JP2005248773A - Refrigerating device and refrigerant compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerant compressor and a refrigerating device high in reliability for standing long use in a cold region by using the combination of R410A and ester oil. <P>SOLUTION: In the combination of R410A and ester oil, ester oil of 0°C or lower in critical solution temperature is used to avoid supply of liquid refrigerant to a sliding part caused by a low-temperature flooded phenomenon when a compressor is started in the cold region. Therefore, insufficient lubrication in the sliding part is reduced to provide the refrigerant compressor high in reliability and the refrigerating device having the refrigerant compressor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a refrigerant compressor used in a home heat pump refrigeration cycle using an HFC (hydrofluorocarbon: fluorinated hydrocarbon) refrigerant and a refrigeration apparatus using the compressor.

  Conventionally, HCFC R22 was used as the refrigerant for room air conditioners. However, from the viewpoint of protecting the global environment, we have shifted to HFCs that do not contain chlorine in the molecule. As alternatives, R32A, R125, R134a, or R410A and R407C, which are a mixture of two or more of these, have been used.

  However, HFC refrigerants have poor compatibility with conventional mineral oils, and the oil return to the compressor is reduced in the refrigeration cycle. Therefore, as a refrigerating machine oil having a necessary solubility, a synthetic oil such as an ester oil has been used to ensure oil return without changing the basic configuration of the refrigeration cycle. A compressor using a non-chlorine refrigerant and ester oil is disclosed in Patent Document 1.

Japanese Patent Laid-Open No. 8-120288

The ester oil has one or more fatty acids in the general formula C · (CH ₂ OCOR ² ) ₄ and R2 in the range of 5 to 12 carbon atoms. For room air conditioners, refrigerants of R407C and R410A are used, and refrigeration oils composed of iC ₈ and iC ₉ fatty acids and pentaerythritol represented by the above known examples have been used as refrigeration oils. However, when comparing the heating performance, R410A has better refrigerant COP than R407C, and R410A has become the mainstream refrigerant for room air conditioners. However, compatibility with conventional refrigeration oils deteriorates and the critical solution temperature rises by 20 degrees. Various problems regarding dissolution have become a concern.

  In addition, the viscosity of refrigeration oil was increased due to the decrease in the oil film on the sliding part due to dilution of the refrigerant. Especially in places with low outside air temperature such as in cold districts, the refrigerant is unevenly distributed at the bottom of the compressor due to the low-temperature stagnation phenomenon where refrigerant outside the room air conditioner gathers outside and separates into two layers. Become. Actually, at the time of starting the compressor, the scroll compressor sucks the lubricating oil by the differential pressure oil supply method and the rotary compressor by the mechanical oil supply and sends it to the shaft / bearing portion. At this time, in the refrigerant having a very low viscosity, poor lubrication in which the refrigeration oil is supplied to the shaft / bearing portion occurs, which causes a problem of reliability such as poor start-up and seizure.

  In order to solve the above problems, an object of the present invention is to provide a compressor and a refrigeration apparatus having high reliability in which a low-temperature stagnation phenomenon hardly occurs even in a cold region, for example.

  In order to solve the above-mentioned object, the refrigeration apparatus of the present invention is based on the solubility diagram in which the critical melting temperature is 0 ° C. or less, preferably −20 ° C. or less with the HFC refrigerant composed of R32, R125, R134a and the HFC refrigerant. The combination with the obtained ester oil is provided. Within this refrigerant range, sliding portion lubrication failure due to the low temperature stagnation phenomenon at the start of the compressor to be used can be avoided.

In order to achieve the above low, the compressor of the present invention is an ester oil composed of a mixture of 4 and 9 in which the C number (carbon number) of R2 in the general formula C. (CH ₂ OCOR ² ) ₄ of the fatty acid. In the mixed refrigerant of R32, R125, and R134a, especially in regions where the outside air temperature is below 0 ° C., particularly in regions below −20 ° C., refrigeration oil with greatly improved compatibility and HFC refrigerant coexist. Is.

  As described above, in the refrigeration apparatus and the compressor according to the present invention, it is possible to avoid the supply of the liquid refrigerant to the sliding portion due to the low temperature stagnation phenomenon in a cold region.

  FIG. 1 shows a cross-sectional view of a vertical scroll compressor as a typical refrigerant compressor. Refrigerant compressors used in air-conditioning refrigeration cycles include rotary compressors, scroll compressors, etc. Among them, scroll compressors are in surface contact with the sliding part, so the temperature rise is unlikely to occur instantaneously and the residual rate is low. There is little rise to a temperature at which a high performance acid scavenger reacts sufficiently. In this refrigerant compressor, a compression mechanism section 2 and an electric motor section 3 are housed in a sealed container 1 that also serves as an oil reservoir. The compression mechanism unit 2 includes a turning scroll 4, a fixed scroll 5, a frame 6, a crankshaft 7, and an Oldham ring 8 as main components. A suction pipe 9 communicating with the evaporator of the cycle component is hermetically connected to the sealed container 1.

  The electric motor unit 3 includes a rotor 10 and a stator 11, and a crankshaft 7 made of cast iron is fitted on the rotor 10. The crankshaft 7 has an eccentric portion 12 and a shaft hole 13 having a hollow shaft at the other end. The outer periphery of the frame 6 is fixed to the sealed container 1 and includes a bearing that receives rotation of the crankshaft 7. An orbiting scroll 4 is rotatably attached to the eccentric portion 12 of the crankshaft 7, and an Oldham ring 8 slides in a groove provided on the frame 6 and a groove provided on the base plate on the side opposite to the wrapping scroll 4. Arranged freely. With these configurations, the orbiting scroll revolves without rotating. In addition, refrigeration oil is stored in the oil sump 14 at the bottom, and this refrigeration oil is supplied to the sliding portion.

The refrigerant used in the refrigeration cycle for the heat pump by this refrigerant compressor is HFC R410A or R407C. The refrigerating machine oil in this case is an ester oil having good compatibility with HFC. Conventional refrigeration oils for HFC refrigerants have a viscosity of 2 to 70 cSt at 40 ° C. and a viscosity of 1 to 9 cSt at 100 ° C. The chemical formula of ester oil is C · (CH ₂ OCOR ² ). ₄ - (1) and R ² is included in the range of 5 to 12, as a heat pump cycle has been used as R2 is a mixed acid of iC ₇ acid and iC ₈ acid.

The present invention is intended that could solve various technical challenges associated with dramatically HFC refrigerant miscibility by R ² is to mix iC ₄ acid and iC ₈ acid. Refrigerating machine oil having excellent refrigerant compatibility is supplied to the sliding portion along with the circulation of the refrigerant, and contributes to lubrication of the sliding portion.

  2 (a) is a cross-sectional view of a differential pressure type oil supply mechanism represented by a scroll compressor, and FIG. 2 (b) is a mechanical type equipped with fins that give a turning force to oil in a shaft hole represented by a rotary compressor. The oil supply mechanism sectional view is shown. The refrigerating machine oil 14 is shown in a state of being separated into two layers as described below, the upper layer is a separated refrigerating machine oil 14a having a low specific gravity, and the lower layer is a liquid refrigerant 14b having a heavier specific gravity than the refrigerating machine oil 14a.

  At present, the room air conditioner is mainly a separate type in which the outdoor unit and the indoor unit are separated, particularly in Japan. Separate type outdoor units are installed outdoors even in cold regions. In this outdoor unit, when the outside air temperature becomes 0 ° C. or less when the compressor is stopped, the indoor refrigerant having a high temperature moves to the outdoor unit having a low temperature. At this time, the refrigerating machine oil 14 stored in the compressor causes two-layer separation by the return refrigerant. Refrigerant 14b having a specific gravity heavier than that of ester oil, which is a refrigerating machine oil, accumulates at the bottom of the compressor. When the compressor is activated, the tip of the crankshaft 7 is immersed in the liquid refrigerant 14b, so that the liquid refrigerant 14b passes through the crankshaft 7 and is supplied from the shaft hole 13 to the sliding portion. For this reason, a low-viscosity liquid refrigerant is temporarily supplied to the sliding portion, the lubricating oil film is cut, and the sliding portion is poorly lubricated, which causes a compressor start-up failure.

  This phenomenon occurs only in winter, especially when it is started after the operation is stopped in a very cold region where the outside air temperature reaches -20 ° C. The larger the model, the larger the amount of the enclosed refrigerant, and the larger the amount of the enclosed refrigerant, the more likely to start up. In an air conditioner of 4.0 kw class or higher, the refrigerant amount is 1450 g with respect to 420 ml of refrigerating machine oil, and starting failure is more likely to occur than a model in which the refrigerant amount in a 2.8 kw class air conditioner is 1300 g. However, once started, the separated refrigerating machine oil 14a and liquid refrigerant 14b are agitated and mixed, and the temperature of the compressor rises, so that the refrigerating machine oil is supplied to the sliding portion. Therefore, if only the liquid refrigerant is not supplied to the sliding portion at the start-up stage, the start-up failure of the compressor is improved. Note that the mechanism for supplying refrigerant and refrigerating machine oil from the bottom of the compressor is the same in both the differential pressure type oil supply mechanism and the mechanical oil supply mechanism.

  FIG. 3 shows a basic refrigeration cycle configuration diagram. A refrigeration apparatus including a refrigeration cycle including the refrigerant compressor 15, the condenser 16, the expansion mechanism 17, and the evaporator 18 will be described. The refrigerant compressor 15 compresses the low-temperature and low-pressure refrigerant gas, discharges the high-temperature and high-pressure refrigerant gas, and sends it to the condenser 16. The refrigerant gas sent to the condenser 16 becomes a high-temperature and high-pressure refrigerant liquid while releasing its heat into the air, and is sent to the expansion mechanism 17. The high-temperature and high-pressure refrigerant liquid that passes through the expansion mechanism becomes low-temperature and low-pressure wet steam by the throttling effect and is sent to the evaporator 18. The refrigerant that has entered the evaporator 18 absorbs heat from the surroundings and evaporates, and the low-temperature and low-pressure refrigerant gas that has exited the evaporator 18 is sucked into the compressor 15, and the same cycle is repeated thereafter. In this refrigeration cycle, a room air conditioner or the like requires an intermediate evaporator temperature (−10 ° C. or lower). Here, when the refrigerating machine oil having incompatibility with the refrigerant is used, the refrigerating machine oil separated from the refrigerant by the heat exchanger or the expansion mechanism is accumulated, and the oil return property to the compressor is lowered. A phenomenon occurs in which the amount of oil supplied to the sliding portion is insufficient due to an increase in refrigerating machine oil taken out of the compressor.

  FIG. 4 shows the results of a compatibility test between R410A and ester oil. The lower side of the two-layer separation temperature curve is the separated state, and the highest point is the critical dissolution temperature. It can be said that the lower the critical solution temperature, the better the refrigerating machine oil.

  Here, when the compatibility of R410A and ester oil is compared, the critical dissolution temperature of conventional ester oil A is + 9 ° C., but the critical dissolution temperature of oil B in the present invention is greatly improved to −23 ° C. . This is because the components of the raw fatty acid are different. Oil A was an ester oil composed of a raw fatty acid and pentaerythritol in which the ratio of the C8 isoorganic acid (i-C8) to the C9 isoorganic acid (i-C9) was 50:50. Oil B of the present invention is an ester oil composed of raw fatty acid and pentaerythritol in which the ratio of normal fatty acid (n-C5) having 5 carbon atoms and iso fatty acid (i-C9) having 9 carbon atoms is 30:70, It was found from various experiments. In addition, even if an additive such as an antioxidant, an acid scavenger, an extreme pressure additive, an antifoaming agent, or a corrosion inhibitor is added, this characteristic does not change the refrigerant dissolution characteristic.

  FIG. 5 shows the critical melting temperature of each refrigerant and refrigerating machine oil. Comparison of oil A and oil B reveals that oil B has a lower critical dissolution temperature in any refrigerant except R32.

  FIG. 6 is a refrigerant solubility diagram of Oil B. FIG. 7 is a refrigerant solubility diagram of oil A. Since the main oil B has better refrigerant compatibility than the conventional oil A, for example, when a three-component diagram of R32, R125, and R134a is prepared, the refrigerant-dissolving portion is widened. According to this diagram, it can be seen that both R410A and R407C showed refrigerant dissolution at −20 ° C. or less, and the two-layer separation was eliminated. Also, the mixing ratio of the three components is different, for example R407A (R32 / 125 / 134a = 20/40 / 40wt%), R407B (R32 / 125 / 134a = 10/70 / 20wt%), R407D (R32 / 125 / 134a = 15/15 / 70wt%), R407E (R32 / 125 / 134a = 25/15 / 60wt%), R410B (R32 / 125 = 45 / 55wt%), etc. You can see that Moreover, since the solubility of the refrigerant | coolant with respect to the ester oil used by this invention differs for every refrigerant | coolant, it is estimated that the part different from an enclosed refrigerant composition also exists in a cycle. However, even in that case, it can be said that it is sufficiently within the dissolution range.

  FIG. 8 shows the mixing ratio of oil B / oil A and the critical melting temperature of R410A. It can be seen that when oil A having poor compatibility with R410A and oil B having excellent compatibility are mixed, the critical solution temperature also varies depending on the mixing ratio. When oil A and oil B are blended, the critical dissolution temperature is 0 ° C or lower if the ratio of oil B exceeds 25%, and the critical dissolution temperature of 0 ° C or lower is also found for other refrigerating machine oils. Can be satisfied.

  Furthermore, in the case where a refrigerant of −20 ° C. or lower is used for a cold district, this can be achieved by keeping the mixing ratio of the oil B at a ratio higher than 90%.

  As described above, in the refrigerating apparatus and compressor of the present invention equipped with the refrigerating machine oil used in the present invention described above, the composition of the HFC refrigerant represented by R410A and R407C is P134a (R134a in FIG. = 100%), A0 (R32 / R134a = 65/35), B0 (R32 / R125 = 23/77), P125 (R125 = 100%), and the combination of the ester oil of the present invention and critical dissolution By using ester oil having a temperature of 0 ° C. or lower, it is possible to avoid supply of liquid refrigerant to the sliding portion due to a low-temperature stagnation phenomenon in a cold region. Therefore, the occurrence of poor lubrication of the sliding portion can be reduced, and a highly reliable refrigerant compressor and refrigeration apparatus can be provided.

  Furthermore, in extremely cold regions where the outside air refrigerant is -20 ° C. or lower, P134a (R134a = 100%), A-20 (R32 / R134a = 35/65), B-20 (R32 / R125) shown in FIG. = 52/48), the mixed refrigerant in the range of P125 (R125 = 100%) has the effect of improving the reliability of the compressor and heat pump refrigeration cycle by improving the compatibility.

It is sectional drawing of the vertical scroll compressor which is one Example of this invention. It is sectional drawing of the oil supply mechanism of a compressor. It is a refrigerating cycle block diagram which is one Example of this invention. It is explanatory drawing of the compatibility test result of R410A and ester oil. It is a table | surface which shows the critical solution temperature with respect to each refrigerant | coolant. 2 is a refrigerant solubility diagram of Oil B. It is a refrigerant solubility diagram of conventional oil. It is a figure which shows the relationship between the ratio of oil B / oil A, and the critical solution temperature of R410A.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Compression mechanism part 3 Electric motor 4 Orbiting scroll 5 Fixed scroll 6 Frame 7 Crankshaft 8 Oldham ring 9 Suction pipe 10 Stator 11 Rotor 12 Eccentric part 13 Shaft hole 14 Refrigerator oil 15 Refrigerant compressor 16 Condenser 17 Expansion mechanism 18 Evaporator.

Claims (7)

A refrigerant compressor for use in a refrigeration cycle, a motor having a rotor and a stator in a sealed container for storing refrigerator oil, a rotating shaft fitted to the rotor, and the rotating shaft through the rotating shaft In a refrigerant compressor containing a compression mechanism connected to a motor, the critical melting temperature of at least R32, R125, R134a alone or a mixed refrigerant of two or more and the refrigerant is 0 ° C. or less, These are used as refrigeration oils within the refrigerant composition range specified by P134a (R134a = 100%), A0 (R32 / R134a = 65/35), B0 (R32 / R125 = 23/77), P125 (R125 = 100%) A refrigerant compressor using ester oil synthesized from pentaerythritol and fatty acid whose viscosity with refrigerant is 40 ° C 56 to 72 mm ² / s. Refrigerant composition is P _134a , A- ₂₀ (R32 / R134a = 35/65), B-20 (R32 / R125 = 52/48) P ₁₂₅ The refrigerant compressor according to claim 1, wherein the refrigerant compressor has a temperature of not higher than ° C.   A refrigerating apparatus comprising the refrigerant compressor according to claim 1, wherein the refrigerating apparatus includes at least a compressor, a condenser, an expansion mechanism, an evaporator, and a refrigerant pipe connecting them. 40 ° C composed of raw fatty acid and pentaerythritol whose mass ratio of 30% normal fatty acid (n-C5) having 5 carbon atoms and 70% iso fatty acid (i-C9) having 9 carbon atoms is approximately 25 to 35:75 to 65 A refrigerating apparatus using a refrigerating machine oil based on an ester oil (VG68) having a viscosity of 56 to 72 mm ² / s.   A refrigerating apparatus, wherein the ester oil described in claim 3 is mixed with 5 to 95% of another ester oil, and the critical solution temperature for R410A is 0 ° C or lower.   The refrigeration according to claim 3, 4, or 5, wherein the refrigerating machine oil is ester oil obtained by adding at least one additive such as an antioxidant, an acid scavenger, an extreme pressure additive, an antifoaming agent, and a corrosion inhibitor. apparatus. 6. The refrigeration apparatus according to claim 5, wherein 0.05 to 3.0% by mass of one or more kinds of carbodiimides and epoxies is added as the acid scavenger of claim 5.

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