JP2015017730A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner suppressing hydrolysis of an insulation film in a motor of a compressor.SOLUTION: An air conditioner includes: a compressor; an outdoor heat exchanger; an expansion mechanism; an indoor heat exchanger; coolant comprising R32 or mixed coolant containing R32 of more than 50 wt.%; polyol ester oil having aliphatic acid having 5 or less carbon atoms within a range where the number of ester groups is 4 or more, a saturated moisture content is 1000 ppm or more, and a kinetic viscosity is 40-100 mm/s. The compressor includes a motor, and an insulation film of the motor comprises polyethylene terephthalate or polyethylene naphthalate.

Description

  The present invention relates to an air conditioner.

  In the air conditioner, R410A is used as a refrigerant. However, in order to reduce the influence on the global environment, it is considered to shift to difluoromethane (hereinafter referred to as “R32”) whose global warming potential (hereinafter referred to as “GWP”) is about 1/3 of R410A. Has been.

  By the way, the motor insulation film built in the compressor is required to be easily processed. Currently, polyethylene terephthalate (hereinafter referred to as “PET”) and polyethylene naphthalate (hereinafter referred to as “PEN”), which are easy to process, are used for the insulating film.

  However, since PET and PEN are hydrolyzable, there is a possibility that the PET and PEN may be hydrolyzed by moisture in the refrigeration cycle.

  Although the insulation of the motor can be maintained by using polyphenylene sulfide or polyetheretherketone as an insulating film as a material that does not cause hydrolysis, problems such as increased cost and reduced productivity due to hardness arise.

  On the other hand, Patent Document 1 discloses that moisture in the refrigeration cycle is absorbed by using polyvinyl ether having hygroscopicity for the refrigerating machine oil to suppress hydrolysis of the insulating film.

Patent No. 4836305

  However, polyvinyl ether oil does not cause a chemical reaction to absorb water, but merely retains moisture. Therefore, polyvinyl ether oil has a characteristic of releasing retained moisture when heated.

  The insulating film is built in the compressor, and when the operation is started, the inside of the compressor becomes hot. In particular, when R32 is used as the refrigerant, the interior of the compressor is likely to be hotter than R410A. That is, the polyvinyl ether oil containing moisture may release moisture inside the compressor, and the insulating film may be hydrolyzed.

  The objective of this invention is providing the air conditioner which suppressed the hydrolysis of the insulating film of the motor incorporated in the compressor.

The air conditioner of the present invention includes a compressor, an outdoor heat exchanger, an expansion mechanism, an indoor heat exchanger, a refrigerant composed of R32 or a mixed refrigerant containing more than 50% by weight of R32, an ester, number four or more, the saturated water content of 1000ppm or higher, and a kinematic viscosity in a range of 40mm ² / s~100mm ² / s, with a polyol ester oil carbon atoms having five or less fatty acid, The compressor has a built-in motor, and the insulating film of the motor is made of polyethylene terephthalate or polyethylene naphthalate.

  ADVANTAGE OF THE INVENTION According to this invention, the air conditioner which suppressed the hydrolysis of the insulating film of the motor of a compressor can be provided.

It is the schematic of the air conditioner combined with air conditioning. It is the schematic of a hermetic compressor.

  Hereinafter, an air conditioner according to an embodiment of the present invention will be described.

  FIG. 1 is a schematic view of an air conditioner that is also used for air conditioning. The air conditioner of this embodiment connects the compressor 1, the outdoor heat exchanger 3, the expansion mechanism 4, and the indoor heat exchanger 5 with piping, and a refrigerant circulates.

  In the case of the cooling operation, the high-temperature and high-pressure gas refrigerant compressed by the compressor 1 flows to the outdoor heat exchanger 3 via the four-way valve 2. The high-temperature and high-pressure gas refrigerant is cooled by the outdoor heat exchanger 3 functioning as a condenser, and becomes a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is expanded by the expansion mechanism 4 and becomes a low-temperature and low-pressure liquid refrigerant containing a slight amount of gas and flows to the indoor heat exchanger 6. The low-temperature and low-pressure liquid refrigerant is heated by the indoor heat exchanger 6 functioning as an evaporator, becomes a low-temperature gas refrigerant, and returns to the compressor 1 through the four-way valve 2 again. In the heating operation, the refrigerant flow is changed by the four-way valve 2, and the refrigerant flows in the opposite direction to the cooling operation.

  In addition, you may comprise so that it may have only the function of either cooling or heating, without using the four-way valve 2. As the expansion mechanism 4, an electronic expansion valve, a capillary tube, a temperature type expansion mechanism, or the like can be used.

  FIG. 2 is a schematic view of the compressor. The compressor 1 engages the fixed scroll member 8 having the end plate 9 and the spiral wrap 10 and the orbiting scroll member 11 having the wrap 12 with the wrap 10 and the wrap 12 facing each other to engage the compression mechanism portion. Then, the orbiting scroll member 11 is orbited by the crankshaft 13. Of the compression chambers 14 (14a, 14b...) Formed by the fixed scroll member 8 and the orbiting scroll member 11, the outermost compression chamber is gradually reduced in volume with the orbiting motion. The fixed scroll member 8 and the orbiting scroll member 11 move toward the center. When the compression chamber 14 reaches the vicinity of the center of the fixed scroll member 8 and the orbiting scroll member 11, the compression chamber 14 communicates with the discharge port 15, and the gas refrigerant compressed in the compression chamber 14 passes through the discharge pipe 18. It is discharged outside.

  The compressor 1 has a built-in electric motor 19 in the pressure vessel 17, and the compressor 1 rotates at a constant speed or at a rotational speed corresponding to a voltage controlled by an inverter (not shown) to perform a compression operation. Do. The electric motor 19 operates in an atmosphere of refrigerant and refrigeration oil. An insulating film is arranged between the phases of coils (not shown) of the motor 19 and between the laminated steel plates in order to maintain insulation. Further, an oil sump is provided at the lower portion of the electric motor 19, and the refrigerating machine oil accumulated in the oil sump passes through the oil hole 21 provided in the crankshaft 13 due to a pressure difference, and the orbiting scroll member 11 and the crank. It is used for lubrication of the sliding portion with the shaft 13, the sliding bearing 20, and the like.

  As the insulating film, PET or PEN, which is easy to process, is used. However, since PET and PEN are hydrolyzable, it is necessary to remove the water present in the refrigeration cycle in some form. Therefore, in the present embodiment, as a means for removing moisture present in the refrigeration cycle, a polyol ester oil having hygroscopicity and reactivity with moisture is used as the refrigerating machine oil.

Table 3 shows the results of experiments on the suppression of hydrolysis of the insulating film by polyol ester oil. Example 1 uses a polyol ester oil that is compatible with R32 represented by the following chemical formulas (1) and (2), and the comparative example uses a refrigerating machine oil that is hygroscopic but not reactive with moisture. It was. Specifically, Comparative Example 1 is a side chain represented by the following chemical formula (3) (wherein m = 90 and n = 10, and R ² and R ³ represent a methyloxy group and an ethyloxy group). The ether oil, Comparative Example 2, used a cyclic ether oil represented by the following chemical formula (4) (wherein R ⁴ and R ⁵ represent hydrogen or an alkyl group having 1 to 3 carbon atoms).

  When installing a room air conditioner, if the indoor unit and the outdoor unit are connected by a connecting pipe without evacuation, the maximum amount of water is 1000 ppm in the refrigeration cycle, although it depends on the humidity of the outside air and the length of the connecting pipe. It is thought that it mixes. Therefore, the moisture content mixed into the compressor 1 is assumed to be 1,000 ppm, and the moisture content in the oil is set to 1,000 ppm.

  Moreover, when R32 is employ | adopted as a refrigerant | coolant, the discharge temperature of the compressor 1 may rise to 140 degreeC. Then, the reliability test of the insulating film in case R32 is employ | adopted as a refrigerant | coolant was done. Table 1 shows the viscosity of refrigerating machine oil, the critical solution temperature with R32, and the tensile strength and elongation of the insulating film after dipping the insulating film in a mixed solution of R32 alone and refrigerating machine oil at 140 ° C. for 40 days. It is the result of measurement.

  In Example 1, as shown in Table 1, the viscosity of the refrigerating machine oil and the critical melting temperature with R32 were not changed, and the breaking strength and elongation of the insulating film were maintained at 80% or more with respect to the initial values.

  On the other hand, in Comparative Example 1, as shown in Table 1, the viscosity of the refrigerating machine oil and the critical solution temperature with R32 did not change, but the elongation of the insulating film was 70% or less with respect to the initial value. . Although the insulating film depends on the place where it is used, it is often used mainly by being bent or wound into a tube shape, and therefore, how much the insulating film extends beyond the tensile strength, that is, the elongation is important. If the elongation is less than 70% of the previous history, there is a possibility that the folded portion of the film is cracked during use or the film may be broken. Therefore, Comparative Example 1 cannot suppress deterioration of the insulating film. It can be said.

  In Comparative Example 2, as shown in Table 1, a component that was considered to be a deteriorated insulating film was precipitated, and the turbidity of the refrigerating machine oil was observed. Since the degradation product of the insulating film is not dissolved in the oil, there is a possibility that the capillary tube or the like is blocked. When cooled, the components aggregated, becoming more cloudy and the critical solution temperature could not be measured. The elongation of the insulating film was also 70% or less, and it was impossible to suppress the deterioration of the insulating film.

  From the above results, it can be seen that it is effective to use a polyol ester oil having hygroscopicity and reactivity with moisture as a refrigerating machine oil in order to suppress degradation due to hydrolysis of the insulating film.

  In addition, the refrigerating machine oil of the present embodiment is preferably a highly hygroscopic oil among polyol ester oils in order to absorb moisture in the refrigeration cycle. Since the air conditioner may contain about 1,000 ppm of moisture as described above, the saturated moisture content of the refrigerating machine oil needs to be 1,000 ppm or more.

  Table 2 shows the results obtained by injecting water into the polyol ester oil so that the water content becomes 1,000 ppm, shaking and observing. Refrigerator oil component A uses neopentyl glycol (number of ester groups: 2) as a polyhydric alcohol, Refrigerator oil component B uses trimethylolpropane (number of ester groups: 3) as a polyhydric alcohol, The refrigerating machine oil component C uses pentaerythritol (number of ester groups: 4) as the polyhydric alcohol, and the refrigerating machine oil component D is the same as that in Example 1 in Table 1, and the polyhydric alcohols are pentaerythritol and dipentayl. Those using erythritol (number of ester groups: 6) were used.

  As shown in Table 2, it was observed that the refrigerating machine oil component A and the refrigerating machine oil component B having a small number of ester groups in the structure were separated in water and precipitated in the oil.

  On the other hand, with regard to the refrigerating machine oil component C and the refrigerating machine oil component D, the water did not separate even after 60 minutes or longer. That is, it was found that the polyol ester oil has a saturated water content of 1,000 ppm or more when the number of ester groups is 4 or more.

  The refrigerating machine oil to be compatible varies depending on the type of refrigerant. If a refrigerating machine oil that is incompatible with R32 is used, it is difficult for the refrigerating machine oil to be supplied to the sliding part at the start-up in winter, and the refrigerating machine oil discharged outside the compressor 1 enters the low temperature part of the refrigerating cycle. The oil return property deteriorates by staying.

  Then, compatibility evaluation with refrigeration oil and R32 was performed. Table 3 shows the refrigerating machine oil used for the compatibility evaluation with R32, and Table 4 shows the refrigerating machine oil compatibility evaluation shown in Table 3. The refrigerating machine oil components C1 to C5 are pentaerythritol having up to four esters. The refrigerating machine oil component D is pentaerythritol and dipentaerythritol having a maximum of 6 esters. The refrigerating machine oil component B1 is trimethylolpropane having a maximum of three esters. The refrigerating machine oil component A1 is neopentyl glycol having a maximum of two esters.

  As shown in Comparative Example 6, the low-temperature critical dissolution temperature of the refrigerator oil components C2 and R410A is 10 ° C. or lower. However, as shown in Comparative Example 1, the low temperature side critical dissolution temperature of the same refrigerating machine oil components C2 and R32 as in Comparative Example 8 is 20 ° C. or higher, and the refrigerating machine oil component C2 that has been used in an air conditioner using R410A. Resulted in poor compatibility with R32.

  Further, as shown in Comparative Examples 2 and 3, the compatibility was not improved even with the refrigerating machine oil component C3 and the refrigerating machine oil component C4 in which the viscosity was changed with respect to the refrigerating machine oil component C2.

  On the other hand, as shown in Comparative Examples 6 and 7, the critical solution temperature of the refrigerating machine oil component B1 and the refrigerating machine oil components A1 and R32 using fatty acids having a relatively small number of carbon atoms was -10 degrees or less. That is, it was found that the polyol ester oil is improved in compatibility with R32 by using a fatty acid having a relatively small number of carbons as a raw material.

Incidentally, the viscosity of the refrigerating machine oil used in the air conditioner of the present embodiment varies depending on the kind of the compressor 1, the viscosity at 40 ° C. in the case of a scroll compressor or a rotary compressor 40mm ² / s~100mm ² / s The range of is preferable. When the viscosity is less than 40 mm ² / s, the viscosity of the refrigerating machine oil in which the refrigerant is dissolved becomes low, and the oil film inside the compressor 1 is not sufficiently maintained, and the lubricity cannot be maintained. On the other hand, when the viscosity exceeds 100 mm ² / s, opportunity loss such as viscosity resistance and frictional resistance increases, which may reduce the compressor efficiency.

As shown in Comparative Examples 6 and 7, the refrigerating machine oil component B1 and the refrigerating machine oil component A1 are excellent in compatibility with R32, but the viscosity is 30 mm ² / s or less because the average number of ester groups in the composition is small. Therefore, it cannot be employed as a refrigerating machine oil for an air conditioner.

On the other hand, the refrigerating machine oil component D1 and the refrigerating machine oil component C1 shown in the first and second embodiments using the fatty acid having a relatively small number of carbon atoms and the alcohol having an average number of ester groups of 4 or more are low in temperature with R32. side critical solution temperature is at 10 ° C. or less, a kinematic viscosity in the range of 40mm ² / s~100mm ² / s, it can be applied to the refrigeration air conditioning system.

As explained above, the refrigerating machine oil in this embodiment, esters its number 4 or more, the saturated water content of 1000ppm or higher, and a kinematic viscosity in a range of 40mm ² / s~100mm ² / s A polyol ester oil having a fatty acid having 5 or less carbon atoms.

Saturated water content 1,000ppm or more, 10 ° C. low temperature side critical solution temperature with R32 or less, for kinematic viscosity to produce satisfying refrigerating machine oil in the range of 40mm ² / s~100mm ² / s, as a raw material Examples of the polyhydric alcohol include pentaerythritol and dipentaerythritol. Examples of the monovalent fatty acid include fatty acids having 4 to 5 carbon atoms and relatively few carbon atoms such as butanoic acid, pentanoic acid, 2-methylpropanoic acid, and 2-methylbutanoic acid. In order to prevent abnormal viscosity reduction of the base oil, octanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, 3,5,5-trimethylhexanoic acid, etc. A fatty acid having a relatively large number of carbon atoms having 8 to 12 carbon atoms may be mixed.

Furthermore, the ester oil of the fatty acid represented by the chemical formula (1) or (2) having at least 4 ester groups in the molecule (wherein R ¹ is an alkyl group having 4 to 5 carbon atoms or 8 to 12 carbon atoms). It is an alkyl group, and at least one of R ^{1 in} the formula is preferably one or a mixture of two selected from the group of 4 to 5 carbon atoms.

  In the present embodiment, there is no problem even if a lubricity improver, an antioxidant, an acid scavenger, an antifoaming agent, a metal deactivator, and the like are added to the above-described refrigerating machine oil. In particular, the polyol ester oil is deteriorated due to hydrolysis in the presence of moisture, and therefore it is essential to add an antioxidant and an acid scavenger. As the antioxidant, phenol-based 2,6-di-t-butyl-p-cresol (DBPC) is preferable.

  Moreover, the effect can be further improved by blending an additive having a moisture trapping effect in the refrigerating machine oil.

  As an example of the additive to be blended, alkyl glycidyl ester can be mentioned. Since this additive has an effect of capturing not only the acid produced by the degradation of the polyol ester oil but also the water itself, the ability to absorb the water as the refrigerating machine oil is improved.

  In the form of this embodiment, the motor insulation film provided in the compressor is made of PET or PEN, but it may be a composite material such as other polymer resin having an ester bond or a laminated film using a resin having an ester bond. Good.

  The air conditioner according to the present invention can be applied to a separate type in which a condenser and an evaporator are separated and connected by a refrigerant pipe, or a multi-type having a plurality of condensers or evaporators. is there.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  In this embodiment, the case where R32 is used as the refrigerant has been described. However, the present invention can also be applied to a mixed refrigerant containing more than 50% by weight of R32.

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four-way valve, 3 ... Outdoor heat exchanger, 4 ... Expansion means, 5 ... Indoor heat exchanger

Claims (2)

A compressor, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger;
R32 or a refrigerant made of a mixed refrigerant containing more than 50% by weight of R32;
Esters its number 4 or more, the saturated water content of 1000ppm or higher, and a kinematic viscosity in a range of 40mm ² / s~100mm ² / s, a polyol ester oil carbon atoms having five or fewer fatty acids With
The compressor includes a motor, and the motor insulating film is made of polyethylene terephthalate or polyethylene naphthalate. The polyol ester oil is an ester oil of a fatty acid represented by the chemical formula (1) or (2) (wherein R ¹ is an alkyl group having 4 to 5 carbon atoms or an alkyl group having 8 to 12 carbon atoms, 2. The air conditioner according to claim ¹ , wherein at least one of R ¹ is an alkyl group having 4 to 5 carbon atoms).