WO2013187084A1

WO2013187084A1 - Compressor and air conditioner

Info

Publication number: WO2013187084A1
Application number: PCT/JP2013/053351
Authority: WO
Inventors: 亮太田; 井関　崇; 荒木　邦成; 村上　晃啓; 高藤　亮一
Original assignee: 日立アプライアンス株式会社
Priority date: 2012-06-15
Filing date: 2013-02-13
Publication date: 2013-12-19
Also published as: JP2014001255A; CN104379713B; CN104379713A; JP5872387B2

Abstract

Provided is a compressor which comprises a compression chamber having a sliding portion and in which difluoromethane which is a refrigerant and a refrigerating machine oil are enclosed, wherein the refrigerating machine oil contains two prescribed types of polyol ester oils (a first polyol ester oil and a second polyol ester oil) and contains 20 mol% or more of the second polyol ester oil. The lower temperature side critical solution temperature of the mixture of the refrigerant and the first polyol ester oil and the second polyol ester oil is +10°C or less. The refrigerating machine oil further contains a compression portion sealing agent which has a kinematic viscosity at 40°C of over 180 mm²/s and which is contained in an amount of 1 to 30 parts by weight with respect to 100 parts by weight of the mixture. The kinematic viscosity of the refrigerating machine oil at 40°C is 30 to 90 mm²/s. According to the above, refrigerant leakage can be suppressed and efficiency of the compressor can be improved.

Description

Compressor and air conditioner

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

Refrigerant R410A used in the air conditioning field is a mixture of HFC (Hydrofluorocarbons) 32 / HFC 125 (50/50 wt%), and GWP (Global Warming Potential) = 2088, so alternative refrigerants with low GWP are used. There is an urgent need to develop an air conditioner that

As this alternative refrigerant, 2,3,3,3-tetrafluoropropene (HFO 1234yf (Hydrofluoroolefin) (GWP = 4), 1, 3, 3 because of thermal properties, low GWP, low toxicity, low flammability, etc. -3-, 3-tetrafluoropropene (HFO 1234ze) (GWP = 10) or difluoromethane (HFC 32) as a single refrigerant or a mixed refrigerant of these is a candidate. Other refrigerants include hydrocarbons such as propane and propylene, and Low GWP hydrofluorocarbons such as fluoroethane (HFC 161), difluoroethane (HFC 152a), etc. Among these refrigerant candidates, flammability, heating and cooling capacity, equipment efficiency decrease due to non-azeotropic refrigerant temperature gradient, handling Considering ease, refrigerant cost, equipment change (development), etc. Difluoromethane (HFC32) is the best.

Refrigerant oil is used in a hermetic electric compressor and plays a role of lubricating, sealing, cooling and the like of the sliding portion thereof. One of the important characteristics of refrigeration oil is its compatibility with the refrigerant. However, since HFC32 has low compatibility with refrigeration oil, for example, Patent Literature 1 and Patent Literature 2 disclose refrigeration oil having improved compatibility with HFC32.

JP, 2010-235960, A JP 2002-129178 A

Since the HFC 32 has a low adiabatic index, the discharge temperature is high, which also increases the temperature of the compressor. For this reason, an overheat loss occurs at the time of refrigerant suction. Furthermore, since the molecular weight is small and the molecular velocity is high, refrigerant leakage from the compression unit of the compressor is likely to occur. For this reason, a reduction in compressor efficiency due to a reduction in volumetric efficiency occurs. The refrigeration oil described in Patent Documents 1 and 2 is not sufficiently considered for refrigerant leakage.

An object of the present invention is to suppress refrigerant leakage to improve compressor efficiency.

In order to achieve the above object, the present invention provides a compressor provided with a compression chamber having a sliding portion and containing difluoromethane as a refrigerant and refrigeration oil, wherein the refrigeration oil is represented by the following chemical formula (1) And a second polyol ester oil represented by the following chemical formula (2) (wherein, R ¹ to R ⁶ are an alkyl group having 3 to 8 carbon atoms): The low-temperature critical solution temperature of the refrigerant and the mixture of the first polyol ester oil and the second polyol ester oil, which contains 20 mol% or more of the second polyol ester oil, is + 10 ° C. or less; kinematic viscosity at ° C. further comprises a compression seal material exceeding 180 mm 2 / ^s, the compression seal material is 1 to 30 parts by weight with respect to the 100 parts by weight of the mixture, kinematic viscosity at 40 ° C. of the refrigerating machine oil Characterized in that it is a 30 ~ 90mm ² / s.

According to the present invention, it is possible to suppress the refrigerant leakage and improve the compressor efficiency.

It is the schematic which shows the structure of an air conditioner. 1 is a cross-sectional view showing a scroll-type hermetic compressor.

Hereinafter, embodiments of the present invention will be described in detail.

The compressor is provided with a compression chamber having a sliding portion, in which difluoromethane as a refrigerant and refrigerant oil are enclosed. Here, the refrigerator oil includes a first polyol ester oil represented by the following chemical formula (1) and a second polyol ester oil represented by the following chemical formula (2) (wherein, R ¹ to R ⁶ Is an alkyl group having 3 to 8 carbon atoms) and 20 mol% or more of the second polyol ester oil. And the low temperature side critical solution temperature of the refrigerant and the mixture of the first polyol ester oil and the second polyol ester oil is + 10 ° C. or less, and the refrigerator oil has a kinematic viscosity at 40 ° C. exceeding 180 mm ² / s The compressor seal further comprises 1 to 30 parts by weight with respect to 100 parts by weight of the mixture, and the kinematic viscosity at 40 ° C. of the refrigerator oil is 30 to 90 mm ² / s.

The present embodiment discloses a compressor using difluoromethane and an air conditioner using the same. The refrigerant is difluoromethane, and the refrigerator oil is a polyol ester oil.

The polyol ester oil is obtained by the condensation reaction of a polyhydric alcohol and a monohydric fatty acid. As the polyol ester oil, a hindered type excellent in thermal stability is preferable, and as the raw material polyhydric alcohol, preferable are pentaerythritol and dipentaerythritol.

In addition, as a monovalent fatty acid to be a raw material, n-butanoic acid, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-methylpropionic acid, 2-methylbutanoic acid, 3- Methylbutanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, 3,5,5-trimethylhexanoic acid, etc., and these may be used alone or in combination of two or more Mix and use.

The viscosity grade of the refrigerator oil varies depending on the type of 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 sealing agent is a liquid compound having a kinematic viscosity at 40 ° C. of more than 180 mm ² / s.

In the case of a hindered type polyol ester oil, a dipentaerythritol-based fatty acid ester (a compound represented by the following chemical formula (3) (wherein R ⁷ and R ^{8 each} have 7 to 8 carbon atoms) as a compressed part sealing agent It is preferable to use an alkyl group). This is because the viscosity tends to be high and refrigerant leakage can be reduced. Dipentaerythritol is not a pure substance because it contains a large amount of pentaerythritol, tripentaerythritol and the like as a raw material, but here, it is referred to as dipentaerythritol-based.

In addition, complex type polyol ester oil (complex ester oil) which is a compression unit sealing agent (a compound represented by the following chemical formula (4) (in the formula, R ⁹ and R ^{10 each} represent an alkyl group having 3 to 9 carbon atoms, R ¹¹ represents an alkyl group having 1 to 9 carbon atoms, n represents a positive number)) is an ester compound in which a polyhydric alcohol, a divalent fatty acid and a monovalent fatty acid are bonded.

Here, preferable polyhydric alcohols as raw materials are, for example, neopentyl glycol, trimethylolpropane and pentaerythritol. In addition, as a monovalent fatty acid to be a raw material, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2 -Ethyl hexanoic acid, iso-octanoic acid, 3,5,5-trimethyl hexanoic acid and the like, and these may be used alone or in combination of two or more. Furthermore, as a divalent fatty acid to be a raw material, there are propane diacid, butane di acid, pentane di acid, hexane di acid, heptane di acid, octane di acid and the like, and these may be used alone or in combination of two or more Use. The above-mentioned dipentaerythritol-based fatty acid ester may be mixed, or a conventional polyol ester oil component may be mixed for viscosity adjustment.

Further, the ethylene-α-olefin copolymer, which is a compressed part sealing agent, is easy to obtain an arbitrary high viscosity, is excellent in shear stability, and preferably has a number average molecular weight of 800 to 4,000. As the α-olefin constituting the ethylene-α-olefin copolymer, one having 3 to 10 carbon atoms is used, and propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-octene, 1 -A decene etc. are mentioned. These α-olefins may be used alone or in combination of two or more. The ethylene content is more preferably 20 to 80 mol%, and may be any of random and block copolymerization with an α-olefin.

There is no problem at all even if a lubricity improver, an antioxidant, an acid scavenger, an antifoamer, a metal deactivator, etc. are added to the above-mentioned refrigerator oil. In particular, since polyol ester oils cause deterioration due to hydrolysis in the presence of water, it is desirable to incorporate an antioxidant and an acid scavenger.

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, since the carbodiimide type compound has extremely high reactivity with fatty acid and captures hydrogen ions dissociated from fatty acid, the effect of suppressing the hydrolysis reaction of the polyol ester oil is very large. Examples of carbodiimide compounds include bis (2,6-isopropylphenyl) carbodiimide. The blending amount of the acid scavenger is preferably 0.05 to 1.0% by weight with respect to the refrigerator oil.

FIG. 1 shows an outline of the air conditioner.

The air conditioner includes an indoor unit 1 and an outdoor unit 2. The indoor unit 1 incorporates an indoor heat exchanger 5. Further, the outdoor unit 2 incorporates a compressor 3, a four-way valve 4, an outdoor heat exchanger 7 and an expansion device 6.

When cooling the room, the high-temperature, high-pressure refrigerant gas adiabatically compressed by the compressor 3 passes through the discharge pipe and the four-way valve 4 and is cooled by the indoor heat exchanger 5 (used as a condensing unit) It becomes a high pressure liquid refrigerant. This refrigerant is expanded by the expansion device 6 (for example, a temperature type expansion valve or other expansion valve) and becomes a low-temperature low-pressure liquid containing a slight amount of gas, leading to the outdoor heat exchanger 7 (used as evaporation means) Then, heat is obtained from the air in the room, and in the state of low temperature gas, it passes through the four-way valve 4 again to the compressor 3. When the room is heated, the flow of the refrigerant is changed in the reverse direction by the four-way valve 4 to cause the reverse action.

As the compressor 3, a scroll compressor was used.

FIG. 2 shows a schematic structure of a scroll compressor.

The compressor 3 includes a fixed scroll member 8 having a spiral wrap 10 vertically provided on the end plate 9, a orbiting scroll member 11 having a wrap 12 substantially the same shape as the stationary scroll member 8, and a orbiting scroll. It includes a frame 16 for supporting the member 11, a crankshaft 13 for pivoting movement of the orbiting scroll member 11, an electric motor 19, and a pressure vessel 17 incorporating these components. The spiral wrap 10 and the wrap 12 face each other and are engaged with each other to form a compression portion.

When the orbiting scroll member 11 is caused to pivot by the crankshaft 13, the compression chamber 14 located at the outermost side among the compression chambers 14 formed between the fixed scroll member 8 and the orbiting scroll member 11 performs a orbiting motion While moving toward the center of the fixed scroll member 8 and the orbiting scroll member 11 while gradually reducing the volume. When the compression chamber 14 reaches near 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. Is discharged.

In the compressor 3, the crankshaft 13 is rotated 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 and The sliding portion with the crankshaft 13 and the sliding bearing 20 are lubricated.

Hereinafter, the configuration of the refrigerating machine oil will be described using examples and comparative examples.

(Examples 1 to 3 and Comparative Examples 1 and 2)
The annual energy consumption efficiency APF was calculated based on Japanese Industrial Standards (JIS C 9612-2005: Room Air Conditioner). In addition, a performance test of the compressor was separately conducted to measure volumetric efficiency from representative conditions. The refrigerant used in the examples is difluoromethane, and a refrigerant oil as a main ingredient and a compression part sealing agent as an additive are shown below.

(Refrigerator oil)
(A) Hindered-type polyol ester oil (mixed fatty acid ester oil of 2-methylbutanoic acid / 2-ethylhexanoic acid based on pentaerythritol / dipentaerythritol): 40 ° C. kinematic 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. kinematic viscosity 64.9 mm ² / s
(Compressor seal agent)
(F) Hindered-type polyol ester oil (a mixed fatty acid ester oil of 2-ethylhexanoic acid / 3,5,5-trimethylhexanoic acid of dipentaerythritol type): 40 ° C. kinematic viscosity 217 mm ² / s
(G) Complex type polyol ester oil (an ester in which neopentyl glycol, a dicarboxylic acid and a monocarboxylic acid are bonded, an ester using adipic acid as the dicarboxylic acid and 3,5,5-trimethylhexanoic acid as the monocarboxylic acid Oil): 40 ° C kinematic viscosity 260 mm ² / s
(H) Ethylene-α-olefin copolymer (trade name: LUCANT HC-40: made by Mitsui Chemicals, Inc., LUCANT is a registered trademark of the company): 40 ° C. kinematic viscosity 380 mm ² / s
In Examples 1 to 3, 5.0% by weight of each of (F), (G) and (H) was blended with the refrigerator oil (A) as a seal for the compression part. In all cases, the kinematic viscosity of the refrigerator oil after blending is around 70 mm ² / s. The refrigerator oil (A) is a refrigerator oil which has a low temperature side critical solution temperature with difluoromethane of −2 ° C. and shows compatibility. As described above, the compatibility of the refrigerant and the refrigeration oil enclosed in the compressor is the reliability of the compressor, such as oil return from the refrigeration cycle to the compressor (retaining the amount of oil inside the compressor) or maintenance of heat exchange efficiency. It is one of the important characteristics in terms of guaranteeing gender. The compatibility evaluation of difluoromethane and a refrigerator oil was measured according to JIS K 2211. In the compatibility evaluation, a graph was created in which the concentration (oil concentration) of the oil mixed with the refrigerant was taken as the abscissa and the dissolution temperature as the ordinate. This graph generally shows the oil concentration dependency of the temperature of separation into two layers, and is a curve having a maximum value. This maximum value was defined as the low temperature side 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 solution temperature is + 9 ° C., and the compression part sealing agent is not blended. This comparative example 1 was taken as the efficiency reference value (APF ratio) 100%. Comparative Example 2 was a combination in which the compressor sealing agent was not blended from Examples 1 to 3. The measurement items were compared between the yearly energy consumption efficiency APF and the volumetric efficiency ratio of the compressor under the four conditions of the heating rating, the heating middle, the cooling rating, and the cooling middle, which are representative operating conditions of the air conditioner. The volumetric efficiency ratio of the APFs of Examples 1 to 3 and Comparative Example 2 was examined with the current apparatus of Comparative Example 1 as 100%.

Table 1 shows the results.

Comparison of Comparative Example 1 and Comparative Example 2 shows that the APF is improved by about 1.0% when difluoromethane is used. This is considered to be because the latent heat of difluoromethane is large and the pressure loss is small, so that the APF is improved. However, when looking at the volumetric efficiency of the compressor, although the APF has been improved, in the compressor using difluoromethane, the volumetric efficiency decreases under any conditions. Since the difluoromethane has a small adiabatic index and a high discharge temperature, the temperature of the compressor also becomes high, and it is easy to cause an overheat loss at the time of suction. Furthermore, since the molecular weight is small and the molecular velocity is high, the refrigerant is likely to leak from the compression unit of the compressor. As a result, volumetric efficiency decreases. On the other hand, as shown in Examples 1 to 3, in the air conditioner in which 5% by weight of the compressed part sealing agent is mixed with difluoromethane and the refrigerator oil (A), the volumetric efficiency of the compressor is improved compared to Comparative Example 2. And the APF of the equipment was also found to increase.

(Examples 4 to 6 and Comparative Examples 3 and 4)
The lubricity of the refrigerator oil was evaluated in Examples 4 to 6. The lubricity of the refrigerator oil was evaluated using a shell type four ball friction and wear tester. The wear scar diameter (average of 3 pieces) and friction of a fixed test piece after testing with a 1/2 inch SUJ2 steel ball as a test piece, load: 280 N, temperature: 120 ° C., rotational speed: 1200 / min, time: 10 min. The coefficients were measured. The refrigerator oil (B) and the compression part sealing agent (F) are the same as those of Examples 1 to 3.

(Refrigerator oil)
(A) Hindered-type polyol ester oil (mixed fatty acid ester oil of 2-methylbutanoic acid / 2-ethylhexanoic acid based on pentaerythritol / dipentaerythritol): 40 ° C. kinematic viscosity 68.7 mm ² / s
About 50 mol% of dipentaerythritol compounding amount
(C) Hindered-type polyol ester oil (mixed fatty acid ester oil of 2-methylbutanoic acid / 2-ethylhexanoic acid based on pentaerythritol / dipentaerythritol): 40 ° C. kinematic viscosity 67.3 mm ² / s
About 35 mol% of dipentaerythritol compounding amount
(D) Hindered-type polyol ester oil (mixed fatty acid ester oil of 2-methylbutanoic acid / 2-ethylhexanoic acid based on pentaerythritol / dipentaerythritol): 40 ° C. kinematic viscosity 66.2 mm ² / s
About 25 mol% of dipentaerythritol blending amount
(E) Hindered-type polyol ester oil (mixed fatty acid ester oil of 2-methylbutanoic acid / 2-ethylhexanoic acid based on pentaerythritol / dipentaerythritol): 40 ° C. kinematic viscosity 65.3 mm ² / s
About 10 mol% of dipentaerythritol compounding amount
As refrigeration oil, (A), (C) and (D) contain 20 mol% or more of dipentaerythritol, and 5.0 wt% of (F) as compression part sealing agent in any refrigeration oil ing.

Table 2 shows the results of evaluating the lubricity of each refrigerator oil.

As shown in Comparative Example 4, when dipentaerythritol is not blended in the refrigerator oil component, the wear trace diameter is large and the friction coefficient is high. On the other hand, as shown in Examples 4 to 6, when 20 weight% or more of dipentaerythritol is blended in the refrigerator oil component, the wear mark diameter and the friction coefficient are suppressed, and the lubricity is excellent. . This is because the adsorption ability of dipentaerythritol to the friction surface is large, the surface energy of the friction surface is reduced, and the effects of reducing the wear resistance and the friction coefficient are obtained. As shown in Comparative Example 3, when the blending amount of dipentaerythritol in the refrigerator oil component is less than 20% by weight, the wear trace diameter is large, the friction coefficient is also high, and sufficient lubricity can not be obtained.

(Examples 7 to 9 and Comparative Examples 5 and 6)
Next, using the refrigerator oil and the compression unit sealing agent whose effects were confirmed in Example 1, the compounding amount of the compressor sealing agent was examined. The measurement items, the measurement method, the refrigerator oil (A) and the compression unit seal agent (F) are the same as those of Examples 1 to 3.

In Examples 7 to 9, (F) was blended in the range of 1 to 30% by weight as a compressor part sealing agent to the refrigerator oil (A). In Comparative Example 5, (F) was set to 0.5% by weight as the compressed part sealing agent, and in Comparative Example 6, 40% by weight of (F) was mixed as the compressed part sealing agent to conduct the test.

The results are shown in Table 3.

As compared with Comparative Example 2, in Examples 7 to 9, the APF is improved by 0.5 to 1.0%. This is due to the effect that the sealability of the compression section of the compressor is improved by the compression section seal agent. On the other hand, as shown in Comparative Example 5, in the embodiment in which (F) is set to 0.5% by weight as the compression part sealing agent, improvement of the volumetric efficiency and APF of the compressor can be obtained compared to Comparative Example 2. Not. In addition, as shown in Comparative Example 6, when 40% by weight of (F) is blended as a sealing agent for the compression section, the kinematic viscosity of the refrigerating machine oil is also greatly increased, and the APF is decreased due to the increase of the viscosity resistance. Do. From this, it is preferable that the blending amount of the compression part sealing agent is in the range of 1.0 to 30% by weight with respect to the refrigeration oil.

From the above results, it is possible to reduce the refrigerant leakage from the compression unit of the compressor, to improve the volumetric efficiency of the compressor, and to improve the annual energy consumption efficiency APF of the air conditioner.

As a compressor, the same effect can be obtained in 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, in addition to a scroll compressor. It confirmed that it could be 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 port, 16: frame, 17: pressure vessel, 18: discharge pipe, 19: electric motor, 20: Slide bearing, 21: Oil hole, 22: Oil reservoir.

Claims

In a compressor provided with a compression chamber having a sliding portion, in which difluoromethane as a refrigerant and refrigeration oil are enclosed,
The refrigeration oil includes a first polyol ester oil represented by the following chemical formula (1) and a second polyol ester oil represented by the following chemical formula (2) (wherein R 1 to R 6 are carbon (3 to 8 alkyl groups) and 20 mol% or more of the second polyol ester oil,
The low temperature side critical solution temperature of the refrigerant and the mixture of the first polyol ester oil and the second polyol ester oil is + 10 ° C. or less,
The refrigerating machine oil further includes a compressed part sealing agent having a kinematic viscosity at 180C of more than 180 mm 2 / s, and the compressed part sealing agent is 1 to 30 parts by weight with respect to 100 parts by weight of the mixture. A compressor characterized in that the kinematic viscosity of the machine oil at 40 ° C. is 30 to 90 mm 2 / s.
The compressed part sealing agent 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 following 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 the number average molecular weight is 800 to The compressor according to claim 1, which is a 4000 ethylene-α-olefin copolymer.
The compressor according to claim 1, wherein the compression chamber is formed by a orbiting scroll member and a fixed scroll member, and the refrigerating machine oil has a kinematic viscosity at 40 属 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.