Rotating electrical machinery

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] The present disclosure relates to a rotating electrical machine.

Background Art

[0002] In the rotating electrical machine disclosed in Patent Document 1, a notch portion as a refrigerant flow path is formed on the radially outer surface of the stator core. In this rotating electrical machine, by shortening the distance between the notch portion and the root of the teeth, the thermal resistance is increased, and when the stator core and the casing are fixed by welding, the heat transmitted from the welding point to the teeth is reduced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a refrigeration apparatus that performs a refrigeration cycle, when the pressure inside the compressor is high during the operation of the compressor, it is preferable that the refrigeration oil has a high viscosity. This is because the fluidity of the refrigeration oil inside the compressor is suppressed, and the amount of oil in the oil reservoir can be ensured.

[0005] Here, the refrigeration oil inside the compressor passes through the notch portion and is stored again in the oil reservoir. However, the higher the viscosity of the refrigeration oil, the greater the flow path resistance when passing through the notch portion. Therefore, by increasing the flow path area of the notch portion (the cross-sectional area orthogonal to the extending direction of the notch portion), the flow path resistance can be suppressed. However, when the flow path area is increased, a thin portion is generated in the stator core, and in such a thin portion, the magnetic path width becomes narrow and magnetic saturation is likely to occur. When magnetic saturation occurs, there is a risk that the iron loss increases and the efficiency of the rotating electrical machine decreases.

[0006] The purpose of this disclosure is to provide a rotating electromachine that suppresses the deterioration of magnetic properties and suppresses the flow resistance of the fluid passage. [Means for solving the problem]

[0007] The first aspect of this disclosure is, A rotating electric machine, which is positioned inside a casing (21) having a cylindrical body (22), A stator core (32) having a cylindrical yoke portion (34) and a plurality of teeth portions (35) extending radially inward from the yoke portion (34) and arranged circumferentially around the yoke portion (34), and a stator (31) having a coil (33) arranged in a slot (41) formed between two adjacent teeth portions (35) in the circumferential direction, and positioned inside the body portion (22), The stator core (32) is positioned inside the rotor (40) which rotates around its axis of rotation, On the outer surface (36, 37) of the stator core (32), which is the radially outer surface, a groove (36) is formed that extends in the axial direction of the yoke portion (34). In a cross-sectional view perpendicular to the aforementioned axial direction, The groove (36) is formed with a first convex portion (61) that curves outward in the radial direction and a concave portion (63) that curves inward in the radial direction. The shortest distance between the peripheral wall surface of the slot (41) and the first protrusion (61) is 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).

[0008] In the first embodiment, a flow path extending in the axial direction is formed between the groove (36) and the inner surface of the body (22). Here, for example, if a relatively viscous refrigerant oil flows through this flow path, it is preferable to increase the hydraulic diameter of the flow path in order to suppress the flow resistance of the refrigerant 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, and as a result the outer surfaces (36, 37) of the stator core (32) are scraped away, so that the stator core (32) has a relatively thin-walled portion when viewed from the direction of the cylindrical axis (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-walled portion, the magnetic path width in which magnetic flux is formed becomes narrower, resulting in magnetic saturation, which increases iron loss and reduces the efficiency of the rotating electrical machine.

[0009] In the first embodiment, a first protrusion (61) is formed in the groove (36). The first protrusion (61) is formed to protrude radially outward from the groove (36) in a cross-sectional view perpendicular to the axial direction. This suppresses the formation of a portion in the stator core (32) where the magnetic path width is narrowed. In addition, since the recess (63) is formed to be recessed radially inward, a reduction in the flow area can be suppressed. This suppresses a decrease in the efficiency of the rotating electrical machine and also suppresses the flow resistance of the fluid.

[0010] A second aspect is, in the first aspect, In a cross-sectional view perpendicular to the aforementioned axial direction, A second protrusion (62) is formed in the groove (36), which is continuous with the portion of the outer surface (36,37) excluding the groove (36) and curves outward in the radial direction.

[0011] In the second embodiment, the formation of the second protrusion (62) makes the flow of magnetic flux smoother. In addition, compared to the case where the second protrusion (62) is not formed, the area that does not function as a magnetic path can be reduced, and as a result, the flow area can be increased and material costs can be reduced. Furthermore, in the case where the second protrusion (62) is not formed, the area of ​​the radial outer surface of the stator core (32) that is in contact with the inner surface of the body (22) becomes larger, which increases pressure loss, but in the second embodiment, the increase in pressure loss can be suppressed.

[0012] A third aspect is a manifestation of the first or second aspect, In a cross-sectional view perpendicular to the aforementioned axial direction, The first protrusion (61) and the recess (63) are connected to each other by a smooth curve.

[0013] In the third embodiment, the flow resistance to the fluid flowing through the channel can be reduced by connecting the first convex portion (61) and the concave portion (63) with a smooth curve.

[0014] The fourth aspect is one of the first to third aspects, In a cross-sectional view perpendicular to the aforementioned axial direction, Let D be the maximum radial length between the groove (36) and the inner surface of the body portion (22). When the length of the groove (36) in the direction perpendicular to the radial direction is W, 2.5 × D ≤ W ≤ 5.0 × D It satisfies the condition.

[0015] In the fourth embodiment, the same effect as in the first embodiment can be obtained 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 in the direction perpendicular to the radial direction of the groove (36) satisfy the above relationship.

[0016] The fifth aspect is one of the first to fourth aspects, In a cross-sectional view perpendicular to the aforementioned axial direction, Let the length in the direction orthogonal to the radial direction of the tooth portion (35) be T, when the shortest length between the peripheral wall surface of the slot (41) and the outer surfaces (36, 37) is d1, T ≤ 1.7 × d1 is satisfied.

[0017] In the fifth aspect, by forming the first convex portion (61) such that the length T in the direction orthogonal to the radial direction of the tooth portion (35) and the shortest length d1 between the peripheral wall surface of the slot (41) and the outer surfaces (36, 37) satisfy the above formula, the same effect as in the first aspect can be obtained.

[0018] The sixth aspect is any one of the first to fifth aspects, the groove (36) is formed on the outer side in the radial direction of the tooth portion (35) of the outer surfaces (36, 37).

[0019] In the sixth aspect, when the stator core (32) is viewed from the axial direction, the region where the tooth portion (35) is formed has a longer radial length than the portion where the tooth portion (35) is not formed (that is, the portion of only the yoke portion (34)). By providing the groove (36) at such a position, the same effect as in the first aspect can be obtained.

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

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

[0022] The eighth aspect is a refrigeration device including a rotary electric machine according to any one of the first to sixth aspects.

[0023] In the eighth aspect, the decrease in the efficiency of the rotary electric machine can be suppressed, and the decrease in the efficiency of the refrigeration device can be suppressed.

Brief Description of the Drawings

[0024] [Figure 1] Figure 1 is a diagram showing the piping configuration of the refrigerant circuit in the refrigeration system of this embodiment. [Figure 2] Figure 2 is a schematic diagram showing a cross-section of the compressor along its axial direction. [Figure 3] Figure 3 is a schematic diagram showing a cross-section perpendicular to the axial direction of the compressor. [Figure 4] Figure 4 is an enlarged view of a portion of Figure 3. [Figure 5] Figure 5 is a graph showing the relationship between the ratio of the length of the teeth section perpendicular to the radial direction to the length of the minimum magnetic path width and the efficiency of the rotating electrical machine. [Figure 6] Figure 6 is a graph showing the relationship between the ratio of the length perpendicular to the radial direction of the groove to the length in the radial direction, and the flow channel area. [Figure 7] Figure 7 is a graph showing the relationship between the ratio of the length perpendicular to the radial direction of the groove to the length in the radial direction, and the length of the minimum magnetic path width. [Figure 8] Figure 8 is a graph showing the relationship between the ratio of the length perpendicular to the radial direction of the groove to the length in the radial direction, and the hydraulic diameter of the oil flow path. [Figure 9] Figure 9 is a schematic cross-sectional view of a modified stator core corresponding to Figure 3. [Figure 10] Figure 10 is a schematic cross-sectional view of a modified stator core corresponding to Figure 3. [Figure 11] Figure 11 is a schematic cross-sectional view of a modified stator core corresponding to Figure 3. [Figure 12] Figure 12 is a schematic cross-sectional view of a modified stator core corresponding to Figure 3. [Modes for carrying out the invention]

[0025] The embodiments of this disclosure will be described in detail below with reference to the drawings. However, this disclosure is not limited to the embodiments shown below, and various modifications are possible without departing from the technical idea of ​​this disclosure. Since the drawings are for conceptual illustration of this disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.

[0026] (1) Overview of the refrigeration system The rotating electric machine (30) of this disclosure is applied to a refrigeration unit (1). As shown in Figure 1, the refrigeration unit (1) has a refrigerant circuit (1a) filled with refrigerant. The refrigerant circuit (1a) has a compressor (20), a heat sink (2), a pressure reducing mechanism (3), and an evaporator (4). The pressure reducing mechanism (3) is an expansion valve. The refrigerant circuit (1a) performs a vapor compression type refrigeration cycle.

[0027] In the refrigeration cycle, the refrigerant compressed by the compressor (20) releases heat into the air in the heat exchanger (2). The refrigerant that has released heat is depressurized by the pressure reduction mechanism (3) and evaporates in the evaporator (4). The evaporated refrigerant is drawn back into the compressor (20).

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

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

[0030] (2-1) Casing The casing (21) houses the electric motor (30), the drive shaft (28), and the compression mechanism (50). The casing (21) is a completely sealed container. The inside 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 cylindrical member made of metal. The body (22) has a cylindrical inner surface on the radial side. Openings are formed at both ends of the body (22) in the direction of the cylindrical axis. In this embodiment, the direction of the cylindrical axis 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 Figure 2, the electric motor (30) is positioned above the compression mechanism (50). As shown in Figure 3, the electric motor (30) has a stator (31) and a rotor (40). The electric motor (30) is an example of a rotating electric machine (30) of the present disclosure.

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

[0034] The stator core (32) has a cylindrical yoke portion (34) and a plurality of teeth portions (35) (9 in this example) that extend radially inward from the yoke portion (34) and are arranged circumferentially around the yoke portion (34). The stator core (32) is constructed by laminating electrical steel sheets in the direction of the cylindrical axis of the yoke portion (34).

[0035] The stator core (32) may be made of a soft magnetic material other than electrical steel sheet. For example, the stator core (32) may be made of an amorphous alloy, a nanocrystalline material, or a material containing a compacted magnetic core. The stator core (32) may be a single core or a segmented core. A single core is a core that is not divided in a direction perpendicular to the axial direction. A segmented core is a core that is divided in a direction perpendicular to the axial direction.

[0036] The coil (33) is wound around the teeth portion (35). The coil (33) is positioned in a slot (41) formed between two adjacent teeth portions (35) in the circumferential direction of the yoke portion (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 positioned inside the stator core (32). The rotor (40) rotates around its axis of rotation. The rotor (40) is fixed to a drive shaft (28) that is configured to rotate freely around its axis of rotation. In other words, the rotor (40) is configured to rotate freely around its axis of rotation. The rotor (40) is formed in a cylindrical shape. Multiple (six in this example) through holes (42) are formed in the rotor core of the rotor (40). Permanent magnets are placed in the through holes (42). In this embodiment, the direction of the axis of rotation of the rotor (40) coincides with the vertical direction. Also, in a cross-section perpendicular to the axial direction of the yoke portion (34), the axis of rotation of the rotor (40) coincides with the center of the stator core (32).

[0038] In the following explanation, the direction of the yoke (34) in the cylindrical axis direction may be referred to as the "axial direction." The direction perpendicular to the cylindrical axis direction of the yoke (34) may be referred to as the "radial direction." Furthermore, in the direction perpendicular to the cylindrical axis direction of the yoke (34), the direction from the center of the stator core (32) toward the body (22) may be referred to as the "radial outward direction," and the direction from the body (22) toward the center of the stator core (32) may be referred to as the "radial inward direction." Additionally, the direction around the cylindrical axis direction of the yoke (34) may be referred to as the "circumferential direction."

[0039] The electric motor (30) has its operating frequency controlled by an inverter device. In other words, the compressor (20) is an inverter type with a variable operating 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 rotationally driven 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) comprises a rotary-type fluid machine. The compression mechanism (50) includes a cylinder (51) and a piston (52) located inside the cylinder (51). A cylinder chamber (53) is formed between the inner surface of the cylinder (51) and the outer surface of the piston (52). In the cylinder chamber (53), the fluid is compressed by the piston (52), which is driven by the drive shaft (28).

[0042] (2-5) Inhalation pipe and discharge pipe The compressor (20) has an intake pipe (45) and a discharge pipe (46). The intake pipe (45) penetrates the body (22) radially and communicates with the cylinder chamber (53). Low-pressure refrigerant from the refrigerant circuit (1a) is drawn into the cylinder chamber (53) through the intake pipe (45). The discharge pipe (46) penetrates the top (24) axially and communicates with the internal space of the casing (21). The refrigerant compressed by the compression mechanism (50) flows through the oil passage (S1) of the electric motor (30), etc., and is then sent to the refrigerant circuit (1a) from the discharge pipe (46).

[0043] (3) Issues relating to the oil passage 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 refrigerant oil is formed at the bottom of the casing (21) (see 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 then supplied to the sliding part of the compression mechanism (50). When the compressor (20) is operated, the refrigerant oil in the oil reservoir moves along with the refrigerant discharged from the compression mechanism (50) to the upper part of the electric motor (30) inside the casing (21), then passes through an oil passage (S1) formed between the groove (36) and the inner surface of the body (22) and is stored again in the oil reservoir (R). In other words, the refrigerant circuit (1a) of this disclosure contains refrigerant and refrigerant oil.

[0044] Here, if the refrigerant sealed in the refrigerant circuit (1a) is a natural refrigerant such as carbon dioxide, it needs to be at a higher pressure than other refrigerants (for example, HFC refrigerants such as R32). In this case, if the viscosity of the refrigerant oil in the compressor is relatively low, the fluidity of the refrigerant oil will increase, making it difficult for the refrigerant oil to return to the oil reservoir (R).

[0045] Therefore, using a refrigerant oil with relatively high viscosity can suppress the fluidity of the refrigerant oil, but it is necessary to suppress the flow resistance (pipe resistance) of the oil passage (S1). This is because if the flow resistance of the oil passage (S1) is high, the refrigerant oil with 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 as (hydraulic diameter) = 4 × (flow path cross-sectional area) / (wetting edge length). The wetting edge length is the length of the circumference of the inner surface (wall) in the flow path cross-section. Thus, when the wetting edge length is kept constant, the hydraulic diameter increases as the flow path cross-sectional area of ​​the flow path (S1) increases. Therefore, when the wetting edge length is kept constant, flow 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 passage (S1) results in relatively thin sections of the stator core (32). That is, sections where the length between the outer surfaces (36, 37) of the stator core (32) and the peripheral wall surface of the slot (41) is shortened when viewed from the axial direction. In such sections, the width through which the magnetic flux passes becomes narrower, making magnetic saturation more likely and increasing iron loss. Increased iron loss reduces the efficiency of the electric motor (efficiency of the rotating electrical machine). Focusing on these issues, in this embodiment, the stator core (32) is configured to suppress the increase in iron loss while suppressing the flow resistance of the oil passage (S1).

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

[0049] The outer surfaces (36, 37) of the stator core (32) (in other words, the outer peripheral edge of the stator core (32)) have a plurality of fixed surfaces (37) and a plurality of grooves (36) that are alternately and continuously formed in the circumferential direction of the stator core (32). The inner surfaces of the stator core (32) (in other words, the inner peripheral edge of the stator core (32)) include 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 the surfaces that constitute the peripheral wall of the slots (41). Specifically, the peripheral wall surfaces of the slots (41) include the opposing 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 fixed surface (37) is the outer surface of the stator core (32) that is fixed within the body (22). In other words, the fixed surface (37) is the surface that contacts the inner surface of the body (22). Note that the fixed surface (37) does not have to be in direct contact with the inner surface of the body (22), and a predetermined intervening member (not shown) may be provided between the inner surface of the body (22) and the fixed surface (37). The intervening member may be, for example, a resin member or a ceramic member. The fixed surface (37) may also be welded to the body (22). When the fixed surface (37) and the body (22) are welded, there may be a gap between the fixed surface (37) and the inner surface of the body (22) that is not large enough to form an oil passage. A gap that is not large enough to form an oil passage is a gap whose hydraulic diameter is sufficiently small compared to the hydraulic diameter of the oil passage (S1) formed between the groove (36) and the inner surface of the body (22). For example, a gap that does not form an oil passage is a gap with a hydraulic diameter of 1 / 100 or less of the hydraulic diameter of the oil passage (S1) formed between the groove (36) and the inner surface of the body (22).

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

[0052] In this embodiment, the groove (36) is not covered by a predetermined member and is exposed to the oil passage (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 without being covered by a predetermined member. If the groove (36) is covered by a predetermined member, it is desirable that the area of ​​the member is sufficiently smaller than the area of ​​the oil passage (S1) when viewed from the axial direction. For example, if the groove (36) is covered by a predetermined member, it is desirable that the area of ​​the member is 10% or less of the area of ​​the oil passage (S1) when viewed from the axial direction. The predetermined member is, for example, a varnish or a resin member. From the viewpoint of increasing the hydraulic diameter of the oil passage (S1), it is desirable that the groove (36) does not include a curve that curves radially outward, and only includes a curve that curves radially inward.

[0053] The length of the groove (36) in the direction perpendicular to the radial direction is longer than the length of the teeth portion (35) in the direction perpendicular to the radial direction. Specifically, let W be the length of the groove (36) in the direction perpendicular to the radial direction. Let T be the length of the teeth portion (35) in the direction perpendicular to the radial direction. Length W is longer than length T. If we hypothetically draw a line passing through the rotation axis of the rotor (40) and the midpoint of the circumferential direction of the teeth portion (35), and call that line the first radial line, then the groove (36) and the teeth portion (35) are formed symmetrically with respect to the first radial line. In other words, length W is the length of the groove (36) in the direction perpendicular to the first radial line, and length T is the length of the teeth portion (35) in the direction perpendicular to the first radial line.

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

[0055] (4-2-1) First protrusion The first protrusion (61) curves radially outward. In other words, the first protrusion (61) is formed to bulge radially from the radially inward to the radially outward when viewed from the axial direction. In other words, the first protrusion (61) is formed to bulge radially from the stator core (32) toward the body (22) when viewed from the axial direction. In other words, the first protrusion (61) is formed to bulge radially from the slot (41) toward the oil passage (S1) when viewed from the axial direction. In further other words, the first protrusion (61) is formed such that a part of the groove (36) bulges radially outward when viewed from the axial direction. Note that a small straight line or plane formed on a part of the first protrusion (61) due to manufacturing considerations of the stator core (32) may be formed. That is, the first protrusion (61) does not have to be composed strictly of curved portions in a cross section perpendicular to the axial direction.

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

[0057] Q is located on the peripheral wall surface of the slot (41) at the connection point between the teeth portion (35) and the yoke portion (34). In other words, Q is located at the base of the yoke portion (34) of the teeth 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, there are two portions in one groove (36) where the distance between P and Q is shortest. That is, two first protrusions (61) are formed in one groove (36).

[0058] In other words, for each groove (36), the teeth portion (35) located radially inward of the groove (36) constitutes the circumferential wall surfaces of two adjacent slots (41) in the circumferential direction. In the two first protrusions (61) formed in the groove (36), one first protrusion (61) includes a position P where the length between it and position Q on the circumferential 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 position Q on the circumferential wall surface of the other slot (41) is shortest. To put it another way, in each groove (36), there is one location where the length between P and Q is shortest with respect to the circumferential wall surface of one of the two adjacent slots (41) in the circumferential direction, and one location where the length between P and Q is shortest with respect to the circumferential wall surface of the other slot (41).

[0059] The two first protrusions (61) formed in a single groove (36) are arranged symmetrically with respect to a first radial line. The shortest distance between the first protrusion (61) and the peripheral wall surface of the slot (41) is 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 location 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 of the first protrusion (61) or all of it. For example, if the shape of the base of the yoke portion (34) of the teeth portion (35) and the shape of the first protrusion (61) are both arc-shaped with the same center, the distance between the first protrusion (61) and the peripheral wall surface of the slot (41) will be the shortest within a predetermined range.

[0060] When the top of the first protrusion (61) is P', increasing the length between P' and Q suppresses the narrowing of the magnetic path width, but this reduces the flow cross-sectional area of ​​the oil flow path (S1), thus increasing the flow resistance. Therefore, in the electric motor (30) of this embodiment, the length d1 between the first protrusion (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 protrusion (61) and the peripheral wall surface of the slot (41).

[0061] In other words, length d1 is the minimum length between the groove (36) and the peripheral wall surface of the slot (41). Here, as shown in Figure 5, when we investigated the relationship between the efficiency of the rotating electric machine and the ratio of T to d1 (T / d1), we found that as T / d1 increases, the efficiency of the rotating electric machine decreases, and it drops sharply from around 1.7. From this, we found that the efficiency of the rotating electric machine is good when T / d1 is 1.7 or less. Therefore, the first protrusion (61) of this embodiment is formed to satisfy T ≤ 1.7 × d1.

[0062] (4-2-2) Second protrusion As shown in Figure 4, the second protrusion (62) is smoothly continuous with the fixed surface (37) in a cross section perpendicular to the axial direction and curves radially outward. In this embodiment, the second protrusion (62) is formed at both ends in the circumferential direction of each groove (36). That is, in this embodiment, two second protrusions (62) are formed for each groove (36).

[0063] The second protrusion (62) curves radially outward. In other words, the second protrusion (62) is formed to bulge radially outward when viewed from the axial direction. In other words, the second protrusion (62) is formed to bulge radially outward from the stator core (32) when viewed from the axial direction. In further terms, when viewed from the front in a cross section perpendicular to the axial direction, the second protrusion (62) is formed such that the circumferential end of the groove (36) bulges radially outward. It should be noted that a small straight line or plane formed on a part of the second protrusion (62) due to manufacturing considerations of the stator core (32) may be formed. That is, the second protrusion (62) does not have to be composed solely of curved portions in a cross section perpendicular to the axial direction.

[0064] (4-2-3) recess The recess (63) curves radially inward in a cross-section perpendicular to the axial direction. In other words, the recess (63) is formed to bulge radially outward from radially outward to radially inward when viewed from the axial direction. To put it another way, the recess (63) is formed to bulge from the body (22) toward the stator core (32).

[0065] The recess (63) is formed between the two first protrusions (61). Also, the 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). The recess (63) is formed 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 each other by curves that have no bends or sharp points in the circumferential direction. Note that "smooth" means "without bends or sharp points." In other words, the recesses (63) are connected to each other by curves that have no bends or sharp points in the circumferential direction.

[0068] In this embodiment, the three recesses (63) are formed in an elliptical arc shape with the same major axis, minor axis, and center. Furthermore, the three recesses (63) are formed in an elliptical arc shape with the minor axis overlapping the first radial line and the center located on the first radial line.

[0069] Furthermore, a small straight line or plane may be formed in a part of the recess (63) due to manufacturing considerations of the stator core (32). In other words, the recess (63) does not have to be composed solely of curved portions in a cross section perpendicular to the axial direction.

[0070] (5) Relationship between the length of the groove perpendicular to the radial direction and the length in the radial direction The groove (36) in this embodiment is 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 (22). In other words, length D corresponds to the radial length between a line virtually drawn by extending the fixed surface (37) of the stator core (32) and the deepest part of the groove (36). To put it another way, in a cross-section perpendicular to the axial direction, length D corresponds to the radial length between a line virtually drawn as the circumscribed circle of the stator core (32) and the deepest part of the groove (36). The deepest part of the groove (36) is the position of the groove (36) that is closest to the radial interior.

[0072] In this embodiment, the deepest part of the groove (36) coincides with the first radial line. Therefore, in a cross-section perpendicular to the axial direction, length D corresponds to the length between the point where the line representing the circumscribed circle of the stator core (32) intersects with the first radial line, and the point where the groove (36) intersects with the first radial line.

[0073] In this embodiment, assuming that the cross-sectional shape of the oil channel (S1) is formed as a semi-ellipse, the optimal ratio (W / D) of the length W in the direction perpendicular to the radial direction to the length D was determined. The optimal ratio is determined from the viewpoint of the channel area of ​​the oil channel (S1), the minimum magnetic path width, and the hydraulic diameter of the oil channel (S1).

[0074] As shown in Figure 6, the flow path area increases as the W / D value increases. Also, as shown in Figure 7, the minimum magnetic path width decreases as the W / D value increases, and becomes roughly constant when the W / D value is 5 or higher. Furthermore, as shown in Figure 8, the hydraulic diameter increases as the W / D value increases, and begins to decrease from around a W / D value of 5. From these observations, a W / D value was selected that yielded 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) Characteristics (6-1) Feature 1 In this embodiment, the groove (36) of the stator core (32) is formed with a first protrusion (61) that curves radially outward and a recess (63) that curves radially inward. In a cross-sectional view perpendicular to the axial direction, the shortest distance between the peripheral wall surface of the slot (41) and the first protrusion (61) is 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).

[0077] According to this embodiment, a first protrusion (61) is formed in the groove (36) constituting the oil passage (S1) in the portion of the stator core (32) that is thin. This makes it possible to suppress the narrowing of the magnetic path width in the thin portion even when the flow area of ​​the oil passage (S1) is increased. As a result, an increase in iron loss can be suppressed, and a decrease in the efficiency of the rotating electrical machine can be suppressed.

[0078] In addition, since the recess (63) is formed radially inward, a reduction in the flow path area can be suppressed. In this way, the flow resistance of the oil flow path (S1) can be suppressed while suppressing a decrease in the efficiency of the rotating electrical machine. Furthermore, when the minimum magnetic path width length and hydraulic diameter are fixed and the flow path area in the conventional technology, where the first protrusion (61) is not formed, is compared with the flow path area in this embodiment, it was found that the flow path area in this 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 protrusion (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 protrusion (62) makes the flow of magnetic flux smoother. In addition, compared to the case where the second protrusion (62) is not formed, the area that does not function as a magnetic path can be reduced, and as a result, the flow area of ​​the oil passage (S1) can be increased. Furthermore, in the case where the second protrusion (62) is not formed in the groove (36), the fixed surface (37) of the stator core (32) increases, and the area of ​​the radial outer surface of the stator core (32) that is in contact with the inner surface of the body (22) increases, which increases pressure loss. In contrast, the electric motor (30) of this embodiment can suppress the increase in pressure loss.

[0081] (6-3) Feature 3 In this embodiment, 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.

[0082] By connecting the first convex portion (61) and the concave portion (63) with a smooth curve, the flow resistance relative to the flow area of ​​the oil passage (S1) can be reduced. This makes it easier for even relatively viscous refrigeration oil to flow through the oil passage (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 (22) is D, and the length of the groove (36) in the direction perpendicular to the radial direction is W, 2.5 × D ≤ W ≤ 5.0 × D This satisfies the above condition. By forming the groove (36) such that the length W in the direction perpendicular to the radial direction of the groove (36) satisfies the above numerical range, the increase in iron loss can be suppressed, and the decrease in the efficiency of the rotating electrical machine can be suppressed.

[0084] (6-5) Feature 5 In this embodiment, when, in a cross-sectional view perpendicular to the axial direction, the length of the teeth portion (35) in the direction perpendicular to the radial direction is T, and the shortest length between the peripheral wall surface and the outer surface (36,37) of the slot (41) is d1, T ≤ 1.7 × d1 The following conditions are met. By forming the groove (36) such that the shortest length d1 between the peripheral wall surface and the outer surface (36,37) of the slot (41) satisfies the above numerical range, the increase in iron loss can be suppressed, and the decrease in the efficiency of the rotating electrical machine can be suppressed.

[0085] (6-6) Feature 6 In this embodiment, the groove (36) is formed on the radially outer side of the teeth portion (35) of the outer surface (36, 37). When viewed from the axial direction, the region of the stator core (32) where the teeth portion (35) is formed has the longest radial length of the stator core (32). By providing the groove (36) in this position, the increase in iron loss can be suppressed, and the decrease in the efficiency of the rotating electrical machine can be suppressed.

[0086] (7) Variant The above embodiment may also have the following configuration.

[0087] As shown in Figures 9 to 11, when viewed from the axial direction, the recesses (63) formed in the groove (36) only need to be formed curving radially inward, and may be formed to curve in an arc shape or an elliptical arc shape. Specifically, as shown in Figure 9, the groove (36) may be formed such that each of the three recesses (63) overlaps on the circumference of a circle (dash-dot line). In this case, the center of the circle (dash-dot line) tangent to the three recesses (63) is located on the first radial line. Also, as shown in Figure 10, each of the three recesses (63) may be formed so that each of the three recesses (63) overlaps on the circumference of an ellipse (dash-dot line). In this case, the minor axis of the ellipse (dash-dot line) tangent to the three recesses (63) coincides with the first radial line. Furthermore, in Figure 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 as to overlap the circumference of one circle (dashed line) for each recess (63).

[0088] As shown in Figure 12, the stator core (32) may be formed such that the radially inner side of the slot (41) is closed when viewed from the axial direction. In other words, the inner surface of the stator core (32) may be formed to include the radially inner surface of the teeth portion (35) and not include the peripheral wall surface of the slot (41).

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

[0090] The groove (36) does not have to have a second protrusion (62). That is, both ends of the groove (36) in the circumferential direction do not have to be formed to curve radially outward.

[0091] The groove (36) may be entirely composed of curves when viewed from the axial direction, or a straight section may be formed in part of the groove (36). In other words, the groove (36) may be composed of curves and straight lines, or it may be composed only of curves without any straight lines. For example, a straight section may be formed between both ends of the groove (36) in the circumferential direction and the first protrusion (61), or a straight section may be formed between the first protrusion (61) and the recess (63).

[0092] The groove (36) may consist entirely of smooth curves and straight lines when viewed from the axial direction, or it may consist entirely of smooth curves. In other words, the groove (36) may be constructed without any bends or sharp points.

[0093] The groove (36) may consist of non-smooth curves and straight lines when viewed from the axial direction, or it may consist only of non-smooth curves. In other words, the groove (36) may include bends and sharp points.

[0094] The groove (36) may be configured so as not to include any curves that curve radially outward, except for the first protrusion (61).

[0095] The groove (36) may be configured so as not to include any curves that curve radially outward, except for the first protrusion (61) and the second protrusion (62).

[0096] The groove (36) may be configured to include only curves that curve radially inward, except for the first protrusion (61).

[0097] The groove (36) may be configured to include only curves that curve radially inward, except for the first protrusion (61) and the second protrusion (62).

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

[0099] The recess (63) of the stator core (32) may 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 concave portion (63) of the stator core (32) do not necessarily have to be connected to each other by a smooth curve.

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

[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 teeth portion (35). Also, 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 the same as or less than the number of teeth (35). In other words, the grooves (36) may be formed on the radially outer side of all teeth (35), or they may be formed on the radially outer side of one or more teeth (35) and not on the radially outer side of the other teeth (35).

[0104] The above explanation uses the example of an embedded magnet synchronous rotor in which permanent magnets are arranged as the rotor (40), but is not limited to this. For example, it may be a surface magnet synchronous rotor in which permanent magnets are arranged radially outward, or a reluctance type rotor in which the inductance varies depending on the rotor position, or a squirrel-cage induction type rotor in which multiple axially extending conductor bars are connected by end rings and embedded in a core. Also, the example uses the case where there are nine teeth (35), but there may be 10 or more, or 8 or fewer and 2 or more. Furthermore, the example uses the case where the compression mechanism and expansion mechanism are rotary type fluid machines, but is not limited to this. The compression mechanism and expansion mechanism may be scroll type fluid machines, screw type fluid machines, or centrifugal type fluid machines.

[0105] While embodiments and modifications have been described above, it will be understood that a variety of changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, these embodiments and modifications may be combined or substituted as appropriate, as long as they do not impair the functions of the subject matter of this disclosure. The terms “First,” “Second,” etc., used above are used to distinguish the phrases to which these terms are attached, and do not limit the number or order of such phrases. [Industrial applicability]

[0106] As described above, this disclosure is useful for rotating electromachines, compressors, and refrigeration equipment. [Explanation of Symbols]

[0107] 1. Refrigeration equipment 20 Compressors 21 Casing 22 Torso 30. Electric motors (rotating electrical machinery) 31 stata 32 stator cores 34 York section 35 Teeth section 36 Groove 37 Fixed surface 40 rotors 50 Compression mechanism 61 First protrusion 62 Second protrusion 63 recess

Claims

1. A rotating electric machine, which is positioned inside a casing (21) having a cylindrical body (22), A stator core (32) having a cylindrical yoke portion (34) and a plurality of teeth portions (35) extending radially inward from the yoke portion (34) and arranged circumferentially around the yoke portion (34), and a stator (31) having a coil (33) arranged in a slot (41) formed between two adjacent teeth portions (35) in the circumferential direction, and positioned inside the body portion (22), The stator core (32) is positioned inside the rotor (40) which rotates around its axis of rotation, On the outer surface (36, 37) of the stator core (32), which is the radially outer surface, a groove (36) is formed as a fluid passage extending in the axial direction of the yoke portion (34). In a cross-sectional view perpendicular to the aforementioned axial direction, The groove (36) is formed with a first convex portion (61) that curves outward in the radial direction and a concave portion (63) that curves inward in the radial direction. The shortest distance between the peripheral wall surface of the slot (41) and the first protrusion (61) is shorter than the shortest distance between the portion of the groove (36) excluding the first protrusion (61) and the peripheral wall surface of the slot (41). Rotating electrical machinery.

2. In a cross-sectional view perpendicular to the aforementioned axial direction, A second protrusion (62) is formed in the groove (36), which is continuous with the portion of the outer surface (36, 37) excluding the groove (36) and curves outward in the radial direction. The rotating electric machine according to claim 1.

3. In a cross-sectional view perpendicular to the aforementioned axial direction, The first protrusion (61) and the recess (63) are connected to each other by a smooth curve. The rotating electric machine according to claim 1 or 2.

4. In a cross-sectional view perpendicular to the aforementioned axial direction, Let D be the maximum radial length between the groove (36) and the inner surface of the body portion (22). When the length of the groove (36) in the direction perpendicular to the radial direction is W, 2.5 × D ≤ W ≤ 5.0 × D satisfies The rotating electric machine according to claim 1 or 2.

5. In a cross-sectional view perpendicular to the aforementioned axial direction, Let T be the length of the teeth portion (35) in the direction perpendicular to the radial direction. When the shortest length between the peripheral wall surface of the slot (41) and the outer surfaces (36, 37) is defined as d1, T ≤ 1.7 × d1 satisfies The rotating electric machine according to claim 1 or 2.

6. The groove (36) is formed on the radially outer side of the teeth portion (35) among the outer surfaces (36, 37). The rotating electric machine according to claim 1 or 2.

7. A rotating electric machine according to claim 1 or 2, A compressor comprising a compression mechanism (50) driven by the aforementioned rotating electric machine.

8. A refrigeration apparatus comprising a rotating electric machine according to claim 1 or 2.

Images