Compressor and refrigeration device

Abstract

To provide a compressor capable of preventing generation of a leakage current.SOLUTION: The compressor includes a casing (20), a compression mechanism (30), a drive shaft (40), and a motor (50). The casing stores refrigerating machine oil. The compression mechanism compresses the refrigerant housed inside the casing. The drive shaft drives the compression mechanism. The motor has a stator (51) and rotates the drive shaft. The refrigerating machine oil mixed with the refrigerant in the casing separates into a first layer (L1) and a second layer (L2) in the stopped state. The second layer is positioned above the first layer. An upper end (H2) of the first layer is located below a lower end (H1) of the stator.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This invention relates to a compressor and a refrigeration device. [Background technology]

[0002] Patent Document 1 (JP 2024-13789 A) discloses a refrigeration system using a scroll compressor. Hydrofluorocarbon (HFC) refrigerants have traditionally been used in refrigeration systems. However, in recent years, the use of propane (R290) refrigerant has been increasing in response to European F-gas regulations and other global environmental protection efforts. Summary of the Invention [Problem to be solved by the invention]

[0003] When R290 refrigerant is used instead of HFC refrigerant, the amount of refrigerant that dissolves in the refrigeration oil increases, and depending on the conditions, leakage current may increase. [Means for solving the problem]

[0004] A compressor according to a first aspect has a casing, a compression mechanism, a drive shaft, and a motor. The casing stores refrigeration oil. The compression mechanism compresses a refrigerant contained within the casing. The drive shaft drives the compression mechanism. The motor has a stator and rotates the drive shaft. Refrigeration oil mixed with the refrigerant within the casing separates into a first layer and a second layer when the compressor is stopped. The second layer is located above the first layer. The upper end of the first layer is located below the lower end of the stator.

[0005] With this configuration, when the motor is stopped, the refrigerant oil mixed with the refrigerant separates into a first layer and a second layer, and the upper end of the first layer is located below the lower end of the stator. Therefore, when the motor is stopped, the stator is less likely to be immersed in the refrigerant oil, which prevents leakage current.

[0006] A compressor according to a second aspect is the compressor according to the first aspect, wherein the liquid density of the first layer is greater than the liquid density of the second layer. The liquid density is calculated by dividing the mass of the mixed liquid of the refrigerant and the refrigeration oil by the volume.

[0007] A compressor according to a third aspect is the compressor according to the first or second aspect, wherein the volume resistivity of the second layer is 1.0×10 10 Ω·m or more.

[0008] A compressor according to a fourth aspect is the compressor according to any one of the first aspect to the third aspect, wherein the concentration of the refrigerating machine oil in the first layer is higher than the concentration of the refrigerating machine oil in the second layer.

[0009] A compressor according to a fifth aspect is the compressor according to any one of the first aspect to the fourth aspect, wherein the refrigerant is a natural refrigerant.

[0010] A compressor according to a sixth aspect is the compressor according to the fifth aspect, wherein the refrigerant is a single refrigerant made of hydrocarbon or a mixed refrigerant containing hydrocarbon.

[0011] A compressor according to a seventh aspect is the compressor according to the sixth aspect, wherein the refrigerant is propane.

[0012] A compressor according to an eighth aspect is the compressor according to any one of the first aspect to the seventh aspect, wherein the refrigerating machine oil is an immiscible oil that is immiscible with the refrigerant.

[0013] A compressor according to a ninth aspect is the compressor according to the eighth aspect, wherein the refrigerating machine oil contains any one of polyalkylene glycol, polyvinyl ether, and polyol ester.

[0014] A compressor according to a tenth aspect is the compressor according to the ninth aspect, wherein the refrigerating machine oil is a mono-ol type polyalkylene glycol.

[0015] A refrigeration device according to an eleventh aspect includes the compressor according to any one of the first to tenth aspects. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a refrigerant circuit diagram showing the configuration of a refrigeration device of the present embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view showing the configuration of a compressor. [Figure 3] FIG. 1 shows a two-layer separation region. [Figure 4] FIG. 2 is a vertical cross-sectional view showing the configuration of a compressor in a state where a two-layer separation region is formed. [Figure 5] FIG. 10 is another vertical cross-sectional view showing the configuration of the compressor in a state where a two-layer separation region is formed. DETAILED DESCRIPTION OF THE INVENTION

[0017] In the following description, expressions indicating directions such as "up" and "down" are used as appropriate, and these refer to the directions when the refrigeration apparatus 100 is installed and in normal use. For example, the up-down direction is the vertical direction. The vertical direction is the direction parallel to the direction of gravity.

[0018] (1) Overall Configuration of the Refrigeration Device 100 As shown in Fig. 1, the refrigeration system 100 has a refrigerant circuit 100a filled with a refrigerant. The refrigerant circuit 100a has a compressor 10, a radiator 3, a pressure reduction mechanism 4, and an evaporator 5. The compressor 10 is a scroll compressor. The pressure reduction mechanism 4 is, for example, an expansion valve. The refrigerant circuit 100a performs a vapor compression refrigeration cycle.

[0019] The refrigeration system 100 is an air conditioner. The air conditioner may be a dedicated cooling system, a dedicated heating system, 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 100 may be a water heater, a chiller unit, a cooling device that cools the air inside a storage unit, or the like. A cooling device cools the air inside a refrigerator, a freezer, a container, or the like.

[0020] (2) Compressor 10 As shown in FIG. 2, the compressor 10 includes a casing 20, a compression mechanism 30, a drive shaft 40, and a motor 50.

[0021] (2-1) Casing 20 The casing 20 is formed in a vertically long cylindrical shape and configured as a sealed dome type. The casing 20 houses the motor 50 and the compression mechanism 30.

[0022] An oil reservoir 21 is provided at the bottom of the casing 20. Refrigeration oil is stored in the oil reservoir 21. A suction pipe 12 is connected to the top of the casing 20. A discharge pipe 13 is connected to the body of the casing 20.

[0023] A housing 27 is fixed to the casing 20. The housing 27 is fixed inside the casing 20 by, for example, shrink fitting. The housing 27 is disposed above the motor 50. The compression mechanism 30 is disposed above the housing 27. The inlet end of the discharge pipe 13 is located between the motor 50 and the housing 27.

[0024] A recess 53 is formed in the housing 27. The recess 53 is formed by recessing a part of the upper surface of the housing 27. An upper bearing 27a is provided below the recess 53.

[0025] An oil drain passage 27b is provided in the housing 27. The oil drain passage 27b is a passage for draining the lubricating oil that has flowed into the recess 53 to the outside of the housing 27. The upstream end of the oil drain passage 27b is connected to the recess 53. An oil return member 56 is disposed downstream of the oil drain passage 27b.

[0026] The oil return member 56 guides downward the lubricating oil that is discharged from the recess 53 toward the oil discharge passage 27b. Below the oil return member 56, a guide plate 57 is provided.

[0027] The guide plate 57 guides the lubricating oil discharged from the oil return member 56 to the oil return passage 35 of the motor 50. The guide plate 57 is formed from a tapered plate material whose opening width narrows from top to bottom. The lower part of the oil return member 56 is inserted into the upper part of the guide plate 57. The lower part of the guide plate 57 extends so as to pass through the gap between the casing 20 and the coil part of the motor 50, and the gap in the oil return passage 35.

[0028] (2-2) Compression mechanism 30 The compression mechanism 30 includes a fixed scroll 60 and a movable scroll 70. The fixed scroll 60 is fixed to the upper surface of the housing 27. The movable scroll 70 is disposed between the fixed scroll 60 and the housing 27.

[0029] The fixed scroll 60 has a fixed end plate 61, a fixed side wrap 62, and an outer peripheral wall 63. The outer peripheral wall 63 is formed in a substantially cylindrical shape. The outer peripheral wall 63 stands on the outer edge of the front surface (the lower surface in FIG. 2) of the fixed side end plate 61.

[0030] The fixed side wrap 62 is formed in a spiral shape and is provided upright inside the outer peripheral wall 63 of the fixed side end plate 61.

[0031] The fixed side end plate 61 is located on the outer periphery side and is formed continuously with the fixed side wrap 62. The tip end surface of the fixed side wrap 62 and the tip end surface of the outer periphery wall 63 are formed to be substantially flush with each other. The fixed scroll 60 is fixed to the housing 27.

[0032] The movable scroll 70 has a movable end plate 71, a movable side wrap 72, and a boss portion 73. The movable side wrap 72 is formed in a spiral shape. The movable side wrap 72 is formed on the upper surface of the movable side end plate 71. The movable side wrap 72 meshes with the fixed side wrap 62.

[0033] The boss portion 73 is formed at the center of the lower surface of the movable-side end plate 71. The eccentric portion 42 of the drive shaft 40 is inserted into the boss portion 73, and the drive shaft 40 is connected thereto.

[0034] An Oldham coupling 45 is provided on the upper part of the housing 27. The Oldham coupling 45 prevents the movable scroll 70 from rotating on its axis.

[0035] The compression mechanism 30 has a fluid chamber S into which the refrigerant flows. The fluid chamber S is formed between the fixed scroll 60 and the movable scroll 70. The movable scroll 70 is disposed so that the movable wrap 72 meshes with the fixed wrap 62 of the fixed scroll 60. Here, the lower surface of the outer peripheral wall 63 of the fixed scroll 60 serves as the surface facing the movable scroll 70. In addition, the upper surface of the movable end plate 71 of the movable scroll 70 serves as the surface facing the fixed scroll 60.

[0036] An intake port 64 is formed in the outer peripheral wall 63 of the fixed scroll 60. The intake port 64 opens near the end of the fixed side wrap 62. The downstream end of the intake pipe 12 is connected to the intake port 64.

[0037] A discharge port 65 is formed in the center of the fixed side end plate 61 of the fixed scroll 60. The discharge port 65 opens in the upper surface of the fixed side end plate 61 of the fixed scroll 60. The high-pressure gas refrigerant discharged from the discharge port 65 flows through a passage (not shown) formed in the housing 27 into the upper space 24 below the housing 27 and above the motor 50.

[0038] The recess 53 of the housing 27 communicates with the oil supply passage 16 of the drive shaft 40 via the inside of the boss portion 73 of the movable scroll 70. When high-pressure lubricating oil is supplied to the recess 53, a high pressure equivalent to the discharge pressure of the compression mechanism 30 acts on the recess 53. The high pressure of the recess 53 presses the movable scroll 70 against the fixed scroll 60.

[0039] An oil passage 55 is formed inside the housing 27 and the fixed scroll 60. The inlet end of the oil passage 55 communicates with the recess 53 of the housing 27. The outlet end of the oil passage 55 opens to the opposing surface of the fixed scroll 60. The oil passage 55 supplies high-pressure lubricating oil in the recess 53 to the opposing surface between the movable end plate 71 of the movable scroll 70 and the outer peripheral wall 63 of the fixed scroll 60.

[0040] (2-3) Drive shaft 40 The drive shaft 40 extends in the vertical direction along the central axis of the casing 20. The drive shaft 40 has a main shaft portion 41 and an eccentric portion .

[0041] The eccentric portion 42 is provided at the upper end of the main shaft portion 41. The lower portion of the main shaft portion 41 is rotatably supported by the lower bearing 22. The lower bearing 22 is fixed to the inner circumferential surface of the casing 20. For example, a positive displacement pump 23 is provided in the lower bearing 22. The upper portion of the main shaft portion 41 passes through the housing 27 and is rotatably supported by the upper bearing 27a of the housing 27.

[0042] A balance weight 18 is provided on the drive shaft 40. The balance weight 18 is disposed in the upper space 24 above the rotor 52 of the motor 50.

[0043] An oil supply passage 16 is formed inside the drive shaft 40. The oil supply passage 16 extends vertically from the lower end to the upper end of the drive shaft 40. The lower end of the drive shaft 40 is connected to a pump 23. The lower end of the pump 23 is immersed in an oil reservoir 21. As the drive shaft 40 rotates, the pump 23 draws up lubricating oil from the oil reservoir 21 and transports it to the oil supply passage 16. The oil supply passage 16 supplies the lubricating oil from the oil reservoir 21 to the sliding surfaces between the lower bearing 22 and the drive shaft 40, the sliding surfaces between the upper bearing 27a and the drive shaft 40, and the sliding surfaces between the boss portion 73 and the drive shaft 40. The oil supply passage 16 opens to the upper end surface of the drive shaft 40 and supplies the lubricating oil above the drive shaft 40.

[0044] (2-4) Motor 50 The motor 50 includes a stator 51 and a rotor 52 .

[0045] The stator 51 is fixed to the inner circumferential surface of the casing 20. Coils 51a are wound in a concentrated manner around teeth (not shown) of the stator 51.

[0046] The rotor 52 is disposed inside the stator 51. The drive shaft 40 passes through the rotor 52. The rotor 52 is fixed to the drive shaft 40. The rotor 52 is formed with rotor holes 52a that pass through in the axial direction. A plurality of the rotor holes 52a are formed at intervals in the circumferential direction.

[0047] (3) Refrigerants and refrigeration oils In this embodiment, the refrigerant used in the compressor 10 is propane (R290). The refrigerant is not limited to propane, as long as it is a single refrigerant made of a hydrocarbon or a mixed refrigerant containing a hydrocarbon. The hydrocarbon may be selected from the group consisting of propane, butane, and isobutane, for example. The refrigerant may also be a natural refrigerant other than a hydrocarbon. The natural refrigerant may include, for example, at least one of carbon dioxide, ammonia, and water.

[0048] In this embodiment, the refrigeration oil is a monool-type polyalkylene glycol oil (PAG oil).

[0049] The polyalkylene glycol is, for example, polyethylene glycol, polypropylene glycol, or a copolymer compound of polyethylene glycol and polypropylene glycol.

[0050] In this embodiment, the refrigeration oil used in the compressor 10 is a mono-ol polyalkylene glycol, which is an incompatible oil. An incompatible oil is incompatible with the refrigerant. A mono-ol polyalkylene glycol is a polyalkylene glycol having one hydroxyl group at its terminal. The refrigeration oil is not limited to a mono-ol polyalkylene glycol, as long as it is an incompatible oil containing either a polyalkylene glycol, a polyvinyl ether, or a polyol ester. Hereinafter, the mono-ol polyalkylene glycol, which is the refrigeration oil used in the compressor 10, will be referred to as a "PAG oil."

[0051] As shown in Figures 3 and 4, when R-290 is mixed into PAG oil, the mixture separates into two layers, a first layer L1 and a second layer L2, depending on the R-290 and temperature conditions. When the compressor 10 is stopped, the mixture separates into two layers, the first layer L1 and the second layer L2. The second layer L2 is located above the first layer L1. In the first layer L1, the PAG oil content is higher than the R-290 content. In the second layer L2, the R-290 content is higher than the PAG oil content. Therefore, the liquid density of the first layer L1 is higher than that of the second layer L2. Here, the liquid density is the mass of the mixture of R-290 and PAG oil divided by the volume.

[0052] The concentration of PAG oil in the first layer L1 is greater than the concentration of PAG oil in the second layer L2. The concentration of PAG oil corresponds to the content (wt%) of PAG oil in the mixture. Specifically, the concentration of PAG oil is the mass of PAG oil contained in the mixture divided by the mass of the mixture. The density of PAG oil is greater than the density of propane. Therefore, the density of the mixture in the first layer L1 is greater than the density of the mixture in the second layer L2.

[0053] The volume resistivity of the second layer L2 is 1.0×10 10 Ω·m or more. Volume resistivity is a physical property that indicates the volume resistance per unit volume of the test object. The lower the volume resistivity, the lower the electrical insulation. Volume resistivity is measured at room temperature of 25°C in accordance with IEC60247.

[0054] An upper end H2 of the first layer L1 is located below a lower end H1 of the stator 51. More specifically, the lower end H1 of the stator 51 is the lower end of the coil 51a that is wound around the stator 51 in a concentrated manner.

[0055] The upper end H3 of the second layer L2 may be located above the lower end H1 of the stator 51, as shown in Fig. 4. The upper end H3 of the second layer L2 may be located below the lower end H1 of the stator 51, as shown in Fig. 5.

[0056] (4) Driving behavior The basic operation of the compressor 10 will now be described. In Fig. 2, when the motor 50 is operated, the drive shaft 40 to which the rotor 52 is fixed is driven to rotate. Furthermore, the movable scroll 70 is prevented from rotating by the Oldham coupling 45, and therefore orbits about the axis of the drive shaft 40.

[0057] When the movable scroll 70 orbits, the refrigerant is compressed in the fluid chamber S. The high-pressure gas refrigerant compressed in the fluid chamber S is discharged from the discharge port 65 and flows into the upper space 24 through a passage (not shown) formed in the housing 27.

[0058] A portion of the refrigerant that flows out into the upper space 24 flows into the motor 50 and flows downward along the inner circumferential surface of the casing 20. The refrigerant that flows out of the motor 50 flows toward the upper space 24 through rotor holes 52a formed in the rotor 52. This flow of refrigerant can cool the motor 50.

[0059] The high-pressure gas refrigerant flowing in the upper space 24 is discharged to the outside of the casing 20 via the discharge pipe 13 .

[0060] As the drive shaft 40 rotates, the high-pressure lubricating oil in the oil reservoir 21 is sucked up by the pump 23 , flows upward through the oil supply passage 16 of the drive shaft 40 , and flows out from the opening at the upper end of the eccentric portion 42 of the drive shaft 40 .

[0061] The lubricating oil that flows out from the opening at the upper end of the eccentric portion 42 of the drive shaft 40 flows into the inside of the boss portion 73 of the movable scroll 70 .

[0062] The lubricating oil supplied to the boss portion 73 flows into the recessed portion 53 of the housing 27 through the gap between the eccentric portion 42 of the drive shaft 40 and the boss portion 73. As a result, the recessed portion 53 of the housing 27 becomes under high pressure corresponding to the discharge pressure of the compression mechanism 30. The high pressure in the recessed portion 53 presses the movable scroll 70 against the fixed scroll 60.

[0063] The lubricating oil flowing out from the opening at the upper end of the eccentric portion 42 of the drive shaft 40 spreads over the sliding surface of the Oldham coupling 45, lubricating the Oldham coupling 45. The lubricating oil also lubricates the thrust sliding surface on which the fixed scroll 60 and the movable scroll 70 slide.

[0064] After lubricating each part, the lubricating oil is discharged and returned to the oil reservoir 21. The guide plate 57 guides the lubricating oil discharged from the oil return member 56 to the oil return passage 35 of the motor 50.

[0065] (5) Features (5-1) R290 refrigerant dissolves more readily in refrigeration oil (PAG oil in this embodiment) than HFC refrigerants. In particular, when the outside air temperature is low and the refrigerant accumulates, a larger amount of refrigerant dissolves in the refrigeration oil. When the amount of refrigerant dissolving in the refrigeration oil increases, the amount of the mixture of refrigeration oil and refrigerant that accumulates at the bottom of the compressor casing also increases.

[0066] Furthermore, if R290 dissolves in refrigeration oil, it may cause problems such as abnormal wear due to a decrease in the viscosity of the refrigeration oil. For this reason, it is desirable to use polyalkylene glycol (PAG) oil, which has a higher viscosity index than other oil types. The viscosity index is the degree to which the viscosity of refrigeration oil changes with temperature.

[0067] However, PAG oil has a lower volume resistivity than other oil types. For example, the volume resistivity of PAG oil is 1 / 1000 of the volume resistivity of polyvinyl alcohol (PVE) oil. Low volume resistivity means poor electrical insulation. Therefore, if the amount of the mixture of R290 and PAG oil increases during stagnation and the stator 51 of the compressor 10 is immersed in the PAG oil, leakage current may increase.

[0068] In this embodiment, when the compressor 10 is stopped, the mixed liquid separates into two layers: a first layer L1 and a second layer L2. The second layer L2 is located above the first layer L1. The upper end H2 of the first layer L1 is located below the lower end H1 of the stator 51. Therefore, even if the amount of R-290 dissolved in the PAG oil increases in a so-called stagnation state and the amount of mixed liquid accumulating at the bottom of the casing 20 of the compressor 10 increases, the stator 51 is not immersed in the first layer L1, which contains a large amount of PAG oil. This prevents leakage current from occurring.

[0069] (5-2) The liquid density of the first layer is greater than the liquid density of the second layer. The liquid density is the mass of the mixture of the refrigerant and the refrigerating machine oil divided by the volume.

[0070] (5-3) The volume resistivity of the second layer L2 is 1.0 × 10 10 In this case, even if the stator 51 is immersed in the second layer L2, the occurrence of leakage current can be suppressed.

[0071] (5-4) The concentration of the refrigerating machine oil in the first layer is greater than the concentration of the refrigerating machine oil in the second layer.

[0072] (5-5) The refrigerant is a natural refrigerant.

[0073] (5-6) The refrigerant is a single refrigerant made of hydrocarbon or a mixed refrigerant containing hydrocarbon.

[0074] (5-7) The refrigerant is propane.

[0075] (5-8) Refrigerating machine oil is an incompatible oil that is incompatible with the refrigerant.

[0076] (5-9) The refrigerating machine oil contains any one of polyalkylene glycol, polyvinyl ether, and polyol ester.

[0077] (5-10) The refrigerating machine oil is a mono-ol type polyalkylene glycol.

[0078] (6) Variations In the above embodiment, only PAG oil is used as the refrigerating machine oil, but this is not particularly limited. The refrigerating machine oil may be a mixture of PAG oil and other oils. For example, the refrigerating machine oil may be a mixture of PAG oil and polyoxyethylene (POE) oil. In this case, the POE oil content is preferably 40 to 80 mass%.

[0079] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Industrial Applicability]

[0080] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for compressors and refrigeration devices. [Explanation of symbols]

[0081] 10: Compressor 20: Casing 30: Compression mechanism 40: Drive shaft 50: Motor 51: Stator 100: Refrigeration equipment 100a: Refrigerant circuit L1: 1st layer L2: 2nd layer [Prior art documents] [Patent documents]

[0082] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-13789

Claims

1. a casing (20) for storing refrigeration oil; a compression mechanism (30) that compresses a refrigerant housed inside the casing; a drive shaft (40) that drives the compression mechanism; a motor (50) having a stator (51) for rotating the drive shaft; Equipped with The refrigeration oil mixed with the refrigerant in the casing separates into a first layer (L1) and a second layer (L2) located above the first layer in a stopped state, The upper end (H2) of the first layer is located below the lower end (H1) of the stator. Compressor.

2. With respect to a liquid density obtained by dividing a mass of a mixed liquid of the refrigerant and the refrigerating machine oil by a volume, the liquid density of the first layer is greater than the liquid density of the second layer. The compressor according to claim 1 .

3. The volume resistivity of the second layer is 1.0×10 １０ Ω·m or more, The compressor according to claim 1 .

4. The concentration of the refrigerating machine oil in the first layer is greater than the concentration of the refrigerating machine oil in the second layer. The compressor according to any one of claims 1 to 3.

5. The refrigerant is a natural refrigerant. The compressor according to any one of claims 1 to 3.

6. The refrigerant is a single refrigerant made of hydrocarbon or a mixed refrigerant containing hydrocarbon. The compressor according to claim 5.

7. The refrigerant is propane. The compressor according to claim 6.

8. The refrigerating machine oil is an incompatible oil that is incompatible with the refrigerant, The compressor according to any one of claims 1 to 3.

9. The refrigerating machine oil contains any one of polyalkylene glycol, polyvinyl ether, and polyol ester. The compressor according to claim 8.

10. The refrigerating machine oil is a monool-type polyalkylene glycol. The compressor according to claim 9.

11. A refrigeration device comprising the compressor according to any one of claims 1 to 3.

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