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compressor, whose cranked shaft passes through the compressor casing so that the engine can be externally connected with the shaft is called open-type compressor. The seal shall be used in cases where the shaft comes through the compressor housing, to prevent leakage of refrigerant gas or air leakage in the case of a crankcase pressure below atmospheric pressure. Although designers are constantly developed better, seals, piercing accommodation is always a source of leakage. To avoid leakage print engine and compressor often enclosed in a single package. ....
Improved techniques for insulating the motor electrically have allowed motors to operate even though they are in contact with the refrigerant. In many designs the cold suction gas is drawn across the motor to keep the motor cool. Almost all small motor-compressor combinations used in refrigerators, freezers, and residential air conditioners are of the hermetic type. The only connections to the compressor housing are the suction and discharge fittings and electric terminals. Moisture in the system can be damaging to the motor; therefore dehydration of hermetic units before charging is essential. On larger hermetically sealed units the cylinder heads are usually removable so that the valves and pistons can be serviced. This type of unit is called semihermetic. |
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