KR100199281B1 - Lubricating oil composition for refrigerator compressor for reducing sound level - Google Patents

Abstract

The present invention provides a lubricant composition for a refrigeration compressor, the composition comprising a chlorine-free hydrofluorocarbon-based refrigerant, a lubricant, ester oil having at least two ester bonds in the molecule, a hydrolysis stabilizer and an oxidative stabilizer Furthermore, the foaming agent is characterized by containing silicone oil in an amount of 0.001 to 0.01% by weight.

By using such a lubricant composition, the noise by the generation | occurrence | production of a bubble during operation of a compressor can be effectively reduced.

Description

Lubricating oil composition for refrigerator compressor for reducing sound level

Technical Field

The present invention relates to attenuation of noise generated in a refrigeration compressor, and more particularly, a lubricant composition used in a refrigeration cycle and a refrigerant compressor, which contains a fluorocarbon refrigerant containing no chlorine as a refrigerant, and as a foaming agent. The present invention relates to a lubricant composition for a refrigeration compressor that contains a silicone-based oil as a foaming agent so that noise generated during operation of the compressor can be reduced.

Conventional technology

In a reciprocating compressor for refrigerators, oil noise generated at the start-up and operation of the compressor is often caused by irregularities of lubricant bubbles generated during operation of the compressor. Mineral oil-based oils used in conventional CFC-12 (Fron 12, dichlorodifluoromethane; CCl2F2) refrigerants are mixed with the refrigerant at a certain temperature, causing bubbles to be generated more than necessary. This solves the problem of oil noise generated during compressor operation. However, hydrofluorocarbon (HFC) type refrigerants, such as HFC-134a (pron 134a, 1,1,1,2-tetrafluoroethane), which are used in place of CFC-12 refrigerants which cause serious environmental pollution problems; CH2FCF3) In the case of refrigerant, ester oil used as lubricant has good solubility and solubility, but when bubble is separated from oil, bubble phenomenon is irregular and particle size of formed bubble is very large, which causes irregular noise in lubrication system. To provide.

Therefore, it is an object of the present invention to attenuate the noise of a compressor using a hydrofluorocarbon refrigerant.

Figures 1a and 1b is a picture showing the foam form at 24 ℃ and 93.5 ℃ of the ester oil-containing lubricant containing 0.003wt% foaming agent according to the present invention, Figure 1c is 0.003wt% foaming agent according to the present invention A graph showing the noise phenomenon of a compressor using an ester oil-containing lubricant.

Figure 2a and Figure 2b is a picture showing the foam form at 24 ℃ and 93.5 ℃ of the ester oil-containing lubricant containing 0.01wt% foaming agent according to the present invention, Figure 2c is 0.01wt% foaming agent according to the present invention A graph showing the noise phenomenon of a compressor using an ester oil-containing lubricant.

3a and 3b are photographs showing bubble shapes at 24 ° C. and 93.5 ° C., respectively, of an ester oil-free lubricant containing no foaming agent according to the invention, and FIG. 3c is an ester oil containing no foaming agent according to the invention. -Graph showing noise phenomena of compressor using lubricant.

4 to 6 are graphs comparing noise values at the main frequencies of a compressor using an ester oil-containing lubricant containing a foaming agent and an ester oil-containing lubricant containing no foaming agent according to the present invention.

In order to achieve the above object, the present invention provides a lubricating composition for a refrigerant containing no chlorine, comprising a ester oil, a foaming agent, a hydrolysis stabilizer, and an oxidizing stabilizer, wherein the foaming agent is a dimethyl represented by the following formula (I): A lubricant composition is provided which contains polysiloxane in an amount of 0.001-0.01 wt%.

The above and other objects, as well as advantages and features of the present invention will be apparent to those skilled in the art by the following detailed description.

Hereinafter, the present invention will be described in more detail.

According to the present invention, by adding a specific foaming agent to a lubricant composition for a compressor using a Pron-134a refrigerant, the bubble irregularity is increased during the operation of the compressor by increasing the precision of the bubbles and making the size of the bubbles fine. Occurrence of abnormal noises caused by can be suppressed.

In the lubricant composition for refrigerants of the present invention, the refrigerant refers to a fluorocarbon (HFC) type refrigerant containing no chlorine, and the ester oil has two or more ester bonds in the molecule and has a viscosity at 40 ° C of 2-35. cSt and two or more fatty acid ester oils having a viscosity of 1-6 cSt at 100 ° C. In particular, esters of side chain fatty acids having 2 to 10 carbon atoms and polyhydric alcohols such as neopentyl glycol (NPG), trimethyloalkylpropane (TMP), pentaerythritol (PE), or dipentaerythritol (DPET) in ester oils. What is produced by the reaction is preferably used.

Representative examples of the chlorine-containing hydrofluorocarbon refrigerant used in the present invention include difluoromethane (HFC 32 or R32), pentafluoroethane (HFC 125), 1,1,2,2- Tetrafluoroethane (HFC 134), 1,1,1,2-tetrafluoroethane (HFC 134a), 1,1,2-trifluoroethane (HFC 143), 1,1,1-trifluoro Ethane (HFC 143a), 1,1-difluoroethane (HFC 152a), monofluoroethane (HFC 161), and the like. These can be used alone or as a mixture of two or more thereof, and in particular, HFC-134a is preferably used in the present invention. In the composition of the present invention, the amount of the components other than the ester oil is not particularly limited, and the range of the amount that can achieve the object of the present invention can be determined by those skilled in the art. For example, it can select suitably in the range of 1-5000 ppm.

The lubricant composition for refrigerants of the present invention may contain, in addition to ester oils, foaming agents, hydrolysis stabilizers, extreme pressure agents and oxidative stabilizers. As the hydrolysis stabilizer, the extreme pressure agent, and the oxidation stabilizer, any one conventionally used in the art can be used without limitation, and the type and amount thereof can be easily selected by those skilled in the art. Generally, however, epoxy-based ones are used in an amount of 1-5000 ppm, and oxidative stabilizers are used in an amount of 1-5000 ppm of DBPC (di-tertiary-butyl-paracresol).

On the other hand, as the foaming agent which characterizes the present invention, a silicone oil is used, and preferably, dimethylpolysiloxane represented by the general formula I as described above is used in an amount of 0.001-0.01 wt%.

Hereinafter, the present invention will be described in more detail with reference to various examples, but the present invention is not limited to these examples.

Examples 1-2 and Comparative Example 1

As ester oils, those having a 40 ° C. viscosity of 14.5 to 16.5 cst, a 100 ° C. viscosity of 3.2 to 3.5 cst, and branched fatty acids having 8 carbon atoms, neopentyl glycol, and pentaerythritol were ester-bonded by 50% each. As an additive, 1000 ppm of an epoxy hydrolysis stabilizer and 2500 ppm of an oxidation stabilizer (DBPC) were used.

And a lubricant composition (Example 1) containing 0.003% by weight of the foaming agent together with the above components, a lubricant composition (Example 2) containing 0.01% by weight of the foaming agent, and a lubricant composition containing no foaming agent (Comparative Example 1) The bubble phenomena were observed at 24 ° C. and 93.5 ° C. in three freezer compressors, respectively, and tested by ASTM D892.

Figures 1a and 1b is a picture showing the foam form at 24 ℃ and 93.5 ℃ of the ester oil-containing lubricant containing 0.003wt% foaming agent according to the invention, respectively, Figures 2a and 2b is a foaming agent according to the present invention A photograph showing bubble shapes at 24 ° C. and 93.5 ° C. of an ester oil-containing lubricant containing 0.01 wt%, respectively, and FIGS. 3A and 3B show 24 ° C. of an ester oil-containing lubricant containing no foaming agent according to the present invention. It is a photograph showing the bubble shape at 93.5 degreeC, respectively.

As can be seen from the results of Figures 1a to 3b, in the case of the lubricant composition containing the foaming agent according to the present invention to form a bubble of uniform and fine size and shape.

In each case, the bubble level at 24 ° C. was 10-300 ml and the bubble level at 93.5 ° C. was 10-100 ml when the foam shape and size were measured by ASTM D892 method. The size of bubbles was uniformly distributed at 0.5-1 mm.

Examples 3-4 and Comparative Example 2

The compressor was operated under the same conditions as in Example 1 using a lubricant composition having the same composition as in Examples 1 to 2 and Comparative Example 1, and the noise phenomenon of the actual reciprocating compressor according to the presence / absence of the use of the foaming agent was found through a test. saw. Three compressors were used for the test for each composition.

1. Noise test condition

Noise tests were conducted under Calorimeter standard conditions.

① Teva: -23.3 ℃ ② Tcond: 54.4 ℃ ③ Tllq: 32.2 ℃

④ Tsuc: 32.2 ℃ ⑤ Tamb: 32.2 ℃

The saturation pressure for each temperature is shown in Table 1 below, and noise was measured at four locations around the compressor at a position of 1/2 of the total height of the compressor and 15 cm away from the compressor.

Noise was measured by RION's SOUND PRESSURE LEVEL METER, and COMP operation was measured under CALORIMETER conditions. In addition, the periodic noise phenomenon in the RION CHART during noise measurement refers to the phenomenon in which PEAK occurs more than 2dB periodically.

For noise measured under these conditions, the peak value should not exceed 35dB in the frequency band below 1KHz.

2. Test result

The noise measurement results in the case of using the lubricant composition according to Examples 3-4 and Comparative Example 2 are shown in Figs. 1C, 2C, and 3C, respectively.

As can be seen from the results shown in FIGS. 1C, 2C, and 3C, the lubricant composition to which the silicone-based foaming agent is added according to the present invention has the effect that the noise value is reduced and the periodic noise does not appear at the same time as a result of the operation test of the actual compressor. Although obtained (FIGS. 1C and 2C), in the operation test of the compressor using the lubricant composition of the comparative example which does not contain a silicone foam agent, the noise value was also high and periodic noise was also severe.

In addition, when the content of the foaming agent was about 0.003wt%, the noise was the lowest, and the periodic noise was also significantly reduced.

Example 5 and Comparative Example 3

The composition is the same as that of Example 1, except for using a lubricant composition for compressors (Example 5) containing dimethylpolysiloxane in an amount of 0.003% by weight as a foaming agent or a lubricant composition (Comparative Example 3) containing no dimethylpolysiloxane. Noise was measured in the same manner as in Example 3 for the three compressors, and the test results for the three compressors are shown in Tables 2-4. And the noise value by the composition by Example 5 and the comparative example 3 was compared through the graph about each compressor, and the result is shown to FIGS. 4-6. 4 to 6. -◇-shows Example 5 and-■-shows comparative example 3.

From the results in Table 2-5 and Figs. 4-6, it is confirmed that the lubricant composition using dimethylpolysiloxane as the foaming agent effectively attenuates the noise of the compressor and prevents the periodic noise from appearing. On the other hand, in the case of the lubricant composition without using the foaming agent it can be seen that the noise value is high and the periodic noise is also severe.

Claims (4)

In a lubricant composition for a refrigeration compressor comprising a hydrofluorocarbon refrigerant containing no chlorine, an ester oil having at least two ester bonds in a molecule as a lubricant, a hydrolysis stabilizer, and an oxidative stabilizer, wherein the composition is a silicone oil as a foaming agent. In an amount of 0.001 to 0.01% by weight; The ester oil is an ester of a branched fatty acid having 2 to 10 carbon atoms with a polyhydric alcohol such as neopentyl glycol (NPG), trimethyloalkylpropane (TMP), pentaethyltritol (PE), or dipentaerythritol (DPET). A lubricant composition having two or more ester bonds produced by a reaction in a molecule, having a viscosity at 40 ° C of 2-35 cSt, and a viscosity at 100 ° C of 1-6 cSt. The lubricant composition according to claim 1, wherein the foaming agent is dimethylpolysiloxane represented by the following formula (I). [Formula 1] 3. The lubricant composition of claim 1 or 2 wherein the foaming agent is used in an amount of about 0.003% by weight. The lubricant composition according to claim 1 or 2, wherein the hydrofluorocarbon refrigerant is 1,1,1-2-tetrafluoroethane.