JP2008151405A - Refrigeration cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly efficient refrigeration cycle device maintaining high reliability, capable of realizing a favorable lubrication state of an expander by a simple composition. <P>SOLUTION: A coolant circuit is composed by connecting a compressor housing a compressing mechanism compressing a coolant in a sealed container, a radiator carrying out heat radiation of the coolant compressed by the compressor, the expander housing an expanding mechanism expanding the coolant radiated by the radiator in a sealed container, and an evaporator evaporating the coolant expanded by the expander, by a tubing in sequence. In the refrigeration cycle device, the expander and the compressor are connected by one communication tubing, and lubricating oil levels of a lubricating oil sump in the expander and a lubricating oil sump in the compressor are positioned in the same position in a vertical direction of a connection end of the communication tubing in an expander side and a connection end in a compressor side, between a lower rim and an upper rim of the communication tubing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus including an expander that recovers power energy by expanding a compressive fluid.

  A conventional refrigeration cycle apparatus having an expander is disclosed in Non-Patent Document 1, for example, and the configuration thereof will be described below with reference to FIG.

  FIG. 8 is a configuration diagram of a conventional refrigeration cycle apparatus having a pressure equalizing pipe and an oil equalizing pipe. As shown in FIG. 8, a conventional refrigeration cycle apparatus 900 is configured by connecting a compressor 901, a radiator 902, an expander 903, and an evaporator 904 in order via a pipe 905. . The compressor 901 includes a compression mechanism 908, an electric motor 909, and a sealed container 910 that stores them. The expander 903 includes an expansion mechanism 912, a generator 913, and a sealed container 914 that stores them. The compressor 901 and the expander 903 are connected by a pressure equalizing pipe 906 and an oil equalizing pipe 907.

  Hereinafter, the flow of the refrigerant in the conventional refrigeration cycle apparatus 900 will be described.

  As shown in FIG. 8, the refrigerant is sucked into the compression mechanism 908 and the temperature is increased. Then, after being stored in the space in the compressor 901, it is discharged from the compressor 901. The high-pressure refrigerant discharged from the compressor 901 flows into the radiator 902 and dissipates heat by moving heat to the outside. The high-pressure refrigerant radiated by the radiator 902 flows out of the radiator 902 and is then directly sucked into the expansion mechanism 912 of the expander 903 to expand to a low temperature and low pressure. The low-temperature and low-pressure refrigerant is directly discharged from the expansion mechanism 912, then flows into the evaporator 904, absorbs heat from the outside, flows out of the evaporator 904, and is sucked into the compressor 901 again. As described above, in the conventional refrigeration cycle apparatus 900, the refrigerant circulation is repeatedly performed.

  Next, the flow of lubricating oil in the conventional refrigeration cycle apparatus 900 will be described.

  First, the flow of lubricating oil in the compressor 901 will be described. In the compressor 901, the lubricating oil pumped up from the lubricating oil reservoir 911 by a lubricating oil pump (not shown) is introduced into the compression mechanism 908 through a path provided in the shaft. The lubricating oil introduced into the compression mechanism 908 is discharged into a space in the compressor 901 together with the refrigerant. At this time, most of the lubricating oil is separated from the refrigerant stream and returns to the lubricating oil pool 911.

  Next, the flow of lubricating oil in the expander 903 will be described. In the expander 903, the lubricating oil pumped up from the lubricating oil reservoir 915 by a lubricating oil pump (not shown) is introduced into the expansion mechanism 912 through a path provided in the shaft. The lubricating oil introduced into the expansion mechanism 912 is discharged from the expander 903 together with the refrigerant. At this time, the lubricating oil in the lubricating oil reservoir 915 is also discharged together with the refrigerant, and the lubricating oil in the lubricating oil reservoir 915 gradually decreases as the operating time of the refrigeration cycle apparatus 900 elapses.

In order to prevent this, the conventional refrigeration cycle apparatus 900 is provided with an oil equalizing pipe 907 that connects the lubricating oil reservoir 911 located at the lower portion of the compressor 901 and the lubricating oil reservoir 915 located at the lower portion of the expander 903. is doing. Further, in order to balance the amount of lubricating oil inside the expander 903 and the amount of refrigerant, the conventional refrigeration cycle apparatus 900 is provided with a pressure equalizing pipe 906 connecting the upper part of the compressor 901 and the upper part of the expander 903. Yes.
"Leading research and development of effective energy utilization basic technology Development of two-phase flow expander / compressor for CO2 air conditioner" NEDO (New Energy and Industrial Technology Development Organization)

  In the conventional refrigeration cycle apparatus 900, the lubricating oil reservoirs 911 and 915 and the refrigerant spaces of the compressor 901 and the expander 903 are communicated with each other using independent pressure equalizing pipes 906 and oil equalizing pipes 907, respectively. Here, since the inside of the compressor 901 is filled with the refrigerant discharged from the compression mechanism 908, it is at a high temperature. On the other hand, in the expander 903, an expansion mechanism 912 that sucks and expands the low-temperature refrigerant after passing through the radiator 902 is housed, so that the expander 903 has a low temperature. Therefore, since the refrigerant temperature is different between the compressor 901 and the expander 903, the refrigerant density is also different.

  FIG. 9 shows changes in density with respect to the temperature of carbon dioxide under a constant pressure (10 MPa). When carbon dioxide is used as the refrigerant of the refrigeration cycle apparatus 900, the density change with respect to temperature is large as shown in FIG.

  The head pressure due to the refrigerant existing below each connection position with the pressure equalizing pipe 906 acts on each connection position with the oil equalizing pipe 907 in the compressor 901 and the expander 903. As described above, Therefore, the head pressure acting on the lubricating oil surface of the lubricating oil reservoir 911 in the compressor 901 is different from the head pressure acting on the lubricating oil surface of the lubricating oil reservoir 915 in the expander 903.

For example, the refrigerant temperature / refrigerant pressure in the compressor 901 is 100 ° C. · 10 MPa, and the refrigerant temperature / refrigerant pressure in the expander 903 is 20 ° C. · 10 MPa. In this case, the refrigerant density in the compressor 901 is 188.56 kg / m ³ , and the refrigerant density in the expander 903 is 856.31 kg / m ³ .

  Here, as shown in FIG. 8, the distance between the connection position of the pressure equalizing pipe 906 and the connection position of the oil equalizing pipe 907 in the compressor 901 is H, and the connection position of the oil equalizing pipe 907 from the connection position of the pressure equalizing pipe 906 in the expander 903 is set. Let h be the distance between the connection positions.

The head pressure due to the refrigerant acting on each connection position of the oil equalizing pipe 907 can be calculated by “refrigerant density × the distance from the oil equalizing position to the pressure equalizing position”. In the case of the above example, the head pressure acting on the connection position of the oil leveling pipe 907 on the compressor 901 side is 188.56 × Hkg / m ² , and the head pressure acting on the connection position of the oil leveling pipe 907 on the expander 903 side is 856.31 × hkg / m ² .

  As described above, when there is a difference in the head pressure, the lubricating oil in the sealed container on the side with the larger head pressure moves into the sealed container on the side with the smaller head pressure. As a result, the lubricating oil in the lubricating oil pool in the closed container on the side with the larger head pressure is reduced, so that the lubricating oil supplied to the drive mechanism is also reduced, which may lead to a decrease in reliability.

  In order to suppress the movement of the lubricating oil, the head pressures acting on the connection positions of the oil equalizing pipes 907 in the sealed containers 910 and 914 are equalized, the distance H between the connection positions on the compressor 901 side, and the expander 903 side Must be set to a value satisfying H / h = 856.31 / 188.56.

  Accordingly, if the distance H between the connection positions and the distance h between the connection positions are set so that the head pressures are equal to each other, one condition (in the above example, the refrigerant temperature / refrigerant pressure in the compressor 901 is 100 ° C. Under the pressure of 10 MPa and the refrigerant temperature / refrigerant pressure in the expander 903 is 20 ° C./10 MPa), the head pressure difference disappears and the lubricating oil surfaces of the lubricating oil reservoirs 911 and 915 are balanced, and the lubricating oil reservoir 911, 915 stabilizes.

  However, since the refrigeration cycle apparatus 900 is operated under a plurality of operating conditions, the lubricating oil surfaces of the lubricating oil reservoirs 911 and 915 cannot always keep the balance, and eventually the compressor is caused by the occurrence of a head pressure difference. An imbalance occurs between the lubricating oil surfaces of the lubricating oil reservoirs 911 and 915 in the 901 and the expander 903.

  The present invention solves such problems, and an object of the present invention is to provide a highly reliable and highly efficient refrigeration cycle apparatus that enables appropriate lubricating oil management.

  The expander of the present invention includes a compressor in which a compression mechanism for compressing a refrigerant is housed in an airtight container, a radiator for radiating the refrigerant compressed by the compressor, and an expansion mechanism for expanding the refrigerant radiated by the radiator. In a refrigerant circuit configured by sequentially connecting an expander housed in an airtight container and an evaporator for evaporating the refrigerant expanded in the expander with a pipe, the expander and the compressor are connected to each other. Connected by piping, the connecting end on the expander side and the connecting end on the compressor side of the connecting pipe have the same position in the vertical direction, and the lubricating oil reservoir in the expander and the lubricating oil reservoir in the compressor The lubricating oil surface is positioned between the lower edge and the upper edge of the connecting pipe.

  As a result, pressure can be equalized at the same height with respect to the lubricating oil surface of each lubricating oil reservoir in the compressor and expander, and the lubricating oil in each lubricating oil reservoir is not affected by the head pressure due to the refrigerant. For this reason, the lubricating oil surfaces of the respective lubricating oil reservoirs in the compressor and the expander can always be balanced on the same surface, and appropriate lubricating oil management becomes possible. In addition, since the number of pipes to be used can be reduced as compared with the prior art, the cost for producing the refrigeration cycle apparatus can be reduced.

  In the expander of the present invention, one end of the communication pipe is connected to a position above the generator pump of the expander and above the lubricating oil pump, and the other end is located below the electric motor section of the compressor and above the lubricating oil pump. It is connected.

  Thereby, the lubricating oil surface of each lubricating oil pool can be ensured above the suction port of each lubricating oil pump. In addition, the lubricant in the lubricating oil reservoir in the expander is prevented from becoming foamed with the refrigerant by stirring the refrigerant and the lubricating oil under the influence of the swirling flow caused by the rotation of the shaft of the generator unit. The lubricating oil surface of the lubricating oil reservoir can be kept stable. Similarly, the lubricating oil in the lubricating oil pool in the compressor can also stably maintain the lubricating oil surface of the lubricating oil pool without being affected by the swirling flow caused by the rotation of the shaft of the motor unit. Therefore, by maintaining the fluid in the communication pipe in two stable layers of the refrigerant and the lubricating oil, only the lubricating oil can be reliably introduced into the suction port of each lubricating oil pump.

  In the expander of the present invention, the connecting pipe is provided horizontally between the connection end on the expander side and the connection end on the compressor side.

  As a result, the lubricating oil does not stagnate in the connecting pipe, and the lubricating oil moves between the expander and the compressor. The amount of lubricating oil in the lubricating oil pool in the expander is the amount required for lubrication. High reliability can be ensured without falling below.

  In the expander of the present invention, at least one valve is provided in the communication pipe.

  As a result, when the refrigeration cycle is started or the like, in an operation state where the discharge of the lubricating oil from the compressor is large, the lubricating oil moves from the lubricating oil reservoir in the expander to the compressor by closing the valve provided in the communication pipe. Can be prevented.

  In the expander of the present invention, in the cross-sectional shape of the communication pipe, the vertical dimension is larger than the horizontal dimension.

  As a result, even if the amount of lubricating oil discharged in the compressor and expander increases due to changes in the operating conditions of the refrigeration cycle device, and the lubricating oil level of each lubricating oil reservoir decreases, the connecting pipe and each lubricating oil reservoir are lubricated. Sufficient oil can be secured, and the balance of the lubricating oil surface of each lubricating oil reservoir can be maintained. In addition, even if the lubricating oil discharged from the compressor adheres to the piping and heat exchanger of the refrigeration cycle device and the lubricating oil level of each lubricating oil pool in the compressor and expander decreases, the same as above The effect of can be obtained.

  In the expander of the present invention, in the cross-sectional shape of the connecting pipe, the distance between the position in the vertical direction of the cross section where the dimension in the horizontal direction is maximum and the lower limit of the lower edge of the cross section It is smaller than the distance.

  As a result, the cross-sectional area of the lower part of the connecting pipe having a two-layer flow area, that is, the lubricating oil flow area in the connecting pipe can be increased, and the resistance due to the viscosity of the lubricating oil moving in the connecting pipe can be reduced. , Free movement of lubricating oil can be realized. In addition, the cross-sectional area of the upper part of the communication pipe, that is, the refrigerant flow area in the communication pipe can be reduced, and a refrigerant flow path necessary for pressure transmission is ensured at the minimum, and the refrigerant moves more than necessary. Heat transfer can be reduced.

  The expander of this invention has a means to isolate | separate a refrigerant | coolant and lubricating oil in the inner wall of the connection port with the connection piping provided in the said compressor.

  As a result, the high-temperature lubricating oil droplets scattered in the refrigerant in the compressor can remain in the compressor without moving to the communication pipe or the expander, and the compressor Heat loss can be suppressed.

  In the expander of the present invention, the connecting pipe is provided with a heat insulating means.

  As a result, a temperature drop in the compressor due to heat transfer through a connecting pipe connecting a compressor that becomes high temperature during the refrigeration cycle operation and an expander that becomes low temperature compared to the compressor, and the compressor accompanying it The temperature drop of the refrigerant discharged from the can be prevented.

  As described above, according to the present invention, pressure can be equalized at the same height with respect to the lubricating oil surface of each lubricating oil reservoir in the compressor and the expander, and the lubricating oil in each lubricating oil reservoir is a head made of a refrigerant. It is not affected by pressure. For this reason, the lubricating oil surfaces of the lubricating oil reservoirs in the compressor and the expander can always be balanced on the same surface, enabling appropriate management of the lubricating oil, achieving high reliability and high efficiency. It is possible to provide a simple refrigeration cycle apparatus.

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

(Embodiment 1)
FIG. 1 is a configuration diagram of a refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention. As shown in FIG. 1, the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention includes a compressor 101, a radiator 102, an expander 103, and an evaporator 104 connected in order via a pipe 105. It is configured. The compressor 101 and the expander 103 are connected by a communication pipe 106 provided with a valve 107.

  As for the installation range of the connecting pipe 106, one end of the connecting pipe 106 is positioned below the bottom surface of the electric motor 108 of the compressor 101 and above the top surface of the lubricating oil pump 109, and the other end is positioned below the bottom surface of the generator 110 of the expander 103. The position is above the upper surface of the lubricating oil pump 111. Further, by providing a valve 107 in the communication pipe 106, the refrigerant flow rate and the lubricating oil flow rate are adjusted.

  FIG. 2 is a cross-sectional view of communication pipe 106 in Embodiment 1 of the present invention. As shown in FIGS. 1 and 2, the connecting pipe 106 in Embodiment 1 of the present invention has a single linear shape, and a long side whose left and right surfaces are formed by vertical straight lines, and upper and lower The surface is composed of a short side constituted by an arc. Further, in the communication pipe 106, there are two-layer flow areas where the upper part is a refrigerant flow area 106a and the lower part is a lubricating oil flow area 106b, and a pressure equalizing pipe 906 and an oil equalizing pipe 907 in the conventional refrigeration cycle apparatus 900 are provided. It has become a form that is integrated.

  FIG. 3 is a diagram showing a positional relationship of the communication pipe 106 in the first embodiment of the present invention. As shown in FIG. 3, the connecting pipe 106 is connected to the compressor 101 and the expander 103 so as to satisfy the positional relationship that one connection port upper edge upper limit 106 c is above the other connection port lower edge lower limit 106 d. Has been. In addition, as long as the connection port upper edge upper limit 106c and the connection port lower edge lower limit 106d are on the compressor 101 side or the expander 103 side, as long as they are connected so as to satisfy the positional relationship, However, the same effect can be obtained. Further, even if the connecting pipe 106 is inclined, there is no problem in configuration as long as it is in a range that satisfies the above positional relationship.

  The initial amount of lubricating oil in the compressor 101 and the expander 103 is determined so that each lubricating oil surface has an upper upper limit 106c on one connection port and a lower lower limit 106d on the other connection port in the communication pipe 106 when the refrigeration cycle apparatus 100 is stopped. It is enclosed so that it may be located between.

  Hereinafter, the flow of the refrigerant in the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described.

  As shown in FIG. 1, the refrigerant is sucked into the compression mechanism 113 and the temperature is increased. Then, after being stored in the space in the compressor 101, it is discharged from the compressor 101. The high-pressure refrigerant discharged from the compressor 101 flows into the radiator 102 and dissipates heat by moving heat to the outside. The high-pressure refrigerant radiated by the radiator 102 flows out of the radiator 102 and then directly sucked into the expansion mechanism 116 of the expander 103 to expand to a low temperature and low pressure. The low-temperature and low-pressure refrigerant is directly discharged from the expansion mechanism 116, then flows into the evaporator 104, absorbs heat from the outside, flows out of the evaporator 104, and is sucked into the compressor 101 again. As described above, in the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention, the refrigerant circulation is repeatedly performed.

  Next, the flow of the lubricating oil in the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described.

  First, the flow of lubricating oil in the compressor 101 will be described. In the compressor 101, the lubricating oil pumped up from the lubricating oil reservoir 112 by the lubricating oil pump 109 is introduced into the compression mechanism 113 through a path provided in the shaft. The lubricating oil introduced into the compression mechanism 113 is discharged into the space 114 in the compressor 101 together with the refrigerant. At this time, most of the lubricating oil is separated from the refrigerant stream and returns to the lubricating oil reservoir 112.

  Next, the flow of lubricating oil in the expander 103 will be described. In the expander 103, the lubricating oil pumped up by the lubricating oil pump 111 from the lubricating oil reservoir 115 is introduced into the expansion mechanism 116 through a path provided in the shaft. The lubricating oil introduced into the expansion mechanism 116 is discharged from the expander 103 together with the refrigerant. At this time, the lubricating oil in the lubricating oil reservoir 115 is also discharged together with the refrigerant, and the lubricating oil in the lubricating oil reservoir 115 gradually decreases as the operating time of the refrigeration cycle apparatus 100 elapses.

  However, in the first embodiment of the present invention, the use of the communication pipe 106 can suppress the reduction of the lubricating oil in the lubricating oil reservoir 115.

  As described above, in the communication pipe 106 according to the first embodiment of the present invention, the upper part is the refrigerant flow area 106 a and the lower part is the lubricating oil flow area 106 b, and there are two layers of flow areas in the communication pipe 106. is doing. As described above, the two layers of the refrigerant and the lubricating oil exist in one communication pipe 106, so that the pressure equalized by the refrigerant in the compressor 101 and the expander 103 and the lubricating oil reservoirs 112 and 115 are obtained. The height of each lubricating oil surface is equal. In other words, the distance between the oil leveling position and the pressure leveling position in the expression “refrigerant density × the distance between the oil leveling position and the pressure equalizing position” for determining the head pressure by the refrigerant becomes 0, and the compressor 101 and the expander Even if the refrigerant densities in 103 are different, there is no difference in head pressure acting on the lubricating oil in the lubricating oil reservoirs 112 and 115.

  As a result, there is no imbalance in the lubricating oil surfaces in the lubricating oil reservoirs 112 and 115 in the compressor 101 and the expander 103, and the lubricating oil is stably secured in the compressor 101 and the expander 103. And a good lubrication state can be maintained.

  In addition, one end of the connecting pipe 106 in Embodiment 1 of the present invention is connected to a position below the bottom surface of the motor 108 of the compressor 101 to a position above the top surface of the lubricating oil pump 109, and the other end is a generator of the expander 103. It is connected to a position above the bottom surface of 110 and above the top surface of the lubricating oil pump 111.

  Thereby, in the compressor 101 and the expander 103, it is possible to secure the lubricating oil surfaces of the lubricating oil reservoirs 112 and 115 above the respective suction ports of the lubricating oil pumps 109 and 111. In addition, the lubricating oil in the lubricating oil reservoir 115 in the expander 103 is agitated with the refrigerant under the influence of the swirling flow caused by the rotation of the shaft of the generator 110, thereby preventing foaming involving the refrigerant. The lubricating oil surface of the lubricating oil reservoir 115 can be kept stable. Similarly, the lubricating oil in the lubricating oil reservoir 112 in the compressor 101 can also stably maintain the lubricating oil surface of the lubricating oil reservoir 112 without being affected by the swirling flow caused by the rotation of the shaft of the electric motor 108. Therefore, by maintaining the fluid in the communication pipe 106 in two stable layers of the refrigerant and the lubricating oil, the lubricating oil can be reliably supplied to the suction ports of the lubricating oil pumps 109 and 111 in the compressor 101 and the expander 103. Can only be introduced.

  Further, in the first embodiment of the present invention, the connecting pipe 106 has a single linear shape, and one upper connection port upper edge upper limit 106c of the connecting pipe 106 is disposed above the other lower connecting port lower edge lower limit 106d. Therefore, the lubricating oil can always keep a continuous oil level in the connecting pipe 106, and the lubricating oil can be prevented from stagnating in the connecting pipe 106.

  Generally, the refrigeration cycle apparatus is operated under a plurality of operating conditions. When changing from a certain operating condition to a different operating condition, the shaft rotation speeds of the compressor and the expander also change. For this reason, the amount of lubricating oil pumped up from the lubricating oil reservoir in the compressor and the amount of lubricating oil pumped up from the lubricating oil reservoir in the expander change, and the position where the lubricating oil surface of each lubricating oil reservoir keeps balance also changes.

  Even in such a case, as shown in FIG. 3, the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention has the left and right surfaces of the connecting pipe 106 as long sides constituted by vertical straight lines. Even if the height of each lubricating oil surface of the lubricating oil reservoirs 112 and 115 changes, a sufficient amount of lubricating oil can be secured in the communication pipe 106 and the lubricating oil reservoirs 112 and 115, and each of the lubricating oil reservoirs 112 and 115 can be secured. The balance of the lubricating oil surface can be maintained.

  In general, when the refrigeration cycle apparatus is started, the lubricating oil level of each of the remaining lubricating oil pools is greatly lowered due to sudden pumping of the lubricating oil caused by starting the compressor and the expander. In the refrigeration cycle apparatus, since the compressor is larger than the expander, the pumping capacity of the lubricating oil pump in the compressor is large. Therefore, at the time of start-up, the lubricating oil in the lubricating oil reservoir in the compressor is quickly reduced, and in some cases, the lubricating oil pump in the compressor may pump up to the lubricating oil in the lubricating oil reservoir in the expander. Excessive pumping of the lubricating oil by the lubricating oil pump in the compressor may reduce the lubricating oil in the lubricating oil pool in the expander and may not maintain the amount of lubricating oil necessary for lubricating the expander.

  Even in such a case, the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention provides the valve 107 in the connecting pipe 106 as shown in FIG. The lubricating oil pump 109 in the compressor 101 can be prevented from pumping up the lubricating oil in the lubricating oil reservoir 115 in the expander 103, and sufficient lubricating oil in the expander 103 can be secured.

(Embodiment 2)
FIG. 4 is a configuration diagram of the refrigeration cycle apparatus 200 according to Embodiment 2 of the present invention. As shown in FIG. 4, the refrigeration cycle apparatus 200 according to Embodiment 2 of the present invention includes a compressor 201, a radiator 202, an expander 203, and an evaporator 204 connected in order via a pipe 205. It is configured. Further, the compressor 201 and the expander 203 are connected by a communication pipe 206 provided with a valve 207 and a heat insulating means 217. Lubricating oil separating means 218 is provided on the inner wall of the connection port with the connecting pipe 206 provided in the compressor 201.

  Note that the installation range of the connecting pipe 206, the role of the valve 207, the flow of the refrigerant and the lubricating oil in the refrigeration cycle apparatus 200 according to the second embodiment of the present invention are the same as those in the refrigeration cycle apparatus according to the first embodiment. Is omitted.

  FIG. 5 is a cross-sectional view of the connecting pipe 206 according to Embodiment 2 of the present invention. As shown in FIGS. 4 and 5, the connecting pipe 206 according to the second embodiment of the present invention has a single linear shape, and a long side whose left and right surfaces are formed by vertical straight lines, and upper and lower The surface consists of a short side constituted by an arc. Further, the upper arc surface of the communication pipe 206 has a smaller diameter than the lower arc surface, and the cross-sectional shape thereof is substantially a drop shape. Further, in the communication pipe 206, there are two-layer flow areas, the refrigerant flow area 206a at the top and the lubricant flow area 206b at the bottom, and the pressure equalizing pipe 906 and oil equalizing pipe 907 in the conventional refrigeration cycle apparatus 900 are provided. It has become a form that is integrated.

  In order to equalize the pressure in the compressor and in the expander, it is necessary to connect each refrigerant space, but if the refrigerant space to be communicated is enlarged, the influence of mixing of the high-temperature refrigerant in the compressor and the low-temperature refrigerant in the expander, or The influence of heat conduction from the high-temperature refrigerant in the compressor to the low-temperature refrigerant in the expander increases, and the high-temperature refrigerant in the compressor loses heat, and the refrigerant temperature discharged from the compressor decreases.

  However, the communication pipe 206 according to the second embodiment of the present invention can narrow the refrigerant flow region 206a in the communication pipe 206 by making the upper arc surface smaller in diameter than the lower arc surface. That is, by narrowing the refrigerant communication space, the heat transfer from the compressor 201 to the expander 203 can be suppressed, and the temperature drop of the refrigerant discharged from the compressor 201 can be reduced.

  In addition, the connecting pipe 206 according to the second embodiment of the present invention can widen the lubricating oil flow region 206b in the connecting pipe 206 by making the lower arc surface larger in diameter than the upper arc surface. That is, by widening the lubricating oil flow region 206b in the connecting pipe 206, the lubricating oil can be smoothly moved between the compressor 201 and the expander 203, and the lubricating oil surface can be quickly balanced. Therefore, when the oil in the compressor 201 and the expander 203 is leveled, the larger the connecting pipe 206 is, the smaller the influence of friction between the lubricating oil and the inner wall of the connecting pipe 206 is, so that the lubricating oil receives a large resistance. It is possible to move smoothly through the connecting pipe 206 without any problems.

  Note that the cross-sectional shape of the connecting pipe 206 in Embodiment 2 of the present invention is not limited to the above, and if the refrigerant flow area 206a in the connecting pipe 206 is narrow and the lubricating oil flow area 206b is wide, for example, Similar effects can be obtained even in a shape in which the cross-sectional area changes discontinuously as shown in FIGS. FIG. 6 (a) shows a convex cross-sectional shape of the connecting pipe 206 according to the second embodiment of the present invention that forms a step at a certain position, and FIG. 6 (b) illustrates the implementation of the present invention. The cross-sectional shape of the connection pipe 206 in the form 2 is shown in which large and small circles are overlapped.

  As shown in FIG. 4, the connecting pipe 206 in the second embodiment of the present invention is provided with a heat insulating means 217. The heat insulating means 217 is provided with a pipe connecting portion made of a material having low thermal conductivity.

  Accordingly, the heat transfer from the high-temperature compressor 201 to the low-temperature expander 203 is prevented by heat conduction through the communication passage 206, thereby reducing the temperature of the refrigerant in the compressor 201 and discharging from the compressor 201. It is possible to prevent the temperature of the refrigerant to be lowered.

  A high-temperature refrigerant exists in the vicinity of the inner wall of the connection port with the connection pipe 206 provided in the compressor 201, and lubricating oil droplets that have not returned to the lubricating oil reservoir 212 are floating in the refrigerant. When this high-temperature refrigerant moves to the connecting pipe 206, oil droplets may also move to the connecting pipe 206 along the refrigerant flow. At the same time, the heat of the high-temperature oil droplets moves to the refrigerant and lubricating oil in the expansion pipe 203 that communicates with the communication pipe 206, thereby releasing the heat in the compressor 201. The temperature of the refrigerant discharged from the refrigerant may decrease.

  However, in Embodiment 2 of the present invention, the lubricating oil separating means 218 is provided on the inner wall of the connection port with the connecting pipe 206 provided in the compressor 201, so that the temperature from the compressor 201 to the connecting pipe 206 is high. When the refrigerant moves, the lubricating oil droplets floating in the refrigerant can be retained in the compressor 201, and the heat loss of the compressor 201 can be suppressed. FIG. 7 (a) is a perspective view of the lubricating oil separating means 218 in Embodiment 2 of the present invention, and FIG. 7 (b) is a front view of (a). As shown in FIGS. 7A and 7B, the lubricating oil separating means 218 according to Embodiment 2 of the present invention is configured by arranging a plurality of thin plates 218a having a large number of pores with gaps therebetween. ing.

  The lubricating oil separating means 218 in Embodiment 2 of the present invention is not limited to the above, and the same effect can be obtained by using, for example, a metal mesh.

  Note that the refrigeration cycle apparatus according to Embodiments 1 and 2 of the present invention has been described as an apparatus in which the flow direction of the refrigerant is constant, but is not limited to the above, for example, reversible that can change the flow direction of the refrigerant. A refrigerating cycle apparatus or the like that can be operated may be used, and can be used as a water heater, an air conditioner, or the like.

  Further, the expander according to the first and second embodiments of the present invention is not limited to the above, and various other configurations are possible.

  The present invention is useful for a refrigeration cycle apparatus including an expander that recovers power energy by expanding a compressive fluid.

Configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. Sectional drawing of the connection piping which concerns on Embodiment 1 of this invention The figure which shows the positional relationship of the connection piping which concerns on Embodiment 1 of this invention. Configuration diagram of a refrigeration cycle apparatus according to Embodiment 2 of the present invention Sectional drawing of the connection piping which concerns on Embodiment 2 of this invention (A) Cross-sectional view of a connecting pipe whose cross section changes discontinuously according to Embodiment 2 of the present invention (b) Cross-sectional view of a connecting pipe whose cross section changes discontinuously according to Embodiment 2 of the present invention (A) Perspective view of lubricating oil separating means according to Embodiment 2 of the present invention (b) Front view of (a) above Schematic diagram of a conventional refrigeration cycle system with pressure equalizing and oil equalizing pipe Carbon dioxide temperature-density diagram

Explanation of symbols

100, 200, 900 Refrigeration cycle apparatus 101, 201, 901 Compressor 102, 202, 902 Radiator 103, 203, 903 Expander 104, 204, 904 Evaporator 105, 205, 905 Piping 106, 206 Connecting piping 106a, 206a Refrigerant flow region 106b, 206b Lubricant oil flow region 106c Upper limit of connection port upper edge 106d Lower limit of connection port lower edge 107, 207 Valve 108, 208, 909 Electric motor 109, 209 Compressor lubricant oil pump 110, 210, 913 Generator 111, 211 Lubricating oil pump 112, 212, 911 Compressor lubricating oil reservoir 113, 213, 908 Compressor mechanism 114, 214 Space 115, 215, 915 Expander lubricating oil reservoir 116, 216, 912 Expansion mechanism 117, 118, 219, 220, 910, 14 sealed container 217 insulating means 218 lubricating oil separating means 218a sheet 906 pressure equalizing pipe 907 having a large number of pores equalizing pipe

Claims (8)

A compressor in which a compression mechanism for compressing refrigerant is housed in a sealed container, a radiator for dissipating heat from the refrigerant compressed by the compressor, and an expansion machine in which an expansion mechanism for expanding the refrigerant radiated by the heat radiator is housed in a sealed container. And an evaporator that evaporates the refrigerant expanded in the expander in order by a pipe,
The expander and the compressor are connected by a single connection pipe,
The position in the vertical direction of the connecting end on the expander side and the connecting end on the compressor side of the communication pipe are the same,
When the operation of the compressor was stopped, the lubricating oil surface of the lubricating oil reservoir in the expander and the lubricating oil surface of the lubricating oil reservoir in the compressor were positioned between the lower edge and the upper edge of the communication pipe. , Refrigeration cycle equipment. One end of the connecting pipe is connected to a position above the lubricating oil pump from the generator section of the expander, and the other end is connected to a position above the lubricating oil pump from the motor section of the compressor.
The refrigeration cycle apparatus according to claim 1. The connecting pipe is provided horizontally between the connecting end on the expander side and the connecting end on the compressor side,
The refrigeration cycle apparatus according to claim 1. At least one valve is provided in the communication pipe;
The refrigeration cycle apparatus according to claim 1. In the cross-sectional shape of the connecting pipe, the vertical dimension is larger than the horizontal dimension.
The refrigeration cycle apparatus according to any one of claims 1 to 4. In the cross-sectional shape of the connecting pipe, the distance between the position in the vertical direction of the cross section where the dimension in the horizontal direction is maximum and the lower limit of the lower edge of the cross section is smaller than the distance between the position in the vertical direction of the cross section and the upper limit of the upper edge of the cross section.
The refrigeration cycle apparatus according to any one of claims 1 to 4. Means for separating the refrigerant and the lubricating oil on the inner wall of the connection port with the connecting pipe provided in the compressor;
The refrigeration cycle apparatus according to any one of claims 1 to 4. Insulating means was provided in the connecting pipe,
The refrigeration cycle apparatus according to any one of claims 1 to 4.

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