JP2014001255A - Compressor and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of a compressor by inhibiting leakage of a refrigerant.SOLUTION: In a compressor which is provided with a compression chamber having a sliding part and includes difluoromethane as a refrigerant and a refrigerating machine oil. The refrigerating machine oil is a polyol ester oil which is a mixture of a compound represented by a chemical formula (1) (wherein Ris an alkyl group having 3-8 carbon atoms) and a compound represented by a chemical formula (2), contains 20 mol% or more of the compound represented by the chemical formula (2), and has a kinematic viscosity of 30-90 mm/s at 40°C, the low temperature-side critical solution temperature of the refrigerant and the polyol ester oil is +10°C or lower, and the polyol ester oil contains 1-30 wt% of a compression part sealant having a kinematic viscosity of more than 180 mm/s at 40°C based on the polyol ester oil.

Description

  The present invention relates to a compressor and an air conditioner.

  R410A, a refrigerant used in the field of air conditioning equipment, is a mixture of HFC (Hydrofluorocarbons) 32 / HFC125 (50/50 wt%) and has a high GWP (Global Warming Potential) = 2088. Therefore, an alternative refrigerant with a low GWP is used. There is an urgent need to develop an air conditioning system.

  As this alternative refrigerant, 2,3,3,3-tetrafluoropropene (HFO1234yf (Hydrofluoroolefin) (GWP = 4), 1,3,3) is used for reasons such as thermophysical properties, low GWP, low toxicity, and low flammability. , 3-tetrafluoropropene (HFO1234ze) (GWP = 10) or difluoromethane (HFC32) alone or a mixture of these refrigerants, other refrigerants include hydrocarbons such as propane and propylene, and Low GWP hydrofluorocarbons such as fluoroethane (HFC161), difluoroethane (HFC152a), etc. Among these refrigerant candidates, combustibility, cooling / heating capability, equipment efficiency decrease due to temperature gradient of non-azeotropic refrigerant, handling Considering ease, refrigerant costs, equipment changes (development), etc. Trifluoromethane (HFC32) is the best.

  The refrigeration oil is used in a hermetic electric compressor and plays a role of lubrication, sealing, cooling and the like of the sliding part. One of the important characteristics of refrigeration oil is its compatibility with refrigerants. However, since HFC32 has low compatibility with refrigerating machine oil, for example, Patent Document 1, Patent Document 2, and Patent Document 3 disclose refrigerating machine oil having improved compatibility with HFC32.

JP 2010-235960 A JP 2002-129178 A

  However, since the HFC 32 has a small adiabatic index, the discharge temperature becomes high, and thus the temperature of the compressor also becomes high, so that overheating loss occurs when the refrigerant is sucked. Furthermore, since the molecular weight is small and the molecular velocity is high, refrigerant leakage from the compression part of the compressor is likely to occur. For this reason, a decrease in compressor efficiency due to a decrease in volumetric efficiency occurs. None of the above-mentioned patent documents sufficiently considers refrigerant leakage.

  An object of the present invention is to improve refrigerant efficiency by suppressing refrigerant leakage.

In order to achieve the above object, the present invention is a compressor including a compression chamber having a sliding portion and enclosing difluoromethane, which is a refrigerant, and refrigerating machine oil, wherein the refrigerating machine oil is represented by the chemical formula (1). Is a mixture of the compound represented by the chemical formula (2) and the compound represented by the chemical formula (2), wherein R ^{1 to} R ⁶ are alkyl groups having 3 to 8 carbon atoms. It is a polyol ester oil having a kinematic viscosity at 40 ° C. of 30 to 90 mm ² / s, containing at least mol%, and having a low temperature side critical solution temperature of + 10 ° C. or less between the refrigerant and the polyol ester oil. 1-30 weight% of the compression part sealing agent with a kinematic viscosity in 40 degreeC exceeding 180 mm < ² > / s is included with respect to the said polyol ester oil, It is characterized by the above-mentioned.

  According to the present invention, it is possible to improve refrigerant efficiency by suppressing refrigerant leakage.

It is the schematic which shows the structure of an air conditioner. It is sectional drawing which shows a scroll-type hermetic compressor.

Examples of the present invention will be described in detail below.
The compressor includes a compression chamber having a sliding portion, and encloses difluoromethane, which is a refrigerant, and refrigerating machine oil. Here, the refrigerating machine oil is a compound represented by the following chemical formula (1) having a kinematic viscosity of 30 to 90 mm ² / s at 40 ° C. and a compound represented by the chemical formula (2) (wherein R ^{1 to} R ⁶ are Represents a C 3-8 alkyl group, which may be the same or different, and is a polyol ester oil containing 20 mol% or more of the compound represented by the chemical formula (2). And the low temperature side critical melt | dissolution temperature of a refrigerant | coolant and a polyol ester oil is +10 degrees C or less, and 1-30 weight% with respect to a polyol ester oil is a compression part sealing agent with a kinematic viscosity in 40 degreeC exceeding 180 mm < ² > / s. Contains refrigeration oil.

  The embodiment discloses a compressor using difluoromethane and an air conditioner using the compressor. The refrigerant is difluoromethane, and the refrigerating machine oil is polyol ester oil.

  The polyol ester oil is obtained by a condensation reaction between a polyhydric alcohol and a monovalent fatty acid. As the polyol ester oil, a hindered type having excellent heat stability is preferable, and as the polyhydric alcohol used as a raw material, pentaerythritol and dipentaerythritol are preferable.

  Examples of the monovalent fatty acid used as a raw material include n-butanoic acid, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-methylpropionic acid, 2-methylbutanoic acid, 3- There are methylbutanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, 3,5,5-trimethylhexanoic acid, etc. Used by mixing.

The viscosity grade of the refrigerating machine oil varies depending on the type of the compressor, but in the scroll compressor, the kinematic viscosity at 40 ° C. is preferably in the range of 46 to 90 mm ² / s. In the rotary compressor, the kinematic viscosity at 40 ° C. is preferably in the range of 30 to 70 mm ² / s.

The compression part sealant is a liquid compound having a kinematic viscosity at 40 ° C. exceeding 180 mm ² / s. In the case of a hindered type polyol ester oil, dipentaerythritol fatty acid ester (chemical formula (3) (wherein R ⁷ and R ⁸ are alkyl groups having 7 to ⁸ carbon atoms)) tends to have high viscosity, Leakage can be reduced. Dipentaerythritol is not a pure substance because it contains a large amount of pentaerythritol, tripentaerythritol, and the like as raw materials, but here it will be expressed as dipentaerythritol. Also, complex type polyol ester oil (complex ester oil) (chemical formula (4) (wherein R ⁹ and R ¹⁰ are alkyl groups having 3 to 9 carbon atoms, R ¹¹ is an alkyl group having 1 to 9 carbon atoms, n Is an ester compound in which a polyhydric alcohol, a divalent fatty acid and a monovalent fatty acid are bonded.

  Here, what is preferable as a polyhydric alcohol used as a raw material is, for example, neopentyl glycol, trimethylolpropane and pentaerythritol. The monovalent fatty acid used as a raw material includes n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2 -Ethylhexanoic acid, isooctanoic acid, 3,5,5-trimethylhexanoic acid and the like are used alone or in combination of two or more. Furthermore, as the divalent fatty acid as a raw material, there are propanedioic acid, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, etc., and these may be used alone or in combination of two or more. Use. The dipentaerythritol fatty acid ester described above may be mixed, or a normal polyol ester oil component or the like may be mixed for viscosity adjustment.

  In addition, the ethylene-α-olefin copolymer is easy to obtain an arbitrary high viscosity, is excellent in shear stability, and has a number average molecular weight of 800 to 4000. As the α-olefin constituting the ethylene-α-olefin copolymer, those having 3 to 10 carbon atoms are used, and propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-octene, Examples include 1-decene. These α-olefins may be used singly or in combination of two or more. Moreover, as for ethylene content, 20-80 mol% is more preferable, Any of an alpha olefin and random and block copolymerization may be sufficient.

  Even if a lubricity improver, an antioxidant, an acid scavenger, an antifoaming agent, a metal deactivator, etc. are added to the refrigerating machine oil, there is no problem. In particular, the polyol ester oil is deteriorated due to hydrolysis in the presence of moisture, and therefore, an antioxidant and an acid scavenger are preferably blended.

  As the antioxidant, DBPC (2,6-di-t-butyl-p-cresol) which is a phenol type is preferable. As the acid scavenger, an aliphatic epoxy compound or a carbodiimide compound, which is a compound having an epoxy ring, is generally used. In particular, carbodiimide compounds are extremely reactive with fatty acids and capture hydrogen ions dissociated from fatty acids, so the effect of suppressing the hydrolysis reaction of polyol ester oil is very large. Examples of the carbodiimide compound include bis (2,6-isopropylphenyl) carbodiimide. The amount of the acid scavenger is preferably 0.05 to 1.0% by weight with respect to the refrigerating machine oil.

  FIG. 1 shows an outline of an air conditioner. The air conditioner includes an indoor unit 1 and an outdoor unit 2. An indoor heat exchanger 5 is built in the indoor unit 1. The outdoor unit 2 includes a compressor 3, a four-way valve 4, an outdoor heat exchanger 7, and an expansion device 6.

  When the room is cooled, the high-temperature and high-pressure refrigerant gas compressed in an adiabatic manner by the compressor 3 is cooled by the indoor heat exchanger 5 (used as a condensing means) through the discharge pipe and the four-way valve 4, It becomes a high-pressure liquid refrigerant. This refrigerant expands in the expansion device 6 (for example, a temperature type expansion valve), becomes a low-temperature low-pressure liquid containing a slight amount of gas, reaches the outdoor heat exchanger 7 (used as an evaporation means), and indoor air Then, the heat is obtained, and the refrigerant reaches the compressor 3 through the four-way valve 4 again in the state of low-temperature gas. When the room is heated, the flow of the refrigerant is changed in the reverse direction by the four-way valve 4, and the reverse action occurs.

  As the compressor 3, a scroll type compressor was used. FIG. 2 shows a schematic structure of the scroll compressor. The compressor 3 includes a fixed scroll member 8 having a spiral wrap 10 provided perpendicularly to an end plate 9, a revolving scroll member 11 having a wrap 12 having substantially the same shape as the fixed scroll member 8, and a revolving scroll. It includes a frame 16 that supports the member 11, a crankshaft 13 that orbits the orbiting scroll member 11, an electric motor 19, and a pressure vessel 17 that houses these. The spiral wrap 10 and the wrap 12 are engaged with each other so as to form a compression portion.

  When the orbiting scroll member 11 is orbitally moved by the crankshaft 13, the outermost compression chamber 14 of the compression chambers 14 formed between the fixed scroll member 8 and the orbiting scroll member 11 is orbitally moved. As the volume is gradually reduced, the fixed scroll member 8 and the orbiting scroll member 11 move toward the center. When the compression chamber 14 reaches the vicinity of the center of the fixed scroll member 8 and the orbiting scroll member 11, the compression chamber 14 communicates with the discharge port 15, and the compressed gas inside the compression chamber 14 is discharged from the discharge pipe 18 to the outside of the compressor 3. Discharged.

  In the compressor 3, the crankshaft 13 rotates at a constant speed or at a rotational speed corresponding to a voltage controlled by an inverter (not shown) to perform a compression operation. An oil reservoir 22 is provided below the electric motor 19, and the oil in the oil reservoir 22 passes through an oil hole 21 provided in the crankshaft 13 due to a pressure difference, and the orbiting scroll member 11. This is used for lubrication of the sliding portion with the crankshaft 13, the sliding bearing 20, and the like.

(Examples 1 to 3 and Comparative Examples 1 and 2)
Based on the Japanese Industrial Standard (JIS C 9612-2005; room air conditioner), year-round energy consumption efficiency APF was calculated. Separately, a compressor performance test was performed to measure volumetric efficiency from representative conditions. The refrigerant used in the examples is difluoromethane, and the refrigerating machine oil as the main agent and the compression part sealing agent as the additive are shown below.

(Refrigerator oil)
(A) Hindered type polyol ester oil (pentaerythritol / dipentaerythritol 2-methylbutanoic acid / 2-ethylhexanoic acid mixed fatty acid ester oil)
: 40 ° C viscosity 68.7 mm ² / s
(B) hindered type polyol ester oil (pentaerythritol-based 2-ethylhexanoic acid / 3,5,5-trimethylhexanoic acid mixed fatty acid ester oil): 40 ° C. viscosity 64.9 mm ² / s

(Compression part sealant)
(F) Hindered type polyol ester oil (dipentaerythritol-based 2-ethylhexanoic acid / 3,5,5-trimethylhexanoic acid mixed fatty acid ester oil): 40 ° C.
Viscosity 217mm ² / s
(G) Complex type polyol ester oil (neopentyl glycol, dicarboxylic acid, and monocarboxylic acid ester, adipic acid as dicarboxylic acid, 3,5,5-trimethylhexanoic acid as monocarboxylic acid Ester oil):
40 ° C viscosity 260mm ² / s
(H) ethylene-α-olefin copolymer (trade name: Lucant HC-40: manufactured by Mitsui Chemicals, Lucant is a registered trademark of the company): 40 ° C. viscosity 380 mm ² / s

In Examples 1 to 3, 5.0% by weight of (F), (G), and (H) as blending part sealants was blended with the refrigerating machine oil (A). In any case, the kinematic viscosity of the refrigerating machine oil after blending is around 70 mm ² / s. The refrigerating machine oil (A) is a refrigerating machine oil having a low-temperature side critical dissolution temperature with difluoromethane of −2 ° C. and exhibiting compatibility. As described above, the compatibility of refrigerant and refrigeration oil enclosed in the compressor is the reliability of the compressor, such as the return of oil from the refrigeration cycle to the compressor (to ensure the amount of oil inside the compressor) or the maintenance of heat exchange efficiency. This is one of the important characteristics in terms of guaranteeing safety. The compatibility evaluation of difluoromethane and refrigerating machine oil was measured according to JIS K 2211. In the compatibility evaluation, a graph was created with the horizontal axis representing the concentration of oil mixed in the refrigerant (oil concentration) and the vertical axis representing the dissolution temperature. This graph generally shows the oil concentration dependence of the temperature at which the two layers are separated, and is a curve having a maximum value. This maximum value was defined as the low temperature critical solution temperature.

  In the comparative example 1, it was set as the combination using refrigerant | coolant R410A and refrigeration oil (B) which are used with the present apparatus. The low temperature side critical dissolution temperature is + 9 ° C., and no compression part sealant is blended. The comparative example 1 was set to 100% efficiency reference value (APF ratio). The comparative example 2 was made into the combination by which the compressor sealing agent was not mix | blended from Examples 1-3. As the measurement items, the year-round energy consumption efficiency APF and the volumetric efficiency ratio of the compressor were compared under the four conditions of heating rating, heating middle, cooling rating, and cooling middle, which are typical operation conditions of the air conditioner. The APF and volumetric efficiency ratio of Examples 1 to 3 and Comparative Example 2 were examined using the current device of Comparative Example 1 as the reference 100%.

  Table 1 shows the results. Comparing Comparative Example 1 and Comparative Example 2, when difluoromethane is used, the APF is improved by about 1.0%. This is considered that APF improves because the latent heat of difluoromethane is large and the pressure loss is small. However, when looking at the volumetric efficiency of the compressor, the volumetric efficiency of the compressor using difluoromethane decreases under any conditions, even though the APF has improved. Since difluoromethane has a small adiabatic index and a high discharge temperature, the temperature of the compressor is also high, and overheating loss during suction is likely to occur. Furthermore, since the molecular weight is small and the molecular velocity is high, the refrigerant is liable to leak from the compression part of the compressor, resulting in a decrease in volume efficiency. On the other hand, as shown in Examples 1 to 3, the volumetric efficiency of the compressor is improved as compared with Comparative Example 2 in the air conditioning apparatus in which 5% by weight of the compression sealant is blended with difluoromethane and the refrigerating machine oil (A). It has been found that the APF of the device also increases.

(Examples 4 to 6 and Comparative Examples 3 and 4)
In Examples 4 to 6, the lubricity of the refrigerating machine oil was evaluated. The lubricity of refrigeration oil was evaluated using a shell-type four-ball frictional wear tester. Wear test piece diameters (average of 3 pieces) and friction after test with 1/2 inch SUJ2 steel ball as test piece, load: 280 N, temperature: 120 ° C., rotational speed: 1200 / min, time: 10 min The coefficient was measured. The refrigerating machine oil (B) and the compression part sealant (F) are the same as those in Examples 1 to 3.

(Refrigerator oil)
(A) Hindered type polyol ester oil (pentaerythritol / dipentaerythritol 2-methylbutanoic acid / 2-ethylhexanoic acid mixed fatty acid ester oil)
: 40 ° C viscosity 68.7 mm ² / s
Dipentaerythritol compounding amount about 50 mol%
(C) hindered type polyol ester oil (pentaerythritol / dipentaerythritol mixed fatty acid ester oil of 2-methylbutanoic acid / 2-ethylhexanoic acid)
: 40 ° C viscosity 67.3 mm ² / s
Dipentaerythritol compounding amount about 35 mol%
(D) Hindered type polyol ester oil (pentaerythritol / dipentaerythritol 2-methylbutanoic acid / 2-ethylhexanoic acid mixed fatty acid ester oil)
: 40 ° C viscosity 66.2 mm ² / s
Dipentaerythritol compounding amount approximately 25 mol%
(E) Hindered type polyol ester oil (pentaerythritol / dipentaerythritol 2-methylbutanoic acid / 2-ethylhexanoic acid mixed fatty acid ester oil)
: 40 ° C viscosity 65.3 mm ² / s
Dipentaerythritol compounding amount about 10 mol%

  As refrigerating machine oils, (A), (C), and (D) contain 20 mol% or more of dipentaerythritol, and 5.0% by weight of (F) is added to any refrigerating machine oil as a compression part sealant.

  Table 2 shows the results of evaluating the lubricity of each refrigeration oil. As shown in Comparative Example 4, when dipentaerythritol is not blended in the refrigerator oil component, the wear scar diameter is large and the friction coefficient is high. On the other hand, as shown in Examples 4 to 6, a blend of 20% by weight or more of dipentaerythritol in the refrigerating machine oil component has reduced wear scar diameter and friction coefficient, and is excellent in lubricity. I understand that. This is because dipentaerythritol has a large adsorption capacity to the friction surface, the surface energy of the friction surface is reduced, and the effect of reducing wear resistance and friction coefficient is obtained. As shown in Comparative Example 3, it was found that when the amount of dipentaerythritol blended in the refrigerating machine oil component was less than 20% by weight, the wear scar diameter was large, the friction coefficient was high, and sufficient lubricity could not be obtained.

(Examples 7 to 9 and Comparative Examples 5 and 6)
Next, the refrigerating machine oil and the compression part sealant whose effects were confirmed in Example 1 were used to study the blending amount of the compressor sealant. Measurement items, measurement method, refrigerator oil (A), and compression section sealant (F) are the same as those in Examples 1-3.

  In Examples 7-9, (F) was mix | blended with refrigeration oil (A) as a compression part sealing agent in the range of 1-30 weight%. In Comparative Example 5, (F) was 0.5% by weight as the compression part sealant, and in Comparative Example 6, 40% by weight (F) was blended as the compression part sealant.

  The results are shown in Table 3. Compared with Comparative Example 2, in Examples 7 to 9, APF is improved by 0.5 to 1.0%. This is due to the effect of improving the sealing performance of the compression part of the compressor by the compression part sealant. On the other hand, as shown in Comparative Example 5, in the embodiment in which (F) is 0.5% by weight as the compression part sealant, the volume efficiency and APF of the compressor are improved as compared with Comparative Example 2. Not. Further, as shown in Comparative Example 6, when 40 wt% of (F) is blended as the compression part sealant, the kinematic viscosity of the refrigerating machine oil is greatly increased, and the APF is decreased due to an increase in the viscous resistance. To do. For this reason, the blending amount of the compression section sealant with respect to the refrigerating machine oil is preferably in the range of 1.0 to 30% by weight.

  From the above results, it is possible to reduce refrigerant leakage from the compressor section of the compressor, improve the volume efficiency of the compressor, and improve the year-round energy consumption efficiency APF of the air conditioner.

  As a compressor, in addition to a scroll compressor, a rotary compressor, a twin rotary compressor, a two-stage compression rotary compressor, and a swing compressor in which a roller and a vane are integrated have the same effect. It was confirmed that it was obtained.

  The present invention is applicable to a compressor and an air conditioner.

1 indoor unit 2 outdoor unit 3 compressor 4 four-way valve 5 indoor heat exchanger 6 expansion device 7 outdoor heat exchanger 8 fixed scroll member 9 end plate 10 spiral wrap 11 orbiting scroll member 12 lap 13 crankshaft 14 compression chamber 15 discharge Outlet 16 Frame 17 Pressure vessel 18 Discharge pipe 19 Electric motor 20 Sliding bearing 21 Oil hole 22 Oil reservoir

Claims (4)

In a compressor provided with a compression chamber having a sliding portion and enclosing difluoromethane, which is a refrigerant, and refrigerating machine oil,
The refrigerating machine oil is a mixture of a compound represented by the chemical formula (1) (wherein R ^{1 to} R ⁶ are alkyl groups having 3 to 8 carbon atoms) and a compound represented by the chemical formula (2), A polyol ester oil containing 20 mol% or more of the compound represented by the chemical formula (2) and having a kinematic viscosity at 40 ° C. of 30 to 90 mm ² / s,
The low-temperature side critical dissolution temperature of the refrigerant and the polyol ester oil is + 10 ° C. or lower,
The compressor characterized in that the polyol ester oil contains 1 to 30% by weight of a compression sealant having a kinematic viscosity at 40 ° C. exceeding 180 mm ² / s with respect to the polyol ester oil.
The compression part sealant is a compound represented by the following chemical formula (3) (wherein R ⁷ and R ⁸ are alkyl groups having 7 to 8 carbon atoms) or a compound represented by the chemical formula (4) (wherein R ⁹ and R ¹⁰ are alkyl groups having 3 to 9 carbon atoms, R ¹¹ is an alkyl group having 1 to 9 carbon atoms, and n is a positive number) or an ethylene-α-olefin copolymer having a number average molecular weight of 800 to 4000. The compressor according to claim 1, wherein the compressor is provided.
The compressor according to claim 1, wherein the compression chamber is formed of an orbiting scroll member and a fixed scroll member, and has a kinematic viscosity at 40 ° C. of 46 to 90 mm ² / s.   An air conditioner in which the compressor according to any one of claims 1 to 3, a condenser, an expansion device, and an evaporator are connected by piping.