JP2007113815A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure lubrication of an expander of a refrigerating cycle and to improve reliability and efficiency thereof. <P>SOLUTION: A compressor 21 and the expander 22 are fixed to each other, and connected by an oil equalizing tube and a pressure equalizing tube to keep pressure in sealed containers approximately same as a pressure of a refrigerant compressed by the compressor 21, and to equalize oil levels of lubricant reservoirs 21d, 22d respectively mounted in the sealed container 21c of the compressor and the sealed container 22c of the expander. Thus proper amounts of lubricants can be respectively secured in the compressor and the expander to lubricate a sliding portion, the compressor and the expander can be easily received in a refrigerating system, and the compact refrigerating system of high reliability can be provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus 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, by using an expander 22 in which the expansion stroke of the refrigerant 5 is expanded near isentropy, instead of the expansion valve that expands the expansion stroke of the refrigerant 5 near isentropic, the refrigeration efficiency is increased. There is a refrigerating and air-conditioning machine 8 that improves (see, for example, Patent Document 1 and Patent Document 2). The expander 22 includes a load device 280 for controlling the expansion stroke of the refrigerant 5 and a expander 22 that is coaxially connected to the compressor.

  The expander 22 has a function of converting the energy of the refrigerant into rotational energy and assisting the required power of the compressor. Depending on the configuration, the expander 22 collects electric power with the generator or directly transmits the rotational force to the compressor through the rotating shaft. Can be divided into

  If the compressor and the shaft are shared, the compressor and the expander are present in the same sealed container, so the dimensions are almost the same as the dimensions of the compressor alone, except for the axial length. In addition, although the problem related to the distribution of the lubricating oil is solved, the amount of refrigerant at the inlet of the expander is limited because the rotating shaft is shared in spite of the different refrigerant flow rates of the compressor and the expander in various operating conditions. In order to avoid this, it is necessary to provide a variable capacity mechanism.

  On the other hand, the compressor and the expander have separate sealed containers, and the expander that recovers the expansion energy by electric power can select the rotation speed between the compressor and the expander, so the energy of the refrigerant entering the expander can be recovered without waste. However, since the sealed container is a separate body, it has a drawback that it is difficult to hold the lubricating oil, and also has a disadvantage that it is necessary to secure a place for the expander when the device is incorporated.

In order to solve the above-described problem, an oil separator that separates the refrigerant 5 that has passed through the compressor 21 and the lubricating oil 6 contained therein is provided between the compressor 21 and the radiator 16 shown in FIG. The oil separator 12 is provided with 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 with the radiator 16 and the expander. A configuration has been proposed in which an oil feed pipe 14 that feeds between the two is provided (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, according to the conventional configuration, when the oil separator 12 has a low oil separation capability, the sliding portion of the expander 22 or the compressor 21 cannot be reliably lubricated. . Even if the oil separator 12 is reliably separated, the oil return pipe 13 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 are provided. Unless the distribution of the oil return amount of the oil feed pipe 14 sent between the radiator 16 and the expander 22 is appropriately controlled according to the load of the expander 22 or the compressor 21, the reliability of the compressor or the expander It has a problem of reducing the performance. In addition, the oil return pipes 13 and 14 and the oil separator 12 must be newly provided, resulting in an increase in production cost.

  Furthermore, as disclosed in Patent Document 2, it is conceivable that the compressor and the expander are housed in the same sealed container and share the rotating shaft and the lubricating oil reservoir. However, the compressor and the expander are necessary in various operating conditions. The refrigerant flow rate is different, and it is necessary to adjust the required refrigerant flow rate by limiting the amount of refrigerant at the inlet of the expander or by expanding the throttle, and in order to avoid this, there is a disadvantage that it is necessary to make a variable capacity mechanism .

  The present invention solves the above-described conventional problems, and wasteful recoverable energy of the refrigerant while ensuring reliability by supplying lubricating oil sufficiently and surely not only to the compressor but also to the expander. An object of the present invention is to provide a refrigeration cycle apparatus that is small and easy to handle without having to do so.

  In order to solve the conventional problem, a refrigeration cycle apparatus according to the present invention cools a compressor composed of a compression mechanism section and a sealed container that houses an electric motor section, and a refrigerant compressed by the compressor. , An expander composed of an expansion mechanism section and a sealed container that houses the generator section, an evaporator for evaporating the refrigerant expanded by the expander, and circulating the refrigerant therebetween The compressor and the expander are fixed so that the lubricating oil surface of the compressor and the lubricating oil surface of the expander are substantially flush with each other, and are lower than the lubricating oil surface. The oil equalizing pipe and pressure equalizing pipe are composed of simple pipes with no relative movement between the compressor and the expander by connecting the oil equalizing pipe communicating with the position and the pressure equalizing pipe communicating between the positions higher than the lubricating oil surface. Can be used at low cost. While reliably supplied to ensure the reliability divide, it is possible to provide a highly efficient refrigeration cycle apparatus.

  The refrigeration cycle apparatus of the present invention can achieve high reliability, high efficiency, and ease of handling, particularly in the case of increasing the efficiency of equipment using a carbon dioxide refrigerant that has insufficient refrigeration efficiency compared to Freon. it can.

  A first invention is a compressor constituted by a compression mechanism part and a sealed container that houses an electric motor part, a radiator for cooling the refrigerant compressed by the compressor, an expansion mechanism part, and a generator part A refrigerating cycle apparatus having an expander configured with a sealed container for storing the gas, an evaporator for evaporating the refrigerant expanded by the expander, and a refrigerant pipe for circulating the refrigerant therebetween, The compressor and the expander are fixed so that the lubricating oil surface of the compressor and the lubricating oil surface of the expander are substantially the same surface, and the oil leveling pipe and the lubricating oil surface communicate with each other at a position lower than the lubricating oil surface. By connecting the high positions with pressure equalizing pipes communicating with each other, it is possible to provide a refrigeration cycle apparatus in which a highly reliable combination of a compressor and an expander can be realized in a compact and compact manner.

  According to a second aspect of the invention, the oil equalizing pipe and the pressure equalizing pipe are divided into two at a substantially central portion in the longitudinal direction, and fixed to the compressor and the expander by welding or brazing, respectively. At the time of fixing, the oil equalizing pipe and the pressure equalizing pipe are sealed and fixed together by welding or brazing, so that a small and compact compressor and expander can be combined easily, so a small and inexpensive refrigeration cycle apparatus can be obtained. Can be provided.

According to a third aspect of the invention, the compressor and the expander are fixed to the same leg, so that the center of gravity combining the compressor and the expander is disposed on the leg, and vibration generated by the compressor and the expander is generated. It can be received by the same leg, and the refrigerator main body can be easily mounted.

  In the fourth invention, in particular, the refrigerant of the first and second inventions is carbon dioxide which is a high-pressure refrigerant. 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 that use chlorofluorocarbon as a refrigerant. Therefore, refrigeration with high refrigeration efficiency without destroying the global environment. A cycle device can be provided.

  In particular, the fifth invention uses the lubricating oil of the fourth invention mainly composed of polyalkylene glycol. As a result, since carbon dioxide and polyalkylene glycol have low compatibility, the liquid level of the lubricating oil in the hermetic container can be restrained from rising due to the refrigerant being melted, so the circulation rate of the lubricating oil during steady operation can be reduced. Can be small. As a result, since the performance of the radiator and the evaporator can be improved, a more efficient refrigeration cycle apparatus 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. A compressor 21 composed of a compression mechanism portion 21a, an electric motor portion 21b, and a sealed container 21c, a radiator 16 for cooling the refrigerant 5 compressed by the compressor 21, an expansion mechanism portion 22a, and an electric motor portion 22b are sealed. The refrigeration cycle apparatus 1 includes an expander 22 including a container 22c, an evaporator 17 for evaporating the refrigerant 5 expanded by the expander 22, and a refrigerant pipe 11 that circulates the refrigerant therebetween. The compressor 21 and the expander 22 are fixed by a fixing member 27, and the pressure in each sealed container 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. Yes. Furthermore, lubricating oil reservoirs 21 d and 22 d are formed in the lower part of the sealed container, and are connected by an oil equalizing pipe 23. These lubricating oil reservoirs 21d and 22d can lubricate the sliding portions in the compressor 21 and the expander 22, and a refrigeration cycle in which a highly reliable combination of the compressor and the expander can be realized in a compact manner. A device can be provided.

(Embodiment 2)
FIG. 2 shows a compressor and an expander part of the refrigeration cycle apparatus according to the second embodiment of the present invention. The compressor oil equalizing pipe 23a and pressure equalizing pipe 24a are fixed to the compressor, and the expander oil equalizing pipe 23b and pressure equalizing pipe 24b are fixed by welding or brazing at positions corresponding to the expander, respectively. A compact compressor and expander combination can be easily realized by sealing and fixing the oil equalizing pipe and the pressure equalizing pipe formed with the in-wax at the time of fixing by welding or brazing. 2a shows a situation before the compressor and the expander are fixed, and FIG. 2b shows a situation after the compressor and the expander are fixed.

(Embodiment 3)
FIG. 3 shows a refrigeration cycle apparatus according to the third embodiment of the present invention. Since the compressor and the expander are fixed to the same leg, the combination of the compressor and the expander can be handled as one component of the refrigeration cycle, which facilitates the manufacture of the refrigerator.

When the refrigerant is a high-pressure refrigerant, for example, carbon dioxide, the throttle loss in the expansion process is larger than that of a refrigeration air conditioner using Freon as the refrigerant. In this case, if this configuration that can be operated with increased reliability of the expander 22 is used, the efficiency of the equipment can be improved even if carbon dioxide refrigerant is used. An apparatus can be provided.

  In addition, when a lubricating oil mainly composed of polyalkylene glycol is used as the lubricating oil, since the compatibility of carbon dioxide and polyalkylene glycol is low, the liquid level of the lubricating oil in the sealed container is increased due to the melting of the refrigerant. Therefore, it is possible to reduce the change in the liquid level of the lubricating oil pool due to operating conditions and pressure. Therefore, the total amount of lubricating oil circulating in the outside of the hermetic container increases as the liquid levels of the lubricating oil reservoirs 21d and 22d of both the compressor 21 and the expander 22 rise as expected in the case of a highly compatible lubricating oil. Thus, the problem of reducing the performance of the radiator 16 and the evaporator 17 can be avoided, so that a more efficient refrigeration cycle apparatus can be provided.

  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 compressor and the expander are integrally fixed, and the pressure in the sealed container is kept substantially the same as the pressure of the refrigerant compressed by the compressor, and the compressor is installed in the sealed container. A lubricating oil reservoir is provided in an airtight container of an expander and connected by an oil equalizing pipe. As a result, the oil level of the lubricating oil that lubricates the sliding portions in the compressor and the expander can be secured, and a refrigeration cycle apparatus that ensures high reliability can be provided. Applicable to refrigeration cycle devices such as 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.

The block diagram which shows the refrigerating-cycle apparatus in Embodiment 1 of this invention. The schematic diagram which shows the assembly | attachment state of the compressor and expander in Embodiment 2 of this invention. The schematic diagram which shows the assembly | attachment state of the compressor and expander in Embodiment 3 of this invention. Configuration diagram showing a conventional refrigeration cycle apparatus Configuration diagram showing a conventional refrigeration cycle apparatus

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 Expansion mechanism part 22b Generator part 22c Sealed container 22d Lubricating oil reservoir 23 Oil equalizing pipe 23a Oil equalizing pipe for compressor 23b Oil equalizing pipe for expander 24 Pressure equalizing pipe 24a Pressure equalizing pipe for compressor 24b Pressure equalizing pipe for expander 25 Lubricating oil separator 26 Lubricating oil return pipe 27 Fixing member 28 Reject

Claims (5)

A compressor composed of a compression mechanism section and a sealed container for storing an electric motor section; a radiator for cooling the refrigerant compressed by the compressor; a sealed container for storing an expansion mechanism section and a generator section; A refrigeration cycle apparatus comprising: an expander configured by: an evaporator for evaporating the refrigerant expanded by the expander; and a refrigerant pipe for circulating the refrigerant between the expander and the lubricating oil for the compressor The compressor and the expander are fixed such that the surface and the lubricating oil surface of the expander are substantially the same surface, and the oil leveling pipe that communicates the positions lower than the lubricating oil surface and the positions higher than the lubricating oil surface communicate A refrigeration cycle apparatus connected with a pressure equalizing pipe. The oil equalizing pipe and the pressure equalizing pipe are divided for the compressor and the expander, which are expanded or contracted so as to form an in-wax at the time of combination, and are welded or brazed to the compressor and the expander, respectively. The refrigeration cycle apparatus according to claim 1, wherein the oil equalizing pipe and the pressure equalizing pipe are hermetically fixed by welding or brazing when the compressor and the expander are fixed. The refrigeration cycle apparatus according to claim 1, wherein the compressor and the expander are fixed to the same leg. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the refrigerant is carbon dioxide which is a high-pressure refrigerant. The refrigeration cycle apparatus according to claim 4, wherein a lubricating oil mainly composed of polyalkylene glycol is used as the lubricating oil.

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