Rotary electric machine

Abstract

To provide a rotary electric machine having excellent NV performance while suppressing an increase in weight and size.SOLUTION: A motor 100 comprises: a cylindrical rotor core 21; and a plurality of granule dampers 25 that are composed of a plurality of holes 26 arranged within the rotor core 21 and arrayed in a circumferential direction of the rotor core 21, and a large number of granules 27 enclosed to be movable within the holes 26.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a rotating electric machine. [Background technology]

[0002] NV (noise and vibration) generated during operation of rotating electrical machines such as motors and generators can be a problem.

[0003] For example, Patent Document 1 discloses a technology for reducing the NV of a motor, in which a damping medium consisting of a solid, paste or liquid is filled into the gap between the outer surface of the motor stator core and the inner wall of the motor housing.

[0004] Moreover, Non-Patent Document 1 discloses a granular damper that uses a plurality of particles as a damping medium. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-65082 [Non-patent literature]

[0006] [Non-Patent Document 1] Kazuo Ichikawa et al., Transactions of the Japan Society of Mechanical Engineers, Vol. 87, No. 896 (2021) Summary of the Invention [Problem to be solved by the invention]

[0007] Granular dampers do not require dense seals compared to those that use liquids, and are expected to improve damping effect by dissipating heat due to friction between particles. However, it is necessary to ensure porosity in the part where the particles are enclosed.

[0008] If such a granular damper is to be installed in a motor housing or, for example, between the outer surface of the motor stator core of a rotating electric machine and the inner wall of the motor housing as in Patent Document 1, there is a concern that the weight and size of the rotating electric machine will increase due to an increase in the thickness of the motor housing.

[0009] The present disclosure has been made in consideration of the above points, and an object of the present disclosure is to provide a rotating electrical device that has excellent NV performance while suppressing increases in weight and size. [Means for solving the problem]

[0010] The present disclosure relates to a rotating electric machine including a cylindrical rotor core, a plurality of granular dampers each including a plurality of holes arranged in the rotor core and aligned in the circumferential direction of the rotor core, and a large number of granular materials movably enclosed within the holes.

[0011] In the above-described configuration, the granular damper is disposed by utilizing the radial thickness of the rotor core, which makes it possible to improve the NV performance while suppressing increases in the weight and size of the rotating electrical machine.

[0012] The rotating electric machine may also include a plurality of magnet pairs arranged inside the rotor core and aligned in the circumferential direction, each of the plurality of magnet pairs being composed of two permanent magnets arranged in a V-shape in the circumferential direction, and the plurality of air holes being respectively arranged in the valleys of the V-shape of each of the plurality of magnet pairs.

[0013] According to the above configuration, each hole is arranged in the valley of the V-shape of the corresponding magnet pair. By arranging them in this way, the radial thickness of the rotor core can be reduced. This is advantageous for reducing the weight and size of the rotating electric machine, and ultimately for improving the NV performance.

[0014] The rotating electric machine may also include a plurality of magnet pairs arranged inside the rotor core and aligned in the circumferential direction, each of the plurality of magnet pairs being composed of two permanent magnets aligned in the circumferential direction, and each of the plurality of air holes being arranged between two adjacent magnet pairs among the plurality of magnet pairs.

[0015] According to the above configuration, each hole is disposed between two magnet pairs. By disposing the holes in this manner, the radial thickness of the rotor core can be reduced. This is advantageous for reducing the weight and size of the rotating electric machine, and therefore for improving the NV performance.

[0016] The rotating electric machine may also include a plurality of magnet pairs arranged inside the rotor core and aligned in the circumferential direction, each of the plurality of magnet pairs being composed of two permanent magnets aligned in the circumferential direction, and the plurality of air holes being arranged radially inward of each of the plurality of magnet pairs.

[0017] According to the above-mentioned configuration, each of the holes is disposed radially inward of each of the magnet pairs. By disposing in this manner, it is possible to suppress interference between each of the magnet pairs and the granular material, and to minimize the influence on the formation of the magnetic path.

[0018] The granular material may be made of a magnetic material.

[0019] According to the above-mentioned configuration, the granular material constituting the granular damper has magnetic properties, which is advantageous for forming a magnetic path inside the rotor core.

[0020] Furthermore, each of the plurality of holes may be formed by a plurality of gaps extending along the circumferential direction and aligned in a radial direction of the rotor core.

[0021] One of the factors that can cause vibration in a motor is torque fluctuation of the rotor. An inertial force caused by the torque fluctuation acts on the granular material. This inertial force acts in the opposite direction to the rotation direction of the rotor. The torque fluctuation can be mitigated by making the granular material collide with the inner wall of each gap.

[0022] According to the above-mentioned configuration, since each of the gaps extends in the circumferential direction, the granular material in each gap can be moved in the rotation direction of the rotor core, and thus the torque exerted by the granular material can be transmitted more efficiently compared to a configuration in which the granular material is moved in the radial direction.

[0023] Moreover, each of the plurality of gaps may be partitioned so as to be divided in the circumferential direction.

[0024] According to the above configuration, by dividing each gap in the circumferential direction, it is possible to shorten the moving distance of the granular material in the same direction. This makes it possible to shorten the time required for the granular material to collide with the inner wall of each gap after the torque fluctuation occurs as much as possible. This makes it possible to more reliably suppress the torque fluctuation.

[0025] The plurality of holes may be arranged in a staggered pattern in the circumferential direction and thickness direction of the rotor core.

[0026] According to the above-described configuration, the influence of each hole on the formation of a magnetic path can be suppressed as much as possible, which is advantageous for the formation of a magnetic path inside the rotor core. Effect of the Invention

[0027] As described above, according to the present disclosure, it is possible to provide a rotating electric machine that has excellent NV performance while suppressing increases in weight and size. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a diagram illustrating an entire motor, which is an example of a rotating electric machine according to the present disclosure. [Diagram 2] FIG. 2 is a partially enlarged view of the rotor of the motor shown in FIG. [Diagram 3] FIG. 3 is a diagram for explaining the operating principle of the granular material damper. [Figure 4] FIG. 4 is a diagram for explaining the operating principle of the granular material damper. [Diagram 5] FIG. 5 is a diagram for explaining the relationship between the void ratio of a granular material damper and the damping effect. [Figure 6] FIG. 6 is a plan view showing the rotor shown in FIG. 1 as viewed from the outer periphery side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Note that the following description is merely an example.

[0030] Fig. 1 is a diagram showing an entire motor 100 which is an example of a rotating electric machine according to the present disclosure. Fig. 2 is a diagram showing a part of a rotor 20 of the motor 100 shown in Fig. 1 in an enlarged manner.

[0031] <Overall motor configuration> The motor 100 shown in Fig. 1 is a permanent magnet type synchronous motor driven by three-phase alternating current. The use of the motor 100 is not particularly limited, and may be, for example, a drive motor for an electric vehicle such as a hybrid vehicle (HV) or an electric vehicle (EV), or a motor for home appliances such as an air conditioner, a washing machine, or a refrigerator. Note that the motor 100 is an example of a rotating electric machine according to the present disclosure, and is not limited to this configuration. Examples of the rotating electric machine according to the present disclosure include a motor equipped with a rotor core, a generator, and the like.

[0032] As shown in FIG. 1, the motor 100 generally includes a motor case 101, a shaft 102, a rotor 20, and a stator 30.

[0033] The motor case 101 is configured as a container having a cylindrical space therein, one end surface and the other end surface of which are sealed. The rotor 20 and the stator 30 are housed in the motor case 101.

[0034] The shaft 102 is rotatably supported by the motor case 101 with one end and the other end each protruding from the motor case 101. In this specification, terms relating to directions, such as "axial direction," "circumferential direction," "radial direction," "one end side," and "other end side," are based on the shaft 102 or the rotor core 21 of the rotor 20, unless otherwise specified to specify a different direction.

[0035] <Rotor> The rotor 20 has a cylindrical rotor core 21 , a plurality of magnet pairs 23 , and a plurality of granular material dampers 25 .

[0036] (Rotor core) The rotor core 21 is a cylindrical member formed by laminating a plurality of metal plates each having a through hole in the center. The rotor 20 rotates integrally with the shaft 102 by fixing a middle portion of the shaft 102 to the rotor core 21.

[0037] (Magnet pair) A plurality of magnet pairs 23 are arranged inside the rotor core 21. The plurality of magnet pairs 23 are lined up in the circumferential direction of the rotor core 21. Each of the plurality of magnet pairs 23 is composed of two magnets (permanent magnets) 23a, 23b lined up in a V-shape in the circumferential direction.

[0038] More specifically, the multiple magnet pairs 23 are each disposed on the outer periphery of the rotor core 21. The multiple magnet pairs 23 are disposed at equal intervals around the entire circumference of the rotor core 21. Each magnet pair 23 is configured by arranging in order in the circumferential direction a first magnet 23a with its S pole oriented radially outward and a second magnet 23b with its N pole oriented radially outward.

[0039] More specifically, the first magnet 23a and the second magnet 23b are arranged in a V-shape so as to be symmetrical with respect to an axis of symmetry extending in the radial direction. For the axis of symmetry here, see the chain line L1 in Figures 1 and 2. A V-shaped valley protruding radially inward is formed between the first magnet 23a and the second magnet 23b.

[0040] 1 and 2 are merely examples of the arrangement of the magnet pair 23. Furthermore, the order in which the first magnet 23a and the second magnet 23b are arranged is not limited to that shown in the figures.

[0041] The type and material of the first and second magnets 23a, 23b are not particularly limited as long as they are permanent magnets, and can be appropriately selected according to the specifications. Specific examples of permanent magnets include ferrite magnets, neodymium magnets, samarium-cobalt magnets, and alnico magnets. From the viewpoint of improving motor performance, it is preferable to adopt a permanent magnet that has a large holding force (coercive force) and can hold its magnetic force for a long period of time. The first and second magnets 23a, 23b may be variable magnetic force magnets that are configured to be able to change the magnitude of their magnetic force.

[0042] A cylindrical stator 30 is disposed on the outer periphery of the rotor core 21 with a small gap between it and the outer periphery of the rotor core 21 (inner rotor type).

[0043] (Granular material damper) The granular damper 25 is composed of a plurality of holes 26 and a large number of granular materials 27 sealed inside the holes 26. The plurality of holes 26 are disposed inside the rotor core 21 and are aligned in the circumferential direction of the rotor core 21. The large number of granular materials 27 are sealed inside each of the holes 26 so as to be movable.

[0044] There are roughly two types of operating principles of granular material dampers (see Non-Patent Document 1). Figures 3 and 4 are diagrams for explaining the operating principles of a granular material damper.

[0045] One of the operating principles is a vibration damping effect that utilizes the reaction force generated by collisions between freely moving particles and the container wall, as shown in Figure 3. This vibration damping effect is achieved by placing a container with a gap between the source of vibration and sealing particles equivalent to the total mass mp inside the container with a gap d between the container and the particles. This effect suppresses vibration by generating an action force Fp expressed by the following formula (1) in conjunction with the vibration of the main structure.

[0046]

number

[0047] Another operating principle is the vibration damping effect brought about by converting vibration energy into thermal energy and dissipating it by the frictional force Ff generated by contact between particles, as shown in Figure 4. The frictional force Ff in a single particle is expressed by the following formula (2), where N is the contact force and μ is the friction coefficient.

[0048]

number

[0049] -Granular body- A large number of granular materials 27 are enclosed inside each of the holes 26, but voids are also left behind. The large number of granular materials 27 are each particles, and can move inside each of the holes 26.

[0050] Specifically, the remaining rate of voids in the holes 26, that is, the porosity of the granular material damper 25, is, for example, 45 volume % or more and 80 volume % or less, and preferably 50 volume % or more and 70 volume % or less.

[0051] Fig. 5 is a diagram for explaining the relationship between the porosity of the granular damper and the damping effect. As shown in Fig. 5(a), if the porosity is less than the lower limit, the movement of the granular material 27 in the holes 26 is greatly restricted, and there is a risk that a sufficient damping effect cannot be obtained. As shown in Fig. 5(c), if the porosity exceeds the upper limit, the amount of the granular material 27 is too small, and there is a risk that a sufficient damping effect cannot be obtained. As shown in Fig. 5(b), by setting the porosity within the above range, a motor 100 with excellent NV performance can be obtained.

[0052] The material of the granular material 27 is not particularly limited, and any material generally used for granular dampers can be used. In this embodiment, the granular material 27 is made of a magnetic material. In more detail, examples of the material of the granular material 27 include metals such as aluminum, iron, and steel, and metal oxides such as zirconia. Considering the viewpoint of contributing to the formation of a magnetic path inside the rotor core 21 and the viewpoint of contributing to durability against wear and the like, it is preferable that the material of the granular material 27 is, for example, zirconia.

[0053] The particle size of the granular material 27 is not particularly limited, and particles having a particle size generally used for granular dampers can be appropriately used. Specifically, the median D(50) of the particle size distribution of the granular material 27 measured by a laser diffraction type particle size distribution measuring device is, for example, 900 μm or less, preferably 10 μm or more and 500 μm or less, and more preferably 20 μm or more and 200 μm or less. This can improve the NV performance of the motor 100.

[0054] -Vacancies- The motor 100 according to this embodiment is characterized in that the plurality of holes 26 constituting the granular material damper 25 are arranged inside the rotor core 21 as described above. As shown in FIG. 2, the plurality of holes 26 can be roughly divided into a plurality of first holes 26A, a plurality of second holes 26B, and a plurality of third holes 26C. 1 and 2, the rotor core 21 includes all of the first holes 26A, the second holes 26B, and the third holes 26C, but the present disclosure is not limited to such a configuration. It is sufficient to have at least one of the first holes 26A, the second holes 26B, and the third holes 26C.

[0055] It should be noted that the multiple first holes 26A illustrated in Fig. 1 are merely shown in schematic form. The details are as shown in Fig. 2. Specifically, the multiple first holes 26A illustrated in Fig. 2 are each disposed in the valley of the V-shape of each of the multiple magnet pairs 23 described above. The first holes 26A are disposed at equal intervals around the entire circumference of the rotor core 21.

[0056] In detail, the multiple first holes 26A in this embodiment are each composed of multiple gaps 28 extending along the circumferential direction of the rotor core 21 and arranged in the radial direction of the rotor core 21, as shown in Figures 2 and 5.

[0057] In this embodiment, the multiple voids 28 are configured in a two-layer structure in which the first voids 28A located on the inside in the radial direction and the second voids 28B located on the outside in the radial direction are adjacent to each other in the radial direction, but the structure is not limited to this. A three-layer structure may be formed by providing a third void layer and a fourth void layer.

[0058] In addition, each gap 28 is configured to have a different overall length in the circumferential direction. As an example, in this embodiment, the overall length of the second gap 28B in the circumferential direction is longer than the first gap 28A in the circumferential direction. By making the lengths different between the inside and outside in the radial direction, when the inertial force caused by the torque fluctuation of the motor 100 acts on the granular material 27, the timing at which the granular material 27 collides with the inner wall of the second gap 28B can be made different from the timing at which the granular material 27 collides with the inner wall of the first gap 28A. This is advantageous for suppressing torque fluctuation over a wider frequency range.

[0059] More specifically, as shown in FIGS. 2 and 5, each of the plurality of gaps 28 is partitioned so as to be divided in the circumferential direction.

[0060] In this embodiment, each gap 28 is divided into a first divided layer 28l and a second divided layer 28r adjacent to the first divided layer 28l in the circumferential direction. Such a configuration may be applied to both the first gap 28A and the second gap 28B, or may be applied to either one of them. In addition, the number of divisions of each gap 28 is not limited to two. The number of divisions may be different between the gaps 28.

[0061] On the other hand, as also shown in FIG. 2, each of the second holes 26B is disposed between two adjacent magnet pairs 23 among the multiple magnet pairs 23.

[0062] Similarly to the plurality of first holes 26A, each of the plurality of second holes 26B may be formed by a plurality of gaps 28 extending along the circumferential direction of rotor core 21 and aligned in the radial direction of rotor core 21. Each of the plurality of gaps 28 may be partitioned so as to be divided in the circumferential direction.

[0063] As also shown in FIG. 2, the third holes 26C are disposed radially inward of the magnet pairs 23, respectively.

[0064] Similarly to the first holes 26A, each of the third holes 26C may be formed of a plurality of gaps 28 extending circumferentially of the rotor core 21 and aligned radially of the rotor core 21. The plurality of gaps 28 may be partitioned so as to be divided in the circumferential direction.

[0065] Similarly to the plurality of first holes 26A, each of the plurality of second holes 26B may be formed by a plurality of gaps 28 extending along the circumferential direction of rotor core 21 and aligned in the radial direction of rotor core 21. Each of the plurality of gaps 28 may be partitioned so as to be divided in the circumferential direction.

[0066] Furthermore, it is even more preferable that of the three types of holes 26, namely the first holes 26A, the second holes 26B and the third holes 26C, at least the first holes 26A and the second holes 26B are arranged in a staggered pattern in the circumferential and thickness directions of the rotor core 21.

[0067] Fig. 6 is a plan view showing rotor 20 shown in Fig. 1 as seen from the outer periphery side. This plan view corresponds to a view of outer periphery surface 21a of rotor core 21 as seen along chain line L1 in Fig. 1 etc. Also, cross section AA in Fig. 6 corresponds to the motor cross section in Fig. 1. In Fig. 6, the axial direction of shaft 102 inserted into rotor core 21 corresponds to the thickness direction of rotor core 21. As shown in Fig. 6, rotor core 21 has a laminated structure in the thickness direction. This laminated structure results from the staggered arrangement of magnet pairs 23 in the axial direction of shaft 102.

[0068] The first holes 26A are arranged so as to be offset from one another for each layer. As a result, the first holes 26A according to this embodiment are arranged in a staggered manner in the circumferential and thickness directions of the rotor core 21. Although not shown, in addition to the first holes 26A, the second holes 26B may also be arranged in a staggered manner in the circumferential and thickness directions.

[0069] <Stator> 1, the stator 30 has a cylindrical stator core 31 having a laminated structure formed by stacking a plurality of plate-shaped members. The stator core 31 has a cylindrical yoke portion 32 arranged on the outer periphery and a plurality of teeth portions 33 arranged on the inner periphery.

[0070] The teeth portion 33 extends radially inward from the yoke portion 32 to a position close to the outer circumferential surface of the rotor core 21. The teeth portions 33 are provided at predetermined intervals in the circumferential direction. The gaps between adjacent teeth portions 33 form a plurality of slots 34.

[0071] The stator coils are wound around the tooth portion 33. Specifically, by winding electric wires around the tooth portion 33 in a predetermined order, a plurality of stator coils 35 arranged in the slots 34 are formed. These stator coils 35 constitute a three-phase coil group composed of U-phase, V-phase, and W-phase coils.

[0072] <Regarding NV performance> As described above, in the above embodiment, the granular damper 25 is arranged by utilizing the radial thickness of the rotor core 21 (see, for example, FIG. 2). Thereby, while suppressing an increase in the weight and size of the motor 100, the NV performance can be improved.

[0073] Also, as illustrated in FIGS. 1 and 2, each first hole 26A is arranged in the V-shaped valley between the corresponding magnet pairs 23. By arranging in this way, the radial thickness of the rotor core 21 can be suppressed. This is advantageous for suppressing the weight and size of the motor 100 and thus improving the NV performance.

[0074] Also, as illustrated in FIGS. 1 and 2, each second hole 26B is arranged between two magnet pairs 23. By arranging in this way, the radial thickness of the rotor core 21 can be suppressed. This is advantageous for suppressing the weight and size of the motor 100 and thus improving the NV performance.

[0075] Also, as illustrated in FIGS. 1 and 2, each third hole 26C is arranged inside the magnet pairs 23 in the radial direction. By arranging in this way, the interference between each magnet pair 23 and the granular material 27 can be suppressed, and the influence on the magnetic circuit formation can be suppressed as much as possible.

[0076] Also, since the granular material 27 of the granular damper 25 has magnetism, it is advantageous for magnetic circuit formation inside the rotor core 21. This configuration is particularly effective for the granular material 27 enclosed in the first hole 26A and the granular material 27 enclosed in the second hole 26B.

[0077] Furthermore, a factor that may cause vibration in the motor 100 is torque fluctuation of the rotor 20. An inertial force caused by the torque fluctuation acts on the granular material 27. This inertial force acts in the opposite direction to the rotation direction of the rotor 20. The torque fluctuation can be mitigated by causing the granular material 27 to collide with the inner walls of each gap 28.

[0078] 2, each of the gaps 28 constituting the first hole 26A extends in the circumferential direction, so that the granular material 27 in each gap 28 can move in the rotation direction of the rotor core 21. This makes it possible to transmit the torque exerted by the granular material 27 more efficiently, compared to a configuration in which the granular material 27 moves in the radial direction.

[0079] According to the embodiment, by dividing each gap 28 in the circumferential direction as shown in Fig. 2 and Fig. 6, it is possible to shorten the moving distance of the granular material 27 in the circumferential direction. This makes it possible to shorten the time required from when torque fluctuation occurs until the granular material 27 collides with the inner wall of each gap 28 as much as possible. This makes it possible to more reliably suppress torque fluctuation.

[0080] 6, by arranging the first holes 26A in a staggered manner in the circumferential and thickness directions, the influence of each of the first holes 26A on the formation of a magnetic path can be suppressed as much as possible, which is advantageous for the formation of a magnetic path inside the rotor core 21.

[0081] Furthermore, by combining the first hole 26A, the second hole 26B, and the third hole 26C, even if the effect of the granular damper 25 formed by each hole 26 is weak, the effect can be strengthened by combining multiple types of holes 26. [Explanation of symbols]

[0082] 100 Motor (rotating electric machine) 21 Rotor core 23 Magnet Pair 23a First magnet (permanent magnet) 23b Second magnet (permanent magnet) 25 Granular Damper 26 Vacancies 26A 1st hole 26B 2nd hole 26C 3rd hole 27 Granules 28 void 28A 1st cavity 28B 2nd void 28l 1st split layer 28r 2nd split layer

Claims

1. A cylindrical rotor core; a plurality of granular dampers each including a plurality of holes arranged inside the rotor core and aligned in the circumferential direction of the rotor core, and a large number of granular materials movably enclosed within the holes; A rotating electric machine characterized by:

2. 2. The rotating electric machine according to claim 1, a plurality of magnet pairs arranged inside the rotor core and aligned in the circumferential direction; Each of the plurality of magnet pairs is composed of two permanent magnets arranged in a V-shape in the circumferential direction, The plurality of holes are respectively disposed in the valleys of the V-shapes of the plurality of magnet pairs. A rotating electric machine characterized by:

3. 2. The rotating electric machine according to claim 1, a plurality of magnet pairs arranged inside the rotor core and aligned in the circumferential direction; Each of the plurality of magnet pairs is constituted by two permanent magnets arranged in the circumferential direction, Each of the plurality of holes is disposed between two adjacent magnet pairs among the plurality of magnet pairs. A rotating electric machine characterized by:

4. 2. The rotating electric machine according to claim 1, a plurality of magnet pairs arranged inside the rotor core and aligned in the circumferential direction; Each of the plurality of magnet pairs is constituted by two permanent magnets arranged in the circumferential direction, The plurality of holes are disposed radially inward of each of the plurality of magnet pairs. A rotating electric machine characterized by:

5. 2. The rotating electric machine according to claim 1, The granular material is made of a magnetic material. A rotating electric machine characterized by:

6. 2. The rotating electric machine according to claim 1, Each of the plurality of holes is formed by a plurality of gaps extending along the circumferential direction and aligned in the radial direction of the rotor core. A rotating electric machine characterized by:

7. 7. The rotating electric machine according to claim 6, Each of the plurality of gaps is partitioned so as to be divided in the circumferential direction. A rotating electric machine characterized by:

8. In the rotating electric machine according to claim 2 or 3, The plurality of holes are arranged in a staggered pattern in the circumferential direction and the thickness direction of the rotor core. A rotating electric machine characterized by:

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