Rotor, rotary electric machine, and refrigeration device

Abstract

Provided are technical features that enable improvement of cooling performance of a rotor. A rotor 310 according to one embodiment comprises a rotor core 311. An outer circumferential surface 311A of the rotor core 311 includes: a reference surface 311B corresponding to a part of the circumferential surface of a cylinder about a rotation axis center AX; and a groove 311C adjacent to the reference surface 311B. In a cross section perpendicular to the rotation axis center AX, when a circle virtually drawn so as to include the reference surface 311B is defined as a circle CC1, a position closest to the rotation axis center AX in a radial direction in the groove 311C is defined as a point P1, and a position that is positioned outside the point P1 in the radial direction, inside the circle CC1 in the radial direction, and furthest from the point P1 in the rotation direction of the rotor 310 in the groove 311C is defined as a point P2, the groove 311C includes a surface SF1 between the point P1 and the point P2, a surface SF2 between the point P2 and the reference surface 311B, and a surface SF3 between the point P1 and the reference surface 311B in a direction opposite to the rotation direction of the rotor 310 viewed from the point P1.

Description

Rotor, Rotating Electric Machine, Refrigeration Device

[0001] The present disclosure relates to a rotor and the like.

[0002] Conventionally, rotating electric machines are known (see, for example, Patent Document 1).

[0003] International Publication No. 2021 / 065687

[0004] By the way, there is room for improvement in the cooling performance of the rotor of a rotating electric machine.

[0005] An object of the present disclosure is to provide a technology capable of improving the cooling performance of a rotor.

[0006] In a first aspect of the present disclosure, a rotor is rotatable about a rotation axis (AX) and is radially inwardly opposed to a stator (320), wherein the outer circumferential surfaces (311A, 313A) of the rotor have reference planes (311B, 313B) corresponding to a part of the circumferential surface of a cylinder centered on the rotation axis (AX), and grooves (311C, 313C) adjacent to the reference planes (311B, 313B), one direction in the circumferential direction with respect to the rotation axis (AX) is defined as a first direction (RD), the direction opposite to the first direction (RD) in the circumferential direction is defined as a second direction, and in a cross section perpendicular to the rotation axis (AX), a circle hypothetically drawn as a circle including the reference planes (311B, 313B) is defined as a first circle (CC1). In the grooves (311C, 313C), the position closest to the rotation axis (AX) in the radial direction with respect to the rotation axis (AX) is defined as the first point (P1), and in the grooves (311C, 313C), the position located radially outside the first point (P1) and radially inside the first circle (CC1), and furthest from the first point (P1) in the first direction is defined as the second point (P2), and a line drawn virtually as a straight line passing through the rotation axis (AX) and the first point (P1) is defined as the first line (L1), and the surface of the grooves (311C, 313C) between the first point (P1) and the second point (P2) is defined as the first surface (SF1). The surface of the groove (311C, 313C) between the second point (P2) and the reference surfaces (311B, 313B) is defined as the second surface (SF2), and the grooves (311C, 313C) other than the first surface (SF1) and the second surface (SF2) are defined as the second surface (SF2),Let the plane of 313C) be the third plane (SF3), and let the point on the second plane (SF2) that is furthest from the second point (P2) in the second direction be the third point (P3), and let the point on the third plane (SF3) that is furthest from the first point (P1) in the second direction be the fourth point (P4), and let the intersection point of the first line (L1) and the first circle (CC1) be the fifth point (P5), and let the intersection point of the first line (L1) and the first line (L1) be the sixth point (P6), and let the line drawn virtually as a straight line connecting the first point (P1) and the second point (P2) be the second line (L2), Let the line hypothetically drawn connecting the first point (P1) and the fourth point (P4) be the third line (L3), and let the line hypothetically drawn connecting the second point (P2) and the third point (P3) be the fourth line (L4), let the angle between the first line (L1) and the second line (L2) be the first angle (θ1), let the angle between the first line (L1) and the third line (L3) be the second angle (θ2), let the angle between the second line (L2) and the fourth line (L4) be the third angle (θ3), let the distance between the first point (P1) and the sixth point (P6) be the first distance (A), and let the distance between the fifth point (P5) and the sixth point (P6) be the second distance (B), A rotor is provided in which, when the first angle (θ1) is greater than 0 degrees and less than 45 degrees, the first distance (A) is greater than the second distance (B); when the first angle (θ1) is 45 degrees, the first distance (A) and the second distance (B) are equal; when the first angle (θ1) is greater than 45 degrees and less than 90 degrees, the first distance (A) is less than the second distance (B); the second angle (θ2) is greater than 0 degrees and less than 90 degrees; and the third angle (θ3) is 90 degrees or greater and less than the angle obtained by subtracting the first angle from 180 degrees.

[0007] According to this embodiment, the rotor can generate vortices in the grooves provided on its outer surface as it rotates, thereby improving the cooling performance of the rotor.

[0008] Furthermore, in a second aspect of the present disclosure, building upon the first aspect described above, the present invention comprises an iron core (311) formed of a soft magnetic material and a permanent magnet (312) embedded in the iron core, wherein the outer surface may be the outer surface (311A) of the iron core.

[0009] Furthermore, in a third aspect of this disclosure, based on the second aspect described above, the groove (311C) may be provided radially outward from the permanent magnet (312).

[0010] Furthermore, in a fourth aspect of the present disclosure, based on the third aspect described above, when a second circle (CC2) is hypothetically drawn in the cross-section with the rotation axis (AX) as the center and passing through the outermost radial endpoint of the permanent magnet (312), the difference between the radius (R1) of the first circle (CC1) and the radius (R2) of the second circle (CC2) may be greater than the sum of the first distance (A) and the second distance (B), and less than twice the sum of the first distance (A) and the second distance (B).

[0011] Furthermore, in a fifth aspect of the present disclosure, building upon the first aspect described above, the present invention comprises: a cylindrical tube (313) centered on the rotation axis (AX); a permanent magnet (312) adjacent to the radially inner side of the tube (313); and an iron core (311) made of a soft magnetic material, adjacent to the radially inner side of the permanent magnet (312), wherein the outer surface is the outer surface (313A) of the tube, and the groove (313C) may be provided in the tube (313).

[0012] Furthermore, in a sixth aspect of the present disclosure, based on any one of the first to fifth aspects described above, the shape of the grooves (311C, 313C) may differ between two cross-sections located at different positions in the axial direction.

[0013] Furthermore, in a seventh aspect of this disclosure, the rotor may rotate in the first direction (RD), based on any one of the first to sixth aspects described above.

[0014] Furthermore, in an eighth aspect of the present disclosure, a fluid may flow between the outer circumferential surfaces (311A, 313A) and the stator (320), based on any one of the first to seventh aspects described above.

[0015] Furthermore, a ninth aspect of the present disclosure provides a rotating electric machine comprising a rotor (310) described in any one of the first to eighth aspects described above, and a stator (320).

[0016] Furthermore, in a tenth aspect of this disclosure, a refrigeration system is provided that includes the rotating electric machine (300) described in the ninth aspect above.

[0017] According to the above-described embodiment, the cooling performance of the rotor can be improved.

[0018] This is a diagram showing the configuration of an example of a refrigeration system. This is a diagram showing the configuration of an example of a compressor. This is a cross-sectional view showing a first example of a rotating electric machine. This is a perspective view showing a first example of a rotor. This is an enlarged cross-sectional view showing a second example of a rotor. This is a cross-sectional view schematically showing the shape of the grooves in a rotor according to a comparative example. This is a cross-sectional view schematically showing the shape of the grooves in a rotor according to an embodiment. This is a perspective view showing another example of a rotor. This is an enlarged cross-sectional view showing another example of a rotor. This is a cross-sectional view showing a first example of the detailed shape of the grooves. This is a cross-sectional view schematically showing the fluid flow in the grooves in a rotor according to a comparative example. This is a cross-sectional view schematically showing the fluid flow in the grooves in a rotor according to an embodiment. This is a cross-sectional view schematically showing the fluid flow in the grooves in a rotor according to a comparative example. This is a cross-sectional view schematically showing the fluid flow in the grooves in a rotor according to an embodiment. This is a cross-sectional view showing a second example of the detailed shape of the grooves. This is a cross-sectional view showing a third example of the detailed shape of the grooves. This is a cross-sectional view showing a second example of a rotating electric machine.

[0019] The embodiments will be described below with reference to the drawings.

[0020] [Refrigeration device] The refrigeration device 1 according to this embodiment will be described with reference to Figure 1.

[0021] Figure 1 shows an example of the configuration of a refrigeration device 1.

[0022] The refrigeration device 1 circulates a refrigerant through the refrigerant circuit RC and uses a compression refrigeration cycle to cool or heat the target liquid or gas.

[0023] Refrigeration device 1 is, for example, a chiller that cools a target liquid (cooled liquid) by heat exchange between a refrigerant and the target liquid using a compression refrigeration cycle. The cooled liquid is, for example, water or brine. Alternatively, refrigeration device 1 may be a water heater that generates hot water by heat exchange between a refrigerant and water using a compression refrigeration cycle. Alternatively, refrigeration device 1 may be an air conditioner that cools or heats a target space by heat exchange between a refrigerant and air. The following explanation will focus mainly on the case where refrigeration device 1 is a chiller.

[0024] As shown in Figure 1, the refrigeration system 1 includes, as components of the refrigerant circuit RC, refrigerant paths RL1 to RL4, a compressor 10, a heat exchanger 20, an expansion mechanism 30, and a heat exchanger 40.

[0025] Refrigerant pathways RL1 to RL4 are the paths through which the refrigerant flows. Refrigerant pathways RL1 to RL4 are, for example, metal pipes made of steel or other metal.

[0026] Refrigerant path RL1 connects the heat exchanger 40 to the suction port of the compressor 10. Refrigerant path RL2 connects the discharge port of the compressor 10 to the heat exchanger 20. Refrigerant path RL3 connects the heat exchanger 20 to the expansion mechanism 30. Refrigerant path RL4 connects the expansion mechanism 30 to the heat exchanger 40.

[0027] The compressor 10 compresses the low-pressure refrigerant flowing in from the refrigerant path RL1 and discharges the high-pressure refrigerant into the refrigerant path RL2.

[0028] The heat exchanger 20 performs heat exchange between a refrigerant flowing through its interior and an external heat transfer medium (for example, cooling water).

[0029] The heat exchanger 20 is a so-called condenser, which cools the high-temperature and high-pressure refrigerant, compressed by the compressor 10 and flowing in from the refrigerant path RL2, through heat exchange with an external heat transfer medium, thereby condensing it and releasing the high-pressure liquid refrigerant into the refrigerant path RL3.

[0030] The expansion mechanism 30 expands the high-pressure liquid refrigerant, causing the low-pressure gas-liquid mixture of refrigerant to flow out. The expansion mechanism 30 is, for example, an expansion valve or an orifice.

[0031] The expansion mechanism 30 expands the high-pressure liquid refrigerant that flows in from the refrigerant path RL3 and has passed through the heat exchanger 20, causing the low-pressure gas-liquid mixed refrigerant to flow out into the refrigerant path RL4.

[0032] The heat exchanger 40 performs heat exchange between the refrigerant flowing through its interior and the external liquid to be cooled.

[0033] The heat exchanger 40 is a so-called evaporator, and by absorbing heat from the liquid to be cooled, it heats the low-pressure gas-liquid mixture of refrigerant that flows in from the refrigerant path RL4 and has been expanded by the expansion mechanism 30, thereby evaporating it and causing the low-pressure gaseous refrigerant to flow out into the refrigerant path RL1. In this way, the refrigeration system 1 can cool the liquid to be cooled.

[0034] [Compressor] The compressor 10 according to this embodiment will be described with reference to Figure 2.

[0035] Figure 2 shows an example configuration of a compressor 10.

[0036] Figure 2 shows a cross-sectional view in a plan view that includes the rotation axis AX of the rotating shaft 250, so that the contents inside the casing 100 are exposed.

[0037] Hereinafter, the axial, radial, and circumferential directions, with respect to the rotational axis AX, may simply be referred to as "axial direction," "radial direction," and "circumferential direction," respectively.

[0038] Furthermore, "axial direction" refers to the direction along the rotation axis AX of the rotation axis 250 (i.e., the parallel direction).

[0039] As shown in Figure 2, in this example, the compressor 10 is a centrifugal compressor.

[0040] The number of stages of the compressor 10 is, for example, one stage (single stage) as shown in FIG. 2. Also, the number of stages of the compressor 10 may be two or more multi-stages. In the multi-stage compressor 10, a plurality of compression parts including the impeller 200 are provided in series.

[0041] The compressor 10 includes a casing 100, an impeller 200, a rotating shaft 250, a rotating electric machine 300, a radial magnetic bearing 400, a thrust magnetic bearing 500, and a touchdown bearing 600.

[0042] The casing (also referred to as "housing") 100 is a housing for accommodating and attaching the components of the compressor 10 inside.

[0043] The impeller 200 is accommodated in an impeller chamber 110 formed inside the casing 100.

[0044] The impeller 200 is attached to the rotating shaft 250 and rotates about the rotation axis AX of the rotating shaft 250. The impeller 200 is formed such that the outer diameter in the meridional plane increases from one end in its axial direction (in this example, the right end in the figure) to the other end (in this example, the left end in the figure). The impeller 200 causes the refrigerant flowing axially from the suction pipe 120 to flow out radially outward at the other end in its axial direction at the circumferential center portion at one end in its axial direction. A diffuser 111 is provided on the radially outer side at the radially outer end of the impeller 200. In the diffuser 111, the dynamic pressure (i.e., kinetic energy) of the refrigerant flowing out from the impeller 200 is converted into static pressure (i.e., pressure energy), and the compressed refrigerant flows out from the diffuser 111 to the discharge pipe 130.

[0045] The rotating electric machine (also referred to as "motor" or "rotary electric motor", etc.) 300 is accommodated in a motor chamber 140 formed inside the casing 100.

[0046] The rotating electric machine 300 rotationally drives the impeller 200 using electric power supplied from the outside. The rotating electric machine 300 is, for example, a permanent magnet synchronous motor. The rotating electric machine 300 has a radial gap type and an inner rotor type, and includes a rotor 310 attached to the rotating shaft 250 and a stator 320 disposed on the outer side in the radial direction of the rotor 310 and fixed to the inner peripheral surface of the motor chamber 140 in the casing 100.

[0047] In this example, the rotating shaft 250 has a hollow structure, and the hollow portion 270 of the rotating shaft 250 has an opening 271 for taking in fluid from the outside of the casing 100 at one axial end and an opening 272 for allowing the fluid to flow into the motor chamber 140 at the other axial end. The fluid is, for example, a refrigerant. Also, the fluid may be other types of gases or liquids.

[0048] The fluid flowing into the motor chamber 140 through the hollow portion 270 of the rotating shaft 250 passes through the gap (air gap) between the rotor 310 and the stator 320 from one axial end side to the other end side due to the pressure difference. Thereby, the rotating electric machine 300 is cooled by the fluid flowing into the motor chamber 140.

[0049] The fluid that has passed through the gap between the rotor 310 and the stator 320 is discharged to the outside of the casing 100 through the discharge port 150 provided in the casing 100.

[0050] The radial magnetic bearing 400 supports the radial load of the rotating shaft 250 in a non-contact manner by electromagnetic force. Two radial magnetic bearings 400 are provided and are respectively fixed to the inner surface of the casing 100. The two radial magnetic bearings 400 are arranged so as to be adjacent to both ends of the rotating electric machine 300 in the axial direction.

[0051] The thrust magnetic bearing 500 supports the thrust load of the rotating shaft 250 non-contact by electromagnetic force. The thrust magnetic bearing 500 includes a pair of electromagnets 510, each fixed to the inner surface of the casing 100. The pair of electromagnets 510 are positioned adjacent to each of the axial ends of a disc-shaped collar 260, which is provided on the rotating shaft 250 and is centered on the rotation axis AX. The collar 260 (also called the "thrust disk") is made of a magnetic material, and the thrust magnetic bearing 500 maintains the position of the rotating shaft 250, which is integrated with the collar 260, non-contact by the magnetic attraction force of the pair of electromagnets 510 to the collar 260.

[0052] The touchdown bearing 600 is provided to suppress contact between the rotating shaft 250 and the radial magnetic bearing 400, and between the collar 260 and the electromagnet 510 of the thrust magnetic bearing 500. The touchdown bearing 600 is, for example, mainly composed of angular contact ball bearings.

[0053] [First Example of a Rotating Electric Machine] Referring to Figure 3, a first example of a rotating electric machine 300 according to this embodiment will be described.

[0054] Figure 3 is a cross-sectional view showing a first example of the rotating electric machine 300. Specifically, Figure 3 is a cross-sectional view of a first example of the rotating electric machine 300, taken from a plane perpendicular to the rotation axis AX.

[0055] As shown in Figure 3, the rotating electric machine 300 includes a rotor 310 and a stator 320 that face each other radially with an air gap between them, as described above.

[0056] The rotor (also called the "rotor") 310 is a field element and is positioned radially inward, facing the stator 320 in the radial direction. It is mounted on the rotating shaft 250 and can rotate around the rotational axis AX of the rotating shaft 250. The rotor 310 includes a rotor core 311 and a plurality of permanent magnets 312.

[0057] The rotor core (also called the "rotor core") 311 is formed from a soft magnetic material such as electromagnetic steel sheet or compacted magnetic core, and functions as a magnetic path for the magnetic field caused by the current flowing through the windings 322 of the stator 320 and the magnetic field of the permanent magnet 312.

[0058] The rotor core 311 has a cylindrical shape centered on the rotation axis AX, and is provided with a through hole that penetrates axially, also centered on the rotation axis AX. The rotation shaft 250 is inserted through and fixed in the through hole. As a result, the rotor 310 can rotate together with the rotation shaft 250.

[0059] The permanent magnet 312 generates a magnetic field that links with the winding 322 of the stator 320. The permanent magnet 312 is, for example, an Alnico magnet or a neodymium magnet.

[0060] Multiple (24 in this example) permanent magnets 312 are arranged at equal intervals in the circumferential direction on the rotor core 311. In this example, the multiple permanent magnets 312 are embedded inside the rotor core 311. That is, in this example, the rotating electric machine 300 is a so-called embedded magnet type (IPM: Interior Permanent Magnet) rotating electric machine. Specifically, holes (also called "magnet slots") are formed in the rotor core 311 along the axial direction, and the permanent magnets 312 are embedded inside the rotor core 311 by being inserted into these holes.

[0061] The permanent magnet 312 is magnetized so as to be approximately aligned with the radial direction at the circumferential position where it is positioned. The term "approximately" in relation to shape, arrangement, etc., is intended to allow for manufacturing errors (tolerances), and is used in the same sense hereafter.

[0062] The number of poles of the rotor 310 is an even number of two or more, and is set as appropriate. For example, if the rotor 310 has four poles, in this case the 24 permanent magnets 312 are divided into four permanent magnet groups, each consisting of six adjacent permanent magnets 312. One permanent magnet group is arranged so that its polarity is different from other permanent magnet groups adjacent to it in the circumferential direction. For example, if the six permanent magnets 312 in one permanent magnet group are arranged so that their radially outer sides are north poles, then the six permanent magnets 312 in other permanent magnet groups adjacent to that group in the circumferential direction are arranged so that their radially outer sides are south poles. The number of poles of the rotor 310 may be two, or it may be an even number of six or more.

[0063] In this example, the permanent magnet 312 is embedded very close to the outer surface of the rotor core 311. Therefore, a relatively large gap is maintained between the rotor 310 and the stator 320. If the gap is made relatively small under the condition that the permanent magnet 312 is embedded very close to the outer surface of the rotor core 311, the iron loss in the rotor core 311 due to harmonics caused by the slots where the windings 322 are arranged, the carrier frequency, and the eddy current loss in the permanent magnet 312 will increase when the rotating electric machine 300 rotates at high speed.

[0064] The stator (also called the "stator") 320 is the armature, positioned radially outward from the rotor 310 so as to face it radially, and fixed to the casing 100. The stator 320 includes a stator core 321 and a plurality of windings 322.

[0065] The stator core (also called the "stator core") 321 is formed from a soft magnetic material such as electromagnetic steel sheet or compacted magnetic core, and functions as a magnetic path for the magnetic flux caused by the current flowing through the windings 322 and the magnetic flux of the permanent magnets 312 of the rotor 310. The stator core 321 includes a back yoke portion 321A having a substantially cylindrical shape centered on the rotation axis AX, and a plurality of teeth portions 321B that protrude radially inward from the inner circumferential surface of the back yoke portion 321A.

[0066] Multiple teeth portions 321B are arranged at approximately equal intervals in the circumferential direction on the inner circumference side of the back yoke portion 321A.

[0067] Multiple windings (also called "coils") 322 are wound around each of the multiple tooth sections 321B by concentrated winding. An insulating material, such as an insulating film made of PET (Polyethylene Terephthalate), is interposed between the windings 322 and the tooth sections 321B.

[0068] For example, the rotating electric machine 300 is driven by a three-phase alternating current consisting of U-phase, V-phase, and W-phase power. In this case, the multiple windings 322 include an equal number of U-phase, V-phase, and W-phase windings 322. Alternatively, the rotating electric machine 300 may be driven by a four-phase or more alternating current.

[0069] Furthermore, the winding 322 may be wound in a distributed winding manner so as to span two or more teeth 321B. Also, the number of slots in this example (Figure 3), i.e., the number of windings 322, is just one example and may be fewer or more than this example. Similarly, the number of poles in this example (4 poles) is just one example and may be fewer or more than this example.

[0070] [First Example of Rotor] In addition to Figure 3, a first example of the rotor 310 according to this embodiment will be described with reference to Figures 4 and 5.

[0071] Figure 4 is a perspective view showing a first example of the rotor 310. Figure 5 is an enlarged cross-sectional view showing a first example of the rotor 310. Specifically, Figure 5 is an enlarged cross-sectional view showing the structure near the outer circumferential surface 311A ​​of the rotor 310.

[0072] As shown in Figures 4 and 5, in this example, the rotor core 311 is exposed on the outermost radial surface of the rotor 310, and the outer surface of the rotor 310 is the outer surface 311A ​​of the rotor core 311.

[0073] The outer circumferential surface 311A ​​of the rotor core 311 includes a reference surface 311B and a groove 311C.

[0074] The reference surface 311B is a surface that extends in the circumferential and axial directions with an outer diameter that is approximately constant, centered on the rotation axis AX, and corresponds to a part of the circumferential surface (side surface) of a cylinder centered on the rotation axis AX.

[0075] The groove 311C is a recess formed on a surface radially inward from the reference surface 311B. For example, as shown in Figure 4, the groove 311C is formed over the entire area spanning both ends of the rotor core 311 in the axial direction. Alternatively, the groove 311C may be formed over a portion of the area between the two ends of the rotor core 311 in the axial direction.

[0076] In this example, as shown in Figure 4, the shape of the groove 311C is the same throughout the entire axial range in which the groove 311C is provided.

[0077] Furthermore, multiple grooves 311C are provided in the circumferential direction at predetermined intervals. In the circumferential direction, the spacing between adjacent grooves 311C may all be the same (i.e., equally spaced) or they may not all be the same (i.e., unequally spaced).

[0078] For example, as shown in Figure 5, the grooves 311C are arranged so as to overlap with the area where the permanent magnets 312 are placed in the circumferential direction, and are located radially outward from the permanent magnets 312. In this example, the same number of grooves 311C as the number of permanent magnets 312 are provided on the outer circumferential surface 311A ​​of the rotor core 311.

[0079] [Overview of Groove Shape] Referring to Figures 6 and 7, an overview of the shape of the groove 311C according to this embodiment will be described.

[0080] Figure 6 is a schematic cross-sectional view showing the shape of the groove 311Cc in the rotor 310c according to a comparative example. Figure 7 is a schematic cross-sectional view showing the shape of the groove 311C in the rotor 310 according to the embodiment.

[0081] In the following description, components other than those differing between the rotor 310 according to the embodiment and the rotor 310c according to the comparative example will be denoted by the same reference numerals for convenience. The same applies to the relationship between the rotor 310 according to the embodiment and the rotors 310c1 to 310c4 according to the comparative example described later.

[0082] In Figures 6 and 7, the flow of fluid around the rotor 310c, 310 during rotation is represented by thick arrows.

[0083] As shown in Figure 6, the outer circumferential surface of the rotor core 311c in the comparative example rotor 310c includes a reference surface 311B and a groove 311Cc0.

[0084] The groove 311Cc0 includes surfaces SF1 and SF3.

[0085] Surface SF1 is a surface that, in a cross section perpendicular to the rotation axis AX, is inclined radially in the rotation direction RD of the rotor 310c, as viewed from point P1, which corresponds to the innermost position in the radial direction of the groove 311Cc0. In this comparative example, surface SF1 connects point P1 and the reference surface 311B, which is located in the rotation direction RD as viewed from point P1, in a cross section perpendicular to the rotation axis AX.

[0086] Surface SF3 is a surface that, in a cross section perpendicular to the rotation axis AX, is inclined in the opposite direction to the rotation direction RD of the rotor 310c with respect to the radial direction, as viewed from point P1. In this comparative example, surface SF3 connects point P1 and the reference surface 311B, which is in the opposite direction to the rotation direction RD as viewed from point P1, in a cross section perpendicular to the rotation axis AX.

[0087] As shown in Figure 6, when the rotor 310c rotates in the rotational direction RD, the fluid flows in the opposite direction to the rotational direction RD along the reference surface 311B as seen from the rotor 310c. As a result, a portion of the fluid passing through the circumferential area where the groove 311Cc0 is provided is drawn into the groove 311Cc0, and vortices are formed within the groove 311Cc0. Consequently, the rotor 310c can be cooled by the heat dissipation from the surfaces SF1 and SF3 of the groove 311Cc0 to the fluid by the vortices.

[0088] However, the vortices formed in the groove 311Cc0 may separate near the connection between the surface SF3 and the reference surface 311B, resulting in the accumulation of high-temperature fluid and potentially reducing the cooling performance of the rotor 310c (see dashed box in the figure).

[0089] In contrast, as shown in Figure 7, in this embodiment, the groove 311C includes surfaces SF1 to SF3.

[0090] Unlike the comparative example, surface SF1 connects point P1 to a position radially inward from the reference surface 311B in a cross-section perpendicular to the rotation axis AX.

[0091] Surface SF2 connects the radially outer end of surface SF1 to the reference surface 311B in a cross section perpendicular to the rotation axis AX. The inclination of surface SF2 is different from that of surface SF1. Specifically, in a cross section perpendicular to the rotation axis AX, surface SF2 is positioned such that, when viewed from surface SF1, it is tilted in the opposite direction to the rotation direction RD, with one radially outer end of surface SF1 as the pivot point. This suppresses vortex separation, as shown in Figure 7 (see dashed box in the figure). Therefore, the cooling performance of the rotor 310 can be improved. Thus, for example, demagnetization of the permanent magnet 312 due to heat can be suppressed.

[0092] For example, as described above, if a relatively large gap is secured between the rotor 310 and the stator 320, the fluid velocity passing through the gap from one end to the other in the axial direction may be relatively low. As a result, the cooling performance of the rotor 310 may decrease.

[0093] In contrast, in this embodiment, the cooling performance of the rotor 310 can be improved by the effect of the vortices formed in the groove 311C. Furthermore, in this embodiment, the action of the surface SF2 of the groove 311C suppresses vortex separation and prevents high-temperature fluid from accumulating in the groove 311C. Therefore, the cooling performance of the rotor 310 can be further improved. Thus, for example, even when a relatively large gap is secured between the rotor 310 and the stator 320, the cooling performance of the rotor 310 can be ensured.

[0094] [Second example of rotor] A second example of the rotor 310 will be described with reference to Figures 3, 8, and 9, in addition to Figure 3.

[0095] In this example, the same or corresponding components as in the first example of the rotor 310 described above (Figures 4 and 5) are denoted by the same reference numerals, and the explanation focuses on the parts that differ from the first example, while the explanation of parts that are the same or corresponding to the first example may be omitted.

[0096] Figure 8 is a perspective view showing a second example of the rotor 310. Figure 9 is an enlarged cross-sectional view showing a second example of the rotor 310. Specifically, Figure 9 is an enlarged cross-sectional view showing the structure near the outer circumferential surface 311A ​​of the rotor 310. Figure 9 includes Figure 9A, which represents a cross-sectional view corresponding to the cross-section CS1 in Figure 8, and Figure 9B, which represents a cross-sectional view corresponding to the cross-section CS2 in Figure 8.

[0097] As shown in Figures 8 and 9, this example differs from the first example described above in that the shape of the groove 311C changes in the axial direction.

[0098] Specifically, in the axial direction, the shape of the groove 311C in the range between one end and the intermediate position (see Figure 9A) is different from the shape of the groove 311C in the range between the other end and the intermediate position (see Figure 9B).

[0099] This allows for the individual optimization of the groove 311C on one end of the axial direction and the groove 311C on the other end of the axial direction, taking into consideration, for example, the axial flow of the fluid flowing through the gap between the rotor 310 and the stator 320. As a result, the cooling performance of the rotor 310 can be further improved.

[0100] Furthermore, the shape of the groove 311C may change in three or more stages, rather than just two, in the axial direction. Alternatively, the shape of the groove 311C may change continuously in the axial direction.

[0101] [First example of detailed groove shape] The first example of the detailed shape of groove 311C will be described with reference to Figures 10 to 15.

[0102] Figure 10 is a diagram showing a first example of the detailed shape of groove 311C. Figure 11 is a schematic cross-sectional view showing the fluid flow in grooves 311Cc1 and 311Cc2 in rotors 310c1 and 310c2 according to a comparative example. Figure 12 is a schematic cross-sectional view showing the fluid flow in groove 311C in rotor 310 according to the embodiment. Figure 13 is a schematic cross-sectional view showing the fluid flow in grooves 311Cc3 and 311Cc4 in rotors 310c3 and 310c4 according to a comparative example. Figure 14 is a schematic cross-sectional view showing the fluid flow in groove 311C in rotor 310 according to the embodiment.

[0103] Specifically, Figure 11 includes Figure 11A, which schematically represents the fluid flow in groove 311Cc1 in rotor 310c1 according to the comparative example, and Figure 11B, which schematically represents the fluid flow in groove 311Cc2 in rotor 310c2 according to the comparative example. Groove 311Cc1 corresponds to the case where angle θ1, described later, is greater than 0 degrees and less than 45 degrees (0° < θ1 < 45°), and angle θ3, described later, is less than 90 degrees (θ3 < 90°). Groove 311Cc2 corresponds to the case where angle θ1, described later, is greater than 0 degrees and less than 45 degrees (0° < θ1 < 45°), and distance B, described later, is greater than or equal to distance A, described later. Furthermore, Figure 13 includes Figure 13A, which schematically represents the fluid flow in the groove 311Cc3 of the rotor 310c3 according to the comparative example, and Figure 13B, which schematically represents the fluid flow in the groove 311Cc4 of the rotor 310c4 according to the comparative example.

[0104] In Figures 11 to 14, the flow of fluid around the rotor 310c1 to 310c4 and 310 during rotation is represented by thick arrows. Furthermore, in a cross-section perpendicular to the rotation axis AX, the various surfaces of the rotor 310 (for example, the surface of groove 311C) are represented as the intersection lines of a plane perpendicular to the rotation axis AX and the symmetrical surface.

[0105] In this example, as shown in Figure 10, the groove 311C includes surfaces SF1 to SF3, and the shape of the groove 311C is defined by a circle CC1, points P1 to P6, lines L1 to L4, angles θ1 to θ3, and distances A and B.

[0106] Circle CC1 is a hypothetical circle drawn in a cross section perpendicular to the axis of rotation AX, including the reference plane 311B. Point P1 is, as described above, a hypothetical point in the groove 311C in a cross section perpendicular to the axis of rotation AX, corresponding to the innermost radial position (i.e., the position closest to the axis of rotation AX in the radial direction). Point P2 is a hypothetical point in the groove 311C in a cross section perpendicular to the axis of rotation AX, located radially outward from point P1 and furthest from point P1 in the rotational direction RD. Line L1 is a hypothetical straight line drawn in a cross section perpendicular to the axis of rotation AX, passing through the axis of rotation AX and point P1. Surface SF1 is the surface of the groove 311C between point P1 and point P2 in a cross section perpendicular to the axis of rotation AX. In this example, surface SF1 is represented as a straight line connecting points P1 and P2 in a cross section perpendicular to the axis of rotation AX. Surface SF2 is the surface of the groove between point P2 and the reference surface 311B in a cross section perpendicular to the axis of rotation AX. In this example, surface SF2 is represented as a straight line connecting point P2 and the reference surface 311B in a cross section perpendicular to the axis of rotation AX. Surface SF3 is the surface of the groove 311C other than surfaces SF1 and SF2 in a cross section perpendicular to the axis of rotation AX, specifically the surface of the groove 311C between point P1 and the reference surface 311B which is in the opposite direction to the rotation direction RD when viewed from point P1. In this example, surface SF3 is represented as a straight line connecting point P1 and the reference surface 311B which is in the opposite direction to the rotation direction RD when viewed from point P1 in a cross section perpendicular to the axis of rotation AX. Point P3 is a hypothetical point on plane SF2, furthest from point P2 in the opposite direction of rotation RD, in a cross section perpendicular to the axis of rotation AX. In this example, point P3 is the intersection of plane SF2, which is represented as a straight line, and circle CC1, in a cross section perpendicular to the axis of rotation AX. Point P4 is a point on plane SF3, furthest from point P1 in the opposite direction of rotation RD, in a cross section perpendicular to the axis of rotation AX. Point P5 is the intersection of line L1 and circle CC1, in a cross section perpendicular to the axis of rotation AX, and is located radially outside of point P1. Point P6 is the intersection of a hypothetical perpendicular line drawn from point P2 to line L1 and line L1. Line L2 is a straight line (specifically, a line segment) connecting points P1 and P2. Line L3 is a straight line (specifically, a line segment) connecting points P1 and P4.Line L4 is a straight line (specifically, a line segment) connecting points P2 and P3. Angle θ1 is the angle between line L1 and line L2. Angle θ2 is the angle between line L1 and line L3. Angle θ3 is the angle between line L2 and line L4. Distance A is the distance between point P1 and point P6. Distance B is the distance between point P5 and point P6.

[0107] In this example, point P3 is located on the reference plane 311B, but point P3 may also be positioned radially inward from the reference plane 311B.

[0108] The groove 311C is provided such that any of the following conditions (1) to (3) are satisfied with respect to the angle θ1 and distances A and B.

[0109] (When 0° < θ1 < 45°) A > B ... (1) (When θ1 = 45°) A = B ... (2) (When 45° < θ < 90°) A < B ... (3)

[0110] Furthermore, in this example, the groove 311C is provided such that both conditions of equations (4) and (5) are satisfied for angles θ2 and θ3.

[0111] 0°<θ2<90°...(4) 90°≦θ3<180°-θ1...(5)

[0112] For example, Figure 11A is a comparative example where the angle θ1 is greater than 0° and less than 45° (0° < θ1 < 45°), and the angle θ3 is less than 90° (θ3 < 90°), so the conditions of equation (5) are not met. Therefore, as shown in Figure 11A, vortices are separated near the connection point of surfaces SF1 and SF2 (see dashed box in the figure). As a result, high-temperature fluid may accumulate, potentially reducing the cooling performance of the rotor 310c1.

[0113] Furthermore, for example, Figure 11B is a comparative example where, under the condition that the angle θ1 is greater than 0° and less than 45° (0° < θ1 < 45°), distance A is less than or equal to distance B (A ≤ B), and none of the conditions in equations (1) to (3) above are met. Therefore, as shown in Figure 11B, vortices are separated adjacent to each other over a wide area from surface SF1 to surface SF2 (see dashed box in the figure). As a result, high-temperature fluid may accumulate, potentially reducing the cooling performance of the rotor 310c2.

[0114] In contrast, the groove 311C in Figure 12 satisfies the conditions of equation (1), as well as equations (4) and (5) from the above-mentioned equations (1) to (3). Therefore, as shown in Figure 12, vortex separation can be suppressed in the area adjacent to surfaces SF1 and SF2, including the vicinity of the connection point of surfaces SF1 and SF2 (see dashed frame). As a result, the retention of high-temperature fluid in the groove 311C can be suppressed, and the cooling performance of the rotor 310 can be improved.

[0115] Furthermore, for example, Figure 13A is a comparative example where angle θ1 is greater than 45° and less than 90° (45° < θ1 < 90°), and angle θ3 is less than 90° (θ3 < 90°), so the conditions of equation (5) are not met. Therefore, as shown in Figure 13A, vortices are separated near the connection point of surfaces SF1 and SF2 (see dashed line frame in the figure). As a result, high-temperature fluid may accumulate, potentially reducing the cooling performance of the rotor 310c3.

[0116] Furthermore, for example, Figure 13B is a comparative example where, under the condition that angle θ1 is greater than 45° and less than 90° (45° < θ1 < 90°), distance A is greater than distance B (A > B), and none of the conditions in equations (1) to (3) above are met. Therefore, as shown in Figure 13B, vortices are separated near the connection point of surfaces SF1 and SF2 (see dashed box in the figure). As a result, high-temperature fluid may accumulate, potentially reducing the cooling performance of the rotor 310c4.

[0117] In contrast, the groove 311C in Figure 14 satisfies the conditions of equation (3), as well as equations (4) and (5) from (1) to (3) above. Therefore, as shown in Figure 12, vortex separation can be suppressed in the area adjacent to surfaces SF1 and SF2, including the vicinity of the connection point of surfaces SF1 and SF2 (see dashed frame). As a result, the retention of high-temperature fluid in the groove 311C can be suppressed, and the cooling performance of the rotor 310 can be improved.

[0118] Furthermore, in this example, assuming the radius R1 of circle CC1 and the radius R2 of a hypothetical circle CC2 passing through the outermost radial endpoint of the permanent magnet 312, the groove 311C satisfies the following condition (6) for distances A and B.

[0119] A+B<R1-R2<2・(A+B)...(6)

[0120] This allows the groove 311C to be appropriately positioned radially outward from the permanent magnet 312. As a result, the circumferential range in which the permanent magnet 312 is positioned and the circumferential range in which the groove 311C is positioned can be made to overlap, thereby improving the cooling performance of the permanent magnet 312 in the rotor 310.

[0121] [Second example of detailed groove shape] A second example of the detailed shape of groove 311C will be described with reference to Figure 15.

[0122] In the following, components identical to or corresponding to the first example of the detailed shape of groove 311C described above will be denoted by the same reference numerals. The explanation will focus on the parts that differ from the first example, and the explanation of parts that are the same as or corresponding to the first example may be omitted. The same correspondence will be applied to the third example of the detailed shape of groove 311C described later, in relation to the first and second examples.

[0123] Figure 15 shows a second example of the detailed shape of groove 311C.

[0124] As shown in Figure 15, the detailed shape of the groove 311C in this example differs from the first example described above in that the shapes of surfaces SF1 to SF3 are different in a cross section perpendicular to the rotation axis AX.

[0125] In a cross-section perpendicular to the axis of rotation AX, planes SF1 and SF2 are continuously connected in a curved manner near point P2.

[0126] Furthermore, in a cross-section perpendicular to the rotation axis AX, surfaces SF1 and SF3 are continuously connected in a curved manner near point P1.

[0127] Furthermore, in a cross-section perpendicular to the rotation axis AX, the surface SF2 and the reference surface 311B are connected in a curved and continuous manner near point P3.

[0128] Furthermore, in a cross-section perpendicular to the rotation axis AX, the surface SF3 and the reference surface 311B are continuously connected in a curved manner near point P4.

[0129] In this example, the groove 311C is provided such that any of the conditions in equations (1) to (3), as well as the conditions in equations (4) and (5), are satisfied, similar to the first example described above. This suppresses the separation of vortices generated in the groove 311C as the rotor 310 rotates, thereby improving the cooling performance of the rotor 310.

[0130] [Third example of detailed groove shape] A third example of the detailed shape of groove 311C will be described with reference to Figure 16.

[0131] Figure 16 shows a third example of the detailed shape of groove 311C.

[0132] As shown in Figure 16, the detailed shape of the groove 311C in this example differs from the first and second examples described above in that the shapes of surfaces SF1 to SF3 are different in a cross-section perpendicular to the rotation axis AX.

[0133] In a cross-section perpendicular to the axis of rotation AX, surface SF1 connects points P1 and P2 with a concave curve.

[0134] In a cross-section perpendicular to the axis of rotation AX, surface SF2 connects points P2 and P3 with a concave curve.

[0135] In a cross-section perpendicular to the axis of rotation AX, surface SF3 connects points P1 and P4 with a concave curve.

[0136] In this example, the groove 311C is provided such that any of the conditions in equations (1) to (3), as well as the conditions in equations (4) and (5), are satisfied, similar to the first example described above. This suppresses the separation of vortices generated in the groove 311C as the rotor 310 rotates, thereby improving the cooling performance of the rotor 310.

[0137] [Other examples of detailed groove shapes] Other examples of detailed groove shapes for groove 311C are described below.

[0138] The groove 311C may have a different detailed shape from the first to third examples described above, as long as any of the conditions in equations (1) to (3) above, as well as the conditions in equations (4) and (5), are met.

[0139] For example, the groove 311C may have a detailed shape that combines the second and third examples described above.

[0140] [Second Example of a Rotating Electric Machine] A second example of a rotating electric machine 300 will be described with reference to Figure 17.

[0141] In the following examples, we will focus on explaining the differences from the first example of the rotating electric machine 300 described above (Figure 3), and we may omit explanations of parts that are the same as or correspond to the first example.

[0142] Figure 17 shows a second example of the rotating electric machine 300. Figure 17 is a cross-sectional view of the second example of the rotating electric machine 300, taken from a plane perpendicular to the rotation axis AX.

[0143] In this example, the stator 320 may be the same as in the first example of the rotating electric machine 300 described above. For convenience, the stator 320 is omitted from Figure 17. Also, in this example, the rotor 310 of the rotating electric machine 300 rotates counterclockwise in the figure.

[0144] As shown in Figure 17, the configuration of the rotor 310 of the rotating electric machine 300 in this example differs from that of the first example described above.

[0145] The rotor 310 includes a rotor core 311, a plurality of permanent magnets 312, and a protective tube 313.

[0146] The rotor core 311 has a radially outer surface (i.e., an outer circumferential surface) on which the permanent magnets 312 are arranged. In other words, in this example, the rotating electric machine 300 is a so-called surface permanent magnet (SPM) rotating electric machine.

[0147] For example, as shown in Figure 17, the rotor 310 has the shape of a rectangular prism with a square cross-section perpendicular to the rotation axis AX, and permanent magnets 312 are arranged on each of the four sides of the rectangular prism.

[0148] Multiple permanent magnets 312 are arranged on the surface of the rotor core 311 and are spaced equally in the circumferential direction. The permanent magnets 312 are joined together, for example, by an adhesive.

[0149] For example, as shown in Figure 17, the permanent magnet 312 has a plane that contacts the side surface of the rotor core 311, and a curved surface that, when viewed along the axial direction, appears as a circular arc with a constant outer diameter centered on the rotation axis AX and contacts the inner circumferential surface of the protective tube 313.

[0150] The protective tube 313 is a tubular member centered on the rotation axis AX, and houses the rotor core 311 and a plurality of permanent magnets 312 in its radially inner hollow portion. This allows the protective tube 313 to hold the permanent magnets 312 exposed on the surface of the rotor core 311 radially inward. The protective tube 313 is joined to the permanent magnets 312, for example, by interference fit.

[0151] In this example, since the protective tube 313 is located on the outermost radial circumference of the rotor 310, the outer surface of the rotor 310 is the outer surface 313A of the protective tube 313.

[0152] As shown in Figure 17, the outer surface 313A of the protective tube 313 includes a reference surface 313B and a groove 313C.

[0153] The reference surface 313B is a surface that extends in the circumferential and axial directions with an outer diameter that is approximately constant, centered on the rotation axis AX, and corresponds to a part of the circumferential surface (side surface) of a cylinder centered on the rotation axis AX.

[0154] The groove 313C is a recess formed on a surface radially inward from the reference surface 313B. For example, the groove 313C is formed over the entire area spanning both ends of the protective tube 313 in the axial direction. Alternatively, the groove 313C may be formed over a portion of the area between the two ends of the protective tube 313 in the axial direction.

[0155] Furthermore, multiple grooves 313C are provided in the circumferential direction at predetermined intervals. In the circumferential direction, the spacing between adjacent grooves 313C may all be the same (i.e., equally spaced) or they may not all be the same (i.e., unequally spaced).

[0156] Groove 313C provides the same function and effect as groove 311C in the first example of the rotating electric machine 300 described above.

[0157] The groove 313C has the same shape overall in the axial direction, for example, similar to the groove 311C in the first example of the rotor 310 described above (Figures 4 and 5). Alternatively, the groove 313C may change shape in a stepwise or continuous manner in the axial direction, for example, similar to the groove 311C in the second example of the rotor 310 described above (Figures 8 and 9).

[0158] The groove 313C is provided such that the conditions defined in the same way as those based on the above-described conditions (1) to (5) are met, as in the first to third examples of the detailed shape of the groove 311C. This makes it possible to further improve the cooling performance of the rotor 310, as in the first example of the rotating electric machine 300 described above, and to cool the rotor 310 more efficiently.

[0159] Furthermore, the groove 313C may have any detailed shape, as is the case with the groove 311C described above, as long as the above conditions are met.

[0160] [Operation] The operation of the rotor, rotating electric machine, and refrigeration device according to this embodiment will be described below.

[0161] In the first aspect of this embodiment, the rotor is a rotor that faces radially inward from the stator and is rotatable about a rotation axis. The rotor is, for example, the rotor 310 described above. The stator is, for example, the stator 320 described above. The rotation axis is, for example, the rotation axis AX described above. Specifically, the outer circumferential surface of the rotor has a reference surface corresponding to a part of the circumferential surface of a cylinder centered on the rotation axis, and a groove adjacent to the reference surface. The outer circumferential surface is, for example, the outer circumferential surface 311A ​​or the outer circumferential surface 313A described above. The reference surface is, for example, the reference surface 311B or the reference surface 313B described above. The groove is, for example, the groove 311C or the groove 313C described above. Furthermore, one direction in the circumferential direction with respect to the rotation axis is defined as the first direction. The first direction is, for example, the rotation direction RD described above. Furthermore, the direction opposite to the first direction in the circumferential direction is defined as the second direction. The second direction is, for example, the opposite direction to the rotation direction RD described above. Furthermore, in a cross section perpendicular to the rotation axis, a circle drawn virtually as a circle including the reference plane is defined as the first circle. The first circle is, for example, the circle CC1 described above. Furthermore, in a cross section perpendicular to the rotation axis, the position in the groove closest to the rotation axis in the radial direction with respect to the rotation axis is defined as the first point. The first point is, for example, the point P1 described above. Furthermore, in a cross section perpendicular to the rotation axis, the position in the groove located radially outward from the first point and radially inward from the first circle, and furthest from the first point in the first direction, is defined as the second point. The second point is, for example, the point P2 described above. Furthermore, in a cross section perpendicular to the rotation axis, a line drawn virtually as a straight line passing through the rotation axis and the first point is defined as the first line. The first line is, for example, the line L1 described above. Furthermore, in a cross section perpendicular to the axis of rotation, the surface of the groove between the first point and the second point is defined as the first surface. The first surface is, for example, the surface SF1 described above. Furthermore, in a cross section perpendicular to the axis of rotation, the surface of the groove between the second point and the reference surface is defined as the second surface. The second surface is, for example, the surface SF2 described above. Furthermore, in a cross section perpendicular to the axis of rotation, the surfaces of the groove other than the first surface and the second surface are defined as the third surface.The third surface is, for example, the surface SF3 described above. Furthermore, in a cross section perpendicular to the axis of rotation, the third point is the point on the second surface that is furthest from the second point in the second direction. The third point is, for example, point P3 described above. Furthermore, in a cross section perpendicular to the axis of rotation, the fourth point is the point on the third surface that is furthest from the first point in the second direction. The fourth point is, for example, point P4 described above. Furthermore, in a cross section perpendicular to the axis of rotation, the fifth point is the intersection of the first line and the first circle, located radially outward from the first point. The fifth point is, for example, point P5 described above. Furthermore, in a cross section perpendicular to the axis of rotation, the sixth point is the intersection of a perpendicular line virtually drawn from the second point to the first line and the first line. The sixth point is, for example, point P6 described above. Furthermore, a line hypothetically drawn connecting the first point and the second point in a cross section perpendicular to the axis of rotation is defined as the second line. The second line is, for example, the line L2 described above. Furthermore, a line hypothetically drawn connecting the first point and the fourth point in a cross section perpendicular to the axis of rotation is defined as the third line. The third line is, for example, the line L3 described above. Furthermore, a line hypothetically drawn connecting the second point and the third point is defined as the fourth line. The fourth line is, for example, the line L4 described above. Furthermore, the angle formed by the first line and the second line in a cross section perpendicular to the axis of rotation is defined as the first angle. The first angle is, for example, the angle θ1 described above. Furthermore, the angle formed by the first line and the third line in a cross section perpendicular to the axis of rotation is defined as the second angle. The second angle is, for example, the angle θ2 described above. Furthermore, in a cross section perpendicular to the axis of rotation, the angle between the second line and the fourth line is defined as the third angle. The third angle is, for example, the angle θ3 described above. Also, in a cross section perpendicular to the axis of rotation, the distance between the first point and the sixth point is defined as the first distance. The first distance is, for example, the distance A described above. Also, in a cross section perpendicular to the axis of rotation, the distance between the fifth point and the sixth point is defined as the second distance. The second distance is, for example, the distance B described above.Furthermore, with respect to the first distance and the second distance, one of the following conditions <1-1> to <1-3> is met, with respect to the second angle, condition <2> is met, and with respect to the third angle, condition <3> is met. <1-1> If the first angle is greater than 0 degrees and less than 45 degrees, the first distance is greater than the second distance. <1-2> If the first angle is 45 degrees, the first distance and the second distance are equal. <1-3> If the first angle is greater than 45 degrees and less than 90 degrees, the first distance is less than the second distance. <2> The second angle is greater than 0 degrees and less than 90 degrees. <3> The third angle is 90 degrees or greater and less than the angle obtained by subtracting the first angle from 180 degrees.

[0162] As a result, the rotor, as it rotates, can draw surrounding fluid into the grooves on its outer surface, generating vortices within the grooves. Therefore, the rotor can cool itself by dissipating heat from the fluid flowing into the grooves. Thus, the rotor's cooling performance can be improved. Furthermore, by satisfying the above conditions, the groove shape can be optimized to suppress vortex separation within the grooves. Therefore, the rotor's cooling performance can be further improved.

[0163] Furthermore, in a second aspect of this embodiment, based on the first aspect described above, the rotor may include an iron core made of a soft magnetic material and permanent magnets embedded in the iron core. The iron core is, for example, the rotor iron core 311 described above. The permanent magnet is, for example, the permanent magnet 312 described above. The outer circumferential surface may be the outer circumferential surface of the iron core. The outer circumferential surface of the iron core is, for example, the outer circumferential surface 311A ​​of the rotor iron core 311 described above.

[0164] As a result, the rotor, as it rotates, draws surrounding fluid into grooves provided on the outer surface of the iron core, generating vortices within the grooves and thereby improving cooling performance.

[0165] Furthermore, in a third aspect of this embodiment, based on the second aspect described above, the groove may be provided radially outward from the permanent magnet.

[0166] This allows, for example, grooves to be placed in the circumferential position where the permanent magnet is embedded. As a result, the cooling of the permanent magnet can be promoted, and consequently, demagnetization due to heat can be suppressed.

[0167] Furthermore, in a fourth aspect of this embodiment, assuming the third aspect described above, when a second circle is hypothetically drawn in the cross-section with the rotation axis as the center and passing through the outermost radial endpoint of the permanent magnet, the difference between the radius of the first circle and the radius of the second circle may be greater than the sum of the first distance and the second distance, and less than twice the sum of the first distance and the second distance. The second circle is, for example, CC2 as described above. The radius of the first circle is, for example, radius R1 as described above. The radius of the second circle is, for example, radius R2 as described above.

[0168] This optimizes the cooling performance of the permanent magnets and suppresses demagnetization caused by heat.

[0169] Furthermore, in a fifth aspect of this embodiment, based on the first aspect described above, the rotor may comprise a cylindrical tube centered on the axis of rotation, permanent magnets arranged adjacent to the radially inner side of the tube, and an iron core made of a soft magnetic material, arranged adjacent to the radially inner side of the permanent magnets. The tube is, for example, the protective tube 313 described above. The permanent magnets are, for example, the permanent magnets 312 described above. The iron core is, for example, the rotor iron core 311. The outer circumferential surface is the outer circumferential surface of the tube, and the grooves may be provided in the tube. The outer circumferential surface of the tube is, for example, the outer circumferential surface 313A of the protective tube 313 described above.

[0170] As a result, the rotor, as it rotates, draws surrounding fluid into grooves provided on the outer surface of the tubes that hold the permanent magnets, generating vortices within the grooves and thereby improving cooling performance.

[0171] Furthermore, in the sixth aspect of this embodiment, assuming any one of the first to fifth aspects described above, the shape of the groove may differ between two cross-sections located at different positions in the axial direction.

[0172] This allows for the optimization of the groove shape according to the axial position, taking into account factors such as the surrounding fluid flow in the axial direction. As a result, the cooling performance of the rotor can be further improved.

[0173] Furthermore, in the seventh aspect of this embodiment, the rotor may rotate in the first direction, based on any one of the first to sixth aspects described above.

[0174] As a result, the rotor can generate vortices in the grooves that suppress separation as it rotates in the first direction, thereby appropriately improving the cooling performance of the rotor.

[0175] Furthermore, in the eighth aspect of this embodiment, a fluid may flow between the outer circumferential surface and the stator, based on any one of the first to seventh aspects described above.

[0176] This allows the rotor to be further cooled by the fluid flowing between the stator and the outer surface of the rotor.

[0177] Furthermore, in the ninth aspect of this embodiment, the rotating electric machine comprises a rotor described in any one of the first to eighth aspects described above, and the stator. The rotating electric machine is, for example, the rotating electric machine 300 described above.

[0178] This makes it possible to improve the cooling performance of the rotor mounted on a rotating electric machine.

[0179] Furthermore, in the tenth aspect of this embodiment, the refrigeration system includes the rotating electric machine described in the ninth aspect above. The refrigeration system is, for example, the refrigeration system 1 described above.

[0180] This makes it possible to improve the cooling performance of the rotor of a rotating electric machine mounted on a refrigeration system.

[0181] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims.

[0182] Finally, this application claims priority based on Japanese Patent Application No. 2024-169890, filed on 30 September 2024, and the entire contents of the Japanese Patent Application are incorporated herein by reference.

[0183] 1 Refrigeration unit 10 Compressor 20 Heat exchanger 30 Expansion mechanism 40 Heat exchanger 100 Casing 110 Impeller chamber 111 Diffuser 120 Intake pipe 130 Discharge pipe 140 Motor chamber 150 Outlet 200 Impeller 250 Rotating shaft 270 Hollow section 271 Opening 272 Opening 300 Rotating electric machine 310 Rotor 311 Rotor core 311A ​​Outer surface 311B Reference surface 311C Groove 312 Permanent magnet 313 Protective tube 313A Outer surface 313B Reference surface 313C Groove 320 Stator 321 Stator core 321A Back yoke section 321B Teeth section 322 Windings A, B Distance AX Rotation axis CC1, CC2 Circle L1~L4 Line P1~P6 Point R1, R2 Radius RD Rotation direction SF1~SF3 Surface θ1~θ3 Angle

Claims

1. A rotor that faces radially inward from a stator (320) and is rotatable about a rotation axis (AX), wherein the outer circumferential surfaces (311A, 313A) of the rotor have reference surfaces (311B, 313B) corresponding to a part of the circumferential surface of a cylinder centered on the rotation axis (AX), and grooves (311C, 313C) adjacent to the reference surfaces (311B, 313B), one direction in the circumferential direction with respect to the rotation axis (AX) is defined as a first direction (RD), the direction opposite to the first direction (RD) in the circumferential direction is defined as a second direction, and in a cross section perpendicular to the rotation axis (AX), a circle virtually drawn as a circle including the reference surfaces (311B, 313B) is defined as a first circle (CC1). In the grooves (311C, 313C), the position closest to the rotation axis (AX) in the radial direction with respect to the rotation axis (AX) is defined as the first point (P1), and in the grooves (311C, 313C), the position located radially outside the first point (P1) and radially inside the first circle (CC1), and furthest from the first point (P1) in the first direction is defined as the second point (P2), and a line drawn virtually as a straight line passing through the rotation axis (AX) and the first point (P1) is defined as the first line (L1), and the surface of the grooves (311C, 313C) between the first point (P1) and the second point (P2) is defined as the first surface (SF1). The surface of the groove (311C, 313C) between the second point (P2) and the reference surfaces (311B, 313B) is defined as the second surface (SF2), and the grooves (311C, 313C) other than the first surface (SF1) and the second surface (SF2) are defined as the second surface (SF2),Let the plane of 313C) be the third plane (SF3), and let the point on the second plane (SF2) that is furthest from the second point (P2) in the second direction be the third point (P3), and let the point on the third plane (SF3) that is furthest from the first point (P1) in the second direction be the fourth point (P4), and let the intersection point of the first line (L1) and the first circle (CC1) be the fifth point (P5), and let the intersection point of the first line (L1) and the first line (L1) be the sixth point (P6), and let the line drawn virtually as a straight line connecting the first point (P1) and the second point (P2) be the second line (L2), Let the line hypothetically drawn connecting the first point (P1) and the fourth point (P4) be the third line (L3), and let the line hypothetically drawn connecting the second point (P2) and the third point (P3) be the fourth line (L4), let the angle between the first line (L1) and the second line (L2) be the first angle (θ1), let the angle between the first line (L1) and the third line (L3) be the second angle (θ2), let the angle between the second line (L2) and the fourth line (L4) be the third angle (θ3), let the distance between the first point (P1) and the sixth point (P6) be the first distance (A), and let the distance between the fifth point (P5) and the sixth point (P6) be the second distance (B), A rotor in which, when the first angle (θ1) is greater than 0 degrees and less than 45 degrees, the first distance (A) is greater than the second distance (B); when the first angle (θ1) is 45 degrees, the first distance (A) and the second distance (B) are equal; when the first angle (θ1) is greater than 45 degrees and less than 90 degrees, the first distance (A) is less than the second distance (B); the second angle (θ2) is greater than 0 degrees and less than 90 degrees; and the third angle (θ3) is 90 degrees or greater and less than the angle obtained by subtracting the first angle from 180 degrees.

2. The rotor according to claim 1, comprising an iron core (311) formed of a soft magnetic material, and a permanent magnet (312) embedded in the iron core, wherein the outer surface is the outer surface (311A) of the iron core.

3. The rotor according to claim 2, wherein the groove (311C) is provided radially outward from the permanent magnet (312).

4. In the cross-section, when a second circle (CC2) is hypothetically drawn with the rotation axis (AX) as the center and passing through the outermost radial endpoint of the permanent magnet (312), the difference between the radius (R1) of the first circle (CC1) and the radius (R2) of the second circle (CC2) is greater than the sum of the first distance (A) and the second distance (B), and less than twice the sum of the first distance (A) and the second distance (B), the rotor according to claim 3.

5. The rotor according to claim 1, comprising: a cylindrical tube (313) centered on the rotation axis (AX); a permanent magnet (312) adjacent to the radially inner side of the tube (313); and an iron core (311) made of a soft magnetic material, adjacent to the radially inner side of the permanent magnet (312), wherein the outer surface is the outer surface (313A) of the tube, and the groove (313C) is provided in the tube (313).

6. The rotor according to any one of claims 1 to 5, wherein the shape of the grooves (311C, 313C) differs between two cross-sections located at different positions in the axial direction.

7. The rotor according to any one of claims 1 to 6, which rotates in the first direction (RD).

8. The rotor according to any one of claims 1 to 7, wherein a fluid flows between the outer circumferential surfaces (311A, 313A) and the stator (320).

9. A rotating electric machine comprising a rotor (310) according to any one of claims 1 to 8, and a stator (320).

10. A refrigeration apparatus comprising the rotating electric machine (300) described in claim 9.

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