Compressors and refrigeration cycle equipment

Abstract

To provide a compressor that can suppress wear on sliding parts. [Solution] The refrigerant is a single refrigerant consisting of a hydrocarbon refrigerant, or a mixed refrigerant containing a hydrocarbon refrigerant. In the oil reservoir (35), the dissolved viscosity η of the refrigerant oil present at or below the height of the suction port (71a) is 5.0 [mPa·S] or higher.

Description

Technical Field

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

Background Art

[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, the refrigerant in the refrigerant circuit circulates, and a refrigeration cycle is performed.

[0003] In the compressor, the refrigerant compressed by the compression mechanism flows out from the discharge pipe into the refrigerant circuit through the space inside the casing. Thus, the inside of the casing is filled with high-pressure refrigerant.

[0004] An oil reservoir for storing refrigeration oil is formed at the bottom of the casing. The refrigeration oil is used to lubricate the sliding parts of the compressor. The refrigeration oil in the oil reservoir is sucked from the suction port of the oil supply pump and supplied to the sliding parts of the bearing and the sliding parts of the eccentric part through the oil supply passage in the rotating shaft.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Hydrocarbon refrigerants, such as propane, are used as refrigerants in the refrigerant circuits of refrigeration cycle systems. Hydrocarbon refrigerants are natural refrigerants and have an extremely low global warming potential. On the other hand, hydrocarbon refrigerants have hydrocarbon bonds, similar to refrigeration oil, and have a similar molecular structure, so they dissolve easily in refrigeration oil. For this reason, if hydrocarbon refrigerant dissolves into the refrigeration oil inside the compressor casing, the solubility viscosity of the refrigeration oil may decrease. If such refrigeration oil is supplied to the sliding parts of bearings or eccentric parts, the amount of wear on the sliding parts will increase.

[0007] The purpose of this disclosure is to provide a compressor that can suppress wear on sliding parts. [Means for solving the problem]

[0008] The first embodiment relates to a compressor. The compressor comprises 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 rotating shaft (30, 130), a compression mechanism (40, 140) driven by the rotating shaft (30, 130) to compress a refrigerant, a lubrication 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 lubrication 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 eccentric portions (32A,32B,132) that are eccentric to the axis of the shaft body (31,131). The lubrication mechanism (70,170) includes a lubrication pump (71,171) having suction ports (71a,171a) for drawing in refrigerant oil from an oil reservoir (35,135) at the bottom of the casing (21,121), and a lubrication passage (72,172) for supplying the oil drawn in from the suction ports (71a,171a) to the sliding parts of the bearings (44,45,152,156,157) and the sliding parts of the eccentric portions (32A,32B,132). The refrigerant is a single refrigerant consisting of a hydrocarbon refrigerant, or a mixed refrigerant containing the hydrocarbon refrigerant. The refrigerant oil is an oil that separates into two layers when the refrigerant pressure is 1.9 [MPa] and the temperature of the refrigerant oil is 75°C. In the oil reservoirs (35, 135), the dissolved viscosity η of the refrigerant oil present at or below the height of the suction ports (71a, 171a) is 5.0 [mPa·S] or higher.

[0009] In the first embodiment, refrigerant oil from the oil reservoirs (35, 135) flows through the suction ports (71a, 171a) to the oil supply passages (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 dissolved viscosity η of the refrigerant oil present below the height of the suction ports (71a, 171a) is 5.0 [mPa·S] or higher. Therefore, it is possible to suppress the supply of low-viscosity refrigerant oil to the sliding parts. As a result, wear on the sliding parts can be suppressed.

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

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

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

[0013] If the dissolution viscosity of the refrigerant oil becomes too high, the sliding loss in the sliding parts increases, leading to increased mechanical losses. Here, the sliding loss of the eccentric parts (32A, 32B) is affected by the projected area when the eccentric parts (32A, 32B) are viewed from the radially outer side. The projected area of ​​the eccentric parts (32A, 32B) increases as the displacement volume Vc of the rotary compression mechanism (40) increases. After considering the above points, it was found that the upper limit of the dissolution viscosity to suppress the sliding loss of the eccentric parts (32A, 32B) can be expressed by the above function equation including the displacement volume Vc [cc]. In the third embodiment, the dissolution viscosity η is kept below this upper limit, so that the sliding loss of the eccentric parts (32A, 32B) does not become excessively high.

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

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

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

[0017] If the dissolution viscosity of the refrigeration oil becomes too high, the sliding loss in the sliding parts increases, leading to increased mechanical losses. In this case, the sliding loss of the scroll compressor is predominantly due to the sliding loss of the bearings. The area of ​​the sliding part of the bearing increases as the displacement volume Vcs of the scroll compression mechanism (140) increases. After considering the above points, it was found that the upper limit of the dissolution viscosity to suppress the sliding loss of the bearings (152, 156, 157) can be expressed by the above function equation including the displacement volume Vcs [cc]. In the fifth embodiment, the dissolution viscosity η is kept below this upper limit, so that the sliding loss of the sliding parts and eccentric parts does not become excessively high.

[0018] The sixth embodiment is one in which, in any one of the first to fifth embodiments, the refrigeration oil comprises polyalkylene glycol, polyvinyl ether, or polyvinyl ether.

[0019] In the sixth embodiment, the refrigeration oil comprises polyalkylene glycol, polyvinyl ether, or polyol ester. These refrigeration oils are relatively insoluble in hydrocarbon refrigerants. Therefore, it is possible to suppress the excessive decrease in the solubility viscosity of the refrigeration oil caused by the dissolution of hydrocarbon refrigerants into the refrigeration oil.

[0020] The seventh embodiment is that, in any one of the first to sixth embodiments, the refrigeration oil contains at least one of a phosphate ester extreme pressure additive, an antioxidant, and an acid scavenger.

[0021] The eighth aspect is that, in any one of the first to seventh aspects, the refrigeration oil contains 0.1% or more by weight and 0.5% or less by weight of an antioxidant or acid scavenger.

[0022] In the eighth aspect, an antioxidant or an acid scavenger is set to 0.5% by weight or less based on the weight of the refrigeration oil, so that it is possible to suppress the excessive decrease in the dissolved viscosity of the refrigeration oil due to an increase in the content of the antioxidant or the acid scavenger.

[0023] The ninth aspect is that, in any one of the first to eighth aspects, the refrigeration oil contains an extreme pressure additive of 1.0% by weight or more and 5.0% by weight or less.

[0024] In the ninth aspect, the extreme pressure additive is set to 5.0% by weight or less based on the weight of the refrigeration oil, so that it is possible to suppress the excessive decrease in the dissolved viscosity of the refrigeration oil due to an increase in the content of the extreme pressure additive.

[0025] The tenth aspect is that, in any one of the first to ninth aspects, the molecular weight of the refrigeration oil is 1000 or more and 1800 or less.

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

[0027] The eleventh aspect is directed to a refrigeration cycle apparatus. The refrigeration cycle apparatus includes any one of the first to tenth compressors (20) and a refrigerant circuit (10) in which a hydrocarbon refrigerant circulates to perform a refrigeration cycle.

Brief Description of Drawings

[0028] [Figure 1] FIG. 1 is a piping system diagram of the refrigeration cycle apparatus according to Embodiment 1. [Figure 2] FIG. 2 is a longitudinal 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]Figure 6 is a table showing the test conditions for the evaluation test of the amount of wear on the sliding parts. [Figure 7] Figure 7 is a graph showing the relationship between the amount of wear on the sliding parts and the solubility viscosity of the refrigerant oil. [Figure 8] Figure 8 is a graph showing the relationship between the dissolution viscosity of refrigerant oil and the loss ratio at the eccentric part in several compressors with different displacement volumes. [Figure 9] Figure 9 is a longitudinal cross-sectional view of the compressor of Embodiment 2. [Figure 10] Figure 10 is a graph showing the relationship between the dissolution viscosity of refrigerant oil and the bearing loss ratio in several compressors with different displacement volumes. [Modes for carrying out the invention]

[0029] Embodiments of this disclosure will be described in detail below with reference to the drawings. This disclosure is not limited to the embodiments shown below, and various modifications are possible without departing from the technical idea of ​​this disclosure. Since the drawings are for conceptual illustration of this disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.

[0030] <Embodiment 1> (1) Overall structure The refrigeration cycle system of this disclosure is applicable to a stationary air conditioning system (1). As shown in Figure 1, the air conditioning system (1) is a paired system 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 conditioning system (1) has a refrigerant circuit (10). The refrigerant circuit (10) is filled with 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 installed in the outdoor unit (OU), and the indoor heat exchanger (13) is installed in the indoor unit (IU). The expansion valve (12) may also be installed in the indoor unit (IU).

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

[0033] The four-way directional control valve (14) has a first port (P1), a second port (P2), a third port (P3), and a fourth port (P4). The four-way directional control valve (14) switches between a first state, shown by the solid line in Figure 1, and a second state, shown by the dashed line in Figure 1. In the first state, the four-way directional control valve (14) connects the first port (P1) and the second port (P2) and simultaneously connects the third port (P3) and the fourth port (P4). When the four-way directional control valve (14) is in the first state, the compressor (20) is operated, and a cooling cycle is performed in which the outdoor heat exchanger (11) functions as a heat radiator (condenser) and the indoor heat exchanger (13) functions as an evaporator. In the second state, the four-way switching valve (14) connects the first port (P1) and the third port (P3) while simultaneously connecting the second port (P2) and the fourth port (P4). When the four-way switching valve (14) is in the second state, the compressor (20) is operated, and 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 explained with reference to Figures 2 to 5. In the following explanation, the terms "up" and "down" refer to the directions indicated by the arrows in Figure 2. In the following explanation, "axial direction" means the direction in which the axis (A) of the rotating shaft (30) shown in Figure 2 extends, "radial direction" means the direction that passes through the axis (A) of the rotating shaft (30) and is perpendicular to the axis (A), and "circumferential direction" means the direction of rotation of the rotating shaft (30).

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

[0036] The compressor (20) has a casing (21) and a plurality of component parts housed in the casing (21). The plurality of component parts include an electric motor (25), a rotating shaft (30), a rotary compression mechanism (40), bearings (44, 45), and a lubrication mechanism (70). The electric motor (25) is the 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) compresses the refrigerant by being rotationally driven by the rotating shaft (30). The lubrication mechanism (70) supplies refrigerant oil, which is a lubricating oil, 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 vertically, extending axially, or more precisely, vertically. The casing (21) has a vertically extending cylindrical body (21a), an upper lid (21b) that closes the upper end of the body (21a), and a lower lid (21c) that closes the lower end of the body (21a). The lower lid (21c) constitutes the bottom of the casing (21).

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

[0039] An oil reservoir (35) for storing refrigerant oil is formed at the bottom of the casing (21). In the oil reservoir (35), the oil level of the refrigerant oil changes according to the operating conditions of the compressor (20) and the air conditioning unit (1).

[0040] (2-2) First inhalation tube, second inhalation tube, and discharge tube The casing (21) is connected to a first suction pipe (23A), a second suction pipe (23B), and a discharge pipe (24). The first suction pipe (23A) and the second suction pipe (23B) pass radially through the body (21a). The first suction pipe (23A) and the second suction pipe (23B) are connected to the low-pressure line of the refrigerant circuit (10). The discharge pipe (24) passes axially through the upper cover (21b). The discharge pipe (24) is connected to the 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 circumferential surface of the body (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 positioned radially inward of the stator (26). The rotor (27) is fixed to the outer circumferential surface of the rotating shaft (30). The electric motor (25) is configured so that its rotational speed can be adjusted by an inverter device. In other words, the electric motor (25) is an inverter-type electric motor with a variable operating frequency.

[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) that are radially eccentric from the axis (A) of the shaft body (31). The rotor (27) of the electric motor (25) is connected to the upper part of the shaft body (31). The first eccentric portion (32A) and the second eccentric portion (32B) are formed at the lower part 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 axis (A) and the direction in which the second eccentric portion (32B) is eccentric from the axis are offset by 180° from each other in the circumferential direction.

[0043] (2-5) Overall configuration of the compression mechanism The compression mechanism (40) is located below the electric motor (25). The compression mechanism (40) has, 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 components are fastened to each other by bolts that extend axially.

[0044] The compression mechanism (40) of this embodiment comprises a first compression element (C1) and a second compression element (C2). The first compression element (C1) has a first roller (52A) and a first vane (53A). The second compression element (C2) has a second roller (52B) and a second vane (53B). In the compression mechanism (40) of this embodiment, the rollers (52A, 52B) and vanes (53A, 53B) are integrally configured, 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) penetrates 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) penetrates the second cylinder (51B) in the axial direction.

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

[0047] The lower surface of the first closure portion (41a) closes the upper opening surface of the first cylinder chamber (54A). As shown in Figure 4, the first closure portion (41a) has 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 that extends axially along the rotating shaft (30). The rotating shaft (30) passes through the interior of the upper bearing portion (41b). A first bearing (44) is formed on the inner circumferential 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 composed of a sliding bearing, more precisely a journal bearing.

[0049] The middle plate (42) is positioned between the first cylinder (51A) and the second cylinder (51B). The middle plate (42) is formed in an annular shape. The rotating shaft (30) passes through the interior of 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 closure portion (43a) which is a flat plate with a slightly thicker wall in the axial direction, and a lower bearing portion (43b) which extends downward from the radial center of the second closure portion (43a). The upper surface of the second closure portion (43a) closes the lower opening surface of the second cylinder chamber (54B). As shown in Figure 5, the second closure portion (43a) has a second discharge port (55B) which 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 that extends axially along the rotating shaft (30). The rotating shaft (30) passes through the interior of the lower bearing portion (43b). A second bearing (45) is formed on the inner circumferential surface of the lower bearing portion (43b). The second bearing (45) rotatably supports the sub-shaft portion of the rotating shaft (30). The second bearing (45) is composed of a sliding bearing, more precisely a journal bearing.

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

[0053] The first cylinder (51A) is an annular member that is slightly thicker in the axial direction. Inside the first cylinder (51A), a first cylinder chamber (54A) is formed. The first cylinder chamber (54A) is formed in a circular shape when viewed in the axial direction. The first cylinder (51A) has a first intake passage (57A) and a first bush groove (58A) formed therein. The first intake passage (57A) penetrates the first cylinder (51A) radially. The first intake passage (57A) communicates with the first intake pipe (23A).

[0054] The first roller (52A) is positioned 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 part (32A) is fitted inside the first roller (52A). The inner circumferential surface of the first roller (52A) and the outer circumferential surface of the first eccentric part (32A) slide relative to each other. The first eccentric part (32A) causes the first roller (52A) to rotate eccentrically. The first roller (52A) rotates eccentrically along the inner circumferential surface of the first cylinder chamber (54A), forming a seal between itself and the inner circumferential surface of the first cylinder chamber (54A).

[0055] The first bush groove (58A) is formed on the top dead center side (upper side in Figure 3) of the first cylinder (51A). The first bush groove (58A) is formed in a circular shape when viewed in the axial direction. A pair of first bushes (56A) fit into the first bush groove (58A). Each pair of first bushes (56A) has an arc-shaped portion that follows the inner surface of the first bush groove (58A) and flat portions that are continuous with both ends of the arc-shaped portion. The pair of first bushes (56A) are arranged in the first bush groove (58A) so that their respective flat portions face each other. The flat portions of the pair of first bushes (56A) hold the first vane (53A). The pair of first bushes (56A) are configured to swing along the inner surface of the first bush groove (58A). The first vane (53A) is configured to reciprocate radially between the pair of first bushes (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). The radially inner portion of the first vane (53A) is continuous with the outer 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 Figure 5 has a second eccentric portion (32B), a second cylinder (51B), a second roller (52B), a second vane (53B), and a pair of second bushes (56B). The basic structure of the second eccentric portion (32B), second cylinder (51B), second roller (52B), second vane (53B), and pair of second bushes (56B) is the same as that of the first eccentric portion (32A), first cylinder (51A), first roller (52A), first vane (53A), and pair of first bushes (56A), respectively, so a detailed explanation is omitted. The second cylinder (51B) has a second cylinder chamber (54B), a second intake passage (57B), and a second bush groove (58B). The basic structure of the second cylinder chamber (54B), the second intake passage (57B), and the second bush groove (58B) is the same as that of the first cylinder chamber (54A), the first intake passage (57A), and the first bush groove (58A), respectively, so a detailed explanation is omitted. The second intake passage (57B) is connected to the second intake pipe (23B). The first roller (52A) and the second roller (52B) are 180° out of phase with respect to each other during eccentric rotation.

[0058] (2-6) Fueling mechanism The lubrication mechanism (70) shown in Figure 3 supplies refrigerant oil from the oil reservoir (35) to multiple sliding parts. The lubrication mechanism (70) is located at the bottom of the rotating shaft (30). The lubrication mechanism (70) includes a lubrication pump (71) and a lubrication passage (72).

[0059] The oil supply pump (71) is located at the lower end of the rotating shaft (30). The oil supply pump (71) is positioned lower than the oil level in the oil reservoir (35). The oil supply pump (71) transports the refrigerant oil from the oil reservoir (35). The oil supply pump (71) has a suction port (71a) for drawing in the refrigerant 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 rotating shaft (30). The oil supply passage (72) communicates with the discharge side of the oil supply pump (71). The oil supply passage (72) has a main passage (73) that extends vertically through the axis of the rotating shaft (30) and a plurality of branch passages that extend radially from the main passage (73). The plurality of branch passages include, in order from top to bottom, a first branch passage (74a), a second branch passage (74b), a third branch passage (74c), and a fourth branch passage (74d).

[0061] The first branch channel (74a) is located at the same height as the upper bearing (41b). The 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 part between the first bearing (44) and the rotating shaft (30). The second branch channel (74b) is formed in the first eccentric part (32A). The 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 part between the first roller (52A) and the first eccentric part (32A). The third branch channel (74c) is formed in the second eccentric part (32B). The 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 part between the second roller (52B) and the second eccentric part (32B). The fourth branch channel (74d) is at the same height as the lower bearing part (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 part between the second bearing (45) and the rotating shaft (30).

[0062] (2-7) Operating procedures When the rotating shaft (30) is rotated by the electric motor (25), the first eccentric part (32A) and the second eccentric part (32B) rotate eccentrically. In the first compression element (C1), as the first roller (52A) rotates eccentrically, low-pressure refrigerant is drawn from the first suction pipe (23A) into the low-pressure chamber (L) of the first cylinder chamber (54A). 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), as the second roller (52B) rotates eccentrically, low-pressure refrigerant is drawn from the second suction pipe (23B) into the second low-pressure chamber (L) of the first cylinder chamber (54A). At the same time, the refrigerant is compressed in the high-pressure chamber (54B) of the second cylinder chamber (54B).

[0063] When the internal pressure in the compression chamber of the first compression element (C1) rises 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 in the compression chamber of the second compression element (C2) rises 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 surrounding the compression mechanism (40) passes above the electric motor (25) and is discharged into the refrigerant circuit (10) via the discharge pipe (24).

[0064] As the rotating shaft (30) rotates, the oil supply pump (71) rotates along with the rotating shaft (30). As a result, the refrigerant oil in the oil reservoir (35) is drawn into the suction port (71a). The oil supply pump (71) sends the refrigerant oil drawn in from the suction port (71a) to each branch channel (71a, 71b, 71c, 71d) via the main channel (73). The refrigerant oil in the first branch channel (74a) is used to lubricate the sliding part of the first bearing (44), the refrigerant oil in the second branch channel (74b) is used to lubricate the sliding part of the first eccentric part (32A), the refrigerant oil in the third branch channel (74c) is used to lubricate the sliding part of the second eccentric part (32B), and the refrigerant oil in the fourth branch channel (74d) is used to lubricate the sliding part 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 consisting 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 refrigeration oil, and therefore have the characteristic of being easily soluble in refrigeration 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 include HFC (hydrofluorocarbon) refrigerants, HFO (hydrofluoroolefin) refrigerants, and CF3I (trifluoroiodomethane).

[0067] (4) Refrigerating machine oil Next, the refrigerant oil used in the refrigerant circuit (10) will be explained. Here, refrigerant oil refers to a fluid that contains additives such as extreme pressure additives, antioxidants, and acid scavengers, in addition to the components used for lubricating sliding parts (lubricating oil).

[0068] (4-1) Components and properties of refrigerant oil The refrigerant oil used in the refrigerant circuit (10) of this embodiment contains either PAG (polyalkylene glycol), PVE (polyvinyl ether), or POE (polyol ester). The refrigerant oil is mainly composed of PAG, PVE, or POE.

[0069] Hydrocarbon refrigerants such as propane have a molecular structure similar to that of refrigeration oil, and therefore dissolve easily in refrigeration oil. In contrast, PAG, PVE, or POE have relatively low compatibility with hydrocarbon refrigerants. For this reason, using PAG, PVE, or POE as the refrigeration oil can suppress the dissolution of the refrigerant into the oil. The refrigeration oil may also be alkylbenzene or mineral oil.

[0070] The refrigerant oil has the characteristic of separating into two layers when the refrigerant pressure is 1.9 MPa and the temperature of the refrigerant oil is 75°C. Therefore, the refrigerant 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 refrigerant oil is 75°C.

[0071] Generally, refrigerant oil dissolves uniformly with refrigerant. However, by using refrigerant oil with low solubility with refrigerant, a concentration gradient between the refrigerant oil and refrigerant is created in the oil reservoir (35), resulting in a so-called two-layer separation of the refrigerant oil. The refrigerant oil near the surface of the oil reservoir (35) has a lower refrigerant density, forming a layer with high refrigerant solubility. The refrigerant oil near the bottom of the oil reservoir (35) has a higher refrigerant density, forming a layer with low refrigerant solubility. The dissolution viscosity of the refrigerant oil changes depending on the refrigerant solubility. Therefore, the dissolution viscosity of the refrigerant oil can be ensured by suppressing the refrigerant solubility. When refrigerant and refrigerant oil are mixed, the state in which the refrigerant and refrigerant oil do not dissolve and separate into two layers, or an emulsion state, is called a two-layer separation state.

[0072] The molecular weight of the refrigeration oil is preferably between 1000 and 1800.

[0073] The refrigeration oil contains at least one additive, which is an extreme pressure additive of phosphate esters, an antioxidant, and an acid scavenger.

[0074] As extreme pressure additives of phosphate esters, those containing phosphate esters, phosphite esters, acidic phosphate esters, acidic phosphite esters, and amine salts of acidic phosphite esters can be used.

[0075] As acid scavengers, epoxy compounds such as phenyl glycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, α-olefin oxide, and epoxidized soybean oil can be used.

[0076] For antioxidants, phenol-based antioxidants or amine-based antioxidants can be used.

[0077] The refrigeration oil contains 1.0% to 5.0% by weight of extreme pressure additives. The refrigeration oil also contains 0.1% to 0.5% by weight of antioxidants or acid scavengers.

[0078] The refrigerant 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 refrigerant oil is measured according to the method conforming to JIS K2241.

[0079] (4-2) Dissolution viscosity of refrigerant oil in oil reservoirs The dissolution viscosity of the refrigerant oil in the oil reservoir (35) of the compressor (20) casing (21) will be described in detail. The refrigerant oil located at or below the height position h1 of the suction port (71a) of the oil supply pump (71) in the oil reservoir (35) is defined as the first refrigerant oil. The height position h1 of the suction port (71a) means the absolute height of the horizontal plane passing through the suction port (71a). In this embodiment, the dissolution viscosity η of the first refrigerant oil is between a first dissolution viscosity η1 and a second dissolution viscosity η2. In other words, the refrigerant oil is configured such that the dissolution viscosity η of the first refrigerant oil in the oil reservoir (35) is in the range of η1 or more and η2 or less. Here, "dissolution viscosity" means the viscosity of the fluid in which the refrigerant is dissolved in the refrigerant oil. The viscosity of this fluid is measured by a method conforming to JIS K2283. The dissolution viscosity of the refrigerant oil changes depending on the content of the extreme pressure additives, antioxidants, or oxygen scavengers mentioned above.

[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 is, for example, in the range of 72-80 [°C], and the pressure is 1.9 [MPa]. Therefore, under these operating conditions, the refrigerant oil is configured such that the dissolution viscosity η of the first refrigerant oil at 72-80 [°C] and 1.9 [MPa] is between a first dissolution viscosity η1 and a second dissolution viscosity η2. The dissolution 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 lid (21c) of the casing (21). The viscometer can measure the dissolution viscosity of the first refrigerant oil in the oil reservoir (35) that is less than or equal to h1.

[0081] (4-2-1) Lower limit of dissolution viscosity The lower limit of the dissolution viscosity of the first refrigerant oil, the first dissolution viscosity η1, is 5.0 [mPa·s]. In other words, the dissolution viscosity η of the first refrigerant oil is 5.0 [mPa·s] or higher. This reduces the amount of wear on each sliding part, such as the first bearing (44), the second bearing (45), the first eccentric part (32A), and the second eccentric part (32B). The test results verifying the relationship between the amount of wear on these sliding parts and the dissolution viscosity of the refrigerant oil will be explained with reference to Figures 6 and 7.

[0082] Figure 6 shows the test conditions for this test. The amount of wear on 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 specimen (pin). Propane (as a hydrocarbon refrigerant) was dissolved in refrigeration oil, and several refrigeration oils with different dissolution viscosities were blended. For each refrigeration oil, a test specimen (pin) lubricated with the refrigeration oil was sandwiched between two blocks and rotated for 60 minutes with a predetermined load (150 [lbs]) applied, and the amount of wear at this time was measured. At this time, the ambient temperature of the test specimen was set to 80°C, which corresponds to the temperature inside the casing (21) in a normal refrigeration cycle.

[0083] Figure 7 shows the relationship between the dissolution viscosity of the refrigerant oil and the amount of wear on the test specimen, as measured by the FALEX test. The test results showed that no wear on the test specimen occurred in the range of dissolution viscosity from 6 [mPa·s] to 10 [mPa·s]. When the dissolution viscosity was less than 6 [mPa·s], wear occurred on the test specimen, and it was confirmed that the amount of wear increased sharply when the dissolution viscosity was less than 5 [mPa·s]. When the dissolution viscosity is 5 [mPa·s] or higher, the amount of wear can be kept to 1 [mg] or less. From this, it is desirable to set the dissolution viscosity to 5.0 [mPa·s] or higher in order to suppress wear on the sliding parts. In the compressor (20) of this embodiment, wear on the sliding parts can be appropriately suppressed by using refrigerant oil with a dissolution viscosity of 5.0 [mPa·s] or higher.

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

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

[0086] The displacement volume Vc is the volume of the high-pressure chamber (compression chamber) when the low-pressure chamber is completely closed within the cylinder and the high-pressure chamber (compression chamber) is formed, and corresponds to the maximum volume of the compression chamber. If the compression mechanism is a two-cylinder type, the 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 the displacement volume Vc is the sum of these individual displacement volumes Vc-n, Vc-n+1, ​​...

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

[0088] As can be seen from Figure 8, as the displacement volume Vc increases, the loss ratio γ of the eccentric part increases. When the displacement volume Vc of the compression mechanism increases, the size of the eccentric part increases, and the projected area when the eccentric part is viewed from the radially outer side increases. When the eccentric part rotates eccentrically, a load acts from the eccentric part to the roller in the area corresponding to this projected area, and this load greatly affects the sliding loss [W]. Therefore, as the displacement volume Vc increases, the projected area increases, and the sliding loss, and furthermore the loss ratio γ of the eccentric part, increases.

[0089] As can be seen from Figure 8, the loss ratio γ at the eccentric part increases as the dissolution viscosity of the refrigerant oil increases. This is because the sliding loss at the eccentric part increases as the dissolution viscosity of the refrigerant oil increases.

[0090] Considering the above points, based on the displacement volume Vc shown in Figure 8, the dissolution viscosity of the refrigerant oil, and the loss ratio γ of the eccentric part, we obtained a relational equation (1) for the upper limit of the dissolution viscosity (second dissolution viscosity η2) in order to keep the loss ratio γ of the eccentric part below 10%.

[0091] η² = (-0.00101 × Vc + 0.12286) / (0.0000146 × Vc + 0.00505) ... Relational expression (1) Here, Vc in relation (1) is the displacement volume [cc] of the compression mechanism (40) described above. By making the dissolution viscosity of the refrigerant oil η2 or less, the loss ratio γ of the eccentric part can be made 10% or less.

[0092] In this embodiment, the dissolution viscosity η of the first refrigeration oil is less than or equal to (-0.00101 × Vc + 0.12286) / (0.0000146 × Vc + 0.00505). Therefore, in this embodiment, the sliding loss of the eccentric parts (32A, 32B) of the compression mechanism (40) can be kept to 10% or less of the input to the compressor (20). Here, the sliding loss of the eccentric parts (32A, 32B) accounts for a large proportion of the total mechanical loss of the compressor (20). Therefore, by keeping the loss ratio γ to 10% or less, the decrease in the efficiency of the compressor (20) can be effectively suppressed.

[0093] In addition, a relatively large amount of refrigerant oil is supplied to the sliding parts of the eccentric sections (32A, 32B), so a fluid lubrication region is formed between the eccentric sections (32A, 32B) and the rollers (52A, 52B). For this reason, the sliding loss of the eccentric sections (32A, 32B) is easily affected by the dissolution viscosity of the refrigerant oil. Therefore, by keeping the dissolution viscosity of the refrigerant oil below the upper limit of the above relation (1), the increase in sliding loss of the eccentric sections (32A, 32B) can be effectively suppressed.

[0094] (4-3) Regarding the first refrigeration oil As described above, the first refrigeration oil is the refrigeration oil in the oil reservoir (35) at or below the height of the suction port (71a). However, it is preferable that the first refrigeration oil is the refrigeration oil located below the suction port (71a), near the suction port (71a), or inside the suction port (71a). By setting the dissolution viscosity η of such refrigeration oil to η1 or higher, wear of the sliding parts can be suppressed in particular. By setting the dissolution viscosity η of such refrigeration oil to η2 or lower, sliding losses in the eccentric parts (32A, 32B) can be reduced in particular.

[0095] (5) Effects of Embodiment 1 (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 refrigeration oil, and therefore have the characteristic of being easily soluble in refrigeration oil. As a result, excessive dissolution of the refrigerant into the refrigeration oil may reduce the solubility viscosity of the refrigeration oil. When the solubility viscosity of the refrigeration oil decreases, the viscosity of the refrigeration oil supplied to the sliding parts of the first bearing (44), second bearing (45), first eccentric part (32A), and second eccentric part (32B) also decreases, which may lead to poor lubrication of these sliding parts.

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

[0097] This allows refrigeration oil with a dissolution viscosity of 5.0 [mPa·S] or higher to be supplied to the sliding parts of the bearings (44, 45) and the eccentric parts (32A, 32B). As a result, wear on these sliding parts can be suppressed, improving the reliability of the compressor (20) and extending its lifespan.

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

[0099] This reduces sliding losses in the eccentric sections (32A, 32B). Specifically, the sliding losses in the eccentric sections (32A, 32B) can be kept below 10% of the input to the compressor (20). Therefore, the mechanical losses of the compressor (20) can be reduced, the efficiency of the compressor (20) can be improved, and the COP (Coefficient of Performance) of the refrigerant circuit (10) can be improved.

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

[0101] By using these refrigeration oils, hydrocarbon refrigerants are less likely to dissolve into the refrigeration oil. When hydrocarbon refrigerants dissolve into the refrigeration oil, the solubility viscosity of the first refrigeration oil decreases. Conversely, by using these refrigeration oils, it is possible to suppress the excessive decrease in the solubility viscosity of the first refrigeration oil.

[0102] In particular, by setting the molecular weight of the refrigeration oil to between 1000 and 1800, the dissolution of hydrocarbon refrigerants into the refrigeration oil can be effectively suppressed.

[0103] Since hydrocarbon refrigerants are highly flammable, the amount that can be charged into the refrigerant circuit (10) may be limited. Therefore, if an excessive amount of hydrocarbon refrigerant dissolves into the refrigeration oil, it may not be possible to secure a sufficient amount of refrigerant for use in the refrigeration cycle. 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 secured.

[0104] (5-4) The refrigeration oil contains at least one of the following: extreme pressure additives of phosphate esters, antioxidants, and acid scavengers.

[0105] When refrigerant oil contains antioxidants, it contains 0.1% by weight or more and 0.5% by weight or less of antioxidants. Hydrocarbon refrigerants have a chemically stable structure and are less prone to decomposition during the refrigeration cycle compared to HFC and HFO refrigerants. Therefore, even if the amount of antioxidant is 0.5% by weight or less, the refrigerant can be used stably over the long term. Furthermore, by limiting the amount of antioxidant to 0.5% by weight or less, the decrease in viscosity of the refrigerant oil can be suppressed. As a result, it becomes easier to achieve a dissolution viscosity η of 5.0 [mPa·S] or higher for the first refrigerant oil, thereby suppressing wear on sliding parts. By suppressing the dissolution of hydrocarbon refrigerants into the refrigerant oil in this way, the amount of refrigerant used in the refrigeration cycle can be secured.

[0106] When refrigeration oil contains an acid scavenger, it contains 0.1% to 0.5% by weight of the acid scavenger. As mentioned above, hydrocarbon refrigerants have a chemically stable structure and are less prone to decomposition during the refrigeration cycle compared to HFC and HFO refrigerants. Therefore, even if the amount of acid scavenger is 0.5% by weight or less, the refrigerant can be used stably over the long term. Furthermore, by limiting the amount of acid scavenger to 0.5% by weight or less, the decrease in the viscosity of the refrigeration oil can be suppressed. As a result, it becomes easier to achieve a dissolution viscosity η of 5.0 [mPa·S] or higher for the first refrigeration oil, thereby suppressing wear on sliding parts. By suppressing the dissolution of hydrocarbon refrigerants into the refrigeration oil in this way, the amount of refrigerant used in the refrigeration cycle can be secured.

[0107] When refrigeration oil contains extreme pressure additives, it contains 1.0% to 5.0% by weight of extreme pressure additives. By limiting the amount of extreme pressure additives to 5.0% by weight or less, a decrease in the viscosity of the refrigeration oil can be suppressed. As a result, it becomes easier to achieve a dissolution viscosity η of 5.0 [mPa·S] or higher for the first refrigeration oil, thereby suppressing wear on sliding parts. In this way, by suppressing the dissolution of hydrocarbon refrigerants into the refrigeration oil, the amount of refrigerant used in the refrigeration cycle can be secured.

[0108] <Embodiment 2> The compressor in Embodiment 2 is a scroll compressor (120).

[0109] (6-1) Overall structure As shown in Figure 9, the scroll compressor (hereinafter also referred to as compressor (120)) has a casing (121) and a plurality of component parts housed in the casing (121). The plurality of component parts include an electric motor (125), a rotating shaft (130), a scroll-type compression mechanism (140), bearings (152, 156, 157), and a lubrication mechanism (170). The electric motor (125) is the 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) compresses the refrigerant by being rotationally driven by the rotating shaft (130). The lubrication mechanism (170) supplies refrigerant oil, which is a lubricating oil, 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 formed to be elongated vertically, extending axially, or more precisely, vertically. The casing (121) has a vertically extending cylindrical body (121a), an upper end plate (121b) that closes the upper end of the body (121a), and a lower end plate (121c) that closes the lower end of the body (21a). The lower end plate (121c) forms the bottom of the casing (21).

[0111] The internal space (S) of the casing (121) is filled with discharged refrigerant discharged from the compression mechanism (140). That is, the compressor (120) is 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) is formed at the bottom of the casing (121) where refrigerant oil is stored. In the oil reservoir (135), the oil level of the refrigerant oil changes according to the operating conditions of the compressor (120) and the air conditioning unit (1).

[0113] The casing (121) is connected to an intake pipe (123) and a discharge pipe (124). The intake pipe (123) passes through the upper end plate (121b) in the axial direction. The outlet end of the intake pipe (123) is connected to the intake 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 at the bottom of the internal space (S). The electric motor (125) has 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 rotating shaft (130). The electric motor (125) is configured so that its rotational speed can be adjusted by an inverter device. In other words, the electric motor (125) is an inverter-type electric motor with a variable operating frequency.

[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 on the upper surface of the housing (150). An upper bearing (152) is provided in the lower center 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) from which the upper eccentric part (132) can move.

[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 (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 the upper surface of the housing (150). The movable scroll (160) is positioned 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 lap (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 lap (143) protrudes downward from the fixed end plate (142). In an axial cross-sectional view, the fixed end plate (142) is formed in a spiral shape. 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). An intake port (146) communicating with the intake pipe (123) is formed in the outer peripheral wall (144). A discharge port (147) communicating with the internal space (S) is formed in the central part of the fixed end plate (142).

[0120] The movable scroll (160) has a movable end plate (161), a movable lap (162), and a boss portion (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-sectional view. The boss portion (163) protrudes downward from the center of the movable end plate. The upper eccentric portion (132) fits into the boss portion (163). More precisely, a pin bearing (157) is provided between the inner surface of the boss portion (163) and the upper eccentric portion (132).

[0121] (6-2) Fueling mechanism The lubrication mechanism (170) supplies refrigerant oil from the oil reservoir (135) to multiple sliding parts. The lubrication mechanism (170) is located below the rotating shaft (130). The lubrication mechanism (170) includes a lubrication pump (171) and a lubrication passage (172).

[0122] The fuel pump (171) is located at the lower end of the rotating shaft (130). The fuel pump (171) is positioned lower than the oil level of the oil reservoir (135). The fuel pump (171) transports the refrigerant oil from the oil reservoir (135). The fuel pump (171) has a suction port (171a) for drawing in the refrigerant oil from the oil reservoir (135). The suction port (171a) opens downward toward the bottom of the casing (121). The fuel pump (171) is a differential pressure type, centrifugal type, or positive displacement type pump.

[0123] The oil supply passage (172) communicates with the discharge side of the oil supply pump (171). The oil supply passage (172) has a main passage (173) that extends axially inside the rotating shaft (130) and a plurality of branch passages (174a, 174b, 174c) that extend radially from the main passage (173). The plurality of branch passages include, in order from bottom to top, a fifth branch passage (174a), a sixth branch passage (174b), and a seventh branch passage (174c).

[0124] The fifth branch channel (174a) is at the same height as the lower bearing (156). The outlet of the fifth branch channel (174a) opens toward the lower bearing (156). In other words, the fifth branch channel (174a) opens toward the sliding part between the lower bearing (156) and the rotating shaft (130). The sixth branch channel (174b) is at the same height as the upper bearing (152). The outlet of the sixth branch channel (174b) opens toward the upper bearing (152). In other words, the sixth branch channel (174b) opens toward the sliding part between the upper bearing (152) and the rotating shaft (130). The seventh branch channel (174c) is at the same height as the pin bearing (157). The outlet of the seventh branch channel (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 lubrication mechanism (170) of Embodiment 2 includes an oil inlet passage (175) for introducing refrigerant oil into the compression mechanism (140). The oil inlet passage (175) includes an oil groove (176), a housing-side passage (177), and a fixed-side passage (178). The oil groove (176) is an annular groove formed around the upper bearing (152). Refrigerant oil that has leaked into the crank chamber (153) flows into the oil groove (176). The housing-side passage (177) is formed in the housing (150), and its inlet end communicates with the oil groove (176). The fixed-side passage (178) is formed in the fixed scroll (141), and its inlet end communicates with the housing-side passage (177). The oil in the fixed channel (178) is supplied to the thrust-direction sliding portion between the fixed scroll (141) and the movable scroll (160).

[0126] (6-3) Operating procedures When the rotating shaft (130) is rotated by the electric motor (125), the upper eccentric part (132) rotates eccentrically, and the movable scroll (160) rotates accordingly. The refrigerant in the suction pipe (123) flows into the inside of the compression mechanism (140) from the suction port (146). The volume of the compression chamber between the movable side wrap (162) and the fixed side wrap (143) gradually decreases, and the refrigerant is compressed in the compression chamber. The compressed refrigerant flows out into the first space (S1). The refrigerant in the first space (S1) flows out into the second space (S2) through the passage (not shown) around the compression mechanism (140). A portion of this refrigerant flows downward through the 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 out into the refrigerant circuit (10) from the discharge pipe (124).

[0127] (6-4) Regarding refrigerants and refrigerant oils The refrigerant and refrigerant oil in Embodiment 2 are basically the same as those in Embodiment 1. In other words, any of the refrigerants and refrigerant oils described in Embodiment 1 can be used in Embodiment 2. In Embodiment 2, the dissolved 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 end plate (121c) of the casing (121). The viscometer can measure the dissolved viscosity of the first refrigerant oil with a value of h1 or less in the oil reservoir (135).

[0128] In Embodiment 2, the refrigerant oil located at or below the height position h1 of the suction port (171a) of the oil supply pump (171) is defined as the first refrigerant oil. In Embodiment 2, the first dissolving viscosity η1, which is the lower limit of the dissolving viscosity of the first refrigerant oil, is 5.0 [mPa·s]. In other words, the dissolving viscosity η of the first refrigerant oil is 5.0 [mPa·s] or greater. This reduces the amount of wear on each sliding part of the scroll compressor (120). The sliding parts referred to here include not only the upper bearing (152), lower bearing (156), and pin bearing (157), but also the thrust sliding part between the fixed scroll (141) and the movable scroll (160). The relationship between the amount of wear and the dissolving viscosity of the refrigerant oil is the same as in Figure 7, so a detailed explanation is omitted.

[0129] In Embodiment 2, the results of investigating the second dissolution viscosity η2, which is the upper limit of the dissolution viscosity of the first refrigerant oil, will be described. Figure 10 shows the results of verifying the relationship between the dissolution viscosity of the refrigerant oil, the displacement volume Vcs of the scroll-type compression mechanism, and the bearing loss ratio γ2. Line segment L4 in Figure 10 represents a compressor with a displacement volume Vcs of 35 cc, line segment L5 represents a compressor with a displacement volume Vcs of 56 cc, and line segment L6 represents a compressor with a displacement volume Vc of 98 cc. Figure 10 shows the relationship between the dissolution viscosity of the refrigerant oil and the bearing loss ratio γ2 in three scroll compressors with different displacement volumes Vcs.

[0130] The displacement volume Vcs is the maximum volume of the compression chamber when the compression mechanism is fully closed. 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, as the displacement volume Vcs increases, the bearing loss ratio γ2 increases. When the displacement volume Vcs of the compression mechanism increases, the size of each bearing increases, and the area of ​​the sliding part increases. Therefore, as the displacement volume Vcs increases, the sliding loss and, consequently, the bearing loss ratio γ2 increase. As can be seen from Figure 10, as the dissolution viscosity of the refrigeration oil increases, the bearing loss ratio γ2 increases. This is because as the dissolution viscosity of the refrigeration oil increases, the sliding loss of the bearings increases.

[0132] Considering the above points, based on the displacement volume Vcs, the dissolution viscosity of the refrigerant oil, and the bearing loss ratio γ2 shown in Figure 10, we obtained a relational equation (2) for the upper limit of the dissolution viscosity (second dissolution viscosity η2) in order to keep the bearing loss ratio γ2 at 10% or less.

[0133] η² = (0.000195 × Vcs + 0.0696) / 0.00714 ... Relational expression (2) Here, Vcs in relation (2) is the displacement volume [cc] of the compression mechanism (140) described above. By making the dissolution viscosity of the refrigerant oil η2 or less, the bearing loss ratio γ2 can be made 10% or less. In other words, when Vcs is within the range shown in Figure 10, it is preferable to make the dissolution viscosity 10 [mPa·s] or less.

[0134] In Embodiment 2, the dissolution viscosity η of the first refrigeration oil is (0.000195 × Vcs + 0.0696) / 0.00714 or less. Therefore, in Embodiment 2, the sliding loss of each bearing (44, 45) of the compression mechanism (140) can be suppressed to 10% or less of the input to the compressor (120). Here, the sliding loss of each bearing (152, 156, 157) accounts for a large proportion of the total mechanical loss of the scroll compressor (120). Therefore, by setting the bearing loss ratio γ2 to 10% or less, the decrease in efficiency of the scroll compressor (120) can be effectively suppressed.

[0135] (7) Other embodiments A rotary compressor may be of the so-called rolling piston type, in which vanes separate from the rollers are in contact with the rollers while the rollers rotate eccentrically. Alternatively, a rotary compressor may be of the so-called hinge vane type, in which the tips of the vanes are rotatably fitted into recesses on the outer surface of the rollers while the rollers rotate eccentrically.

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

[0137] The scroll compressor may be of the asymmetric or symmetric spiral type.

[0138] The air conditioning system (1) may be an indoor multi-type system having multiple indoor units. The air conditioning system (1) may be a movable type that adjusts the temperature of the air in a target space such as a vehicle. The refrigeration cycle system may be a hot water supply system for generating hot water, or a cooling system for generating chilled water. The refrigeration cycle system may be an indoor cooling system for cooling the air inside the storage area. The indoor cooling system may be a stationary type for warehouses, or a movable type for the interior of transport containers or trailers.

[0139] While embodiments and modifications have been described above, it will be understood that a variety of changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the embodiments, modifications, and other embodiments described above may be combined or substituted as appropriate, as long as they do not impair the functions covered by this disclosure.

[0140] The designations "1st," "2nd," "3rd," etc., mentioned above are used to distinguish between the terms to which these designations are attached, and do not limit the number or order of those terms. [Industrial applicability]

[0141] As described above, this disclosure is useful for compressors and refrigeration cycle systems. [Explanation of Symbols]

[0142] 1. Air conditioning system (refrigeration cycle system) 10 Refrigerant Circuit 20,120 Compressors 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 Fueling mechanism 71,171 Fuel pumps 71a, 171a Inlet 72,172 refueling routes A axis center

Claims

1. Electric motor (25,125) and A rotating shaft (30, 130) connected to the aforementioned electric motor (25, 125), The bearings (44, 45, 152, 156, 157) rotatably support the aforementioned rotating shafts (30, 130), A compression mechanism (40, 140) is driven by the aforementioned rotating shafts (30, 130) and compresses the refrigerant, Fueling mechanism (70,170), The device comprises 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 lubrication 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 eccentric portions (32A, 32B, 132) that are eccentric to the axis of the shaft body (31, 131). The aforementioned refueling mechanism (70, 170) is A fuel pump (71, 171) having suction ports (71a, 171a) for drawing in refrigerant oil from oil reservoirs (35, 135) at the bottom of the casing (21, 121), The system includes oil supply passages (72, 172) that supply oil drawn in from the suction ports (71a, 171a) to the sliding parts of the bearings (44, 45, 152, 156, 157) and the sliding parts of the eccentric parts (32A, 32B, 132), The refrigerant is a single refrigerant consisting of a hydrocarbon refrigerant, or a mixed refrigerant containing said hydrocarbon refrigerant. The refrigerant oil is an oil that separates into two layers when the refrigerant pressure is 1.9 [MPa] and the temperature of the refrigerant oil is 75°C. In the oil reservoirs (35, 135), the dissolution viscosity η of the refrigerant oil present at or below the height of the suction ports (71a, 171a) is 5.0 [mPa·s] or greater. Compressor.

2. The compression mechanism is a rotary compression mechanism (40) having an annular cylinder (51A, 51B), annular rollers (52A, 52B) that rotate eccentrically within the cylinder (51A, 51B), and vanes (53A, 53B) for forming a compression chamber within the cylinder (51A, 51B). The compressor according to claim 1.

3. If the displacement volume of the rotary compression mechanism (40) is defined as Vc [cc], The aforementioned dissolution viscosity η is It is less than or equal to (-0.00101 × Vc + 0.12286) / (0.0000146 × Vc + 0.00505). The compressor according to claim 2.

4. The compression mechanism is a scroll-type compression mechanism (140) having a fixed scroll (141) and a movable scroll (160). The compressor according to claim 1.

5. If the displacement volume of the scroll compression mechanism (140) is defined as Vcs [cc], The aforementioned dissolution viscosity η is less than or equal to (0.000195 × Vcs + 0.0696) / 0.00714. The compressor according to claim 4.

6. The refrigeration oil contains one of the following: polyalkylene glycol, polyvinyl ether, or polyol ester. A compressor according to any one of claims 1 to 5.

7. The refrigeration oil contains at least one of the following: an extreme pressure additive of phosphate esters, an antioxidant, and an acid scavenger. A compressor according to any one of claims 1 to 5.

8. The refrigeration oil contains 0.1% by weight or more and 0.5% by weight or less of the antioxidant or acid scavenger. The compressor according to claim 7.

9. The refrigeration oil contains 1.0% by weight or more and 5.0% by weight or less of the extreme pressure additive. The compressor according to claim 7.

10. The molecular weight of the refrigeration oil is 1000 or more and 1800 or less. The compressor according to claim 6.

11. The device comprises a compressor (20,120) according to any one of claims 1 to 5, and a refrigerant circuit (10) through which the hydrocarbon refrigerant circulates to perform a refrigeration cycle. Refrigeration cycle device.

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