JPH0791535B2 - Working medium for refrigerator and refrigerating apparatus using the medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a working medium for a refrigerator, and more particularly, to a refrigerating compressor having a roller bearing in a rotary drive unit of a car air conditioner, a room air conditioner, a package air conditioner, a refrigerator, or the like. The present invention relates to a working medium of a machine and a refrigerating apparatus using the working medium.

[Prior Art] In recent years, proper cooling and heating and low noise have been aimed at in order to improve indoor habitability of automobiles, etc., and in addition to miniaturization and high performance of refrigerators, the flow rate of the refrigerant, which is the working medium of the refrigeration compressor, can be controlled by the indoor temperature. Automatically controlled refrigerators have appeared.

The refrigerating compressor is a swash plate type having a piston on one side as shown in FIG. 1, and the refrigerating capacity can be controlled by arbitrarily changing the inclination angle of the swash plate depending on the room temperature. The differential plate is supported by a bearing, but its load is large. Therefore, a roller bearing having a large load capacity is used for the rotation driving unit of the bearing.

Also, in car air conditioners, room air conditioners and package air conditioners, energy saving, low noise, optimum cooling and heating are aimed, and from the aspects of compressor efficiency improvement, low torque fluctuation, speed control with inverter, etc. Scroll compressors such as those shown in Figure 2 are becoming mainstream.

In this compressor, two spiral wraps 12, 12 'having substantially the same shape are opposed to each other and meshed with each other, and one lap is swung by a crankshaft connected to the other wrap. The refrigerant is sucked and compressed.

In this compressor, the reaction force of the compression torque is supported by the bearing, but since the load is large, a cylindrical roller bearing having a large load capacity is adopted as the bearing.

Dichlorodifluoromethane (CCl ₂₎ , a type of halogenated hydrocarbon, is used as a refrigerant for the working medium of refrigerators such as car air conditioners, room air conditioners, and package air conditioners.
F ₂ ; R12) and monochlorodifluoromethane (CHClF ₂ ; R22)
Is used.

Further, as the lubricating oil, naphthene-based or paraffin-based mineral oil is widely used because of its good compatibility with the refrigerant.

However, due to the environmental problem of depleting the ozone layer of the earth, the use of R12 and R22 is restricted,
Alternatives to this are required.

Possible such refrigerants are those having boiling points close to the respective boiling points of the above refrigerants, such as hydrofluorocarbons or fluorocarbons.

Currently, those which practically have been considered as an alternative refrigerant R12, 1,1,1,2-tetrafluoroethane (CF ₃ HC
F ₂ ; R134a) and as an alternative refrigerant to R22, difluoromethane (CH ₂ F ₂ ; R32) and the above R134a alone, or the above R134a, R32, pentafluoroethane (CHF ₂ CF ₃ ; R125,
1,1,2,2-tetrafluoroethane (CHF ₂ CHF ₂ ; R134), 1,
1,1-trifluoroethane (CF ₃ CH _3; R143a) mixed mixed refrigerant include two such.

However, this refrigerant has the drawback of being extremely incompatible with general mineral oil-based lubricating oils [refrigeration 60 816 (1985
Year)〕. The reason for this is thought to be that there is no chlorine in the molecule like R12 and R22 [Assure Guide
And Data Book (ASRAE Guide and Data B
ook) p. 307 (1969)].

[Problems to be Solved by the Invention] Polyalkylene glycols (US Pat. No. 4,755,316) and polyol esters have been proposed as lubricating oils that dissolve in the hydrofluorocarbons and fluorocarbons.

However, these have a problem that they have a higher hygroscopicity than mineral oil-based lubricating oils, and when a refrigeration compressor is operated using such a lubricating oil with a high water content, flaking due to fatigue (relatively (Phenomenon in which a large area peels off and falls off) occurs, which may result in operation failure. In addition to this, when the water content in the oil is high, copper ions are deposited from the copper member used in the equipment that constitutes the refrigeration cycle and combine with an iron-based member such as a bearing to cause a so-called copper plating phenomenon, It causes seizure.

In order to prevent this flaking, a polyalkylene glycol in which the water content in the oil is removed to 200 ppm or less is proposed (JP-A-1
-198694). However, polyalkylene glycol and polyol ester are not easily dehydrated because they have a property of easily containing water.

Further, as a phenomenon peculiar to a car air conditioner, it is extremely difficult to prevent absorption of water that permeates from a seal portion using a rubber material such as a rubber hose for piping, an O-ring or a shaft seal. Therefore, in reality, it is unavoidable to use it with a certain amount of water content.

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 or stopped by connecting or disconnecting the current to or from the coil 2 of the magnet clutch to connect or disconnect the clutch.

Swash plate 6 attached to shaft 3 by coupling clutch
By rotating the, the piston is moved left and right via the connecting rod 7. By the reciprocating motion of the piston 8, the refrigerant gas in the cylinder is compressed into a high-pressure refrigerant gas, which is converted into a high-pressure liquid in a condenser provided outside the compressor, and the expansion valve performs oblique heat expansion to cool the refrigerant. You get the source.

A radial needle roller bearing 5 is mounted between the swash plate 6 and the piston support 9 of the compressor, and in order to support the reaction force of the piston applied to the swash plate 6, the radial needle roller bearing 4 is installed. It is installed.

Lubrication of the roller bearings 4 and 5 is performed by supplying a working medium, which is a mixture of a refrigerant and a lubricating oil retained at the bottom of the front cover 10, by splashing by the rotational movement of a swash plate to reduce friction and seizure of the bearing. We are trying to prevent it.

At this time, when the refrigeration compressor is operated using a lubricating oil having a high water content, such as poialkylene glycol, corrosion occurs in the microcrack portion generated on the surface of the roller bearing, and the expansion of microcracks due to this corrosion occurs. I am experiencing flaking. This flaking is considered to be due to brittle fracture due to hydrogen generated along with the corrosion of the bearing material.

Also, in the case of mineral oil type lubricating oil, the water content in the oil is 25, 10
As the amount increases to 0 and 400 ppm, the time until flaking occurs becomes shorter. For example, if 100ppm of water is 1, 400ppm
Has been reported to be 0.52 [ASLE Trans.20
(1977) 244].

As described above, the water content in oil is greatly involved in the occurrence of flaking. Therefore, it is most desirable to reduce the water content in the oil in order to suppress the occurrence of flaking, but it is very difficult to remove the water absorption when a lubricating oil having a high hygroscopic property such as polyalkylene glycol is used. Is.

In view of the above situation, an object of the present invention is to provide a working medium for a refrigerator in which flaking of a roller bearing due to water in lubricating oil is suppressed, and a refrigerator using the medium.

[Means for Solving the Problems] The gist of the present invention for achieving the above object is as follows.

(1) (a) Fluorohydrocarbon refrigerant, (b) Aliphatic synthetic lubricating oil, (c) General formula [I] and [II] (Wherein R ¹ is a cyclohexyl group, an isopropyl group, and R ² is an octyl group), and at least one of dialkylammonium nitrite and dialkylamine salt is contained in an amount of 0.01% by weight or more based on the lubricating oil. Working medium for refrigerators.

(2) (a) Fluorohydrocarbon refrigerant, (b) Synthetic lubricating oil comprising at least one of polyalkylene glycol, neopentyl polyol ester and polyether modified siloxane, (c) General formulas [I] and [II] [Wherein R ¹ is a cyclohexyl group, an isopropyl group, and R ² is an octyl group], and at least one of dialkylammonium nitrite and dialkylamine salt is contained in an amount of 0.01% by weight or more based on the lubricating oil. Working medium for refrigerators.

The fluorohydrocarbon refrigerant is represented by the general formula [III] CxHyFz [III] (where x is 1 to 3, y is 1 to 7 and z is an integer of 1 to 7).
, And at least one selected from refrigerants having a seaside temperature of 40 ° C. or higher is used. For example, 1,1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane or the like is used as a refrigerant containing no chlorine in the molecule.

Examples of the dialkylammonium nitrite represented by the general formula [I] include dicyclohexyl nitrite (VPI powder manufactured by Showa Shell Sekiyu KK), diisopropyl nitrite, or a mixture thereof with the above (Ranran manufactured by Johoku Chemical Co., Ltd.). There is a rust preventive agent.

Examples of the dialkylamine salt represented by the general formula [II] include dicyclohexylamine octate represented by the formula [IV] (VARDEN-10 manufactured by Nippon Ferroguard Co., Ltd.).
0E) etc.

As the lubricating oil, for example, Nissan Unilube MB-11 (manufactured by NOF Corporation) as polyalkylene glycol, Nissan Unistar H308B (manufactured by NOF Corporation, ester of trimethylolpropane) as neopentyl oriol ester, or polyether modified Examples of siloxanes include PS555 (made by Chisso).

The amount of the dialkylammonium nitrite or the dialkylamine salt to be added is 0.01% by weight or more based on the lubricating oil, because if it is less than 0.01% by weight, the effect of suppressing flaking cannot be sufficiently obtained. Depending on the coexistence of a refrigerant or the type of lubricating oil, the aliphatic salt is precipitated,
Since there is a concern that the nozzle of the expansion valve of the refrigerator may be clogged, it is preferably 5% by weight or less.

It should be noted that an antifoaming agent, an extreme pressure agent for improving lubrication characteristics, or the like may be added to the working medium as long as the object of the present invention is not impaired.

[Function] The dialkylammonium nitrite and dialkylamine salt added to the lubricating oil are vaporized in a closed atmosphere containing iron preparation members and the like to form a rust-proof film on the surface of the steel material. This is a rust preventive agent that prevents steel from rusting.

In the present invention, the reason why the dialkylammonium nitrite and the dialkylamine salt suppress flaking of the roller bearing is considered to suppress water, which is a source of generation of hydrogen, which is a cause. That is, the aliphatic salt added to the working medium penetrates into a very active microcrack portion of the bearing surface generated by the repeated load (fatigue) of the roller bearing,
It is considered that hydrogen is prevented from being generated because it is adsorbed on the surface and blocks moisture, so that expansion of microcracks can be suppressed and flaking can be suppressed.
If hydrogen evolution does not occur, the microcracks will join immediately and will not propagate.

[Examples] Next, the present invention will be specifically described with reference to Examples.

The fatigue life of roller bearings was compared for polyalkylene glycol, neopentyl polyol ester, and polyether-modified siloxane having a viscosity at 40 ° C. of 50-60 cSt with and without the presence of the dialkylammonium nitrite and dialkylamine salts.

A 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. A thrust needle bearing (basic copper rated load 1680 kgf) having an inner diameter of 30 mm was mounted in the test container, and the lubricating oil was filled so that the bearing was immersed. After evacuation of this, 2 kgf / cm ² in the container
G 1,1,1,2-tetrafluoroethane was introduced. This is conditioned for 30 minutes at 1000 rpm with no load.

Next, apply a load equal to the basic same rated load of the bearing,
Start operation at 2000 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 significantly due to flaking, the operation is stopped and the operation time until then (t) And the rated fatigue life (L) of the test bearing calculated by the following equations (1) to (3).

L = 500 ・ fh ^10/3 …… (1) fh ＝ fn ・ Ca / p …… (2) fn = (3.33 / n) ^3/10 …… (3) However, L: Fatigue life time of roller bearing (H) Ca: Basic same rated load (kgf) p: Bearing load (kgf) n: Rotation speed (rpm) At this time, if lubrication is sufficient, the ratio (t / L) to this rated fatigue life is 1 or more. Becomes If lower than 1,
It shows that the lubricity is defective.

Tables 1 to 4 show t / L values of Examples and Comparative Examples.

As is clear from Table 1, in the case of the compounded oil of the dialkylammonium nitrite and dialkylamine salt shown in Examples 1 to 6, the ratio to the rated fatigue life was 0.9 when the content of the salt was 0.01% by weight or more. As described above, the effect of suppressing flaking based on the water content in oil is recognized.

On the other hand, t / L of Comparative Examples 1 to 3 in which the dialkylammonium nitrite and the dialkylamine salt are not mixed is 0.3
~ 0.5.

Table 2 shows the results of comparing the blending effects of the dialkylammonium nitrite salt and the dialkylamine salt for three types of lubricating oils having high hygroscopicity. The t / L of each oil is increased due to the blending of the salt.

Table 3 shows t / L when the above-mentioned dialkylammonium nitrite and amine salt were blended with polyalkylene glycol having a water content of 1000 ppm as a lubricating oil, and the operation was performed. The effect of adding nitrite and amine salt is recognized.

In addition to the trimethylolpropane esters shown in Table 2, neopentyl polyol esters include pentaerythritol ester, neopentyl glycol ester, trimethylolethane ester, dipentaerythritol ester [ASL.RTM. E-Transaction ASLE Trans., 29 No. 2185 (1985)],
There is a complex ester [Petrotech PTROTECH Vol. 8, No. 8, pp. 443-447 (1985)].

Table 4 shows that 1000% of water was added to these polyol esters.
The t / L is shown for the case of adding the rust preventive agent (dialkylamine salt or dialkylammonium nitrite) containing ppm and the case of not adding it. In each case, the effect of compounding the rust preventive agent is recognized.

R32, R134, and R14, which are considered as alternative refrigerants for R22
When the same tests as above were carried out for 3, R125 and the like, the same results as those in Tables 1 to 4 were obtained.

EFFECTS OF THE INVENTION The working medium for a refrigerator of the present invention has an effect of suppressing corrosion and flaking on the bearing surface of a refrigeration compressor, and can improve the life of an air conditioner or a refrigerator using the working medium. .

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a swash plate type compressor for a car air conditioner, and FIG. 2 is a vertical sectional view of a scroll type compressor. 1 ... Pulley, 2 ... Coil, 3 ... Shaft, 4,5 ...
… Roller bearings, 6 …… Swash plate, 7 …… Connecting rod, 8 …… Piston, 9 …… Piston support, 10 ……
Front cover, 11 …… cylindrical roller bearing, 12 …… wrap.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C10M 129: 40 105: 76 133: 06 133: 10) C10N 30:12 40:30 60:06 ( 72) Inventor Yutaka Ito 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Ltd. (72) Inventor Shigeki Komatsuzaki 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory Ltd. (72) Inventor Atsushi Kishi 2520 Takaba, Katsuta-shi, Ibaraki, Sawa Plant, Hitachi, Ltd. (72) Inventor, Toru Iizuka 800, Tomita, Taihei-cho, Shimotsuga-gun, Tochigi, Tochigi Plant, Hitachi, Ltd.

Claims (3)

[Claims] 1. A fluorocarbon refrigerant, (b) an aliphatic synthetic lubricating oil, and (c) general formulas [I] and [II]. (Wherein R ¹ is a cyclohexyl group, an isopropyl group, and R ² is an octyl group), and at least one of lead dialkylammonium nitrite and dialkylamine salt is contained in an amount of 0.01% by weight or more based on the lubricating oil. Working medium for refrigerators. 2. A synthetic lubricating oil comprising (a) a fluorohydrocarbon-based refrigerant, (b) at least one of polyalkylene glycol, neopentyl polyol ester and polyether-modified siloxane, (c) general formulas [I] and [I]. II) (Wherein R ¹ is a cyclohexyl group, an isopropyl group, and R ² is an octyl group), and at least one of lead dialkylammonium nitrite and dialkylamine salt is contained in an amount of 0.01% by weight or more based on the lubricating oil. Working medium for refrigerators. 3. A refrigerating apparatus provided with a refrigerating compressor having a roller bearing in a rotary drive unit, wherein (a) a fluorohydrocarbon-based refrigerant, (c) polyalkylene glycol, neo as a working medium of the refrigerating compressor. A synthetic lubricating oil comprising at least one of a pentyl polyol ester and a polyether modified siloxane, (c) General formulas [I] and [II] (Wherein, R ¹ is a cyclohexyl group, an isopropyl group, and R ² is an octyl group). A working medium containing at least one of dialkylammonium nitrite and dialkylamine salt in an amount of 0.01% by weight or more based on the lubricating oil is used. A refrigerating device characterized by the above.