Compressor and refrigeration cycle device

Abstract

A compressor capable of suppressing wear on sliding parts is provided. The refrigerant is a hydrocarbon refrigerant or a mixed refrigerant containing a hydrocarbon refrigerant. In the oil reservoir (35), the refrigeration oil present at a height below the suction port (71a) has a solution viscosity η of 5.0 mPa·S or more.

Description

[Technical Field]

[0001] The present disclosure relates to a compressor and a refrigeration cycle device. [Background technology]

[0002] Patent Document 1 discloses a refrigeration cycle device. The refrigeration cycle device has a refrigerant circuit. The refrigerant circuit has a compressor, a radiator, an expansion valve, and an evaporator. When the compressor is operated, refrigerant circulates in the refrigerant circuit, and a refrigeration cycle is performed.

[0003] In the compressor, the refrigerant compressed in the compression mechanism flows through the space inside the casing and then flows out from the discharge pipe into the refrigerant circuit, filling the inside of the casing with high-pressure refrigerant.

[0004] An oil reservoir is formed at the bottom of the casing to store refrigeration oil. The refrigeration oil is used to lubricate the sliding parts of the compressor. The refrigeration oil in the oil reservoir is drawn into the suction port of the oil supply pump and supplied to the sliding parts of the bearings and eccentric parts through the oil supply passage in the rotating shaft. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-162986 Summary of the Invention [Problem to be solved by the invention]

[0006] Hydrocarbon refrigerants, such as propane, are used in the refrigerant circuits of refrigeration cycle devices. Hydrocarbon refrigerants are natural refrigerants with extremely low global warming potential. However, like refrigerant oil, hydrocarbon refrigerants have hydrocarbon bonds and a molecular structure similar to that of refrigerant oil, making them easily soluble in refrigerant oil. Therefore, if hydrocarbon refrigerants dissolve in refrigerant oil inside the compressor casing, the dissolving viscosity of the refrigerant oil may decrease. If such refrigerant oil is supplied to the sliding parts of bearings or eccentric parts, the amount of wear on the sliding parts increases.

[0007] An object of the present disclosure is to provide a compressor that can suppress wear of sliding parts. [Means for solving the problem]

[0008] The first aspect relates to a compressor including an electric motor (25, 125), a rotating shaft (30, 130) coupled to the electric motor (25, 125), bearings (44, 45, 152, 156, 157) rotatably supporting the rotating shaft (30, 130), a compression mechanism (40, 140) driven by the rotating shaft (30, 130) and compressing a refrigerant, an oil supply mechanism (70, 170), and a casing (21, 121) that houses the electric motor (25, 125), the rotating shaft (30, 130), the bearings (44, 45, 152, 156, 157), the compression mechanism (40, 140), and the oil supply mechanism (70, 170) and is filled with high-pressure refrigerant discharged from the compression mechanism (40, 140). The rotating shaft (30, 130) has a shaft body (31, 131) and an eccentric portion (32A, 32B, 132) eccentric from the axis of the shaft body (31, 131). The oil supply mechanism (70, 170) includes an oil supply pump (71, 171) having a suction port (71a, 171a) for sucking refrigeration oil from an oil reservoir (35, 135) at the bottom of the casing (21, 121), and an oil supply passage (72, 172) for supplying the oil sucked through the suction port (71a, 171a) to sliding portions of the bearings (44, 45, 152, 156, 157) and the eccentric portion (32A, 32B, 132). The refrigerant is a single refrigerant made of a hydrocarbon refrigerant or a mixed refrigerant containing the hydrocarbon refrigerant. The refrigeration oil is an oil that separates into two layers when the refrigerant pressure is 1.9 MPa and the temperature of the refrigeration oil is 75° C. In the oil reservoir (35, 135), the refrigeration oil present at a height below the suction port (71a, 171a) has a melt viscosity η of 5.0 mPa·S or more.

[0009] In the first aspect, refrigeration oil in the oil reservoir (35, 135) flows through the suction port (71a, 171a) and the oil supply passage (72, 172) and is supplied to the sliding parts of the bearings (44, 45, 152, 156, 157) and the sliding parts of the eccentric parts (32A, 32B, 132). The soluble viscosity η of the refrigeration oil present at or below the height of the suction port (71a, 171a) is 5.0 mPa·S or more. This prevents low-viscosity refrigeration oil from being supplied to the sliding parts. As a result, wear on the sliding parts can be reduced.

[0010] In the second aspect, in the first aspect, the compression mechanism is a rotary compression mechanism (40) having annular cylinders (51A, 51B), annular rollers (52A, 52B) that rotate eccentrically in the cylinders (51A, 51B), and vanes (53A, 53B) for forming compression chambers in the cylinders (51A, 51B).

[0011] In the second aspect, wear of the sliding parts in the rotary compressor can be suppressed.

[0012] In the third mode, when the displacement volume of the rotary compression mechanism (40) is defined as Vc [cc], the solution viscosity η is equal to or less than (−0.00101×Vc+0.12286) / (0.0000146×Vc+0.00505).

[0013] If the solution viscosity of the refrigeration oil becomes too high, the sliding loss of the sliding parts increases, resulting in increased mechanical loss. The sliding loss of the eccentric parts (32A, 32B) is affected by the projected area of ​​the eccentric parts (32A, 32B) when viewed from the radially outside. The projected area of ​​the eccentric parts (32A, 32B) increases as the displacement volume Vc of the rotary compression mechanism (40) increases. As a result of consideration given to the above, the upper limit of the solution viscosity for suppressing the sliding loss of the eccentric parts (32A, 32B) can be expressed by the above function including the displacement volume Vc [cc]. In the third aspect, the solution viscosity η is set to be equal to or less than this upper limit, thereby suppressing the sliding loss of the eccentric parts (32A, 32B) from becoming excessively high.

[0014] In the fourth embodiment, the compression mechanism in the first embodiment is a scroll-type compression mechanism (140) having a fixed scroll (141) and a movable scroll (160).

[0015] In the fourth aspect, wear of the sliding parts in the scroll compressor can be suppressed.

[0016] In a fifth aspect, when the displacement volume of the scroll compression mechanism (140) in the fourth aspect is defined as Vcs [cc], the solution viscosity η is equal to or less than (0.000195×Vcs+0.0696) / 0.00714.

[0017] If the solution viscosity of the refrigeration oil becomes too high, the sliding loss of the sliding parts increases, resulting in increased mechanical loss. Here, the sliding loss of the scroll compressor is dominated by the sliding loss of the bearings. The area of ​​the sliding parts of the bearings increases as the displacement volume Vcs of the scroll compression mechanism (140) increases. As a result of consideration given to the above, the upper limit of the solution viscosity for suppressing the sliding loss of the bearings (152, 156, 157) can be expressed by the above function including the displacement volume Vcs [cc]. In the fifth aspect, the solution viscosity η is set to be equal to or less than this upper limit, thereby suppressing excessively high sliding losses of the sliding parts and eccentric parts.

[0018] In a sixth aspect, in any one of the first to fifth aspects, the refrigerating machine oil contains any one of polyalkylene glycol, polyvinyl ether, and polyvinyl ether.

[0019] In a sixth aspect, the refrigerating machine oil contains polyalkylene glycol, polyvinyl ether, or polyol ester. These refrigerating machine oils are relatively difficult to dissolve hydrocarbon refrigerants in. Therefore, it is possible to prevent the dissolution viscosity of the refrigerating machine oil from becoming excessively low, which would be caused by the hydrocarbon refrigerant dissolving in the refrigerating machine oil.

[0020] In a seventh aspect, in any one of the first to sixth aspects, the refrigerating machine oil contains at least one of a phosphate ester extreme pressure additive, an antioxidant, and an acid scavenger.

[0021] In an eighth aspect, in any one of the first to seventh aspects, the refrigerating machine oil contains 0.1 wt % or more and 0.5 wt % or less of an antioxidant or an acid scavenger.

[0022] In the eighth aspect, the antioxidant or acid scavenger is contained in an amount of 0.5% by weight or less relative to the weight of the refrigerating machine oil, thereby preventing the dissolution viscosity of the refrigerating machine oil from becoming excessively low due to an increased content of the antioxidant or acid scavenger.

[0023] In a ninth aspect, in any one of the first to eighth aspects, the refrigerating machine oil contains 1.0 wt % or more and 5.0 wt % or less of an extreme pressure additive.

[0024] In the ninth aspect, the content of the extreme pressure additive is 5.0% by weight or less relative to the weight of the refrigerating machine oil, so that the dissolution viscosity of the refrigerating machine oil can be prevented from becoming excessively low due to an increase in the content of the extreme pressure additive.

[0025] In a tenth aspect, in any one of the first to ninth aspects, the molecular weight of the refrigerating machine oil is 1,000 or more and 1,800 or less.

[0026] In the tenth aspect, by setting the molecular weight of the refrigerating machine oil to 1000 or more and 1800 or less, it is possible to suppress dissolution of the hydrocarbon refrigerant into the refrigerating machine oil.

[0027] An eleventh aspect is directed to a refrigeration cycle apparatus. The refrigeration cycle apparatus includes a refrigerant circuit (10) having any one of the first to tenth compressors (20) and circulating a hydrocarbon refrigerant to perform a refrigeration cycle. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a piping diagram of a refrigeration cycle device according to a first embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view of the compressor. [Figure 3] FIG. 3 is an enlarged longitudinal sectional view of a main part of the compressor. [Figure 4] FIG. 4 is a cross-sectional view of the first compression element. [Figure 5] FIG. 5 is a cross-sectional view of the second compression element. [Figure 6]FIG. 6 is a table showing the test conditions for the evaluation test of the amount of wear of the sliding portion. [Figure 7] FIG. 7 is a graph showing the relationship between the amount of wear of the sliding portion and the dissolution viscosity of the refrigerating machine oil. [Figure 8] FIG. 8 is a graph showing the relationship between the solution viscosity of refrigerating machine oil and the loss ratio of the eccentric portion in a plurality of compressors with different displacement volumes. [Figure 9] FIG. 9 is a vertical cross-sectional view of the compressor of the second embodiment. [Figure 10] FIG. 10 is a graph showing the relationship between the solution viscosity of refrigerating machine oil and the bearing loss ratio in a plurality of compressors with different displacement volumes. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. 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.

[0030] <Embodiment 1> (1) Overall structure The refrigeration cycle device of the present disclosure is applied to a stationary air conditioner 1. As shown in Fig. 1, the air conditioner 1 is a pair type having one outdoor unit (OU) installed outdoors and one indoor unit (IU) installed indoors. The outdoor unit (OU) and the indoor unit (IU) are connected to each other via two connecting pipes.

[0031] The air conditioner (1) has a refrigerant circuit (10). The refrigerant circuit (10) is filled with a refrigerant. The refrigerant circuit (10) performs a refrigeration cycle by circulating the refrigerant. The refrigerant circuit (10) has a compressor (20), an outdoor heat exchanger (11), an expansion valve (12), and an indoor heat exchanger (13). The refrigerant circuit (10) further has a four-way switching valve (14) for switching between a cooling cycle and a heating cycle. The compressor (20), the outdoor heat exchanger (11), and the expansion valve (12) are provided in the outdoor unit (OU), and the indoor heat exchanger (13) is provided in the indoor unit (IU). The expansion valve (12) may be provided in the indoor unit (IU).

[0032] The compressor (20) draws in and compresses low-pressure refrigerant from the refrigerant circuit (10). The compressor (20) discharges the compressed refrigerant into the refrigerant circuit (10) as high-pressure refrigerant. The outdoor heat exchanger (11) is a fin-and-tube heat exchanger. The outdoor heat exchanger exchanges heat between the refrigerant in the refrigerant circuit (10) and outdoor air transported by the outdoor fan (15). The expansion valve (12) is an example of a pressure reducing mechanism that reduces the pressure of the refrigerant. The expansion valve (12) is an electronic expansion valve whose opening is adjustable. The indoor heat exchanger (13) is a fin-and-tube heat exchanger. The indoor heat exchanger exchanges heat between the refrigerant in the refrigerant circuit (10) and outdoor air transported by the indoor fan (16).

[0033] The four-way selector valve (14) has a first port (P1), a second port (P2), a third port (P3), and a fourth port (P4). The four-way selector valve (14) switches between a first state indicated by a solid line in FIG. 1 and a second state indicated by a dashed line in FIG. 1. In the first state, the four-way selector valve (14) connects the first port (P1) with the second port (P2) and also connects the third port (P3) with the fourth port (P4). When the four-way selector valve (14) is in the first state, the compressor (20) operates, whereby the outdoor heat exchanger (11) functions as a radiator (condenser) and the indoor heat exchanger (13) functions as an evaporator, thereby performing a cooling cycle. The four-way selector valve (14) in the second state connects the first port (P1) and the third port (P3) and also connects the second port (P2) and the fourth port (P4). When the four-way selector valve (14) is in the second state, the compressor (20) is operated, whereby a heating cycle is performed in which the indoor heat exchanger (13) functions as a radiator (condenser) and the outdoor heat exchanger (11) functions as an evaporator.

[0034] (2) Compressor The configuration of the compressor (20) will be described with reference to Figures 2 to 5. In the following description, the terms "upper" and "lower" refer to the directions indicated by the arrows in Figure 2. In the following description, the term "axial direction" refers to the direction in which the axis (A) of the rotating shaft (30) shown in Figure 2 extends, the term "radial direction" refers to the direction that passes through the axis (A) of the rotating shaft (30) and is perpendicular to the axis (A), and the term "circumferential direction" refers to the direction in which the rotating shaft (30) rotates.

[0035] The compressor (20) is a rotary compressor. The rotary compressor of this embodiment is a so-called swing type in which vanes (53A, 53B) formed integrally with rollers (52A, 52B) swing in association with the eccentric rotation of the rollers (52A, 52B).

[0036] The compressor (20) has a casing (21) and a plurality of components housed in the casing (21). The plurality of components include an electric motor (25), a rotating shaft (30), a rotary compression mechanism (40), bearings (44, 45), and an oil supply mechanism (70). The electric motor (25) is a drive source for the compression mechanism (40). The rotating shaft (30) is connected to the electric motor (25). The bearings (44, 45) rotatably support the rotating shaft (30). The compression mechanism (40) is rotationally driven by the rotating shaft (30) to compress the refrigerant. The oil supply mechanism (70) supplies refrigeration oil, which is a lubricant, to a plurality of sliding parts.

[0037] (2-1) Casing The casing (21) is a hollow, sealed container. In other words, the compressor (20) is a sealed compressor. An internal space (S) is formed inside the casing (21). The casing (21) is formed to be elongated in the axial direction, specifically, in the vertical direction. The casing (21) has a cylindrical body (21a) extending in the vertical direction, an upper lid (21b) closing the upper end of the body (21a), and a lower lid (21c) closing the lower end of the body (21a). The lower lid (21c) forms the bottom of the casing (21).

[0038] The internal space (S) of the casing (21) is filled with refrigerant discharged from the compression mechanism (40). That is, the compressor (20) is of a so-called high-pressure dome type.

[0039] An oil reservoir (35) for storing refrigeration oil is formed at the bottom of the casing (21). In the oil reservoir (35), the oil level of the refrigeration oil changes depending on the operating conditions of the compressor (20) and the air conditioner (1).

[0040] (2-2) First intake pipe, second intake pipe, and discharge pipe A first suction pipe (23A), a second suction pipe (23B), and a discharge pipe (24) are connected to the casing (21). The first suction pipe (23A) and the second suction pipe (23B) extend radially through the body portion (21a). The first suction pipe (23A) and the second suction pipe (23B) are connected to a low-pressure line of the refrigerant circuit (10). The discharge pipe (24) extends axially through the upper lid portion (21b). The discharge pipe (24) is connected to a high-pressure line of the refrigerant circuit (10).

[0041] (2-3) Electric motor The electric motor (25) is located in the upper part of the internal space (S). The electric motor (25) has a stator (26) and a rotor (27). The stator (26) is fixed to the inner peripheral surface of the body portion (21a). The stator (26) is formed in a cylindrical shape when viewed in a cross section perpendicular to the axial direction (horizontal cross section). The rotor (27) is disposed radially inside the stator (26). The rotor (27) is fixed to the outer peripheral surface of the rotating shaft (30). The electric motor (25) is configured so that its rotation speed can be adjusted by an inverter device. In other words, the electric motor (25) is an inverter-type electric motor whose operating frequency is variable.

[0042] (2-4) Rotation axis The rotating shaft (30) is located at the radial center of the internal space (S). The rotating shaft (30) extends vertically. The rotating shaft (30) has a shaft body (31) and a first eccentric portion (32A) and a second eccentric portion (32B), each of which is radially eccentric from an axial center (A) of the shaft body (31). The rotor (27) of the electric motor (25) is connected to an upper portion of the shaft body (31). The first eccentric portion (32A) and the second eccentric portion (32B) are formed in a lower portion of the shaft body (31). The first eccentric portion (32A) is located above the second eccentric portion (32B). The direction in which the first eccentric portion (32A) is eccentric from the axial center (A) and the direction in which the second eccentric portion (32B) is eccentric from the axial center are circumferentially offset by 180° from each other.

[0043] (2-5) Overall configuration of the compression mechanism The compression mechanism (40) is disposed below the electric motor (25). The compression mechanism (40) includes, in order from top to bottom, a front head (41), a first cylinder (51A), a middle plate (42), a second cylinder (51B), and a rear head (43). These members are fixed to each other by bolts extending in the axial direction.

[0044] The compression mechanism (40) of this embodiment includes a first compression element (C1) and a second compression element (C2). The first compression element (C1) includes a first roller (52A) and a first vane (53A). The second compression element (C2) includes a second roller (52B) and a second vane (53B). In the compression mechanism (40) of this embodiment, the rollers (52A, 52B) and the vanes (53A, 53B) are integrally formed, and the vanes (53A, 53B) swing in accordance with the eccentric rotation of the rollers (52A, 52B).

[0045] A first cylinder chamber (54A) is formed inside the first cylinder (51A). The first cylinder chamber (54A) passes through the first cylinder (51A) in the axial direction. A second cylinder chamber (54B) is formed inside the second cylinder (51B). The second cylinder chamber (54B) passes through the second cylinder (51B) in the axial direction.

[0046] (2-5-1) Closure member The front head (41), the middle plate (42), and the rear head (43) are examples of closing members that close the cylinder chambers (54A, 54B) in the axial direction. The front head (41) has a first closing portion (41a) that is a flat plate and has a slight thickness in the axial direction, and an upper bearing portion (41b) that extends upward from the radial center of the first closing portion (41a).

[0047] The lower surface of the first closing portion (41a) closes the upper opening of the first cylinder chamber (54A). As shown in Fig. 4, the first closing portion (41a) is formed with a first discharge port (55A) that communicates with the high-pressure chamber (compression chamber) of the first cylinder chamber (54A). The first discharge port (55A) is opened and closed by a first discharge valve (not shown).

[0048] The upper bearing portion (41b) is formed in a cylindrical shape extending in the axial direction along the rotating shaft (30). The rotating shaft (30) passes through the upper bearing portion (41b). A first bearing (44) is formed on the inner peripheral surface of the upper bearing portion (41b). The first bearing (44) rotatably supports the main shaft portion of the rotating shaft (30). The first bearing (44) is a sliding bearing, specifically a journal bearing.

[0049] The middle plate (42) is disposed between the first cylinder (51A) and the second cylinder (51B). The middle plate (42) is formed in an annular shape. The rotary shaft (30) passes through the middle plate (42). The upper surface of the middle plate (42) closes the lower opening of the first cylinder chamber (54A). The lower surface of the middle plate (42) closes the upper opening of the second cylinder chamber (54B).

[0050] The rear head (43) has a second closing portion (43a) that is a flat plate and slightly thick in the axial direction, and a lower bearing portion (43b) that extends downward from the radial center of the second closing portion (43a). The upper surface of the second closing portion (43a) closes the lower opening of the second cylinder chamber (54B). As shown in FIG. 5, the second closing portion (43a) has a second discharge port (55B) that communicates with the high-pressure chamber (compression chamber) of the second cylinder chamber (54B). The second discharge port (55B) is opened and closed by a second discharge valve (not shown).

[0051] The lower bearing portion (43b) is formed in a cylindrical shape extending in the axial direction along the rotating shaft (30). The rotating shaft (30) passes through the lower bearing portion (43b). A second bearing (45) is formed on the inner peripheral surface of the lower bearing portion (43b). The second bearing (45) rotatably supports the countershaft portion of the rotating shaft (30). The second bearing (45) is a sliding bearing, specifically a journal bearing.

[0052] (2-5-2) Details of the first compression element The first compression element (C1) shown in FIG. 4 includes a first eccentric part (32A), a first cylinder (51A), a first roller (52A), a first vane (53A), and a pair of first bushings (56A).

[0053] The first cylinder (51A) is an annular member having a slight thickness in the axial direction. A first cylinder chamber (54A) is formed inside the first cylinder (51A). The first cylinder chamber (54A) is formed in a circular shape when viewed in the axial direction. A first suction passage (57A) and a first bushing groove (58A) are formed in the first cylinder (51A). The first suction passage (57A) passes through the first cylinder (51A) in the radial direction. The first suction passage (57A) communicates with the first suction pipe (23A).

[0054] The first roller (52A) is disposed in the first cylinder chamber (54A). The first roller (52A) is formed in an annular shape when viewed in the axial direction. The first eccentric portion (32A) is fitted inside the first roller (52A). The inner peripheral surface of the first roller (52A) and the outer peripheral surface of the first eccentric portion (32A) slide relative to each other. The first eccentric portion (32A) causes the first roller (52A) to eccentrically rotate. The first roller (52A) eccentrically rotates along the inner peripheral surface of the first cylinder chamber (54A) while forming a seal between itself and the inner peripheral surface of the first cylinder chamber (54A).

[0055] The first bushing groove (58A) is formed on the top dead center side (upper side in FIG. 3 ) of the first cylinder (51A). The first bushing groove (58A) is formed in a circular shape when viewed in the axial direction. The pair of first bushings (56A) are fitted into the first bushing groove (58A). Each of the pair of first bushings (56A) has an arc portion shaped along the inner surface of the first bushing groove (58A) and flat portions continuous with both ends of the arc portion. The pair of first bushings (56A) are arranged in the first bushing groove (58A) such that the flat portions face each other. The flat portions of the pair of first bushings (56A) hold the first vane (53A). The pair of first bushings (56A) are configured to be swingable along the inner surface of the first bushing groove (58A). The first vane (53A) is configured to be able to move reciprocally in the radial direction between the pair of first bushings (56A).

[0056] The first vane (53A) constitutes a partition member that divides the first cylinder chamber (54A) into a low-pressure chamber (L) and a high-pressure chamber (H). A radially inner portion of the first vane (53A) is continuous with the outer peripheral surface of the first roller (52A). The low-pressure chamber (L) of the first cylinder chamber (54A) communicates with the first suction passage (57A) and constitutes a suction chamber into which low-pressure refrigerant flows. The high-pressure chamber (H) of the first cylinder chamber (54A) is isolated from the first suction passage (57A) and constitutes a compression chamber for compressing the refrigerant.

[0057] (2-5-3) Details of the second compression element The second compression element (C2) shown in Fig. 5 includes a second eccentric portion (32B), a second cylinder (51B), a second roller (52B), a second vane (53B), and a pair of second bushings (56B). The basic structures of the second eccentric portion (32B), the second cylinder (51B), the second roller (52B), the second vane (53B), and the pair of second bushings (56B) are the same as those of the first eccentric portion (32A), the first cylinder (51A), the first roller (52A), the first vane (53A), and the pair of first bushings (56A), respectively, and therefore detailed description thereof will be omitted. The second cylinder (51B) is formed with a second cylinder chamber (54B), a second suction passage (57B), and a second bushing groove (58B). The second cylinder chamber (54B), the second suction passage (57B), and the second bush groove (58B) have the same basic structures as the first cylinder chamber (54A), the first suction passage (57A), and the first bush groove (58A), respectively, and therefore detailed description thereof will be omitted. The second suction passage (57B) is in communication with the second suction pipe (23B). The first roller (52A) and the second roller (52B) are out of phase with each other by 180° during eccentric rotation.

[0058] (2-6) Oil supply mechanism The oil supply mechanism (70) shown in Fig. 3 supplies refrigeration oil from the oil reservoir (35) to a plurality of sliding parts. The oil supply mechanism (70) is provided below the rotating shaft (30). The oil supply mechanism (70) includes an oil supply pump (71) and an oil supply passage (72).

[0059] The oil supply pump (71) is provided at the lower end of the rotary shaft (30). The oil supply pump (71) is located at a position lower than the oil level in the oil reservoir (35). The oil supply pump (71) transports refrigeration oil from the oil reservoir (35). The oil supply pump (71) has a suction port (71a) that draws the refrigeration oil from the oil reservoir (35). The suction port (71a) opens downward toward the bottom of the casing (21). The oil supply pump (71) is a differential pressure type, centrifugal type, or positive displacement type pump.

[0060] The oil supply passage (72) is formed inside the rotary shaft (30). The oil supply passage (72) is in communication with the discharge side of the oil supply pump (71). The oil supply passage (72) has a main flow path (73) extending vertically so as to pass through the axis of the rotary shaft (30) and a plurality of branch flow paths extending radially from the main flow path (73). The plurality of branch flow paths include, in order from top to bottom, a first branch flow path (74a), a second branch flow path (74b), a third branch flow path (74c), and a fourth branch flow path (74d).

[0061] The first branch channel (74a) is located at the same height as the upper bearing portion (41b). An outlet of the first branch channel (74a) opens toward the first bearing (44). In other words, the first branch channel (74a) opens toward the sliding portion between the first bearing (44) and the rotary shaft (30). The second branch channel (74b) is formed in the first eccentric portion (32A). An outlet of the second branch channel (74b) opens toward the inner circumferential surface of the first roller (52A). In other words, the second branch channel (74b) opens toward the sliding portion between the first roller (52A) and the first eccentric portion (32A). The third branch channel (74c) is formed in the second eccentric portion (32B). An outlet of the third branch channel (74c) opens toward the inner circumferential surface of the first roller (52A). In other words, the third branch channel (74c) opens toward the sliding portion between the second roller (52B) and the second eccentric portion (32B). The fourth branch channel (74d) is located at the same height as the lower bearing portion (43b). The outlet of the fourth branch channel (74d) opens toward the second bearing (45). In other words, the fourth branch channel (74d) opens toward the sliding portion between the second bearing (45) and the rotating shaft (30).

[0062] (2-7) Driving behavior When the rotary shaft (30) is driven to rotate by the electric motor (25), the first eccentric portion (32A) and the second eccentric portion (32B) rotate eccentrically. In the first compression element (C1), low-pressure refrigerant is sucked from the first suction pipe (23A) into the low-pressure chamber (L) of the first cylinder chamber (54A) in accordance with the eccentric rotation of the first roller (52A). At the same time, the refrigerant is compressed in the high-pressure chamber (H) of the first cylinder chamber (54A). In the second compression element (C2), low-pressure refrigerant is sucked from the second suction pipe (23B) into the low-pressure chamber (L) of the first cylinder chamber (54A) in accordance with the eccentric rotation of the second roller (52B). At the same time, the refrigerant is compressed in the high-pressure chamber of the second cylinder chamber (54B).

[0063] When the internal pressure of the compression chamber of the first compression element (C1) increases and the first reed valve opens, high-pressure refrigerant is discharged into the internal space (S) through the first discharge port (55A). When the internal pressure of the compression chamber of the second compression element (C2) increases and the second reed valve opens, high-pressure refrigerant is discharged into the internal space (S) through the second discharge port (55B). The high-pressure refrigerant around the compression mechanism (40) passes upward through the electric motor (25) and is discharged into the refrigerant circuit (10) through the discharge pipe (24).

[0064] When the rotating shaft (30) rotates, the oil supply pump (71) rotates together with the rotating shaft (30). As a result, refrigeration oil in the oil reservoir (35) is sucked into the suction port (71a). The oil supply pump (71) delivers the refrigeration oil sucked through the suction port (71a) to the branch flow paths (71a, 71b, 71c, 71d) through the main flow path (73). The refrigeration oil in the first branch flow path (74a) is used to lubricate the sliding parts of the first bearing (44), the refrigeration oil in the second branch flow path (74b) is used to lubricate the sliding parts of the first eccentric portion (32A), the refrigeration oil in the third branch flow path (74c) is used to lubricate the sliding parts of the second eccentric portion (32B), and the refrigeration oil in the fourth branch flow path (74d) is used to lubricate the sliding parts of the second bearing (45).

[0065] (3) Refrigerant The refrigerant in this embodiment is a hydrocarbon refrigerant. The hydrocarbon refrigerant in this embodiment is a single refrigerant made of propane (R290). Propane has an extremely low global warming potential and is environmentally friendly. On the other hand, hydrocarbon refrigerants such as propane have a molecular structure similar to that of refrigerating machine oil, and therefore have the property of easily dissolving in refrigerating machine oil.

[0066] The hydrocarbon refrigerant may be a single refrigerant consisting of isobutane. The refrigerant in the refrigerant circuit (10) may be a mixed refrigerant containing a hydrocarbon refrigerant and at least one other refrigerant. Examples of other refrigerants that may be used include HFC (hydrofluorocarbon) refrigerants, HFO (hydrofluoroolefin) refrigerants, and CF3I (trifluoroiodomethane).

[0067] (4) Refrigerating machine oil Next, a description will be given of the refrigerating machine oil used in the refrigerant circuit 10. The refrigerating machine oil here refers to a fluid containing additives such as an extreme-pressure additive, an antioxidant, and an acid scavenger in addition to components (lubricating oil) used to lubricate sliding parts.

[0068] (4-1) Components and characteristics of refrigeration oil The refrigerating machine oil used in the refrigerant circuit (10) of the present embodiment contains any one of PAG (polyalkylene glycol), PVE (polyvinyl ether), and POE (polyol ester). The refrigerating machine oil mainly contains PAG, PVE, or POE.

[0069] Hydrocarbon refrigerants such as propane have a molecular structure similar to that of refrigerating machine oil, making them easily soluble in refrigerating machine oil. In contrast, PAG, PVE, or POE have relatively low compatibility with hydrocarbon refrigerants. Therefore, using PAG, PVE, or POE as the refrigerating machine oil can prevent the refrigerant from dissolving in the refrigerating machine oil. Refrigerating machine oil can also be alkylbenzene or mineral oil.

[0070] Refrigeration oil has the property of separating into two layers when the refrigerant pressure is 1.9 MPa and the temperature of the refrigeration oil is 75° C. Therefore, the refrigeration oil in the oil reservoir (35) separates into two layers when the refrigerant pressure in the casing (21) is 1.9 MPa and the temperature of the refrigeration oil is 75° C.

[0071] Generally, refrigeration oil dissolves uniformly in refrigerant. However, if refrigeration oil with low solubility in refrigerant is used, a concentration gradient between the refrigeration oil and the refrigerant occurs in the oil reservoir (35), resulting in the refrigeration oil being in a so-called two-layer separation state. The refrigeration oil near the oil surface in the oil reservoir (35) has a low refrigerant density and therefore forms a layer with high refrigerant solubility. The refrigeration oil near the bottom of the oil reservoir (35) has a high refrigerant density and therefore forms a layer with low refrigerant solubility. The solution viscosity of the refrigeration oil changes depending on the refrigerant solubility. Therefore, by suppressing the refrigerant solubility, the solution viscosity of the refrigeration oil can be ensured. When the refrigerant and refrigeration oil are mixed, the refrigerant and refrigeration oil do not dissolve and are separated into two layers, or an emulsion state is called a two-layer separation state.

[0072] The molecular weight of the refrigerating machine oil is preferably 1,000 or more and 1,800 or less.

[0073] The refrigerating machine oil contains at least one additive selected from the group consisting of a phosphate ester extreme pressure additive, an antioxidant, and an acid scavenger.

[0074] As the phosphate extreme pressure additive, those containing phosphate ester, phosphite ester, acid phosphate ester, acid phosphite ester, and amine salt of acid phosphite ester can be used.

[0075] The acid scavenger may be an epoxy compound such as phenyl glycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, α-olefin oxide, or epoxidized soybean oil.

[0076] As the antioxidant, a phenol-based antioxidant or an amine-based antioxidant can be used.

[0077] The refrigerating machine oil contains 1.0 wt % or more and 5.0 wt % or less of an extreme pressure additive. The refrigerating machine oil contains 0.1 wt % or more and 0.5 wt % or less of an antioxidant or an acid scavenger.

[0078] The refrigerating machine oil of this embodiment has a surface tension of 0.25 [N / m] or more and 0.40 [N / m] or less at 20° C. The surface tension of the refrigerating machine oil is measured by a method in accordance with JIS K2241.

[0079] (4-2) Dissolution viscosity of refrigerating machine oil in the oil reservoir The melt viscosity of the refrigeration oil in the oil reservoir (35) of the casing (21) of the compressor (20) will be described in detail. Refrigeration oil located in the oil reservoir (35) at a height position h1 or lower of the suction port (71a) of the oil supply pump (71) is defined as a first refrigeration oil. The height position h1 of the suction port (71a) refers to the absolute height of a horizontal plane passing through the suction port (71a). In this embodiment, the melt viscosity η of the first refrigeration oil is equal to or higher than the first melt viscosity η1 and equal to or lower than the second melt viscosity η2. In other words, the refrigeration oil is configured so that the melt viscosity η of the first refrigeration oil in the oil reservoir (35) is in the range of equal to or higher than η1 and equal to or lower than η2. Here, the "melt viscosity" refers to the viscosity of a fluid in which a refrigerant is dissolved in the refrigeration oil. The viscosity of this fluid is measured by a method conforming to JIS K2283. The melt viscosity of the refrigeration oil varies depending on the content of the extreme-pressure additive, antioxidant, or oxygen scavenger.

[0080] The temperature and pressure conditions of the oil reservoir (35) vary depending on the operating conditions of the compressor (20) and the refrigerant circuit (10). The temperature ranges from 72 to 80°C, and the pressure ranges from 1.9 MPa. Therefore, under these operating conditions, the refrigeration oil is configured so that the melt viscosity η of the first refrigeration oil at 72 to 80°C and 1.9 MPa is equal to or greater than the first melt viscosity η1 and equal to or less than the second melt viscosity η2. The melt viscosity under these operating conditions can be measured, for example, by a viscometer attached to the casing (21). The viscometer is attached to the body (21a) or the lower cover (21c) of the casing (21). The melt viscosity of the first refrigeration oil in the oil reservoir (35), which is equal to or less than h1, can be measured by the viscometer.

[0081] (4-2-1) Lower limit of solution viscosity The first soluble viscosity η1, which is the lower limit of the soluble viscosity of the first refrigeration oil, is 5.0 mPa·s. In other words, the soluble viscosity η of the first refrigeration oil is 5.0 mPa·s or more. This reduces the amount of wear of each sliding part, such as the first bearing (44), the second bearing (45), the first eccentric portion (32A), and the second eccentric portion (32B). Test results verifying the relationship between the amount of wear of the sliding parts and the soluble viscosity of the refrigeration oil will be described with reference to FIGS. 6 and 7.

[0082] Figure 6 shows the test conditions. The wear amount of the sliding parts was evaluated by the FALEX test specified in ASTM standard D3233-19. In the FALEX test, cast iron (FC250), which corresponds to the material of the sliding parts of the compressor (20), was used as the test piece (pin). A hydrocarbon refrigerant (propane) was dissolved in refrigeration oil, and several refrigeration oils with different dissolution viscosities were prepared. For each refrigeration oil, the test piece (pin) lubricated with the refrigeration oil was sandwiched between two blocks and rotated for 60 minutes under a predetermined load (150 lbs), and the wear amount was measured. The ambient temperature of the test piece was 80°C, which corresponds to the temperature inside the casing (21) in a normal refrigeration cycle.

[0083] FIG. 7 shows the relationship between the solution viscosity of refrigeration oil and the amount of wear of a test piece, measured by a FALEX test. The test results showed that there was no wear of the test piece when the solution viscosity was in the range of 6 mPa·s to 10 mPa·s. It was confirmed that wear occurred on the test piece when the solution viscosity was lower than 6 mPa·s, and that the amount of wear increased sharply when the solution viscosity was lower than 5 mPa·s. When the solution viscosity was 5 mPa·s or higher, the amount of wear could be suppressed to 1 mg or less. Therefore, in order to suppress wear of the sliding parts, it is recommended that the solution viscosity be 5.0 mPa·s or higher. In the compressor (20) of this embodiment, the use of a refrigeration oil with a solution viscosity of 5.0 mPa·s or higher can also appropriately suppress wear of the sliding parts.

[0084] In this embodiment, the first refrigeration oil at a height position h1 or lower of the suction port (71a) has a melt viscosity η of 5.0 mPa·s or higher. Therefore, the oil supply mechanism (70) can supply refrigeration oil having a melt viscosity of 5.0 mPa·s or higher to the sliding parts of the first bearing (44), the second bearing (45), the first eccentric portion (32A), and the second eccentric portion (32B). As a result, wear at each sliding part can be suppressed.

[0085] (4-2-2) Upper limit of solution viscosity The following describes the results of examining the second soluble viscosity η2, which is the upper limit of the soluble viscosity of the first refrigeration oil. Figure 8 shows the results of examining the relationship between the soluble viscosity of the refrigeration oil, the displacement volume Vc of the compression mechanism, and the loss ratio γ of the eccentric section. Line L1 in Figure 8 represents a compressor with a displacement volume Vc of 17.2 cc, line L2 represents a compressor with a displacement volume Vc of 25.9 cc, and line L3 represents a compressor with a displacement volume Vc of 35.0 cc. Figure 8 shows the relationship between the soluble viscosity of the refrigeration oil and the loss ratio γ of the eccentric section for three compressors with different displacement volumes Vc.

[0086] Displacement volume Vc is the volume of the high-pressure chamber (compression chamber) when the low-pressure chamber is completely closed within the cylinder to form the high-pressure chamber (compression chamber), and corresponds to the maximum volume of the compression chamber. If the compression mechanism is a two-cylinder type, Vc defined here is the sum of the displacement volume Vc-1 of the first cylinder and the displacement volume Vc-2 of the second cylinder. If the number of cylinders is n and the displacement volumes of each cylinder are Vc-n, Vc-n+1, ​​..., then displacement volume Vc is the sum of these displacement volumes Vc-n, Vc-n+1, ​​...

[0087] The loss ratio γ of the eccentric part is the ratio [%] of the sliding loss [W] of the eccentric part to the input [W] of the compressor. The sliding loss of the eccentric part is the sum of the sliding losses of the two eccentric parts in the case of a two-cylinder type, and if the number of cylinders is n, it is the sum of the sliding losses of n eccentric parts (32A, 32B).

[0088] As can be seen from Figure 8, as the displacement volume Vc increases, the loss ratio γ of the eccentric portion increases. As the displacement volume Vc of the compression mechanism increases, the size of the eccentric portion increases, and the projected area of ​​the eccentric portion when viewed from the radially outside increases. When the eccentric portion rotates eccentrically, a load acts from the eccentric portion on the roller in the area corresponding to this projected area, and this load has a significant effect on the sliding loss [W]. Therefore, as the displacement volume Vc increases, the projected area also increases, and the sliding loss and, in turn, the loss ratio γ of the eccentric portion increase.

[0089] As can be seen from Figure 8, the loss ratio γ of the eccentric portion increases as the solution viscosity of the refrigeration oil increases. This is because the sliding loss of the eccentric portion increases as the solution viscosity of the refrigeration oil increases.

[0090] Taking the above points into consideration, based on the displacement volume Vc, the soluble viscosity of the refrigeration oil, and the loss ratio γ of the eccentric part shown in Figure 8, we obtained the relational expression (1) for the upper limit of the soluble viscosity (second soluble viscosity η2) to keep the loss ratio γ of the eccentric part at 10% or less.

[0091] η2=(-0.00101×Vc+0.12286) / (0.0000146×Vc+0.00505) Equation (1) Here, Vc in the relational expression (1) is the displacement volume [cc] of the above-mentioned compression mechanism (40). By setting the solution viscosity of the refrigeration oil to η2 or less, the loss ratio γ of the eccentric portion can be set to 10% or less.

[0092] In the present embodiment, the solution viscosity η of the first refrigeration oil is equal to or less than (−0.00101×Vc+0.12286) / (0.0000146×Vc+0.00505). Therefore, in the present embodiment, the sliding loss of the eccentric parts (32A, 32B) of the compression mechanism (40) can be reduced to 10% or less of the input power of the compressor (20). Here, the sliding loss of the eccentric parts (32A, 32B) accounts for a large proportion of the overall mechanical loss of the compressor (20). Therefore, by setting the loss ratio γ to 10% or less, it is possible to effectively prevent a decrease in the efficiency of the compressor (20).

[0093] In addition, since a relatively large amount of refrigeration oil is supplied to the sliding portions of the eccentric portions (32A, 32B), a fluid lubrication region is formed between the eccentric portions (32A, 32B) and the rollers (52A, 52B). Therefore, the sliding loss of the eccentric portions (32A, 32B) is easily affected by the solution viscosity of the refrigeration oil. Therefore, by setting the solution viscosity of the refrigeration oil to be equal to or less than the upper limit of the above relational expression (1), an increase in the sliding loss of the eccentric portions (32A, 32B) can be effectively suppressed.

[0094] (4-3) First Refrigerant Oil As described above, the first refrigeration oil is refrigeration oil present in the oil reservoir (35) at a height below the suction port (71a). However, the first refrigeration oil is preferably refrigeration oil present below the suction port (71a), near the suction port (71a), or inside the suction port (71a). By setting the melt viscosity η of such refrigeration oil to η1 or more, wear of the sliding parts in particular can be suppressed. By setting the melt viscosity η of such refrigeration oil to η2 or less, sliding loss of the eccentric parts (32A, 32B) in particular can be reduced.

[0095] (5) Effects of the First Embodiment (5-1) The refrigerant in this embodiment is a hydrocarbon refrigerant. The hydrocarbon refrigerant in this embodiment is a single refrigerant, propane. Propane has an extremely low global warming potential and is environmentally friendly. On the other hand, hydrocarbon refrigerants such as propane have a molecular structure similar to that of refrigerating machine oil and therefore are easily soluble in refrigerating machine oil. Therefore, excessive dissolution of the refrigerant in refrigerating machine oil may reduce the solution viscosity of the refrigerating machine oil. If the solution viscosity of the refrigerating machine oil decreases, the viscosity of the refrigerating machine oil supplied to the sliding parts of the first bearing (44), the second bearing (45), the first eccentric portion (32A), and the second eccentric portion (32B) also decreases, which may result in poor lubrication of these sliding parts.

[0096] In this embodiment, the first refrigeration oil present in the oil reservoir (35) at a height below the suction port (71a) has a solution viscosity η of 5.0 mPa·S or more.

[0097] This allows refrigeration oil having a solution viscosity of 5.0 mPa·S or more to be supplied to the sliding parts of the bearings (44, 45) and the sliding parts of the eccentric parts (32A, 32B), thereby suppressing wear of these sliding parts and improving the reliability and life of the compressor (20).

[0098] (5-2) The solution viscosity η of the first refrigeration oil is equal to or less than (−0.00101×Vc+0.12286) / (0.0000146×Vc+0.00505).

[0099] This reduces the friction loss at the eccentric portions (32A, 32B). Specifically, the friction loss at the eccentric portions (32A, 32B) can be reduced to 10% or less of the input power of the compressor (20). This reduces the mechanical loss of the compressor (20), improves the efficiency of the compressor (20), and further improves the COP (coefficient of performance) of the refrigerant circuit (10).

[0100] (5-3) The refrigeration oil contains either a polyalkylene glycol, a polyvinyl ether, or a polyol ester.

[0101] By using such refrigeration oils, the hydrocarbon refrigerant is less likely to dissolve in the refrigeration oil. If the hydrocarbon refrigerant dissolves in the refrigeration oil, the solution viscosity of the first refrigeration oil decreases. In contrast, by using such refrigeration oils, the solution viscosity of the first refrigeration oil can be prevented from becoming excessively low.

[0102] In particular, by setting the molecular weight of the refrigerating machine oil to 1000 or more and 1800 or less, it is possible to effectively prevent the hydrocarbon refrigerant from dissolving in the refrigerating machine oil.

[0103] Because hydrocarbon refrigerants are highly flammable, the amount of refrigerant charged into the refrigerant circuit (10) may be limited. Therefore, if an excessive amount of hydrocarbon refrigerant dissolves in the refrigeration oil, the amount of refrigerant used in the refrigeration cycle may not be sufficient. In contrast, by suppressing the dissolution of hydrocarbon refrigerant into the refrigeration oil in this manner, the amount of refrigerant used in the refrigeration cycle can be ensured.

[0104] (5-4) The refrigerating machine oil contains at least one of a phosphate ester extreme pressure additive, an antioxidant, and an acid scavenger.

[0105] When the refrigeration oil contains an antioxidant, the refrigeration oil contains 0.1 wt. % or more and 0.5 wt. % or less of the antioxidant. Hydrocarbon refrigerants have a chemically stable structure and are less likely to decompose during the refrigeration cycle than HFC refrigerants or HFO refrigerants. Therefore, even if the amount of antioxidant is 0.5 wt. % or less, the refrigerant can be used stably for a long period of time. Furthermore, limiting the amount of antioxidant to 0.5 wt. % or less prevents the viscosity of the refrigeration oil from decreasing. As a result, the dissolution viscosity η of the first refrigeration oil is more likely to be 5.0 mPa·S or more, thereby suppressing wear of the sliding parts. In this way, by preventing the hydrocarbon refrigerant from dissolving in the refrigeration oil, the amount of refrigerant used in the refrigeration cycle can be secured.

[0106] When the refrigerating machine oil contains an acid scavenger, the refrigerating machine oil contains 0.1 wt. % or more and 0.5 wt. % or less of the acid scavenger. As described above, hydrocarbon refrigerants have a chemically stable structure and are less likely to decompose during the refrigeration cycle than HFC refrigerants or HFO refrigerants. Therefore, even if the amount of acid scavenger is 0.5 wt. % or less, the refrigerant can be used stably for a long period of time. Furthermore, limiting the amount of acid scavenger to 0.5 wt. % or less prevents the viscosity of the refrigerating machine oil from decreasing. As a result, the dissolution viscosity η of the first refrigerating machine oil is more likely to be 5.0 mPa·S or more, thereby suppressing wear of the sliding parts. In this way, by preventing the hydrocarbon refrigerant from dissolving in the refrigerating machine oil, the amount of refrigerant used in the refrigeration cycle can be secured.

[0107] When the refrigeration oil contains an extreme-pressure additive, the refrigeration oil contains 1.0 wt. % or more and 5.0 wt. % or less of the extreme-pressure additive. By limiting the amount of extreme-pressure additive to 5.0 wt. % or less, a decrease in the viscosity of the refrigeration oil can be prevented. As a result, the solution viscosity η of the first refrigeration oil can be easily maintained at 5.0 mPa·S or more, which can reduce wear on the sliding parts. In this way, by preventing hydrocarbon refrigerants from dissolving in the refrigeration oil, the amount of refrigerant used in the refrigeration cycle can be secured.

[0108] <Embodiment 2> The compressor of the second embodiment is a scroll compressor (120).

[0109] (6-1) Overall structure As shown in FIG. 9 , the scroll compressor (hereinafter also referred to as the compressor (120)) has a casing (121) and a plurality of components housed in the casing (121). The plurality of components include an electric motor (125), a rotating shaft (130), a scroll-type compression mechanism (140), bearings (152, 156, 157), and an oil supply mechanism (170). The electric motor (125) is a drive source for the compression mechanism (140). The rotating shaft (130) is connected to the electric motor (125). The bearings (152, 156, 157) rotatably support the rotating shaft (130). The compression mechanism (140) is rotationally driven by the rotating shaft (130) to compress the refrigerant. The oil supply mechanism (170) supplies refrigeration oil, which is a lubricant, to a plurality of sliding parts.

[0110] The casing (121) is a hollow, sealed container. In other words, the compressor (120) is a sealed compressor. An internal space (S) is formed inside the casing (121). The casing (121) is elongated in the axial direction, specifically, in the vertical direction. The casing (121) has a cylindrical body (121a) extending in the vertical direction, an upper head (121b) closing the upper end of the body (121a), and a lower head (121c) closing the lower end of the body (21a). The lower head (121c) forms the bottom of the casing (21).

[0111] The internal space (S) of the casing (121) is filled with refrigerant discharged from the compression mechanism (140). That is, the compressor (120) is of a so-called high-pressure dome type. The internal space (S) includes a first space (S1) above the compression mechanism (140) and a second space (S2) below the compression mechanism (140).

[0112] An oil reservoir (135) for storing refrigeration oil is formed at the bottom of the casing (121). In the oil reservoir (135), the oil level of the refrigeration oil changes depending on the operating conditions of the compressor (120) and the air conditioner (1).

[0113] A suction pipe (123) and a discharge pipe (124) are connected to the casing (121). The suction pipe (123) passes through the upper head (121b) in the axial direction. The outlet end of the suction pipe (123) is connected to the suction side of the compression mechanism (140). The discharge pipe (124) passes through the body (121a) in the radial direction. The discharge pipe (124) communicates with an internal space (S) filled with high-pressure refrigerant.

[0114] The electric motor (125) is located in the lower part of the internal space (S). The electric motor (125) includes a stator (126) and a rotor (127). The stator (126) is fixed to the inner circumferential surface of the body (121a). The rotor (127) is fixed to the outer circumferential surface of the rotary shaft (130). The electric motor (125) is configured so that its rotation speed can be adjusted by an inverter device. In other words, the electric motor (125) is an inverter-type electric motor whose operating frequency is variable.

[0115] The rotating shaft (130) is located at the radial center of the internal space (S). The rotating shaft (130) extends vertically. The rotating shaft (130) has a shaft body (131) and an upper eccentric portion (132) that is radially eccentric from the axis of the shaft body (131). The rotor (127) of the electric motor (125) is connected to the shaft body (131). The upper eccentric portion (132) is formed at the upper end of the shaft body (131).

[0116] A housing (150) is provided inside the casing (121). The housing (150) is located above the electric motor (125) and is fixed to the inner surface of the body (121a). A recess (151) is formed in the upper surface of the housing (150). An upper bearing (152) is provided in the center of the lower part of the recess (151). The upper bearing (152) rotatably supports the upper part of the shaft body (131). A crank chamber (153) is formed inside the recess (151) in which the upper eccentric part (132) is movable.

[0117] A lower bearing member (155) is provided inside the casing (121). The lower bearing member (155) is fixed to the lower part of the inner surface of the body part (121a). A lower bearing (156) is provided in the center of the lower bearing member (155). The lower bearing (156) rotatably supports the lower part of the shaft body (131).

[0118] The compression mechanism (140) includes a fixed scroll (141) and a movable scroll (160). The fixed scroll (141) is fixed to an upper surface of the housing (150). The movable scroll (160) is disposed between the fixed scroll (141) and the housing (150). A compression chamber (C) is formed between the fixed scroll (141) and the movable scroll (160).

[0119] The fixed scroll (141) has a fixed end plate (142), a fixed wrap (143), and an outer peripheral wall (144). The fixed end plate (142) is formed at the upper end of the fixed scroll (141). The fixed wrap (143) protrudes downward from the fixed end plate (142). The fixed end plate (142) is formed in a spiral shape when viewed in axial cross section. The outer peripheral wall (144) is formed on the outer peripheral edge of the fixed scroll (141) so as to surround the fixed end plate (142). The outer peripheral wall (144) is formed with an intake port (146) that communicates with the intake pipe (123). A discharge port (147) that communicates with the internal space (S) is formed in the center of the fixed end plate (142).

[0120] The movable scroll (160) has a movable end plate (161), a movable lap (162), and a boss (163). The movable end plate (161) is located above the upper eccentric portion (132). The movable lap (162) protrudes upward from the movable end plate (161). The fixed end plate (142) is formed in a spiral shape in an axial cross section. The boss (163) protrudes downward from the center of the movable end plate. The upper eccentric portion (132) is fitted into the boss (163). Strictly speaking, a pin bearing (157) is provided between the inner surface of the boss (163) and the upper eccentric portion (132).

[0121] (6-2) Fueling mechanism The oil supply mechanism (170) supplies refrigeration oil from the oil reservoir (135) to a plurality of sliding parts. The oil supply mechanism (170) is provided below the rotating shaft (130). The oil supply mechanism (170) includes an oil supply pump (171) and an oil supply passage (172).

[0122] The oil supply pump (171) is provided at the lower end of the rotating shaft (130). The oil supply pump (171) is located at a position lower than the oil level in the oil reservoir (135). The oil supply pump (171) transports refrigeration oil from the oil reservoir (135). The oil supply pump (171) has a suction port (171a) through which the refrigeration oil from the oil reservoir (135) is drawn. The suction port (171a) opens downward toward the bottom of the casing (121). The oil supply pump (171) is a differential pressure type, centrifugal type, or positive displacement type pump.

[0123] The oil supply passage (172) is in communication with the discharge side of the oil supply pump (171). The oil supply passage (172) has a main flow path (173) extending axially inside the rotary shaft (130) and a plurality of branch flow paths (174a, 174b, 174c) extending radially from the main flow path (173). The plurality of branch flow paths include, in order from bottom to top, a fifth branch flow path (174a), a sixth branch flow path (174b), and a seventh branch flow path (174c).

[0124] The fifth branch flow path (174a) is located at the same height as the lower bearing (156). The outlet of the fifth branch flow path (174a) opens toward the lower bearing (156). In other words, the fifth branch flow path (174a) opens toward the sliding portion between the lower bearing (156) and the rotating shaft (130). The sixth branch flow path (174b) is located at the same height as the upper bearing (152). The outlet of the sixth branch flow path (174b) opens toward the upper bearing (152). In other words, the sixth branch flow path (174b) opens toward the sliding portion between the upper bearing (152) and the rotating shaft (130). The seventh branch flow path (174c) is located at the same height as the pin bearing (157). The outlet of the seventh branch flow path (174c) opens toward the pin bearing (157). In other words, the seventh branch channel (174c) opens toward the sliding portion between the pin bearing (157) and the upper eccentric portion (132).

[0125] The oil supply mechanism (170) of the second embodiment includes an oil introduction passage (175) for introducing refrigeration oil into the compression mechanism (140). The oil introduction passage (175) includes an oil groove (176), a housing-side flow path (177), and a fixed-side flow path (178). The oil groove (176) is an annular groove formed around the upper bearing (152). Refrigeration oil that has flowed out to the crank chamber (153) flows into the oil groove (176). The housing-side flow path (177) is formed in the housing (150), and its inlet end communicates with the oil groove (176). The fixed-side flow path (178) is formed in the fixed scroll (141), and its inlet end communicates with the housing-side flow path (177). The oil in the fixed-side flow path (178) is supplied to a sliding portion in the thrust direction between the fixed scroll (141) and the movable scroll (160).

[0126] (6-3) Driving behavior When the electric motor (125) rotates the rotary shaft (130), the upper eccentric portion (132) rotates eccentrically, causing the movable scroll (160) to orbit. Refrigerant in the suction pipe (123) flows into the compression mechanism (140) through the suction port (146). The volume of a compression chamber between the movable wrap (162) and the fixed wrap (143) gradually decreases, and the refrigerant is compressed in the compression chamber. The compressed refrigerant flows into the first space (S1). The refrigerant in the first space (S1) flows into the second space (S2) through a passage (not shown) around the compression mechanism (140). Some of the refrigerant flows downward through a core cut (not shown) around the electric motor (125) and is used to cool the electric motor (125). The refrigerant in the first space (S1) flows into the refrigerant circuit (10) through the discharge pipe (124).

[0127] (6-4) Refrigerants and refrigerating oils The refrigerant and refrigeration oil of the second embodiment are basically the same as those of the first embodiment. In other words, any of the refrigerant and refrigeration oils described in the first embodiment can be used as the refrigerant and refrigeration oil of the second embodiment. In the second embodiment, the solution viscosity can be measured, for example, by a viscometer attached to the casing (121). The viscometer is attached to the body (121a) or the lower head (121c) of the casing (121). The viscometer can measure the solution viscosity of the first refrigeration oil in the oil reservoir (135) of h1 or less.

[0128] In the second embodiment, the refrigeration oil located at a height position h1 or lower of the suction port (171a) of the oil supply pump (171) is defined as the first refrigeration oil. In the second embodiment, the first refrigeration oil has a first refrigeration viscosity η1, which is the lower limit of the refrigeration viscosity, of 5.0 mPa·s. In other words, the refrigeration oil has a refrigeration viscosity η of 5.0 mPa·s or higher. This reduces the amount of wear on the sliding parts of the scroll compressor (120). The sliding parts referred to here include not only the upper bearing (152), the lower bearing (156), and the pin bearing (157), but also the sliding parts in the thrust direction between the fixed scroll (141) and the movable scroll (160). The relationship between the amount of wear and the refrigeration oil solubility is the same as that shown in FIG. 7, and therefore will not be described in detail.

[0129] In the second embodiment, the second solution viscosity η2, which is the upper limit of the solution viscosity of the first refrigeration oil, is examined. Fig. 10 shows the results of examining the relationship between the solution viscosity of the refrigeration oil, the displacement volume Vcs of the scroll type compression mechanism, and the bearing loss ratio γ2. The line segment L4 in Fig. 10 indicates the relationship between the displacement volume Vcs and the bearing loss ratio γ2. 98 cc compressor, line L5 is a compressor with a displacement volume Vcs of 56cc, line L6 is a compressor with a displacement volume Vcs of 35 cc compressor. Figure 10 shows the relationship between the solution viscosity of refrigeration oil and the bearing loss ratio γ2 for three scroll compressors with different displacement volumes Vcs.

[0130] The displacement volume Vcs is the maximum volume of the compression chamber when it is completely closed by the compression mechanism. The bearing loss ratio γ2 is the ratio [%] of the bearing sliding loss [W] to the compressor input [W]. Strictly speaking, the bearing sliding loss here is the sum of the sliding losses of the upper bearing, lower bearing, and pin bearing.

[0131] As can be seen from Figure 10, the displacement volume Vcs Small As a result, the bearing loss ratio γ2 becomes large. As the displacement volume Vcs of the compression mechanism increases, the size of each bearing also increases. , the area of ​​the sliding part becomes larger 。 As can be seen from Figure 10, the bearing loss ratio γ2 increases as the solution viscosity of the refrigerating machine oil increases. This is because the sliding loss of the bearing increases as the solution viscosity of the refrigerating machine oil increases.

[0132] Taking the above points into consideration, based on the displacement volume Vcs, the soluble viscosity of the refrigeration oil, and the bearing loss ratio γ2 shown in Figure 10, we obtained the relational expression (2) for the upper limit of the soluble viscosity (second soluble viscosity η2) to keep the bearing loss ratio γ2 at 10% or less.

[0133] η2=(0.000195×Vcs+0.0696) / 0.00714 Equation (2) Here, Vcs in the relational expression (2) is the displacement volume [cc] of the compression mechanism (140) described above. By setting the solution viscosity of the refrigeration oil to η2 or less, the bearing loss ratio γ2 can be set to 10% or less. In other words, when Vcs is in the range shown in FIG. 10, it is preferable to set the solution viscosity to 10 [mPa s] or less.

[0134] In the second embodiment, the solution viscosity η of the first refrigeration oil is equal to or less than (0.000195×Vcs+0.0696) / 0.00714. Therefore, in the second embodiment, the sliding loss of each bearing (44, 45) of the compression mechanism (140) can be reduced to 10% or less of the input power of the compressor (120). Here, the sliding loss of each bearing (152, 156, 157) accounts for a large proportion of the overall mechanical loss of the scroll compressor (120). Therefore, by setting the bearing loss ratio γ2 to 10% or less, a decrease in the efficiency of the scroll compressor (120) can be effectively suppressed.

[0135] (7) Other embodiments The rotary compressor may be a so-called rolling piston type in which a roller rotates eccentrically while a vane separate from the roller is in contact with the roller, or a so-called hinge vane type in which the roller rotates eccentrically with the tip of the vane rotatably fitted in a recess on the outer circumferential surface of the roller.

[0136] The compression mechanism (40) may have only one cylinder or may have three or more cylinders, i.e., the compression mechanism (40) may have only one compression section or may have three or more compression sections.

[0137] Scroll compressors may be of the asymmetric or symmetric type.

[0138] The air conditioner (1) may be an indoor multi-type having multiple indoor units. The air conditioner (1) may be a mobile type that adjusts the temperature of air in a target space such as a vehicle. The refrigeration cycle device may be a hot water supply device for generating hot water or a cooling device for generating cold water. The refrigeration cycle device may be an internal cooling device that cools the air inside the storage unit. The internal cooling device may be a stationary type intended for use in a warehouse, or a mobile type intended for use inside a shipping container or trailer.

[0139] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate as long as the functionality of the subject matter of the present disclosure is not impaired.

[0140] The terms "first," "second," "third," etc. mentioned 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]

[0141] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for compressors and refrigeration cycle devices. [Explanation of symbols]

[0142] 1. Air conditioning equipment (refrigeration cycle equipment) 10 Refrigerant circuit 20,120 compressor 21,121 casing 25,125 Electric motor 30,130 Rotation axis 32A,32B,132 Eccentric part 40,140 Compression mechanism 44, 45, 152, 156, 157 bearings 51A, 51B cylinder 52A, 52B Roller 53A, 53B vanes 70,170 Refueling mechanism 71,171 fuel pumps 71a,171a Intake port 72,172 fuel lines A axis center

Claims

1. Electric motor (25,125) and a rotating shaft (30, 130) connected to the electric motor (25, 125); bearings (44, 45, 152, 156, 157) that rotatably support the rotary shaft (30, 130); a compression mechanism (40, 140) driven by the rotary shaft (30, 130) and compressing a refrigerant; A fuel supply mechanism (70, 170), a casing (21, 121) that houses the electric motor (25, 125), the rotating shaft (30, 130), the bearings (44, 45, 152, 156, 157), the compression mechanism (40, 140), and the oil supply mechanism (70, 170) and is filled with high-pressure refrigerant discharged from the compression mechanism (40, 140), The rotating shaft (30, 130) has a shaft body (31, 131) and an eccentric portion (32A, 32B, 132) that is eccentric from the axis of the shaft body (31, 131), The oil supply mechanism (70, 170) an oil supply pump (71, 171) having a suction port (71a, 171a) for sucking refrigeration oil from an oil reservoir (35, 135) at the bottom of the casing (21, 121); an oil supply passage (72, 172) that supplies the oil sucked through the suction port (71a, 171a) to a sliding portion of the bearing (44, 45, 152, 156, 157) and a sliding portion of the eccentric portion (32A, 32B, 132); The refrigerant is a single refrigerant consisting of a hydrocarbon refrigerant or a mixed refrigerant containing the hydrocarbon refrigerant, The refrigerating machine oil is an oil that separates into two layers when the pressure of the refrigerant is 1.9 [MPa] and the temperature of the refrigerating machine oil is 75°C, the refrigeration oil present in the oil reservoir (35, 135) at a height below the suction port (71a, 171a) has a solution viscosity η of 5.0 mPa·S or more; the compression mechanism is a rotary compression mechanism (40) including annular cylinders (51A, 51B), annular rollers (52A, 52B) that rotate eccentrically in the cylinders (51A, 51B), and vanes (53A, 53B) that form compression chambers in the cylinders (51A, 51B), When the displacement volume of the rotary compression mechanism (40) is defined as Vc [cc], The solution viscosity η is (-0.00101 x Vc + 0.12286) / (0.0000146 x Vc + 0.00505) or less Compressor.

2. An electric motor (25,125), a rotating shaft (30, 130) connected to the electric motor (25, 125); bearings (44, 45, 152, 156, 157) that rotatably support the rotary shaft (30, 130); a compression mechanism (40, 140) driven by the rotary shaft (30, 130) and compressing a refrigerant; A fuel supply mechanism (70, 170), a casing (21, 121) that houses the electric motor (25, 125), the rotating shaft (30, 130), the bearings (44, 45, 152, 156, 157), the compression mechanism (40, 140), and the oil supply mechanism (70, 170) and is filled with high-pressure refrigerant discharged from the compression mechanism (40, 140), The rotating shaft (30, 130) has a shaft body (31, 131) and an eccentric portion (32A, 32B, 132) that is eccentric from the axis of the shaft body (31, 131), The oil supply mechanism (70, 170) an oil supply pump (71, 171) having a suction port (71a, 171a) for sucking refrigeration oil from an oil reservoir (35, 135) at the bottom of the casing (21, 121); an oil supply passage (72, 172) that supplies the oil sucked through the suction port (71a, 171a) to a sliding portion of the bearing (44, 45, 152, 156, 157) and a sliding portion of the eccentric portion (32A, 32B, 132); The refrigerant is a single refrigerant consisting of a hydrocarbon refrigerant or a mixed refrigerant containing the hydrocarbon refrigerant, The refrigerating machine oil is an oil that separates into two layers when the pressure of the refrigerant is 1.9 [MPa] and the temperature of the refrigerating machine oil is 75°C, the refrigeration oil present in the oil reservoir (35, 135) at a height below the suction port (71a, 171a) has a solution viscosity η of 5.0 mPa·S or more; the compression mechanism is a scroll-type compression mechanism (140) having a fixed scroll (141) and a movable scroll (160), When the displacement volume of the scroll compression mechanism (140) is defined as Vcs [cc], The solution viscosity η is (0.000195 × Vcs + 0.0696) / 0.00714 or less. Compressor.

3. The refrigerating machine oil contains any one of polyalkylene glycol, polyvinyl ether, and polyol ester. The compressor according to claim 1 or 2.

4. The refrigerating machine oil contains at least one of an extreme pressure additive of a phosphate ester, an antioxidant, and an acid scavenger. The compressor according to claim 1 or 2.

5. The refrigerating machine oil contains 0.1 wt % or more and 0.5 wt % or less of the antioxidant or the acid scavenger. The compressor according to claim 4.

6. The refrigerating machine oil contains 1.0 wt % or more and 5.0 wt % or less of the extreme pressure additive. The compressor according to claim 4.

7. The molecular weight of the refrigerating machine oil is 1,000 or more and 1,800 or less. The compressor according to claim 3.

8. A refrigerant circuit (10) comprising the compressor (20, 120) according to claim 1 or 2, in which the hydrocarbon refrigerant circulates to perform a refrigeration cycle. Refrigeration cycle equipment.

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