JPH10204458A - Refrigerator oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refrigerator oil, capable of maintaining the durability of a compressor without depositing an oligomer or a carboxylic acid metallic salt, etc., dissolved in a refrigerator oil ever when a nonester-based low-viscosity refrigerator oil is applied to a reciprocating hermetically closed type electric compressor in order to raise the efficiency and prevent hydrolysis. SOLUTION: A refrigerator oil, consisting essentially of a nonester-based synthetic oil having <=20mm<2> /sec kinematic viscosity at 40 deg.C and containing >=20wt.% component having 1400 deg.C boiling point compounded therewith can be used to thereby maintain the durability of a compressor without depositing an oligomer or a carboxylic acid metallic salt, etc., near a discharging chamber or a discharging valve due to no complete evaporation of the component having >=400 deg.C boiling point in the refrigerator oil in the discharging chamber and due to the discharge together with the refrigerant while dissolving the oligomer or carboxylic acid metallic salt therein. A carbonate-based synthetic oil or an ether-based synthetic oil is preferred as the nonester-based synthetic oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating machine oil used for a refrigerating cycle of a refrigerator, a home air conditioner and the like.

[0002]

2. Description of the Related Art At present, from the viewpoint of protection of the ozone layer, replacement of a refrigerant in a refrigeration cycle and improvement in efficiency of a compressor for a refrigeration cycle are being promoted. In this process, when a conventional chlorine-containing refrigerant is changed to a chlorine-free hydrofluorocarbon (hereinafter referred to as HFC) -based alternative refrigerant, a refrigeration mainly containing an ester, ether, or carbonate that is compatible with the refrigerant. A refrigerating machine oil mainly containing a machine oil or an incompatible alkylbenzene is used.
On the other hand, studies have been made to reduce the viscosity of these refrigerating machine oils in order to increase the efficiency.

However, ester-based oils generate carboxylic acids by hydrolysis or thermal decomposition, and have a disadvantage in that metal corrosion or copper plating occurs due to carboxylic acids. You need to be careful.

[0004] On the other hand, carbonate-based oils and ether-based oils have improved weaknesses of generating carboxylic acids by hydrolysis or thermal decomposition of ester-based oils (for example, JP-A-7-224290 and JP-A-6-345679). ).

An example of a conventional compressor using a low-viscosity non-ester type refrigerating machine oil will be described below with reference to the drawings.

[0007] For example, a conventional compressor shown in FIG. 7 includes an electric element 2 and a compression element 3 elastically supported in a closed container 1, and transmits the torque of the electric element 2. The compression element 3 includes a crankshaft 4, a connecting rod 5, and a piston 6. Reference numeral 7 denotes a cylinder head. A capillary tube 15 is press-fitted and fixed to the cylinder head 7 via a plug 17, and one end of the capillary tube 15 has a kinematic viscosity at a boiling point of 300 ° C. and 40 ° C. of 8 mm.
^The other end is open to the suction chamber 8 of the cylinder head 7 below the oil level of the ² / s ether-based refrigerating machine oil 16.

The operation of the compressor configured as described above will be described below. The rotational force of the electric element 2 reciprocates the piston 6 via the crankshaft 4 and the connecting rod 5 to suck and compress the HFC gas.
The HFC gas flows from the suction chamber 8 of the cylinder head 7 through the suction hole 11 of the valve plate 10 to the cylinder 13.
Is guided to the cylinder chamber 14 and compressed.

At a high temperature, the compressed HFC gas is sent to the discharge chamber 9 of the cylinder head 7 through the discharge holes 12 of the valve plate 10.

Due to the flow of the HFC gas as described above, the pressure in the suction chamber 8 becomes lower than the atmospheric pressure in the closed vessel 1, and an appropriate amount of the refrigerating machine oil 16 is supplied by the capillary tube 15 fixed to the cylinder head 7. Into the suction chamber 8 and finally the cylinder chamber 14
The refrigerating machine oil 16 is sent to the refrigerating machine oil 16, and the refrigerating machine oil 16 evaporates, thereby reducing the discharge gas temperature.
And the sealing property is improved.

[0010]

However, in the above-mentioned conventional construction, the refrigerating machine oil supplied into the cylinder chamber evaporates in the discharge chamber due to the low boiling point of the oil. The polyester oligomer of the material and the metal carboxylate in the processing oil are precipitated, and the discharge chamber may be blocked or the discharge valve may operate improperly.

Therefore, even when a non-ester type low-viscosity refrigerating machine oil is applied to a reciprocating hermetic electric compressor for higher efficiency and prevention of hydrolysis, oligomers and carboxylic acids dissolved in the refrigerating machine oil are used. There is a demand for a high boiling point refrigerating machine oil capable of maintaining performance without depositing metal salts and the like.

The present invention improves the evaporation characteristics of refrigerating machine oil,
An object of the present invention is to improve the durability of a compressor by preventing precipitation of oligomers, metal carboxylate, and the like dissolved in refrigerator oil.

[0013]

Accordingly, the refrigerating machine oil of the present invention comprises a non-ester synthetic oil having a kinematic viscosity at 40 ° C. of 20 mm ² / s or less as a main component and a component having a boiling point of 400 ° C. or more.
0% by weight or more is blended.

According to the present invention, in the reciprocating hermetic electric compressor, components having a boiling point of 400 ° C. or higher in the refrigerating machine oil do not completely evaporate in the discharge chamber, and the oligomer and the metal carboxylate remain dissolved in the discharge chamber. Since the refrigerant is discharged together with the refrigerant, the durability of the compressor can be maintained without depositing oligomers, metal carboxylate, and the like near the discharge chamber and the discharge valve.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The first aspect of the present invention is a refrigerating machine oil used for a reciprocating hermetic electric compressor for compressing an HFC refrigerant, which has a kinematic viscosity at 40 ° C. of 20 m.
m ² / s or less of a carbonate-based synthetic oil or an ether-based synthetic oil as a main component, and a component having a boiling point of 400 ° C. or more.
A refrigerating machine oil characterized by being blended in an amount of 0% by weight or more, which can improve the efficiency of the compressor, does not cause hydrolysis, and precipitates oligomers and metal carboxylate in the vicinity of a discharge chamber or a discharge valve. This has the effect that the durability of the compressor can be maintained without performing.

The invention according to claim 2 of the present invention provides an HFC
A refrigerating machine oil used for a reciprocating hermetic electric compressor for compressing a system refrigerant, wherein the kinematic viscosity at 40 ° C. is 20 mm ² / s.
The following alkylbenzene oils are the main components and the boiling point is 400
A refrigerating machine oil characterized by containing 20% by weight or more of a component having a temperature of at least 100 ° C., which is inexpensive, has high efficiency of a compressor, does not cause hydrolysis, and has oligomers near a discharge chamber or a discharge valve. And the effect that the durability of the compressor can be maintained without precipitation of metal salts of carboxylic acid and the like. Also, since the alkylbenzene oil is incompatible with the HFC refrigerant, the refrigerant phase and the refrigerating machine oil phase are separated in the refrigeration system, and the metal carboxylate and the like are circulated in the refrigeration system while being dissolved in the oil. In addition, there is an effect that the durability of the refrigeration system can be maintained without depositing metal carboxylate or the like in the piping.

According to a third aspect of the present invention, there is provided the
Reciprocating hermetic electric compressor that compresses carbon-based refrigerant
A kinetic viscosity at 40 ° C. of 20
mm ²/ S or less alkylbenzene oil as the main component,
20% by weight or more of components with a temperature of 400 ° C or higher
A refrigerating machine oil characterized by low cost, high efficiency of compressor
Efficiency, hydrolysis does not occur, and discharge
Oligomer or metal carboxylate in the chamber or near the discharge valve
A product that can maintain the durability of the compressor without precipitation
Having The HC refrigerant has a global warming potential of HFC
Because it is significantly smaller than refrigerant, it works to reduce global warming.
Having

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a refrigerating machine oil according to an embodiment of the present invention.

(Embodiment 1) FIG. 1 is a diagram showing a relationship between an evaporation amount of a refrigerating machine oil and a distillation temperature used in a reciprocating hermetic electric compressor for compressing an HFC refrigerant according to a first embodiment of the present invention. is there. FIG. 2 is a graph showing the relationship between the temperature of the gas discharged from the refrigerating machine oil of the embodiment and the amount of oligomer precipitated. The reciprocating hermetic electric compressor for compressing the HFC refrigerant according to the first embodiment of the present invention is the same as the conventional hermetic electric compressor shown in FIG. .

1 and 2, the ether type oil A according to the first embodiment of the present invention has, for example, a conventional structure having a structure of (Chemical Formula 1) having a boiling point of 300 ° C., a kinematic viscosity at 40 ° C. of 8 mm ² / s. 20% by weight of an ether oil B having a boiling point of 400 ° C. and a kinematic viscosity of 50 mm ² / s at 40 ° C. and a kinematic viscosity of 10 mm ² / s at 40 ° C.

[0021]

Embedded image

In the above (Chemical formula 1), R1 and R2
Is an independent hydrocarbon group. Further, n is an integer.

In FIG. 1, since the ether oils B and C, which are components of the ether oil A according to the first embodiment of the present invention, are single components, the distillation temperature is constant. The ether oil A has a boiling point of 80% by weight or more and shows the boiling point of the ether oil C by mixing 20% by weight of the ether oil C with the ether oil B, so that the ether refrigeration has a high boiling point and a low viscosity. Machine oil can be obtained.

However, the evaporation temperature does not suddenly change from the boiling point of ether oil B of 300 ° C. to the boiling point of ether oil C of 400 ° C. when the amount of evaporation is 80% by weight.
When the evaporation amount is 80 to 90% by weight, the boiling point of the ether oil C is 4
Does not reach 00 ° C. Therefore, in order to set the temperature at which the ether-based oil A completely evaporates to 400 ° C., the blending amount of the ether-based oil is 20% by weight or more.

In FIG. 2, the ester oil A has a boiling point of 370.
The kinematic viscosity at 40 ° C. and 8 ° C. is 8 mm ² / s. The boiling point of the ester oil B is 480 ° C. and the kinematic viscosity at 40 ° C. is 45 mm ² / s. Since ester-based oils undergo hydrolysis, care must be taken in temperature control. However, even if the kinematic viscosity is low, the boiling point becomes higher due to a stronger intermolecular force than the ether-based oils and carbonate-based oils in terms of molecular structure. Therefore, the amount of oligomer deposited is small, and there is no problem such as blockage of the discharge chamber or malfunction of the discharge valve in the case of ester-based oil.

From FIG. 2, it can be seen that the ether oil B of the conventional specification has a large amount of oligomer precipitated. On the other hand, the ether-based oil A of Example 1 of the present invention has a remarkably reduced oligomer precipitation amount as compared with the ether-based oil, and it can be seen that the durability equivalent to the ester-based oil can be maintained.

The reason why the amount of oligomers precipitated from the ether oil A was remarkably reduced is that the components having a boiling point of 400 ° C. in the ether oil A did not completely evaporate in the discharge chamber and dissolved the oligomers and metal carboxylate. This is because it is discharged together with the refrigerant as it is.

In place of the ether-based oil, a carbonate-based oil having, for example, the structure of Chemical Formula 2 may be used.

[0029]

Embedded image

In the above (Chemical formula 2), R3 and R4
Is an independent hydrocarbon chain.

(Embodiment 2) FIG. 3 is a diagram showing the relationship between the evaporation amount of refrigerating machine oil and distillation temperature used in a reciprocating hermetic electric compressor for compressing HFC refrigerant according to Embodiment 2 of the present invention. is there. FIG. 4 is a graph showing the relationship between the temperature of the gas discharged from the refrigerating machine oil of the embodiment and the amount of oligomer precipitated. The reciprocating hermetic electric compressor for compressing the HFC refrigerant according to the second embodiment of the present invention is the same as the conventional hermetic electric compressor shown in FIG. .

The low-viscosity alkylbenzene-based oil has a low boiling point like the conventional low-viscosity ether-based oil, and the refrigerating machine oil supplied into the cylinder chamber evaporates in the discharge chamber. Polyester oligomer of motor insulation material and metal carboxylate in processing oil are precipitated,
The discharge chamber may be blocked or the discharge valve may operate improperly, resulting in a significant decrease in performance.

3 and 4, the alkylbenzene-based oil A of Example 2 of the present invention has an evaporation temperature of 330 ° C. when evaporated at 80% by weight and a kinematic viscosity at 40 ° C. of 8 mm ² /.
The evaporation temperature when evaporating 80% to the alkylbenzene-based oil B of s is 410 ° C., and the kinematic viscosity at 40 ° C. is 50 mm ² /
s of alkylbenzene-based oil C having a kinematic viscosity of 15 mm ² / s at 40 ° C. Since the alkylbenzene-based oil and the HFC refrigerant are incompatible, if the boiling point of the alkylbenzene-based oil C is too high, the kinematic viscosity increases accordingly.

It is conceivable that only the alkylbenzene-based oil C stays in the evaporator and does not return to the compressor due to the kinematic viscosity of the alkylbenzene-based oil C further increasing in the evaporator section, which becomes extremely low in the refrigerating cycle.
Therefore, it is preferable to reduce the kinematic viscosity as much as possible and increase the blending amount of the alkylbenzene-based oil C as long as the component having a boiling point of 400 ° C. or higher is present in an amount of 20% by weight or higher.

In FIG. 3, the distillation curve of the alkylbenzene-based oil rises to the right because it is a mixture of several components. The alkylbenzene-based oil A of Example 2 of the present invention follows the distillation curve of the alkylbenzene-based oil B up to the blending ratio of 60% by weight, and approaches the distillation curve of the alkylbenzene-based oil C after 60% by weight.

However, the distillation temperature does not suddenly change from a boiling point of 320 ° C. when the alkylbenzene oil B is 60% by weight to a boiling point of 400 ° C. when the alkylbenzene oil C is 60% by weight. % Approaches the boiling point of the alkylbenzene oil C.

This is because the alkylbenzene oil B is a mixture of several components.
In order to raise the temperature at which the oil completely evaporates to 400 ° C. or higher, the blending amount of the alkylbenzene oil C must be 40% by weight or more.

From FIG. 4, it can be seen that the low viscosity alkylbenzene-based oil B has much oligomer precipitation. On the other hand, the alkylbenzene-based oil A of the present invention has a significantly reduced oligomer precipitation amount as compared with the alkylbenzene-based oil B, and it can be seen that the durability equivalent to the ester-based oil can be maintained. The amount of oligomer precipitation of the alkylbenzene oil A was remarkably reduced because the components having a boiling point of 400 ° C. or higher in the alkylbenzene oil A did not completely evaporate in the discharge chamber, and the refrigerant was dissolved while the oligomer and metal carboxylate were dissolved. This is because the ink is discharged together with the ink.

Further, the alkylbenzene oil A is HFC
The refrigerant phase and the refrigerating machine oil phase are separated in the refrigeration system because they are incompatible with the refrigerant, and the metal carboxylate circulates through the refrigeration system while being dissolved in the oil. The durability of the refrigeration system can be maintained without depositing metal salts and the like.

(Embodiment 3) FIG. 5 shows the relationship between the evaporation amount of the refrigerating machine oil and the distillation temperature used in a reciprocating hermetic electric compressor for compressing a hydrocarbon (hereinafter referred to as HC) refrigerant according to a third embodiment of the present invention. FIG. 3 is a diagram showing the relationship. FIG. 6 is a diagram showing the relationship between the temperature of the gas discharged from the refrigerating machine oil of the embodiment and the amount of oligomer precipitated. The reciprocating hermetic electric compressor for compressing HC refrigerant according to the third embodiment of the present invention is
Except for the above, it is the same as the conventional hermetic electric compressor shown in FIG.

In FIGS. 5 and 6, the alkylbenzene-based oil D of Example 3 of the present invention has a kinematic viscosity at 330 ° C. and 40 ° C. of 8 mm ² / evaporated at 80% by weight.
s, and the kinematic viscosity at a temperature of 430 ° C. and 40 ° C. of 65 mm ² /
s of alkylbenzene-based oil F of 20% by weight, and has a kinematic viscosity of 12 mm ² / s at 40 ° C.

In the third embodiment of the present invention, unlike the second embodiment of the present invention, since the alkylbenzene oil is compatible with the HC refrigerant, the high-viscosity alkylbenzene-based oil F does not stay in the evaporator section where the temperature becomes low in the refrigeration system. Come back to the compressor. Therefore, the boiling point of the alkylbenzene-based oil F is 4
It is not necessary to lower the kinematic viscosity as much as possible and increase the blending amount as long as the component having a temperature of 00 ° C. or more is present in an amount of 20% by weight or more.

In FIG. 5, the distillation curve of the alkylbenzene-based oil rises to the right because it is a mixture of several components. The alkylbenzene-based oil D of Example 3 of the present invention follows the distillation curve of the alkylbenzene-based oil E up to the blending ratio of 80% by weight, and approaches the distillation curve of the alkylbenzene-based oil F after 80% by weight.

However, the distillation temperature does not suddenly change from a boiling point of 330 ° C. when the alkylbenzene oil E is 80% by weight to a boiling point of 430 ° C. when the alkylbenzene oil F is 80% by weight. % Approaches the boiling point of the alkylbenzene oil F.

This is because the alkylbenzene oil B is a mixture of a number of components.
In order to make the temperature at which the water completely evaporates to 400 ° C. or higher, the amount of the alkylbenzene-based oil F needs to be 20% by weight or more.

FIG. 6 shows that the alkylbenzene oil E having a low viscosity has a large amount of oligomer precipitated. On the other hand, the alkylbenzene-based oil D of the present invention has a significantly reduced amount of oligomers compared to the alkylbenzene-based oil E, and it can be seen that durability equivalent to that of the ester-based oil can be maintained.

The reason why the amount of oligomers of the alkylbenzene-based oil D precipitated was remarkably reduced is that the components having a boiling point of 400 ° C. or higher in the alkylbenzene-based oil D did not completely evaporate in the discharge chamber and dissolved oligomers and metal carboxylate. This is because the refrigerant is discharged together with the refrigerant.

Further, the HC refrigerant has a global warming potential of HF.
Since it is significantly smaller than the C refrigerant, it has an effect of suppressing global warming. Note that mineral oil may be used instead of the alkylbenzene-based oil.

[0049]

As described above, according to the present invention, even when a non-ester type low viscosity refrigerating machine oil is applied to a reciprocating hermetic electric compressor for high efficiency and prevention of formation of hydrolyzed water, the refrigerating system can be used. Components having a boiling point of 400 ° C or higher in the machine oil do not completely evaporate in the discharge chamber, but are discharged together with the refrigerant while dissolving the oligomers and metal carboxylate. The effect is obtained that the durability of the compressor can be maintained without the precipitation of salts and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing a distillation curve of an ether oil.

FIG. 2 is a graph showing the relationship between the discharge temperature of ether-based oil and the amount of oligomer precipitation.

FIG. 3 is a diagram showing a distillation curve of an alkylbenzene-based oil.

FIG. 4 is a graph showing the relationship between the discharge temperature of an alkylbenzene-based oil and the amount of precipitated oligomers.

FIG. 5 is a diagram showing a distillation curve of an alkylbenzene-based oil.

FIG. 6 is a graph showing the relationship between the discharge temperature of an alkylbenzene-based oil and the amount of oligomers precipitated.

FIG. 7 is a sectional view of a hermetic electric compressor using a conventional low-viscosity refrigeration oil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Closed container 2 Electric element 3 Compression element 4 Crankshaft 5 Connecting rod 6 Piston 8 Suction chamber 9 Discharge chamber 13 Cylinder 14 Cylinder chamber 15 Capillary tube 16 Refrigeration oil

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10N 30:04 40:30

Claims (3)

[Claims] 1. A refrigerating machine oil used for a reciprocating hermetic electric compressor for compressing a hydrofluorocarbon-based refrigerant, wherein a carbonate-based synthetic oil or an ether-based synthetic oil having a kinematic viscosity at 40 ° C. of 20 mm ² / s or less. Refrigeration oil comprising 20% by weight or more of a component having a boiling point of 400 ° C. or higher. 2. A refrigerating machine oil for use in a reciprocating hermetic electric compressor for compressing a hydrofluorocarbon-based refrigerant, which is mainly composed of an alkylbenzene oil having a kinematic viscosity at 40 ° C. of 20 mm ² / s or less and having a boiling point of A refrigerating machine oil comprising a component of 400 ° C. or higher and 20% by weight or more. 3. A refrigerating machine oil used for a reciprocating hermetic electric compressor for compressing a hydrocarbon-based refrigerant,
A refrigerating machine oil comprising, as a main component, an alkylbenzene oil or a mineral oil having a kinematic viscosity at 40 ° C. of 20 mm ² / s or less and a component having a boiling point of 400 ° C. or more at 20% by weight or more.