Refrigeration – Automatic control – Withdrawing or adding refrigerant from or to normally closed...
Patent
1997-04-24
1998-09-15
Sollecito, John M.
Refrigeration
Automatic control
Withdrawing or adding refrigerant from or to normally closed...
62190, 62208, 622285, 62292, F25B 4500
Patent
active
058063293
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an air conditioner which can perform washing operation for removal of impurities within a refrigerant circuit, and to a method of controlling the washing operation.
BACKGROUND ART
In recent years, destruction of the ozone layer due to chlorine-containing refrigerants such as HCFC (hydrochlorofluorocarbon) 22 (CHClF.sub.2), which have conventionally been used in air conditioners and refrigerators, has become a great issue. As a result, HFC (hydrofluorocarbon) alternative refrigerants containing no chlorine have come to be used in place of HCFC 22 as a measure for preventing the destruction of the ozone layer.
As for the refrigerator oil, there is a need of using those matching the refrigerant used together. The refrigerator oil for use with the HFC refrigerants is exemplified by synthetic oils (for example, ester, ether, alkyl benzene oil and the like).
However, when such a synthetic oil is used as the refrigerator oil, unlike mineral oils that have conventionally been used, care must be taken about residual impurities other than the refrigerator oil and the refrigerant (i.e., contaminants, including residual oils such as cutting oil, rolling oil, tube-expanding oil and process oil which remain in the refrigerant circuit, as well as residual foreign matters such as metal wear powder and polymer). This is because these residual impurities may cause clogging or other malfunction of pressure reducing equipment (for example, small-diameter tubes such as capillary tubes and electro-expansion valves). Therefore, for systems with an HFC refrigerant and a synthetic oil employed, it has been a common practice to perform a flushing operation, i.e., a washing operation for the interior of the refrigerant system of the equipment in order to eliminate residual impurities.
However, since no effective method of washing operation has been yet established, equipment having such a special operation mode as washing operation mode has not been available, either. Accordingly, hitherto, the washing has been accomplished through an operation continued for an appropriate period of time in forced cooling operation mode or forced heating operation mode. Upon completion of the washing operation, components such as the compressor in which oil is liable to gather and residual impurities are contained in larger quantities, are removed from the system, and the oil is taken out of the removed components, thereby residual impurities are discharged. Further, new oil is re-charged and, finally, the removed components are assembled again to the system. However, it was often that only a very small quantity of residual impurities was discharged so that the refrigerant circuit was erroneously decided to be insufficiently washed. In such a case, the above sequence of work was repeated several times in order to remove the residual impurities to below a control level.
Since the conventional washing of the refrigerant circuit was done blindly as seen above, it was often that the washing operation was performed for a long time resulting in a problem that much time was required for washing. Further, because troublesome removal and re-assembly of components were needed at each time of discharge of residual impurities, i.e., oil replacement, much time was needed for the elimination of residual impurities eventually. In the conventional method, not only that the oil is replaced each time the washing operation is performed, but also that the residual-impurities eliminating work comprises many steps as described above, which required high costs. In addition to these problems, the conventional method has a problem of increased man-hours for development tests such as reliability test and evaluation test.
DISCLOSURE OF THE INVENTION
The present invention has been accomplished in view of these problems. An object of the present invention is therefore to provide an air conditioner and a method of controlling washing operation thereof, capable of performing the washing operation with good efficiency and in
REFERENCES:
patent: 4698983 (1987-10-01), Hechavarria
Oonuma Youichi
Taira Shigeharu
Daikin Industries Ltd.
Sollecito John M.
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