JP2008002777A - Refrigeration cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigeration cycle device securing lubrication of an expander. <P>SOLUTION: Pressures in sealed containers of a compressor and the expander are maintained substantially the same as a pressure of a coolant compressed by the compressor, lubricating oil reservoirs are provided in the seal containers of the compressor and the expander, and a pressure equalizer is provided in an upper space in a neighborhood of a design oil level of each lubricating oil reservoir part. By this, lubricating oil levels in the compressor and the expander are maintained at the substantially same level, and a reliable refrigeration cycle device securing positive lubrication is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus effective for use in a vapor compression refrigeration air conditioner having an expander.

  Conventionally, from the viewpoint of environmental protection, refrigeration air conditioners using a carbon dioxide refrigerant that does not destroy the ozone layer and has a very low global warming potential have been developed. Because of the characteristics of carbon dioxide, the refrigeration efficiency (COP) is insufficient compared to a refrigeration air conditioner using chlorofluorocarbon as a refrigerant, and thus it is necessary to improve the refrigeration efficiency. Therefore, as shown in FIG. 4 (B), instead of the expansion valve 99 shown in FIG. 4 (A), in which the expansion stroke of the refrigerant 5 is an expansion close to isoenthalpy, the expansion stroke of the refrigerant 5 is an expansion close to isentropic. There is a refrigeration air conditioner 8 in which the refrigeration efficiency is improved by using the expanding machine 22 (see, for example, Patent Document 1 and Patent Document 2). A load device 280 for controlling the expansion stroke of the refrigerant 5 is attached to the expander 22.

  However, since the expander 22 has a sliding part, a seal part, etc., in the refrigeration air conditioner 8, it is necessary to supply the lubricating oil 6 to the expander 22. However, in the refrigeration air conditioner 8, the refrigerant 5 from which the lubricating oil 6 has been separated and removed by the oil separator 92 is supplied to the compressor 21 (FIG. 4B). That is, the lubricating oil 6 is supplied to the compressor 21, but the lubricating oil 6 is not supplied to the expander 22. As described above, if the lubricating oil 6 is not supplied to the expander 22, the durability and reliability of the sliding portion of the expander 22 are deteriorated, and the performance is reduced due to poor sealing of the piston ring and the seal portion. Problems such as leakage occurred.

In order to solve the above-mentioned problem, as shown in FIG. 5, between the compressor 21 and the radiator 16, an oil that separates the refrigerant 5 that has passed through the compressor 21 and the lubricating oil 6 contained therein. A separator 12 is provided. The oil separator 12 includes an oil return pipe for returning the lubricating oil 6 separated from the refrigerant 5 to between the evaporator 17 and the compressor 21, and the lubricating oil 6 to the radiator 16. A configuration has been proposed in which an oil feed pipe 14 that is fed into and from the expander 22 is disposed (see, for example, Patent Document 3). According to this configuration, it is possible to provide a refrigeration air conditioner that can sufficiently supply lubricating oil not only to the compressor but also to the expander.
Japanese Patent Laid-Open No. 10-19401 Japanese Patent Laid-Open No. 10-266983 JP 2001-141315 A

  However, when oil sufficient to lubricate the expander 22 is not discharged from the compressor 21, the sliding portion of the expander 22 cannot be reliably lubricated.

  Furthermore, the conventional structure with oil equalizing pipes and pressure equalizing pipes is common in refrigeration cycle systems that use multiple compressors. However, the temperature of the compressor is almost the same, so the position of the pressure equalizing pipe is provided at the top of the compressor. However, there was no problem in making the oil level uniform. However, when the compressor and expander are connected by a pressure equalizing pipe, the compressor oil level and the expander oil level are maintained at the same height by the action of the pressure equalizing pipe and oil leveling pipe when stopped, but the compressor pressure equalizing pipe connection is maintained during operation. There is a large difference between the density of the refrigerant from the oil level to the oil level and the density of the refrigerant from the pressure equalizing pipe connecting part of the expander to the oil level, resulting in the oil level on the expander side having a high density being pushed down. The oil level could not be secured, and it was difficult to ensure reliability.

The present invention solves the above-described conventional problems, and provides a sufficient efficiency and reliable supply of lubricating oil not only to the compressor but also to the expander to ensure reliability, and with a simpler configuration and a highly efficient refrigeration cycle. An object is to provide an apparatus.

  In order to solve the conventional problem, the refrigeration cycle apparatus of the present invention maintains the pressure in the sealed container of the compressor and the expander substantially the same as the pressure of the refrigerant compressed by the compressor. A lubricating oil reservoir is provided in the compressor's sealed container and the expander's sealed container, and the respective lubricating oil reservoirs are connected by an oil equalizing pipe. A pressure equalizing pipe is provided in the space. Accordingly, it is an object of the present invention to provide a highly efficient refrigeration cycle apparatus with a simpler structure while sufficiently and surely supplying not only a compressor but also an expander to ensure reliability.

  The refrigeration cycle apparatus of the present invention can achieve both high reliability and low cost, particularly in the case of increasing the efficiency of equipment using a carbon dioxide refrigerant whose refrigeration efficiency is insufficient compared to Freon.

  According to a first aspect of the present invention, there is provided a compressor composed of a compression mechanism section and a sealed container that houses an electric motor section, a radiator for cooling the refrigerant compressed by the compressor, an expansion mechanism section, and an electric motor section. A refrigerating cycle apparatus comprising: an expander configured with a sealed container for storage; an evaporator for evaporating the refrigerant expanded by the expander; and a refrigerant pipe for circulating the refrigerant therebetween, Lubricating oil reservoirs are provided in the airtight container of the compressor and the airtight container of the expander, and each lubricating oil reservoir is connected by an oil equalizing pipe, and the upper portion of each lubricating oil reservoir in the vicinity of the design oil level. A pressure equalizing pipe is provided in the space. As a result, the lubricating oil surfaces in the compressor and the expander can always be almost at the same height, so that a refrigeration cycle apparatus with high reliability can be provided.

  According to a second aspect of the present invention, one opening of the pressure equalizing pipe is connected to the upper oil level in the design of the compressor, and the expander and the pressure equalizing pipe can be transferred to the outer wall surface of the expander after piping approximately horizontally. In this state, the other opening is connected to the vicinity of the end plate of the expander, and a refrigeration cycle apparatus having the same high reliability as that of the first invention can be provided.

  According to a third aspect of the present invention, one opening of the pressure equalizing tube is connected to the upper end plate of the compressor or the vicinity thereof, and the compressor and the pressure equalizing tube are placed on the outer wall surface of the compressor in a state where heat can be transferred. The lubricating oil is lowered to the vicinity of the design oil level, and the other opening is connected to the upper part of the design of the lubricating oil of the expander, and the opening of the pressure equalizing pipe on the compressor side is By separating from the surface of the lubricating oil, it is possible to prevent the lubricating oil from entering the pressure equalizing pipe, and it is possible to provide a refrigeration cycle apparatus that ensures high reliability.

  In the fourth invention, in particular, the refrigerant of the first to third inventions is a high-pressure refrigerant, for example, carbon dioxide. As a result, high efficiency can be achieved even in equipment using carbon dioxide refrigerant, which has a large throttle loss in the expansion process compared to refrigeration air conditioners using chlorofluorocarbon as a refrigerant, so that refrigeration with high refrigeration efficiency can be achieved without destroying the global environment. A cycle device can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a refrigeration cycle apparatus according to a first embodiment of the present invention. Compression mechanism 21
a, a motor 21b and a sealed container 21c, a radiator 16 for cooling the refrigerant compressed by the compressor 21, an expansion mechanism 22a, a motor 22b and a sealed container 22c. This is a refrigeration cycle apparatus having an expander 22, an evaporator 17 for evaporating the refrigerant expanded by the expander 22, and a refrigerant pipe 11 for circulating the refrigerant between them. The pressure in each of the sealed containers of the compressor 21 and the expander 22 is a so-called high-pressure shell type that is the discharge pressure of the compressor 21. Further, lubricating oil reservoirs 21 d and 22 d are formed in the lower portions of the sealed containers, and the respective lubricating oil reservoirs are connected by an oil equalizing pipe 23. Further, a pressure equalizing pipe 24 is provided in the upper space in the vicinity of the designed oil level of each lubricating oil reservoir.

  In the refrigeration cycle apparatus configured as described above, the pressure at the opening of the pressure equalizing pipe is the same, but the oil level of the compressor and the oil level of the expander are refrigerant density at a height from the pressure equalizing pipe to the oil level, respectively. The oil level of the expander with low temperature and large refrigerant density is stable because it receives the pressure from the compressor, but the oil level of the expander is lower than the oil level of the compressor. The difference in the stable position between the machine oil level and the expander oil level can be kept small.

  Specifically, in the case of a refrigeration cycle apparatus using CO2, when the compressor discharge pressure is about 10 MPa, the discharge temperature is usually about 80 ° C., and the expander container temperature is about 30 ° C., Since the refrigerant density in the compressor is about 220 kg / m3, the refrigerant density in the expander is about 770 kg / m3, and the density of the lubricating oil is about 1000 kg / m3, the pressure equalizing pipe provided at a position 2 cm higher than the oil level Will have a refrigerant weight of 4.4 kg / m2 on the compressor oil level and a refrigerant weight of 15.4 kg / m2 on the expander oil level, and the expander oil level will be balanced 1.1 cm lower than the compressor oil level. . If the oil level difference between the stop and operation is about 1 cm, it can be used normally. However, if the pressure equalizing pipe is 20 cm away from the oil level, the oil level in the compressor and the oil level in the expander are stopped and operated. It will be 11 cm different from time to time, making stable lubrication difficult.

(Embodiment 2)
FIG. 2 shows a refrigeration cycle apparatus according to the second embodiment of the present invention.

  One opening of the pressure equalizing pipe 24 is connected to the upper design oil level of the compressor 21, and the expander 22 and the pressure equalizing pipe 24 can be transferred to the outer wall surface of the expander 22 after the pipe is placed almost horizontally. And the other opening is connected to the vicinity of the end plate of the expander 22. The pressure at the lower end of the rising portion 24 a of the pressure equalizing pipe 24 is the same as that of the pressure equalizing pipe opening of the compressor 21. Since the rising portion 24a is substantially the same as the temperature of the expander container and the refrigerant density is substantially equal to the refrigerant density in the expander, the pressure in the pressure equalizing pipe opening of the compressor is P, the refrigerant density in the expander is ρ, and the pressure equalizing pipe rises If the height of the section is h, the pressure in the pressure equalizing pipe opening of the expander is (P−ρ · h), and the pressure in the expander corresponding to the height of the horizontal section 24b of the pressure equalizing pipe is (P−ρ · h). ) + Ρ · h, which is the same effect as that of the first embodiment of the present invention. It is obtained.

(Embodiment 3)
FIG. 3 shows a refrigeration cycle apparatus according to the third embodiment of the present invention.

One opening of the pressure equalizing pipe 24 is connected to the upper part of the compressor 21, and the compressor 21 and the pressure equalizing pipe 24 are lowered on the outer wall surface of the compressor 21 in a state where heat can be transferred, and then arranged substantially horizontally. The other opening is connected to the upper vicinity of the lubricating oil surface of the expander 22, and the pressure at the lower end of the falling part 24 a of the pressure equalizing pipe is the same as the pressure inside the compressor 21, and the pressure equalizing pipe falling part 24a is almost the same temperature as the compressor container, and the refrigerant density is almost equal to the refrigerant density in the compressor. Therefore, the pressure in the pressure equalizing pipe opening of the compressor is P, the refrigerant density in the compressor is ρc, and the pressure equalizing pipe falls. Assuming that the height of the portion 24a is h, the pressure at the bottom of the pressure equalizing pipes is (P + ρc · h), and the pressure of the pressure equalizing pipe that opens to the expander is also (P + ρc · h). Further, since the pressure in the compressor corresponding to the height of the horizontal portion 24b is also (P + ρc · h), the effects as described in the first embodiment of the present invention can be obtained, and the pressure equalizing pipe opening on the compressor side can be obtained. Since the part is provided at a position higher than the lubricating oil surface, there is little possibility of the lubricating oil intruding into the pressure equalizing pipe, and even if the lubricating oil flows into the pressure equalizing pipe, it stays and prevents the pressure equalizing Since there is nothing, a highly reliable refrigeration cycle can be realized.

  As described above, the refrigeration cycle apparatus according to the present invention includes a compressor composed of a compression mechanism unit, an electric motor unit, and a sealed container that accommodates the compressor unit, and a radiator for cooling the refrigerant compressed by the compressor. An expander composed of an expansion mechanism section and an electric motor section, and an airtight container for storing the expansion section, an evaporator for evaporating the refrigerant expanded by the expander, and a refrigerant pipe for circulating the refrigerant therebetween The pressure in the sealed container of the compressor and the expander is kept substantially the same as the pressure of the refrigerant compressed by the compressor, and the sealed container of the compressor and the sealed container of the expander Lubricating oil reservoirs are provided inside, and the respective lubricating oil reservoirs are connected by oil equalizing pipes, and pressure equalizing pipes are provided in the upper space in the vicinity of the designed oil level of each lubricating oil reservoir. As a result, the lubricating oil surfaces in the compressor and the expander can be kept substantially on the same plane, the sliding portion can be reliably lubricated, and a refrigeration cycle apparatus with high reliability can be provided. It can be used for refrigeration cycle devices such as air conditioners, water heaters, and car coolers. Further, the compressor and the expander can be commonly applied to various types such as a reciprocating type, a screw type, a vane rotary type, a scroll type, a rolling piston type, and a swing piston type.

Refrigeration cycle diagram showing the refrigeration cycle in Embodiment 1 of the present invention. Refrigeration cycle diagram showing the refrigeration cycle in Embodiment 2 of the present invention. Refrigeration cycle diagram showing the refrigeration cycle in Embodiment 3 of the present invention. Refrigeration cycle diagram showing a conventional refrigeration cycle Refrigeration cycle diagram showing a conventional refrigeration cycle

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerating cycle 5 Refrigerant 11 Refrigerant piping 16 Radiator 17 Evaporator 21 Compressor 21a Compression mechanism part 21b Electric motor part 21c Sealed container 21d Lubricating oil reservoir 22 Expander 22a Compression mechanism part 22b Electric motor part 22c Sealed container 22d Lubricant oil reservoir

Claims (4)

A compressor composed of a compression mechanism section and a sealed container for housing the motor section; a radiator for cooling the refrigerant compressed by the compressor; and a sealed container for housing the expansion mechanism section and the motor section. A refrigeration cycle apparatus having a configured expander, an evaporator for evaporating a refrigerant expanded by the expander, and a refrigerant pipe for circulating the refrigerant between the expander, and in an airtight container of the compressor And a lubricating oil reservoir in the hermetically sealed container of the expander, each lubricating oil reservoir is connected by an oil equalizing pipe, and a pressure equalizing pipe is provided in the upper space near the design oil level of each lubricating oil reservoir. A refrigeration cycle apparatus characterized by that. A compressor composed of a compression mechanism section and a sealed container for housing the motor section; a radiator for cooling the refrigerant compressed by the compressor; and a sealed container for housing the expansion mechanism section and the motor section. A refrigeration cycle apparatus having a configured expander, an evaporator for evaporating a refrigerant expanded by the expander, and a refrigerant pipe for circulating the refrigerant between the expander, and in an airtight container of the compressor And a lubricating oil reservoir in the hermetically sealed container of the expander, each lubricating oil reservoir is connected by an oil equalizing pipe, and one opening of the pressure equalizing pipe is connected to the upper oil level in the design of the compressor. A refrigeration cycle apparatus characterized in that, after piping substantially horizontally, the other opening is connected to the end plate of the expander along the outer wall surface of the expander in a state where heat can be transferred to the expander and the pressure equalizing pipe. . A compressor composed of a compression mechanism section and a sealed container for housing the motor section; a radiator for cooling the refrigerant compressed by the compressor; and a sealed container for housing the expansion mechanism section and the motor section. A refrigeration cycle apparatus having a configured expander, an evaporator for evaporating a refrigerant expanded by the expander, and a refrigerant pipe for circulating the refrigerant between the expander, and in an airtight container of the compressor And a lubricating oil reservoir in the hermetically sealed container of the expander, each lubricating oil reservoir is connected by an oil equalizing pipe, one opening of the pressure equalizing pipe is connected to the upper end plate of the compressor or the vicinity thereof, Place the compressor and pressure equalizing pipe along the outer wall surface of the compressor in a state where heat can be transferred to the vicinity of the design oil level of the lubricant, and the upper part of the design oil level of the lubricant of the expander The other opening is connected to The refrigeration cycle apparatus. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the refrigerant is a high-pressure refrigerant, for example, carbon dioxide.

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