Refrigeration – Refrigeration producer – With lubricant handling means
Reexamination Certificate
2000-04-13
2001-05-29
Doerrler, William (Department: 3744)
Refrigeration
Refrigeration producer
With lubricant handling means
C062S084000, C062S475000, C062S470000
Reexamination Certificate
active
06237362
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to an oil separator for compressors of automobile refrigeration systems and, more particularly, to an internal oil separator installed within the compressor of such a refrigeration system and used for separating and recovering lubrication oil from discharged gas refrigerant before the refrigerant is discharged from the compressor through a refrigerant discharge line and feeding the recovered oil back to the frictional parts of the compressor.
2. Description of the Prior Art
As well known to those skilled in the art, a refrigeration system for automobiles typically comprises a compressor, a condenser, an expansion valve and an evaporator. In such a refrigeration system, the compressor adiabatically compresses low temperature and low pressure gas refrigerant, thus forming high temperature and high pressure gas refrigerant prior to discharging the refrigerant to a condenser. The condenser condenses the high temperature and high pressure gas refrigerant from the compressor through a heat exchanging process, thus forming saturated liquid refrigerant. The expansion valve throttles the saturated liquid refrigerant from the condenser, thus allowing the refrigerant to become a saturated wet vapor phase having low pressure. In the evaporator, the refrigerant from the expansion valve absorbs heat from its surroundings, thus becoming a saturated gaseous phase prior to returning to the compressor.
In such a refrigeration system for automobiles, the compressor is operated by the rotating force of the engine, which is selectively transmitted thereto through a pulley under the control of an electromagnetic clutch. The compressor thus sucks the saturated gas refrigerant from the evaporator and compresses the refrigerant by a rectilinear reciprocating action of a piston prior to discharging the refrigerant to the condenser. Such compressors have been typically and generally classified into two types, that is, reciprocating compressors and rotary compressors, in accordance with both the refrigerant compression styles and the structures of the compressors. In addition, the reciprocating compressors have been classified into two types, swash plate compressors and wobble plate compressors. On the other hand, the rotary compressors have been classified into two types, vane rotary compressors and scroll compressors.
A swash plate compressor comprises a front housing, and a rear housing assembled with the front housing into a single housing. A front cylinder is installed within the front housing, while a rear cylinder is installed within the rear housing. A plurality of double-head pistons are movably positioned within the bores of the front and rear housing so as to rectilinearly reciprocate relative to the bores. A drive shaft is rotatably installed in the compressor while passing through the central portions of the front and rear housings and the front and rear cylinders. A swash plate is inclinedly mounted to the drive shaft and is rotated along with the drive shaft, thus allowing the double-head pistons to rectilinearly reciprocate relative to the bores of the cylinders. A valve unit is installed in the gap between each of the front and rear cylinders and the interior surface of an associated one of the front and rear housings.
When the rotating force of an engine is applied to the drive shaft of the above swash plate compressor, the swash plate is rotated along with the drive shaft, thus allowing the double-head pistons to rectilinearly reciprocate within the bores of the front and rear cylinders. During such a reciprocating action of the pistons, refrigerant is sucked into the bores of the cylinders through a valve unit in the case of a suction stroke of the cylinders. On the other hand, refrigerant is compressed and discharged from the bores of the cylinders through another valve unit in the case of an discharge stroke of the cylinders.
In order to allow such a swash plate compressor to be smoothly operated, it is necessary to make refrigerant laden with lubrication oil. In such a case, the lubrication oil effectively circulates along with the refrigerant through the drive parts within the compressor during an operation of the refrigeration system, thus lubricating the gaps between the mechanically frictional drive parts within the compressor, such as the gaps between the pistons and cylinder bores.
When such lubrication oil circulates along with refrigerant within the refrigeration system as described above, the oil passes through the heat exchangers, such as the condenser and evaporator, and through the expansion valve and a variety of pipes and hoses. The oil is thus undesirably coated on the interior surfaces of the refrigerant passages within the refrigeration system and consumes the space of the interior cavity of the parts of the system, particularly, the heat exchangers. This finally reduces the fluidity of refrigerant within the refrigeration system in addition to a reduction in heat exchanging effect of the refrigeration system. Such a coated oil layer also increases the pressure drop within the heat exchangers, and so the operational effect of the refrigeration cycle is deteriorated. On the other hand, the circulation of oil through all the parts of the refrigeration system inevitably results in a variation in the amount of oil laden in the refrigerant fed to the compressor. Therefore, lubrication oil fails to be sufficiently supplied to the drive parts within the compressor, and so it is almost impossible to accomplish a desired lubrication effect for the frictional drive parts of the compressor. This causes such frictional drive parts of the compressor to be operated without being effectively lubricated, thus finally causing frictional damage or breakage of the drive parts and reducing the durability of the compressor. When refrigerant is laden with a large quantity of lubrication oil so as to allow the drive parts of the compressor to be sufficiently lubricated, the refrigerant may lose its intrinsic refrigerating function due to the oil. This finally reduces the refrigerating operational efficiency of the refrigeration system and increases the size of the system. It is difficult to design such an enlarged refrigeration system or to install the system at a limited area within the engine compartment of an automobile.
In an effort to overcome the above-mentioned problems, the automobile refrigeration systems are typically provided with oil separators for separating and recovering lubrication oil from discharged gas refrigerant of a compressor and feeding the recovered oil back to the compressor.
Such oil separators for compressors have been typically classified into two types, internal oil separators installed within compressors and external oil separators installed outside the compressors, in accordance with the position of the oil separators relative to the compressors. The two types of oil separators respectively have advantages and disadvantages as follows.
FIG. 16
is a circuit diagram of a refrigeration system provided with a conventional external oil separator. As shown in the drawing, the external oil separator
110
is installed on a refrigerant discharge line
112
outside the compressor
100
, and so the external oil separator
110
is so-called “a refrigerant discharge line oil separator” in the art. Such an oil separator
110
separates and recovers lubrication oil from refrigerant discharged from the compressor
100
through the discharge line
112
and stores the recovered oil in its oil chamber, and feeds the recovered oil back to the refrigerant suction line
111
of the compressor
100
through an oil flow controller (not shown), such as a capillary tube. The above oil separator
110
thus allows the lubrication oil to repeatedly circulate within the compressor
100
so as to lubricate the drive parts (not shown) of the compressor
100
without being fed to the other parts of the refrigeration system. In the drawing, the reference numerals
130
,
140
,
150
and
160
Doerrler William
Halla Climate Control Corp.
Shulman Mark
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