JP7618866B1 - Refrigeration oil and refrigeration equipment - Google Patents

Abstract

An object of the present invention is to achieve, in a refrigeration oil and a refrigeration device, both suppression of viscous resistance loss during compressor startup (room temperature) and improvement of oil film load capacity during operation (high temperature).
[Solution] The refrigeration oil disclosed herein is for use in a refrigeration unit in which propane is sealed as a refrigerant, and includes an ester-based base oil having a viscosity grade of ISO VG32 or lower, and a viscosity index improver including a polymethacrylic acid ester having an alkyl substituent having 1 to 18 carbon atoms, and the concentration of the polymethacrylic acid ester is 0.6 wt% or more and 6 wt% or less.
[Selected figure] Figure 7

Description

This disclosure relates to refrigeration oil and refrigeration equipment.

A refrigeration system is composed of at least a compressor, a condenser, an expansion valve, and an evaporator. In a refrigeration system, each component is connected in a closed circuit by refrigerant piping, and a mixture of refrigerant and refrigeration oil circulates within the sealed system.

When a new refrigerant is adopted, a compressor compatible with the new refrigerant must be developed. In compressor development, there is an urgent need to reduce wear loss and improve wear resistance in sliding parts, and there is a demand to select refrigeration oil and oil additives suitable for each refrigerant.

Patent Document 1 discloses an invention that suppresses wear of sliding parts even when the oil film load capacity is reduced due to high temperatures by adding an anti-wear agent (TBP) to refrigeration oil.

JP 2020-158566 A

R290 is a natural refrigerant with a very low GWP. On the other hand, R290 is highly soluble in refrigeration oil. Therefore, in refrigeration equipment that uses R290 as a refrigerant, there is concern that abnormal wear of sliding parts may occur due to a decrease in the viscosity of the refrigeration oil.

To prevent this, the viscosity grade of the base oil used in the refrigeration oil can be increased. However, increasing the viscosity grade of the base oil increases the kinetic viscosity of the refrigeration oil when the refrigeration equipment compressor starts up, which creates the problem of increased friction loss due to viscous resistance.

When using R290 as the refrigerant, there is concern that simply adding the anti-wear agent described in Patent Document 1 to the refrigeration oil may not provide sufficient anti-wear effect.

This disclosure has been made in consideration of these circumstances, and aims to achieve, in a refrigeration oil and refrigeration device, both the suppression of viscous resistance loss during compressor startup (room temperature) and the improvement of oil film load capacity during operation (high temperature).

To solve the above problems, the refrigeration oil and refrigeration device disclosed herein employ the following measures.

The present disclosure provides a refrigeration oil for a refrigeration device in which propane is sealed as a refrigerant, the refrigeration oil comprising an ester-based base oil having a viscosity grade of ISO VG32 or less and a viscosity index improver containing a polymethacrylic acid ester having an alkyl substituent having 1 to 18 carbon atoms, the concentration of the polymethacrylic acid ester being 0.6 wt% or more and 6 wt% or less.

The present disclosure provides a refrigeration device in which a compressor, a condenser, an expansion valve, and an evaporator are connected by a main pipe to form a refrigerant circulation circuit that circulates a refrigerant, the compressor is provided with a refrigeration oil supply mechanism that supplies refrigeration oil to sliding parts, the refrigeration oil contained in the refrigeration oil supply mechanism contains an ester-based base oil having a viscosity grade of ISO VG32 or less and a viscosity index improver containing a polymethacrylic acid ester having an alkyl substituent having 1 to 18 carbon atoms, the concentration of the polymethacrylic acid ester is 0.6 wt% or more and 6 wt% or less, and propane is sealed in the refrigerant circulation circuit as a refrigerant.

According to the present disclosure, by incorporating a viscosity index improver containing a polymethacrylic acid ester having an alkyl substituent with 1 to 18 carbon atoms into an ester-based base oil, it is possible to realize a refrigeration oil and a refrigeration device equipped with the same that can simultaneously suppress viscous resistance loss during compressor startup (room temperature) and improve oil film load capacity during operation (high temperature).

FIG. 2 is a block diagram of a refrigeration device. FIG. 2 is a vertical cross-sectional view showing a scroll compressor. FIG. 3 is a plan view showing the Oldham link and upper bearing of FIG. 2 . FIG. 4 is a longitudinal sectional view taken at the position of a key of the Oldham link of FIG. 3. FIG. 2 is an evaluation chart of a viscosity index improver. FIG. 2 is a diagram showing the two-phase separation temperature of a mixture of a refrigerating machine oil containing a viscosity index improver and a refrigerant. 1 is a graph summarizing the effect of a viscosity index improver on a base oil.

Below, one embodiment of the refrigeration oil and refrigeration device according to the present disclosure will be described with reference to the drawings.

(Refrigeration oil)
The refrigerating machine oil contains a base oil and a viscosity index improver. The refrigerating machine oil may contain an anti-wear agent. The refrigerating machine oil may contain an oiliness agent, an extreme pressure agent, an antioxidant, an acid scavenger, an antifoaming agent, a leak detection agent, etc. The pour point of the refrigerating machine oil is -45°C or lower.

The base oil is an ester-based synthetic lubricant (ester-based base oil). The ester-based base oil may be, for example, polyol ester, polyvinyl ether, polyalkylene glycol, alkylbenzene, mineral oil, etc. The viscosity grade of the base oil is ISO VG32 or less. The viscosity grade of the base oil is preferably ISO VG22 or more.

Viscosity grade is a viscosity grade of lubricants defined by ISO. The higher the viscosity grade number, the higher the viscosity. The viscosity grade has a kinetic viscosity range defined for each last number, and the number indicates the center value of the kinetic viscosity ( ^mm2 /s). The kinetic viscosity range of ISO VG32 at 40°C is ^28.8mm2 /s or more and ^35.2mm2 /s or less. The kinetic viscosity range of ISO VG22 at 40°C is ^19.8mm2 /s or more and ^24.2mm2 /s or less.

Viscosity index improvers have the effect of reducing the change in viscosity of base oil that occurs with temperature changes.
The viscosity index improver has a structural unit represented by formula (I).
In formula (I), R is an alkyl substituent having 1 to 18 carbon atoms.

The viscosity index improver contains polymethacrylic acid ester (PMA). The molecular weight of the polymethacrylic acid ester is 35,000 or less, preferably about 30,000. In the viscosity index improver, the PMA may be diluted with a solvent. Mineral oil is a suitable solvent. The PMA:solvent ratio may be 60:40 (weight ratio). The viscosity index improver may be, for example, Aclube A-1061 manufactured by Sanyo Chemical Industries, Ltd.

The concentration of polymethacrylic acid ester in the refrigeration oil is 0.6 wt% or more and 6 wt% or less. When using a base oil of viscosity grade ISO VG32, the concentration of polymethacrylic acid ester should be 0.6 wt% or more and 3 wt% or less. When using a base oil of viscosity grade ISO VG22, the concentration of polymethacrylic acid ester should be 3 wt% or more and 6 wt% or less.

The viscosity index (VI) can be improved by blending a viscosity index improver containing polymethacrylic acid ester into the base oil. "Viscosity index" is a value that indicates the degree of viscosity change due to temperature. It is expressed as an index based on the kinematic viscosity at 40°C and 100°C and a standard oil as a reference, and the higher the viscosity index, the smaller the viscosity change. The viscosity index at 40°C of a refrigeration oil using ISO VG32 base oil should be 186±10% to 206±10%. The viscosity index at 40°C of a refrigeration oil using ISO VG22 base oil should be 167±10% to 184±10%. The above viscosity index means a viscosity index measured in accordance with JIS K2283:2000.

In general, the viscosity of a base oil decreases as its temperature increases. By improving the viscosity index of a refrigeration oil, the difference in fluid viscous resistance between start-up and operation can be reduced. Even with the same viscosity grade, a higher viscosity index means higher oil film load capacity at high temperatures. This allows for start-up at low viscosity. Even if the viscosity grade of the base oil is lowered, by adding a viscosity index improver containing polymethacrylate ester, the oil film load capacity at high temperatures will be higher than that of a refrigeration oil that does not contain a viscosity index improver containing polymethacrylate ester.

The anti-wear agent is tributyl phosphate (TBP). The concentration of the anti-wear agent in the refrigeration oil is 1 wt% or more and 5 wt% or less, preferably 1 wt% or more and 3 wt% or less. By including 1 wt% or more of TBP, the wear resistance of the refrigeration oil is significantly improved. If the TBP concentration is 1 wt% or more, the wear resistance does not change significantly even if the concentration is increased thereafter. Therefore, the upper limit of the TBP concentration should be 5 wt% or less, preferably 3 wt% or less.

The refrigeration oil according to this embodiment is suitable for use in a refrigeration device that uses propane (R290 refrigerant) as the refrigerant. When the refrigeration device is in operation, the refrigeration oil becomes mixed with the refrigerant. The refrigeration oil according to this embodiment is compatible with the R290 refrigerant within the operating temperature range of the refrigeration device.

(Refrigeration equipment)
The refrigerating machine oil according to the present embodiment is suitable for use in, for example, home room air conditioners, commercial air conditioners, chillers, car air conditioners, refrigerated/freezer showcases, heat pumps for hot water supply, etc. Fig. 1 illustrates a block diagram of a refrigeration device that uses the refrigerating machine oil according to the present embodiment.

The refrigeration system in FIG. 1 includes a refrigerant circulation circuit having a compressor 1, a condenser 12, an expansion valve 13, and an evaporator 14. The refrigerant circulation circuit is a closed circuit in which the compressor 1, the condenser 12, the expansion valve 13, and the evaporator 14 are connected via pipes 15a to 15d that transport the refrigerant.

The refrigerant circulation circuit is filled with a refrigerant. The refrigerant is propane (R290). The amount of refrigerant filled in the refrigeration device is 300 g or more, preferably 500 g or more.

Refrigeration oil is supplied to the compressor. The refrigeration oil contains an ester-based base oil with a viscosity grade of ISO VG32 or less and a viscosity index improver containing a polymethacrylic acid ester having an alkyl substituent with 1 to 18 carbon atoms, and the concentration of the polymethacrylic acid ester is selected from those having a concentration of 0.6 wt% or more and 6 wt% or less.

In the refrigeration system, the condenser 12 condenses/liquefies the high-temperature, high-pressure refrigerant gas to release heat, the expansion valve 13 adiabatically expands the high-temperature, high-pressure liquid refrigerant that has passed through the condenser 12 to reduce its pressure, the evaporator 14 evaporates/vaporizes the low-temperature, low-pressure liquid refrigerant that has passed through the expansion valve 13 to absorb heat, and the compressor 1 adiabatically compresses the low-temperature, low-pressure refrigerant gas that has passed through the evaporator 14. The high-temperature, high-pressure refrigerant gas that has passed through the compressor 1 is supplied to the condenser 12. By circulating the refrigerant as a heat transfer medium in this closed system, heat is transferred from the evaporator 14 to the condenser 12.

The refrigeration oil supplied to the compressor 1 mixes with the refrigerant and travels through a refrigerant circulation circuit including the evaporator 14, expansion valve 13 and condenser, before returning to the compressor. The refrigeration oil supplied to the refrigeration system is sealed together with the refrigerant within the system, and is used without being replaced for the duration that the refrigeration system is in use.

(Compressor)
The compressor of the refrigeration system may be a scroll compressor or a rotary compressor. The refrigeration oil according to the present embodiment is particularly suitable for use in a scroll compressor equipped with an Oldham link.

Figure 2 is a vertical cross-sectional view of a scroll compressor to which refrigeration oil is applied.

The scroll compressor (scroll fluid machine) 1 is equipped with a fixed scroll 3 and a rotating scroll 4 that revolves around the fixed scroll 3 within a housing 2.

The fixed scroll 3 is fixed to the housing 2 via the upper bearing 21 and has a scroll-shaped wall 33 standing on the end plate 31. The orbiting scroll 4 has a scroll-shaped wall 43 standing on the end plate 41. The wall 33 of the fixed scroll 3 and the wall 43 of the orbiting scroll 4 have approximately the same shape. By rotating the orbiting scroll 4 180° relative to the fixed scroll 3 and meshing the walls 33, 43 with each other, multiple sealed compression spaces R1 are formed.

The orbiting scroll 4 is designed to revolve around the fixed scroll 3 while its rotation is restricted by the Oldham link 23.

The orbiting scroll 4 is rotated by a driving motor 6. The rotating shaft 5 rotated by the motor 6 is connected to the orbiting scroll 4 via a crank pin 27. The crank pin 27 is provided eccentrically with respect to the central axis of the rotating shaft 5. The crank pin 27 is rotatably connected to a boss formed on the back surface (the lower surface in the figure) of the end plate 41 of the orbiting scroll 4 via a drive bush and a drive bearing 52. The rotating shaft 5 is rotatably supported by an upper bearing 21 and a lower bearing 24 fixed to the housing 2.

A storage area 26 for storing refrigeration oil is provided at the bottom of the housing 2. The refrigeration oil is pumped up through an oil supply path 53 inside the rotating shaft 5 by a pump 54 provided at the lower end of the rotating shaft 5, and is supplied to sliding parts such as the lower bearing 24, the upper bearing 21, the drive bearing 52 provided around the crank pin 27, the orbiting scroll 4, and the Oldham link 23. In this embodiment, the storage area 26, the pump 54, and the oil supply path 53 are collectively referred to as the refrigeration oil supply mechanism.

The housing 2 is provided with an intake pipe 28 that draws in low-pressure gas refrigerant and a discharge pipe 29 that discharges compressed high-pressure gas refrigerant. The intake pipe 28 and the discharge pipe 29 are connected to a refrigerant circulation circuit of a refrigeration device (not shown).

The scroll compressor 1 operates as follows.
When a driving current is supplied to the stator 61 of the motor 6 from a power source (not shown), the rotor 62 of the motor 6 rotates, and a driving force is output to the rotating shaft 5 .
When the rotating shaft 5 is rotated, a driving force is transmitted to the orbiting scroll 4 via a crank pin 27 provided at the upper end of the rotating shaft 5 eccentrically in one radially outward direction (eccentric direction) from the central axis of the rotating shaft 5. As a result, the orbiting scroll 4 revolves around the fixed scroll 3 while being prevented from rotating on its own axis by the action of the Oldham link 23.

As the orbiting scroll 4 rotates, the refrigerant flowing in from the suction pipe 28 is sucked into the space between the orbiting scroll 4 and the fixed scroll 3. As the orbiting scroll 4 rotates, the volume of the compression space R1 between the orbiting scroll 4 and the fixed scroll 3 decreases, and the refrigerant is compressed in the compression space R1.

The compressed refrigerant passes through the discharge port 32 of the fixed scroll 3 and the discharge port 38 of the discharge cover 37, and is discharged into the refrigerant circulation circuit through the discharge piping 29. The fixed scroll 3 is formed with a multi-port 32A, which is provided with a reed valve 36 attached to the end plate 31 of the fixed scroll 3 via a retainer 35. The discharge port 38 of the discharge cover 37 is also provided with a reed valve 37B attached to the discharge cover 37 via a retainer 37A. When the pressure of the compressed refrigerant reaches a predetermined value, the refrigerant is forced open by the reed valves 36 and 37B and discharged into the condenser side of the refrigerant circulation circuit.

Figure 3 shows the Oldham link 23 shown in Figure 2. The Oldham link 23 is provided above the upper bearing 21. Also, as shown in Figure 2, the Oldham link 23 is provided on the back side of the end plate 41 of the orbiting scroll 4.

As shown in FIG. 3, the Oldham link 23 is generally ring-shaped when viewed from above. When viewed from above as in FIG. 3, keys 23A protruding downward (toward the upper bearing 21) are provided on both the left and right sides, i.e., at the 3 o'clock and 9 o'clock positions. When viewed from above as in FIG. 3, keys 23B protruding upward (toward the orbiting scroll 4) are provided on both the top and bottom sides, i.e., at the 6 o'clock and 12 o'clock positions. That is, the direction in which the two keys 23A are provided and the direction in which the two keys 23B are provided are provided perpendicular to each other. Each of the keys 23A protruding downward is inserted into a key groove 21A formed in the upper bearing 21 as shown in FIG. 4. Each of the keys 23B protruding upward is inserted into a key groove formed in the end plate 41 of the orbiting scroll 4, not shown.

The upper bearing 21 and the orbiting scroll 4 are preferably made of a material different from that of the Oldham link 23. If the material of the Oldham link 23 is iron, the material of the key grooves formed in the upper bearing 21 and the orbiting scroll 4 is preferably aluminum. If the material of the Oldham link 23 is aluminum, the material of the key grooves formed in the upper bearing 21 and the orbiting scroll 4 is preferably iron.

(Compatibility with R290 refrigerant)
The two-layer separation temperature was measured in accordance with JIS K2211:2009 "Refrigerating machine oil""Test method for compatibility with refrigerants."

The refrigerant used was R290. The viscosity index improver used was a fluid in which polymethacrylate ester (PMA) was diluted with diluent oil. The blending ratio of PMA and diluent oil was as shown in Table 1, No. 1 to 3 (Sanyo Chemical Industries, Ltd.). The base oil used was polyol ester (viscosity grade ISO VG32). PMA has a structural unit represented by the above formula (I) and has an alkyl substituent with 1 to 18 carbon atoms. The concentration of the viscosity index improver in the refrigeration oil was 5 wt%.

Figure 5 shows the evaluation results of the viscosity index improver. The figure shows the two-phase separation temperature of a mixture of viscosity index improver and refrigerant in a ratio of 10:50 (by weight).

Figure 6 shows the two-phase separation temperature of a mixture of refrigerant and refrigerant containing a viscosity index improver. In the mixture shown in the figure, the ratio of refrigerant (containing viscosity index improver No. 3) to refrigerant is 10:90 to 40:60 (weight ratio). In the figure, the curve superimposed on the bar graph is the two-phase separation temperature curve (a) of a mixture of VG32 polyol ester (VG32_POE) and R410 used in conventional refrigerant oils. In the figure, the two-dot chain line shown below the bar graph is the lower limit (b) of the compatibility region of a mixture of VG46 polyol ester (VG46_POE) and R290 used in conventional refrigerant oils. VG32_POE is a refrigerant oil for R410A, etc. VG46_POE is a candidate refrigerant oil for propane.

Viscosity index improver No. 2 separated from the R290 refrigerant over the entire range. On the other hand, No. 1 did not separate at temperatures below 32°C. No. 3 did not separate at temperatures above -26°C. The discharge temperature of a refrigeration system compressor rises to 120°C. For this reason, it is required that the viscosity index improver does not separate on the high temperature side. On the low temperature side, it is sufficient that there is no separation at the outside air temperature. For this reason, viscosity index improver No. 3 is suitable for use in refrigeration system compressors.

The compatibility characteristics of the refrigeration oil containing viscosity index improver No. 3 and the refrigerant were good. The lower limit of the compatibility region (lower temperature side two-phase separation temperature) of the refrigeration oil containing viscosity index improver No. 3 was expanded by approximately 10 to 15°C compared to when No. 3 alone was mixed with R290 refrigerant. It is expected that the compatibility region will tend to narrow as the concentration of the viscosity index improver is increased. The mixing ratio of the refrigeration oil and the refrigerant had almost no effect on the two-phase separation temperature.

It was confirmed that a mixture of refrigeration oil containing viscosity index improver No. 3 and R290 refrigerant has a wider compatibility range (see the two-phase separation temperature curve (a) in Figure 6) than a mixture of refrigeration oil and refrigerant used in conventional refrigeration equipment, and that it can maintain the same compatibility characteristics (see the lower limit of the compatibility range (b) in Figure 6). From the above, it was confirmed that a mixture of refrigeration oil containing viscosity index improver No. 3 and R290 refrigerant can be used within the operating temperature range of conventional refrigeration equipment.

(Concentration of Viscosity Index Improver)
For refrigerator oils in which a viscosity index improver was added to ester-based base oils of different viscosity grades, the kinematic viscosities at 40°C and 100°C were measured, and the viscosity index (VI) was calculated from the results.

Table 2 shows the test conditions and the results. For reference, Table 2 lists the acid value, kinematic viscosity, and viscosity index (VI) of base oils with different viscosity grades. No. 3 in Table 1 above was used as the viscosity index improver. Samples No. 3 to 6 of the refrigeration oil contained tributyl phosphate (TBP) as an anti-wear agent.

The viscosity index improver (No. 3 in Table 1) did not impair the properties of the refrigeration oil when added to an ester-based base oil.

For base oils without added viscosity index improver (samples No. 1, 2, 7, 8), the higher the viscosity grade, the higher the viscosity index. By adding a viscosity index improver to a base oil with a viscosity grade of ISO VG32, the viscosity index of the refrigeration oil was improved. The viscosity index also increased with an increase in the concentration of the viscosity index improver. By adding 5 wt% viscosity index improver (3 wt% PMA), the viscosity index was approximately 10% higher than that of the base oil before addition. This was approximately 5% higher than the viscosity index of ISO VG46.

As the viscosity index improver concentration increased, the kinematic viscosity at 40°C and 100°C increased. In sample No. 5, which had a viscosity index improver concentration of 10 wt% (PMA 6 wt%), the kinematic viscosity at 40°C and 100°C was close to that of ISO VG46, even though ISO VG32 base oil was used. The kinematic viscosity at 40°C was lower than that of ISO VG46 base oil up to a viscosity index improver concentration of 10 wt% (PMA 6 wt%).

According to the above results, by adding a viscosity index improver, the viscosity index of a refrigeration oil using a base oil with a viscosity grade of ISO VG32 can be made equal to or higher than that of ISO VG46. Refrigeration oil containing 10 wt% or less of viscosity index improver (PMA 6 wt%) (sample No. 5) can start up at a kinetic viscosity lower than ISO VG46, and during operation, it exhibits a kinetic viscosity equivalent to ISO VG46. Refrigeration oil containing 5 wt% (PMA 3 wt%) of viscosity index improver (sample No. 4) can start up at a kinetic viscosity approximately 25% lower than ISO VG46, and can operate at a kinetic viscosity approximately 20% higher than before the addition of the viscosity index improver.

Figure 7 shows a graph summarizing the effect of viscosity index improvers on base oils. In the figure, the horizontal axis is the viscosity index improver concentration (wt%), and the vertical axis is the 40°C kinematic viscosity ( ^mm2 /s) or viscosity index (VI). The viscosity index improver concentration in Figure 7 is based on the assumption that viscosity index improver No. 3 in Table 1 is used.

As the concentration of the viscosity index improver increases, the kinetic viscosity and viscosity index at 40°C improve almost linearly. If the concentration of the viscosity index improver is 10 wt% or less (PMA 6 wt%), the kinetic viscosity at low temperatures (40°C) will not become too high. If the viscosity grade of the base oil is ISO VG32, the 40°C kinetic viscosity can be reliably made lower than ISO VG46 by setting the concentration of the viscosity index improver to 1-5 wt% (PMA 0.6-3 wt%). If the viscosity grade of the base oil is ISO VG22, the 40°C kinetic viscosity can be made lower than ISO VG46 even if the concentration of the viscosity index improver is 5-10 wt% (PMA 3-6 wt%).

<Additional Notes>
The refrigeration oil and the refrigeration device described in the above-described embodiment can be understood, for example, as follows.

The refrigeration oil according to the first aspect of the present disclosure is a refrigeration oil for a refrigeration device in which propane is filled as a refrigerant, and includes an ester-based base oil having a viscosity grade of ISO VG32 or less, and a viscosity index improver including a polymethacrylic acid ester having an alkyl substituent having 1 to 18 carbon atoms, and the concentration of the polymethacrylic acid ester is 0.6 wt% or more and 6 wt% or less.

According to the present disclosure, the viscosity index can be improved by adding the polymethacrylic acid ester to an ester-based base oil. This allows the kinetic viscosity to be maintained at high temperatures even when a base oil with a low viscosity grade is used. By using a base oil with a low viscosity grade, frictional resistance at room temperature can be reduced. Since the kinetic viscosity can be maintained at high temperatures, the oil film load capacity during operation (high temperature) is improved compared to base oils without the addition of polymethacrylic acid ester.

When using ISO VG32 ester base oil, the concentration of polymethacrylic acid ester should be 0.6 wt% or more and 3 wt% or less. This allows the kinetic viscosity at start-up to be lower than that of ISO VG46 base oil, while ensuring a kinetic viscosity equal to or higher than that of ISO VG46 during operation.

The refrigeration oil according to the second aspect of the present disclosure may further contain tributyl phosphate as an anti-wear agent in the first aspect, and the concentration of the anti-wear agent may be 1 wt% or more and 5 wt% or less.

By adding 1 wt% or more of TBP, the wear resistance of the refrigeration oil is significantly improved.

The refrigeration device according to the third aspect of the present disclosure is a refrigeration device in which a compressor (1), a condenser (12), an expansion valve (13), and an evaporator (14) are connected by main pipes (15a-15d) to form a refrigerant circulation circuit for circulating a refrigerant, the compressor is equipped with a refrigeration oil supply mechanism (26, 54, 53) that supplies refrigeration oil to sliding parts (24, 21, 52, 4, 23), the refrigeration oil contained in the refrigeration oil supply mechanism includes an ester-based base oil having a viscosity grade of ISO VG32 or less and a viscosity index improver including a polymethacrylic acid ester having an alkyl substituent having 1 to 18 carbon atoms, the concentration of the polymethacrylic acid ester is 0.6 wt% or more and 6 wt% or less, and propane is sealed in the refrigerant circulation circuit as a refrigerant.

The refrigeration device according to the fourth aspect of the present disclosure is the third aspect, in which the amount of the refrigerant charged is 300 g or more.

The refrigeration device according to the fifth aspect of the present disclosure is the third or fourth aspect, in which the compressor is a scroll compressor equipped with an Oldham link (23) as an anti-rotation mechanism.

1 Compressor (scroll compressor, scroll fluid machine)
Reference Signs List 2 Housing 3 Fixed scroll 4 Orbiting scroll 12 Condenser 13 Expansion valve 14 Evaporator 15a to 15d Pipe 21 Upper bearing 21A Key groove 23 Oldham link 23A Key 23B Key 24 Lower bearing 26 Storage area 27 Crank pin 28 Suction pipe 29 Discharge pipe 31 End plate 32, 38 Discharge port 32A Multi-port 33 Wall body 35 Retainer 36 Reed valve 37 Discharge cover 37A Retainer 37B Reed valve 41 End plate 43 Wall body 52 Drive bearing R1 Compression space

Claims (5)

A refrigeration oil for a refrigeration device containing propane as a refrigerant,
an ester-based base oil having a viscosity grade of ISO VG32 or less;
a viscosity index improver comprising a polymethacrylic acid ester having an alkyl substituent having 1 to 18 carbon atoms;
The concentration of the polymethacrylic acid ester in the refrigeration oil is 0.6 wt % or more and 6 wt % or less. further comprising tributyl phosphate as an antiwear agent;
2. The refrigeration oil according to claim 1, wherein the concentration of the anti-wear agent is 1 wt % or more and 5 wt % or less. A refrigeration apparatus including a refrigerant circulation circuit in which a compressor, a condenser, an expansion valve, and an evaporator are connected by a main pipe to circulate a refrigerant,
The compressor includes a refrigeration oil supply mechanism for supplying refrigeration oil to a sliding portion,
The refrigeration oil contained in the refrigeration oil supply mechanism includes an ester-based base oil having a viscosity grade of ISO VG32 or less, and a viscosity index improver including a polymethacrylic acid ester having an alkyl substituent having 1 to 18 carbon atoms, and a concentration of the polymethacrylic acid ester is 0.6 wt % or more and 6 wt % or less,
The refrigeration apparatus, wherein propane is sealed as the refrigerant in the refrigerant circulation circuit. The refrigeration device according to claim 3, wherein the amount of the refrigerant charged is 300 g or more. The refrigeration system according to claim 3, wherein the compressor is a scroll compressor equipped with an Oldham link as a rotation prevention mechanism.