JP2507160B2 - Refrigeration equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a refrigerating apparatus, and more particularly to a refrigerating apparatus using a refrigerating compressor having a roller bearing such as a car air conditioner.

[Conventional technology]

2. Description of the Related Art In recent years, refrigeration systems such as car air conditioners have become smaller and have higher performance, and a refrigeration system of a type that automatically controls the flow rate of a refrigerant, which is a working medium of a refrigeration compressor, according to an indoor temperature has appeared.

The refrigeration compressor described above is a swash plate type having a piston on one side, and the refrigerating capacity can be adjusted by changing the inclination angle of the swash plate depending on the room temperature. On the other hand, this swash plate is supported by bearings, but its load is large, so
A roller bearing with a large load capacity is used as the bearing.

Dichlorodifluoromethane (CCl ₂
F ₂ ; R12) is used. Further, as the lubricating oil, naphthene-based or paraffin-based mineral oil is generally used because it has good compatibility with the refrigerant.

However, due to the environmental problem of depleting the ozone layer of the earth, the use of R12 is regulated, and a substitute for this is required.

Possible alternatives to R12 are hydrofluorocarbons or fluorocarbons, which have similar boiling points to R12. At present, 1,1,1,2-tetrafluoroethane (CF ₃ CH
F ₂ ; R134a) is available.

However, this refrigerant has a drawback that its compatibility with general mineral oil-based lubricating oil is extremely poor. [Frozen 60816 (1985
Year)〕. The reason is considered to be that there is no chlorine in the molecule like R12 [ASRAE Guide and Data Book] p. 307 (19
69)].

[Problems to be Solved by the Invention]

As a lubricating oil that dissolves in the hydrofluorocarbon (R134a), polyalkylene glycol has been proposed (US Pat. No. 4,755,316). However, this polyalkylene glycol has a problem that it has high hygroscopicity. When a refrigeration compressor is operated using a lubricating oil with a high water content in the oil, flaking due to fatigue (a phenomenon in which an area of a certain size or larger is corroded and peeled off) occurs on the roller bearing surface. You may be unable to drive.

In order to prevent this flaking, it is conceivable to use polyalkylene glycol from which water in oil has been removed, but in the case of a car air conditioner, it is not easy to prevent water that permeates from the rubber hose of piping.

FIG. 1 is a sectional view showing an example of a swash plate type refrigeration compressor of 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 connecting or disconnecting the clutch by turning on or off the current to the coil 2 of the magnet clutch.

The swash plate 6 attached to the shaft 3 rotates due to the coupling of the magnet clutch, and the piston 8 moves left and right via the connectin rod 7. By the reciprocating operation of the piston 8, a low-pressure refrigerant gas is introduced into the cylinder and compressed into a high-pressure refrigerant gas, and the high-pressure refrigerant gas is liquefied by a condenser,
The high pressure refrigerant is adiabatically expanded by an expansion valve to obtain a cold heat source. The roller bearing 5 is provided between the swash plate 6 and the piston support 9 of the compressor.
Is inserted, and in order to support the reaction force of the piston applied to the swash plate 6, the roller bearing 4 is inserted.

Lubrication of the roller bearings 4 and 5 is performed by splashing and supplying a working medium composed of a mixture of refrigerant and lubricating oil existing at the bottom of the front cover 10 by the rotational movement of the swash plate to reduce the friction of the bearings. To prevent seizure.

At this time, it has been experienced that flaking occurs on the surface of the roller bearing when the refrigeration compressor is operated using a lubricating oil such as polyalkylene glycol having a high water content.
This flaking is considered to be caused by brittle fracture due to hydrogen generated by decomposition of water.

Furthermore, since this flaking occurs relatively easily, an investigation of other accelerating factors for water content revealed that lower fatty acids, which are hydrolysates of lubricating oil, are involved [Wear vol24 (1974) 107- 118].

That is, polyalkylene glycol with a high water content (especially those having an ester group among them) and neopentylpolyester are heated to about 100 ° C in a refrigerating compressor, so that C _{1 to} C ₃ It is considered that lower fatty acids are produced, which corrode the microcracks generated on the roller bearing surface and decompose by chemically active microcracks to produce hydrogen, which accelerates flaking.

In this case as well, hydrolysis is caused by water in the oil, and it is most desirable to reduce the water in the oil in order to suppress the occurrence of flaking, but it is also possible to suppress flaking by capturing and removing lower fatty acids. it can.

An object of the present invention is to effectively remove moisture of the medium, C ₁ ~
An object of the present invention is to provide a refrigerant device which suppresses flaking of roller bearings by capturing and removing lower fatty acids of about C ₃ .

[Means for solving the problem]

The present invention, in order to achieve the above object, in a refrigerating apparatus provided with a refrigeration compressor using a fluorohydrocarbon refrigerant and an aliphatic synthetic lubricating oil as a working medium, epichlorohydrin and bisphenol in the flow path of the working medium. An acid scavenger container containing a condensate of the above is arranged.

Here, the fluorohydrocarbon-based refrigerant is, for example, a general formula CxHyFz [I] (where x is 1 to 3, y is 1 to 7, and z is an integer of 1 to 7).
, Selected from refrigerants having a critical temperature of 40 ° C. or higher,
At least one of them. For example, 1,1,1,2-tetrafluoroethane (CF ₃ CHF ₂ HFC134a), 1,1,2,2-tetrafluoroethane (CHF ₂ CHF ₂ HFC134) such as chlorine-free refrigerant is used. To be

The aliphatic synthetic lubricating oil is selected from, for example, at least one of polyalkylene glycol and neopentyl polyol ester. For example, polyalkylene glycol is Nissan Uniloop MB-11 (manufactured by NOF Corporation), neopentylpolyol ester is Nissan
There is Unistar H308B (made by NOF Corporation).

The object of the present invention can be achieved by placing the acid scavenger as it is in a container (housing) provided in the flow path of the working medium of the refrigerating apparatus to trap and remove the lower fatty acid in the working medium. . Further, when the container or the like is not provided, as shown in FIG. 2, it may be loaded in the liquid tank 14 of the refrigerating apparatus in the coexistence with the water-saving agent. In that case, it is convenient to put it in a cloth bag (housing) and load it.

That is, as shown in FIG. 2, the refrigerant compressed by the compressor 12 is successively carried to the condenser 13, the liquid tank 14, the expansion valve 15, and the evaporator 16 in the refrigeration cycle to participate in the refrigeration work. However, it is effective to capture the lower fatty acid in the working medium in the liquid tank 14.

This acid scavenger is a fluorocarbon refrigerant 1 kg lubricating oil 200
It is recommended to add more than 40g per g Further, the condensate of epichlorohydrin, which is an acid scavenger, and bisphenol includes Epicoat Range (produced by Ciel Chemical Co., Ltd.). Here, the lower fatty acid scavenging reaction according to the present invention is represented as follows.

Incidentally, the object of the present invention, as long as it does not hinder,
An antifoaming agent or an extreme pressure agent for improving lubrication characteristics may be added to the working medium.

[Action]

According to the above configuration, flaking of the roller bearing can be suppressed even when the fluorinated hydrocarbon refrigerant contains the aliphatic synthetic lubricating oil. That is, a lower fatty acid of about C _{1 to} C ₃ of a hydrolyzate of lubricating oil which is one of working fluids is captured by a condensate of epichlorohydrin and bisphenol,
Repeated load (fatigue) on the roller bearing due to removal
This is due to the infiltration of hydrogen generated by the highly active microcracks on the bearing surface, which is not caused by subsequent brittleness.

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

〔Example〕

 Next, the present invention will be specifically described with reference to examples.

The hydrolyzability of polyalkylene glycol and neopentylpolyol ester having a viscosity at 40 ° C. of 50 to 60 cSt was compared with and without an ion exchange resin and an epoxy compound. In addition, what corresponds to the Example of this invention is a condensate of epichlorohydrin and bisphenol among epoxy compounds (Epicoat 828 described in Example 5 of Table 1 corresponds to this).

 The hydrolyzability test was conducted as follows.

2 ml of lubricating oil is poured into a glass container having an inner diameter of 7 mm, a thickness of 1 mm and a length of 180 mm, and an iron wire and a copper wire having a diameter of 1.6 mm and a length of 40 mm are put into the glass container, and the upper end is sealed 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, open the tube to take out the lubricating oil, measure the total acid value, and observe the degree of discoloration of the iron wire and the copper wire (especially the transfer of copper to the iron wire, that is, the presence or absence of the copper plating phenomenon). The total acid value is expressed in mg of KOH that neutralizes 1 g of lubricating oil, and the measurement is performed by the petroleum product neutralization value test method specified in JIS K2501.

Further, the fatigue life of the roller bearing when the ion exchange resin or the epoxy compound was made to coexist in the mixture of the lubricating oil and the refrigerant was measured.

At this time, the lubricating oil is a highly hygroscopic polyalkylene glycol (Nissan Uniloop MB-11), the refrigerant is 1,1,1,
It is 2-tetrafluoroethane (HFC134a), and the initial water content of the mixed solution is about 10,000 PPm.

 The fatigue life test of the roller bearing was performed as follows.

A high-pressure atmosphere friction tester provided with a mechanical seal between the rotary shaft and the test container was used as the tester. Insert a thrust needle bearing with an inner diameter of 30 mm (basic dynamic load rating 1680 kgf) into the test container, fill it with lubricating oil so that the roller bearings are submerged, and evacuate the chamber to 2 kgf / cm ² G 1,1, 1,2
-Introduce tetrafluoroethane. 30 with no load
Run for a minute.

Then, a load equal to the basic dynamic load rating of the bearing is applied and operation is started at 2,000 rpm. During operation, the value of the vibration detector (bearing monitor made by NSK) attached to the side of the container is monitored, and when the value increases due to flaking, the operation is stopped. The ratio to the rated fatigue life (L) of the test bearing is calculated by the equations (1) to (3).

L = 500 × fh ^10/3 (1) fh = fn × Ca / p (2) fn = (3.33 / n) ^3/10 (3) where L: Fatigue life of roller bearing (h) CA: Basic operating load rating (kg f) p: Test load (kg f) n: Rotation speed (rpm) At this time, if lubrication is sufficient, the ratio to this fatigue life t /
L is 1 or more. If it is lower than 1, it indicates that there is a defect in lubrication.

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

As is clear from Table 1, the total acid value of the lubricating oil in which the ion exchange resin or the epoxy compound shown in Examples 1 to 7 coexist is low, and the lower fatty acid which is a hydrolyzate of the lubricating oil is effectively Indicates that it is trapping or reacting. Also, the effect of suppressing the copper plating phenomenon is recognized.

Further, as is clear from Table 2, the ratio (t / L) to the fatigue life is low in the comparative example containing no acid scavenger. This seems to be the effect of lower fatty acids due to hydrolysis. On the other hand, the ratio to the fatigue life of the example in which the epoxy compound was blended was t / L = 1.0, which shows the effect of blending the acid scavenger.

Although a car air conditioner has been described in this embodiment, the present invention can be applied to a refrigerating device such as a general air conditioner and a refrigerator.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY 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 description of drawings]

FIG. 1 is a vertical sectional view of a swash plate type 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 of the car air conditioner of the present invention. 1 ... Pulley, 2 ... Coil, 3 ... Shaft, 4,5 ...
… Roller bearings, 6 …… swash plate, 7 …… Connectin glove,
8 ... Piston, 9 ... Piston support, 10 ... Front cover, 11 ... Acid adsorbent, 12 ... Compressor, 13 ... Condenser, 14 ... Liquid tank, 15 ... Expansion valve, 16 ... …Evaporator,
17 …… Blower, 18 …… Radiator, 19 …… Refrigerant piping.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location C10N 30:12 C10N 40:30 40:30 F04B 27/08 Q (72) Inventor Yutaka Ito Ibaraki Prefecture Hitachi, Ltd. 4026 Kuji Town, Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Shigeki Komatsuzaki 4026 Kuji Town, Hitachi City Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi Ltd. (72) Atsushi Kishi Katsuda City, Ibaraki 2520 Takaba Address: Hitachi, Ltd., Sawa Plant (72) Inventor, Toru Iizuka, 800, Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Prefecture, Hitachi Ltd., Tochigi Plant (56) Reference JP-A-3-275799 (JP, A) Kaihei 4-55498 (JP, A)

Claims (1)

(57) [Claims] 1. A refrigeration apparatus equipped with a refrigeration compressor using a fluorohydrocarbon refrigerant and an aliphatic synthetic lubricating oil as a working medium, wherein an acid composed of a condensate of epichlorohydrin and bisphenol is provided in a flow path of the working medium. A refrigerating apparatus having a storage body for a scavenger.