JP2007263432A - Refrigerant cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat exchanging capacity by smoothly discharging oil stored in an evaporator, and to solve shortage of oil in a compressor of the refrigerant cycle device comprising the evaporator. <P>SOLUTION: In this refrigerant cycle device 1 having a refrigerant cycle composed of the compressor 10, a radiator 154, an expansion valve 156 (pressure reducing device) and the evaporator 157, the refrigerant flows in from an upper portion of the evaporator 157, and the refrigerant flows out from a lower portion of the evaporator 157. Thus the oil flowing into the evaporator 157 can flow downward. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigerant cycle device in which a refrigerant cycle is constituted by a compressor, a radiator, a decompression device, an evaporator, and the like.

Conventionally, this type of refrigerant cycle apparatus is configured by connecting a compressor, a radiator, a decompression device such as an expansion valve and a capillary tube, an evaporator, and the like sequentially in a circular pipe connection. Then, the refrigerant gas compressed by the compressor dissipates heat by the radiator and is depressurized by the decompressor, and then evaporates by exchanging heat with the surroundings by the evaporator. At this time, the refrigerant exhibited a cooling action by absorbing heat from the surroundings (for example, Patent Document 1).
Japanese Patent Publication No. 7-18602

  In such a refrigerant cycle device, the oil discharged from the compressor accumulates in the refrigerant path of a heat exchanger such as a radiator or an evaporator, and the oil causes a disadvantage that the heat exchange performance in the heat exchanger is changed. It was. In particular, the conventional evaporator has a specification in which a refrigerant inlet is formed in the lower part of the evaporator and a refrigerant outlet is formed in the upper part so that the refrigerant and oil that have flowed into the evaporator flow from the bottom to the top. Was very difficult to flow. As a result, the flow rate of the refrigerant flowing through the refrigerant passage of the evaporator is slowed, resulting in a problem that the heat exchange performance is deteriorated. Furthermore, since the oil accumulated in the evaporator does not return to the compressor, the amount of oil in the compressor is insufficient and the sliding performance is deteriorated.

  In recent years, in this type of refrigerant cycle device, an attempt has been made to use carbon dioxide, which is a natural refrigerant, as a refrigerant. However, since the carbon dioxide refrigerant has a slower flow rate than other refrigerants, other refrigerants are used. The deterioration of heat exchange performance has become a more serious problem due to the oil reservoir in the evaporator described above than the refrigerant cycle apparatus used.

  The present invention has been made to solve the conventional technical problems, and smoothly drains the oil accumulated in the evaporator to improve the heat exchanging ability and includes the evaporator. It aims at solving the oil shortage of the compressor of a refrigerant cycle device.

  The refrigerant cycle device of the present invention is configured by a refrigerant cycle including a compressor, a radiator, a decompression device, an evaporator, and the like. The refrigerant is allowed to flow in from the upper part of the evaporator, and the refrigerant is discharged from the lower part of the evaporator. It is characterized by making it.

  A refrigerant cycle device according to a second aspect of the present invention is characterized in that a predetermined amount of carbon dioxide is sealed as a refrigerant in the above invention.

  According to the present invention, in the refrigerant cycle device in which the refrigerant cycle is configured from a compressor, a radiator, a decompression device, an evaporator, and the like, the refrigerant flows in from the upper part of the evaporator, and the refrigerant flows out from the lower part of the evaporator. The oil that has flowed into the evaporator can flow from top to bottom. Thereby, oil can be made to flow down by gravity and the oil which is going to accumulate in an evaporator can be made easy to flow.

  As a result, oil can be smoothly discharged from the evaporator, so that the heat exchange capability of the evaporator can be improved. Further, since the oil discharged from the evaporator returns to the compressor, the shortage of oil in the compressor can be solved.

  In particular, by applying each of the above inventions to a refrigerant cycle device in which a predetermined amount of carbon dioxide refrigerant having a large high-low pressure difference is sealed as in the invention of claim 2, the disadvantage that the heat exchange performance in the evaporator is remarkably deteriorated is eliminated. Thus, the performance of the refrigerant cycle device using the carbon dioxide refrigerant can be improved.

  The present invention improves the inconvenience of the oil flowing out from the compressor being accumulated in the evaporator and hindering the smooth heat exchange of the refrigerant in the evaporator, and eliminating the deterioration of the slidability due to the lack of oil in the compressor. It was made for. The purpose of eliminating the stagnation of oil in the evaporator of the refrigerant cycle device and the shortage of oil in the compressor was realized by flowing the refrigerant from the upper part of the evaporator and flowing the refrigerant from the lower part of the evaporator.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a refrigerant circuit diagram of a refrigerant cycle device according to an embodiment of the present invention. In the refrigerant cycle apparatus 1 of FIG. 1, a compressor 10, a radiator 154, an expansion valve 156 as a decompression device, an evaporator 157, and the like are sequentially connected in an annular manner to form a predetermined refrigerant circuit. A predetermined amount of carbon dioxide (CO ₂ ) is sealed as a refrigerant in the refrigerant circuit. The compressor 10 of the embodiment includes an electric element 14 as a driving element in a sealed container 12, a first rotary compression element 32 and a second rotary compression element 34 that are driven by a rotary shaft 16 of the electric element 14. Is an internal intermediate pressure type multi-stage (two-stage) compression rotary compressor. Then, the refrigerant (CO ₂ ) sucked from the refrigerant introduction pipe 94 is compressed by the first rotary compression element 32, and after the compressed intermediate pressure refrigerant gas is discharged into the sealed container 12, the refrigerant is introduced through the refrigerant introduction pipe 92. Thus, the second rotary compression element 34 is sucked and compressed, and discharged to the refrigerant introduction pipe 96.

  The refrigerant introduction pipe 94 is a refrigerant pipe for introducing refrigerant into the first rotary compression element 32 of the compressor, and one end of the refrigerant introduction pipe 94 is connected to the suction side of the first rotary compression element 32; The other end is connected to the refrigerant outlet 157B of the evaporator 157.

  The refrigerant discharge pipe 96 is a refrigerant pipe for discharging the refrigerant compressed by the second rotary compression element 34 to the radiator 154, and one end of the refrigerant discharge pipe 96 is on the discharge side of the second rotary compression element 34. And the other end is connected to the inlet of the radiator 154.

  The refrigerant introduction pipe 92 is a refrigerant pipe connecting the inside of the sealed container 12 and the suction side of the second rotary compression element 34, and this refrigerant introduction pipe 92 passes through the radiator 154 outside the compressor 10. It is arranged. That is, the intermediate-pressure refrigerant compressed by the first rotary compression element 32 of the compressor 10 and discharged into the sealed container 12 flows into the refrigerant introduction pipe 92 and passes through the radiator 154 in the process of passing through the fan 111. After being radiated and receiving heat, the second rotary compression element 34 is sucked.

  An oil sump is formed at the inner bottom of the sealed container 12 of the compressor 10, and the oil stored in the oil sump is first and second by an oil pump (not shown) attached to the lower end of the rotating shaft 16. 2 is supplied to the sliding portions of the rotary compression elements 32 and 34 to perform lubrication and sealing. In this embodiment, since carbon dioxide having a large difference in high and low pressure is used as the refrigerant, oil having higher viscosity than oil used in the conventional HFC refrigerant is used in consideration of durability. For example, in this embodiment, PAG (polyalkyl glycol) having a viscosity of + 60 ° C. or more at + 40 ° C. is used. In addition, the oil used for the refrigerant cycle apparatus 1 of the embodiment is not limited to the PAG, and may be other high viscosity oil. The high-viscosity oil used here has a pour point of −40 ° C. or higher and a viscosity of 40 to 120 cst at + 40 ° C., preferably an oil having a viscosity of 60 to 80 cst at + 40 ° C. I will use it.

  On the other hand, the outlet of the radiator 154 is connected to a refrigerant pipe reaching the expansion valve 156 as a decompression device. In the refrigerant cycle device 1 of the present embodiment, an expansion valve is used as the pressure reducing device. However, any other device can be used as long as it can depressurize the refrigerant, such as a capillary tube. It doesn't matter.

  On the other hand, the pipe 156A connected to the outlet of the expansion valve 156 is connected to the refrigerant inlet 157A of the evaporator 157, and the refrigerant outlet 157B of the evaporator 157 is connected to the refrigerant introduction pipe 94.

  Here, the evaporator 157 will be described with reference to a front view of the evaporator 157 shown in FIG. The evaporator 157 of the present embodiment is a so-called fin-and-tube heat exchanger, and is a pair of tube plates 121 and 121 and a plurality of aluminum plates disposed at predetermined intervals between the tube plates 121 and 121. The heat exchange fins 122 are made of thin plates, and the refrigerant pipes 101 pass through the tube plates 121 and 121 and the fins 122, respectively. The refrigerant pipe 101 extends in a meandering manner between the tube plates 121 and 121 from the refrigerant inlet 157A formed at the upper end of the evaporator 157 to the refrigerant outlet 157B formed at the lower end of the other end of the evaporator 157. It is arranged. Thus, in the evaporator 157, the refrigerant flows in from the refrigerant inlet 157A formed in the upper part, passes through the meandering passage formed between the tube plates 121 and 121, and then formed in the lower part of the refrigerant outlet 157B. From the evaporator 157.

  Since the refrigerant flows in from the upper part of the evaporator 157 and flows out from the lower part of the evaporator 157 in this way, the refrigerant pipe 101 is arranged in the evaporator 157 from the upper side to the lower side. The oil that has flowed into the refrigerant pipe 101 of the vessel 157 can flow from the top to the bottom. As a result, oil that tends to accumulate in the refrigerant pipe 101 easily flows out of the evaporator 157.

  Next, the operation of the refrigerant cycle device 1 of the present invention will be described with the above configuration. When the electric element 14 of the compressor 10 is energized from a control device (not shown), the electric element 14 is activated. As a result, the low-temperature and low-pressure refrigerant gas is sucked into the first rotary compression element 32 of the compressor 10 and compressed, becomes an intermediate pressure, and is discharged into the sealed container 12. The intermediate-pressure refrigerant gas discharged into the hermetic container 12 enters the refrigerant introduction pipe 92 and radiates heat by the fan 111 of the radiator 154 in an air-cooling manner while the refrigerant introduction pipe 92 passes through the radiator 154.

  Then, the intermediate-pressure refrigerant gas cooled by exchanging heat with air is sucked into the second rotary compression element 34 from the refrigerant introduction pipe 92 and is compressed in the second stage to become a high-temperature and high-pressure refrigerant gas. It is discharged from the discharge pipe 96 to the outside of the compressor 10. At this time, as will be described later, oil supplied to the sliding portion of the second rotary compression element 34 is also discharged together with the refrigerant gas. Refrigerant gas and oil discharged from the compressor 10 flow into the radiator 154 from the refrigerant discharge pipe 96, where they are radiated by the fan 111 in an air-cooling manner, and then discharged from the radiator 154 and decompressed by the expansion valve 156. Then, the refrigerant flows into the refrigerant pipe 101 of the evaporator 157 from the refrigerant inlet 157A formed at the upper part of one end of the evaporator 157 via the pipe 156A.

  Then, the refrigerant that has flowed into the evaporator 157 evaporates in the process of meandering downward in the refrigerant path in the refrigerant pipe 101 and exhibits a cooling action by absorbing heat from the air. Thus, the refrigerant evaporated in the process of passing through the refrigerant pipe 101 of the evaporator 157 then exits from the refrigerant outlet 157B formed at the lower part of the other end of the evaporator 157 and enters the refrigerant introduction pipe 94 to enter the refrigerant 10 The cycle of being sucked into one rotary compression element 32 is repeated.

  Here, oil is supplied to the sliding portions of the first and second rotary compression elements 32 and 34 of the compressor 10, and the oil supplied to the rotary compression elements 32 and 34 in relation to lubrication and sealing. Is discharged to the outside of the compressor 10, but the oil may accumulate in a heat exchanger such as the radiator 154 or the evaporator 157 in the refrigerant path. In particular, in the evaporator 157 where the temperature is low, the oil in the refrigerant pipe 101 has a low viscosity, and the oil tends to accumulate.

  Furthermore, since the evaporator normally flows while evaporating the refrigerant, the conventional evaporator has a refrigerant inlet formed in the lower part of the evaporator and a refrigerant outlet formed in the upper part. That is, the refrigerant pipe is disposed in the evaporator from the lower side to the upper side. As a result, the specification was such that the refrigerant and oil that flowed into the evaporator flowed from the bottom to the top, so that the oil was very difficult to flow. Thus, when oil accumulates in the refrigerant piping of the evaporator, the flow rate of the refrigerant flowing through the refrigerant passage in the refrigerant piping is lowered by the oil, and the heat transfer coefficient is also deteriorated.

  In particular, when carbon dioxide is used as a refrigerant, the carbon dioxide is a refrigerant with a large difference in high and low pressure, and the pressure on the high pressure side is significantly higher than other refrigerants, considering durability, Due to the fact that high viscosity oil is used and the density of carbon dioxide refrigerant is higher than that of other refrigerants, the flow rate is slower, so it is more dependent on the oil pool in the heat exchanger than the refrigerant cycle device using other refrigerants. The deterioration of heat exchange performance was more serious.

  On the other hand, in the present invention, the refrigerant inlet 157A of the evaporator 157 is formed at one upper end of the evaporator 157, and the refrigerant outlet 157B is formed at the lower end of the other end so that the refrigerant flows from the upper part of the evaporator 157, Since the refrigerant flows out from the lower portion of the evaporator 157, the oil that has flowed into the evaporator 157 can flow from the top to the bottom. As a result, the oil in the refrigerant pipe 101 can be caused to flow down by gravity, and the oil that tends to accumulate in the evaporator 157 can be made to flow easily. Accordingly, the oil does not easily accumulate in the refrigerant pipe 101, and can be smoothly discharged from the evaporator 157.

  As described above, the refrigerant can be smoothly discharged from the evaporator 157 by flowing the refrigerant from the upper part of the evaporator 157 and flowing the refrigerant from the lower part of the evaporator 157. It is possible to avoid the inconvenience that the refrigerant flowing through hinders heat exchange by oil. Thereby, the heat exchange performance of the evaporator 157 is improved, and good heat exchange can be performed.

  Further, by discharging the oil from the evaporator 157, the discharged oil comes out from the refrigerant outlet 157B together with the refrigerant and smoothly returns to the compressor 10 from the refrigerant introduction pipe 94. The inconvenience of falling into can also be eliminated.

  As described in detail above, according to the present invention, the oil accumulated in the evaporator 157 can be smoothly discharged to improve the heat exchanging capacity, and the shortage of oil in the compressor 10 can be solved. become. Therefore, the performance and reliability of the refrigerant cycle device 1 can be improved by the present invention.

  In the present embodiment, the fin-and-tube heat exchanger is used as the evaporator 157, but the present invention may be applied to other heat exchangers, for example, a microtube heat exchanger. .

  Further, in this embodiment, carbon dioxide is used as the refrigerant of the refrigerant cycle device 1, but the invention of claim 1 is not limited to this, and the refrigerant cycle device using other refrigerants is also used. It is valid.

It is a refrigerant circuit figure of the refrigerant cycle device of the example to which the present invention is applied. It is a front view of the evaporator of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerant cycle apparatus 10 Compressor 12 Airtight container 14 Electric element 32 1st rotation compression element 34 2nd rotation compression element 92, 94 Refrigerant introduction pipe 96 Refrigerant discharge pipe 101 Refrigerant piping 121 Tube plate 122 Fin 154 Radiator 156 Expansion valve 157 evaporator

Claims (2)

In the refrigerant cycle device in which the refrigerant cycle is configured from a compressor, a radiator, a decompressor, an evaporator, etc.
A refrigerant cycle apparatus, wherein a refrigerant is introduced from an upper part of the evaporator and a refrigerant is caused to flow out from a lower part of the evaporator.   The refrigerant cycle apparatus according to claim 1, wherein a predetermined amount of carbon dioxide is sealed as a refrigerant.

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