JPH1129766A - Refrigerator and coolant compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refrigerator oil which can realize use of hydrofluorocarbon coolants and the like, i.e., alternative coolants for Flon 22, and hence can cope with regulation of Flon, and to provide highly reliable coolant compressor and refrigerator, capable of withstanding long-term use by using the refrigerator oil. SOLUTION: An ester oil or an ether oil is added with a reaction product obtained by reacting a part of glycerol with a fatty acid, i.e., the resultant esterified compd. 17 is added thereto. This mixture results in the formation of a chemical adsorption film onto the surface of a sliding section of a vane 10 or the like of a compressor 15, preventing the metal surface from causing direct contact to create seizing or abnormal abrasion. Therefore, highly reliable coolant compressors and refrigerators using the same can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In a refrigeration cycle including a compressor, a condenser, a dryer, an expansion mechanism, and an evaporator, an HFC or HCFC refrigerant compressor having a condenser temperature of 40 ° C. or more incorporates a refrigerating machine oil composition. The present invention relates to a refrigerant compressor and a refrigeration apparatus including the refrigerant compressor, and more particularly to a refrigeration apparatus including a refrigeration oil suitable for increasing the reliability of the compressor with little deterioration even when contacted with a refrigerant at a relatively high temperature. .

[0002]

2. Description of the Related Art Hydrochlorofluorocarbons have been subject to regulation in addition to specific CFCs due to the problem of destruction of the ozone layer in the stratosphere by CFCs. Freon 2 used in refrigeration cycles such as refrigerators and room air conditioners
2 is also subject to regulation. As a substitute, a refrigerant such as R410A, R407C, or R404, which is a hydrofluorocarbon-based compound containing no chlorine in the molecule, such as Freon 32, Freon 125, Freon 134a, Freon 143a, or a mixture of two or more of these. Is mentioned.

[0003] However, these fluorocarbons have very characteristic properties due to their peculiar chemical structure. Mineral oil, a refrigeration oil used in the refrigeration system of Freon 22, and alkylbenzene oil of synthetic oil, etc. The compound of carbon and hydrogen is not compatible with each other, so if oil flows out from the compressor during the refrigeration cycle, oil return will be poor, and oil will stay in the heat exchange equipment and reduce heat transfer performance, There is a problem in that the oil in the compressor runs short on the surface of the iron-based sliding member, and poor lubrication causes seizure or abnormal wear of the sliding portion. Also, when oil and refrigerant are separated in the compressor, a low-viscosity refrigerant layer is supplied due to the pump system that pumps the oil to the sliding part of the compressor from the bottom, and the bearing slides because the oil film thickness is small. Moving parts will be damaged.

[0004] Therefore, there is a need to develop a new refrigerating machine oil as a refrigerant for replacing Freon 22. As a refrigerating machine oil compatible with the alternative refrigerant, an ester oil system containing oxygen in the molecule (Japanese Patent Laid-Open No. 3-1298992, 3-21749)
No. 4, 183,788) and ether oils (JP-A-6-128578, 6-234814) and the like. However, even in such a refrigerating machine oil having good compatibility, the oil film is deficient and seizure of the sliding portion and abnormal wear may occur.

[0005]

In the case of the HFC-based alternative refrigerant, since the refrigerant itself does not contain chlorine, the lubricating property of the sliding portion is lower than that of the conventional system. This allows
There is a problem that seizure or abnormal wear of the sliding portion occurs. Accordingly, a first object of the present invention is to provide a refrigerant compressor filled with a refrigerating machine oil composition having excellent abrasion resistance in the presence of a hydrofluorocarbon-based refrigerant which is a substitute for Freon 22, and a second object of the present invention. Is to provide a refrigerating apparatus provided with the refrigerant compressor.

[0006]

The refrigerating machine oil used in the refrigerating apparatus of the present invention has a structure in which an ester oil or an ether oil is used as a base oil and a part of glycerin is reacted with a fatty acid to esterify the oil. By adding the additive, a chemical adsorption film is formed on the surface of the sliding portion, and it is possible to prevent the metal surface from directly contacting and causing seizure or abnormal wear.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a sectional view of a rotary compressor as a typical refrigerant compressor. Refrigerant compressors used in refrigeration cycles include rotary compressors, scroll compressors, reciprocating compressors, etc. Among them, rotary compressors tend to instantaneously rise in temperature because sliding parts come into point contact, Damage due to burning is easy to occur. In this refrigerant compressor, an electric motor unit 14 and a compressor unit 15 are housed in a closed case 1 also serving as an oil reservoir. Motor unit 1
Reference numeral 4 denotes a rotor 12 and a stator 13, and a rotary shaft 4 made of cast iron is fitted to the rotor 12.

The rotating shaft 4 has an eccentric portion 3 and has a hollow shaft hole 11 at one end. The compressor unit 15 includes a cylinder 2 made of an iron-based sintered body, a cast iron roller 7 eccentrically rotating in the cylinder 2, a tip of which contacts the roller 7, and the other end is pressed by a spring 9 while the groove of the cylinder 2 is formed. A main mechanism element includes a vane 10 reciprocating in the inside 8, and main and sub bearings 5 and 6 of cast iron or iron-based sintered body provided at both ends of the cylinder 2. A refrigerator oil 16 is stored at the bottom, and a compound 17 obtained by reacting a part of glycerin with a fatty acid and esterifying it is added. This refrigerating machine oil is supplied to the sliding portion.

The refrigerant used in the compressor is a non-chlorine refrigerant, and the refrigerating machine oil in this case is an ester oil or an ether oil having good compatibility with the non-chlorine refrigerant. As the refrigerating machine oil, the viscosity at 40 ° C. is 2 to 70 cSt, 100
The refrigerating machine oil having a viscosity at 1 ° C. of 1 to 9 cSt and having excellent refrigerant compatibility is supplied to the sliding portion together with the circulation of the refrigerant, and contributes to lubrication of the sliding portion. Table 1 shows the relationship between the addition of a compound obtained by reacting a part of glycerin with a fatty acid and esterified in a Falex abrasion test and the amount of abrasion and the seizure load.

[0010]

[Table 1]

The test conditions were as follows: refrigeration oil was ester oil (VG32), load 250 lb, time 5 h, rotation speed 290 rpm, temperature 100 ° C., running-in 50 lb, 10 mi
n, a Falex test was performed in an atmosphere air. Under the test conditions described above, when the additive of the present invention, in which a part of glycerin was reacted with oleic acid and esterified, was added at 0.5%, the abrasion loss of the pin + V block was reduced by 38% as compared with the case where no additive was added. Further, according to the Falex seizure test, the seizure load was found to increase by 124 lb with respect to the base oil.

When the properties of this test oil were analyzed, the total acid value of the later oil was lower in all the test pieces when the additive of the present invention was added. In other words, the addition of the additive of the present invention has the effect of reducing heat generation due to local friction because the sliding parts no longer come into direct contact, and has the effect of preventing the refrigerating machine oil from being thermally decomposed. Was.

FIG. 2 shows the test conditions in which the refrigerating machine oil was an ester oil (VG56), the load was 100 lb, and the rotation speed 2 was 5 hours.
90min-1, temperature 120 ℃, break-in operation 50lb, 10mi
n, a Falex test was performed with the atmosphere air, and the relationship between the amount of the additive and the amount of wear was summarized. The horizontal axis indicates the amount of addition, and the vertical axis indicates the amount of wear. Add 0.05wt
% Was not so effective, but 0.1 w
In the case of t%, the amount of wear is greatly improved. Further, a significant improvement effect was obtained up to the addition amount of 1 wt%, but the effect was the same even if added over 1 wt%.

FIG. 3 shows a basic refrigeration cycle configuration diagram. In the refrigeration system including the refrigerant compressor 18, the condenser 19, the dryer 22, the expansion mechanism 20, and the evaporator 21, the refrigerant compressor 18 compresses the low-temperature low-pressure refrigerant gas and discharges the high-temperature high-pressure refrigerant gas to condense. To the vessel 19. The refrigerant gas sent to the condenser 19 becomes a high-temperature and high-pressure refrigerant liquid while releasing its heat into the air, and is sent to the expansion mechanism 20 while the moisture is removed by the dryer 22. The high-temperature and high-pressure refrigerant liquid passing through the expansion mechanism becomes low-temperature and low-pressure wet steam by the throttle effect and is sent to the evaporator 21. The refrigerant that has entered the evaporator 21 absorbs heat from the surroundings and evaporates, and the low-temperature and low-pressure refrigerant gas that has left the evaporator 21 is drawn into the compressor 18, and the same cycle is repeated thereafter. In this cycle, the room air conditioner,
Dehumidifiers require medium evaporator temperatures (-10 ° C or less), while refrigerators require low evaporator temperatures (-30 ° C).
Below).

FIG. 4 shows the compatibility of R410A / refrigeration oil. The horizontal axis indicates the amount of addition, and the vertical axis indicates the two-layer separation temperature. In the current room air conditioner, the two-layer separation temperature is about 8 ° C, so if it is considered to be the same level as the current situation, ester oil (VG56)
Means 2.5 wt% of additive, ether oil (VG68)
Is 3% by weight or less, but when newly considering cold regions, the two-layer separation temperature is preferably -10 ° C or less. Therefore, the addition amount is desirably 0.8 wt% or less in the case of ester oil, and 2 wt% or less in the case of ether oil.

In this case, when used in the refrigerating cycle shown in FIG. 3, the refrigerating machine oil discharged together with the refrigerant gas from the compressor 18 causes a two-layer separation in the evaporator 21 and the refrigerating machine oil is separated from the inner wall of the pipe of the heat exchanger. To the refrigeration oil, causing the stagnation of the refrigerating machine oil and the heat insulation of the heat exchanger, and the additives themselves separate in the low-temperature range, causing the expansion mechanism such as capillaries to clog, thereby impeding the cooling performance of the refrigeration system. It is not practical because it is possible to do so.

Table 2 shows the addition of the above additives and the change in pour point. The test method is based on JIS K2269 "Testing methods for pour point of crude oil and petroleum products and cloud point of petroleum products". When the refrigerating machine oil is cooled at a temperature lower than the pour point in the cycle, the refrigerating machine oil solidifies, the oil is not supplied to the sliding portion, and there is a possibility that damage due to seizure may occur. The additive used in this example has a pour point of 20 ° C., and there is a possibility of increasing the pour point of the refrigerating machine oil by adding it to the refrigerating machine oil. Therefore, the amount of the above additive was changed and added to the ester oil and ether oil, and the pour point was measured. When 4 wt% was added to the ester oil, the pour point increased to −30 ° C. It was confirmed that there was no problem because the temperature was not exceeded.

[0018]

[Table 2]

An acid scavenger added to the refrigerator oil,
Antioxidants and defoamers are, for example, as follows.
The acid scavenger is added in order to remove the ester oil when the acid component is present in the refrigerating machine oil, and the ester oil is decomposed and becomes unstable. Therefore, a compound which reacts with the acid such as an epoxy compound is preferable. In particular, compounds having an epoxy group and an ether bond such as diglycidyl ether compounds such as polyalkylene glycol diglycidyl ether, monoglycidyl ether compounds such as phenyl glycidyl ether, and aliphatic cyclic epoxy compounds are preferable. The reason is that the epoxy group of these compounds captures an acid, and contributes to the improvement of the compatibility between the refrigerating machine oil and the refrigerant even if the ether bond is more or less.

The above-mentioned other additives include a chlorine scavenger for eliminating the influence of residues such as a chlorine-based cleaning agent used in manufacturing a compressor and a refrigeration system, and an oxidizing agent during oil passage and storage. It is an additive for preventing deterioration, an additive for preventing foaming, and the like, which is at a level that can be handled by conventional general techniques, and is not specifically regulated here.

As extreme pressure additives, for example, primary and secondary OH groups remaining in molecules such as alkyl polyoxyalkylene phosphates and dialkyl phosphates can be used.
When a suitable amount of 0.05 to 10 wt% of high-grade strong phosphate ester is blended, the ester-bonded lubricating oil film that is molecularly oriented on the surface of the iron-based sliding portion that forms the shaft and bearing of the compressor is removed. Thus, a stronger phosphate ester chemical adsorption film can be formed, the lubricating properties of the sliding portion can be improved, and biting and seizure can be prevented.

[0022]

As described above, in the refrigerating apparatus and the compressor of the present invention, an ester oil or an ether oil is used as a base oil, and a part of glycerin is reacted with a fatty acid, and an esterified compound is added thereto. Thus, a chemical adsorption film is formed on the surface of the sliding portion, and it is possible to prevent the metal surface from directly contacting and causing seizure and abnormal wear. for that reason,
It is possible to provide a refrigerant compressor filled with a refrigerating machine oil having excellent wear resistance in the coexistence of a hydrofluorocarbon-based refrigerant which is a substitute for Freon 22, and to provide a highly reliable refrigerating apparatus equipped with the refrigerant compressor. can do.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a hermetic rotary compressor.

FIG. 2 is a diagram showing the relationship between the amount of additive and the amount of wear in a Falex wear test.

FIG. 3 is a configuration diagram of a refrigeration cycle of the refrigeration apparatus.

FIG. 4 is a graph showing a temperature characteristic of a two-layer separation between R410A and a refrigerator oil.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Case 2 Cylinder 3 Eccentric part 4 Rotating shaft 5 Main bearing 6 Sub bearing 7 Roller 8 Cylinder groove 9 Spring 10 Vane 11 Vertical hole 12 Rotor 13 Stator 14 Motor 15 Compressor part 16 Refrigeration oil 17 A part of glycerin with fatty acid Compound esterified by reaction 18 Compressor 19 Condenser 20 Expansion mechanism 21 Evaporator 22 Dryer

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kenichi Kawashima 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Ryo Ota 7-1 Omikamachi, Hitachi City, Ibaraki Prefecture No. 1 Inside the Hitachi Research Laboratory, Hitachi, Ltd.

Claims (8)

[Claims] 1. A refrigerant compressor used in a refrigeration cycle, comprising: a motor including a rotor and a stator in a closed container for storing refrigerating machine oil; a rotation shaft fitted to the rotor; In the refrigerant compressor containing a compressor unit connected to the motor via the above, the refrigerant to be filled is composed of at least one type of hydrofluorocarbon having a critical temperature of 40 ° C. or higher, and is used for the refrigerant compressor. Refrigerating machine oil is based on ester oil or ether oil,
A refrigerant compressor containing a compound obtained by reacting a part of glycerin with a fatty acid and esterifying it. 2. At least a compressor, a condenser, a dryer,
In a refrigerating apparatus including an expansion mechanism, an evaporator, and a refrigerant pipe connecting the same, a refrigerant compressor includes: a motor including a rotor and a stator in a closed container storing refrigerating machine oil; and a rotation mounted on the rotor. A shaft and a compressor section connected to the motor via the rotating shaft are housed therein.
At least one of a hydrofluorocarbon type at 0 ° C. or higher
Refrigeration oil used for refrigerant compressors,
A refrigerating apparatus containing a compound obtained by reacting a part of glycerin with a fatty acid and esterifying the ester oil or the ether oil as a base oil. 3. A refrigerant device having at least a refrigerant compressor, a condenser, a dryer, an expansion mechanism, and an evaporator and refrigerant piping connecting the refrigerant compressor, wherein the refrigerant compressor is provided in an airtight container storing refrigerant refrigerant oil. A motor consisting of a rotor and a stator, a rotating shaft that is in close contact with the rotor, and a compressor section connected to the motor via the rotating shaft are housed, and the refrigerant to be sealed is At least one of a hydrofluorocarbon type having a critical temperature of 40 ° C. or higher
Refrigeration oil used for refrigerant compressors,
A refrigeration apparatus containing an additive having a structure comprising a compound obtained by reacting a part of glycerin represented by the monoester of the general formula I or the diester of the general formula II with a fatty acid and esterifying the ester oil as a base oil. . Embedded image Embedded image 4. The refrigerating machine oil comprising an ester oil as a base oil, wherein said additive is added in an amount of 0.1 to 2.5%, preferably 0.1 to 0.8%. Refrigeration equipment. 5. A refrigerant device comprising at least a refrigerant compressor, a condenser, a dryer, an expansion mechanism, and an evaporator and a refrigerant pipe for connecting the refrigerant compressor, wherein the refrigerant compressor is provided in an airtight container for storing refrigerant oil. A motor consisting of a rotor and a stator, a rotating shaft that is in close contact with the rotor, and a compressor section connected to the motor via the rotating shaft are housed, and the refrigerant to be sealed is At least one of a hydrofluorocarbon type having a critical temperature of 40 ° C. or higher
Refrigeration oil used for refrigerant compressors,
A refrigeration apparatus containing an additive having a structure comprising a compound obtained by reacting a part of glycerin represented by a monoester of the general formula I or a diester of the general formula II with a fatty acid and esterifying the same with an ether oil as a base oil. . Embedded image Embedded image 6. The refrigerating machine according to claim 5, wherein said refrigerating machine oil containing ether oil as a base oil contains said additive in an amount of 0.1 to 3%, preferably 0.1 to 2%. 7. The refrigerating apparatus according to claim 3, wherein the fatty acid portion of the compound obtained by reacting a part of glycerin with a fatty acid and esterifying is oleic acid. 8. The refrigerating apparatus according to claim 3, wherein at least one of an acid scavenger, an antioxidant, an extreme pressure additive and an antifoaming agent is added to the refrigerating machine oil.