 (FIG. 4B). This is an effect that the air region 4a on the side portion of the permanent magnet 3 is on the inner side of the permanent magnet outer peripheral surface 3a.

  FIG. 8 shows specifications 3 (a) and 4 (b) in which the radius of the circular arc 4b at the circumferential end of the air region 4a is changed with the length of the linear portion 4c on the outer peripheral side of the magnet insertion hole 4 being constant. 1 is a cross-sectional view of a rotor 1. 9 is a stress analysis diagram during rotation of specification 3 (FIG. 8A) ((a) is a view of the entire rotor 1, (b) is a partially enlarged view), and FIG. 10 is a specification. 4 (FIG. 8B) is a stress analysis diagram during rotation ((a) is a diagram of the entire rotor 1, and (b) is a partially enlarged diagram).

  As shown in FIG. 6, in the specification 2 (FIG. 4B), level 6 stress concentration was observed at the end of the air region 4a (the root portion connected to the thin portion 14 between the magnet insertion holes). In the specification 3 (FIG. 8A) in which the radius of the arc 4b is larger than the specification 2 (FIG. 4B), as shown in FIG. 9, the end of the air region 4a (the thin portion 14 between the magnet insertion holes). The stress concentration of level 6 is reduced to a slight extent at the root portion connected to the surface.

Further, in the specification 4 (FIG. 8B) in which the radius of the arc 4b is large, the stress at the end of the air region 4a is reduced to such an extent that the recognized level 6 stress is further reduced.

  FIG. 11 is a table comparing the maximum stress of each specification based on the specification 2 (FIG. 4B). As can be seen from FIG. 11, the maximum stress in specification 3 (FIG. 8A) is reduced by about 11% compared to specification 2 (FIG. 4B).

  In addition, in specification 4 (FIG. 8B), the maximum stress is reduced by 22% compared to specification 2 (FIG. 4B).

  Thus, the radius of the circular arc 4b at the circumferential end of the air region 4a is as large as possible within a range in which the circumferential width of the thin portion 14 between the magnet insertion holes (the thickness of the electromagnetic steel sheet) is ensured. By doing so, the strength of the rotor 1 that performs high-speed rotation can be greatly improved, and the durability and safety of the product can be greatly improved.

  Moreover, in the magnetic path between different poles, the magnetic flux of the permanent magnet 3 is short-circuited, and the stator linkage magnetic flux contributing to the torque is reduced. Therefore, a configuration in which the magnetic path between the poles is narrowed is preferable.

  FIG. 12 shows the distribution of magnetic flux lines in the stator 2 and the rotor 1. As shown in FIG. 12, the rotor 1 of the present embodiment has a two-pole configuration, but the one-pole permanent magnet 3 is divided in order to reduce stress concentration. In the example of FIG. 12, the one-pole permanent magnet 3 is divided into three.

  In the present embodiment, since the air region 4a is configured to extend inward from the inner surface 3b of the permanent magnet, the thin portion 14 between the magnet insertion holes that causes a short circuit of the magnetic flux between the poles is replaced with the permanent magnet. The thin portion 14 between the magnet insertion holes can be designed to be narrow by arranging it in a portion having a high strength inside 3. Therefore, the rotor 1 excellent in magnetic characteristics can be configured.

  In order to alleviate the stress concentration due to centrifugal force, the thin portion 14 between the magnet insertion holes can be designed to be narrower as the radius of the arc 4b at the end of the air region 4a is increased. A balance can be realized.

  As can be seen from FIG. 4 and FIG. 8, the specification 3 (FIG. 8 (a)) and the specification 4 (FIG. 8 (b)) in which the radius of the arc 4b is larger than the specification 2 (FIG. 4 (b)) are centrifugal. The stress due to the force is low, and the thin portion 14 between the magnet insertion holes is narrow. Particularly, the specification 4 (FIG. 8B) is a configuration excellent in magnetic characteristics with few short circuits of magnetic flux between the poles.

  Although this Embodiment 1 is comprised with the six permanent magnets 3, as shown in FIG. 13, it is applicable also to the rotor 1 comprised with the four permanent magnets 3. As shown in FIG. The same effects as described above can be obtained regardless of the number, size, and shape of the permanent magnets 3.

  In particular, when stress due to centrifugal force becomes a problem, the centrifugal force is reduced by dividing one permanent magnet 3 and reducing the magnet size per sheet, thereby reducing the stress. However, as the number of magnets increases, the leakage of magnetic flux between the permanent magnet 3 itself and the permanent magnets 3 in one pole increases. Therefore, this embodiment in which the thin portion 14 between the magnet insertion holes can be designed to be narrow is effective. I can say that.

  FIG. 14 shows a conventional rotor 1 constituted by two permanent magnets 3 when the rotor 1 is constituted by two poles, and six permanent magnets 3 by dividing one pole into three permanent magnets 3. It is sectional drawing which shows the rotor 1 comprised by and having the shape of this Embodiment. FIG. 15 is a stress analysis diagram during rotation of the conventional rotor 1 ((a) is a diagram of the entire rotor 1 and (b) is a partially enlarged diagram). Further, FIG. 16 is a table showing the result of comparing the maximum stress with the conventional rotor 1 as a reference.

  As can be seen from FIG. 16, in the specification 4 in which the permanent magnet 3 of each pole is divided into three, the maximum stress can be reduced by 71% compared to the conventional one. When the permanent magnet 3 is simply divided, the leakage of magnetic flux between the permanent magnet 3 itself and each of the permanent magnets 3 at each pole increases, but the diameter of the arc 4b is the same as in this embodiment (for example, specification 4). If the large and thin portion 14 between the magnet insertion holes is narrow to the same thickness as the electromagnetic steel sheet, magnetic flux leakage of the permanent magnet 3 at each pole can be suppressed, and the magnetic characteristics of the rotor 1 are excellent.

  In addition, since the first embodiment is intended to improve the strength against the centrifugal force of the rotor, as described above, in the present embodiment, the adhesive is applied to each of the electromagnetic steel sheets and then laminated. It is fixed by bonding. Thereby, the rotor 1 with higher strength can be obtained.

  When the rotor 1 as described above is configured, in order to suppress the slip of the permanent magnet 3 in the circumferential direction, a magnet fixing portion 4d for fixing the circumferential end of the permanent magnet 3 as shown in FIG. The magnet insertion hole 4 is preferably provided. In FIG. 17, the number of magnet insertion holes 4 is four, but the number of magnet insertion holes 4 may be arbitrary.

  Further, even when there is no magnet fixing portion 4d, as shown in FIG. 18, the permanent magnet 3 may be fixed by pouring an adhesive or resin into the air region 4a and hardening it. Thereby, in order to suppress the displacement at the time of rotation in the magnet insertion hole 4 of the permanent magnet 3, the rotor 1 with higher intensity | strength can be comprised.

Embodiment 2. FIG.
In Embodiment 1 described above, the end of the air region 4a on the circumferential side of the permanent magnet 3 is configured to have a partial arc 4b, and the air region 4a is located on the inner side of the permanent magnet outer peripheral surface 3a. The air region 4a is configured to extend inward from the outer peripheral surface 3a of the permanent magnet so as to reduce the centrifugal force during high-speed rotation. In this case, the strength is high. However, there is a case where the leakage of magnetic flux between the poles of the permanent magnet 3 is large and sufficient magnetic properties cannot be obtained. In such a case, the second embodiment that can reduce the leakage of magnetic flux in the interpolar portion 12 while maintaining the strength of the rotor 1 against the centrifugal force will be described.

  FIGS. 19 to 21 are diagrams showing the second embodiment. FIG. 19 is a cross-sectional view of the rotor 1 in which the air holes 16 are provided in the inter-pole portion 12 ((a) shows the permanent magnet 3 in which the air holes 16 are circles). (B) is an example in which the air holes 16 are circular and the permanent magnets 3 are six and two poles, and (c) is an example in which the air holes 16 are substantially triangular and the four permanent magnets 3 are four. 20 is a cross-sectional view of the rotor 1 provided with a recess 17 in the outer peripheral portion of the interpolar portion 12, and FIG. 21 is a caulking 18 (a) or rivet 19 ( It is a cross-sectional view which shows the rotor 1 which provided b).

  FIG. 19 shows the rotor 1 in which the air holes 16 are provided in the inter-electrode portion 12. In the present embodiment, in order to reduce the leakage of magnetic flux between the different poles, in the combination with the first embodiment, when the adjacent permanent magnets 3 have different poles, air is present near the outer peripheral surface of the interpolar portion 12. The structure which provided the hole 16 is taken.

  As shown in FIGS. 8 to 11, in the first embodiment, stress due to centrifugal force during high-speed rotation is dispersed in the arc 4 b of the air region 4 a inside the permanent magnet outer peripheral surface 3 a, so The stress near the outer periphery is greatly reduced.

As shown in FIG. 19, by providing a substantially triangular air hole 16 having a circular shape or a partial arc shape in the inter-electrode portion 12, the stress is not greatly increased. Since the magnetic path can be designed to be narrow, leakage of magnetic flux in the inter-pole portion 12 can be reduced and the magnetic characteristics can be greatly improved. Instead of one air hole 16, a large number of small holes may be provided.

  An example shown in FIG. 19A is a four-pole rotor 1 using four permanent magnets 3. In this example, there are four inter-pole portions 12 and circular air holes 16 are provided respectively.

  The example shown in FIG. 19B is a two-pole rotor 1 using six permanent magnets 3. In this example, there are two inter-electrode portions 12, and circular air holes 16 are provided respectively.

  The example shown in FIG. 19C is a 4-pole rotor 1 using four permanent magnets 3. In this example, there are four inter-pole portions 12 provided with substantially triangular air holes 16, respectively.

  As shown in FIG. 20, instead of providing the air holes 16 in the inter-electrode portion 12, a recess 17 may be provided in the outer peripheral portion of the inter-electrode portion 12. Also in this case, since the magnetic path of the interpolar portion 12 is narrowed by the amount of the depression 17, leakage of magnetic flux in the interpolar portion 12 can be reduced, and the magnetic characteristics can be greatly improved.

  Further, as shown in FIG. 21, when adjacent permanent magnets 3 have different polarities, caulking 18 or rivets 19 may be provided in the vicinity of the outer peripheral portion of the interpolar portion 12.

  FIG. 21A shows a four-pole rotor 1 using four permanent magnets 3, and caulkings 18 are provided in the vicinity of the outer peripheral portion of the interpolar portion 12 at four locations.

  FIG. 21 (b) shows a four-pole rotor 1 using four permanent magnets 3, and rivets 19 are provided in the vicinity of the outer peripheral portion of the interpolar portion 12 at four locations.

  Since the caulking 18 and the rivet 19 deteriorate the magnetic characteristics of the electromagnetic steel sheet, the same effect as that of narrowing the magnetic path of the interpolar portion 12 can be obtained, and the magnetic characteristics can be greatly improved. At the same time, it has the function of laminating and fixing electromagnetic steel sheets, and is effective in improving the strength of the rotor 1.

  The air hole 16, the caulking 18, and the rivet 19 may be used in combination as appropriate, in addition to using each independently.

  The air hole 16, the caulking 18, and the rivet 19 act so as to suppress the magnetic flux leakage by narrowing the magnetic path of the inter-pole portion 12, and are collectively referred to as “magnetic flux leakage suppressing portion”.

  The air holes 16 or the depressions 17 vibrate while suppressing magnetic flux leakage of the inter-pole portion 12 and balancing the rotor by adjusting the size of the air holes 16 or securing the strength due to centrifugal force during high-speed rotation. -Noise can be suppressed.

  The air holes 16 or the recesses 17 do not need to be communicated in the axial direction, and may be provided within a range in which the weight balance of the rotor can be achieved.

  The air holes 16 and the recesses 17 do not have to have the same shape. That is, symmetry is not a problem.

Embodiment 3 FIG.
As described above, the permanent magnet 3 having one pole is divided to reduce the centrifugal force by dividing the permanent magnet 3 having one pole in order to disperse the centrifugal force.

  In the method of the second embodiment, when the adjacent permanent magnets 3 have the same polarity, the “magnetic flux leakage suppression portions” such as the air holes 16, the depressions 17, the caulking 18, and the rivets 19 are used to block the magnetic path of the effective magnetic flux. It becomes. Therefore, in the third embodiment, when the adjacent permanent magnets 3 have different polarities, a “magnetic flux leakage suppressing portion” is provided near the outer peripheral portion of the interpolar portion 12, and the adjacent permanent magnets 3 have the same polarity. Is a configuration in which a “magnetic flux leakage suppressing portion” is provided on the shaft hole 15 side with respect to the magnet insertion hole 4 inside the interpolar portion 20.

  FIG. 22 is a diagram showing the third embodiment, and a cross-sectional view of the rotor 1 ((a) is a cross-sectional view of the rotor 1 using the air holes 16 in the two-pole rotor 1 obtained by dividing the permanent magnet 3 into two parts). (B) is a cross-sectional view of the rotor 1 using the air hole 16 in the two-pole rotor 1 obtained by dividing the permanent magnet 3 into three parts, and (c) is the two-pole rotor 1 obtained by dividing the permanent magnet 3 into two parts. FIG. 4D is a cross-sectional view of the rotor 1 using the caulking 18, and FIG. 4D is a cross-sectional view of the rotor 1 using the shaft positioning keyway 15 a in the two-pole rotor 1 obtained by dividing the permanent magnet 3 into two parts.

  A rotor 1 shown in FIG. 22A is a two-pole rotor 1 in which a permanent magnet 3 is divided into two. A circular air hole 16 is provided in the vicinity of the outer periphery of the inter-electrode portion 12. In addition, air holes 16 are arranged inside the magnet insertion holes 4 in the same-polarity portions 20 (two places) between the divided permanent magnets 3 having the same polarity. Thereby, obstruction of the magnetic path of the effective magnetic flux can be avoided.

  A rotor 1 shown in FIG. 22B is a two-pole rotor 1 in which a permanent magnet 3 is divided into three. An air hole 16 is provided in the vicinity of the outer peripheral portion of the interelectrode portion 12. In addition, air holes 16 are arranged on the inner side of the magnet insertion holes 4 in the same-polarity portions 20 (four places) between the divided permanent magnets 3 having the same polarity. Thereby, obstruction of the magnetic path of the effective magnetic flux can be avoided.

  A rotor 1 shown in FIG. 22C is a two-pole rotor 1 in which a permanent magnet 3 is divided into two. A caulking 18 is provided near the outer periphery of the inter-electrode portion 12. Further, the caulking 18 is disposed on the inner side of the magnet insertion hole 4 at the same pole portion 20 (two places) between the divided permanent magnets 3 having the same pole. Thereby, obstruction of the magnetic path of the effective magnetic flux can be avoided.

  The rotor 1 shown in FIG. 22D is a two-pole rotor 1 in which the permanent magnet 3 is divided into two. A circular air hole 16 is provided in the vicinity of the outer periphery of the inter-electrode portion 12. Further, shaft positioning key grooves 15 a formed in shaft holes 15 located on the inner side of the magnet insertion holes 4 are formed in the same-polarity portions 20 (two places) between the divided permanent magnets 3 of the same polarity. Deploy. Thereby, obstruction of the magnetic path of the effective magnetic flux can be avoided.

  As described above, according to the present embodiment, the leakage of magnetic flux between different poles can be reduced, the magnetic flux between the same poles can be used effectively, and the magnetic characteristics can be greatly improved.

Embodiment 4 FIG.
A configuration for further improving the strength and magnetic characteristics as compared with the rotor 1 as in the first to third embodiments will be described.

  FIG. 23 is a diagram showing the fourth embodiment, and is a cross-sectional view of the rotor 1 in which a slit 21 is provided outside the permanent magnet outer peripheral surface 3a.

  As shown in FIG. 23, the slit 21 is provided outside the permanent magnet outer peripheral surface 3 a of the permanent magnet 3. In this example, four long hole-shaped slits 21 are formed for one permanent magnet 3. However, the shape and number of the slits 21 are not limited to this.

The slit 21 has an effect of reducing harmonic components of the magnetic flux flowing from the rotor 1 to the stator 2. Furthermore, since the amount of iron in the outer peripheral portion of the rotor 1 is reduced, there is an effect of reducing centrifugal force due to weight reduction, which is effective in reducing stress.

  Since Embodiments 1 to 4 improve the effective magnetic flux that contributes to the torque of the brushless DC motor, a greater effect can be obtained particularly in the rotor 1 using a rare earth magnet having a high magnetic flux density.

Embodiment 5 FIG.
First, an outline of the present embodiment will be described. In the permanent magnet embedded type rotor, stress due to centrifugal force acting on the permanent magnet and the iron core portion outside the magnet insertion hole at the time of rotation concentrates on the end portion (arc portion) of the air region of the magnet insertion hole.

  At this time, if the air region is arranged on the inner side of the outer peripheral surface of the permanent magnet, the thickness of the outer periphery at the end (arc portion) of the air region where stress is concentrated can be increased, and the strength of this portion can be increased. it can.

  Further, by configuring the end of the air region with an arc, the stress due to the centrifugal force acting on the permanent magnet and the iron core portion outside the magnet insertion hole can be dispersed, and the strength due to the centrifugal force can be improved.

  However, the fact that the outer peripheral wall thickness is large means that magnetic flux is likely to flow magnetically, so that the magnetic flux that is short-circuited between the magnets increases between the poles, and the magnet torque cannot be used effectively.

  In the present embodiment, for example, the distance between the poles is cut straight, and the magnetic path in the distance between the poles is narrowed, thereby reducing the short circuit of the magnetic flux between the poles and increasing the amount of effective magnetic flux linked to the stator. I am letting.

  Normally, by reducing the outer peripheral wall thickness of the inter-electrode part here, the stress concentration due to the centrifugal force acting on the core part outside the permanent magnet and the magnet insertion hole increases, and the local strength decreases. Will bring.

  In the present embodiment, the arc that forms the air region at the circumferential end of the magnet insertion hole is further configured such that the radius of the arc positioned at the inter-pole portion is larger than the radius of the arc other than the inter-pole portion. By doing so, it is possible to disperse and relieve the stress concentration at the interelectrode portion with a greater effect.

  By configuring the arc shape that forms the air region at the circumferential end of the magnet insertion hole so that the radius of the arc located at the inter-pole portion is larger than the radius of the arc other than the inter-pole portion, A feature of the present embodiment is that it is possible to narrow the magnetic paths in many inter-polar portions.

  Since the gap between the poles is cut straight, a gap between the stator and the rotor in the gap is widened and the magnetic resistance is increased, so that the q-axis inductance of the motor is reduced. The inductance of the motor can be reduced and the controllability can be improved.

  As described above, since the magnetic path in the interpolar part is configured to be narrow, the leakage magnetic flux in the interpolar part is reduced, the interlinkage magnetic flux of the stator is increased, and the magnet torque can be increased. Thereby, a highly efficient brushless DC motor with reduced armature magnetic flux and reduced copper loss can be configured.

24 to 36 are diagrams showing the fifth embodiment. FIG. 24 is a transverse sectional view of the brushless DC motor 200. FIG. 25 is a longitudinal sectional view of the brushless DC motor 200. FIG. 27 is a plan view of the rotor core 110, FIG. 28 is a diagram showing a stress analysis result of a rotor with a small radius of the arc 104b, and FIG. 29 is a graph showing the radius of the arc 104b with the same magnet amount (same thickness) as FIG. FIG. 30 is a diagram showing the stress analysis result of the enlarged rotor, FIG. 30 is a magnetic flux diagram when the brushless DC motor 100 shown in FIG. 1 is unloaded, FIG. 31 is a magnetic flux diagram when the brushless DC motor 200 is unloaded, and FIG. FIG. 33 is a diagram showing a stress analysis result of a rotor in which the inter-electrode portion 112 is cut in a straight line and the outer peripheral portion of the inter-electrode is narrowed. FIG. The figure which shows the stress analysis result of 34 is a cross-sectional view of the rotor 201 of the first modification, FIG. 35 is a cross-sectional view of the rotor 301 of the second modification, and FIG. 36 is to fix the permanent magnet 103 by pouring adhesive or resin into the air region 104a of the magnet insertion hole 104. FIG.

  The configuration of the brushless DC motor 200 will be described with reference to FIGS. Note that the brushless DC motor 200 may be simply referred to as a motor.

  The brushless DC motor 200 includes a stator 102 and a rotor 101 that is a permanent magnet embedded rotor.

  In the stator 102, six teeth 106 arranged at substantially equal intervals in the circumferential direction are formed inside the ring-shaped core back 108, and a stator core 105 in which a slot 113 is formed between the teeth 106. And distributed windings 107 applied to the slots 113. For the winding 107, a magnet wire in which a copper wire is coated with an insulating coating is used. However, the winding method of the winding 107 is not limited to distributed winding. A concentrated winding may be used.

  Although not shown, an insulating material is applied between the winding 107 and the slot 113.

  The teeth 106 extend from the core back 108 side inward substantially in parallel. The tip end portion 106a (inner diameter side) of the tooth 106 has an arc shape in which both sides spread in the circumferential direction. However, it does not have to be arcuate, and may be linear, for example.

  The distributed winding type winding 107 forms a three-phase winding (for example, a three-phase Y-connection winding).

  The stator core 105 is formed by punching thin electromagnetic steel sheets having a thickness of about 0.1 to 0.7 mm one by one into a predetermined shape and laminating a predetermined number. In one example, a 0.27 mm electromagnetic steel sheet is used.

  The outer diameter of the stator core 105 is, for example, about 40 mm.

  The rotor 101 is provided on a rotor core 110, six plate-like permanent magnets 103 inserted into the six magnet insertion holes 104 of the rotor core 110, and both axial end surfaces of the rotor core 110. And two end plates 122 for preventing the permanent magnet 103 from coming off in the axial direction, and a rotating shaft 109 provided at a substantially central portion of the rotor core 110. Although details will be described later, the six-pole permanent magnet 103 constitutes a two-pole rotor 101.

  Similarly to the stator core 105, the rotor core 110 is formed by punching out thin electromagnetic steel sheets having a thickness of about 0.1 to 0.7 mm one by one and laminating a predetermined number. In one example, a 0.27 mm electromagnetic steel sheet is used.

  In one example, the outer diameter of the rotor core 110 is 20 mm.

For example, the gap 111 between the rotor 101 and the stator 102 has a radial width of 0.3 to 1.
It is about 0 mm, and in one example, it is 0.5 mm.

  26 and 27, the rotor 101 and the rotor core 110 will be described.

  FIG. 26 shows a rotor 101 which is a permanent magnet embedded rotor. The rotor 101 has a two-pole configuration. A permanent magnet 103 constituting one pole is divided into a plurality of pieces. In the example shown here, the permanent magnet 103 constituting one pole is divided into three. By dividing the permanent magnet 103 constituting one pole, the magnet weight per sheet is reduced, and the stress generated by the centrifugal force during high-speed rotation can be reduced. Moreover, by dividing the magnet, eddy current loss flowing in the surface of the magnet is reduced, heat generation is suppressed, and the reliability of the magnet is improved.

  Since the rotor 101 has a configuration of two poles, and the permanent magnet 103 that constitutes one pole is divided into three, the rotor 101 as a whole uses six permanent magnets 103.

  The material of the permanent magnet 103 is a neodymium rare earth magnet mainly composed of Nd—Fe—B (neodymium, iron, boron), and has a thickness of about 1 to 2 mm.

  The rotor core 110 is provided with six magnet insertion holes 104 for embedding the six permanent magnets 103.

  Regarding the method for laminating thin electromagnetic steel sheets having a thickness of about 0.1 to 0.7 mm, in this embodiment, an adhesive is applied to each of the electromagnetic steel sheets and then laminated and fixed by adhesion. However, it may be fixed with caulking and rivets.

  The magnet insertion hole 104 is not the same shape as that of the flat permanent magnet 103, but is generally U-shaped. And both ends of the magnet insertion hole 104 are bent inward. The permanent magnet 103 does not exist in this bent portion, and this is an air region 104a.

  The air region 104a existing adjacent to the circumferential end of the permanent magnet 103 has a lower magnetic permeability than the electromagnetic steel plate, so that it is difficult for the magnetic flux to pass therethrough and has a role of controlling the magnetic path through which the magnetic flux passes.

  A shaft hole 115 is provided at the center of the rotor 101 so as to be fitted to the rotation shaft 109 that transmits the rotational force of the rotor 101.

  In the present embodiment, the rotor 101 is a permanent magnet embedded type, and is configured such that the shape of the end of the air region 104a at the end in the circumferential direction of the magnet insertion hole 104 is an arc 104b. The arc 104b is a part of a circle that is in contact with the linear portion 104c on the outer peripheral side of the magnet insertion hole 104.

  The air region 104a is configured to be disposed on the shaft hole 115 side with respect to the permanent magnet outer peripheral surface 103a, and the air region 104a is configured to extend on the shaft hole 115 side with respect to the permanent magnet inner peripheral surface 103b. Is done.

  If the radius of the circular arc 104b at the circumferential end of the air region 104a is changed with the length of the linear portion 104c on the outer peripheral side of the magnet insertion hole 104 constant, the magnet insertion hole is increased as the radius of the circular arc 104b increases. The circumferential width of the thin wall portion 114 is narrowed. Although it is preferable that the radius of the arc 104b is larger, it is necessary to make it within a range in which a minimum circumferential width of the thin portion 114 between the magnet insertion holes is ensured. The minimum circumferential width of the thin portion 114 between the magnet insertion holes is the thickness of the electromagnetic steel sheet (about 0.1 to 0.7 mm).

In the rotor 101 of the present embodiment, the outer periphery is not a circle, and the outer periphery of the rotor core 110 in the inter-electrode portion 112 is cut (notched) in a substantially linear shape. This portion is referred to as a notch portion 123.

  Even if the outer periphery of the inter-electrode portion 112 is not straight, the same effect can be obtained.

  For this reason, the magnetic path in the inter-pole portion 112 is narrower than the magnetic path in the pole.

That is, where
L1 = Minimum value of the radial dimension of the magnetic path in the pole L2 = Minimum value of the radial dimension of the magnetic path in the inter-pole portion 112
L1> L2
It becomes the relationship.

  The radius of the arc 104b in the inter-pole portion 112 is larger than the radius of the arc 104b in the pole.

That is, where
R1 = radius of the arc 104b at the pole R2 = radius of the arc 104b at the inter-pole portion 112
R1 <R2
It becomes the relationship.

  Since the magnetic path in the interpolar part 112 (magnetic path in the outer peripheral part of the rotor core 110) is narrower than the magnetic path in the pole, for example, the interpolar part 112 compared to the brushless DC motor 100 shown in FIG. Leakage magnetic flux (short-circuit magnetic flux) is reduced. Therefore, the magnetic flux (stator interlinkage magnetic flux) contributing to torque increases.

  Moreover, by notching the outer peripheral part of the rotor core 110 in the interpolar part 112, the space | gap 111 becomes large, an inductance (q-axis inductance) reduces, and the controllability of the brushless DC motor 200 improves.

  However, if the outer peripheral portion of the rotor core 110 in the interpolar portion 112 is notched and the magnetic path in the interpolar portion 112 (magnetic path in the outer peripheral portion of the rotor core 110) is narrowed, the permanent magnet 103 during high-speed rotation and The end of the air region 104a of the magnet insertion hole 104 in the inter-pole portion 112 (the root portion connected to the thin portion 114 between the magnet insertion holes, X in FIG. 26) due to the centrifugal force acting on the iron core portion outside the magnet insertion hole 104. The stress concentrated in the vicinity is locally increased.

  Therefore, by making the radius R1 of the arc 104b in the inter-pole portion 112 larger than the radius R2 of the arc 104b in the pole, the end of the air region 104a of the magnet insertion hole 104 in the inter-pole portion 112 (thin wall between the magnet insertion holes). The local stress concentrated on the root portion connected to the portion 114 (in the vicinity of X in FIG. 26) can be alleviated.

Next, the relationship between the following structural requirements and the local stress concentrated on the end of the air region 104a of the magnet insertion hole 104 (the root portion connected to the thin portion 114 between the magnet insertion holes) is the result of the stress analysis. It explains using.
(1) radius of arc 104b;
(2) The magnetic path in the inter-pole portion 112 is narrower than the magnetic path in the pole (that is, L1>L2);
(3) The radius R2 of the arc 104b in the inter-pole portion 112 is made larger than the radius R1 of the arc 104b in the pole.

  FIG. 28 shows the stress analysis result when the radius of the arc 104b in the air region 104a of the magnet insertion hole 104 is smaller than that of the brushless DC motor 200 of the fifth embodiment. The magnitude of the stress is expressed by the color intensity. The darker the color, the greater the stress. The portion with the smallest stress is set as level 1, the portion with the largest stress is set as level 6, and the interval between them is expressed as level 2 to level 5 in order from the smallest according to the stress.

  The air region 104a in this case is configured to be disposed closer to the shaft hole 115 than the permanent magnet outer peripheral surface 103a, but the air region 104a extends from the permanent magnet inner peripheral surface 103b to the shaft hole 115 side. Absent. The air region 104a is located outside the inner surface 103b of the permanent magnet.

  As shown in the figure, the stress is concentrated on the end portion of the air region 104a of the magnet insertion hole 104 (the root portion connected to the thin portion 114 between the magnet insertion holes). There are some level 6 spots.

  FIG. 29 shows the stress analysis result of the rotor having the same magnet amount (same thickness) as in FIG. 28 and the same rotation speed and the larger radius of the arc 104b.

  The air region 104a is configured to be disposed on the shaft hole 115 side with respect to the permanent magnet outer peripheral surface 103a, and the air region 104a is configured to extend on the shaft hole 115 side with respect to the permanent magnet inner peripheral surface 103b. Is done. In short, this is the configuration of the brushless DC motor 100 of FIG.

  As shown in the figure, compared with FIG. 28, the radius of the arc 104b of the air region 104a is increased, and the air region 104a is configured to extend to the axial hole 115 side from the inner surface 103b of the permanent magnet. The stress concentrated on the end of the air region 104a of the magnet insertion hole 104 (the root portion connected to the thin portion 114 between the magnet insertion holes) is reduced to about 3 to 4.

  However, as shown in FIG. 30, the brushless DC motor 100 of FIG. 1 has a large amount of leakage magnetic flux in the inter-pole portion 112, and it cannot be said that the effective magnetic flux contributing to the torque is sufficient.

  FIG. 30 is a magnetic flux diagram at the time of no load of the brushless DC motor 100 (FIG. 1) according to the first embodiment. The brushless DC motor 100 of FIG. It shows that there is much leakage magnetic flux (short-circuit magnetic flux) in the intermediate portion 112.

  Therefore, in order to narrow the magnetic path of the inter-pole portion 112, for example, as shown in FIG. 31, the outer periphery in the vicinity of the inter-pole portion 112 of the rotor 1 in the brushless DC motor 100 of FIG. When the portion 123 is provided, the leakage magnetic flux of the inter-electrode portion 112 is reduced, and the effective magnetic flux (stator interlinkage magnetic flux) contributing to the torque is increased.

  However, if the outer periphery in the vicinity of the inter-electrode portion 112 of the rotor 1 in the brushless DC motor 100 of FIG. 1 is cut and the notch portion 123 is provided, the outer peripheral portion of the iron core of the inter-electrode portion 112 becomes narrow, so the inter-electrode portion The stress concentrated at the end of the air region 104a of the magnet insertion hole 104 of 112 (the root portion connected to the thin portion 114 between the magnet insertion holes, near X in FIG. 26) increases.

FIG. 32 is a diagram showing a stress analysis result of the rotor in which the inter-electrode portion 112 is cut linearly and the inter-electrode outer peripheral portion is narrowed with respect to FIG. 29, and the air region of the magnet insertion hole 104 in the inter-electrode portion 112 The stress concentrated on the end portion 104a (the root portion connected to the thin portion 114 between the magnet insertion holes, near X in FIG. 26) is increased to about level 5.

  Therefore, as in the fifth embodiment, the radius R2 of the arc 104b in the inter-pole portion 112 is made larger than the radius R1 of the arc 104b in the pole, so that the air region 104a of the magnet insertion hole 104 in the inter-pole portion 112 is formed. The stress concentrated at the end (the root portion connected to the thin portion 114 between the magnet insertion holes, near X in FIG. 26) can be reduced.

  FIG. 33 is a diagram showing a stress analysis result of the rotor in which the radius of the arc 104b of the inter-pole portion 112 is larger than that of FIG. 32 (larger than the radius R1 of the arc 104b in the pole), and R2> R1. As a result, the stress concentrated on the end of the air region 104a of the magnet insertion hole 104 in the inter-electrode portion 112 (the root portion connected to the thin portion 114 between the magnet insertion holes) is reduced to levels 3 to 4. Recognize.

  As described above, with respect to the brushless DC motor 100 of the first embodiment, the magnetic path in the interpolar part 112 is narrower than the magnetic path in the pole (that is, L1> L2), and the arc in the interpolar part 112 is obtained. By making the radius R2 of 104b larger than the radius R1 of the arc 104b in the pole, the end of the air region 104a of the magnet insertion hole 104 in the pole portion 112 (the root portion connected to the thin portion 114 between the magnet insertion holes, FIG. 26, the leakage flux of the inter-electrode portion 112 can be reduced, and the effective magnetic flux (stator interlinkage magnetic flux) contributing to the torque can be increased.

  A rotor 201 according to the first modification will be described with reference to FIG. In the rotor 101 shown in FIG. 26, the outer periphery of the rotor core 110 in the vicinity of the inter-pole portion 112 is cut out to narrow the magnetic path of the inter-pole portion 112, but the arrangement of the magnet insertion holes 104 is changed. Thus, the magnetic path of the inter-pole portion 112 may be narrowed.

  In the rotor 201 of the first modification shown in FIG. 34, the outer shape of the rotor core 110 is a circle. In the inter-electrode portion 112, the end portion (air region 104 a) on the inter-electrode portion 112 side of the magnet insertion hole 104 is disposed so as to approach the outer periphery of the rotor core 110. Thereby, the magnetic path in the interpolar part 112 is narrower than the magnetic path in the pole.

That is, where
L1 = Minimum value of the radial dimension of the magnetic path in the pole L2 = Minimum value of the radial dimension of the magnetic path in the inter-pole portion 112
L1> L2
It becomes the relationship.

  If this is left, the stress concentrated on the end of the air region 104a of the magnet insertion hole 104 in the inter-electrode portion 112 (the root portion connected to the thin-wall portion 114 between the magnet insertion holes) increases, so the arc 104b of the inter-electrode portion 112 Is made larger than the radius R1 of the arc 104b at the pole.

That is,
R1 = radius of the arc 104b at the pole R2 = radius of the arc 104b at the inter-pole portion 112
R1 <R2
It becomes the relationship.

  Even in this case, similar to the rotor 101 shown in FIG. 26, the stress concentrated on the end of the air region 104a of the magnet insertion hole 104 in the inter-electrode portion 112 (the root portion connected to the thin portion 114 between the magnet insertion holes). The magnetic flux leakage at the inter-pole portion 112 can be reduced and the effective magnetic flux (stator interlinkage magnetic flux) contributing to the torque can be increased while suppressing the level to about 3-4.

  A rotor 301 according to the second modification will be described with reference to FIG. The rotor 301 of the second modification is of a two-pole type, and one pole is constituted by two divided permanent magnets 103. Therefore, four permanent magnets 103 are used.

  As shown in FIG. 35, the two divided permanent magnets 103 constituting one pole are arranged in a substantially V shape. Thereby, the magnet quantity of the permanent magnet 103 can be increased compared with the case where it divides | segments linearly.

  Further, as in the case of the three divisions in FIG. 34, the magnetic path in the interpolar portion 112 is narrowed so that the effective magnetic flux contributing to the torque can be increased by reducing the leakage magnetic flux in the interpolar portion 112. The minimum dimension (radial direction) of the magnetic path in the inter-pole portion 112 is a predetermined dimension (L2).

  The predetermined dimension (L2) is a dimension such that the effective magnetic flux (stator interlinkage magnetic flux) contributing to the torque can be increased by reducing the leakage magnetic flux at the inter-pole portion 112. Specifically, for example, when the outer diameter of the rotor core 110 is 20 mm, L2 is about 1 mm. However, the thickness (0.1 to 0.7 mm) of the electromagnetic steel sheet is preferable.

  As in the first embodiment, when the rotor 110 is configured, the magnet fixing portion 104d for fixing the circumferential end of the permanent magnet 103 is inserted into the magnet in order to suppress the slip of the permanent magnet 103 in the circumferential direction. The hole 104 is preferably provided.

  In addition, as shown in FIG. 36, the permanent magnet 103 may be fixed by pouring an adhesive or resin into the air region 104a and hardening it. Thereby, in order to suppress the displacement at the time of rotation in the magnet insertion hole 104 of the permanent magnet 103, the rotor 110 with higher intensity | strength can be comprised.

  Further, by forming the circumferential end of the permanent magnet 103 in an arc shape (rounded), the permanent magnet 103 is permanent when the rotor 101 rotates at an extremely high speed (exceeding 10,000 rpm (number of rotations / minute)). It is possible to prevent the magnet from locally contacting the end of the air region 104a of the magnet insertion hole 104 (the root portion connected to the thin portion 114 between the magnet insertion holes), and to reduce local stress concentration.

  As described above, since the magnetic path of the interpolar portion 112 is configured to be narrow, the leakage magnetic flux of the interpolar portion 112 is reduced, the interlinkage magnetic flux of the stator 102 is increased, and the magnet torque can be increased. . Thereby, the highly efficient brushless DC motor 200 which reduced the armature magnetic flux and reduced the copper loss can be comprised.

  The shape of the circular arc 104b constituting the air region 104a at the circumferential end of the magnet insertion hole 104 is set so that the radius of the circular arc 104b located at the interpolar portion 112 is larger than the radius of the circular arc 104b other than the interpolar portion 112. By configuring, even when the magnetic path of the inter-pole portion 112 is narrowed, local stress concentration can be relaxed and a decrease in strength can be suppressed.

  Furthermore, the inductance of the brushless DC motor 200 can be reduced and the controllability can be improved by cutting the inter-electrode portion 112 into a straight line and narrowing the magnetic path of the inter-electrode portion 112.

The present invention can greatly improve the durability of a motor having a maximum rotational speed of 1 × 10 ⁴ rpm or more, improve the life and safety of the product, reduce the magnetic flux leakage of the rotor, Efficiency can be improved.

  Specifically, for example, the durability of a motor that performs high-speed rotation, such as a motor for a vacuum cleaner, can be greatly improved, and the life and safety of the product can be improved, and the energy saving performance can be improved.

DESCRIPTION OF SYMBOLS 1 Rotor, 2 Stator, 3 Permanent magnet, 3a Permanent magnet outer peripheral side surface, 3b Permanent magnet inner peripheral side surface, 4 Magnet insertion hole, 4a Air area, 4b Arc, 4c Straight part, 4d Magnet fixing part, 5 Fixing Core, 6 teeth, 6a tip, 7 windings, 8 core back, 9
Rotating shaft, 10 Rotor core, 11 Air gap, 12 Pole area, 14 Thin portion between magnet insertion holes, 15 Shaft hole, 15a Shaft positioning keyway, 16 Air hole, 17 Recess, 18 Caulking, 19 Rivet, 20 Same Inter-polar part, 21 slit, 100 brushless DC motor, 101 rotor, 102 stator, 103 permanent magnet, 103a permanent magnet outer peripheral surface, 103b permanent magnet inner peripheral surface, 104 magnet insertion hole, 104a air region, 104b arc , 104c Linear part, 104d Magnet fixing part, 105 Stator core, 106 Teeth, 106a Tip part, 107 Winding, 108 Core back, 109 Rotating shaft, 110 Rotor core, 111 Air gap, 112 Pole part, 114 Magnet insertion Thin portion between holes, 115 shaft hole, 122 end plate, 123 notch, 200 brushless DC motor.

Claims (9)

Provided with a rotor core formed by laminating magnetic steel plates,
A plurality of permanent magnets forming one pole are provided for the number of magnetic poles,
The rotor core has a plurality of magnet insertion holes that extend linearly along the outer periphery of the rotor core , and whose both ends are bent toward the center of the rotor core to form an arcuate region. a is, the linearly extending portion to the plurality of each of embedding the permanent magnet rare, a plurality of magnet insertion holes permanent magnets in said arcuate region is not present, provided for each pole,
The rotor core is adjacent to the circumferential direction of the rotor core, and a permanent magnet that forms different magnetic poles is used as an interpolar part, and the outer peripheral part of the rotor core and the arcuate part in the interpolar part . Ri of less than the minimum value of the distance between the outer peripheral portion and the arc-shaped region minimum of the rotor core in other than the inter-electrode portion of the distance between the region and the inter-electrode gap portion the arcuate region the radius of the arc permanent magnet embedded rotor characterized in that it is configured to be larger than the radius of the arc of the interpolar portion and the arc-shaped region you position other than that located . The rotor core, by the outer peripheral portion of the vicinity of the electrode The inter have him notch, the minimum value of the distance between the outer peripheral portion and the arc-shaped region of the rotor core in the interpolar portion the rotor core outer periphery and said arcuate region and distance minimum permanent magnet to that請 Motomeko 1 wherein characterized in that it is configured to be smaller than the between the in other than the interpolar portions Embedded rotor. The rotor core has a circular outer peripheral portion, and the arc-shaped region located in the inter-polar portion is closer to the outer peripheral portion of the rotor core than the arc-shaped region located outside the inter-polar portion. the Rukoto been brought close, the outer peripheral portion of the rotor core minimum value of the distance is in other than the machining gap portion between the outer peripheral portion of the rotor core in the interpolar portion the arcuate region circle claim 1 permanent magnet embedded rotor according to characterized in that it is configured to be smaller than the minimum value of the distance between the arcuate region. The rotor cores are adjacent to each other in the circumferential direction of the rotor core, and the thin-walled portion between the arc-shaped regions formed in different magnet insertion holes is used as the thin-walled portion in the circumferential direction of the rotor core . The permanent magnet embedded rotor according to any one of claims 1 to 3, wherein a minimum value of the width is configured to be the same as a thickness of the electromagnetic steel sheet . 5. The permanent magnet embedded type according to claim 1, wherein a magnet fixing portion for fixing an end of each of the plurality of permanent magnets is provided in each of the plurality of magnet insertion holes. Rotor. Wherein the arcuate region, the permanent magnet embedded rotor according to any one of claims 1 to 5 adhesive or resin is characterized Rukoto filled. Wherein each of the plurality of permanent magnets, the permanent magnet embedded rotor according to any one of claims 1 to 6, characterized in that it is constituted by a rare earth magnet. The rotor core, a permanent magnet embedded rotor according to any one of claims 1 to 7, characterized in that it is formed by laminating and contact wear by adhesive the electromagnetic steel sheet.   A vacuum cleaner comprising the embedded permanent magnet rotor according to claim 1.