Compositions – Vaporization – or expansion – refrigeration or heat or energy... – With lubricants – or warning – stabilizing or anti-corrosion...
Reexamination Certificate
1998-06-26
2003-05-27
Toomer, Cephia D. (Department: 1714)
Compositions
Vaporization, or expansion, refrigeration or heat or energy...
With lubricants, or warning, stabilizing or anti-corrosion...
C062S114000, C062S468000
Reexamination Certificate
active
06569347
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a refrigerating machine oil comprised of a synthetic oil and a refrigerator employing the same.
BACKGROUND ART
Conventionally, an HCFC (hydrochloro-fluorocarbon) refrigerant has been mainly employed as a refrigerant of a refrigerator. However, since the HCFC refrigerant destroys the ozone layer in the atmosphere that surrounds the earth, an HFC. (hydrofluorocarbon) refrigerant having a small ozone destruction factor has been considered as a substitute for the HCFC refrigerant. HFC refrigerant hardly dissolves therein mineral oil that has conventionally been employed as a refrigerating machine oil, so that the lubricating performance of a compressor is significantly reduced. Therefore, it is proposed to employ a synthetic oil having a compatibility with the HFC refrigerant as a refrigerating machine oil.
The HFC refrigerant has an intense polarity since it has a combination of a hydrogen atom and a fluorine atom. In contrast to this, contaminations (soiled things) from deteriorated objects of cutting oil, rust preventive oil, hydraulic oil, wash oil, refrigerating machine oil and so on are nonpolar, while a synthetic oil such as an ether oil or the like has both a polar group and a nonpolar group. Therefore, the synthetic oil has a compatibility with the HFC refrigerant having a polarity and an affinity with nonpolar contaminations, therefore dissolving both of them. Then, in a compressor of the above refrigerator, the synthetic oil dissolving therein the contaminations is discharged together with the refrigerant from the compressor and made to circulate through a refrigerant circuit. When the HFC refrigerant is condensed in a condenser, the synthetic oil, which has an intense solubility in a liquid refrigerant, is dissolved in the liquid refrigerant, as a consequence of which the synthetic oil circulates through the refrigerant circuit together with the refrigerant. In this case, the affinity of the HFC refrigerant with the synthetic oil is stronger than the affinity of the contaminations with the synthetic oil, while the nonpolar contaminations are not dissolved in the HFC refrigerant having an intense polarity. Therefore, when the synthetic oil is dissolved into the liquid refrigerant, the contaminations that have been dissolved in the synthetic oil are separated from the synthetic oil and deposited in the liquid refrigerant. Then, the deposited contaminations, which have a high viscosity, adhere to narrow fluid passages of a capillary and an expansion valve, and they are eventually deposited to clog up passages.
The clogging of the capillary and the expansion valve disables the control of the refrigerant flow and causes an abnormal increase in temperature and a backward flow (return) of the fluid to the compressor, significantly impairing the reliability of the refrigerant circuit. Particularly when the ester oil is employed as the refrigerating machine oil, it causes a hydrolysis with water and tends to generate a sludge. In a refrigerator employing a capillary as a decompressor of the refrigerant circuit, the capillary tends to develop more clogging as the capillary tube has a smaller diameter, leading to a problem that it becomes inoperable as a refrigerator.
As a method for preventing the clogging of the capillary and expansion valve, it can be considered to clean the components on a strict standard, thoroughly control the setting and review components of a refrigerating system and the processing steps so that impurities do not enter during a manufacturing process and a setting process. However, these methods require much time as well as an increased number of processes as compared with the conventional cases. Furthermore, they employ an increased amount of detergent in the component cleaning stage and cause much energy consumption, consequently leading to a significant cost increase.
In contrast to this, a refrigerator which can cope with the HFC refrigerant employing only the refrigerating machine oil of the alkylbenzene oil that causes less capillary clogging has been put into practical use. However, the alkylbenzene oil, which is incompatible with the HFC refrigerant, has a property that it hardly dissolves therein the refrigerant gas. Furthermore, it is sometimes the case where a two-layer separation may be caused depending on the temperature range and the ratio of the refrigerant to the refrigerating machine oil. Accordingly, in a separate type air conditioner, an indoor unit and an outdoor unit are connected to each other by way of a long communicating pipe differently from the refrigerator in which all the components are integrated in a unit. Therefore, if the alkylbenzene oil incompatible with the HFC refrigerant is employed as the refrigerating machine oil, then the refrigerating machine oil discharged from the compressor hardly returns to the compressor since the viscosity of the refrigerating machine oil in the refrigerant circuit is high. Therefore, an air conditioner having a long communicating pipe has a problem that an abnormality occurs due to a seizure and abrasion caused by a shortage of refrigerating machine oil in the compressor.
Furthermore, when a large amount of liquid refrigerant lies in the compressor at a low environmental temperature of the compressor or when a large amount of liquid refrigerant returns to the compressor during defrosting, the refrigerating machine oil and the HFC refrigerant separate into two layers inside a dome of the compressor, as a consequence of which a refrigerant rich layer having a greater specific gravity stays in a lower portion of the dome. Then, the refrigerant rich fluid whose viscosity has been significantly reduced is consequently sucked from the inlet port of an oil pump provided in the lowermost portion of the dome of the compressor. A bearing of the compressor is normally designed on the supposition that the viscosity of the refrigerating machine oil is relatively high, according to which the size of the bearing and a frictional motive force at the bearing are considered. Therefore, if the refrigerant rich fluid whose viscosity is significantly reduced is sucked, then a thickness of oil film is reduced to cause a metal contact, and this leads to a problem that the bearing is damaged and the reliability of the compressor is significantly impaired.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of the present invention to provide a refrigerating machine oil which can easily remove a sludge generated in a refrigerant circuit without reviewing refrigerant system components nor processing steps and is easy to return to a compressor and refrigerator employing the same.
Another object of the present invention is to provide a refrigerating machine oil which can prevent a two-layer separation of oil and refrigerant into two layers inside a compressor and refrigerator employing the same.
In order to achieve the aforementioned objects, the present invention provides a refrigerating machine oil obtained by mixing a first synthetic oil comprised of an alkylbenzene oil with a second synthetic oil other than the alkylbenzene oil.
In regard to the refrigerating machine oil having the above construction, the present applicant has conducted various experiments and studies and discovered that the mixed oil obtained by mixing the first synthetic oil comprised of an alkylbenzene oil and the second synthetic oil (ether oil, ester oil, fluorine oil, carbonate oil or the like) other than the alkylbenzene oil exfoliated sludge generated on inner surfaces of refrigerant system components due to the contaminations (soiled objects) of cutting oil, rust preventive oil, hydraulic oil, wash oil and so on dissolved into a refrigerant. Therefore, according to the above refrigerating machine oil, the sludge adhered to the inner surfaces of a capillary and an expansion valve is exfoliated and removed by the alkylbenzene oil. Therefore, the sludge can be removed to prevent the capillary and the expansion valve from being clogged without reviewing the refrigerant system components no
Kita Koichi
Nomura Masaki
Oonuma Youichi
Taira Shigeharu
Yajima Ryuzaburo
Birch & Stewart Kolasch & Birch, LLP
Daikin Industries Ltd.
Toomer Cephia D.
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