JP6011861B2 - Compressor and refrigeration cycle apparatus using the same - Google Patents

Description

  The present invention relates to a compressor using a refrigerant mainly composed of a hydrofluoroolefin having a low global warming potential and having a carbon double bond, and a refrigeration cycle apparatus using the same.

  The refrigerant used in the compressor and the refrigeration cycle apparatus using the compressor has shifted to an HFC (hydrofluorocarbon) system (hereinafter referred to as “HFC-based refrigerant”) having an ozone layer depletion coefficient of zero.

  A compressor and a refrigeration cycle apparatus using an HFC refrigerant will be described with reference to FIGS. 7 to 9 (see, for example, Patent Documents 1 and 2).

  FIG. 7 is a longitudinal sectional view of a rotary compressor described in Patent Document 1 that uses an HFC-based refrigerant.

  A stator 2 a of the motor 2 is fixed to the upper part of the hermetic container 1. A compression mechanism 5 having a shaft 4 driven by the rotor 2 b of the motor 2 is fixed to the lower part of the hermetic container 1. A bearing 7 is fixed to the upper end of the cylinder 6 of the compression mechanism 5 with a bolt or the like, and a bearing 8 is fixed to the lower end of the cylinder 6 with a bolt or the like. A piston 9 is disposed in the cylinder 6. The eccentric part 4a of the shaft 4 is inserted in the piston 9, and the piston 9 rotates eccentrically by this eccentric part 4a.

  Further, R410A (mixture of HFC32 and HFC125) is sealed in the sealed container 1 as a refrigerant. A refrigerating machine oil 103 having a polarity, such as polyol ester (POE) or polyvinyl ether (PVE), which is compatible with the refrigerant, is stored at the bottom of the sealed container 1.

  FIG. 8 is a cross-sectional view of a rotary compressor described in Patent Document 1 that uses an HFC-based refrigerant. When the vane 10 partitions the space between the cylinder 6 and the piston 9, a suction chamber 13 into which the refrigerant is sucked and a compression chamber 14 into which the refrigerant is compressed are formed.

  About the rotary compressor comprised as mentioned above, the operation | movement and an effect | action are demonstrated.

  First, the refrigerant is sucked into the suction chamber 13 through the suction port 12 provided in the cylinder 6. The refrigerant in the compression chamber 14 is compressed by the leftward rotation (in the direction of the arrow) of the piston 9, passes through the discharge notch 15, and is discharged into the sealed container 1 through the discharge port (not shown). The The compressed refrigerant discharged into the hermetic container 1 passes through the gap of the motor 2 and is discharged to the outside of the hermetic container 1 through the discharge pipe 16 disposed at the upper part of the hermetic container 1. At that time, the mist of the refrigerating machine oil 103 existing around is also discharged together.

  Next, a basic refrigeration cycle apparatus having a rotary compressor 20 that sucks and compresses an HFC refrigerant described in Patent Document 2 will be described with reference to FIG.

  As shown in FIG. 9, the rotary compressor 20 compresses the low-temperature / low-pressure refrigerant gas and discharges the high-temperature / high-pressure refrigerant gas toward the condenser 21. The HFC-based refrigerant gas sent to the condenser 21 releases its heat into the air, becomes a high-temperature / high-pressure refrigerant liquid, and is sent to an expansion mechanism (for example, an expansion valve or a capillary tube) 22. The high-temperature and high-pressure refrigerant liquid that passes through the expansion mechanism 22 becomes low-temperature and low-pressure wet steam due to the throttling effect, and is sent to the evaporator 23. The refrigerant that has entered the evaporator 23 absorbs heat from the surroundings and evaporates. The low-temperature and low-pressure refrigerant gas exiting the evaporator 23 is sucked into the rotary compressor 20. Such a cycle is repeated.

  By the way, this HFC-based refrigerant is difficult to be decomposed in the atmosphere and has a very high global warming potential (hereinafter referred to as GWP), which has become a problem in recent years from the viewpoint of protecting the global environment. Yes. Thus, studies are being made on refrigerants mainly composed of hydrofluoroolefins having a low GWP and having a carbon double bond.

JP 11-236890 A JP-A-8-240362

  However, although the refrigerant mainly composed of hydrofluoroolefin having a carbon double bond has a low global warming potential (GWP), it is more easily decomposed than HFC refrigerant and has a problem in stability.

  For this reason, for example, the heat generated in the sliding portion of the rotary compressor such as the tip 10a of the compressor vane 10 and the outer peripheral surface of the piston 9 causes decomposition and polymerization of the refrigerant and the refrigerating machine oil, resulting in generation of sludge. There are things to do. Due to the sludge, there is a possibility that the rotary compressor breaks down and the sludge is clogged in the refrigeration cycle apparatus.

  Therefore, the inventor added an antioxidant or the like to the refrigerating machine oil in order to suppress the generation of the reaction product of the refrigerant. As a result, it has been found that the decomposition of the refrigerant is suppressed and the generation of the fluorine-based compound contained in the reaction product is also suppressed. It has been confirmed that this fluorine-based compound is adsorbed on sliding portions such as the tip of the vane and the outer peripheral surface of the piston to improve the wear resistance. Therefore, if the production of such a fluorine-based compound is suppressed, wear of the sliding portion proceeds, and the reliability of the compressor, that is, the refrigeration cycle apparatus using the compressor may not be maintained.

  As a countermeasure, the inventor considered adding an antiwear agent such as an extreme pressure additive to the refrigerator oil. However, when the inventor uses a refrigerant mainly composed of a hydrofluoroolefin having a carbon double bond, it is difficult to obtain an anti-wear effect only by adding an anti-wear agent to the refrigerating machine oil. Found by. Therefore, it is an important issue to increase the effect of the antiwear agent and maintain the reliability with the compressor, that is, the refrigeration cycle apparatus.

  Therefore, the present invention provides a highly reliable compressor that can suppress the generation of sludge by suppressing the decomposition and polymerization of refrigerant and refrigeration oil and maintain the wear resistance of the compressor, and a refrigeration using the same. An object is to provide a cycle device.

  In order to achieve the above object, the present invention is configured as follows.

According to one aspect of the present invention, there is provided a compressor used in a refrigeration cycle apparatus, which does not have a single refrigerant of a hydrofluoroolefin having a carbon double bond or a double bond of the hydrofluoroolefin and carbon. As the sliding part exposed to the mixed refrigerant and the refrigerating machine oil, the mixed refrigerant containing hydrofluorocarbon is used, the refrigerating machine oil containing the additive and the anti-wear agent for suppressing deterioration of the refrigerating machine oil is used , and a piston and a vane mutually slide relative to each other, said vanes being a ceramic coating with a hardness of HV1500～2000, said piston, Ru with a hardness of HRC47～55, the compressor is provided.

  According to another aspect of the present invention, the refrigeration cycle apparatus includes the above-described compressor, a condenser, an expansion mechanism, and an evaporator, and forms a refrigeration cycle that compresses, condenses, expands, and evaporates the refrigerant. Is provided.

  According to the present invention, decomposition and polymerization of the refrigerant and the refrigerating machine oil are suppressed, and thereby generation of sludge is suppressed. Further, the wear resistance of the sliding portion of the compressor, for example, the vane and the piston can be maintained. As a result, the reliability of the compressor and the refrigeration cycle apparatus using the compressor can be ensured.

These aspects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiments with reference to the accompanying drawings. In this drawing,
Configuration diagram of a refrigeration cycle apparatus according to an embodiment of the present invention Vertical sectional view of a rotary compressor according to an embodiment Cross-sectional view of a rotary compressor according to an embodiment The figure which shows the characteristic correlation of operating time, piston wear amount, and total acid value of refrigeration oil about each of different refrigeration oil concerning an embodiment. The figure which shows the characteristic correlation of an operating time, piston wear amount, and refrigeration oil total acid value about each of the different piston which concerns on embodiment. The figure which shows the characteristic correlation of piston abrasion amount and refrigeration oil total acid value with respect to piston surface hardness based on Embodiment Longitudinal sectional view of a conventional rotary compressor Cross-sectional view of a conventional rotary compressor Configuration diagram of conventional refrigeration cycle equipment

  The compressor according to the present invention is a compressor used in a refrigeration cycle apparatus, and is a single refrigerant of hydrofluoroolefin having a carbon double bond or a hydrofluorine having no carbon double bond. A mixed refrigerant containing fluorocarbon is used, the refrigerator oil containing an additive for suppressing deterioration of the refrigerator oil and an antiwear agent is used, and the HRC (Rockwell Hardness C) is exposed to the mixed refrigerant and the refrigerator oil. -Scale: Rockwell hardness C scale) It has a sliding part with a hardness of 47-55. According to such a compressor, the decomposition and polymerization of the refrigerant and the refrigerating machine oil are suppressed, thereby suppressing the generation of sludge. Further, it is possible to maintain the wear resistance of the sliding portion of the compressor, for example, the piston and vane that slide with each other. As a result, the reliability of the compressor can be ensured.

  The vanes may be made from an iron-based material and nitrided, or made from sintered alloy steel and subjected to a sintering process and a quenching process. When the vane is made of an iron-based material and is nitrided, the vane can be made at a low cost. As a result, the compressor can be mass-produced. Further, when the vane is made of sintered alloy steel and subjected to sintering treatment and quenching treatment, a hard structure in which W, Mo, Cr, and V-based carbides are dispersed in a fine martensite structure can be obtained. it can.

  The vanes are preferably made from high speed tool steel. Thereby, the vane excellent in abrasion resistance can be obtained.

  The vanes may be ceramic coated. The ceramic coating can suppress an increase in temperature due to friction between the tip of the vane and the outer peripheral surface of the piston, and as a result, decomposition of the refrigerant can be suppressed. Moreover, the polarity of the tip of the vane is maintained by the ceramic coating, and an extreme pressure layer (abrasion inhibitor film) is formed on the surface of the tip of the vane. Thereby, abnormal wear of the vane can be suppressed.

  The surface of the vane may be coated with a nitride or carbide of Ti (titanium), V (vanadium), Ta (tantalum), W (tungsten), or Nb (niobium) by a ceramic coating. As a result, the wear resistance of the vane is improved and the sliding resistance is reduced. Thereby, the temperature rise by friction can be suppressed and decomposition | disassembly and superposition | polymerization of a refrigerant | coolant and refrigerating machine oil can be suppressed.

  The ceramic coating thickness at the tip of the vane in contact with the piston is preferably 5-15 μm. Thereby, the reliability of the front-end | tip part of the vane which slides on severe sliding conditions is securable.

  The ceramic coating is preferably applied only to the tip of the vane. Since the ceramic coating is applied only to the tip of the vane that slides under severe sliding conditions, the coating cost can be reduced.

  The vane may be made from a ceramic material. Thereby, the temperature rise by friction can be suppressed between the front-end | tip part of a vane, and a piston outer peripheral surface, As a result, decomposition | disassembly of a refrigerant | coolant and refrigerator oil can be suppressed. In addition, the polarity of the tip of the vane is maintained, and an extreme pressure layer (abrasion inhibitor film) is formed on the surface of the tip of the vane. Thereby, abnormal wear of the vane can be suppressed.

  The piston may be made from cast iron. When the piston is made of cast iron, the surface hardness can be effectively increased by quenching and tempering, and carbon contained in the cast iron functions as a solid lubricant during sliding. Thereby, the wear resistance of the piston is improved and the temperature rise due to friction can be suppressed, and as a result, the decomposition and polymerization of the refrigerant and the refrigerating machine oil are suppressed. That is, the generation of sludge can be suppressed. Moreover, a piston can be produced cheaply by using cast iron. As a result, the compressor can be mass-produced.

  Cast iron, which is a material of the piston, preferably contains 0.4 to 1.2 wt% chromium and 0.15 to 0.7 wt% molybdenum. Thereby, the carbide | carbonized_material in cast iron is stabilized, a cast iron structure | tissue becomes dense, and a mechanical property improves. Further, the sliding surface of the piston can be effectively finished to a desired surface property.

  The cast iron that is the material of the piston preferably contains 0.15 to 0.4 wt% of nickel. Thereby, the coarsening of the graphite is suppressed, the cast iron structure can be made dense, and the mechanical properties of the cast iron are improved. Further, the sliding surface of the piston can be effectively finished to a desired surface property. Furthermore, crystallization is suppressed by promoting graphitization, and thereby good machinability can be obtained. As a result, the productivity of the piston, that is, the productivity of the compressor is improved.

  The surface of the vane and the surface of the piston preferably have a surface roughness of Ra 0.4 μm or less. As a result, the familiarity period between the surface of the vane and the surface of the piston is shortened, and a uniform extreme pressure layer (antiwear film) is formed on the surface at an early stage. That is, the period of the high temperature state in which the refrigerant and the refrigerating machine oil are likely to be decomposed and polymerized is shortened. As a result, the generation of sludge can be suppressed,

  The refrigerant contains at least one of tetrafluoropropene or trifluoropropene which is a kind of hydrofluoroolefin, and may have a global warming potential of 5 or more and 750 or less, preferably 5 or more and 350 or less. Such a refrigerant can provide a compressor with a small environmental load.

  The refrigerant is mainly composed of tetrafluoropropene or trifluoropropene, which is a kind of hydrofluoroolefin, and difluoromethane and pentafluoroethane preferably have a global warming potential of 5 or more and 750 or less, preferably 5 or more and 350 What was mixed so that it might become the following may be sufficient. Such a refrigerant can provide a compressor with a small environmental load.

  As refrigerating machine oils, (1) polyoxyalkylene glycols, (2) polyvinyl ethers, (3) poly (oxy) alkylene glycols or their monoether and polyvinyl ether copolymers, (4) polyol esters and polycarbonates (5) Synthetic oil mainly containing alkylbenzenes, or (6) Synthetic oil mainly containing α-olefins may be used. According to such refrigerating machine oil, the decomposition and polymerization of the refrigerant and the refrigerating machine oil are suppressed, thereby suppressing the generation of sludge. Further, it is possible to maintain the wear resistance of the sliding portion of the compressor, for example, the piston and vane that slide with each other. As a result, the reliability of the compressor can be ensured.

  The refrigeration cycle apparatus according to the present invention includes the above-described compressor, a condenser, an expansion mechanism, and an evaporator, and forms a refrigeration cycle that compresses, condenses, expands, and evaporates the refrigerant. According to such a refrigeration cycle apparatus, the decomposition and polymerization of the refrigerant and the refrigeration oil are suppressed, thereby suppressing the generation of sludge. Further, it is possible to maintain the wear resistance of the sliding portion of the compressor, for example, the piston and vane that slide with each other. As a result, the reliability of the refrigeration cycle apparatus can be ensured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

(Embodiment)
FIG. 1 shows a basic refrigeration cycle apparatus according to an embodiment of the present invention. This refrigeration cycle apparatus has a compressor 120 as shown in FIG. The compressor 120 compresses the low-temperature / low-pressure refrigerant gas and discharges the high-temperature / high-pressure refrigerant gas toward the condenser 121. The refrigerant gas sent to the condenser 121 becomes a high-temperature and high-pressure refrigerant liquid while releasing its heat into the air, and is sent to an expansion mechanism (for example, an expansion valve or a capillary tube) 122. The high-temperature and high-pressure refrigerant liquid that passes through the expansion mechanism 122 becomes low-temperature and low-pressure wet steam by the throttling effect and is sent to the evaporator 123. The refrigerant that has entered the evaporator 123 absorbs heat from the surroundings and evaporates. Then, the low-temperature and low-pressure refrigerant gas exiting the evaporator 123 is sucked into the rotary compressor 120. Such a cycle is repeated.

  A compressor 120 used in such a refrigeration cycle apparatus is shown in FIGS. The compressor 120 shown in FIGS. 2 and 3 is a rotary compressor. The rotary compressor 120 has a stator 102 a of a motor 102 fixed to the upper part of the hermetic container 101. A compression mechanism 105 having a shaft 104 driven by the rotor 102 b of the motor 102 is fixed to the lower portion of the sealed container 101. A bearing 107 is fixed to the upper end of the cylinder 106 of the compression mechanism 105, and a bearing 108 is fixed to the lower end with a bolt or the like. A piston 109 is disposed in the cylinder 106. An eccentric portion 104a of the shaft 104 is inserted into the piston 109, and the piston 109 rotates eccentrically by the eccentric portion 104a. A vane 110 is inserted into the vane groove 106 a of the cylinder 106, and a vane spring 111 is installed on the back portion 110 b of the vane 110. The vane spring 111 urges the vane 110 so that the tip 110 a of the vane 110 abuts on the outer peripheral surface of the piston 109.

  In the refrigeration cycle apparatus including the compressor 120, tetrafluoropropene (hereinafter, referred to as “HFO1234yf refrigerant”), which is a kind of hydrofluoroolefin having a carbon double bond, is enclosed. A refrigerating machine oil 103 containing a base oil compatible with the HFO 1234yf refrigerant is stored at the bottom of the sealed container 101. It is possible to use the refrigerating machine oil 103 mainly composed of at least one of the base oils of polyol ester, polyvinyl ether and polyalkylene glycol. In the case of the present embodiment, the refrigerating machine oil 103 containing only polyol ester as a main component is used.

  The polyol ester refrigerating machine oil 103 is synthesized by a dehydration reaction between a polyhydric alcohol and a saturated or unsaturated fatty acid. As the polyhydric alcohol that contributes to the viscosity of the refrigerating machine oil 103, neopentyl glycol, pentaerythritol, dipentaerythritol and the like are used. As saturated fatty acids, straight chain fatty acids such as hexanoic acid, heptanoic acid, nonanoic acid and decanoic acid, and branched chain fatty acids such as 2-methylhexanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid Is used. Polyol ester oils containing linear fatty acids have good sliding properties but poor hydrolyzability, and ester oils containing branched chain fatty acids have the advantage of being difficult to hydrolyze, although they have slightly poor sliding properties. Should be noted.

  Further, the refrigerating machine oil 103 of the present embodiment is added with a sulfur-based extreme pressure additive for preventing wear and an additive for suppressing deterioration of the refrigerating machine oil. Various additives such as an antioxidant such as dibutyl-p-cresol, an acid scavenger such as an epoxy-containing compound, a metal deactivator, and an antifoaming agent are used as additives for suppressing deterioration of the refrigerating machine oil. It is selectively added to the machine oil 103.

  Examples of sulfur-based extreme pressure additives that prevent wear include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dialkyl polysulfides, dibenzyl disulfides, oligomer polysulfides, and the like. These sulfur-based extreme pressure additives preferably have 3 or less sulfur bridges. When the sulfur cross-linking length is 4 or more, sulfur is likely to be released into the refrigerating machine oil 103, which may corrode copper used in piping or the like in the refrigeration cycle.

  Some metal deactivators have a function of preventing copper pipe corrosion of sulfur, and benzotriazoles can be used as such metal deactivators. In order to improve the extreme pressure effect, a phosphorus-based extreme pressure additive may be used. As the phosphorus-based extreme pressure additive, phosphate esters such as tricresyl phosphate and triphenyl phosphate, phosphite esters, amine salts of acidic phosphate esters, and the like can be used. Preferably, acidic phosphates such as tricresyl phosphate and triphenyl phosphate, which are excellent in compatibility with the refrigerating machine oil 103, are preferable. The phosphorus-based extreme pressure additive has a higher effect of preventing wear under a low load than the sulfur-based extreme pressure additive. Therefore, the combined use of a sulfur-based extreme pressure additive and a phosphorus-based extreme pressure additive is optimal for a compressor of a refrigeration cycle apparatus that is operated in a wide frequency range by inverter control.

  As described above, in the rotary compressor 120 according to the present embodiment, the piston 109 continues to push the front end portion 110a of the vane 110 while rotating eccentrically in the cylinder 106, whereby the refrigerant is sucked, compressed, and discharged. The Therefore, the tip portion 110a of the vane 110 serving as the sliding portion has higher hardness than the portion other than the tip portion 110a of the vane 110 by forming a coating film. Specifically, examples of the coating film include CrN (chromium nitride), DLC (diamond like carbon (diamond-like carbon)), TiN (titanium nitride), and the like. The coating film on the tip portion 110a of the vane 110 has a polarity maintaining effect, and is configured by, for example, graphite or the like having connected benzene rings dispersed therein. When the refrigeration oil 103 approaches, the coating film is polarized by being induced by the polarity of the refrigeration oil 103, and the coating film has polarity. As a result, the extreme pressure additive in the refrigerating machine oil 103 is adsorbed and an extreme pressure layer (extreme pressure additive film) is formed on the coating film. The extreme pressure layer formed on the sliding portion in this way makes it possible even under severe sliding conditions (for example, when the compressor starts operating at maximum capacity after being left for half a day at an outside temperature of −10 ° C. or lower). ), The lubricating oil in the sliding portion is not insufficient, and abnormal wear of the sliding portion is suppressed.

  The operation and action of the refrigeration cycle apparatus and the rotary compressor configured as described above will be described below with reference to FIGS.

  First, the refrigerant (HFO 1234yf refrigerant) is drawn into the suction chamber 113 through the suction port 112 provided in the cylinder 106. Further, the refrigerant in the compression chamber 114 constituted by the vane 110, the piston 109, and the cylinder 106 is compressed by the leftward rotation (arrow direction) of the piston 109, passes through the discharge notch 115, and is discharged to the discharge port (see FIG. (Not shown) is discharged into the sealed container 101. The compressed refrigerant discharged into the sealed container 101 passes through the gap of the motor 102 and is discharged into the refrigeration cycle via the discharge pipe 116 disposed at the upper part of the sealed container 101. At that time, the mist of the refrigerating machine oil 103 existing around is also discharged together. As described above, the refrigerant discharged during the refrigeration cycle sequentially passes through the condenser 121, the expansion mechanism 122, and the evaporator 123, and is again sucked into the suction chamber 113 through the suction port 112 of the compressor. .

  Here, in the configuration of the rotary compressor 120, the sliding parts with the severest sliding conditions are the tip part 110 a of the vane 110 and the outer peripheral surface of the piston 109 that are in contact with each other. In addition to the urging force of the vane spring 111, a high discharge pressure acts on the back part 110 b of the vane 110. For this reason, a large force corresponding to the differential pressure with respect to the pressure in the cylinder 106 acts on the vane 110. The region between the front end portion 110a and the outer peripheral surface of the piston 109 is in a state of mixed lubrication or boundary lubrication.

  In view of such points, in the present embodiment, the vane 110 is made of steel such as SKH, SKD, SUS, or SCM, and is nitrided. Further, a ceramic coating film such as CrN or DLC is formed on the surface of the tip 110a of the vane 110 by a PVD processing method. Thereby, the surface of the front-end | tip part 110a of the vane 110 is equipped with the hardness of about HV 1500-2000, and the surface roughness of about the front-end | tip Ra 0.2micrometer.

  On the other hand, the piston 109 is a cast iron containing 0.7 to 1.0 wt% of chromium (Cr), 0.2 to 0.4 wt% of molybdenum (Mo), and 0.2 to 0.4 wt% of nickel (Ni). (Hereinafter referred to as “monichro cast iron”) and has a surface hardness of about HRC 47 to 55 by quenching, sub-zero, tempering, cooling, and the like. The reason why the surface hardness is HRC 47 to 55 will be described later. Further, since there are microscopic concave portions of graphite on the outer peripheral surface of the piston 109 which is a sliding surface, the flat portion excluding the micro concave portions on the outer peripheral surface of the piston 109 has a surface roughness of about Ra 0.2 μm. It has been finished.

  Next, an example of a result of an actual machine operation test of a refrigeration cycle apparatus incorporating the rotary compressor 120 will be described.

  The vane 110 used for the test is made of high-speed tool steel (SKH51), and a CrN ceramic coating film having a surface hardness of about HV1800, a film thickness of 5 μm, and a surface roughness Ra of 0.2 μm is formed on the tip 110a. Is formed. The piston 109 used for the test contains 0.7 to 1.0 wt% of chromium (Cr), 0.2 to 0.4 wt% of molybdenum (Mo), and 0.2 to 0.4 wt% of nickel (Ni). It is made from the cast iron black and has a surface roughness of about HRC50. HFO1234yf refrigerant was used for the test. On the other hand, a plurality of types of refrigerating machine oil 103 were prepared. Specifically, the refrigerating machine oil of Comparative Example 1 which is only a polyol ester, the refrigerating machine oil of Comparative Example 2 which is a polyol ester containing an acid scavenger, and an example which is a polyol ester containing an acid scavenger and an antiwear agent. 1 refrigerator oil was prepared. Further, three rotary compressors 120 were prepared for each of Comparative Example 1, Comparative Example 2, and Example 1. In each of Comparative Example 1, Comparative Example 2, and Example 1, 300 hours for the first rotary compressor 120, 1000 hours for the second rotary compressor 120, and a third rotary compressor An overload operation test was performed on 120 for 2000 hours. After the test, the wear amount of the piston 109 and the total acid value of the refrigerating machine oil 103 were measured for each rotary compressor 120.

  The total acid value is the number of milligrams (mg) of potassium hydroxide required to neutralize all acidic components contained in 1 g of the sample. The acid value is an index widely used for knowing the degree of oxidation during use of the lubricating oil or for evaluating the lubricating oil after an oxidation test and a practical test. Here, the total acid value corresponds to the amount of hydrofluoric acid that is a decomposition product of the refrigerant and the amount of carboxylic acid that is the decomposition product of the refrigerating machine oil 103. Furthermore, the total acid value also corresponds to the amount of sludge generated by decomposition and polymerization of refrigerant and refrigerating machine oil.

  4 (a) and 4 (b) show the characteristic correlation of the operating time, the piston wear amount, and the total acid value of the refrigeration oil for Example 1, Comparative Example 1, and Comparative Example 2, respectively. The horizontal axis indicates the operation time, the vertical axis in FIG. 4 (a) indicates the amount of piston wear, and the vertical axis in FIG. 4 (b) indicates the total acid value.

  As shown in FIG. 4B, in the case of the refrigerating machine oil 103 only of the polyol ester of Comparative Example 1, a rapid increase in the acid value was confirmed. This is because HFO1234yf refrigerant (a refrigerant mainly composed of hydrofluoroolefin having a carbon double bond), which is less stable than HFC refrigerant, is easily decomposed, and the acid generated by the decomposition causes deterioration of the refrigerating machine oil. It can be estimated that it was promoted.

  As a countermeasure, an acid scavenger was added to the polyol ester, that is, in the case of the refrigerating machine oil of Comparative Example 2, an increase in acid value was suppressed. However, as shown in FIG. 4A, the amount of wear in Comparative Example 2 was increased compared to Comparative Example 1 containing only the polyol ester. This is because when the oxidant is added to the polyol ester as in Comparative Example 2, the acid scavenger can suppress the increase in the acid value of the refrigerating machine oil, but at the same time, the formation of a fluorine-based reactant that is a decomposition product of the refrigerant. This is presumed to be suppressed. It is presumed that the fluorine-based reactant adheres to the sliding portion of the compressor and has an effect of reducing wear of the sliding portion as a solid lubricant.

  On the other hand, from the results of Example 1, when an acid scavenger and an antiwear agent are added to the polyol ester, the acid scavenger suppresses the increase in the acid value of the refrigerating machine oil (prevents the deterioration of the refrigerating machine oil). In addition, it has been found that the wear amount of the sliding portion is reduced by the wear inhibitor.

  Next, the result of a further test using a plurality of different pistons 109 will be described.

  Table 1 shows details of the pistons 109 of Example 2, Comparative Example 3, and Comparative Example 4 used in the test. The refrigerant used for the test is HFO1234yf refrigerant. In the test, in order to exclude the influence of the refrigerating machine oil 103, the refrigerating machine oil 103 of only polyol ester was used. In addition, the same tendency is confirmed as a result of the test even when various additives are added to the refrigerating machine oil 103.

  The piston 109 of the second embodiment is the same as that described with reference to FIGS. The piston 1109 of Example 2 contains 0.7 to 1.0 wt% of chromium (Cr), 0.2 to 0.4 wt% of molybdenum (Mo), and 0.2 to 0.4 wt% of nickel (Ni). It is made from the cast iron black and has a surface hardness of about HRC50. Further, the outer peripheral surface of the piston 109 is finished so that the flat portion excluding the minute concave portion has a surface roughness of about Ra 0.2 μm.

  The material of the piston 109 of Comparative Example 3 is the same as that of Example 2, but unlike Example 2, it has a surface hardness of about HRC59. Further, the surface roughness is about Ra 0.2 μm.

  The material of the piston 109 of Comparative Example 4 is the same as that of Example 2 and has a surface hardness of about HRC41. Further, the surface roughness is about Ra 0.2 μm.

  FIG. 5A and FIG. 5B show the characteristic correlation of the operating time, the piston wear amount, and the total acid value of the refrigeration oil for Example 2, Comparative Example 3, and Comparative Example 4, respectively. The horizontal axis indicates the operation time, the vertical axis in FIG. 5 (a) indicates the amount of piston wear, and the vertical axis in FIG. 5 (b) indicates the total acid value.

  First, the amount of wear of the piston 109 shown in FIG.

  In all of Example 2, Comparative Example 3, and Comparative Example 4, the progress of wear is fast at first, and the progress of wear tends to be slow as the operation time elapses. In general, as shown in FIG. 5A, wear in a region where wear progresses rapidly (region where the inclination is large) is called initial wear, and wear in a region where the inclination is small is called steady wear. The initial wear is a period in which these microprotrusions disappear when the microprotrusions existing on the surface collide with each other, and is also called a familiar process. When the conforming process is finished, the surface becomes smooth to some extent, the surface pressure is locally reduced, and the progress of wear is slowed down.

  As shown in FIG. 5A, the initial wear period of Comparative Example 4 having the lowest surface hardness of the piston 109 is relatively short, and the initial wear period of Comparative Example 3 having the highest surface hardness tends to be relatively long. Indicates.

  In addition, in Fig.5 (a), as a conventional example, the HFC type | system | group refrigerant | coolant is used, and it has surface hardness of the same vane 110 and HRC40-60 (the range mainly used when using an HFC refrigerant | coolant). The upper limit value of the amount of piston wear after the compressor having the piston 109 is overloaded for 2000 hours is indicated by a dotted line.

  As shown to Fig.5 (a), all of Example 2, the comparative example 3, and the comparative example 4 are a wear amount substantially equivalent to a prior art example (when using a HFC refrigerant | coolant). The wear amount of the piston 109 of Comparative Example 4 having the lowest surface hardness is relatively large, and the wear amount of Example 2 and Comparative Example 3 having the highest surface hardness is substantially the same.

  Next, the characteristics of the refrigerating machine oil total acid value shown in FIG.

  In addition, in FIG.5 (b), the surface hardness of the same vane 110 and HRC40-60 (the range mainly used when using an HFC type refrigerant | coolant) is used as a prior art, and an HFC type refrigerant | coolant is shown. The upper limit value of the total acid value of the refrigerating machine oil after overloading the compressor having the piston 109 provided for 2000 hours is indicated by a dotted line.

  In all of Example 2, Comparative Example 3, and Comparative Example 4, the rate of increase in the total acid value is initially high, and the rate of increase in the total acid value tends to decrease with time.

  Comparative Example 3 with the highest surface hardness of the piston 109 has the largest increase in total acid value, and the total acid value of Comparative Example 3 is larger than the total acid value of the conventional example (when using an HFC refrigerant). High value. Moreover, the comparative example 4 with the lowest surface hardness of the piston 109 also finally has a higher value than the conventional example. On the other hand, the total acid value of Example 2 is finally at the same level as the conventional example.

  In the following, consideration will be given to the characteristic correlation between the operating time, the amount of wear of the piston 109, and the total acid number.

  The difference in the total acid value between Example 2 and Comparative Example 3 is considered to be due to the hardness of the piston 109. In general, the local temperature rise of the sliding part is caused by the contact of microprotrusions existing on the sliding surfaces that slide with each other, and the degree of the temperature rise is the radius of the contact point of the microprotrusions. It is said to be inversely proportional to If the surface hardness of the piston 109 is too high with respect to the vane 110 coated with CrN ceramic, the surface of the piston 109 and the surface of the vane 110 are difficult to conform to each other, that is, the minute protrusions of the piston 109 are difficult to disappear. The radius of the contact point of the microprojection existing on the surface of the piston 109 is kept small. Therefore, the region between the vane 110 and the piston 109 is maintained in a locally high temperature state. Further, referring to FIGS. 5A and 5B, the initial wear period (that is, the period until the microprojections disappear) and the period during which the increase rate of the total acid number is high are substantially the same. In other words, the period during which the region between the vane 110 and the piston 109 is maintained in a locally high temperature state substantially coincides with the period during which the increase rate of the total acid number is high. From this, during the initial wear period, decomposition of the HFO1234yf refrigerant having a carbon double bond, which is less stable than the conventionally used HFC refrigerant, occurred in the region between the vane 110 and the piston 109. It can be inferred that it was promoted by heat. The HFO1234yf refrigerant is decomposed to generate hydrogen fluoride (hydrofluoric acid), and the generated hydrogen fluoride contributes to the decomposition of the refrigerating machine oil 103 (generation of carboxylic acid and the like), thereby increasing the total acid value. It can be inferred that the change was reflected. Therefore, in order to suppress the increase in the total acid value, by making the difference in the surface hardness of the vane 110 and the piston 109 appropriate, in other words, by appropriately setting the upper limit value of the surface hardness of the piston 109. It is necessary to quickly end the initial wear, and thereby quickly shift to the steady wear in which the surface pressure is locally reduced.

  On the other hand, as shown in FIG. 5 (b), the total acid value of Comparative Example 4 with the lowest surface hardness of the piston 109 is similar to the total acid value of Comparative Example 3 with the highest hardness of the piston 109. The cause higher than the example can be inferred as follows.

  In the case of Comparative Example 4, the amount of piston wear is large. Since the exhausted powder discharged is very activated, it is considered that it becomes a catalyst and promotes the decomposition of the HFO1234yf refrigerant. Therefore, it can be inferred that the total acid value of Comparative Example 4 in which the most wear powder is generated is higher than that of the conventional example, that is, the case of using the HFC refrigerant. Therefore, it is necessary to ensure wear resistance by appropriately setting the difference in surface hardness between the vane 110 and the piston 109, in other words, the lower limit value of the surface hardness of the piston 109.

  FIG. 6 (a) and FIG. 6 (b) show the characteristic correlation between the piston wear amount and the total acid value of the refrigerating machine oil with respect to the piston surface hardness. The characteristic correlation shown in the figure was obtained by the following test. The vane 110 used for the test is made of high-speed tool steel (SKH51), and a CrN ceramic coating film having a surface hardness of about HV1800, a film thickness of 5 μm, and a surface roughness Ra of 0.2 μmRa is formed. The refrigerant used for the test is HFO1234yf refrigerant. The refrigerating machine oil 103 is a polyol ester. A plurality of rotary compressors 120 having pistons 109 having different surface hardness and having a surface roughness of Ra of about 0.2 μm and made of monichro cast iron were prepared. Each compressor was overloaded for 1000 hours. After the test, the wear amount of the piston 109 and the total acid value of the refrigerating machine oil 103 were measured for each rotary compressor 120.

  The horizontal axis indicates the hardness of the piston 109, the vertical axis in FIG. 6 (a) indicates the amount of piston wear, and the vertical axis in FIG. 6 (b) indicates the total acid value.

  As shown in FIG. 6, when HFO1234yf refrigerant is used and the surface hardness of the piston 109 is in the range of HRC 47 to 55, the piston wear amount and the total acid value at the same level as in the conventional example (when using HFC refrigerant). It can be seen that can be secured.

  From the above results, a refrigerant containing a hydrofluoroolefin having a carbon double bond is used, a polyol ester containing an acid scavenger and an antiwear agent is used as the refrigerating machine oil 103, and the vane 110 of the rotary compressor 120 is used. In addition to making the ceramic coating from an iron-based material and setting the surface hardness of the piston 109 to HRC 47 to 55, decomposition and polymerization of the refrigerant and the refrigerating machine oil 103 can be suppressed (that is, generation of sludge is suppressed). The wear resistance of the vane 110 and the piston 109 can be maintained. As a result, the reliability of the compressor 120 and the refrigeration cycle apparatus using the compressor 120 can be ensured.

  In addition, you may mix the hydrofluorocarbon (HFC32, HFC125) which does not have a double bond with the tetrafluoropropene (HFO1234yf) which is a refrigerant | coolant of this Embodiment. This mixed refrigerant behaves in substantially the same manner as a pseudo-azeotropic mixed refrigerant having a small temperature difference between boiling points, despite the non-azeotropic mixed refrigerant. As a result, the cooling performance and the cooling performance coefficient (COP) of the cooling cycle apparatus are improved. Although a single refrigerant of hydrofluoroolefin is used in the present embodiment, the same effect can be obtained even when a mixed refrigerant containing hydrofluoroolefin and hydrofluorocarbon is used.

  In the case of a mixed refrigerant, the GWP is preferably mixed so as to be 5 or more and 750 or less, desirably 5 or more and 350 or less. For example, in order to mix HFO1234yf and HFC32 to make GWP350 or less, HFO1234yf needs to be 56 wt% or more. Moreover, in order to mix HFO1234yf and HFC125 to make GWP750 or less, HFO1234yf needs to be 78.7 wt% or more, and in order to make GWP350 or less, HFO1234yf needs to be 91.6 wt% or more. Thereby, the influence with respect to global warming of a refrigerant | coolant can be kept to the minimum.

  Moreover, although the polyol ester oil compatible with HFO1234yf was used as the refrigerating machine oil 103, polyvinyl ether or polyalkylene glycol which is also compatible may be used as the refrigerating machine oil 103. Even if these refrigerating machine oils are used, the compressor 120 can recover these refrigerating machine oils, so that a highly reliable compressor 120 can be obtained in the same manner as the polyol ester oil. In addition, since these refrigerating machine oils are also compatible with the mixed refrigerant of HFO1234yf and HFC, the same effects as the polyol ester oil can be obtained.

  Furthermore, the piston 109 of the present embodiment has a chromium (Cr) content of 0.7-1.0 wt%, a molybdenum (Mo) content of 0.2-0.4 wt%, and a nickel (Ni) content of 0.2-0. It is made from monichro cast iron containing 4 wt%. However, a similar effect can be obtained with a piston 109 made of monichrome cast iron containing 0.4 to 1.2 wt% chromium, 0.15 to 0.7 wt% molybdenum, and 0.15 to 0.4 wt% nickel. can get. Further, the same effect can be obtained even when a piston 109 made of cast iron not containing nickel (mocro cast iron) is used.

  Furthermore, cast iron is used as a material for producing the piston 109 of the present embodiment, but other iron-based materials containing chrome, molybdenum, nickel (for example, carbon steel, tool steel, etc.) are used. May be used.

  In addition, the surface roughness (surface roughness of the ceramic coating film) of the tip 110a of the vane 110 of this embodiment and the surface roughness of the piston 109 (flat portion excluding minute recesses) are about Ra 0.2 μm. However, if Ra is 0.4 μm or less, the same effect can be obtained. When Ra is 0.4 μm or more, the tip 110a of the vane 110 and the outer peripheral surface of the piston 109 become difficult to conform, and as a result, there is a possibility that the total acid value increases.

  In addition, although this invention was demonstrated taking the example of the vane 110 and the piston 109, this invention is applicable also to the other sliding part of the compressor 120, for example, the sliding part of a shaft and a bearing. Further, the present invention is not limited to a rotary type compressor, and can be applied to a compressor such as a scroll compressor. A scroll compressor has a fixed side, a turning side scroll, etc. as a sliding part.

  While the invention has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as being included therein, so long as they do not depart from the scope of the present invention according to the appended claims.

  Japanese Patent Application No. 2010-199604 filed on Sep. 7, 2010 and Japanese Patent Application No. 2010-234329 filed on Oct. 19, 2010, drawings, and claims. The disclosure is hereby incorporated by reference in its entirety.

  As described above, the compressor according to the present invention and the refrigeration cycle apparatus using the compressor use a mixed refrigerant of a hydrofluoroolefin having a carbon double bond and a hydrofluorocarbon having no carbon double bond. The reliability of the compressor can be ensured. Therefore, the present invention can also be applied to a compressor for a water heater, a compressor for a car air conditioner, a compressor for a refrigerator-freezer, a compressor for a dehumidifier, and the like.

DESCRIPTION OF SYMBOLS 103 Refrigerating machine oil 105 Compression mechanism part 106 Cylinder 109 Piston 110 Vane 120 Compressor 121 Condenser 122 Expansion mechanism 123 Evaporator

Claims (15)

A compressor used in a refrigeration cycle apparatus,
A single refrigerant of a hydrofluoroolefin having a carbon double bond or a mixed refrigerant comprising the hydrofluoroolefin and a hydrofluorocarbon having no carbon double bond is used;
The refrigerating machine oil containing an additive for suppressing deterioration of the refrigerating machine oil and an antiwear agent is used,
As a sliding portion exposed to the mixed refrigerant and the refrigerating machine oil, having a piston and a vane that slide with each other,
The vanes are ceramic coated and have a hardness of HV 1500-2000,
The compressor, wherein the piston has a hardness of HRC 47-55. The compressor of claim 1 , wherein the vane is made from high speed tool steel. The surface of the vane according to claim 1 or 2 , wherein a nitride or carbide of Ti (titanium), V (vanadium), Ta (tantalum), W (tungsten), or Nb (niobium) is coated on the surface of the vane. The compressor described. The compressor according to any one of claims 1 to 3 , wherein the ceramic coating thickness of a tip portion of the vane contacting the piston is 5 to 15 µm. The compressor according to any one of claims 1 to 4 , wherein the ceramic coating is performed only on a tip portion of the vane. The compressor according to any one of claims 1 to 5 , wherein the piston is made of cast iron. The compressor according to claim 6 , wherein the cast iron contains 0.4 to 1.2 wt% chromium and 0.15 to 0.7 wt% molybdenum. The compressor according to claim 6 or 7 , wherein the cast iron contains 0.15 to 0.4 wt% of nickel. The compressor according to any one of claims 1 to 8 , wherein a surface of the vane and a surface of the piston have a surface roughness of Ra 0.4 µm or less. The refrigerant is a type of hydro fluoroolefin comprises at least one tetrafluoropropene or trifluoropropene, global warming is 5 or more 750 or less, according to any one of claims 1-9 Compressor. The compressor according to claim 10 whose global warming potential of said refrigerant is 5 or more and 350 or less. The refrigerant is mainly composed of tetrafluoropropene or trifluoropropene, which is a kind of hydrofluoroolefin,
The compressor according to any one of claims 1 to 9 , wherein difluoromethane and pentafluoroethane are mixed in the refrigerant so that a global warming potential is 5 or more and 750 or less. The compressor according to claim 12 , wherein difluoromethane and pentafluoroethane are mixed with the refrigerant so that a global warming potential is 5 or more and 350 or less. The refrigerating machine oil comprises (1) polyoxyalkylene glycols, (2) polyvinyl ethers, (3) poly (oxy) alkylene glycol or a copolymer of its monoether and polyvinyl ether, (4) polyol esters and polycarbonate. synthetic oil containing oxygen-containing compounds like, (5) synthetic oil as a main component alkylbenzenes, or (6) is a synthetic oil composed mainly of α-olefins, any one of claims 1 to 13 The compressor described in 1. The compressor according to any one of claims 1 to 14 ,
A condenser,
An expansion mechanism;
With an evaporator,
A refrigeration cycle apparatus that forms a refrigeration cycle that compresses, condenses, expands, and evaporates refrigerant.

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