Rotary electric machine

Abstract

To provide a rotary electric machine in which deterioration of a magnetic characteristic is suppressed and passage resistance of a passage through which a fluid passes is suppressed.SOLUTION: In an outer surface (36, 37) which is an outer surface in a radial direction of a stator core (32) of a rotary electric machine, a groove (36) extending in an axis direction is formed. In cross sectional view orthogonal to the axis direction, the groove (36) has a first projection (61) curved outwardly in the radial direction and a recess (63) curved inwardly in the radial direction formed therein, and the shortest length between a circumferential wall surface of a slot (41) and the first projection (61) is shorter than a length between the circumferential wall surface of the slot (41) and a portion of the groove (36) excluding the first projection (61).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] TECHNICAL FIELD This disclosure relates to rotating electrical machines. [Background technology]

[0002] In the rotating electric machine disclosed in Patent Document 1, cutouts are formed on the radial outer surface of the stator core as flow paths for a coolant. In this rotating electric machine, the distance between the cutouts and the bases of the teeth is shortened to increase thermal resistance, thereby reducing the heat transferred from the welding points to the teeth when the stator core and casing are fixed by welding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-278673 Summary of the Invention [Problem to be solved by the invention]

[0004] In a refrigeration system that operates in a refrigeration cycle, when the pressure inside the compressor is high during operation, it is preferable for the refrigeration oil to have a high viscosity, as this reduces the fluidity of the refrigeration oil inside the compressor and ensures a sufficient amount of oil in the oil reservoir.

[0005] Here, the refrigeration oil in the compressor passes through the notches and is stored again in the oil reservoir. The higher the viscosity of the refrigeration oil, the greater the flow resistance when passing through the notches. Therefore, flow resistance can be reduced by increasing the flow area of ​​the notches (the cross-sectional area perpendicular to the extension direction of the notches). However, increasing the flow area creates thin sections in the stator core, which narrows the magnetic path width and makes it more susceptible to magnetic saturation. Magnetic saturation can increase iron loss and potentially reduce the efficiency of the rotating electrical machine.

[0006] An object of the present disclosure is to provide a rotating electric machine that suppresses deterioration of magnetic characteristics and suppresses flow path resistance of a flow path through which a fluid passes. [Means for solving the problem]

[0007] A first aspect of the present disclosure is A rotating electric machine disposed inside a casing (21) having a cylindrical body (22), a stator (31) disposed inside the body (22), the stator (31) having a tubular yoke (34), a stator core (32) having a plurality of teeth (35) extending from the yoke (34) toward the inside in the radial direction of the yoke (34) and aligned in the circumferential direction of the yoke (34), and a coil (33) disposed in a slot (41) formed between two of the teeth (35) adjacent to each other in the circumferential direction; a rotor (40) disposed inside the stator core (32) and rotating around a rotation axis; A groove (36) extending in the axial direction of the yoke portion (34) is formed on outer surfaces (36, 37) that are the radially outer surfaces of the stator core (32), In a cross-sectional view perpendicular to the axial direction, The groove (36) is formed with a first convex portion (61) curved outward in the radial direction and a concave portion (63) curved inward in the radial direction, The shortest length between the peripheral wall surface of the slot (41) and the first convex portion (61) is shorter than the length between the part of the groove (36) excluding the first convex portion (61) and the peripheral wall surface of the slot (41).

[0008] In the first aspect, a flow path extending in the axial direction is formed between the groove (36) and the inner surface of the body portion (22). Here, for example, when a refrigeration oil with a relatively high viscosity flows through this flow path, it is preferable to increase the hydraulic diameter of the flow path to reduce the flow resistance of the refrigeration oil. Increasing the hydraulic diameter increases the flow path area, which is the cross-sectional area perpendicular to the extension direction of the flow path. As a result, the outer surface (36, 37) of the stator core (32) is reduced accordingly, resulting in a relatively thin portion of the stator core (32) as viewed in the cylindrical axis direction (i.e., a portion where the length between the groove (36) and the peripheral wall surface of the slot (41) is relatively short). In such a thin portion, the width of the magnetic path through which magnetic flux is generated becomes narrow, causing magnetic saturation, which increases iron loss and reduces the efficiency of the rotating electric machine.

[0009] Therefore, in the first aspect, a first protrusion (61) is formed in the groove (36). The first protrusion (61) is formed so as to protrude radially outward from the groove (36) in a cross section perpendicular to the axial direction. This prevents the stator core (32) from having a narrow magnetic path width. Furthermore, the recess (63) is formed so as to recess radially inward, thereby preventing a reduction in the flow path area. This prevents a decrease in the efficiency of the rotating electric machine and reduces the flow path resistance of the fluid.

[0010] The second aspect is the first aspect, In a cross-sectional view perpendicular to the axial direction, The groove (36) is formed with a second protrusion (62) that is continuous with the outer surface (36, 37) except for the groove (36) and that curves outward in the radial direction.

[0011] In the second aspect, the formation of the second protrusions (62) allows the flow of magnetic flux to be smooth. Furthermore, compared with a case where the second protrusions (62) are not formed, the area that does not function as a magnetic path can be reduced, resulting in a larger flow path area and reduced material costs. Furthermore, in a case where the second protrusions (62) are not formed, the area of ​​the radially outer surface of the stator core (32) that contacts the inner surface of the trunk portion (22) increases, resulting in increased pressure loss. However, in the second aspect, this increase in pressure loss can be suppressed.

[0012] The third aspect is the first or second aspect, In a cross-sectional view perpendicular to the axial direction, The first convex portion (61) and the concave portion (63) are connected to each other by a smooth curve.

[0013] In the third aspect, the first convex portion (61) and the concave portion (63) are connected by a smooth curve, thereby making it possible to reduce the flow path resistance to the fluid flowing through the flow path.

[0014] A fourth aspect is any one of the first to third aspects, In a cross-sectional view perpendicular to the axial direction, The maximum length in the radial direction between the groove (36) and the inner surface of the body portion (22) is D, When the length of the groove (36) in the direction perpendicular to the radial direction is W, 2.5×D≦W≦5.0×D Meet the following.

[0015] In the fourth aspect, the groove (36) is formed so 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) perpendicular to the radial direction satisfy the above-mentioned relationship, thereby achieving the same effect as in the first aspect.

[0016] A fifth aspect is any one of the first to fourth aspects, In a cross-sectional view perpendicular to the axial direction, The length of the tooth portion (35) in a direction perpendicular to the radial direction is defined as T, When the shortest length between the peripheral wall surface of the slot (41) and the outer side surface (36, 37) is d1, T≦1.7×d1 Meet the following.

[0017] In the fifth aspect, the first convex portion (61) is formed so that the length T of the tooth portion (35) in a direction perpendicular to the radial direction and the shortest length d1 between the peripheral wall surface of the slot (41) and the outer surface (36, 37) satisfy the above formula, thereby achieving the same effect as in the first aspect.

[0018] A sixth aspect is any one of the first to fifth aspects, The grooves (36) are formed on the outer surfaces (36, 37) radially outward of the teeth (35).

[0019] In the sixth aspect, when the stator core 32 is viewed in the axial direction, the region where the teeth 35 are formed has a longer radial length than the portion where the teeth 35 are not formed (i.e., the portion where only the yoke 34 is formed). By providing the grooves 36 at such positions, the same effect as in the first aspect can be obtained.

[0020] A seventh aspect is a compressor including the rotating electric machine according to any one of the first to sixth aspects, and a compression mechanism (50) driven by the rotating electric machine.

[0021] In the seventh aspect, the flow resistance of the refrigeration oil stored in the compressor (20) can be reduced, and a decrease in the efficiency of the compressor (20) can be suppressed.

[0022] An eighth aspect is a refrigeration system including the rotating electric machine according to any one of the first to sixth aspects.

[0023] In the eighth aspect, it is possible to suppress a decrease in the efficiency of the rotating electric machine, and also to suppress a decrease in the efficiency of the refrigeration device. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a piping configuration diagram of a refrigerant circuit provided in a refrigeration device of this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a cross section along the axial direction of the compressor. [Figure 3] FIG. 3 is a schematic diagram showing a cross section perpendicular to the axial direction of the compressor. [Figure 4] FIG. 4 is an enlarged view of a part of FIG. [Figure 5] FIG. 5 is a graph showing the relationship between the ratio of the length of the tooth in the direction perpendicular to the radial direction to the length of the minimum magnetic path width, and the efficiency of the rotating electrical machine. [Figure 6] FIG. 6 is a graph showing the relationship between the flow path area and the ratio of the length of the groove in the direction perpendicular to the radial direction to the length in the radial direction. [Figure 7] FIG. 7 is a graph showing the relationship between the ratio of the length of the groove in the direction perpendicular to the radial direction to the length in the radial direction, and the length of the minimum magnetic path width. [Figure 8] FIG. 8 is a graph showing the relationship between the ratio of the length of the groove in the direction perpendicular to the radial direction to the length in the radial direction, and the hydraulic diameter of the oil flow path. [Figure 9] FIG. 9 is a schematic cross-sectional view of a stator core according to a modified example, which corresponds to FIG. [Figure 10] FIG. 10 is a schematic cross-sectional view of a stator core according to a modified example, which corresponds to FIG. [Figure 11] FIG. 11 is a schematic cross-sectional view of a stator core according to a modified example, which corresponds to FIG. [Figure 12] FIG. 12 is a schematic cross-sectional view of a stator core according to a modified example, which corresponds to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical concept of the present disclosure. Since the drawings are intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding.

[0026] (1) Overview of the refrigeration system A rotating electric machine (30) of the present disclosure is applied to a refrigeration system (1). As shown in FIG. 1, the refrigeration system (1) has a refrigerant circuit (1a) filled with a refrigerant. The refrigerant circuit (1a) has a compressor (20), a radiator (2), a pressure reduction mechanism (3), and an evaporator (4). The pressure reduction mechanism (3) is an expansion valve. The refrigerant circuit (1a) performs a vapor compression refrigeration cycle.

[0027] In the refrigeration cycle, the refrigerant compressed by the compressor (20) dissipates heat to the air in the radiator (2). The refrigerant that has dissipated heat is reduced in pressure by the pressure reducing mechanism (3) and evaporated in the evaporator (4). The evaporated refrigerant is drawn into the compressor (20).

[0028] The refrigeration system (1) is an air conditioner. The air conditioner may be a cooling-only unit, a heating-only unit, or an air conditioner that switches between cooling and heating. In this case, the air conditioner has a switching mechanism (e.g., a four-way switching valve) that switches the refrigerant circulation direction. The refrigeration system (1) may be a water heater, a chiller unit, a cooling device that cools the air inside a storage unit, or the like. The cooling device cools the air inside a refrigerator, a freezer, a container, or the like. The expansion mechanism is composed of an electronic expansion valve, a thermostatic expansion valve, an expander, or a capillary tube.

[0029] (2) Compressor 2, the compressor (20) is a rotary fluid machine and includes a casing (21), an electric motor (30), a drive shaft (28), and a compression mechanism (50).

[0030] (2-1) Casing The casing (21) accommodates the electric motor (30), the drive shaft (28), and the compression mechanism (50). The casing (21) is a hermetically sealed container. The interior of the casing (21) is filled with high-pressure refrigerant discharged from the compression mechanism (50).

[0031] The casing (21) is made of a metal material. The casing (21) has a body (22), a bottom (23), and a top (24). The body (22) is a tubular member made of metal. The body (22) has a cylindrical inner surface on the radially inner side. Openings are formed at both ends of the body (22) in the axial direction. In this embodiment, the axial direction of the body (22) coincides with the vertical direction. The bottom (23) closes the lower opening of the body (22). The top (24) closes the upper opening of the body (22).

[0032] (2-2) Electric motor As shown in Fig. 2, the electric motor (30) is disposed above the compression mechanism (50). As shown in Fig. 3, the electric motor (30) has a stator (31) and a rotor (40). The electric motor (30) is an example of the rotating electric machine (30) of the present disclosure.

[0033] The stator (31) is disposed inside the body portion (22). The stator (31) includes a stator core (32) and a coil (33).

[0034] The stator core 32 has a cylindrical yoke portion 34 and a plurality of (nine in this example) teeth 35 extending radially inward from the yoke portion 34 and aligned in the circumferential direction of the yoke portion 34. The stator core 32 is formed by stacking electromagnetic steel sheets in the cylindrical axis direction of the yoke portion 34.

[0035] The stator core 32 may be made of a soft magnetic material other than electromagnetic steel sheet. For example, the stator core 32 may be made of a material including an amorphous alloy, a nanocrystalline material, or a powder magnetic core. The stator core 32 may be a unitary core or a divided core. A unitary core is a core that is not divided in a direction perpendicular to the axial direction. A divided core is a core that is divided in a direction perpendicular to the axial direction.

[0036] The coil 33 is wound around the teeth 35. The coil 33 is disposed in a slot 41 formed between two circumferentially adjacent teeth 35 of the yoke 34. The slot 41 is formed to extend in the axial direction. In this embodiment, a plurality of slots 41 (nine in this embodiment) are formed.

[0037] The rotor (40) is disposed inside the stator core (32). The rotor (40) rotates about its rotation axis. The rotor (40) is fixed to a drive shaft (28) configured to be rotatable about its rotation axis. In other words, the rotor (40) is configured to be rotatable about its rotation axis. The rotor (40) is formed in a cylindrical shape. A rotor core of the rotor (40) is formed with a plurality of through holes (42) (six in this example). Permanent magnets are disposed in the through holes (42). In this embodiment, the direction of the rotation axis of the rotor (40) coincides with the vertical direction. Furthermore, in a cross section perpendicular to the axial direction of the yoke portion (34), the rotation axis of the rotor (40) coincides with the center of the stator core (32).

[0038] In the following description, the cylindrical axis direction of the yoke portion 34 may be referred to as the "axial direction." A direction perpendicular to the cylindrical axis direction of the yoke portion 34 may be referred to as the "radial direction." In addition, in the direction perpendicular to the cylindrical axis direction of the yoke portion 34, a direction from the center of the stator core 32 toward the trunk portion 22 may be referred to as the "radial outer direction," and a direction from the trunk portion 22 toward the center of the stator core 32 may be referred to as the "radial inner direction." In addition, a direction around the cylindrical axis direction of the yoke portion 34 may be referred to as the "circumferential direction."

[0039] The operation frequency of the electric motor (30) is controlled by an inverter device. In other words, the compressor (20) is an inverter type compressor with a variable operation frequency.

[0040] (2-3) Drive shaft The drive shaft (28) extends vertically along the cylindrical axis of the casing (21). The drive shaft (28) is driven to rotate by an electric motor (30). The drive shaft (28) is rotatably supported by a bearing (29).

[0041] (2-4) Compression mechanism The compression mechanism (50) includes a rotary fluid machine. The compression mechanism (50) includes a cylinder (51) and a piston (52) provided inside the cylinder (51). A cylinder chamber (53) is formed between the inner peripheral surface of the cylinder (51) and the outer peripheral surface of the piston (52). In the cylinder chamber (53), the piston (52) driven by the drive shaft (28) compresses the fluid.

[0042] (2-5) Intake pipe and discharge pipe The compressor (20) has a suction pipe (45) and a discharge pipe (46). The suction pipe (45) passes radially through the body (22) and communicates with the cylinder chamber (53). Low-pressure refrigerant in the refrigerant circuit (1a) is drawn into the cylinder chamber (53) through the suction pipe (45). The discharge pipe (46) passes axially through the top (24) and communicates with the interior space of the casing (21). The refrigerant compressed by the compression mechanism (50) flows through the oil flow path (S1) of the electric motor (30), and is then sent to the refrigerant circuit (1a) through the discharge pipe (46).

[0043] (3) Issues regarding the oil flow path formed between the groove on the outer surface of the stator core and the inner surface of the body An oil reservoir (R) for storing refrigeration oil is formed in the lower part of the casing (21) (see FIG. 2). The refrigeration oil in the oil reservoir (R) is sucked up by a pump provided at the lower end of the drive shaft (28) and then supplied to sliding parts of the compression mechanism (50). When the compressor (20) is operating, the refrigeration oil in the oil reservoir moves above the electric motor (30) in the casing (21) together with the refrigerant discharged from the compression mechanism (50), passes through an oil flow path (S1) formed between the groove (36) and the inner surface of the body part (22), and is stored again in the oil reservoir (R). In other words, the refrigerant circuit (1a) of the present disclosure is filled with refrigerant and refrigeration oil.

[0044] Here, when the refrigerant charged in the refrigerant circuit (1a) is a carbon dioxide refrigerant, which is a natural refrigerant, it needs to be pressurized higher than other refrigerants (for example, R32, which is an HFC refrigerant). In this case, if the viscosity of the refrigerating machine oil in the compressor is relatively low, the fluidity of the refrigerating machine oil increases, making it difficult for the refrigerating machine oil to return to the oil reservoir (R).

[0045] Therefore, although the fluidity of the refrigerating oil can be suppressed by using a refrigerating oil with a relatively high viscosity, it is necessary to suppress the flow path resistance (pipe resistance) of the oil flow path (S1).If the flow path resistance of the oil flow path (S1) is high, the refrigerating oil with a relatively high viscosity will have difficulty returning to the oil reservoir (R).

[0046] It has been found that the value of flow resistance decreases as the hydraulic diameter of the oil flow path (S1) increases. The hydraulic diameter correlates with the size of the flow path cross-sectional area of ​​the oil flow path (S1). Specifically, the hydraulic diameter is expressed by (hydraulic diameter) = 4 × (flow path cross-sectional area) / (wetted perimeter). The wetted perimeter is the circumferential length of the inner circumferential surface (wall surface) of the flow path cross-section. Thus, when the wetted perimeter is constant, the hydraulic diameter increases as the flow path cross-sectional area of ​​the flow path (S1) increases. Therefore, when the wetted perimeter is constant, the flow path resistance can be reduced by increasing the flow path cross-sectional area of ​​the oil flow path (S1).

[0047] However, increasing the cross-sectional area of ​​the oil flow path (S1) results in a relatively thin portion of the stator core (32). That is, the length between the outer surfaces (36, 37) of the stator core (32) and the peripheral wall surfaces of the slots (41) is reduced as viewed in the axial direction. In such a portion, the width through which magnetic flux passes is narrowed, which makes magnetic saturation more likely to occur and increases iron loss. Increased iron loss reduces the efficiency of the electric motor (the efficiency of the rotating electrical machine). In response to this issue, the present embodiment configures the stator core (32) to suppress an increase in iron loss while reducing the flow resistance of the oil flow path (S1).

[0048] (4) Details of the stator core The configuration of the stator core (32) will be described below with reference to Fig. 4. Unless otherwise specified, the shape of the stator core (32) will be described in terms of a cross section perpendicular to the axial direction as viewed from the front (as viewed from the front of Fig. 4).

[0049] The outer surface (36, 37) of the stator core (32) (in other words, the outer peripheral edge of the stator core (32)) has a plurality of fixing surfaces (37) and a plurality of grooves (36) formed alternately and continuously in the circumferential direction of the stator core (32). The inner surface (in other words, the inner peripheral edge of the stator core (32)) of the stator core (32) includes the peripheral wall surfaces of the slots (41) and the radially inner surfaces of the teeth (35). The peripheral wall surfaces of the slots (41) are surfaces that form the peripheral walls of the slots (41). Specifically, the peripheral wall surfaces of the slots (41) include the mutually facing surfaces of two circumferentially adjacent teeth (35) and the radially inner surface of the yoke (34) sandwiched between the two teeth (35).

[0050] (4-1) Fixed surface The fixing surface (37) is the outer surface of the stator core (32) fixed in the body portion (22). In other words, the fixing surface (37) is a surface that contacts the inner surface of the body portion (22). The fixing surface (37) does not have to be in direct contact with the inner surface of the body portion (22). A predetermined intervening member (not shown) may be provided between the inner surface of the body portion (22) and the fixing surface (37). The intervening member is, for example, a resin member or a ceramic member. The fixing surface (37) may also be welded to the body portion (22). When the fixing surface (37) and the body portion (22) are welded, a gap that does not serve as an oil flow path may be formed between the fixing surface (37) and the inner surface of the body portion (22). The gap that does not serve as an oil flow path is a gap whose hydraulic diameter is sufficiently smaller than the hydraulic diameter of the oil flow path (S1) formed between the groove (36) and the inner surface of the body portion (22). For example, a gap that does not become an oil flow path is a gap whose hydraulic diameter is 1 / 100 or less of the hydraulic diameter of the oil flow path (S1) formed between the groove (36) and the inner surface of the body portion (22).

[0051] (4-2) Groove The grooves (36) are recessed radially inward on the outer surface of the stator core (32) to form an oil flow path (S1) through which refrigeration oil passes between the grooves (36) and the inner surface of the body portion (22). In a cross section perpendicular to the axial direction, the grooves (36) are located radially outward of the teeth (35) on the outer surfaces (36, 37) of the stator core (32). In other words, the grooves (36) and the teeth (35) are adjacent to each other in the radial direction.

[0052] In this embodiment, the groove (36) is not covered with a predetermined member and is exposed to the oil flow path (S1). In other words, in this embodiment, the groove (36) is the outer surface of the stator (31). It is desirable that the groove (36) is exposed and not covered with a predetermined member. When the groove (36) is covered with a predetermined member, it is desirable that the area of ​​the member, as viewed in the axial direction, is sufficiently smaller than the area of ​​the oil flow path (S1). For example, when the groove (36) is covered with a predetermined member, it is desirable that the area of ​​the member, as viewed in the axial direction, is 10% or less of the area of ​​the oil flow path (S1). The predetermined member is, for example, a varnish or a resin member. It is desirable that the groove (36) does not include a curve that curves radially outward, and it is desirable that the groove (36) only includes a curve that curves radially inward, from the viewpoint of increasing the hydraulic diameter of the oil flow path (S1).

[0053] The length of the grooves 36 in a direction perpendicular to the radial direction is longer than the length of the teeth 35 in a direction perpendicular to the radial direction. Specifically, the length of the grooves 36 in a direction perpendicular to the radial direction is defined as length W. The length of the teeth 35 in a direction perpendicular to the radial direction is defined as length T. The length W is longer than the length T. If an imaginary line passing through the rotational axis of the rotor 40 and the circumferential midpoint of the teeth 35 is defined as a first radial line, the grooves 36 and the teeth 35 are formed symmetrically with respect to the first radial line. In other words, the length W is the length of the grooves 36 in a direction perpendicular to the first radial line, and the length T is the length of the teeth 35 in a direction perpendicular to the first radial line.

[0054] The groove 36 has a first convex portion 61, a second convex portion 62, and a concave portion 63. In the present embodiment, the second convex portion 62, the concave portion 63, the first convex portion 61, the concave portion 63, the first convex portion 61, the concave portion 63, and the second convex portion 62 are formed from one end to the other end of the groove 36 in the circumferential direction. The first convex portion 61, the second convex portion 62, and the concave portion 63 are formed across both ends of the stator core 32 in the axial direction.

[0055] (4-2-1) First convex part The first convex portion (61) curves radially outward. In other words, the first convex portion (61) is formed so as to bulge from the radially inner side toward the radially outer side as viewed in the axial direction. In other words, the first convex portion (61) is formed so as to bulge from the stator core (32) toward the trunk portion (22) as viewed in the axial direction. In other words, the first convex portion (61) is formed so as to bulge from the slot (41) toward the oil flow path (S1) as viewed in the axial direction. In yet another way, the first convex portion (61) is formed so that a part of the groove (36) bulges smoothly radially outward as viewed in the axial direction. Note that a minute straight line or plane may be formed in a part of the first convex portion (61) for convenience in manufacturing the stator core (32). In other words, the first convex portion (61) does not have to be strictly composed of only curved portions in a cross section perpendicular to the axial direction.

[0056] When a cross section perpendicular to the axial direction is viewed from the front, a predetermined position of the groove (36) is designated as P, and a predetermined position on the peripheral wall surface of the slot (41) is designated as Q. The first convex portion (61) is formed at a position where the length between P and Q is shortest. The portion where the length between P and Q is shortest is the thinnest portion of the yoke portion (34). In this thin portion, the magnetic path width for magnetic flux flow is narrowest. The first convex portion (61) is formed in the groove (36) at such a portion of the yoke portion (34) where the magnetic path width is narrowest.

[0057] Q is located at the connection portion of the peripheral wall surface of the slot (41) between the tooth portion (35) and the yoke portion (34). In other words, Q is located at the base of the yoke portion (34) of the tooth portion (35). P is located at the position where the distance between P and Q is shortest from the position of Q. In this embodiment, one groove (36) has two portions where the distance between P and Q is shortest. In other words, two first protrusions (61) are formed per groove (36).

[0058] In other words, the teeth (35) located radially inside each groove (36) form the peripheral wall surfaces of two circumferentially adjacent slots (41). Of the two first protrusions (61) formed in each groove (36), one first protrusion (61) includes a position P where the length between it and a position Q on the peripheral wall surface of one of the two slots (41) is shortest, and the other first protrusion (61) includes a position P where the length between it and a position Q on the peripheral wall surface of the other slot (41) is shortest. In other words, each groove (36) has one point where the length between P and Q is shortest with respect to the peripheral wall surface of one of the two circumferentially adjacent slots (41), and one point where the length between P and Q is shortest with respect to the peripheral wall surface of the other slot (41).

[0059] The two first protrusions 61 formed in one groove 36 are disposed symmetrically with respect to the first radial line. The shortest distance between the first protrusion 61 and the peripheral wall surface of the slot 41 is only required to be shorter than the distance between the portion of the groove 36 excluding the first protrusion 61 and the peripheral wall surface of the slot 41. For example, the point where the distance between the first protrusion 61 and the peripheral wall surface of the slot 41 is shortest may be a predetermined range of the first protrusion 61, a single point on the first protrusion 61, or two or more points on the first protrusion 61. The predetermined range may be a part or the entirety of the first protrusion 61. For example, if the shape of the base of the yoke portion (34) of the tooth portion (35) and the shape of the first convex portion (61) are arc-shaped with the same center, the length between the peripheral wall surface of the slot (41) within a specified range of the first convex portion (61) will be the shortest.

[0060] When the apex of the first convex portion (61) is defined as P', the longer the length between P' and Q, the more the narrowing of the magnetic path width can be prevented, but the smaller the flow path cross-sectional area of ​​the oil flow path (S1) becomes, and the flow path resistance increases. Therefore, in the electric motor (30) of this embodiment, the length d1 between the first convex portion (61) and the peripheral wall surface of the slot (41) is configured to be shorter than the length d2 between the portion of the groove (36) excluding the first convex portion (61) and the peripheral wall surface of the slot (41).

[0061] That is, the length d1 is the shortest length between the groove 36 and the peripheral wall surface of the slot 41. Here, as shown in FIG. 5 , when the relationship between the efficiency of the rotating electric machine and the ratio of T to d1 (T / d1) was investigated, it was found that the efficiency of the rotating electric machine decreases as T / d1 increases, and drops sharply when T / d1 is around 1.7. This shows that the efficiency of the rotating electric machine is good when T / d1 is 1.7 or less. Therefore, the first convex portion 61 of this embodiment is formed so as to satisfy T≦1.7×d1.

[0062] (4-2-2) Second convex part 4, the second protrusions (62) smoothly connect to the fixing surface (37) in a cross section perpendicular to the axial direction and curve radially outward. In this embodiment, the second protrusions (62) are formed at both circumferential ends of each groove (36). That is, in this embodiment, two second protrusions (62) are formed per groove (36).

[0063] The second convex portions (62) are curved radially outward. In other words, the second convex portions (62) are formed so as to bulge from the radially inner side toward the radially outer side as viewed in the axial direction. In other words, the second convex portions (62) are formed so as to bulge from the stator core (32) toward the trunk portion (22) as viewed in the axial direction. In further words, the second convex portions (62) are formed so that the circumferential ends of the grooves (36) bulge smoothly radially outward when viewed from the front in a cross section perpendicular to the axial direction. Note that a minute straight line or flat surface may be formed in part of the second convex portions (62) for convenience in manufacturing the stator core (32). In other words, the second convex portions (62) do not have to be strictly composed of only curved portions in a cross section perpendicular to the axial direction.

[0064] (4-2-3) Recess The recess (63) is curved radially inward in a cross section perpendicular to the axial direction. In other words, the recess (63) is formed so as to bulge radially inward from the radially outer side when viewed in the axial direction. In other words, the recess (63) is formed so as to bulge from the body portion (22) toward the stator core (32).

[0065] The recessed portion (63) is formed between two first protrusions (61). The recessed portion (63) is also formed between adjacent first protrusions (61) and second protrusions (62). Specifically, the recessed portion (63) is formed so as to connect two adjacent first protrusions (61). The recessed portion (63) is formed so as to connect adjacent first protrusions (61) and second protrusions (62).

[0066] In this embodiment, three recesses 63 are formed in one 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 to the second protrusion 62 by a smooth curve.

[0067] In other words, the recesses 63 are connected to adjacent surfaces in the circumferential direction by curved lines that are free of bends and sharp points. Note that "smooth" means "free of bends and sharp points." In other words, the recesses 63 are connected to adjacent surfaces in the circumferential direction by curved lines that are free of bends and sharp points.

[0068] In this embodiment, each of the three recesses (63) is formed in an elliptical arc shape with its major axis, minor axis, and center aligned with the first radial line.

[0069] Note that a small straight line or a small flat line may be formed in a part of the recess 63 for convenience in manufacturing the stator core 32. In other words, the recess 63 does not have to be strictly composed of only curved portions in a cross section perpendicular to the axial direction.

[0070] (5) Relationship between the length of the groove in the direction perpendicular to the radial direction and the length in the radial direction The grooves (36) of this embodiment are formed based on the relationship between the length W in the direction perpendicular to the radial direction and the length D in the radial direction.

[0071] In a cross section perpendicular 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 portion 22. In other words, the length D corresponds to the radial length between an imaginary line extending the fixing surface 37 of the stator core 32 and the deepest part of the groove 36. In further words, in a cross section perpendicular to the axial direction, the length D corresponds to the radial length between an imaginary line circumscribing the stator core 32 and the deepest part of the groove 36. The deepest part of the groove 36 indicates the position of the groove 36 closest to the inside in the radial direction.

[0072] In the present embodiment, the deepest portion of the groove 36 is located at a position that overlaps with the first radial line. Therefore, in a cross section perpendicular to the axial direction, the length D corresponds to the distance between the point where the first radial line intersects with a virtual line that circumscribes the stator core 32, and the point where the groove 36 intersects with the first radial line.

[0073] In this embodiment, assuming that the shape of the flow path cross section of the oil flow path (S1) is formed to be approximately semi-elliptical, the optimum ratio (W / D) of the length W in the direction perpendicular to the radial direction to the length D was determined. The optimum ratio is determined from the viewpoints of the flow path area of ​​the oil flow path (S1), the minimum magnetic path width, and the hydraulic diameter of the oil flow path (S1).

[0074] As shown in Figure 6, the flow path area increases as the value of W / D increases. Also, as shown in Figure 7, the minimum magnetic path width decreases as the value of W / D increases, reaching a roughly constant value when the value of W / D is 5 or more. Also, as shown in Figure 8, the hydraulic diameter increases as the value of W / D increases, and begins to decrease when the value of W / D is around 5. From these, we selected a W / D that would provide good results for the flow path area of ​​the oil flow path (S1), the minimum magnetic path width, and the hydraulic diameter of the oil flow path (S1).

[0075] 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.

[0076] (6) Features (6-1) Feature 1 In the present embodiment, the grooves (36) of the stator core (32) are formed with first convex portions (61) that curve radially outward and concave portions (63) that curve radially inward. In a cross-sectional view perpendicular to the axial direction, the shortest length between the peripheral wall surface of the slots (41) and the first convex portions (61) is shorter than the length between the peripheral wall surface of the slots (41) and a portion of the grooves (36) excluding the first convex portions (61).

[0077] According to this embodiment, the first protrusions (61) are formed in the grooves (36) that define the oil flow passages (S1) at the thin portions of the stator core (32). This prevents the magnetic path width from narrowing at the thin portions even when the flow area of ​​the oil flow passages (S1) is increased. As a result, it is possible to prevent an increase in iron loss and a decrease in the efficiency of the rotating electrical machine.

[0078] In addition, since the recesses (63) are formed radially inward, a decrease in the flow path area can be suppressed. In this way, it is possible to suppress a decrease in the efficiency of the rotating electric machine while suppressing the flow path resistance of the oil flow path (S1). It was found that when the flow path area of ​​the present embodiment is compared with that of the conventional technology in which the first protrusions (61) are not formed, with the minimum magnetic path width and hydraulic diameter fixed, the flow path area of ​​the present embodiment is 1.5 times larger than that of the conventional technology.

[0079] (6-2) Feature 2 In this embodiment, in a cross-sectional view perpendicular to the axial direction, the groove (36) has a second convex portion (62) that is continuous with the portion of the outer surface (36, 37) excluding the groove (36) and curves radially outward.

[0080] The formation of the second convex portions (62) allows the flow of magnetic flux to be smooth. Furthermore, compared with the case where the second convex portions (62) are not formed, the area that does not function as a magnetic path can be reduced, resulting in a larger flow path area of ​​the oil flow path (S1). Additionally, if the second convex portions (62) are not formed in the grooves (36), the fixing surface (37) of the stator core (32) increases, and the area of ​​the radially outer surface of the stator core (32) that contacts the inner surface of the trunk portion (22) increases, resulting in an increase in pressure loss. However, the electric motor (30) of this embodiment can suppress an increase in pressure loss.

[0081] (6-3) Feature 3 In this embodiment, in a cross section perpendicular to the axial direction, the first convex portion (61) and the concave portion (63) are connected to each other by a smooth curve.

[0082] The first convex portion (61) and the concave portion (63) are connected by a smooth curve, thereby reducing the flow resistance relative to the flow area of ​​the oil flow path (S1), thereby allowing even refrigeration oil with a relatively high viscosity to easily flow through the oil flow path (S1).

[0083] (6-4) Feature 4 In this embodiment, when the maximum radial length between the groove (36) and the inner surface of the body portion (22) is D and the length of the groove (36) in a direction perpendicular to the radial direction is W, 2.5×D≦W≦5.0×D In this way, by forming the grooves 36 so that the length W of the grooves 36 in the direction perpendicular to the radial direction satisfies the above numerical range, it is possible to suppress an increase in iron loss and a decrease in the efficiency of the rotating electrical machine.

[0084] (6-5) Feature 5 In this embodiment, when viewed in a cross section perpendicular to the axial direction, the length of the tooth portion (35) in a direction perpendicular to the radial direction is defined as T, and the shortest length between the peripheral wall surface of the slot (41) and the outer side surfaces (36, 37) is defined as d1. T≦1.7×d1 By forming the groove (36) so that the shortest length d1 between the peripheral wall surface of the slot (41) and the outer side surfaces (36, 37) satisfies the above numerical range, it is possible to suppress an increase in iron loss and a decrease in the efficiency of the rotating electrical machine.

[0085] (6-6) Feature 6 In this embodiment, the grooves 36 are formed on the outer surfaces 36, 37 radially outward of the teeth 35. As such, when viewed from the axial direction, the region of the stator core 32 where the teeth 35 are formed has the longest radial length of the stator core 32. By providing the grooves 36 in such positions, it is possible to suppress an increase in iron loss and a decrease in the efficiency of the rotating electrical machine.

[0086] (7) Variations The above embodiment may be configured as follows.

[0087] As shown in FIGS. 9 to 11 , the recesses (63) formed in the groove (36) may be curved radially inward as viewed in the axial direction, and may be curved in a circular or elliptical arc shape. Specifically, as shown in FIG. 9 , the groove (36) may be formed so that each of the three recesses (63) overlaps the circumference of a single circle (two-dot chain line). In this case, the center of the circle (two-dot chain line) tangent to the three recesses (63) is located on the first radial line. As shown in FIG. 10 , the three recesses (63) may be formed so that each of the three recesses (63) overlaps the circumference of an ellipse (two-dot chain line). In this case, the minor axis of the ellipse (two-dot chain line) tangent to the three recesses (63) overlaps the first radial line. In FIG. 11 , the recesses (63) formed in the groove (36) are formed only between the first convex portion (61) and the second convex portion (62). The grooves (36) may be formed so that one recess (63) overlaps the circumference of one circle (broken line).

[0088] 12, the stator core 32 may be formed so that the radially inner sides of the slots 41 are closed when viewed from the axial direction. In other words, the inner surface of the stator core 32 may be formed so as to include the radially inner surfaces of the teeth 35 but not the peripheral wall surfaces of the slots 41.

[0089] The rotating electric machine may be applied to an expander (not shown). For example, the expander is a pressure reduction mechanism (3) of a refrigeration device (1). The expander includes an expansion mechanism and a generator. The generator corresponds to the rotating electric machine of the present disclosure. The expansion mechanism includes, for example, a rotary fluid machine. The generator is disposed vertically above the expansion mechanism.

[0090] The groove 36 does not have to have the second protrusion 62. In other words, both circumferential ends of the groove 36 do not have to be curved radially outward.

[0091] The grooves 36 may be entirely curved when viewed in the axial direction, or may have straight line portions formed in some of the grooves 36. In other words, the grooves 36 may be composed of both curved and straight lines, or may be composed of only curved lines without any straight lines. For example, straight line portions may be formed between both circumferential ends of the grooves 36 and the first convex portions 61, or straight line portions may be formed between the first convex portions 61 and the concave portions 63.

[0092] The groove 36 may be formed entirely of smooth curves and straight lines as viewed in the axial direction, or may be formed entirely of smooth curves. In other words, the groove 36 may be formed without any bends or sharp points.

[0093] The groove 36 may be configured with a combination of non-smooth curves and straight lines when viewed in the axial direction, or may be configured with only non-smooth curves. In other words, the groove 36 may be configured to include bends and sharp points.

[0094] The groove (36) may be configured so as not to include any curved line that curves outward in the radial direction, except for the first convex portion (61).

[0095] The groove (36) may be configured so as not to include any curved line curving outward in the radial direction, except for the first convex portion (61) and the second convex portion (62).

[0096] The groove (36) may be configured to include only curved lines that curve radially inward, excluding the first convex portion (61).

[0097] The groove (36) may be configured to include only curved lines that curve radially inward, excluding the first convex portion (61) and the second convex portion (62).

[0098] The recesses (63) of the stator core (32) may be configured to be formed only between two first protrusions (61), and not between adjacent first protrusions (61) and second protrusions (62).

[0099] The recesses (63) of the stator core (32) may be configured to be formed only between adjacent first protrusions (61) and second protrusions (62), and not between two first protrusions (61).

[0100] The first convex portion (61) and the concave portion (63) of the stator core (32) do not have to be connected to each other by a smooth curve.

[0101] The length W of the groove 36 in the direction perpendicular to the radial direction may be set regardless of the value of the length D in the radial direction.

[0102] The shortest length d1 between the peripheral wall surface of the slot (41) and the outer surface of the stator core (32) may be set regardless of the value of the length T in the direction perpendicular to the radial direction of the tooth portion (35). Furthermore, of the two first protrusions (61) formed in one groove (36), the shortest length d1 between one first protrusion (61) and the peripheral wall surface of the slot (41) may be the same as or different from the shortest length d1 between the other first protrusion (61) and the peripheral wall surface of the slot (41).

[0103] The number of grooves 36 in the stator core 32 may be equal to or less than the number of teeth 35. In other words, the grooves 36 may be formed radially outward of all teeth 35, or may be formed radially outward of one or more teeth 35, with no grooves 36 formed radially outward of the remaining teeth 35.

[0104] In the above description, the rotor (40) is an interior permanent magnet synchronous rotor with permanent magnets arranged therein, but is not limited thereto. For example, the rotor may be a surface permanent magnet synchronous rotor with permanent magnets arranged radially outward, a reluctance rotor in which inductance varies depending on the rotor position, or a squirrel-cage induction rotor in which multiple axially extending conductor bars are connected by end rings and embedded in a core. While the rotor (40) has nine teeth (35), the number may be ten or more, or two or more but eight or fewer. While the rotor (40) has a rotary compression mechanism and expansion mechanism, the number is not limited thereto. The compression mechanism and expansion mechanism may be a scroll fluid machine, a screw fluid machine, or a centrifugal fluid machine.

[0105] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and detail are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments and modifications may be combined or substituted as appropriate as long as the functionality of the subject matter of this disclosure is not impaired. The terms "first," "second," etc., described above, are used to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Industrial Applicability]

[0106] As described above, the present disclosure is useful for rotating electric machines, compressors, and refrigeration devices. [Explanation of symbols]

[0107] 1 Refrigeration equipment 20 Compressor 21 Casing 22 Torso 30 Electric motors (rotating electrical machines) 31 Stator 32 stator core 34 York 35 Teeth 36 Groove 37 Fixed surface 40 rotors 50 Compression mechanism 61 First convex part 62 Second convex part 63 Recess

Claims

1. A rotating electric machine disposed inside a casing (21) having a cylindrical body (22), a stator (31) having a stator core (32) including a cylindrical yoke portion (34) and teeth (35) extending from the yoke portion (34) toward the inside in the radial direction of the yoke portion (34) and arranged in the circumferential direction of the yoke portion (34); and a coil (33) arranged in a slot (41) formed between two of the teeth (35) adjacent to each other in the circumferential direction, the stator (31) being arranged inside the trunk portion (22); a rotor (40) disposed inside the stator core (32) and rotating around a rotation axis; a groove (36) extending in the axial direction of the yoke portion (34) is formed on an outer surface (36, 37) which is the radially outer surface of the stator core (32); In a cross-sectional view perpendicular to the axial direction, The groove (36) is formed with a first convex portion (61) curved outward in the radial direction and a concave portion (63) curved inward in the radial direction, The shortest length between the peripheral wall surface of the slot (41) and the first convex portion (61) is shorter than the length between the peripheral wall surface of the slot (41) and the portion of the groove (36) excluding the first convex portion (61). Rotating electrical machines.

2. In a cross-sectional view perpendicular to the axial direction, The groove (36) is formed with a second protrusion (62) that is continuous with the outer surface (36, 37) except for the groove (36) and that curves outward in the radial direction.

2. A rotating electrical machine according to claim 1.

3. In a cross-sectional view perpendicular to the axial direction, The first convex portion (61) and the concave portion (63) are connected to each other by a smooth curve.

3. A rotating electrical machine according to claim 1 or 2.

4. In a cross-sectional view perpendicular to the axial direction, the maximum length in the radial direction between the groove (36) and the inner surface of the body portion (22) is D; When the length of the groove (36) in a direction perpendicular to the radial direction is W, 2.5 x D ≤ W ≤ 5.0 x D fulfill 3. A rotating electrical machine according to claim 1 or 2.

5. In a cross-sectional view perpendicular to the axial direction, The length of the tooth portion (35) in a direction perpendicular to the radial direction is defined as T, When the shortest length between the peripheral wall surface of the slot (41) and the outer side surface (36, 37) is defined as d1, T≦1.7×d1 fulfill 3. A rotating electrical machine according to claim 1 or 2.

6. The grooves (36) are formed on the outer surfaces (36, 37) radially outward of the teeth (35).

3. A rotating electrical machine according to claim 1 or 2.

7. A rotating electric machine according to claim 1 or 2; a compression mechanism (50) driven by the rotary electric machine.

8. A refrigeration system comprising the rotating electric machine according to claim 1 or 2.

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