JP2020078189A - Rotary machine rotor - Google Patents

Abstract

To provide a rotary machine rotor that suppresses thermal demagnetization of a permanent magnet.SOLUTION: In a rotor 10 of an IPM motor 1, since a second heat conduction layer 42 having a low heat conductivity is located on the stator 20 side (that is, the second surface 30b side) of the permanent magnet 30, the second heat conduction layer 42 prevents heat from transferring from the rotor core 14 to the permanent magnet 30. Further, since a first heat conductive layer 41 having high thermal conductivity is located on the shaft 12 side (that is, the first surface 30a side) of the permanent magnet 30, the heat transferred from the rotor core 14 to the permanent magnet 30 is radiated from the shaft 12 side of the permanent magnet 30. That is, the heat from the stator 20 is hard to be transmitted to the permanent magnet 30, and the heat of the permanent magnet 30 is easily released, such that the temperature rise of the permanent magnet 30 is easily suppressed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a rotor of a rotating machine.

  Conventionally, as a rotating machine, an IPM motor, which is a kind of inner rotor type motor and has a permanent magnet embedded in the rotor, is known. For example, Patent Document 1 below discloses a technique in which a permanent magnet is housed in a magnet hole provided in a rotor and the periphery of the permanent magnet is filled with an adhesive having excellent thermal conductivity to enhance cooling performance of the permanent magnet. Has been done.

JP 2006-2144A

  The stator of the IPM motor generates heat due to the copper loss of the coil and the iron loss of the stator during driving, and its temperature becomes higher than that of the rotor. When the periphery of the permanent magnet is filled with an adhesive material having excellent thermal conductivity, the heat of the stator is transferred to the permanent magnet housed in the magnet hole of the rotor with high efficiency, and the temperature of the permanent magnet is increased by the temperature rise. The phenomenon that the magnetic force decreases (thermal demagnetization) is likely to occur.

  An object of the present invention is to provide a rotor for a rotating machine in which thermal demagnetization of a permanent magnet is suppressed.

  A rotor of a rotating machine according to an aspect of the present invention includes a rotor having a shaft and a rotor core to which a plurality of permanent magnets are attached so as to surround the shaft, and a stator having a plurality of coils arranged on the outer periphery of the rotor. A rotor of a rotating machine comprising: a first inner side surface and a second inner side surface facing each other in a direction along a radial direction of the rotor, the first inner side surface of the rotor being The first inner surface is housed between the magnet hole and the first inner surface and the second inner surface of the magnet hole, the second inner surface being located radially inside and the second inner surface being located radially outward of the rotor. A permanent magnet having a first surface facing the first surface and a second surface facing the second inner surface, and a first heat conduction layer located between the first surface of the permanent magnet and the first inner surface of the magnet hole. And a second heat conductive layer located between the second surface of the permanent magnet and the second inner surface of the magnet hole and having a thermal conductivity lower than that of the first thermal conductive layer. With.

  In the rotor of the rotating machine, the second heat conduction layer located between the second surface of the permanent magnet and the second inner surface of the magnet hole (that is, the stator side of the permanent magnet) is the first of the permanent magnets. Since the heat conductivity is lower than the heat conductivity of the first heat conductive layer located between the surface and the first inner surface of the magnet hole (that is, the shaft side of the permanent magnet), the heat generated in the stator is Even when the heat is transferred to the rotor, heat transfer from the rotor core to the permanent magnet is suppressed. Therefore, in the rotor of the rotating machine, the temperature rise of the permanent magnet can be suppressed, and the risk of thermal demagnetization of the permanent magnet due to the temperature rise can be suppressed.

  In a rotor of a rotating machine according to another aspect, the first heat conducting layer is made of a resin containing a filler, and the second heat conducting layer is made of a resin not containing a filler.

  In a rotor of a rotating machine according to another aspect, the first heat conducting layer is made of a resin containing a filler, and the second heat conducting layer is made of a resin containing a plurality of holes.

  In a rotor of a rotating machine according to another aspect, the first heat conducting layer is made of a resin containing a filler, and the second heat conducting layer is an air layer.

  In a rotor of a rotating machine according to another embodiment, the first heat conducting layer is made of resin, and the second heat conducting layer is made of resin containing a plurality of holes.

  In a rotor of a rotating machine according to another aspect, the first heat conducting layer is made of resin and the second heat conducting layer is an air layer.

  In a rotor of a rotating machine according to another aspect, the first heat conducting layer is made of resin containing a plurality of holes, and the second heat conducting layer is an air layer.

  In a rotor of a rotating machine according to another aspect, the permanent magnet has a laminated structure in which a plurality of magnet pieces are laminated, and further includes a third heat conduction layer interposed between adjacent magnet pieces.

  In the rotor of the rotating machine according to another aspect, the area of the second region where the second inner side surface of the magnet hole and the second surface of the permanent magnet are in contact with each other through the second heat conduction layer is the hole for magnet. Is smaller than the area of the first region in which the first inner surface of the and the first surface of the permanent magnet are in contact with each other via the first heat conduction layer.

  According to the present invention, there is provided a rotor for a rotating machine in which thermal demagnetization of a permanent magnet is suppressed.

It is a schematic sectional drawing which showed the IPM motor which concerns on one Embodiment of this invention. It is a principal part enlarged view of the rotor shown in FIG. FIG. 3 is a diagram showing one mode of magnet arrangement in the rotor shown in FIG. 2. It is a figure showing magnet arrangement of a different mode. It is a figure showing magnet arrangement of a different mode. It is a figure showing magnet arrangement of a different mode. It is a figure showing magnet arrangement of a different mode. It is a figure showing magnet arrangement of a different mode. It is a figure showing magnet arrangement of a different mode. It is a figure showing magnet arrangement of a different mode. It is a figure showing magnet arrangement of a different mode.

  Various embodiments and examples will be described below with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference symbols, without redundant description.

  FIG. 1 shows an IPM motor 1 which is a rotating machine according to the embodiment. FIG. 1 shows a cross section orthogonal to the rotation axis P of the IPM motor 1. The IPM motor 1 is an inner rotor type motor that has a rotor 10 and a stator 20, and the rotor 10 is located inside the stator 20. The IPM motor 1 has a structure of 4 poles and 24 slots in this embodiment.

  The rotor 10 includes a shaft 12 and a rotor core 14.

  The shaft 12 has a cylindrical shape and extends in a direction perpendicular to the paper surface of FIG. The shaft 12 is made of, for example, stainless steel or the like. The shaft 12 has a heat radiation portion (for example, an end portion) exposed from the rotor core 14, and has a configuration capable of constantly emitting heat from the heat radiation portion.

  The rotor core 14 has a cylindrical shape and has a shaft hole 14a inside. The shaft 12 is fitted in the shaft hole 14a of the rotor core 14, and the rotor core 14 and the shaft 12 rotate integrally around the rotation axis P. The rotor core 14 is made of, for example, laminated steel plates.

  The rotor core 14 has a plurality (four in the present embodiment) of magnet holes 16. The magnet holes 16 are arranged at equal angular intervals (90 ° intervals in this embodiment) with respect to the rotation axis P. Each magnet hole 16 has a magnet accommodating portion 17 that is orthogonal to the direction of a straight line L passing through the rotation axis P of the rotor 10 (that is, the radial direction of the rotor 10) in the cross sections shown in FIGS. 1 and 2. It has a line-symmetrical shape with respect to the straight line L. 1 and 2, the magnet accommodating portion 17 has a substantially uniform width, and the inner side surfaces 16a and 16b of the magnet hole 16 in the magnet accommodating portion 17 extend in the extending direction of the straight line L. Face to face. Hereinafter, for convenience of description, among the inner side surfaces 16a and 16b of the magnet hole 16 in the magnet housing portion 17, the inner side surface on the radially inner side of the rotor 10 (that is, the shaft 12 side) is referred to as a first inner side surface 16a, and the rotor 10 The inner side surface on the outer side in the radial direction (that is, on the stator 20 side) is referred to as a second inner side surface 16b.

  A permanent magnet 30 is housed in the magnet housing portion 17 of each magnet hole 16. In the present embodiment, the permanent magnet 30 is a rare earth magnet such as a neodymium magnet. Further, in the present embodiment, the permanent magnet 30 has a rectangular parallelepiped shape. The permanent magnet 30 has a first surface 30a facing the first inner side surface 16a of the magnet hole 16 and a second surface 30b facing the second inner side surface 16b. Both the first surface 30a and the second surface 30b are smooth surfaces and are not in direct contact with the rotor core 14. The permanent magnet 30 may be one magnet body, or may be a magnet body in which a plurality of magnet pieces 32 as shown by the broken line in FIG. 2 are stacked along the extending direction of the magnet housing portion 17. Good. The size of the permanent magnet 30 can be designed to be slightly smaller than the size of the magnet housing 17. When the dimension of the permanent magnet 30 is significantly smaller than the dimension of the magnet accommodating portion 17, the magnet occupation rate in the magnet accommodating portion 17 decreases, and the dimension of the permanent magnet 30 is the same as the dimension of the magnet accommodating portion 17. In this case, workability when the permanent magnet 30 is housed in the magnet hole 16 is reduced.

  The stator 20 is a cylindrical member provided so as to surround the outer circumference of the rotor 10. A plurality of (24 in the present embodiment) coils 22 are arranged on the inner peripheral side of the stator 20. The plurality of coils 22 are arranged at equal angular intervals (15 ° intervals in this embodiment) with respect to the rotation axis P. When an AC voltage is applied to the plurality of coils 22 from an inverter circuit (not shown) or the like, a rotating magnetic field is generated on the inner peripheral side of the stator 20.

  Next, the arrangement of the permanent magnets 30 in the magnet holes 16 of the rotor core 14 will be described with reference to FIG.

  As shown in FIG. 3, the first heat conduction layer 41 is located between the first surface 30 a of the permanent magnet 30 and the first inner side surface 16 a of the magnet hole 16. The first heat conduction layer 41 is made of, for example, a filler-containing resin. The filler-containing resin has a structure in which a filler such as alumina or aluminum nitride is dispersed in a resin such as an epoxy resin. The filler may be oriented in the facing direction of the first surface 30a of the permanent magnet 30 and the first inner surface 16a of the magnet hole 16. In the first heat conduction layer 41, for example, the permanent magnet 30 in which the filler-containing resin is applied to the first surface 30a is put in the magnet hole 16, and the first surface 30a of the permanent magnet 30 and the first hole of the magnet hole 16 are formed. It is formed by filling a space between the inner side surface 16a and a filler-containing resin and curing the resin if necessary.

  Further, the second heat conduction layer 42 is located between the second surface 30b of the permanent magnet 30 and the second inner side surface 16b of the magnet hole 16. The second heat conduction layer 42 is made of, for example, a resin such as an epoxy resin and does not contain the filler. The second heat conducting layer 42 is obtained, for example, by putting the permanent magnet 30 whose resin is applied to the second surface 30b into the magnet hole 16 and then by inserting the permanent magnet 30 into the second surface 30b of the permanent magnet 30 and the second inner surface of the magnet hole 16. It is formed by filling the space between 16b and 16b with a resin and curing the resin if necessary.

  Since the first heat conduction layer 41 contains a filler having a high heat conductivity, even if the resin components of the first heat conduction layer 41 and the second heat conduction layer 42 are the same, the first heat conduction layer 41 is The conductive layer 41 as a whole has a thermal conductivity higher than that of the second thermal conductive layer 42. That is, the first heat conduction layer 41 having a relatively high heat conductivity is located on the first surface 30a side of the permanent magnet 30, and the heat conductivity is relatively high on the second surface 30b side of the permanent magnet 30. A second, lower heat conducting layer 42 is located.

  Next, heat generation and heat transfer when the IPM motor 1 is driven will be described.

  When driving the IPM motor 1, an AC voltage is applied to the coil 22 of the stator 20 to generate a rotating magnetic field on the inner peripheral side of the stator 20. Then, each permanent magnet 30 embedded in the rotor 10 is pulled by the rotating magnetic field, and the magnetic attraction force causes the rotor 10 to rotate about the rotation axis P. At this time, by applying an AC voltage to the coil 22, heat is generated in the coil 22 due to winding resistance, and the temperature of the stator 20 rises.

  On the other hand, since the rotor 10 has no coil 22 and the shaft 12 can dissipate heat, the temperature of the rotor 10 is lower than the temperature of the stator 20. Therefore, at least part of the heat of the stator 20 is transferred to the rotor 10. The heat of the stator 20 goes from the outer peripheral side of the rotor core 14 to the inner peripheral side thereof, and further to the shaft 12.

  At this time, since the second heat conduction layer 42 having a low heat conductivity is located on the stator 20 side (that is, the second surface 30b side) of the permanent magnet 30, the second heat conduction layer 42 causes the rotor core 14 to move. From the heat transfer to the permanent magnet 30 is suppressed.

  On the other hand, since the first heat conductive layer 41 having high heat conductivity is located on the shaft 12 side (that is, the first surface 30a side) of the permanent magnet 30, the heat transferred from the rotor core 14 to the permanent magnet 30 is generated. The heat is dissipated from the shaft 12 side of the permanent magnet 30.

  That is, in the above-described rotor 10, the heat from the stator 20 is hard to be transmitted to the permanent magnet 30, and the heat of the permanent magnet 30 is easily released, so that the temperature rise of the permanent magnet 30 is suppressed.

  If the thermal conductivity of the first thermal conductive layer 41 and the thermal conductivity of the second thermal conductive layer 42 are substantially the same (for example, the first thermal conductive layer 41 and the second thermal conductive layer 42). When all of 42 are made of a filler-containing resin), the heat from the stator 20 side is transferred to the permanent magnet 30 through the second heat conduction layer 42 with high efficiency, so that the temperature rise of the permanent magnet 30 is sufficient. It is difficult to suppress it.

  In the rotor 10 described above, the heat transfer of the permanent magnet 30 is suppressed by the first heat conductive layer 41 and the second heat conductive layer 42, so that the thermal demagnetization of the permanent magnet 30 due to the temperature rise is suppressed. There is. In particular, when the permanent magnet 30 is a neodymium magnet, thermal demagnetization is likely to occur. Therefore, it is effective to suppress the temperature rise of the permanent magnet 30 by the first heat conduction layer 41 and the second heat conduction layer 42.

  In addition, regarding the first heat conduction layer 41 and the second heat conduction layer 42, the thermal conductivity of the second heat conduction layer 42 is lower than that of the first heat conduction layer 41. However, it is not limited to the above-mentioned aspect.

  For example, the combination of the constituent material of the first heat conduction layer 41 and the constituent material of the second heat conduction layer 42 is not limited to the combination of the resin and the filler-containing resin, and various combinations are possible. The foamed resin containing a plurality of fine pores has a lower thermal conductivity than a non-foaming resin containing no pores, and is therefore useful as a constituent material of the second heat conductive layer 42. That is, the first heat conductive layer 41 is made of a non-foaming resin or a filler-containing resin that does not contain pores, and the second heat conductive layer 42 is made of a foamed resin, whereby the second heat conductive layer is formed. The thermal conductivity of 42 is lower than that of the first thermal conductive layer 41.

  Further, the first surface 30a and the second surface 30b of the permanent magnet 30 may not have smooth surfaces but may have a predetermined surface roughness as shown in FIG. In this case, the surface roughness of the first surface 30a and the surface roughness of the second surface 30b may be the same or different. Further, at least one of the first surface 30a and the second surface 30b may partially directly contact the rotor core 14. Since heat transfer is high in a portion where the permanent magnet 30 and the rotor core 14 directly contact each other, for example, by arranging the permanent magnet 30 so that the first surface 30a is in direct contact with the rotor core 14, the permanent magnet 30 is connected to the shaft 12 side. The heat dissipation can be improved. When both the first surface 30a and the second surface 30b are partially in direct contact with the rotor core 14, the total area in which the first surface 30a is in direct contact with the rotor core 14 is the total area in which the second surface 30b is in direct contact with the rotor core 14. By making it larger than the area, the heat radiation to the shaft 12 side becomes more dominant than the heat absorption from the stator 20 side, so that the temperature rise of the permanent magnet 30 can be effectively suppressed.

  When the permanent magnet 30 has a laminated structure in which a plurality of magnet pieces 32 are laminated, as shown in FIG. 5, the third heat conduction layer 43 is interposed between the magnet pieces 32 adjacent to each other in the laminating direction. May be. The third heat conduction layer 43 can be made of, for example, a resin such as an epoxy resin, or can be made of a filler-containing resin in order to obtain high heat conductivity. The thermal conductivity of the third thermal conductive layer 43 may be the same as the thermal conductivity of the second thermal conductive layer 42, or may be higher than the thermal conductivity of the second thermal conductive layer 42. When the thermal conductivity of the third thermal conduction layer 43 is as high as the thermal conductivity of the first thermal conduction layer 41, the heat of the permanent magnet 30 is transferred to the shaft 12 via the third thermal conduction layer 43. Can be discharged from the side. Further, as shown in FIG. 6, the permanent magnet 30 has a substantially trapezoidal cross section, and the second inner side surface 16 b of the magnet hole 16 and the second surface 30 b of the permanent magnet 30 form the second heat conduction layer 42. The area of the second area A2 that contacts with the first inner surface 16a of the magnet hole 16 and the first surface 30a of the permanent magnet 30 that contacts with the first area A1 via the first heat conduction layer 41. May be smaller than the area of. In this case, since the heat radiation to the shaft 12 side becomes more dominant than the heat absorption from the stator 20 side, the temperature rise of the permanent magnet 30 can be suppressed more effectively. A gap may be formed between the second inner surface 16b of the magnet hole 16 and the permanent magnet 30.

  As shown in FIG. 7, the permanent magnet 30 may be a magnet body in which a plurality of magnet pieces 32 are laminated along the radial direction of the rotor 10. At this time, the third heat conduction layer 43 may be interposed between the magnet pieces 32 adjacent to each other in the stacking direction. Further, in the magnet pieces 32 adjacent to each other in the stacking direction, the width dimension of the lower magnet piece 32 may be narrower than the width dimension of the upper magnet piece 32. In this case, the permanent magnet 30 has a substantially trapezoidal cross section, and the second inner side surface 16b of the magnet hole 16 and the second surface 30b of the permanent magnet 30 are in contact with each other via the second heat conduction layer 42. The area of the area A2 is smaller than the area of the first area A1 where the first inner side surface 16a of the magnet hole 16 and the first surface 30a of the permanent magnet 30 are in contact with each other through the first heat conduction layer 41. Thereby, the heat radiation to the shaft 12 side becomes more dominant than the heat absorption from the stator 20 side, and the temperature rise of the permanent magnet 30 can be suppressed more effectively. A gap may be formed between the second inner surface 16b of the magnet hole 16 and the permanent magnet 30.

  As shown in FIG. 8, even in the aspect in which the second inner side surface 16b of the magnet hole 16 partially projects, the second inner side surface 16b of the magnet hole 16 and the second surface 30b of the permanent magnet 30 have the second surface. The area of the second region A2 in contact with the heat conduction layer 42 is such that the first inner side surface 16a of the magnet hole 16 and the first surface 30a of the permanent magnet 30 are in contact with each other via the first heat conduction layer 41. The area is smaller than the area of the area A1. Thereby, the heat radiation to the shaft 12 side becomes more dominant than the heat absorption from the stator 20 side, and the temperature rise of the permanent magnet 30 can be suppressed more effectively.

  Further, the second heat conduction layer 42 may be an air layer 42A as shown in FIG. In this case, there is no inclusion between the second surface 30b of the permanent magnet 30 and the second inner side surface 16b of the magnet hole 16. The heat conductivity of the air layer 42A is extremely low, and heat transfer from the stator 20 side can be effectively suppressed due to the high heat insulating property of the air layer 42A. When the second heat conduction layer 42 is the air layer 42A, even if the first heat conduction layer 41 is made of resin, filler-containing resin, or foamed resin, the heat of the second heat conduction layer 42 is reduced. The conductivity is lower than that of the first heat conduction layer 41.

  In order to improve the positional stability of the permanent magnet 30 in the magnet hole 16, as shown in FIG. 10, the permanent magnet 30 is placed so that a part of the second surface 30b of the permanent magnet 30 is in direct contact with the rotor core 14. You may arrange. In the embodiment shown in FIG. 10, the permanent magnet 30 has a shape (bow) in which the second surface 30b is convex toward the second inner surface 16b. In the embodiment shown in FIG. 11, the permanent magnet 30 has a U-shape in which the second surface 30b is convex toward the second inner side surface 16b and the first surface 30a is also convex toward the second inner side surface 16b. It has a cross section (horseshoe cross section). In this case, the area of the region where the first inner side surface 16a of the magnet hole 16 and the first surface 30a of the permanent magnet 30 are in contact with each other via the first heat conduction layer 41 is increased, and the heat radiation to the shaft 12 side Becomes more dominant.

  The rotor according to the present invention is not limited to the above-described embodiment, but can be variously modified.

  For example, the rotating machine is a motor such as an IPM motor, and the number of poles and the number of slots of the motor can be appropriately increased or decreased.

  The permanent magnet may extend in a direction intersecting the radial direction of the rotor in a cross section orthogonal to the shaft, and does not necessarily extend in the direction orthogonal to the radial direction of the rotor. Further, the cross-sectional shape of the permanent magnet in the cross section orthogonal to the shaft is not limited to the linear shape, and may be a convex shape or a concave shape.

DESCRIPTION OF SYMBOLS 1 ... IPM motor, 10 ... Rotor, 12 ... Shaft, 14 ... Rotor core, 16 ... Magnet hole, 16a ... 1st inner side surface, 16b ... 2nd inner side surface, 20 ... Stator, 22 ... Coil, 30 ... Permanent magnet, 30a ... 1st surface, 30b ... 2nd surface, 41 ... 1st heat conduction layer, 42 ... 2nd heat conduction layer, 42A ... Air layer, 43 ... 3rd heat conduction layer.

Claims (9)

A rotor for a rotating machine, comprising: a rotor having a shaft and a rotor core to which a plurality of permanent magnets are attached so as to surround the shaft; and a stator having a plurality of coils arranged on an outer circumference of the rotor,
In a cross section orthogonal to the shaft of the rotor,
The rotor has a first inner side surface and a second inner side surface that face each other in a direction along the radial direction of the rotor, the first inner side surface is located inside the rotor in the radial direction, and the second inner side surface is the rotor inner surface. A hole for a magnet, which is located radially outward,
A permanent magnet housed between the first inner side surface and the second inner side surface of the magnet hole, and having a first surface facing the first inner side surface and a second surface facing the second inner side surface. When,
A first heat conducting layer located between the first surface of the permanent magnet and the first inner side surface of the magnet hole;
A second one located between the second surface of the permanent magnet and the second inner side surface of the magnet hole and having a thermal conductivity lower than that of the first thermal conductive layer. A rotor of a rotating machine, comprising: a heat conductive layer.   The rotor for a rotating machine according to claim 1, wherein the first heat conduction layer is made of a resin containing a filler, and the second heat conduction layer is made of a resin not containing a filler.   The rotor for a rotating machine according to claim 1, wherein the first heat conducting layer is made of a resin containing a filler, and the second heat conducting layer is made of a resin containing a plurality of holes.   The rotor for a rotating machine according to claim 1, wherein the first heat conductive layer is made of a resin containing a filler, and the second heat conductive layer is an air layer.   The rotor for a rotating machine according to claim 1, wherein the first heat conducting layer is made of resin, and the second heat conducting layer is made of resin containing a plurality of holes.   The rotor for a rotating machine according to claim 1, wherein the first heat conductive layer is made of resin, and the second heat conductive layer is an air layer.   The rotor for a rotating machine according to claim 1, wherein the first heat conducting layer is made of a resin containing a plurality of holes, and the second heat conducting layer is an air layer. The permanent magnet has a laminated structure in which a plurality of magnet pieces are laminated,
The rotor for a rotating machine according to claim 1, further comprising a third heat conduction layer interposed between the adjacent magnet pieces. The area of the second region where the second inner surface of the magnet hole and the second surface of the permanent magnet are in contact with each other through the second heat conduction layer is the area of the first inner surface of the magnet hole. The rotor for a rotating machine according to claim 1, wherein the first surface of the permanent magnet and the first surface of the permanent magnet are narrower than an area of a first region in contact with the first heat conductive layer.

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