JP2009138037A - Refrigerant compressor and heat pump water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerant compressor which can satisfactorily keep an electrical insulation property, has proper compatibility between carbon dioxide as refrigerant and refrigerator oil, can suppress foaming of carbon dioxide in the refrigerator oil and is excellent in wear resistance in a sliding part. <P>SOLUTION: The refrigerant compressor comprises a motor and a refrigerant compressor part which is connected with the motor via a rotation shaft and compresses refrigerant, wherein the refrigerant is carbon dioxide and at least one kind of polyol ester represented by the following formulas (1) and (2) containing an antifoaming agent is used as the refrigerator oil; C-(CH<SB>2</SB>OCOR)<SB>4</SB>(1), (R-COOCH<SB>2</SB>)<SB>3</SB>-C-O-C-(CH<SB>2</SB>OCO-R)<SB>3</SB>(2). In formulas (1), (2), R denotes an alkyl group of 11 to 19 C independently. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a refrigerant compressor using carbon dioxide as a refrigerant and using a polyol ester as a refrigerating machine oil, and a heat pump hot water heater equipped with the refrigerant compressor.

  In recent years, the refrigerant of the refrigeration cycle has shifted from a hydrofluorocarbon (hereinafter sometimes referred to as HFC) to a natural refrigerant from the viewpoint of global environmental conservation. In particular, carbon dioxide is nonflammable and has low toxicity, and can achieve energy saving and high efficiency of equipment applied to the refrigeration cycle. Examples of such applied equipment include electric car air conditioners, cold district heating equipment, and hot water heaters. Among them, the heat pump type hot water heater using carbon dioxide has a running cost as low as about one-fifth compared with a gas type hot water heater generally used as a home water heater. In addition, in comparison with an electric water heater, a heat pump type water heater using carbon dioxide has a coefficient of performance (COP) of 3.0 or more, so that the efficiency of the water heater can be increased. In addition, the heat pump type hot water heater using HFC as the refrigerant stops the hot water temperature at about 60 ° C. due to the physical properties of the refrigerant. Therefore, in order to supply hot water at a higher temperature, an extremely high output refrigerant compressor Is required. On the other hand, the heat pump type hot water heater using carbon dioxide can make the hot water temperature about 90 ° C. without using a high-output refrigerant compressor.

  On the other hand, refrigeration oil is used for the hermetic refrigerant compressor. This refrigerating machine oil plays a role of lubrication, sealing, cooling, etc. in the sliding part of the refrigerant compressor. By the way, in the above-described refrigerant compressor using carbon dioxide, refrigeration oil is used at a high temperature of 120 to 130 ° C. and a high pressure of about 15 MPa. Therefore, the refrigerating machine oil used in the refrigerant compressor is required to have lubricity in order to ensure the reliability of the refrigerant compressor, and the refrigerating cycle application equipment in which the refrigerant compressor is used. What can achieve energy saving and high efficiency is required.

Conventionally, as a refrigerating machine oil of a refrigerant compressor using carbon dioxide, polyalkylene glycol having both ends alkylated is known (for example, see Patent Document 1). This refrigerating machine oil is excellent in compatibility with carbon dioxide and in thermochemical stability.
However, polyalkylene glycol has a volume resistivity significantly lower than 10 ¹³ Ω · cm, which is the standard of the Electrical Appliance and Material Safety Law, and has a very high dielectric constant of 5.0 F · m ^−1. It is difficult to make the value below the reference value (1.0 mA) defined in the Electrical Appliance and Material Safety Law. In particular, in large capacity refrigerant compressors used in instantaneous water heaters, the volume resistivity of the refrigerating machine oil used tends to increase at high speed from the start of hot water supply and the leakage current value tends to increase. Is desired to be as low as possible. Moreover, since polyalkylene glycol may also hydrolyze the ester-type insulating film used for the motor part of a refrigerant compressor, there also exists a possibility of inhibiting the electrical insulation of a motor part.
Further, as a refrigerating machine oil having a high volume resistivity as compared with this polyalkylene glycol, polyol ester (for example, see Patent Document 2) or hydrocarbon oil (for example, Patent Document 3, Patent Document 4, Patent Document 5). See).
Japanese Patent Laid-Open No. 10-46169 JP 2000-104084 A JP 2001-294886 A JP 2000-110725 A JP 2003-336916 A

  However, since polyol ester (for example, refer patent document 2) is too rich in the compatibility with the carbon dioxide as a refrigerant | coolant, a viscosity will fall significantly in the refrigerant | coolant compressor in operation. As a result, the sealing performance in the refrigerant compressor portion of the refrigerant compressor becomes insufficient, and the operation efficiency is lowered. In particular, since the refrigeration cycle using carbon dioxide as a refrigerant operates in a supercritical state, the amount of polyol ester sent out together with the refrigerant from the refrigerant compressor side is reduced because the compatibility between carbon dioxide and the polyol ester is too rich. Increase in pressure may cause pressure loss. And since the amount of polyol ester in the carbon dioxide sent out from the refrigerant compressor side increases, the heat exchange efficiency may be significantly reduced. Further, carbon dioxide dissolved in the polyol ester is foamed in a reduced pressure state, so that an oil film is not sufficiently formed at the sliding portion of the refrigerant compressor. As a result, the wear resistance at the sliding portion of the refrigerant compressor is deteriorated. In addition, the refrigeration cycle may cause a reduction in compression efficiency due to the foaming of carbon dioxide in a reduced pressure state.

  Also, hydrocarbon oils (see, for example, Patent Document 3, Patent Document 4, and Patent Document 5) are so-called oils because they are poorly compatible with carbon dioxide as a refrigerant and stay in the low temperature part of the refrigeration cycle. Returnability is bad. As a result, the amount of refrigerating machine oil in the refrigerant compressor is reduced, and the wear resistance at the sliding portion may be deteriorated.

  Therefore, the present invention can maintain the electrical insulation well, and the compatibility between the refrigerant carbon dioxide and the refrigerating machine oil is moderate, and the carbon dioxide is prevented from foaming in the refrigerating machine oil. It is an object of the present invention to provide a refrigerant compressor that is excellent in wear resistance at a sliding portion and a heat pump type water heater equipped with the refrigerant compressor.

The present invention for solving the above-mentioned problems is directed to a refrigerant compressor in which a motor and a compressor unit that is coupled to the motor via a rotating shaft and compresses the refrigerant are housed in a sealed container that stores refrigerating machine oil. Is carbon dioxide, and the refrigerating machine oil is at least one polyol ester represented by the following formula (1) and formula (2) containing an antifoaming agent.
C- (CH ₂ OCOR) ₄ (1)
(R—COOCH ₂ ) ₃ —C—O—C— (CH ₂ OCO—R) ₃ (2)
(However, in said Formula (1) and said Formula (2), R represents a C11-C19 alkyl group independently)
Moreover, the heat pump type water heater of the present invention that solves the above-described problems is characterized by including the above-described refrigerant compressor.

  According to the present invention, electrical insulation can be satisfactorily maintained, compatibility between carbon dioxide as a refrigerant and refrigerating machine oil is moderate, and suppression of foaming of carbon dioxide in refrigerating machine oil is suppressed. Therefore, it is possible to provide a refrigerant compressor that is excellent in wear resistance at the sliding portion, and a heat pump type water heater equipped with the refrigerant compressor.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. The main feature of the refrigerant compressor and the heat pump water heater equipped with the refrigerant compressor according to the present embodiment is that carbon dioxide is used as a refrigerant, and a predetermined polyol ester containing an antifoaming agent described later is used as a refrigerating machine oil. Here, after describing the instantaneous water heater on which the refrigerant compressor according to the present embodiment is mounted, the refrigerant compressor will be described. In the drawings referred to here, FIG. 1 is a configuration explanatory view of a heat pump type hot water heater equipped with a refrigerant compressor according to an embodiment. FIG. 2 is a conceptual diagram showing the arrangement of the refrigerant compressor, the water refrigerant heat exchanger, the air side heat exchanger, the hot water storage tank, and the blower fan in the heat pump type hot water heater of FIG. 1 as viewed from the blow fan side. It is a side view. FIG. 3 is a cross-sectional view of the refrigerant compressor.

As shown in FIG. 1, in the heat pump type hot water heater S according to the present embodiment, two refrigerant compressors 1A using carbon dioxide as a refrigerant and a refrigerant compressor 1B are operated in parallel to form two heat pump cycles. It is what is done.
In this heat pump type hot water heater S, the refrigerant compressors 1A and 1B compress low-temperature and low-pressure refrigerant gas (carbon dioxide), discharge high-temperature and high-pressure refrigerant gas, and send the refrigerant gas to the water refrigerant heat exchanger 2. The refrigerant gas sent to the water-refrigerant heat exchanger 2 performs sensible heat exchange with the low-temperature water supplied with the heat. After that, the electric expansion valves 3A and 3B are passed through, and the pressure becomes low at low temperature and sent to the air-side heat exchangers 4A and 4B. The refrigerant that has entered the air-side heat exchangers 4A and 4B absorbs heat from the surroundings and evaporates, and cool air is released by the blower fans 5A and 5B. The low-temperature and low-pressure refrigerant gas exiting the air side heat exchangers 4A and 4B is again sucked into the refrigerant compressors 1A and 1B, and the same cycle is repeated thereafter.
Thus, in the heat pump type hot water heater S using carbon dioxide as the refrigerant, the high pressure side exceeds the critical point because the heat pump cycle is operated in a supercritical state. Therefore, in this heat pump type hot water heater S, the high temperature side pressure can be set without any particular restriction, and high temperature water close to 100 ° C. can be easily obtained.

Next, the cycle which heats the water shown with the broken line in FIG. 1 is demonstrated. The low-temperature water 6 supplied from a predetermined water supply port is sent to the water-refrigerant heat exchanger 2 through the valve V1, and by sensible heat exchange with the refrigerant gas sent from the refrigerant compressors 1A, 1B. It becomes hot water 8. Since this heat pump type hot water heater S is an instantaneous type, hot water can be supplied from a predetermined outlet through the valves V2 and V3. At this time, the water 6 from the water supply port can be mixed with the hot water 8 in order to adjust the temperature of the hot water 8 sent from the water refrigerant heat exchanger 2.
Moreover, the hot water 8 from the water-refrigerant heat exchanger 2 can be once stored in the hot water storage tank 7 through the valve V2 and used. In addition, the heat pump type hot water heater S can be configured to be reheated by supplying the hot water 8 in the hot water storage tank 7 to the water refrigerant heat exchanger 2 again. Moreover, although not shown in figure, this heat pump type hot water heater S can be used also as a heat source of the total energy system for households, such as reheating of a bath tub, floor heating, and bathroom heating.

  Further, since the heat pump type hot water heater S is an instantaneous type, the hot water storage tank 7 can be reduced to an auxiliary size. Therefore, as shown in FIG. 2, the heat pump type hot water heater S moves the air side heat exchanger 4A and the air blowing fan 5A, and the air side heat exchanger 4B and the air blowing fan 5B up and down. The refrigerant compressors 1A and 1B are disposed below the air heat exchanger 4B and the blower fan 5B, and the hot water storage tank 7 around which the water refrigerant heat exchanger 2 is wound is provided as described above. Can be placed on the side. In other words, the heat pump type hot water heater S includes a heat source unit composed of the air side heat exchangers 4A and 4B, the blower fans 5A and 5B, and the refrigerant compressors 1A and 1B, the water refrigerant heat exchanger 2 and the hot water storage tank 7. It can be integrated with the hot water storage tank unit. As a result, according to this heat pump type hot water heater S, the equipment can be made compact.

Next, the refrigerant compressors 1A and 1B according to the present embodiment will be described. In addition, since the refrigerant compressor 1A and the refrigerant compressor 1B have the same structure, in the following description, only the refrigerant compressor 1A will be described, and the description of the refrigerant compressor 1B will be omitted.
As shown in FIG. 3, the refrigerant compressor 1 </ b> A includes a compressor unit C having a fixed scroll 9 and a turning scroll 14. The fixed scroll 9 includes an end plate 10 and a spiral wrap 11 formed so as to stand upright on the end plate 10, and the orbiting scroll 14 includes an end plate 12 and a spiral standing upright on the end plate 12. And a wrap 13. The end plate 10 and the end plate 12, and the spiral wrap 11 and the spiral wrap 13 have substantially the same shape, and the spiral wrap 11 and the spiral wrap 13 are meshed with each other. Thus, a compression chamber 16 is formed between the fixed scroll 9 and the orbiting scroll 14. The orbiting scroll 14 is adapted to orbit around the crankshaft 15. The crankshaft 15 corresponds to a “rotary shaft” in the claims.

  When such a turning scroll 14 is turned by the crankshaft 15, the compression chamber 16 formed by meshing the spiral wrap 11 and the spiral wrap 13 compresses and compresses the refrigerant gas taken in from the suction pipe 18a. The refrigerant gas is sent out to the discharge chamber 19a through the discharge port 17. The refrigerant gas is discharged from the discharge pipe 18b through the motor chamber 19b communicating with the discharge chamber 19a. Incidentally, the refrigerating machine oil 21 described later, which is moderately compatible with carbon dioxide, is sent to the water refrigerant heat exchanger 2 (see FIG. 1) side through the discharge pipe 18b together with carbon dioxide. And the sent out refrigerating machine oil 21 will be returned from the air side heat exchanger 4A (refer FIG. 1) side via the suction pipe 18a with a carbon dioxide.

  The motor chamber 19b in the sealed container 19 contains a motor 20 (electric motor). The motor 20 rotates the crankshaft 15 at a constant speed or at a rotation speed corresponding to a voltage controlled by an inverter (not shown). The turning scroll 14 is turned by the rotating crankshaft 15. Incidentally, the stator (not shown) of the motor 20 is provided with an insulating film in the slot around which the magnet wire is wound. The insulating film in this embodiment is formed of an ester resin.

  Further, an oil sump 24 is provided in the lower part of the discharge pipe 18b in the sealed container 19, and a refrigerating machine oil 21 to be described later is stored in the oil sump 24. The refrigerating machine oil 21 passes through an oil hole 22 provided in the crankshaft 15 due to a pressure difference, and is used for lubricating the sliding portion between the orbiting scroll 14 and the crankshaft 15, the sliding bearing 23, and the like. The refrigerating machine oil 21 is added with an antifoaming agent described later.

The refrigerating machine oil 21 used in the refrigerant compressor 1A according to the present embodiment (hereinafter, may be simply referred to as “refrigerating machine oil” is represented by the following formula (1) or the following formula (2). An antifoaming agent is added to at least one polyol ester.
C- (CH ₂ OCOR) ₄ (1)
(R—COOCH ₂ ) ₃ —C—O—C— (CH ₂ OCO—R) ₃ (2)
(However, in said Formula (1) and said Formula (2), R represents a C11-C19 alkyl group independently)

As such a polyol ester, a hindered type synthesized from a polyhydric alcohol and a monovalent fatty acid and excellent in thermal stability is preferable.
Examples of the polyhydric alcohol include pentaerythritol and dipentaerythritol.
Examples of monovalent fatty acids include those having 12 to 20 carbon atoms, specifically, for example, n-dodecanoic acid, n-tridecanoic acid, n-tetradecanoic acid, n-pentadecanoic acid, n-hexadecanoic acid. N-heptadecanoic acid, n-octadecanoic acid, n-nonadecanoic acid, n-eicosanoic acid, i-dodecanoic acid, i-tridecanoic acid, i-tetradecanoic acid, i-pentadecanoic acid, i-hexadecanoic acid, i-heptadecanoic acid I-octadecanoic acid, i-nonadecanoic acid, i-eicosanoic acid and the like. Moreover, these fatty acids can be used individually or in mixture of 2 or more types.

Such a polyol ester preferably has a kinematic viscosity (measured according to JIS K 2283) in the range of 10 to 30 mm ² / sec at 100 ° C. Incidentally, a polyol ester having a kinematic viscosity of 10 mm ² / sec or more does not decrease the kinematic viscosity excessively even when carbon dioxide is dissolved, and the oil film is sufficiently formed at the sliding portion, and the lubricity is good. Become. In addition, the polyol ester having a kinematic viscosity in such a range exhibits a good sealing property against carbon dioxide having a large diffusion coefficient in the compressor part C (see FIG. 3).
In addition, a polyol ester having a kinematic viscosity of 30 mm ² / sec or less can maintain good operating efficiency of the refrigerant compressor without increasing mechanical loss such as viscosity resistance and frictional resistance. In addition, a polyol ester having a kinematic viscosity in such a range has good oil return properties. In the refrigerant compressor 1A that uses carbon dioxide as the refrigerant, it is possible to exhibit good lubricity and sealing performance by using a polyol ester of a slightly higher viscosity grade than the refrigerating machine oil combined with the chlorofluorocarbon refrigerant. In addition, it is preferable.

  Further, the polyol ester preferably has a viscosity index (measured in accordance with JIS K 2283) of 120 or more. Incidentally, the viscosity index of the polyol ester in which the alkyl group represented by R in the formula (1) and the formula (2) is less than 11 has a viscosity index of 100 or less. Such a polyol ester having a viscosity index of 120 or more is prevented from staying at a low temperature part of the heat pump cycle and has good oil return properties. In addition, since the viscosity change with temperature is so small that the polyol ester in this embodiment is large, the upper limit of the viscosity index is not defined.

Examples of the antifoaming agent include silicones, esters, alcohols, metal soaps, and mixtures thereof. Of these, silicone-based antifoaming agents, specifically silicone oil, are preferred.
The content of the antifoaming agent is desirably 0.1 to 100 ppm by mass, and more desirably 0.5 to 50 ppm by mass with respect to the total amount of the refrigerating machine oil including the polyol ester and the antifoaming agent. The antifoaming agent here is able to exert a defoaming effect well and is uniformly dissolved in the refrigerating machine oil by being contained in the refrigerating machine oil within such a range.

  The refrigerating machine oil in this embodiment can contain a lubricity improver, an antioxidant, an acid scavenger, a metal deactivator, and the like in addition to the polyol ester and the antifoaming agent. Incidentally, an antioxidant and an acid scavenger can be added in order to prevent hydrolysis of the aforementioned polyol ester. As the antioxidant, DBPC (2,6-di-t-butyl-p-cresol) which is a phenolic antioxidant is preferable. Examples of the acid scavenger include an epoxy acid scavenger and a carbodiimide acid scavenger. Of these, aliphatic epoxy acid scavengers are preferred.

The refrigerant compressor 1A (1B) as described above and the heat pump type water heater S equipped with the refrigerant compressor 1A (1B) have the following operational effects.
The refrigerant compressor 1A (1B) according to the present embodiment uses carbon dioxide as a refrigerant, so that the high-pressure side is about 15 MPa and the low-pressure side is about 3 MPa. ) And a refrigerating machine oil containing at least one polyol ester represented by the formula (2) and an antifoaming agent are used, and good lubricity is exhibited at the sliding portion. More specifically, since this polyol ester exhibits moderate compatibility with carbon dioxide as a refrigerant, it is used in a refrigerant compressor during operation like a conventional refrigerating machine oil (see, for example, Patent Document 2) which is too rich in compatibility. Viscosity is not significantly reduced, and oil film formation at the sliding portion is improved. And the sealing property in the compressor part C also becomes favorable.

  In addition, the polyol ester in the present embodiment is different from the conventional refrigerating machine oil that is too rich in compatibility (see, for example, Patent Document 2), and the amount of the polyol ester sent out together with the refrigerant from the refrigerant compressor 1A (1B) side is The possibility of causing pressure loss without being increased is reduced. And since the polyol ester amount in the carbon dioxide sent out from the refrigerant compressor 1A (1B) side does not increase, it can also avoid that heat exchange efficiency falls significantly.

  Further, the polyol ester in the present embodiment is different from the conventional refrigerating machine oil (see, for example, Patent Document 3, Patent Document 4, and Patent Document 5) in which the compatibility with carbon dioxide is too poor, and the low temperature portion of the heat pump cycle. In this case, the oil does not stay in the tank and exhibits good oil return. Therefore, the amount of refrigerating machine oil in the refrigerant compressor 1A (1B) does not decrease, and the possibility that the wear resistance deteriorates at the sliding portion is reduced.

  Moreover, since the defoamer is added to the polyol ester in the refrigerating machine oil in this embodiment, the carbon dioxide bubbles generated in the polyol ester in a reduced pressure state are immediately extinguished. Therefore, unlike the conventional refrigerating machine oil (for example, refer patent document 2), the refrigerating machine oil in this embodiment may inhibit the oil film formation in a sliding part with the bubble of the carbon dioxide generated in the pressure reduction state. Reduced. As a result, the wear resistance at the sliding portion of the refrigerant compressor 1A (1B) is improved. Further, unlike the conventional refrigeration oil (for example, see Patent Document 2), the refrigerant compressor 1A (1B) is less likely to reduce the compression efficiency of the heat pump cycle due to carbon dioxide bubbles generated in a reduced pressure state. .

  Further, in the refrigerant compressor 1A (1B) according to the present embodiment, the polyol ester represented by the formula (1) or the formula (2) is used as a refrigerating machine oil, so that a conventional refrigerating machine oil (for example, a patent) Compared with the refrigerant compressor using the literature 1, the hydrolyzability of the ester insulating film used in the refrigerant compressor 1A (1B) is suppressed. In addition, since the polyol ester has a relatively large volume resistivity, the refrigerant compressor 1A (1B) according to the present embodiment is electrically compared to a conventional refrigerant compressor (see, for example, Patent Document 1). Excellent insulation. And in the heat pump type water heater S equipped with such a refrigerant compressor 1A (1B), long-term reliability can be ensured.

In addition, this invention is implemented in various forms, without being limited to the said embodiment.
In the above embodiment, the heat pump type hot water heater S equipped with 1A (1B) has been described. However, the refrigerant compressor 1A (1B) of the present invention includes an electric car air conditioner, a room air conditioner, a cold district heating appliance, and a vending machine. It can be suitably used for other refrigeration systems such as hot and cold equipment.

  In the above embodiment, the scroll-type refrigerant compressor 1A (1B) has been described. However, the present invention is not limited to this, and is a refrigerant compressor of another type such as a rotary type or a reciprocating type. May be.

  Moreover, although the said embodiment demonstrated the refrigerant compressor 1A (1B) for horizontal installation, this invention may be a refrigerant compressor for vertical installation.

  Moreover, in the said embodiment, it is the instantaneous type heat pump type hot water heater S which mounted two high output refrigerant compressors 1A and 1B in which leakage current and wear resistance are regarded as important, and has two heat pump cycles. Although what was demonstrated was described, this invention is not limited to this, You may provide one refrigerant compressor.

Next, an embodiment in which the operational effects of the refrigerant compressor of the present invention and the heat pump type water heater equipped with the refrigerant compressor will be described.
Here, first, No. 1 shown in Table 1 is used. 1 to No. A polyol ester (abbreviated as POE in Table 1), a polyalkylene glycol (abbreviated as PAG in Table 1), and a poly-α-olefin (abbreviated as PAO in Table 1) as compounds up to 7 were prepared. . And when measuring the density (g / cm < ³ >) in 15 degreeC of the compound shown in Table 1, kinematic viscosity (mm < ² > / sec) in 40 degreeC and 100 degreeC, and a viscosity index | exponent, and using these as refrigerating machine oil The oil film forming property, sealing property, viscous resistance, and oil return property were evaluated. The results are shown in Table 1. The density was measured according to JIS K 2249 “crude oil and petroleum products—density test method and density / mass / capacity conversion table”, Annex 1 (memory test method for I-shaped float).

  In Table 1, No. 1-No. No. 5 polyol ester (POE), and No. 5 The polyalkylene glycol (PAG) 6 is represented by the following chemical formula. In Table 1, No. As described above, 7 is a polyalphaolefin (PAO).

No. 1:
Polyol ester represented by the following formula (1) C— (CH ₂ —O—CO—R ² ) ₄ ... (1)
(Wherein R ² represents an alkyl group having 17 and 15 carbon atoms)

No. 2:
Polyol ester represented by the following formula (2) C— (CH ₂ —O—CO—R ² ) ₄ ... (1)
(Wherein R ² represents an alkyl group having 7 and 8 carbon atoms)

No. 3:
Mixture of polyol esters represented by the following formula (1) and the following formula (2) C— (CH ₂ —O—CO—R ² ) ₄ ... (1)
O— (CH ₂ —C— (CH ₂ —O—CO—R ² ) ₃ ) ₂ ... (2)
(Wherein R ² represents an alkyl group having 7 and 8 carbon atoms)

No. 4:
Mixture of polyol esters represented by the following formula (1) and the following formula (2) C— (CH ₂ —O—CO—R ² ) ₄ ... (1)
O— (CH ₂ —C— (CH ₂ —O—CO—R ² ) ₃ ) ₂ ... (2)
(Wherein R ² represents an alkyl group having 17 and 15 carbon atoms)

No. 5:
Mixture of polyol esters represented by the following formula (1) and the following formula (2) C— (CH ₂ —O—CO—R ² ) ₄ ... (1)
O— (CH ₂ —C— (CH ₂ —O—CO—R ² ) ₃ ) ₂ ... (2)
(Wherein R ² represents an alkyl group having 17 and 15 carbon atoms)

No. 6:
Polyalkylene glycol represented by the following formula (3) CH ₂ O— (C (CH ₃ ) HCH ₂ O) _n —CH ₃ ... (3)
(Average molecular weight Mw is about 1600)

Incidentally, the evaluation of oil film forming property, sealing property, viscous resistance, and oil return property was performed according to the following criteria.
(Oil film forming and sealing properties)
A compound having a kinematic viscosity at 100 ° C. of 10 mm ² / sec or more and a viscosity index exceeding 120 is marked as “◎” in Table 1 because the oil film forming property and the sealing property are very good. In Table 1, “◯” indicates that the oil film forming property and the sealing property of a compound having a kinematic viscosity at 100 ° C. of 10 mm ² / sec or more and a viscosity index of less than 120 are good. And, the kinematic viscosity at 100 ° C. is in the vicinity of 10 mm ² / sec and the viscosity index is in the vicinity of 120. did.
(Viscous resistance)
Those having a kinematic viscosity at 100 ° C. of less than 30 mm ² / sec were marked as “◎” in Table 1 because the viscosity resistance was very good. And the thing of 30 mm < ² > / sec or more was described as "(triangle | delta)" in Table 1 because viscous resistance was normal.
(Oil return)
Polyol ester (POE) that is compatible with carbon dioxide and whose viscosity index exceeds 120 is marked as “◎” in Table 1 as having a very good oil return property, and has a viscosity index of around 90 Is marked as “◯” in Table 1 because the oil return is good. Poly alpha olefin (PAO) is indicated as “x” in Table 1 because it is poorly compatible with carbon dioxide. In addition, about polyalkylene glycol (PAG), the oil return property was equivalent to the polyol ester (POE) whose viscosity index exceeds 120.
(Evaluation of polyol ester)
The polyol ester as the refrigerating machine oil preferably has a kinematic viscosity at 100 ° C. of 10 to 30 mm ² / sec and a viscosity index of 120 or more.

(Example 1 to Example 6)
In Examples 1 to 6, the compound Nos. A refrigerating machine oil was prepared by adding silicone oil as an antifoaming agent to the polyol ester 1 in the amount shown in Table 2.

  And these foaming machine oils evaluated the antifoaming property and solubility. The results are shown in Table 2. The defoaming property and solubility test were performed in accordance with JIS K 2518 “Lubricating Oil Foaming Test Method”.

(Determination criteria for defoaming and solubility)
The defoaming property of the refrigerating machine oil was marked as “◎” as being very good when the foam on the liquid surface was hardly formed, and marked as “◯” as being good when the foam was slightly generated. The solubility of the refrigerating machine oil is described as “◎” as very good when the antifoam is sufficiently dissolved, and as “Good” when the antifoam is slightly deposited. did.

(Evaluation results of defoaming and solubility of refrigerating machine oil)
As is clear from Table 2, it was found that the refrigerating machine oil containing the antifoaming agent at 0.1 to 100 mass ppm can exhibit the antifoaming effect well and dissolve the antifoaming agent uniformly. .

(Example 7 and Comparative Example 1)
In Example 7, the compound No. 1 in Table 1 described above was used. A refrigerating machine oil was prepared by adding silicone oil as an antifoaming agent to 1 polyol ester. The content of silicone oil in the refrigerating machine oil was 10 mass ppm.
About this refrigerating machine oil, the heating test by the following autoclaves was done and the degree of deterioration of refrigerating machine oil was judged. By the way, the next test is an accelerated test, which corresponds to 15 years or more when converted into actual operating years.
In this heating test, 40 g of prepared refrigerating machine oil, 40 g of carbon dioxide, and catalyst (iron, copper, and aluminum) were put in a pressure vessel (200 mL) made of SUS, and heated at 175 ° C. under a pressure of 15 MPa. . The moisture content of the pressure vessel was 50 ppm. Then, after heating for 7 days and after heating for 21 days, the hue (ASTM), acid value, catalyst change, and foamability of the contents were evaluated. The evaluation results are shown in Table 3.

  The hue (ASTM) was measured according to JIS K 2580 “Petroleum products—color test method”. The acid value was measured according to the 5.1.2 potentiometric titration method defined in JIS K 2501 “Petroleum product neutralization number test method”. Regarding the change in the catalyst, the case where the appearance of the catalyst did not change was indicated as “◯”, and the case where there was a change was indicated as “X”. For the foaming property, the content was evacuated in a desiccator, and “O” was given when there was almost no foaming, and “X” was given when it was vigorously foamed.

  In Comparative Example 1, a refrigerating machine oil was prepared in the same manner as in Example 7 except that no antifoaming agent was added to the polyol ester, and a heating test using an autoclave was conducted in the same manner as in Example 7. The results are shown in Table 3.

(Evaluation result of heating test)
As shown in Table 3, the refrigerating machine oils prepared in Example 7 and Comparative Example 1 showed no change in the hue, acid value, appearance of changes in catalyst, etc. even after the above heating, and the defoaming It was confirmed that the agent had no effect on the refrigerating machine oil. And although the refrigerating machine oil of Example 7 containing an antifoamer did not recognize foaming property, the refrigerating machine oil of the comparative example 1 which does not contain an antifoaming agent recognized foaming property.

(Example 8, and Comparative Examples 2 and 3 (see FIGS. 4 and 5))
In Example 8, the compound No. 1 in Table 1 described above was used. A refrigerating machine oil was prepared by adding silicone oil as an antifoaming agent to polyol ester 1 (viscosity index (VG) 150). The content of silicone oil in the refrigerating machine oil was 10 mass ppm.
The volume resistivity (Ω · cm) and dielectric constant (F · m ⁻¹ ) of this refrigerator oil were measured. These measurement tests were performed in accordance with a dielectric breakdown voltage test and a volume resistivity measurement test specified in JIS C 2101 “Electrical insulating oil test method”. The results are shown in FIGS. 4 (a) and (b). 4A is a graph showing the volume resistivity (Ω · cm) on the vertical axis, and FIG. 4B is a graph showing the dielectric constant (F · m ⁻¹ ) on the vertical axis. Incidentally, in FIG. 4A, the level with a volume resistivity of 10 ¹³ Ω · cm is a reference value of the standard of the Electrical Appliance and Material Safety Law.

In Comparative Example 2, a polyol ester of a pentaerythritol / dipentaerythritol mixed system, which is a polyol ester (viscosity index (VG) 220) of a branched chain fatty acid having 18 carbon atoms and a linear fatty acid having 16 carbon atoms. Except for the above, a refrigerating machine oil was prepared in the same manner as in Example 8. Then, the volume resistivity (Ω · cm) and the dielectric constant (F · m ⁻¹ ) of this refrigerator oil were measured in the same manner as in Example 8. The results are shown in FIGS. 4 (a) and (b).

In Comparative Example 3, a refrigerating machine oil was prepared in the same manner as in Example 8 except that polyalkylene glycol (viscosity index (VG) 100) was used instead of the polyol ester. Then, the volume resistivity (Ω · cm) and the dielectric constant (F · m ⁻¹ ) of this refrigerator oil were measured in the same manner as in Example 8. The results are shown in FIGS. 4 (a) and (b).

(Evaluation results of volume resistivity and dielectric constant)
As shown in FIGS. 4A and 4B, the volume resistivity of the refrigerating machine oil of Example 8 is as high as 10 ¹⁵ Ω · cm, which is the standard of the Electrical Appliance and Material Safety Law (reference value of 10 ¹³ Ω · cm or more). It was 10,000 times or more of the refrigerating machine oil containing the polyalkylene glycol of Comparative Example 3. Regarding the dielectric constant, Example 8 was the lowest and was about ½ times that of Comparative Example 3. Moreover, the refrigerating machine oil containing the polyol ester of Comparative Example 2 had a lower volume resistivity and a higher dielectric constant than the refrigerating machine oil of Example 8.
From the above, it has been found that the refrigerating machine oil of Example 8 containing the predetermined polyol ester described above has excellent electrical characteristics and can contribute to reduction of leakage current even when incorporated in a product.

(Evaluation of lubricity)
Next, the lubricity of the refrigerating machine oils prepared in Example 8, Comparative Example 2, and Comparative Example 3 was evaluated. The evaluation of lubricity here was performed by measuring the seizure load (N) and the amount of wear (μm) in accordance with ASTM D3233 “Farex Lubrication Characteristics Test Method” for each refrigerating machine oil. The results are shown in FIGS. 5 (a) and (b). 5A is a graph showing the seizure load (N) on the vertical axis, and FIG. 5B is a graph showing the amount of wear (μm) on the vertical axis. Note that the seizure load (N) was measured by a continuous load method, and carbon dioxide was sprayed onto the sliding portion under the condition of 150 mL / min. The amount of wear was measured at a load of 445 N, a temperature of 120 ° C., and a sliding time of 3 hours, and carbon dioxide was sprayed onto the sliding part at 150 mL / min.
In FIG. 5 (a), the seizure load (N) when a refrigerating machine oil further containing an extreme pressure additive (tricresyl phosphate) is used in the refrigerating machine oil of Comparative Example 3 is also shown as a reference example.
Further, in FIG. 5 (b), the amount of wear (μm) when using the refrigerating machine oil of Example 2 and the refrigerating machine oil further containing an acid scavenger is shown together as Example 9.

  As shown in FIG. 5 (a), the refrigerating machine oil of Example 8 has a larger seizure load (N) than the refrigerating machine oil of Comparative Example 3 containing polyalkylene glycol. A large seizure load (N) equivalent to that of the refrigerating machine oil of the reference example to which the extreme pressure additive was added was shown. Incidentally, since the refrigerating machine oil containing the polyol ester of Comparative Example 2 is a polyol ester of a pentaerythritol / dipentaerythritol mixed system, the seizure load (N) is smaller than that of the refrigerating machine oil of Example 8. .

And as shown in FIG.5 (b), the amount of abrasion (micrometer) of the refrigerator oil of Example 9 which added the acid scavenger further to the refrigerator oil of Example 8 was the least. Moreover, even if it is the refrigerating machine oil of Example 8 which does not contain an acid scavenger, it will become a small amount of wear (micrometer) equivalent to the refrigerating machine oil of the reference example which added the extreme pressure additive to the refrigerating machine oil of the comparative example 3. It was.
From the above, the refrigerating machine oil of Example 8 (Example 9) containing the predetermined polyol ester described above is excellent in terms of lubricity, and the compressor part C (see FIG. 3) even when incorporated in a product. It was found that it can contribute to the reduction of the amount of wear (μm).

It is composition explanatory drawing of the heat pump type water heater by which the refrigerant compressor concerning an embodiment is carried. It is a conceptual diagram which shows arrangement | positioning of the refrigerant | coolant compressor, the water refrigerant | coolant heat exchanger, the air side heat exchanger, the hot water storage tank, and the ventilation fan in the heat pump type water heater of FIG. 1, Comprising: It is the side view seen from the ventilation fan side. . It is sectional drawing of the refrigerant compressor which concerns on embodiment. (A) is a graph which shows volume resistivity (ohm * cm) on a vertical axis | shaft, (b) is a graph which shows dielectric constant (F * m ^<-1> ) on a vertical axis | shaft. (A) is a graph showing the seizure load (N) on the vertical axis, and (b) is a graph showing the wear amount (μm) on the vertical axis.

Explanation of symbols

1A Refrigerant compressor 1B Refrigerant compressor 2 Water refrigerant heat exchanger 9 Fixed scroll 14 Orbiting scroll 15 Crankshaft (rotating shaft)
19 Sealed container 20 Motor S Heat pump water heater C Compressor part

Claims (6)

In a refrigerant container that stores a motor and a compressor unit that compresses refrigerant by being connected to the motor via a rotating shaft in a sealed container for storing refrigerating machine oil,
The refrigerant is carbon dioxide, and the refrigerant compressor is at least one polyol ester represented by the following formula (1) and formula (2) containing an antifoaming agent as the refrigerating machine oil.
C- (CH ₂ OCOR) ₄ (1)
(R—COOCH ₂ ) ₃ —C—O—C— (CH ₂ OCO—R) ₃ (2)
(However, in said Formula (1) and said Formula (2), R represents a C11-C19 alkyl group independently) ^2. The refrigerant compressor according to claim 1, wherein the polyol ester has a kinematic viscosity (100 ° C.) of 10 to 30 mm ² / sec and a viscosity index of 120 or more.   The refrigerant compressor according to claim 1, wherein the antifoaming agent is a silicone-based antifoaming agent.   The refrigerant compressor according to claim 1, wherein the content of the antifoaming agent in the refrigerating machine oil is 0.1 to 100 ppm by mass.   A heat pump type hot water heater comprising the refrigerant compressor according to claim 1.   The heat pump type hot water heater according to claim 5, wherein the two refrigerant compressors are operated in parallel to form two heat pump cycles.

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