Refrigeration – Refrigeration producer – Compressor-condenser-evaporator circuit
Reexamination Certificate
1999-01-22
2001-02-20
McDermott, Corrine (Department: 3744)
Refrigeration
Refrigeration producer
Compressor-condenser-evaporator circuit
C062S199000, C062S513000, C062S524000
Reexamination Certificate
active
06189335
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a multi-stage compressing refrigeration device for compressing a refrigerant in multiple stages using a plurality of compressing means.
DESCRIPTION OF THE RELATED ART
For a conventional refrigeration device for use in a refrigerator, an air conditioner, and the like, as disclosed in Japanese Patent Publication No. 30743/1995 (F04C23/00), a rotary type compressor is used, in which two compressing means each comprising a rotary cylinder and a roller rotating inside the cylinder are contained in the same closed container. The compressing means are operated as low-stage and high-stage compressing means. The refrigerant gas compressed in one stage by the low-stage compressing means is sucked by the high-stage compressing means, so that the refrigerant is multi-stage compressed.
According to the multi-stage compressing refrigeration device, there is an advantage that a high compression ratio can be obtained while the torque fluctuation in one compressing operation is suppressed.
However, especially when a refrigerant having a high specific heat ratio is used in the conventional multi-stage compressing refrigeration device, the temperature of the gas refrigerant of the low-stage compressing means sucked by the high-stage compressing means is raised, and input is disadvantageously raised. Moreover, the temperature of the gas refrigerant discharged from the high-stage compressing means is also raised. Therefore, when ester oil (e.g., polyol ester or POE) is used as a lubricating oil, the lubricating oil causes hydrolysis by heat, and acid and alcohol are generated. Since sludge is generated as the acid, a capillary tube is disadvantageously clogged, while lubricating properties are deteriorated.
Moreover, since the refrigeration effect is also lowered, efficiency (result coefficient) is disadvantageously deteriorated.
Furthermore, during pull-down when equipment is installed or in another transient condition, even if multi-stage compression is performed, the enhancement of efficiency cannot be expected. On the contrary, when operation by one-stage compression of each compressing means is performed, the displacement volume is increased, and an efficient operation can be realized. Conversely, during nighttime or in another low-load condition, multi-stage compression is unnecessary.
On the other hand, in a conventional household refrigerator provided with a cold storage chamber and a freezing chamber, air cooled by an evaporator usually installed on the side of the freezing chamber is circulated in each chamber for cooling. In this case, the temperature of the freezing chamber is controlled by controlling a compressor, but the temperature of the cold storage chamber is controlled by regulating the circulation amount of cool air flowing into the freezing chamber. Therefore, the temperature of the freezing chamber should be subordinate to the temperature of the freezing chamber.
To solve the problem, there is proposed a device in which freezing and cold storage chambers are provided with freezing and cold storage chamber evaporators, respectively, so that each chamber is directly cooled by the evaporator installed therein. In this case, when the refrigerant is supplied to the evaporators by one ordinary compressor, pressure adjustment becomes difficult, while refrigeration effect and operation efficiency are disadvantageously deteriorated.
SUMMARY OF THE INVENTION
The present invention has been developed to solve the aforementioned conventional technical problems, and an object thereof is to provide a multi-stage compressing refrigeration device in which a plurality of compressing means are used to compress a refrigerant in multiple stages, so that reliability is enhanced, input is reduced, refrigeration effect is improved, and efficiency is increased.
In the multi-stage compressing refrigeration device of the present invention, low-stage compressing means and high-stage compressing means, a condenser, first expanding means, an intermediate evaporator, second expanding means and a main evaporator constitute a refrigeration cycle. A refrigerant flowing out of the condenser is branched into one refrigerant passed to the intermediate evaporator via the first expanding means and the other refrigerant passed to the main evaporator via the second expanding means. Heat exchange is performed between the refrigerant flowing into the second expanding means and the intermediate evaporator, the refrigerant flowing out of the main evaporator is sucked by the low-stage compressing means, and the refrigerant flowing out of the intermediate evaporator is sucked by the high-stage compressing means together with the refrigerant discharged from the low-stage compressing means.
According to the present invention, the low-stage and high-stage compressing means, the condenser, the first expanding means, the intermediate evaporator, the second expanding means and the main evaporator constitute the refrigeration cycle. The refrigerant flowing out of the condenser is branched in one refrigerant passed to the intermediate evaporator via the first expanding means and the other refrigerant passed to the main evaporator via the second expanding means. Additionally, the refrigerant flowing out of the main evaporator is sucked by the low-stage compressing means, and the refrigerant flowing out of the intermediate evaporator is sucked by the high-stage compressing means together with the refrigerant discharged from the low-stage compressing means. Therefore, while the torque fluctuation in one compressing operation in the compressor is suppressed, a high compression ratio can be obtained. Additionally, the temperature of the gas refrigerant sucked by the high-stage compressing means can be lowered. Therefore, input reduction can be attained. Moreover, the temperature of the gas refrigerant discharged from the high-stage compressing means is also lowered. For example, even when ester oil is used as a lubricating oil, the generation of POE problem or the deterioration of lubricating properties can be prevented.
Especially, since the heat exchange is performed between the refrigerant flowing into the second expanding means and the intermediate evaporator, the refrigeration effect is increased relative to the refrigerant circulation amount in the main evaporator. Therefore, the efficiency can be enhanced.
Here,
FIG. 4
shows the relationship of a ratio D
2
/D
1
of displacement volume D
1
of the low-stage compressing means and displacement volume D
2
of the high-stage compressing means and the result coefficient. As clearly seen from
FIG. 4
, the result coefficient exhibits a mountain-shaped characteristic with the vicinity of the displacement volume ratio D
2
/D
1
of 30% (0.3) being a peak. Subsequently, the throttle amount of the first expanding means is changed to change the refrigerant temperature in the intermediate evaporator. When the peak value on the curve of
FIG. 4
in each refrigerant temperature is plotted as shown in
FIG. 6
, a mountain-shaped characteristic is obtained as shown in
FIG. 5
or
6
. A line shown in the lowermost portion of
FIG. 6
shows the result coefficient of one-stage compressing refrigeration device.
Specifically,
FIG. 5
or
6
shows the relationship of the refrigerant temperature in the intermediate evaporator and the result coefficient. Additionally, since the refrigerant temperature in the intermediate evaporator is set in the range of −10° C. to +25° C. in the present invention, as clearly seen from
FIG. 6
, the result coefficient can remarkably be improved as compared with the one-stage compressing refrigeration device.
Moreover, in the multi-stage compressing refrigeration device of the present invention, the ratio D
2
/D
1
of the displacement volume D
1
of the low-stage compressing means and the displacement volume D
2
of the high-stage compressing means is set in the range of 0.35±0.15.
As clearly seen from
FIG. 4
, the result coefficient forms the mountain-shaped characteristic with the vic
Ebara Toshiyuki
Ishiai Yoshio
Komatsubara Takeo
Tadano Masaya
Darby & Darby
McDermott Corrine
Norman Marc
Sanyo Electric Co,. Ltd.
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