Rotating electrical machine

Abstract

On the outer side surfaces (36, 37) of the faces of the stator core (32) of the rotating electric machine as the radial outer sides, grooves (36) extending in the axial direction are formed, and in the grooves (36), first protrusions (61) curved toward the radial outer sides and recesses (63) curved toward the radial inner sides are formed in cross sections orthogonal to the axial direction, and the shortest length between the peripheral wall surface of the slot (41) and the first protrusion (61) is shorter than the length between the peripheral wall surface of the slot (41) and the portion other than the first protrusion (61) in the groove (36).

Description

Technical Field

[0001] This disclosure relates to a rotary electric motor. Background Technology

[0002] In the rotary motor disclosed in Patent Document 1, a notch is formed on the radially outer surface of the stator core to serve as a flow path for the refrigerant. In this rotary motor, the thermal resistance is increased by shortening the distance between the notch and the root of the tooth, thereby reducing the heat transferred from the weld point to the tooth when the stator core and the housing are fixed by welding.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-278673 Summary of the Invention

[0006] -The technical problem the invention aims to solve-

[0007] However, in refrigeration systems operating in a refrigeration cycle, when the pressure inside the compressor is high during operation, a higher viscosity refrigeration oil is preferable. This is because it suppresses the flow of the refrigeration oil within the compressor, thereby ensuring the oil level in the oil reservoir.

[0008] Here, the refrigerant oil in the compressor is stored again in the oil reservoir through the notch. However, the higher the viscosity of the refrigerant oil, the greater the flow resistance when passing through the notch. Therefore, by increasing the flow area of ​​the notch (the cross-sectional area orthogonal to the extension direction of the notch), the flow resistance can be suppressed. However, if the flow area is increased, thin-walled sections will be created in the stator core. In such thin-walled sections, the magnetic circuit width becomes narrower, making magnetic saturation more likely. If magnetic saturation occurs, iron losses increase, potentially leading to a decrease in the efficiency of the rotating motor.

[0009] The purpose of this disclosure is to provide a rotary motor that suppresses the reduction of magnetic properties and suppresses the flow path resistance of the fluid through which it passes.

[0010] - Technical solutions used to solve technical problems -

[0011] In the first aspect of this disclosure, A rotary motor is arranged inside a housing 21 having a cylindrical body 22. The rotary motor includes a stator 31 and a rotor 40. The stator 31 is arranged inside the body 22 and has a stator core 32 and a coil 33. The stator core 32 has a cylindrical yoke 34 and a plurality of teeth 35 extending radially inward from the yoke 34 and arranged circumferentially along the yoke 34. The coil 33 is arranged in a slot 41 formed between two adjacent teeth 35 in the circumferential direction. The rotor 40 is arranged inside the stator core 32 and rotates around the rotation axis. On the outer surfaces 36 and 37 of the stator core 32, which are the radially outer surfaces, grooves 36 extending axially along the yoke 34 are formed. When viewed from a cross-section orthogonal to the stated axis, A first protrusion 61 that bends outward in the radial direction and a recess 63 that bends inward in the radial direction are formed in the groove 36. The shortest length between the peripheral wall of the groove 41 and the first protrusion 61 is shorter than the length between the portion of the groove 36 other than the first protrusion 61 and the peripheral wall of the groove 41.

[0012] In the first aspect, an axially extending flow path is formed between the groove 36 and the inner surface of the body 22. Here, for example, when high-viscosity refrigeration oil flows in this flow path, it is preferable to increase the hydraulic diameter of the flow path to suppress the flow resistance of the refrigeration oil. If the hydraulic diameter is increased, the cross-sectional area orthogonal to the extension direction of the flow path, i.e., the flow path area, increases, and the outer surfaces 36, 37 of the stator core 32 are correspondingly reduced. Therefore, a thinner section (i.e., a shorter section between the peripheral walls of the groove 36 and the slot 41) is generated in the stator core 32 when viewed from the cylinder axis direction. In such a thin-walled section, the width of the magnetic flux path becomes narrower, resulting in magnetic saturation. As a result, iron losses increase and the efficiency of the rotating motor decreases.

[0013] Therefore, in the first aspect, a first protrusion 61 is formed in the groove 36. The first protrusion 61 is formed to protrude radially outward from the groove 36 when viewed in a cross-section orthogonal to the axial direction. Therefore, it is possible to suppress the formation of a portion in the stator core 32 where the magnetic circuit width narrows. Since the recess 63 is formed to be recessed radially inward, it is possible to suppress the reduction of the flow path area. As a result, it is possible to suppress the reduction of the efficiency of the rotating motor and to suppress the flow path resistance of the fluid.

[0014] The second aspect is, based on the first aspect, When viewed from a cross-section orthogonal to the stated axis, A second protrusion 62 is formed in the groove 36, and the second protrusion 62 is connected to the portion other than the groove 36 in the outer surfaces 36, 37 and bends radially outward.

[0015] In the second aspect, by forming the second protrusion 62, the flow of magnetic flux becomes smoother. Compared to the case where the second protrusion 62 is not formed, the area that does not function as a magnetic circuit can be reduced, resulting in an increase in the flow path area and cost savings in material costs. In addition, in the case where the second protrusion 62 is not formed, the contact area between the radially outer surface of the stator core 32 and the inner surface of the body 22 is larger, thereby increasing pressure loss, while in the second aspect, the increase in pressure loss can be suppressed.

[0016] The third aspect is, based on the first or second aspect, When viewed from a cross-section orthogonal to the stated axis, The first protrusion 61 and the recess 63 are connected to each other by a smooth curve.

[0017] In the third aspect, by connecting the first protrusion 61 and the recess 63 with a smooth curve, the flow path resistance for the fluid flowing in the flow path can be suppressed.

[0018] The fourth aspect is, based on any one of the first to third aspects, When viewed from a cross-section orthogonal to the stated axis, Let D be the maximum radial length between the groove 36 and the inner surface of the body 22. When the length of the groove 36 in the direction orthogonal to the radial direction is set to W, It satisfies: 2.5×D≤W≤5.0×D.

[0019] In the fourth aspect, by forming the groove 36 such that the maximum radial length D between the groove 36 and the inner surface of the body 22 and the length W of the groove 36 in the radially orthogonal direction satisfy the above relationship, the same effect as in the first aspect can be obtained.

[0020] The fifth aspect is, based on any one of the first to fourth aspects, When viewed from a cross-section orthogonal to the stated axis, Let T be the length of the toothed portion 35 in the direction orthogonal to the radial direction. When the shortest length between the peripheral wall of the groove 41 and the outer surfaces 36 and 37 is defined as d1, It satisfies: T≤1.7×d1.

[0021] In the fifth aspect, by satisfying the above formula with the length T of the first protrusion 61 formed as the tooth 35 in the radially orthogonal direction and the shortest length d1 between the peripheral wall surface of the groove 41 and the outer surface 36, 37, the same effect as in the first aspect can be obtained.

[0022] The sixth aspect is, based on any one of the first to fifth aspects, The groove 36 is formed on the radial outer side of the tooth 35 in the outer surfaces 36, 37.

[0023] In the sixth aspect, when the stator core 32 is viewed axially, the region where the teeth 35 are formed is radially longer than the portion where the teeth 35 are not formed (i.e., the portion with only the yoke 34). By providing the groove 36 at such a location, the same effect as in the first aspect can be obtained.

[0024] The seventh aspect is a compressor comprising a rotary motor as described in any one of the first to sixth aspects and a compression mechanism 50 driven by the rotary motor.

[0025] In the seventh aspect, it is possible to suppress the flow resistance of the refrigeration oil stored in the compressor 20 and to suppress the reduction in the efficiency of the compressor 20.

[0026] The eighth aspect of this disclosure is a refrigeration device comprising a rotary motor as described in any one of the first to sixth aspects.

[0027] In the eighth aspect, it is possible to suppress the decrease in efficiency of the rotating motor and the decrease in efficiency of the refrigeration device. Attached Figure Description

[0028] Figure 1 This is a piping configuration diagram of the refrigerant circuit included in the refrigeration device of this embodiment.

[0029] Figure 2 This is a schematic diagram showing a cross-section along the axial direction of the compressor.

[0030] Figure 3 This is a schematic diagram showing a cross-section orthogonal to the compressor's axis.

[0031] Figure 4 It is Figure 3 A magnified portion of the image.

[0032] Figure 5 It is a graph showing the relationship between the ratio of the length of the tooth in the radially orthogonal direction to the length of the shortest magnetic path width and the efficiency of the rotating motor.

[0033] Figure 6It is a graph showing the relationship between the ratio and the flow path area, which is the ratio of the length of the trench in the direction orthogonal to the radial direction to the length in the radial direction.

[0034] Figure 7 It is a graph showing the relationship between the ratio and the length of the shortest magnetic path width, which is the ratio of the length of the trench in the direction orthogonal to the radial direction to the length in the radial direction.

[0035] Figure 8 It is a graph showing the relationship between the ratio and the hydraulic diameter of the oil flow path, which is the ratio of the length of the groove in the direction orthogonal to the radial direction to the length in the radial direction.

[0036] Figure 9 The stator core involved in the modified example is equivalent to Figure 3 A schematic cross-sectional view.

[0037] Figure 10 The stator core involved in the modified example is equivalent to Figure 3 A schematic cross-sectional view.

[0038] Figure 11 The stator core involved in the modified example is equivalent to Figure 3 A schematic cross-sectional view.

[0039] Figure 12 The stator core involved in the modified example is equivalent to Figure 3 A schematic cross-sectional view. Detailed Implementation

[0040] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that this disclosure is not limited to the embodiments shown below, and various modifications can be made without departing from the technical concept of this disclosure. The accompanying drawings are for conceptual illustration of this disclosure; therefore, for ease of understanding, dimensions, scales, or quantities may sometimes be exaggerated or simplified as needed.

[0041] (1) Overview of the refrigeration unit

[0042] The rotary motor 30 disclosed herein is applied to a refrigeration unit 1. For example... Figure 1 As shown, the refrigeration unit 1 has a refrigerant circuit 1a filled with refrigerant. The refrigerant circuit 1a includes a compressor 20, a radiator 2, a pressure reducing mechanism 3, and an evaporator 4. The pressure reducing mechanism 3 is an expansion valve. The refrigerant circuit 1a operates on a vapor compression refrigeration cycle.

[0043] In the refrigeration cycle, the refrigerant compressed by the compressor 20 dissipates heat to the air in the radiator 2. The dissipated refrigerant is then depressurized by the pressure reducing mechanism 3 and evaporates in the evaporator 4. The evaporated refrigerant is then drawn into the compressor 20.

[0044] Refrigeration unit 1 is an air conditioning unit. The air conditioning unit can also be a dedicated refrigeration unit, a dedicated heating unit, or an air conditioning unit that switches between refrigeration and heating. In this case, the air conditioning unit has a switching mechanism (e.g., a four-way reversing valve) to switch the refrigerant circulation direction. Refrigeration unit 1 can also be a water heater, a cooling unit, or a cooling device for cooling the air inside a storage facility. The cooling device cools the air inside cold storage rooms, freezers, containers, etc. The expansion mechanism consists of an electronic expansion valve, a temperature-sensing expansion valve, an expander, or a capillary tube.

[0045] (2) Compressor

[0046] like Figure 2 As shown, compressor 20 is a rotary fluid machine. Compressor 20 has a housing 21, an electric motor 30, a drive shaft 28, and a compression mechanism 50.

[0047] (2-1) Casing

[0048] The housing 21 houses the electric motor 30, drive shaft 28, and compression mechanism 50. The housing 21 is a fully enclosed container. The interior of the housing 21 is filled with high-pressure refrigerant ejected from the compression mechanism 50.

[0049] The housing 21 is made of metal. The housing 21 has a body 22, a bottom 23, and a top 24. The body 22 is a cylindrical metal component. The body 22 has a cylindrical inner surface on its radially inward side. Openings are formed at both ends of the body 22 along its cylindrical axis. In this embodiment, the cylindrical axis of the body 22 is aligned with the vertical direction. The bottom 23 closes the opening on the lower side of the body 22. The top 24 closes the opening on the upper side of the body 22.

[0050] (2-2) Electric motor

[0051] like Figure 2 As shown, the electric motor 30 is positioned above the compression mechanism 50. Figure 3 As shown, the electric motor 30 has a stator 31 and a rotor 40. The electric motor 30 is an example of the rotating electric motor 30 of this disclosure.

[0052] The stator 31 is located inside the body 22. The stator 31 has a stator core 32 and a coil 33.

[0053] The stator core 32 has a cylindrical yoke 34 and a plurality of teeth 35 (nine in this example) extending radially inward from the yoke 34 and arranged circumferentially along the yoke 34. The stator core 32 is constructed by stacking electromagnet steel plates along the cylindrical axis of the yoke 34.

[0054] It should be noted that the stator core 32 can also be made of soft magnetic materials other than electromagnetic steel plates. For example, the stator core 32 can also be made of materials including amorphous alloys, nanocrystalline materials, and powder cores. It should also be noted that the stator core 32 can be either a single-piece core or a segmented core. A single-piece core refers to a core that is not segmented in the direction perpendicular to the axial direction. A segmented core refers to a core that is segmented in the direction perpendicular to the axial direction.

[0055] The coil 33 is wound on the tooth 35. The coil 33 is arranged in a groove 41 formed between two adjacent teeth 35 in the circumferential direction of the yoke 34. The groove 41 is formed to extend axially. In this embodiment, a plurality of grooves 41 are formed (nine in this embodiment).

[0056] The rotor 40 is arranged inside the stator core 32. The rotor 40 rotates around its rotation axis. The rotor 40 is fixed to a drive shaft 28, which is configured to rotate freely around its rotation axis. In other words, the rotor 40 is configured to rotate freely around its rotation axis. The rotor 40 is cylindrical. A plurality of (six in this example) through holes 42 are formed in the rotor core of the rotor 40. Permanent magnets are arranged in the through holes 42. In this embodiment, the direction of the rotation axis of the rotor 40 is aligned with the vertical direction. In a cross-section orthogonal to the axial direction of the yoke 34, the rotation axis of the rotor 40 coincides with the center of the stator core 32.

[0057] In the following description, the direction of the cylinder axis of the yoke 34 is sometimes referred to as the "axial direction". The direction orthogonal to the cylinder axis of the yoke 34 is sometimes referred to as the "radial direction". In the direction orthogonal to the cylinder axis of the yoke 34, the direction from the center of the stator core 32 toward the body 22 is sometimes referred to as the "radial outer direction", and the direction from the body 22 toward the center of the stator core 32 is sometimes referred to as the "radial inner direction". The direction around the cylinder axis of the yoke 34 is sometimes referred to as the "circumferential direction".

[0058] The operating frequency of the electric motor 30 is controlled by a frequency converter. In other words, the compressor 20 is a variable frequency compressor with a variable operating frequency.

[0059] (2-3) Drive shaft

[0060] The drive shaft 28 extends vertically along the cylindrical axis of the housing 21. The drive shaft 28 is driven to rotate by the electric motor 30. The drive shaft 28 is supported by the bearing 29 to enable rotation.

[0061] (2-4) Compression mechanism

[0062] The compression mechanism 50 includes a rotary fluid mechanism. The compression mechanism 50 has a cylinder 51 and a piston 52 disposed inside the cylinder 51. A cylinder chamber 53 is formed between the inner circumferential surface of the cylinder 51 and the outer circumferential surface of the piston 52. In the cylinder chamber 53, fluid is compressed by the piston 52, which is driven by a drive shaft 28.

[0063] (2-5) Inhalation pipe and ejection pipe

[0064] The compressor 20 has a suction pipe 45 and a discharge pipe 46. The suction pipe 45 extends radially through the body 22 and communicates with the cylinder chamber 53. Low-pressure refrigerant from the refrigerant circuit 1a is drawn into the cylinder chamber 53 via the suction pipe 45. The discharge pipe 46 extends axially through the top 24 and communicates with the internal space of the housing 21. The refrigerant compressed by the compression mechanism 50 flows through the oil flow path S1 of the motor 30, and then is sent to the refrigerant circuit 1a from the discharge pipe 46.

[0065] (3) The issue of the oil flow path formed between the groove on the outer surface of the stator core and the inner surface of the body.

[0066] At the lower part of the housing 21, an oil reservoir R for storing refrigeration oil is formed (see reference). Figure 2 The refrigerant oil in the oil reservoir R is drawn up by a pump located at the lower end of the drive shaft 28 and supplied to the sliding portion of the compressor mechanism 50. Through the operation of the compressor 20, the refrigerant oil in the oil reservoir, along with the refrigerant sprayed from the compressor mechanism 50, moves to above the motor 30 inside the housing 21, and then is stored again in the oil reservoir R through the oil flow path S1 formed between the groove 36 and the inner surface of the body 22. In other words, refrigerant and refrigerant oil are sealed in the refrigerant circuit 1a of this disclosure.

[0067] Here, when the refrigerant sealed in the refrigerant circuit 1a is carbon dioxide refrigerant, which is a natural refrigerant, its pressure needs to be higher than that of other refrigerants (such as R32, which is an HFC refrigerant). In this case, if the viscosity of the refrigeration oil in the compressor is low, the fluidity of the refrigeration oil becomes high, and the refrigeration oil becomes difficult to return to the oil reservoir R.

[0068] Therefore, although using a higher viscosity refrigeration oil can suppress the flow of the refrigeration oil, it is necessary to suppress the flow resistance (pipeline resistance) of the oil flow path S1. This is because if the flow resistance of the oil flow path S1 is high, the higher viscosity refrigeration oil becomes difficult to return to the oil reservoir R.

[0069] The following conclusion has been reached: the higher the hydraulic diameter of the oil flow path S1, the lower the flow resistance. The hydraulic diameter is related to the size of the flow path cross-sectional area of ​​the oil flow path S1. Specifically, the hydraulic diameter is represented by (hydraulic diameter) = 4 × (flow path cross-sectional area) / (wetted perimeter). The wetted perimeter is the circumference of the inner circumferential surface (wall) in the flow path cross-section. Thus, with the wetted perimeter constant, a larger hydraulic diameter results in a larger flow path cross-sectional area of ​​the oil flow path S1. Therefore, with the wetted perimeter constant, increasing the flow path cross-sectional area of ​​the oil flow path S1 can reduce the flow resistance.

[0070] However, if the cross-sectional area of ​​the oil flow path S1 is increased, a thinner section will appear in the stator core 32. That is, when viewed axially, a shorter section will appear between the outer surfaces 36 and 37 of the stator core 32 and the peripheral wall of the slot 41. In such a section, the width through which the magnetic flux passes narrows, making magnetic saturation more likely and increasing iron losses. If iron losses increase, the efficiency of the motor (the efficiency of a rotating motor) will decrease. With this problem in mind, in this embodiment, the stator core 32 is configured to suppress the flow resistance of the oil flow path S1 and suppress the increase of iron losses.

[0071] (4) Detailed information about the stator core

[0072] The following is for reference Figure 4 The structure of the stator core 32 will be explained. It should be noted that, unless otherwise specified, the following descriptions refer to cross-sections orthogonal to the axial direction when viewed from the front (viewed from the front side of the paper). Figure 4 The shape of the stator core 32 is described.

[0073] The outer surfaces 36 and 37 of the stator core 32 (in other words, the outer periphery of the stator core 32) have a plurality of fixed surfaces 37 and a plurality of grooves 36 alternately connected along the circumference of the stator core 32. The inner surface of the stator core 32 (in other words, the inner periphery of the stator core 32) includes the peripheral wall surface of the groove 41 and the radially inner surface of the tooth 35. The peripheral wall surface of the groove 41 is the surface that constitutes the peripheral wall of the groove 41. Specifically, the peripheral wall surface of the groove 41 includes the mutually facing surfaces of two circumferentially adjacent teeth 35 and the radially inner surface of the yoke 34 sandwiched by the two teeth 35.

[0074] (4-1) Fixed surface

[0075] The fixing surface 37 is the outer surface of the stator core 32 fixed within the body 22. In other words, the fixing surface 37 is the surface that contacts the inner surface of the body 22. It should be noted that the fixing surface 37 may not directly contact the inner surface of the body 22, or a predetermined clamping component (not shown) may be provided between the inner surface of the body 22 and the fixing surface 37. The clamping component may be, for example, a resin component or a ceramic component. The fixing surface 37 may also be welded to the body 22. When the fixing surface 37 is welded to the body 22, there may be a gap between the fixing surface 37 and the inner surface of the body 22 that is not a flow path for oil. A gap that is not a flow path for oil means a gap whose hydraulic diameter is sufficiently small compared to the hydraulic diameter of the flow path S1 formed between the groove 36 and the inner surface of the body 22. For example, a gap that is not a flow path for oil means a gap whose hydraulic diameter is less than 1 / 100 of the hydraulic diameter of the flow path S1 formed between the groove 36 and the inner surface of the body 22.

[0076] (4-2) Trench

[0077] The groove 36 is an outer surface of the stator core 32 that is recessed radially inward, thereby forming an oil flow path S1 for refrigeration oil to pass through between the inner surface of the body 22 and the outer surface of the stator core 32. In a cross-section orthogonal to the axial direction, the groove 36 is located radially outward of the teeth 35 of the outer surfaces 36 and 37 of the stator core 32. In other words, the groove 36 and the teeth 35 are adjacent to each other radially.

[0078] In this embodiment, the groove 36 is not covered by a specified component but is exposed in the oil flow path S1. In other words, in this embodiment, the groove 36 is the outer surface of the stator 31. It should be noted that the groove 36 is preferably exposed without being covered by a specified component. When the groove 36 is covered by a specified component, it is preferable that the area of ​​the component is sufficiently smaller than the area of ​​the oil flow path S1 when viewed from the axial direction. For example, when the groove 36 is covered by a specified component, it is preferable that the area of ​​the component is less than 10% of the area of ​​the oil flow path S1 when viewed from the axial direction. The specified component is, for example, a varnish or resin component. It should be noted that, from the viewpoint of increasing the hydraulic diameter of the oil flow path S1, the groove 36 preferably does not contain a curve that bends radially outward, and preferably only contains a curve that bends radially inward.

[0079] The length of the groove 36 in the radially orthogonal direction is longer than the length of the tooth 35 in the radially orthogonal direction. Specifically, let the length of the groove 36 in the radially orthogonal direction be defined as length W. Let the length of the tooth 35 in the radially orthogonal direction be defined as length T. Length W is longer than length T. When a straight line, virtually drawn, passing through the rotation axis of the rotor 40 and the circumferential midpoint of the tooth 35 is defined as the first radial line, the groove 36 and the tooth 35 are formed in a line-symmetrical manner with respect to the first radial line. In other words, length W is the length of the groove 36 in the direction orthogonal to the first radial line, and length T is the length of the tooth 35 in the direction orthogonal to the first radial line.

[0080] The groove 36 has a first protrusion 61, a second protrusion 62, and a recess 63. In this embodiment, the second protrusion 62, the recess 63, the first protrusion 61, the recess 63, and the second protrusion 62 are formed from one end of the groove 36 in the circumferential direction to the other end. The first protrusion 61, the second protrusion 62, and the recess 63 are formed at both ends of the stator core 32 in the axial direction.

[0081] (4-2-1) First convex part

[0082] The first protrusion 61 curves radially outward. In other words, the first protrusion 61 is formed to bulge radially outward when viewed axially. In other words, the first protrusion 61 is formed to bulge from the stator core 32 toward the body 22 when viewed axially. In other words, the first protrusion 61 is formed to bulge from the groove 41 toward the oil flow path S1 when viewed axially. In yet another way, the first protrusion 61 is formed such that a portion of the groove 36 bulges smoothly radially outward when viewed axially. It should be noted that a portion of the first protrusion 61 may also contain minute straight lines or planes formed due to manufacturing reasons of the stator core 32. That is, the first protrusion 61 may not be strictly composed only of curved portions in a cross-section orthogonal to the axial direction.

[0083] When viewed from the front in a cross-section orthogonal to the axial direction, the predetermined position of the groove 36 is designated as P, and the predetermined position of the peripheral wall of the groove 41 is designated as Q. The first protrusion 61 is formed at the position where the length between P and Q is shortest. The shortest part between P and Q is the thinnest part of the wall thickness of the yoke 34. In this thin-walled part, the magnetic path width for magnetic flux flow is the narrowest. The first protrusion 61 is formed in the groove 36 at such a narrowing magnetic path width of the yoke 34.

[0084] Q is located at the connection between the tooth 35 and the yoke 34 on the peripheral wall of the groove 41. In other words, Q is located at the root of the yoke 34 of the tooth 35. P is located at the position where the length between P and Q is the shortest from the position of Q. In this embodiment, there are two portions with the shortest length between P and Q in a groove 36. That is, each groove 36 forms two first protrusions 61.

[0085] In other words, for a groove 36, the teeth 35 located radially inward on the groove 36 constitute the peripheral walls of two circumferentially adjacent grooves 41. Of the two first protrusions 61 formed in the groove 36, one first protrusion 61 includes a position P with the shortest length relative to a position Q of the peripheral wall of one of the two grooves 41, and the other first protrusion 61 includes a position P with the shortest length relative to a position Q of the peripheral wall of the other groove 41. In other words, in a groove 36, there is one location with the shortest length between P and Q relative to the peripheral wall of one of the two circumferentially adjacent grooves 41, and one location with the shortest length between P and Q relative to the peripheral wall of the other groove 41.

[0086] Two first protrusions 61 formed in a groove 36 are arranged symmetrically with respect to a first radial line. It should be noted that the shortest length between the first protrusion 61 and the peripheral wall of the groove 41 is only shorter than the length between the portion of the groove 36 excluding the first protrusion 61 and the peripheral wall of the groove 41. For example, the shortest length between the first protrusion 61 and the peripheral wall of the groove 41 can be a defined range of the first protrusion 61, a single point of the first protrusion 61, or more than two points of the first protrusion 61. The defined range can be a part or the entirety of the first protrusion 61. For example, when the shape of the root of the yoke 34 of the tooth 35 and the shape of the first protrusion 61 are both arcs with the same center, the shortest length between the first protrusion 61 and the peripheral wall of the groove 41 is within the defined range of the first protrusion 61.

[0087] When the top of the first protrusion 61 is set as P', the larger the length between P' and Q, the better the narrowing of the magnetic circuit width can be suppressed. However, correspondingly, the flow path cross-sectional area of ​​the oil flow path S1 becomes smaller, thus increasing the flow path resistance. Therefore, in the motor 30 of this embodiment, the length d1 between the first protrusion 61 and the peripheral wall of the groove 41 is configured to be shorter than the length d2 between the portion of the groove 36 other than the first protrusion 61 and the peripheral wall of the groove 41.

[0088] In other words, length d1 is the shortest length between the peripheral walls of groove 36 and groove 41. Here, as... Figure 5As shown, an investigation into the relationship between the efficiency of the rotary motor and the ratio of T to d1 (T / d1) reveals that the efficiency of the rotary motor decreases as T / d1 increases, and drops sharply from around 1.7. Therefore, it can be concluded that the efficiency of the rotary motor is good when T / d1 is below 1.7. Thus, the first protrusion 61 in this embodiment is formed to satisfy: T ≤ 1.7 × d1.

[0089] (4-2-2) Second convex part

[0090] like Figure 4 As shown, the second protrusion 62 is smoothly connected to the fixed surface 37 in a cross-section orthogonal to the axial direction and curves radially outward. In this embodiment, the second protrusion 62 is formed at both ends of each groove 36. That is, in this embodiment, each groove 36 has two second protrusions 62.

[0091] The second protrusion 62 curves radially outward. In other words, the second protrusion 62 is formed to bulge radially outward from the radially inward side when viewed axially. In other words, the second protrusion 62 is formed to bulge from the stator core 32 toward the body 22 when viewed axially. In yet another way, the second protrusion 62 is formed such that, when viewed from the front in a cross-section orthogonal to the axial direction, the circumferential end of the groove 36 smoothly bulges radially outward. It should be noted that a portion of the second protrusion 62 may also contain minute straight lines or planes formed due to manufacturing reasons of the stator core 32. That is, the second protrusion 62, in a cross-section orthogonal to the axial direction, may not be strictly composed only of curved portions.

[0092] (4-2-3) Concave part

[0093] The recess 63 bends radially inward in a cross-section orthogonal to the axial direction. In other words, when viewed from the axial direction, the recess 63 is formed to bulge from the radially outer side toward the radially inner side. In other words, the recess 63 is formed to bulge from the body 22 toward the stator core 32.

[0094] A recess 63 is formed between two first protrusions 61. A recess 63 is formed between adjacent first protrusions 61 and second protrusions 62. Specifically, the recess 63 is formed to connect two adjacent first protrusions 61. A recess 63 is formed to connect adjacent first protrusions 61 and second protrusions 62.

[0095] In this embodiment, three recesses 63 are formed in a groove 36. One recess 63 is connected to the first protrusion 61 by a smooth curve. Two recesses 63 are connected to the first protrusion 61 by a smooth curve, and are also connected to the second protrusion 62 by a smooth curve.

[0096] In other words, the recess 63 is connected to the adjacent circumferential surfaces by curves without bends or sharp points. It should be noted that "smooth" means "without bends or sharp points." In other words, the recess 63 is connected to the adjacent circumferential surfaces by curves without bends or sharp points.

[0097] In this embodiment, the three recesses 63 are respectively formed as elliptical arcs with the same major axis, minor axis, and center. The three recesses 63 are formed as elliptical arcs with their minor axes coinciding with the first radial line and their centers located on the first radial line.

[0098] It should be noted that a portion of the recess 63 may also contain minute straight lines or planes formed due to manufacturing reasons of the stator core 32. That is to say, the recess 63 may not be strictly composed of only curved sections in a cross-section orthogonal to the axial direction.

[0099] (5) The relationship between the length of the groove in the direction orthogonal to the radial direction and the radial length.

[0100] In this embodiment, the groove 36 is formed based on the relationship between the length W in the direction orthogonal to the radial direction and the radial length D.

[0101] In a cross-section orthogonal to the axial direction, the radial length D of the groove 36 is the maximum radial length between the groove 36 and the inner surface of the body 22. In other words, length D is equivalent to the radial length between the line virtually drawn by extending the fixed surface 37 of the stator core 32 and the deepest part of the groove 36. Furthermore, in a cross-section orthogonal to the axial direction, length D is equivalent to the radial length between the line virtually drawn by drawing the circumcircle of the stator core 32 and the deepest part of the groove 36. The deepest part of the groove 36 represents the position closest to the radial inner side of the groove 36.

[0102] In this embodiment, the deepest part of the groove 36 coincides with the first radial line. Therefore, in a cross-section orthogonal to the axial direction, the length D is equivalent to the length between the point where the line virtually drawn from the circumcircle of the stator core 32 intersects the first radial line and the point where the groove 36 intersects the first radial line.

[0103] In this embodiment, assuming that the flow path cross-section of the oil flow path S1 is approximately elliptical, the optimal ratio (W / D) of length W to length D in the direction orthogonal to the radial direction is determined. The optimal ratio is derived from the viewpoints of the flow path area of ​​the oil flow path S1, the shortest magnetic path width, and the hydraulic diameter of the oil flow path S1.

[0104] like Figure 6 As shown, the flow path area increases with the increase of the W / D value. Figure 7As shown, the shortest magnetic path width decreases with increasing W / D value, reaching a near-constant value when W / D is above 5. Furthermore, as... Figure 8 As shown, the hydraulic diameter increases with increasing W / D value, and the W / D value begins to decrease from around 5. Therefore, a W / D value was selected that yields good results for the flow path area, the shortest magnetic path width, and the hydraulic diameter of the oil flow path S1.

[0105] Specifically, the value of W / D is preferably 2.5 ≤ W / D ≤ 5.0, more preferably 2.7 ≤ W / D ≤ 4.75, and even more preferably 3.0 ≤ W / D ≤ 4.5. In other words, the circumferential length W is preferably 2.5 × D ≤ W ≤ 5.0 × D, more preferably 2.7 × D ≤ W ≤ 4.75 × D, and even more preferably 3.0 × D ≤ W ≤ 4.5 × D.

[0106] (6) Characteristics

[0107] (6-1) Feature 1

[0108] In this embodiment, a first protrusion 61 that bends radially outward and a recess 63 that bends radially inward are formed in the groove 36 of the stator core 32. When viewed in a cross-section orthogonal to the axial direction, the shortest length between the peripheral wall of the groove 41 and the first protrusion 61 is shorter than the length between the portion of the groove 36 other than the first protrusion 61 and the peripheral wall of the groove 41.

[0109] According to this embodiment, a first protrusion 61 is formed in the groove 36 constituting the oil flow path S1 in the portion where the stator core 32 has a thinner wall thickness. Therefore, even if the flow path area of ​​the oil flow path S1 is increased, the narrowing of the magnetic circuit width in the thinner wall portion can be suppressed. As a result, the increase in iron loss can be suppressed, and the decrease in the efficiency of the rotating motor can be suppressed.

[0110] In addition, since the recess 63 is formed radially inward, the reduction of the flow path area can be suppressed. Thus, the flow path resistance of the oil flow path S1 can be suppressed while simultaneously suppressing the reduction in the efficiency of the rotary motor. It should be noted that, when comparing the flow path area of ​​the prior art (without the first protrusion 61) with that of this embodiment, while fixing the length of the shortest magnetic path width and the hydraulic diameter, the following conclusion is drawn: this embodiment is 1.5 times larger than the prior art.

[0111] (6-2) Feature 2

[0112] In this embodiment, when viewed in a cross-section orthogonal to the axial direction, a second protrusion 62 is formed in the groove 36, which is connected to the portion other than the groove 36 in the outer surfaces 36 and 37 and bends radially outward.

[0113] By forming the second protrusion 62, the flow of magnetic flux becomes smoother. Compared to the case where the second protrusion 62 is not formed, the area that does not function as a magnetic circuit can be reduced, resulting in an increase in the flow area of ​​the oil flow path S1. In addition, when the second protrusion 62 is not formed in the groove 36, the fixing surface 37 of the stator core 32 is increased, and the area of ​​contact between the radially outer surface of the stator core 32 and the inner surface of the body 22 is increased, thereby increasing the pressure loss. However, in the motor 30 of this embodiment, the increase in pressure loss can be suppressed.

[0114] (6-3) Feature 3

[0115] In this embodiment, when viewed in a cross-section orthogonal to the axial direction, the first protrusion 61 and the recess 63 are connected to each other by a smooth curve.

[0116] By connecting the first protrusion 61 and the recess 63 with a smooth curve, the flow resistance relative to the flow area of ​​the oil flow path S1 can be suppressed. Therefore, even refrigeration oil with relatively high viscosity can flow easily in the oil flow path S1.

[0117] (6-4) Feature 4

[0118] In this embodiment, when the maximum radial length between the groove 36 and the inner surface of the body 22 is set as D, and the length of the groove 36 in the direction orthogonal to the radial direction is set as W, It satisfies: 2.5×D≤W≤5.0×D.

[0119] In this way, by forming the groove 36 such that the length W of the groove 36 in the direction orthogonal to the radial direction satisfies the above-mentioned numerical range, it is possible to suppress the increase of iron loss and suppress the decrease of the efficiency of the rotating motor.

[0120] (6-5) Feature 5

[0121] In this embodiment, when viewed in a cross-section orthogonal to the axial direction, the length of the tooth 35 in the radial direction is defined as T, and the shortest length between the peripheral wall of the groove 41 and the outer surfaces 36 and 37 is defined as d1. Satisfies: T≤1.7×d1.

[0122] By forming the groove 36 such that the shortest length d1 between the peripheral wall of the groove 41 and the outer surfaces 36 and 37 satisfies the above-mentioned numerical range, it is possible to suppress the increase of iron loss and suppress the decrease of the efficiency of the rotating motor.

[0123] (6-6) Feature 6

[0124] In this embodiment, the groove 36 is formed radially outward of the teeth 35 in the outer surfaces 36 and 37. When viewed axially, the region in the stator core 32 where the teeth 35 are formed has the longest radial length. By providing the groove 36 at this location, the increase in iron loss can be suppressed, and the decrease in the efficiency of the rotating motor can be suppressed.

[0125] (7) Variations

[0126] The above-described embodiments can also adopt the structure described below.

[0127] like Figures 9-11 As shown, when viewed axially, the recess 63 formed in the groove 36 can be formed simply by bending radially inward, or it can be formed by bending in a circular arc or an elliptical arc. Specifically, as Figure 9 As shown, the groove 36 can also be formed with three recesses 63 each coinciding with the circumference of a circle (double-dotted line). In this case, the center of the circle (double-dotted line) that contacts the three recesses 63 is located on the first radial line. Figure 10 As shown, it can also be formed such that the three recesses 63 each coincide with the circumference of an ellipse (double-dotted line). In this case, the minor axis of the ellipse (double-dotted line) tangent to the three recesses 63 coincides with the first radial line. Figure 11 In this groove 36, the recess 63 is formed only between the first protrusion 61 and the second protrusion 62. The groove 36 may also be formed such that the recess 63 coincides with the circumference of a circle (dashed line).

[0128] like Figure 12 As shown, the stator core 32 can also be formed such that the slot 41 is closed radially inward when viewed from the axial direction. In other words, the stator core 32 can also be formed such that the inner surface of the stator core 32 includes the radially inward surface of the tooth 35, but does not include the peripheral wall surface of the slot 41.

[0129] A rotary electric motor can also be used in an expander (illustration omitted). For example, the expander is the pressure reducing mechanism 3 of the refrigeration unit 1. The expander includes an expansion mechanism and a generator. The generator is equivalent to the rotary electric motor of this disclosure. The expansion mechanism includes, for example, a rotary fluid machine. The generator is arranged above the expansion mechanism in the vertical direction.

[0130] The groove 36 may also not have the second protrusion 62. That is, the two ends of the groove 36 in the circumferential direction may not be formed to bend radially outward.

[0131] Viewed axially, the entire groove 36 can be composed of curves, or a portion of the groove 36 can contain straight lines. In other words, the groove 36 can be composed of both curves and straight lines, or it can be composed of only curves without straight lines. For example, straight lines can be formed between the two ends of the groove 36 in the circumferential direction and the first protrusion 61, and straight lines can also be formed between the first protrusion 61 and the recess 63.

[0132] When viewed from the axial direction, the entire groove 36 can be composed of smooth curves and straight lines, or it can be composed of only smooth curves. In other words, the groove 36 can also be configured to not contain any bends or sharp points.

[0133] When viewed from the axial direction, the groove 36 can be composed of both uneven curves and straight lines, or it can be composed of only uneven curves. In other words, the groove 36 can also be configured to include bends or sharp points.

[0134] The groove 36 may also be configured such that, apart from the first protrusion 61, it does not include a curve that bends radially outward.

[0135] The groove 36 may also be configured such that, apart from the first protrusion 61 and the second protrusion 62, it does not include a curve that bends radially outward.

[0136] The groove 36 may also be configured to include only a curve that bends radially inward, except for the first protrusion 61.

[0137] The groove 36 may also be configured to include only a curve that bends radially inward, except for the first protrusion 61 and the second protrusion 62.

[0138] The recess 63 of the stator core 32 can also be configured to be formed only between the two first protrusions 61, and not between adjacent first protrusions 61 and second protrusions 62.

[0139] The recess 63 of the stator core 32 can also be configured to be formed only between adjacent first protrusions 61 and second protrusions 62, and not between two first protrusions 61.

[0140] The first protrusion 61 and the concave portion 63 of the stator core 32 may not be connected to each other by a smooth curve.

[0141] The length W of the groove 36 in the radially orthogonal direction can also be set independently of the value of the radial length D.

[0142] The shortest length d1 between the peripheral wall of the slot 41 and the outer surface of the stator core 32 can be set independently of the length T of the tooth 35 in the radially orthogonal direction. In the two first protrusions 61 formed in a groove 36, the shortest length d1 between one first protrusion 61 and the peripheral wall of the slot 41 and the shortest length d1 between the other first protrusion 61 and the peripheral wall of the slot 41 can be the same or different.

[0143] The number of grooves 36 in the stator core 32 can be the same as or less than the number of teeth 35. In other words, the grooves 36 can be formed on the radial outer side of all teeth 35, or they can be formed on the radial outer side of more than one tooth 35, while the radial outer side of the other teeth 35 does not have grooves 36.

[0144] In the above description, the case of an embedded magnet synchronous rotor with permanent magnets arranged on rotor 40 was used as an example, but it is not limited to this. For example, it could also be a surface magnet synchronous rotor with permanent magnets arranged on the radially outer side, a reluctance rotor with inductance varying according to rotor position, or a squirrel-cage induction rotor in which multiple conductor rods extending axially are connected by end rings and embedded in an iron core. Furthermore, the case of nine teeth 35 was used as an example, but it could also be ten or more, or eight or fewer but two or more. The case of a rotary fluid machine with compression and expansion mechanisms was used as an example, but it is not limited to this. The compression and expansion mechanisms could also be vortex fluid machines, screw fluid machines, or centrifugal fluid machines.

[0145] The embodiments and variations have been described above. However, it should be understood that various changes can be made to the embodiments and details without departing from the spirit and scope of the claims. The embodiments and variations described above can be appropriately combined or substituted as long as the function of the object of this disclosure is not affected. The terms "first," "second," etc., used above are used to distinguish statements containing these terms and are not intended to limit the number or order of the statements.

[0146] -Industry Applicability-

[0147] In summary, this disclosure is useful for rotating electric machines, compressors, and refrigeration devices.

[0148] - Symbol Explanation -

[0149] 1. Refrigeration unit

[0150] 20 Compressors

[0151] 21. Chassis

[0152] 22. Torso

[0153] 30 Electric motor (rotary motor)

[0154] 31 Stator

[0155] 32 stator core

[0156] 34 Yoke

[0157] 35 teeth

[0158] 36. Grooves

[0159] 37 Fixed surface

[0160] 40 rotors

[0161] 50 Compression Mechanism

[0162] 61 First convex part

[0163] 62 Second convex part

[0164] 63 recess

Claims

1. A rotary motor, arranged inside a housing (21) having a cylindrical body (22), characterized in that: The rotary electric motor includes a stator (31) and a rotor (40). The stator (31) is arranged inside the body (22) and has a stator core (32) and a coil (33). The stator core (32) has a cylindrical yoke (34) and teeth (35) extending radially inward from the yoke (34) and arranged circumferentially along the yoke (34). The coil (33) is arranged in a slot (41) formed between two adjacent teeth (35) in the circumferential direction. The rotor (40) is arranged inside the stator core (32) and rotates around the rotation axis. On the outer surface (36, 37) of the stator core (32), which is the outer side of the radial direction, a groove (36) extending axially along the yoke (34) is formed. When viewed from a cross-section orthogonal to the stated axis, A first protrusion (61) that bends outward in the radial direction and a recess (63) that bends inward in the radial direction are formed in the groove (36). The shortest length between the peripheral wall of the groove (41) and the first protrusion (61) is shorter than the length between the portion of the groove (36) other than the first protrusion (61) and the peripheral wall of the groove (41).

2. The rotary motor according to claim 1, characterized in that: When viewed from a cross-section orthogonal to the stated axis, A second protrusion (62) is formed in the groove (36), the second protrusion (62) is connected to the portion other than the groove (36) in the outer side surface (36, 37) and bends outward in the radial direction.

3. The rotary motor according to claim 1 or 2, characterized in that: When viewed from a cross-section orthogonal to the stated axis, The first protrusion (61) and the recess (63) are connected to each other by a smooth curve.

4. The rotary electric motor according to any one of claims 1 to 3, characterized in that: When viewed from a cross-section orthogonal to the stated axis, Let the maximum radial length between the groove (36) and the inner surface of the torso (22) be D. When the length of the groove (36) in the direction orthogonal to the radial direction is set to W, It satisfies: 2.5×D≤W≤5.0×D.

5. The rotary electric motor according to any one of claims 1 to 4, characterized in that: When viewed from a cross-section orthogonal to the stated axis, Let T be the length of the tooth (35) in the direction orthogonal to the radial direction. When the shortest length between the peripheral wall of the groove (41) and the outer side (36, 37) is set as d1, It satisfies: T≤1.7×d1.

6. The rotary electric motor according to any one of claims 1 to 5, characterized in that: The groove (36) is formed on the radially outer side of the tooth (35) in the outer surface (36, 37).

7. A compressor, characterized in that: The compressor includes: The rotary electric motor according to any one of claims 1 to 5; and Compression mechanism (50) driven by the rotary motor.

8. A refrigeration device, characterized in that: The refrigeration device includes the rotary motor as described in any one of claims 1 to 5.

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