JPH04122792A - Refrigerator - Google Patents

Abstract

PURPOSE:To obtain a refrigerator wherein the moisture of a working medium is effectively removed and lower fatty acids are removed by adsorption so that the flaking of a roller bearing can be prevented by providing a specified acid adsorbent in the passage of a specified working medium or in an aliphatic synthetic lubricating oil. CONSTITUTION:In a refrigerator equipped with a refrigerating compressor using a mixture of a fluorohydrocarbon refrigerant [preferably one shown by the formula (wherein (x) is 1 to 3; (y) is 1 to 7; (z)is 1 to 7) and having a critical temperature of 40 deg.C or lower] and an aliphatic synthetic lubricating oil (e.g. a polyalkylene glycol or neopentyl polyol ester) as the working refrigerant, an acid adsorbent selected from an ion exchange resin (preferably a weakly basic anion exchange resin having an amino group as the exchange group) and an epoxy compound (e.g. phenyl glycidyl ether) is provided in the passage of the working medium or in the lubricating oil. This gives a refrigerator wherein the moisture in the medium is effectively removed and about 1-3C lower fatty acids are removed by adsorption so that the flaking of a roller bearing can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a refrigeration system, and particularly to a refrigeration system using a refrigeration compressor with roller bearings, such as a car air conditioner.

[Conventional technology]

In recent years, refrigeration systems such as car air conditioners have become smaller and more sophisticated, and refrigeration systems that automatically control the flow rate of refrigerant, which is the working medium of a refrigeration compressor, according to indoor temperature have appeared.

The above-mentioned refrigeration compressor is a single swash plate type having a piston on one side, and the refrigeration capacity can be adjusted by changing the inclination angle of this swash plate depending on the room temperature. On the other hand, since this swash plate is supported by bearings or has a large load, a roller bearing with a large load capacity is used as the bearing.

Dichlorodifluoromethane (CC
QxFx: R12) is used. Furthermore, naphthenic or paraffinic mineral oils are generally used as lubricating oils because they have good compatibility with refrigerants.

However, due to the environmental problem that R12 destroys the earth's ozone layer, its use has been regulated, and an alternative is required.

What refrigerants can be considered as an alternative to R12?

A hydrofluorocarbon or fluorocarbon that has a boiling point close to that of R12 and is currently being considered for practical use as an alternative refrigerant is 1,1°1,2-tetrafluoroethane (CFsCHFz; R134a).

However, this refrigerant has a drawback of extremely poor compatibility with general mineral oil-based lubricating oils. [Frozen 60816 (19
1985)]. The reason for this is thought to be that it does not have chlorine in its molecule like R12 [Asure Guide and Data Book (^5RAE Guide and Data Book)]
Data Book) page 307 (1969)).

[Problem to be solved by the invention]

Polyalkylene glycol has been proposed as a lubricating oil that dissolves in the hydrofluorocarbon (R134a) (US Pat. No. 4,755,316).

However, this polyalkylene glycol has a problem in that it is highly hygroscopic. When a refrigeration compressor is operated using a lubricating oil with a high water content, flaking (a phenomenon in which an area of a certain size or larger is corroded and peeled off) occurs on the roller bearing surface due to fatigue, which may cause the compressor to become inoperable. may fall into.

In order to prevent this flaking, it is possible to use polyalkylene glycol from which moisture has been removed from the oil, but in the case of car air conditioners, it is not easy to prevent moisture from penetrating through the rubber hoses of the piping.

FIG. 1 is a sectional view showing an example of a swash plate type refrigeration compressor for a car air conditioner.

The refrigeration compressor is driven by transmitting the rotational force of the engine to the pulley 1 via a V-belt (not shown). The compressor is operated and stopped by applying or disconnecting current to the coil 2 of the magnetic clutch, thereby engaging or disengaging the clutch.

When the magnetic clutch is engaged, a swash plate 6 attached to the shaft 3 rotates, and a piston 8 moves left and right via a connecting rod 7. This reciprocating movement of the piston 8 introduces low-pressure refrigerant gas into the cylinder, compresses it into high-pressure refrigerant gas, and adiabatically expands the high-pressure refrigerant gas with an expansion valve to generate cold heat. Compressor swash plate 6 and piston support 9
A roller bearing 5 is inserted between the swash plate 6 and a roller bearing 4 to support the reaction force of the piston applied to the swash plate 6.

The roller bearing 4.5 is lubricated by supplying a working medium consisting of a mixture of refrigerant and lubricating oil present at the bottom of the front cover 10, which is splashed by the rotational movement of the swash plate, thereby reducing bearing friction and burning out. To prevent sticking.

At this time, when a refrigeration compressor is operated using a lubricating oil such as polyalkylene gellicol with a high moisture content, flaking occurs on the roller bearing surface. This flaking is thought to be caused by brittle fracture caused by hydrogen generated by decomposition of water.

Furthermore, since this flaking occurs relatively easily, we investigated other acceleration factors such as moisture and found that lower fatty acids, which are hydrolyzed products of lubricating oil, are involved [Wear voQ 24 (1974)] 107-11
8].

In other words, polyalkylene gelylcols (especially those with ester groups) and neopentyl polyesters, which have a high water content, are heated to about 100°C in a refrigeration compressor to form lower grades of about 01 to Ca. It is thought that fatty acids are produced, which corrode the microclutches formed on the roller bearing surface, and are decomposed by the chemically active microclutches to produce hydrogen, which accelerates flaking.

In this case as well, hydrolysis occurs due to moisture in the oil, and it is most desirable to reduce the moisture in the oil to suppress the occurrence of flaking, but it is possible to suppress flaking by adsorbing and removing lower fatty acids. .

The purpose of the present invention is to effectively remove moisture from the medium and to
The object of the present invention is to provide a refrigerant device that suppresses flaking of roller bearings by adsorbing and removing lower fatty acids of about C3.

[Means to solve the problem]

The gist of the present invention for achieving the above object is as follows.

(1) In a refrigeration system equipped with a refrigeration compressor that uses a fluorinated hydrocarbon refrigerant and an aliphatic synthetic lubricant as a working medium, an ion exchange resin or an epoxy compound is used in the flow path of the working medium or in the lubricant. A refrigeration device characterized by being equipped with a selected acid adsorbent.

(2) As the fluorinated hydrocarbon refrigerant, general 2Cx
Hy F z ' [I ) (
However, X is an integer of 1 to 3, y is an integer of 1 to 7.2 is an integer of 1 to 7), and is selected from refrigerants whose critical temperature is 40 ° C.
A refrigeration system characterized in that at least one type of the above is used, and the aliphatic synthetic lubricating oil uses a working medium selected from polyalkylene glycol and neopentyl polyol ester.

(3) The ion exchange resin is a weakly basic anion exchange resin having an amino group as an exchange group, and the epoxy compound has acid adsorption properties such as phenyl or alkylphenyl glycidyl ether and a condensate of epichlorohydrin and bisphenol. A refrigeration device characterized by being a compound containing

In addition, for example, 1°1.
1.2-tetrafluoroethane (CFllCHF2HF
C134a), 1.1.2.2-tetrafluoroethane (CHF 2CHF x HFC134) and other refrigerants that do not contain chlorine in their molecules are used.

Further, the aliphatic synthetic lubricating oil is selected from at least one of polyalkylene glycol, neopentyl polyol ester, and polyether-modified siloxane. For example, polyalkylene gellicol is Nilasan Uniloop MB-11 (NOF), neopentyl polyol ester is NIRASAN UNISTA H3O8B (NOF), or polyether-modified silicone is PS555.
(manufactured by Chisso) etc.

The ion exchange resin that is an acid adsorbent is a weakly basic anion exchange resin that uses an amino group as an exchange group, such as Diaion WA30 (manufactured by Mitsubishi Kasei), Amberlyst A-21 (
(Made by Organo).

The object of the present invention can be achieved by placing the acid adsorbent as it is in a container provided in the flow path of the working medium of the refrigeration device and adsorbing and removing the lower fatty acids in the working medium. In addition, especially when a container or the like is not provided, it may be loaded together with the water-saving agent into the liquid tank 14 of the refrigeration system as shown in FIG. In that case, it is convenient and convenient to load it in a cloth bag.

That is, as shown in FIG. 2, the refrigerant compressed by the compressor 12 is transferred to the condenser 13. Liquid tank 14. Expansion valve 15. The liquid is transferred to the evaporator 16 and then to the refrigeration cycle, where it takes part in the refrigeration work, and it is effective to capture the lower fatty acids in the working medium in the liquid tank 14.

This acid adsorbent can be used for 1 kg of fluorinated hydrocarbon refrigerant and 2 kg of lubricating oil.
It is preferable to mix 40 tons or more per 00g.

In addition, epoxy compounds include Adekal Resin (manufactured by Kadenka)
There is an Epicoat range (manufactured by Shell Chemical). Incidentally, these epoxy compounds have been proposed as additives to capture chlorine compounds, which are the reaction products of conventional refrigerants containing chlorine in their molecules and lubricating oils [Japanese Patent Application Laid-open No. 1404-1989].
No. 69, Publication No. 59-91198].

It should be noted that an antifoaming agent, an extreme pressure agent for improving lubrication properties, etc. may be added to the working medium as long as it does not impede the purpose of the present invention.

[Effect]

The present invention can suppress flaking of roller bearings by adsorbing and removing lower fatty acids of about C1 to 03 from the hydrolyzate of lubricating oil, which is one of the working media. This is thought to be due to hydrogen penetration generated by highly active microcracks on the bearing surface caused by loading (fatigue), and the subsequent brittleness that does not occur.

That is, by suppressing the generation of hydrogen, microcracks are immediately joined and do not expand.

〔Example〕

Next, the present invention will be specifically explained using examples.

The hydrolyzability of polyalkylene glycol and neopentyl polyol ester having a viscosity of 50 to 60 cSt at 40° C. was compared depending on the presence or absence of acidification of the ion exchange resin or epoxy compound.

The hydrolyzability test was conducted as follows.

Pour 2mQ of lubricating oil into a glass container with an inner diameter of 7mo, a thickness of inn, and a length of 180I.
Insert 0m+ iron wire and copper wire, and seal the upper end with a gas burner.

This glass container is placed in a metal protection tube and heated in a high temperature heating tank at 150°C. After heating for 24 hours, the tube was opened, the lubricating oil was taken out, and its total acid value was measured, and the degree of discoloration of the iron wire and copper wire (especially the transfer of copper to the iron wire) was measured.

In other words, the presence or absence of copper plating phenomenon) is observed. The total acid value is
It is expressed in mg of KOH that neutralizes 1 g of lubricating oil, and its measurement is performed by the petroleum product neutralization value testing method specified in JIS K2501.

Furthermore, the fatigue life of roller bearings was measured when an ion exchange resin or an epoxy compound was present in the mixture of lubricating oil and refrigerant.

The lubricating oil at this time was polyalkylene glycol with high hygroscopicity (Ssan Uniloop MB-11).

The refrigerant is 1,1,1,2-tetrafluoroethane (HFC
134a), and the initial moisture content of the mixed liquid is approximately -10,000 ppm.
It is.

A fatigue life test for roller bearings was conducted as follows.

A high-pressure atmosphere friction tester with a mechanical seal installed between the rotating shaft and the test container was used as the tester. A thrust needle bearing (basic dynamic load rating of 1,680 kgf) with an inner diameter of 30 kgf was inserted into the test container, and lubricating oil was filled so that the bearing was immersed in the test container. After evacuation, 2 kgf was placed in the container.
/adG 1.1,1°2-tetrafluoroethane is introduced. Run for 30 minutes with no load.

Next, add a load equal to the basic dynamic load rating of the bearing,
Start operation at 2,000 rpm. During operation, the value of a vibration detector (NSK bearing monitor) attached to the side of the container is monitored, and when the value increases due to the occurrence of flaking, the operation is stopped and the previous time (1) and the next time are monitored. Formula (1
) to (3), the rated fatigue life of the test bearing (
Find the ratio to L).

L = 500 x f h 10/”
...(1) f h=f nXCa/P
"42) f n = (3,33/n)"
-(3) Here, L: Roller bearing fatigue life (h) Ca: Basic dynamic load rating (kg f) p: Test load (kg f) n: Number of rotations (rpm) At this time, ensure that there is sufficient lubrication. For example, the ratio to this fatigue life t/
L is 1 or more. If it is lower than 1, it indicates a lubrication defect.

Table 1 shows the total acid value of Examples and Comparative Examples after heating at 150°C for 24 hours, presence or absence of copper plating phenomenon, and Table 2 shows the ratio to fatigue life (t/L) representing flaking life of roller bearings. showed that.

As is clear from Table 1, the total acid values of the lubricating oils shown in Examples 1 to 7 in which ion exchange resins or epoxy compounds coexisted were low, and they effectively adsorbed lower fatty acids, which are hydrolyzed products of lubricating oils. Or it shows that they are reacting.

Moreover, the effect of suppressing the copper plating phenomenon is also recognized.

Furthermore, as is clear from Table 2, the ratio (t/L) to fatigue life is low in the comparative example that does not contain an acid adsorbent. This seems to be due to the influence of lower fatty acids due to hydrolysis. On the other hand, the ratio to fatigue life of the example in which the epoxy compound was blended was t/L=1.0, and the effect of blending the acid adsorbent was recognized.

In this embodiment, a car air conditioner has been described, but the present invention can also be applied to general air conditioners and refrigeration devices such as refrigerators.

〔Effect of the invention〕

The present invention has the effect of suppressing the copper plating phenomenon and flaking on the bearing surface of a refrigeration compressor, and can extend the life of air conditioners and refrigerators.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a swash plate compressor for a car air conditioner according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a refrigeration cycle for a car air conditioner according to the present invention. 1...Pulley, 2...Coil, 3...Shaft,
4, 5... Roller bearing, 6... Swash plate, 7... Connecting rod, 8... Piston, 9... Piston support, 1o. Front cover, 11... Acid adsorbent,
12... Compressor, 13... Condenser, 14... Liquid tank, 15 - Expansion valve, 16... Evaporator, 17... Blower, 18... Radiator, ? Coil 3-°Shaft 4゛ Roller candy 1 bearing 5 ・25 bearing 6-Rate 7- Konekunan 20. G8・Hi0ston 9 Piston S.R.T10' To front force - 1st

Claims (1)

[Scope of Claims] 1. In a refrigeration system equipped with a refrigeration compressor using a fluorinated hydrocarbon refrigerant and an aliphatic synthetic lubricant as working refrigerants, in the flow path of the working medium or in the aliphatic synthetic lubricant. A refrigeration device characterized in that an acid adsorbent selected from an ion exchange resin or an epoxy compound is arranged on the refrigeration system. 2. The fluorinated hydrocarbon refrigerant has the general formula [I]C_x
H_yF_z [ I ] (However, x is an integer from 1 to 3, y is from 1 to 7, and z is an integer from 1 to 7)
, the critical temperature is 40°C or less, the aliphatic synthetic lubricant is polyalkylene glycol,
The refrigeration system according to claim 1, wherein the working medium is selected from neopentyl polyol ester. 3. The ion exchange resin is a weakly basic anion exchange resin having an amino group as an exchange group, and the epoxy compound is a compound having acid adsorption properties such as phenyl or alkylphenyl glycidyl ether and a condensate of epichlorohydrin and bisphenol. The refrigeration apparatus according to claim 1 or 2.