Compressor and refrigeration cycle device

Abstract

With respect to a compressor and a refrigeration cycle device that use a refrigerant containing a hydrofluoroolefin, the problem to be solved by the present disclosure is to suppress corrosion of the compressor. A compressor (30) is the compressor (30) of a refrigeration cycle device (20) that uses a refrigerant containing a hydrofluoroolefin and that performs a refrigeration cycle using a refrigerating machine oil containing a polyol ester or a polyvinyl ether. The compressor (30) comprises a sliding section (79s). The sliding section (79s) is formed from an aluminum alloy containing between 5 wt% and 25 wt% silicon. The refrigerating machine oil contains an acid capture agent or an oxygen capture agent and satisfies the following relation. Total content of acid capture agent and oxygen capture agent in refrigerating machine oil [wt%] ≥ (2.3 + 2.6 × (hydrofluoroolefin content in refrigerant [wt%]) − 1.6 × (silicon content in sliding section [wt%])) / 100

Description

Compressor and refrigeration cycle device

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

[0002] BACKGROUND ART Refrigeration cycle devices equipped with a refrigerant circuit that performs a refrigeration cycle have been widely used in air conditioners, water heaters, and the like.

[0003] Patent Document 1 (JP 2010-265777 A) discloses this type of refrigeration cycle device. The refrigerant circuit in Patent Document 1 uses HFO-1234yf or a mixed refrigerant containing HFO-1234yf as one component. This refrigerant does not contain chlorine atoms or bromine atoms, and is known to have little impact on ozone layer depletion.

[0004] However, the refrigerant described in Patent Document 1 has a molecular structure that is relatively unstable against moisture, oxygen, etc., and therefore the refrigerant may deteriorate over a long-term refrigeration cycle, resulting in the generation of impurities, etc. If such impurities are generated, there is a risk that the sliding surfaces of the movable scroll, the bearings, and other sliding parts of the compressor may corrode.

[0005] The present inventors conducted extensive research to inhibit corrosion in the sliding parts of compressors, and as a result discovered that the inhibition of corrosion in sliding parts made of aluminum alloys is related to the amount of hydrofluoroolefin blended in the refrigerant and the amount of silicon contained in the aluminum alloy of the sliding parts. Based on this finding, the present inventors conducted further research and completed the contents of the present disclosure. The present disclosure provides uses of a refrigerant and a refrigeration cycle device according to the following aspects:

[0006] A compressor according to a first aspect is a compressor for a refrigeration cycle device that uses a refrigerant containing a hydrofluoroolefin and a refrigeration oil containing a polyol ester or a polyvinyl ether to perform a refrigeration cycle. The compressor includes a sliding part. The sliding part is made of an aluminum alloy containing 5 wt % to 25 wt % of silicon. The refrigeration oil contains an acid scavenger or an oxygen scavenger and satisfies the following relational expression:

[0007] Total content [wt %] of acid scavenger and oxygen scavenger in refrigerating machine oil ≥ (2.3 + 2.6 × (content [wt %] of hydrofluoroolefin in refrigerant) - 1.6 × (content [wt %] of silicon in sliding parts)) / 100 In the compressor of the first aspect, refrigerating machine oil containing an acid scavenger and an oxygen scavenger that satisfy the above formula is used. Therefore, corrosion of the sliding parts of the compressor due to deterioration of the refrigerant containing hydrofluoroolefin is suppressed.

[0008] A compressor according to a second aspect is the compressor according to the first aspect, wherein the refrigerating machine oil contains an extreme pressure agent.

[0009] A compressor according to a third aspect is the compressor according to the first or second aspect, wherein the refrigerating machine oil contains an antioxidant.

[0010] A refrigeration cycle apparatus according to a fourth aspect includes the compressor according to any one of the first aspect to the third aspect.

[0011] Fig. 1 is a schematic diagram of a refrigeration cycle device according to an embodiment, Fig. 2 is a longitudinal sectional view of a compressor according to an embodiment, and Fig. 3 is a transverse sectional view of a compression mechanism of the compressor according to an embodiment.

[0012] An air conditioner 20 will be described as an example of a refrigeration cycle device.

[0013] (1) Overall Configuration of the Air Conditioning Apparatus As shown in Fig. 1, the air conditioning apparatus 20 of this embodiment includes an outdoor unit 22 and three indoor units 23a, 23b, and 23c. Note that the number of indoor units 23 is merely an example.

[0014] The air conditioner 20 includes a refrigerant circuit 10 that is filled with refrigerant and performs a refrigeration cycle. The refrigerant circuit 10 includes an outdoor circuit 9 housed in an outdoor unit 22, indoor circuits 17a, 17b, and 17c housed in each indoor unit 23, and a liquid-side connecting pipe 18 and a gas-side connecting pipe 19 that connect these indoor circuits 17a, 17b, and 17c to the outdoor circuit 9. These indoor circuits 17a, 17b, and 17c are connected in parallel to each other with respect to the outdoor circuit 9.

[0015] The refrigerant circuit 10 of this embodiment is filled with a refrigerant containing a hydrofluoroolefin. Examples of the hydrofluoroolefin include 2,3,3,3-tetrafluoro-1-propene (hereinafter referred to as "HFO-1234yf"), 1,2,3,3-tetrafluoro-1-propene (hereinafter referred to as "HFO-1234ye"), 1,3,3,3-tetrafluoropropene (hereinafter referred to as "HFO-1234ze"), 3,3,3-trifluoro-1-propene (hereinafter referred to as "HFO-1243zf"), and 1,1,2-trifluoroethylene (hereinafter referred to as "HFO-1243zf"). Examples of refrigerants that can be used include 1,2-difluoroethylene (hereinafter referred to as "HFO-1123"), 1,2-difluoroethylene (hereinafter referred to as "HFO-1132"), 1,1-difluoroethylene (hereinafter referred to as "HFO-1132a"), monofluoroethylene (hereinafter referred to as "HFO-1141"), 1,2,3,3,3-pentafluoro-1-propene (hereinafter referred to as HFO-1225ye), 1,2,2-trifluoro-1-propene, 2-fluoro-1-propene, and mixed refrigerants thereof. 1,2-Difluoroethylene may be trans-1,2-difluoroethylene [(E)-HFO-1132], cis-1,2-difluoroethylene [(Z)-HFO-1132], or a mixture thereof.

[0016] The refrigerant may be a refrigerant containing a hydrofluoroolefin, or may be a refrigerant consisting solely of a hydrofluoroolefin.

[0017] The refrigerant may contain, as a component other than the hydrofluoroolefin, for example, difluoromethane (hereinafter referred to as "HFC-32"), pentafluoroethane (hereinafter referred to as "HFC-125"), 1,1,2,2-tetrafluoroethane (hereinafter referred to as "HFC-134"), 1,1,1,2-tetrafluoroethane (hereinafter referred to as "HFC-134a"), 1,1,1-trifluoroethane (hereinafter referred to as "HFC-143 ... , 1-difluoroethane (hereinafter referred to as "HFC-152a"), HFC-161, HFC-227ea, HFC-236ea, HFC-236fa, HFC-365mfc, methane, ethane, propane, propene, butane, isobutane, pentane, 2-methylbutane, cyclopentane, dimethyl ether, bistrifluoromethyl sulfide, carbon dioxide, and helium may also be a mixed refrigerant blended with at least one of these.

[0018] For example, a mixed refrigerant consisting of two components, HFO-1234yf and HFC-32, may be used as the refrigerant. In this case, from the viewpoint of performance when used in a refrigeration cycle device, the mixed refrigerant of HFO-1234yf and HFC-32 preferably contains 30 wt % or more and 80 wt % or less of HFO-1234yf and 20 wt % or less of HFC-32.

[0019] Alternatively, a mixed refrigerant of HFO-1234yf and HFC-125 may be used. In this case, the proportion of HFC-125 is preferably 10 wt % or more, and more preferably 10 wt % to 20 wt %.

[0020] Alternatively, a mixed refrigerant consisting of three components, HFO-1234yf, HFC-32, and HFC-125, may be used.

[0021] (2) Outdoor Circuit The outdoor circuit 9 is provided with a compressor 30, an outdoor heat exchanger 11, an outdoor expansion valve 12, and a four-way switching valve 13.

[0022] The compressor 30 is configured as, for example, an inverter-type compressor with a variable operating capacity. Electric power is supplied to the compressor 30 via an inverter. The discharge side of the compressor 30 is connected to the second port P2 of the four-way selector valve 13, and the suction side of the compressor 30 is connected to the first port P1 of the four-way selector valve 13. Details of the compressor 30 will be described later.

[0023] The outdoor heat exchanger 11 is configured as a cross-fin type fin-and-tube heat exchanger. An outdoor fan 14 is provided near the outdoor heat exchanger 11. In the outdoor heat exchanger 11, heat exchange occurs between outdoor air and refrigerant. One end of the outdoor heat exchanger 11 is connected to a third port P3 of the four-way switching valve 13, and the other end is connected to the outdoor expansion valve 12. In addition, a fourth port P4 of the four-way switching valve 13 is connected to the gas-side connecting pipe 19.

[0024] The outdoor expansion valve 12 is provided between the outdoor heat exchanger 11 and the liquid side end of the outdoor circuit 9. The outdoor expansion valve 12 is configured as an electronic expansion valve with a variable opening.

[0025] The four-way switching valve 13 is configured to be freely switchable between a first state in which the first port P1 and the fourth port P4 are connected and the second port P2 and the third port P3 are connected, i.e., the state shown by the solid lines in FIG. 1, and a second state in which the first port P1 and the third port P3 are connected and the second port P2 and the fourth port P4 are connected, i.e., the state shown by the dashed lines in FIG. 1.

[0026] (3) Indoor Circuits Each of the indoor circuits 17a, 17b, and 17c is provided with an indoor heat exchanger 15a, 15b, or 15c and an indoor expansion valve 16a, 16b, or 16c in this order from the gas side end to the liquid side end.

[0027] The indoor heat exchangers 15a, 15b, and 15c are configured as cross-fin type fin-and-tube heat exchangers. Indoor fans 21a, 21b, and 21c are provided near the indoor heat exchangers 15a, 15b, and 15c. In the indoor heat exchanger 15, heat is exchanged between the indoor air and the refrigerant. The indoor expansion valves 16a, 16b, and 16c are configured as electronic expansion valves with variable opening.

[0028] (4) Compressor Configuration The compressor 30 is configured as, for example, a hermetic high-pressure dome-type scroll compressor. The configuration of the compressor 30 will be described with reference to FIGS. 2 and 3.

[0029] The compressor 30 includes a casing 70 that forms a vertical sealed container. Inside the casing 70, an electric motor 85 and a compression mechanism 82 are arranged from bottom to top.

[0030] The electric motor 85 includes a stator 83 and a rotor 84. The stator 83 is fixed to the body of the casing 70. On the other hand, the rotor 84 is disposed inside the stator 83, and is connected to a crankshaft 90.

[0031] The compression mechanism 82 includes a movable scroll 76 and a fixed scroll 75, constituting a scroll-type compression mechanism. The movable scroll 76 includes a substantially disk-shaped movable end plate 76b and a spiral-shaped movable lap 76a. The movable lap 76a is erected on the front surface, i.e., the upper surface, of the movable end plate 76b. A cylindrical protrusion 76c, into which an eccentric portion of the crankshaft 90 is inserted, is erected on the back surface, i.e., the lower surface, of the movable end plate 76b. The movable scroll 76 is supported by a housing 77 disposed below the movable scroll 76 via an Oldham ring 79. The fixed scroll 75 includes a substantially disk-shaped fixed end plate 75b and a spiral-shaped fixed lap 75a. The fixed lap 75a is erected on the front surface, i.e., the lower surface, of the fixed end plate 75b. In the compression mechanism 82, the fixed wrap 75a and the movable wrap 76a are meshed with each other, thereby forming a plurality of compression chambers 73 between the contact portions of the two wraps 75a, 76a.

[0032] The compressor 30 of this embodiment employs a so-called asymmetric spiral structure, in which the number of turns, i.e., the spiral length, is different between the fixed-side wrap 75a and the movable-side wrap 76a. The plurality of compression chambers 73 are each composed of a first compression chamber 73a defined between the inner circumferential surface of the fixed-side wrap 75a and the outer circumferential surface of the movable-side wrap 76a, and a second compression chamber 73b defined between the outer circumferential surface of the fixed-side wrap 75a and the inner circumferential surface of the movable-side wrap 76a.

[0033] In the compression mechanism 82, a suction port 98 is formed in the outer edge of the fixed scroll 75. A suction pipe 57 that penetrates the top of the casing 70 is connected to the suction port 98. The suction port 98 intermittently communicates with each of the first compression chamber 73 a and the second compression chamber 73 b as the movable scroll 76 revolves. The suction port 98 is also provided with a suction check valve (not shown) that prohibits the flow of refrigerant from the compression chamber 73 back to the suction pipe 57.

[0034] Furthermore, in the compression mechanism 82, a discharge port 93 is formed in the center of the fixed-side end plate 75b. The discharge port 93 intermittently communicates with each of the first compression chamber 73a and the second compression chamber 73b as the movable scroll 76 revolves. The discharge port 93 opens into a muffler space 96 formed above the fixed scroll 75.

[0035] The interior of the casing 70 is divided by the disk-shaped housing 77 into an upper suction space 101 and a lower discharge space 100. The suction space 101 communicates with the suction port 98 through a communication port (not shown). The discharge space 100 communicates with the muffler space 96 through a communication passage 103 formed between the fixed scroll 75 and the housing 77. During operation, refrigerant discharged from the discharge port 93 flows into the discharge space 100 through the muffler space 96, making it a high-pressure space filled with refrigerant compressed by the compression mechanism 82. The discharge space 100 is opened by the discharge pipe 56 that penetrates the body of the casing 70.

[0036] In this embodiment, the casing 70 of the compressor 30 contains components made of organic materials, such as the insulating coating material for the windings of the stator 83, the insulating film, and the sealing material for the compression mechanism 82. These components are made of substances that are not physically or chemically altered by the refrigerant even when they come into contact with the high-temperature, high-pressure refrigerant, and are particularly solvent-resistant, extraction-resistant, thermally and chemically stable, and foam-resistant.

[0037] Specifically, the insulating coating material for the windings of the stator 83 is one of polyvinyl formal, polyester, THEIC-modified polyester, polyamide, polyamide-imide, polyester-imide, and polyester-amide-imide. A double-coated wire with an upper layer of polyamide-imide and a lower layer of polyester-imide is preferred. In addition to the above materials, an enamel coating with a glass transition temperature of 120°C or higher may also be used.

[0038] The insulating film is made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), or polybutylene terephthalate (PBT). It is also possible to use a foamed film made of the same foam material as the refrigerant in the refrigeration cycle. The insulating material used to hold the windings of the insulators is made of either polyether ether ketone (PEEK) or liquid crystal polymer (LCP). Epoxy resin is used for the varnish. The sealing material used is either polytetrafluoroethylene, packing made of aramid fiber or NBR, perfluoroelastomer, silicone rubber, hydrogenated NBR rubber, or fluororubber.

[0039] An oil sump for storing refrigeration oil is formed at the bottom of casing 70. A first oil feed passage 104 that opens into the oil sump is formed inside crankshaft 90. A second oil feed passage 105 that connects to first oil feed passage 104 is formed in movable-side end plate 76b. In compressor 30, refrigeration oil in the oil sump is supplied to low-pressure compression chamber 73 through first oil feed passage 104 and second oil feed passage 105.

[0040] As described above, the Oldham ring 79 is provided between the movable scroll 76 and the housing 77. The Oldham ring 79 constitutes a rotation prevention mechanism for preventing rotation of the movable scroll 76. The Oldham ring 79 is formed in a ring shape, and scroll keys are respectively provided on the upper side of the ring at positions facing each other. In addition, a pair of housing keys are provided on the lower side of the Oldham ring 79 at positions 90 degrees offset from the scroll keys in the circumferential direction. In other words, the Oldham ring 79 has scroll keys and housing keys alternately provided at positions 90 degrees offset from each other in the circumferential direction of the ring.

[0041] A first guide groove extending radially is formed on the back surface of the movable end plate 76b of the movable scroll 76 to correspond to the scroll key of the Oldham ring 79. Furthermore, a second guide groove extending radially is formed on the upper surface of the housing 77 to correspond to the housing key of the Oldham ring 79. The Oldham ring 79 is configured so that the scroll key slides in the first guide groove and the housing key slides in the second guide groove. As a result, when the crankshaft 90 rotates, the Oldham ring 79 prevents the movable scroll 76 from rotating on its own axis, and only allows it to revolve, i.e., rotate. Thus, the Oldham ring 79 has a sliding surface that slides against the movable scroll 76 and a sliding surface that slides against the housing 77.

[0042] The Oldham ring 79 of this embodiment is entirely made of a silicon-containing aluminum alloy known as a high-silicon aluminum material. The aluminum alloy constituting the Oldham ring 79 has a silicon content of 5 wt % or more and 25 wt % or less. The Oldham ring 79 is disposed so as to be in contact with the refrigerant and refrigeration oil, and the sliding portion 79 s, which is the portion that slides against the movable scroll 76 and the housing 77, is made of an aluminum alloy containing 5 wt % or more and 25 wt % or less of silicon. The Oldham ring 79 may be formed with the aluminum alloy separately only on the outer surface, i.e., the sliding portion 79 s. A preferred lower limit of the silicon content of the aluminum alloy of the sliding portion 79 s is, for example, 7 wt %. To avoid the use of expensive aluminum alloys with high silicon content, a preferred upper limit of the silicon content of the aluminum alloy of the sliding portion 79 s is 20 wt %, and more preferably 18 wt %.

[0043] (5) Regarding Refrigerating Machine Oil In this embodiment, refrigerating machine oil containing at least one of two types of base oil, polyol ester and polyvinyl ether, as a main component is used in the compressor 30. For example, the refrigerating machine oil used in this embodiment contains polyvinyl ether as a main component of the two types of base oil. Note that the main component here means the component that accounts for the largest weight percentage of the refrigerating machine oil.

[0044] The refrigerating machine oil used in this embodiment is composed primarily of a polyvinyl ether having a structural unit represented by the following general formula I. Among polyvinyl ethers, polyvinyl ethers with this structure have excellent compatibility with refrigerants having one double bond in the molecular structure.

[0045]

[0046] In general formula I, R1, R2, and R3 represent hydrogen or a hydrocarbon group having 1 to 8 carbon atoms. R1, R2, and R3 may be the same or different from one another. Furthermore, in general formula I, for each structural unit, R4 has a structural ratio of 40% to 100% alkyl groups having 1 or 2 carbon atoms and 0% to 60% alkyl groups having 3 or 4 carbon atoms.

[0047] The refrigerating machine oil has a kinematic viscosity of 30 cSt or more and 400 cSt or less at 40°C, a pour point of -30°C or less, a surface tension of 0.02 N / m or more and 0.04 N / m or less at 20°C, and a density of 0.8 g / cm at 15°C. 3 1.8g / cm or more 3 The refrigerating machine oil has a saturated moisture content of 2000 ppm or more at a temperature of 30°C and a relative humidity of 90%, and an aniline point within a predetermined range. Here, the "aniline point" is a numerical value that indicates the solubility of, for example, hydrocarbon solvents, and represents the temperature at which, when a sample (here, refrigerating machine oil) is mixed with an equal volume of aniline and cooled, the two become insoluble and begin to become cloudy (as defined in detail in JIS K 2256). Note that these values ​​are those of the refrigerating machine oil itself in a state in which the refrigerant is not dissolved. This also applies to the refrigerating machine oils described in the other embodiments.

[0048] In this embodiment, polyvinyl ether, which is the main component of the refrigerating machine oil, is compatible with the hydrofluoroolefin refrigerant. The kinetic viscosity of the refrigerating machine oil is 400 cSt or less at 40°C. Therefore, the hydrofluoroolefin refrigerant dissolves to a certain extent in the refrigerating machine oil. Furthermore, because the pour point of the refrigerating machine oil is −30°C or less, the fluidity of the refrigerating machine oil can be ensured even in relatively low-temperature areas of the refrigerant circuit 10. Furthermore, because the surface tension is 0.04 N / m or less at 20°C, the refrigerating machine oil discharged from the compressor 30 is less likely to form large oil droplets that would be difficult to be swept away by the refrigerant. Therefore, the refrigerating machine oil discharged from the compressor 30 dissolves in the refrigerant and returns to the compressor 30 together with the refrigerant.

[0049] Furthermore, since the kinematic viscosity of the refrigerating machine oil is 30 cSt or more at 40°C, the kinetic viscosity is not too low, resulting in insufficient oil film strength, and lubrication performance is ensured. Furthermore, since the surface tension is 0.02 N / m or more at 20°C, the refrigerating machine oil is less likely to break down into small oil droplets in the gas refrigerant inside the compressor 30, and a large amount of refrigerating machine oil is not discharged from the compressor 30. Therefore, a sufficient amount of refrigerating machine oil can be stored in the compressor 30.

[0050] Furthermore, since the saturated moisture content of the refrigerating machine oil is 2000 ppm or more at a temperature of 30°C and a relative humidity of 90%, the hygroscopicity of the refrigerating machine oil is relatively high. This allows the refrigerating machine oil to capture a certain amount of moisture in the refrigerant. Hydrofluoroolefins have a molecular structure that is easily altered or deteriorated by the influence of the moisture contained therein. Therefore, the moisture absorption effect of the refrigerating machine oil can suppress such deterioration.

[0051] Furthermore, by setting the aniline point of the refrigeration oil to a value within a predetermined range, the compatibility between the refrigeration oil and predetermined resin functional parts (functional parts made of organic materials arranged so as to be able to come into contact with the refrigeration oil or refrigerant, such as sliding members and sealing members) is improved. In other words, by setting the aniline point to a value within the predetermined range, it is possible to prevent the resin functional parts from swelling or shrinking due to the influence of the refrigeration oil, and to avoid impairing the functions of the resin functional parts.

[0052] The refrigerating machine oil of this embodiment contains an acid scavenger or an oxygen scavenger as an additive, and may further contain an extreme pressure agent, an antioxidant, an antifoaming agent, an oiliness agent, and a copper deactivator as needed. The blending amounts of each additive other than the acid scavenger and the oxygen scavenger are preferably set so that the proportion of each additive in the refrigerating machine oil is 0.01 wt % or more and 5 wt % or less.

[0053] The total amount of the acid scavenger and the oxygen scavenger satisfies the following relational expression: However, as described above, only one of the acid scavenger and the oxygen scavenger may be blended.

[0054] Total content of acid scavenger and oxygen scavenger in refrigerating machine oil [wt %]≧(2.3+2.6×(hydrofluoroolefin content in refrigerant [wt %])−1.6×(silicon content in sliding part [wt %])) / 100 The above relational expression was obtained by the following method. A plurality of aluminum alloys with different silicon contents were prepared and used as rings for thrust sliding tests. Using each ring, thrust sliding tests were performed by changing the hydrofluoroolefin content and the total amount of acid scavenger and oxygen scavenger blended into the refrigerating machine oil. The test conditions were a speed of 5 cm / sec. In the thrust sliding test, combinations of the hydrofluoroolefin content just before the ring seized and the total amount of acid scavenger and oxygen scavenger were plotted for each ring, and a regression line was obtained. The equation of this regression line was used as the above relational expression.

[0055] F1 is defined as: F1 = (2.3 + 2.6 × (hydrofluoroolefin content in refrigerant [wt %]) - 1.6 × (silicon content in sliding part [wt %])) / 100. F1 is an index showing the amount of acid in the refrigerant that can be captured by the acid scavenger and oxygen scavenger.

[0056] If the total content of the acid scavenger and oxygen scavenger in the refrigeration oil is less than F1, the acid scavenger and oxygen scavenger will not be able to sufficiently capture the acid, and the uncaptured acid will likely corrode the aluminum parts.

[0057] If the total content of the acid scavenger and oxygen scavenger in the refrigerating machine oil is F1 or more, the acid scavenger and oxygen scavenger will be able to sufficiently trap acid, thereby suppressing corrosion of aluminum parts.

[0058] When the refrigerant is composed only of one or more types of hydrofluoroolefins, the total amount of the acid scavenger and the oxygen scavenger is, for example, preferably more than 3.0 wt %, and more preferably more than 3.2 wt %.

[0059] The upper limit of the total amount of the acid scavenger and the oxygen scavenger is, for example, 10.0 wt%. If the total amount of the acid scavenger and the oxygen scavenger exceeds 10.0 wt%, the viscosity of the refrigerating machine oil decreases. As a result, lubricity decreases and wear is more likely to occur. From the viewpoint of suppressing a decrease in the viscosity of the refrigerating machine oil, the upper limit of the total content of the acid scavenger and the oxygen scavenger in the refrigerating machine oil is, for example, preferably "F1 + 5.0 wt%", and more preferably "F1 + 2.0 wt%".

[0060] Examples of acid scavengers that can be used include epoxy compounds such as phenyl glycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, α-olefin oxide, and epoxidized soybean oil. Among these, preferred acid scavengers from the viewpoint of compatibility with the refrigerant are phenyl glycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, and α-olefin oxide. The alkyl group of the alkyl glycidyl ether and the alkylene group of the alkylene glycol glycidyl ether may be branched. The number of carbon atoms in these may be from 3 to 30, more preferably from 4 to 24, and even more preferably from 6 to 16. The total number of carbon atoms in the α-olefin oxide may be from 4 to 50, more preferably from 4 to 24, and even more preferably from 6 to 16. Only one type of acid scavengers may be used, or multiple types may be used in combination.

[0061] Examples of oxygen scavengers that can be used include sulfur-containing aromatic compounds such as 4,4'-thiobis(3-methyl-6-tert-butylphenol), diphenyl sulfide, dioctyldiphenyl sulfide, dialkyldiphenylene sulfide, benzothiophene, dibenzothiophene, phenothiazine, benzothiapyran, thiapyran, thianthrene, dibenzothiapyran, and diphenylene disulfide, various olefins, aliphatic unsaturated compounds such as dienes and trienes, and terpenes having double bonds. Only one type of oxygen scavenger may be used, or multiple types may be used in combination.

[0062] The extreme pressure agent may contain a phosphate ester. Examples of the phosphate ester include phosphate ester, phosphite ester, acid phosphate ester, and acid phosphite ester. The extreme pressure agent may contain an amine salt of a phosphate ester, phosphite ester, acid phosphate ester, or acid phosphite ester.

[0063] It is also possible to add extreme pressure agents other than those mentioned above. For example, organic sulfur compound-based extreme pressure agents such as monosulfides, polysulfides, sulfoxides, sulfones, thiosulfinates, sulfurized oils and fats, thiocarbonates, thiophenes, thiazoles, and methanesulfonate esters; thiophosphate ester-based extreme pressure agents such as thiophosphate triesters; ester-based extreme pressure agents such as higher fatty acids, hydroxyaryl fatty acids, polyhydric alcohol esters, and acrylic esters; organic chlorine-based extreme pressure agents such as chlorinated hydrocarbons and chlorinated carboxylic acid derivatives; organic fluorinated extreme pressure agents such as fluorinated aliphatic carboxylic acids, fluorinated ethylene resins, fluorinated alkylpolysiloxanes, and fluorinated graphite; alcohol-based extreme pressure agents such as higher alcohols; and metal compound-based extreme pressure agents such as naphthenates (e.g., lead naphthenate), fatty acid salts (e.g., lead fatty acid), thiophosphates (e.g., zinc dialkyldithiophosphate), thiocarbamates, organic molybdenum compounds, organic tin compounds, organic germanium compounds, and borate esters.

[0064] Furthermore, phenol-based antioxidants and amine-based antioxidants can be used as the antioxidant. Phenol-based antioxidants include 2,6-di-tert-butyl-4-methylphenol (DBPC), 2,6-di-tert-butyl-4-ethylphenol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,4-dimethyl-6-tert-butylphenol, and 2,6-di-tert-butylphenol. Amine-based antioxidants include N,N'-diisopropyl-p-phenylenediamine, N,N'-di-sec-butyl-p-phenylenediamine, phenyl-α-naphthylamine, and N,N'-diphenyl-p-phenylenediamine. Note that oxygen scavengers that capture oxygen can also be used as antioxidants.

[0065] In addition, benzotriazole and its derivatives can be used as copper deactivators, silicon compounds can be used as antifoaming agents, and higher alcohols can be used as oily agents.

[0066] Furthermore, the refrigerating machine oil of this embodiment can also contain, as necessary, load-bearing additives, chlorine scavengers, detergent-dispersants, viscosity index improvers, rust inhibitors, stabilizers, corrosion inhibitors, pour point depressants, etc. The blending amount of each additive in the refrigerating machine oil may be from 0.01 wt% to 5 wt%, and preferably from 0.05 wt% to 3 wt%. The refrigerating machine oil of this embodiment also has a chlorine concentration of 50 ppm or less and a sulfur concentration of 50 ppm or less.

[0067] (6) Overall Operation A description will be given of the operation of the air conditioner 20. The air conditioner 20 is capable of performing cooling operation and heating operation, and the four-way switching valve 13 switches between the cooling operation and the heating operation.

[0068] (6-1) Cooling Operation During cooling operation, the four-way switching valve 13 is set to the first state. When the compressor 30 is operated in this state, the high-pressure refrigerant discharged from the compressor 30 condenses in the outdoor heat exchanger 11 by dissipating heat to the outdoor air. The refrigerant condensed in the outdoor heat exchanger 11 is distributed to each indoor circuit 17. In each indoor circuit 17, the incoming refrigerant is decompressed by the indoor expansion valve 16, and then absorbs heat from the indoor air in the indoor heat exchanger 15 to evaporate. Meanwhile, the indoor air is cooled and supplied to the room.

[0069] The refrigerant evaporated in each indoor circuit 17 is combined with the refrigerant evaporated in the other indoor circuits 17 and returns to the outdoor circuit 9. In the outdoor circuit 9, the refrigerant returned from each indoor circuit 17 is compressed again by the compressor 30 and discharged. During cooling operation, the opening of each indoor expansion valve 16 is superheat controlled so that the superheat of the refrigerant at the outlet of the indoor heat exchanger 15 is a constant value. The constant value of the superheat of the refrigerant at the outlet of the indoor heat exchanger 15 is, for example, 5°C.

[0070] (6-2) Heating Operation During heating operation, the four-way selector valve 13 is set to the second state. When the compressor 30 is operated in this state, the high-pressure refrigerant discharged from the compressor 30 is distributed to each indoor circuit 17. In each indoor circuit 17, the refrigerant that has flowed in transfers heat to the indoor air in the indoor heat exchanger 15 and condenses. Meanwhile, the indoor air is heated and supplied to the room. The refrigerant condensed in the indoor heat exchanger 15 joins together in the outdoor circuit 9.

[0071] The refrigerant that joins in the outdoor circuit 9 is decompressed by the outdoor expansion valve 12, and then evaporates by absorbing heat from the outdoor air in the outdoor heat exchanger 11. The refrigerant that evaporated in the outdoor heat exchanger 11 is compressed again by the compressor 30 and discharged. During heating operation, the opening of each indoor expansion valve 16 is subcooled so that the degree of subcooling of the refrigerant at the outlet of the indoor heat exchanger 15 is kept at a constant value. The constant value of the degree of subcooling of the refrigerant at the outlet of the indoor heat exchanger 15 is, for example, 5°C.

[0072] (7) Features (7-1) As described above, refrigerants containing hydrofluoroolefins such as HFO-1234yf have a molecular structure that is relatively unstable against moisture, oxygen, and the like. Therefore, the refrigerant may deteriorate over a long-term refrigeration cycle, resulting in the generation of strong acids such as hydrofluoric acid and trifluoroacetic acid. When such strong acids are generated, the sliding parts of the compressor 30 may be physically or chemically altered, resulting in deterioration or wear. As a result, abnormal wear tends to occur in the sliding parts of the compressor 30.

[0073] It is also conceivable to suppress corrosion by increasing the Si content of aluminum parts used in the sliding parts of the compressor 30. However, aluminum alloys with a high Si content require special technology and are expensive.

[0074] In this embodiment, the total amount of the acid scavenger and the oxygen scavenger satisfies the following relational expression.

[0075] The total content [wt %] of acid scavenger and oxygen scavenger in refrigerating machine oil is defined as follows: ≧(2.3+2.6×(hydrofluoroolefin content [wt %] in refrigerant)−1.6×(silicon content [wt %] in sliding parts)) / 100 F1=(2.3+2.6×(hydrofluoroolefin content [wt %] in refrigerant)−1.6×(silicon content [wt %] in sliding parts)) / 100. If the total content of acid scavenger and oxygen scavenger in refrigerating machine oil is F1 or more, the acid scavenger and oxygen scavenger can sufficiently capture the acid in the refrigerant. This can suppress corrosion of aluminum parts. As a result, the occurrence of abnormal wear of aluminum parts can be suppressed.

[0076] (7-2) In this embodiment, the refrigeration oil contains an extreme pressure agent, which further suppresses corrosion of aluminum parts.

[0077] (7-3) In this embodiment, the refrigeration oil contains an antioxidant, which further suppresses corrosion of aluminum parts.

[0078] (8) Other Embodiments The above embodiment may be configured as follows.

[0079] (8-1) Other Embodiment A In the above embodiment, the sliding portion 79 s of the Oldham ring 79 of the compression mechanism 82 is made of an aluminum alloy containing 5 wt % or more and 25 wt % or less of silicon, but this aluminum alloy may also be applied to other sliding portions of the compression mechanism 82.

[0080] Specifically, the aluminum alloy may be applied to the sliding portion of the movable scroll 76, the sliding portion of the crankshaft 90 against bearings such as journal bearings and thrust bearings, and the sliding portion of bearings such as journal bearings and thrust bearings against the crankshaft 90.

[0081] Examples of the sliding parts of the movable scroll 76 include the part of the protruding part 76c that slides against the eccentric part of the crankshaft 90, the part of the movable side wrap 76a that slides against the fixed side wrap 75a of the fixed scroll 75, and the part of the movable side end plate 76b that slides against the Oldham ring 79.

[0082] The entire member having a sliding portion may be made of the aluminum alloy, or only the sliding portion exposed on the sliding surface may be made of the aluminum alloy.

[0083] (8-2) Alternative Embodiment B In the above-described embodiment, the compression mechanism 82 of the compressor 30 is configured as a scroll-type compression mechanism. However, the compression mechanism 82 may be a compression mechanism of other types, such as a swing-type, rotary-type, or screw-type. In such other types, the above-described aluminum alloy may also be applied to predetermined sliding parts of the compression mechanism.

[0084] (8-3) Other Embodiment C In the above embodiment, a refrigerating machine oil containing polyvinyl ether as a main component out of two types of base oil, polyol ester and polyvinyl ether, is used as an example. However, a refrigerating machine oil containing polyol ester as a main component may also be used.

[0085] As the polyol ester, for example, it is preferable to use any one of or a mixture of "esters of aliphatic polyhydric alcohols and linear or branched fatty acids," "partial esters of aliphatic polyhydric alcohols and linear or branched fatty acids," and "complex esters of partial esters of aliphatic polyhydric alcohols and linear or branched fatty acids having 3 to 9 carbon atoms, and aliphatic dibasic acids or aromatic dibasic acids." Among polyol esters, these polyol esters have excellent compatibility with hydrofluoroolefin refrigerants.

[0086] Examples of aliphatic polyhydric alcohols that form "esters or partial esters of aliphatic polyhydric alcohols and linear or branched fatty acids" include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, trimethylolethane, ditrimethylolethane, trimethylolpropane, ditrimethylolpropane, glycerin, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, etc. Of these, pentaerythritol, dipentaerythritol, and tripentaerythritol are preferred as aliphatic polyhydric alcohols.

[0087] Furthermore, fatty acids having 3 to 12 carbon atoms can be used, such as propionic acid, butyric acid, pivalic acid, valeric acid, caproic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, isovaleric acid, neopentanoic acid, 2-methylbutyric acid, 2-ethylbutyric acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2-dimethyloctanoic acid, 2-butyloctanoic acid, and 3,5,5-trimethylhexanoic acid. Fatty acids having 5 to 12 carbon atoms are preferred, with fatty acids having 5 to 9 carbon atoms being more preferred. Specifically, valeric acid, hexanoic acid, heptanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2-dimethyloctanoic acid, 2-butyloctanoic acid, and 3,5,5-trimethylhexanoic acid are preferred.

[0088] Furthermore, in the "complex ester of a partial ester of an aliphatic polyhydric alcohol and a linear or branched fatty acid having from 3 to 9 carbon atoms, and an aliphatic dibasic acid or an aromatic dibasic acid," fatty acids having from 5 to 7 carbon atoms are preferred, and fatty acids having 5 or 6 carbon atoms are more preferred. Specifically, valeric acid, hexanoic acid, isovaleric acid, 2-methylbutyric acid, 2-ethylbutyric acid, or mixtures thereof are preferred. Furthermore, a fatty acid in which a fatty acid having 5 carbon atoms and a fatty acid having 6 carbon atoms are mixed in a weight ratio of from 10:90 to 90:10 can be used.

[0089] Aliphatic dibasic acids include succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, and docosanedioic acid. Aromatic dibasic acids include phthalic acid and isophthalic acid. The esterification reaction for preparing a complex ester involves reacting a polyhydric alcohol and a dibasic acid in a predetermined ratio to effect partial esterification, and then reacting the resulting partial ester with a fatty acid. The order of the reaction of the dibasic acid and the fatty acid may be reversed, or the dibasic acid and the fatty acid may be mixed and subjected to esterification.

[0090] The refrigerating machine oil may also contain polyalkylene glycol. From the viewpoint of good compatibility with hydrofluoroolefin refrigerants, the polyalkylene glycol may be a polyalkylene glycol having the molecular formula: R1(R2) m (R3O) n A polyalkylene glycol having a molecular structure represented by R4 (where m and n are integers, R1 and R4 represent hydrogen, an alkyl group having 1 to 6 carbon atoms, or an aryl group, and R2 and R3 represent an alkyl group having 1 to 4 carbon atoms) is preferred.

[0091] (8-4) Alternative Embodiment D In the above-described embodiment, the refrigerant circuit 10 may be provided with a dryer filled with silicic acid or synthetic zeolite as a desiccant.

[0092] (8-5) Other Embodiment E In addition, in the above-described embodiment, the refrigeration cycle device 20 may be an air conditioner dedicated to heating, a refrigerator or freezer for cooling food, a refrigeration cycle device combining an air conditioner with a refrigerator or freezer, or a hot water supply device that heats water using a radiator in the refrigerant circuit 10.

[0093] It should be noted that the above-described embodiments are essentially preferred examples and are not intended to limit the scope of the present disclosure, its applications, or its uses.

[0094] The present disclosure will be described below based on examples, but the present disclosure is not limited to those described in the following examples.

[0095] Test results of the refrigeration oil used in the compressor and the refrigeration cycle device of this embodiment will be described. In the test of the refrigeration oil, a thrust sliding test was carried out using the test pieces shown in Table 1 to analyze the influence of the refrigeration oil on the compressor and the refrigeration cycle device.

[0096]

[0097] The refrigerating machine oil used was a mixture of polyvinyl ether and an acid scavenger and an oxygen scavenger in the amounts shown in Table 1.

[0098] In the tests, the type and amount of refrigerant, the silicon content in the aluminum alloy of the test specimen, and the total amount of acid scavenger and oxygen scavenger blended into the refrigerant oil were changed. Refrigerant oil was applied to the disk, and a thrust sliding test was conducted. The test conditions were a speed of 5 cm / sec. The surface pressure (MPa) at which the ring seized during the thrust sliding test (hereinafter referred to as the seizure surface pressure) was measured and compared with the seizure surface pressure of the current product. The test results are shown in Table 1.

[0099] As can be seen from Table 1, in Examples 1 to 6 where the total amount of acid scavenger and oxygen scavenger was equal to or greater than the total amount of acid scavenger and oxygen scavenger calculated from the relational expression, the seizure surface pressure was higher than that of the current product.

[0100] In Comparative Examples 2 to 6, in which the total amount of acid scavenger and oxygen scavenger blended was less than the total amount of acid scavenger and oxygen scavenger blended calculated from the relational expression, the seizure surface pressure was lower than that of the current product. Note that Comparative Example 1 does not use a refrigerant containing hydrofluoroolefin.

[0101] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims.

[0102] INDUSTRIAL APPLICABILITY As described above, the present disclosure is useful for a refrigeration cycle device and a compressor that perform a refrigeration cycle.

[0103] 10 Refrigerant circuit 20 Air conditioner (refrigeration cycle device) 30 Compressor 73 Compression chamber 75 Fixed scroll 76 Orbiting scroll 79 Oldham ring 79s Sliding portion 82 Compression mechanism

[0104] JP 2010-265777 A

Claims

1. A compressor (30) in a refrigeration cycle device (20) that uses a refrigerant containing a hydrofluoroolefin and a refrigeration oil containing a polyol ester or a polyvinyl ether to perform a refrigeration cycle, the compressor having a sliding part (79s) made of an aluminum alloy containing 5 wt % to 25 wt % of silicon, the refrigeration oil containing an acid scavenger or an oxygen scavenger, and satisfying the following relational expression: Total content [wt %] of the acid scavenger and the oxygen scavenger in the refrigeration oil ≥ (2.3 + 2.6 × (content [wt %] of hydrofluoroolefin in the refrigerant) - 1.6 × (content [wt %] of silicon in the sliding part)) / 100 2. The compressor according to claim 1, wherein the refrigeration oil contains an extreme pressure agent.

3. The compressor according to claim 1 or 2, wherein the refrigeration oil contains an antioxidant.

4. A refrigeration cycle device (20) comprising the compressor (30) according to any one of claims 1 to 3.

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