JP4182148B2 - accumulator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an accumulator used in a refrigeration cycle in which, for example, carbon dioxide is used as a refrigerant, and the refrigerant is compressed to a region below a critical point at a low load.
[0002]
[Prior art]
Japanese Patent Publication No. 7-18602 discloses a refrigeration cycle in which a compressor, a cooling device, and a throttle connected in series so as to form an integrated closed circuit that operates at a supercritical pressure on the high-pressure side of a vapor compression cycle. A supercritical vapor compression cycle comprising an apparatus, an evaporator and an accumulator is disclosed.
[0003]
In this refrigeration cycle, the gas-phase refrigerant sucked into the compressor is compressed to the supercritical region and discharged and cooled by the cooling device. Normally, the refrigerant is not condensed unlike the conventional Freon refrigeration cycle. It is sent to the diaphragm means in the phase state. Then, the pressure is reduced to the gas-liquid mixing region by this throttling means to generate a liquid phase component, and the refrigerant in a gas-liquid two-phase state absorbs the heat of the air passing through the evaporator and evaporates. Further, the accumulator Thus, the liquid phase component is completely removed and sucked into the compressor.
[0004]
In the refrigeration cycle described above, as a method for adjusting the opening degree of the throttle means, there is a method that depends on the high pressure and temperature of the refrigeration cycle. It is known from Japanese Patent Application Laid-Open No. 9-264622 that a high pressure pressure that can be obtained is used as a reference and the throttling means is controlled so as to match the high pressure with this pressure.
[0005]
As compressors, compressors that can change the compression and discharge capacity of the refrigerant are widely used, for example, those disclosed in Japanese Patent Application Laid-Open No. 05-202849. Such a change in the capacity of the compressor is often performed depending on the suction pressure of the compressor, that is, the low pressure of the refrigeration cycle. When the refrigerant pressure decreases at low load, the capacity of the compressor decreases, and the refrigerant It operates so that the discharge amount is reduced.
[0006]
[Problems to be solved by the invention]
However, in the conventional refrigeration cycle using carbon dioxide as described above, when the outside air temperature is low and the load is reduced, the high pressure of the refrigeration cycle becomes lower than the critical pressure, so the refrigerant is condensed in the radiator (gas cooler). Occurs. For this reason, the high pressure is decreased, the expansion device (throttle means) that senses this is closed to stop the flow of the refrigerant, and the compressor senses a decrease in the low pressure and reduces the refrigerant discharge amount. At this time, since the low-pressure pressure remains low, the capacity of the compressor does not increase and the high-pressure pressure does not rise easily, so the expansion device does not open easily, and even if it finally opens, the refrigerant suddenly flows from the high-pressure line to the low-pressure line. Therefore, a state like hunting that closes immediately occurs again. For this reason, the temperature of an evaporator rises abnormally and may cause the malfunction that an unpleasant feeling is given to a user.
[0007]
Therefore, an object of the present invention is to provide an accumulator that can prevent an abnormal temperature rise of an evaporator at a low load by promoting an increase in high pressure.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a hollow casing that contains a liquid-phase refrigerant, an inflow pipe that supplies the refrigerant flowing out of the evaporator to the inside of the casing, and a gas-phase refrigerant in the casing. In the accumulator having an outflow pipe that flows out in a certain stroke, heat exchange promoting means for promoting heat exchange between the refrigerant flowing into the casing via the inflow pipe and the liquid phase refrigerant accommodated in the casing (Claim 1).
[0009]
According to this, since the gas phase (gas-liquid mixture) refrigerant flowing into the accumulator and the liquid phase refrigerant in the accumulator are actively exchanged with heat, if the degree of superheat of the evaporator occurs, the accumulator The vaporization of the liquid phase refrigerant is promoted in the interior. As a result, the amount of refrigerant circulating in the refrigeration cycle increases, so the pressure in the high-pressure line from the compressor to the expansion device rises quickly, and the expansion valve closes at low load and refrigerant does not flow to the evaporator. The problem that the temperature of the evaporator rises abnormally can be prevented. In addition, as the temperature of the evaporator rises, the temperature of the refrigerant flowing into the accumulator also rises. Therefore, the more abnormal the temperature of the evaporator, the more the vaporization of the liquid phase refrigerant in the accumulator is promoted. , Acting in the direction of opening the expansion device.
[0010]
Further, the heat exchange promoting means may be a part of the inflow pipe formed so as to be positioned below the liquid level of the liquid phase refrigerant accommodated in the casing.
[0011]
According to this, since the inflow pipe is in contact with the liquid phase refrigerant in the casing, the refrigerant flowing into the accumulator and the liquid phase refrigerant accumulated in the accumulator are actively heated through the wall surface of the inflow pipe. Will be exchanged.
[0012]
Further, the inflow pipe is formed by being folded several times under the liquid level of the liquid phase refrigerant (Claim 3), or formed in the spiral shape (Claim 4), or when the fin is provided in the inflow pipe. Good (Claim 5).
[0013]
According to these, since the contact area between the inflow pipe and the liquid refrigerant in the accumulator increases, the heat exchange efficiency can be improved, and the increase in the high pressure can be further accelerated. For example, as a configuration in which the inflow pipe is folded back several times, the inflow pipe is extended from the upper part of the casing to the vicinity of the bottom where the liquid-phase refrigerant is accumulated, and is bent back and forth several times in the vicinity of the bottom, so And the like that are positioned upward. In addition, as the structure formed in a spiral shape, an inflow pipe is formed in a spiral shape from the top to the bottom, folded back at the bottom and opened above the liquid level, etc., and from the bottom to the top It may be a spiral to go.
[0014]
Further, the heat exchange promoting means may be a part of an outflow pipe formed so as to be positioned below the liquid level of the liquid phase refrigerant (Claim 6).
[0015]
This also facilitates heat exchange between the discharged gas-phase refrigerant and the liquid-phase refrigerant.
[0016]
The refrigerant is carbon dioxide (Claim 7).
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
The refrigeration cycle 1 shown in FIG. 1 uses carbon dioxide as a refrigerant. A compressor 2, a radiator (gas cooler) 3, an expansion device 4, an evaporator 5, an accumulator 6, and an internal heat exchanger 7 are connected by piping. And a high pressure line 10 from the discharge port 2a of the compressor 2 to the inlet 4a of the expansion device 4, and a low pressure line 11 from the outlet 4b of the expansion device 4 to the suction port 2b of the compressor 2. Have.
[0019]
With the above configuration, the gas-phase refrigerant sucked by the compressor 2 is compressed in the supercritical region during normal operation, and the compressed gas-phase refrigerant is cooled by heat exchange with air passing through the radiator 3. Is done. The gas-phase refrigerant cooled by the radiator 3 flows into the high-pressure channel 7a of the internal heat exchanger 7 and is further cooled by exchanging heat with the low-temperature and low-pressure refrigerant flowing through the low-pressure channel 7b. Then, the pressure is lowered to the gas-liquid mixing region through the expansion device 4. The gas-liquid mixed refrigerant depressurized by the expansion means 4 evaporates by taking the heat of the air passing through the evaporator 5, is vapor-liquid separated in the accumulator 6, and only the gas-phase refrigerant is the low pressure of the internal heat exchanger 7. The refrigerant flows into the side channel 7b, exchanges heat with the high-temperature and high-pressure refrigerant flowing through the high-pressure side channel 7a, and is sucked into the compressor 2.
[0020]
In the configuration of the present invention, the compressor 2 is such that the refrigerant compression and discharge capacity is changed according to the pressure of the low-pressure line 11, and the low-pressure pressure becomes low when the load is low. When this is sensed, the amount of compression and discharge is reduced. The expansion device 4 adjusts the opening degree of the valve in accordance with the pressure in the high pressure line 10 and closes the valve when it is detected that the high pressure is low at a low load or the like. The internal heat exchanger 7 is effective for improving the efficiency of the refrigeration cycle 1, but is not an essential component in the present invention.
[0021]
The accumulator 6 according to the first embodiment shown in FIG. 2 has a casing 15 that is hollow inside and has an opening at the top, a lid 16 that closes the opening at the top of the casing 15, and guides refrigerant from the outside to the inside of the casing 15. The inflow pipe 17 and the outflow pipe 18 that guides the gas-phase refrigerant in the casing 15 to the outside are configured. Liquid phase refrigerant accumulates in the vertical lower part (bottom part) B of the casing 15, and gas phase refrigerant accumulates in the vertical upper part T. The inflow pipe 17 and the outflow pipe 18 are formed of a material having high thermal conductivity such as aluminum.
[0022]
One end 17a of the inflow pipe 17 is connected to the pipe 12 through which the refrigerant flowing out of the evaporator 5 flows through the inflow passage hole 16a formed in the lid body 16, and the other end 17b is connected to the casing. 15, the tube portion 17 c between the one end portion 17 a and the other end portion 17 b is positioned below the liquid level near the bottom B of the casing 15 so as to come into contact with the liquid phase refrigerant L. In this embodiment, it is formed by turning up, down and up three times.
[0023]
Further, the outflow pipe 18 has one end 18 a located at the upper portion T of the casing 15, and the other end 18 b to the internal heat exchanger 7 through an outflow passage 16 b formed in the lid body 16. The pipe portion 18c between the one end portion 18a and the other end portion 18b is folded back in the vicinity of the bottom B of the casing 15 so as to come into contact with the liquid phase refrigerant L. ing.
[0024]
According to the above configuration, when the vapor phase or gas-liquid mixed refrigerant that has taken heat from the surrounding air in the evaporator 5 flows into the accumulator 6, the contact area with the liquid phase refrigerant L is folded back. Therefore, the heat exchange with the liquid refrigerant L is performed via the wall surface of the pipe portion 17 c, and then discharged to the upper portion T in the casing 15. Further, when the gas-phase refrigerant G accumulated in the upper portion T in the casing 15 flows out through the outflow pipe 18, heat exchange with the liquid-phase refrigerant L is also performed.
[0025]
As a result, the refrigerant discharge amount of the compressor 2 is reduced at a low load, and the refrigerant is condensed in the high-pressure line 10, so that even if the high-pressure pressure is reduced, the refrigeration cycle is actively performed in the accumulator 6. Since the release of the liquid-phase refrigerant L into the interior 1 is promoted, the amount of refrigerant discharged from the compressor 2 is increased, and the pressure of the high-pressure line 10 is increased. As a result, the expansion device 4 can be prevented from being closed and the temperature of the evaporator 5 can be prevented from rising abnormally.
[0026]
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. The same reference numerals are given to the same portions as those of the first embodiment and the portions having the same functions as those of the first embodiment. Is omitted.
[0027]
As shown in FIG. 3, the accumulator 6 according to the second embodiment of the present invention is formed in a spiral shape so that the pipe portion 17c of the inflow pipe 17 is in contact with the liquid refrigerant L downward. Is. This also increases the contact area between the inflow pipe 17 and the liquid phase refrigerant L, so that heat exchange between the refrigerant in the inflow pipe 17 and the liquid phase refrigerant L can be performed positively.
[0028]
Further, as shown in FIG. 4, the accumulator 6 in the third embodiment is formed by folding the pipe portion 17c of the inflow pipe 17 in the vicinity of the bottom portion B of the casing 15 so as to be in contact with the liquid-phase refrigerant L. In addition, a plurality of fins 20 are fixed to the outer wall surface of the pipe portion 17c integrally or by brazing. The fin 20 is made of a material having high thermal conductivity such as aluminum, and the contact area between the inflow pipe 17 and the liquid refrigerant L is increased by the fin 20, so that the heat exchange efficiency can be further improved.
[0029]
【The invention's effect】
As described above, according to the present invention, the heat exchange between the refrigerant flowing into the accumulator and the liquid-phase refrigerant accumulated in the accumulator is actively performed, so that the release of the refrigerant into the cycle is promoted. , Increase the high pressure can be accelerated. Thereby, the abnormal temperature rise of the evaporator at the time of low load can be prevented.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a refrigeration cycle in the present invention.
FIG. 2 is a cross-sectional view showing the internal structure of the accumulator according to the first embodiment of the invention.
FIG. 3 is a cross-sectional view showing an internal structure of an accumulator according to a second embodiment of the present invention.
FIG. 4 is a cross-sectional view showing the internal structure of an accumulator according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 2 Compressor 3 Radiator 4 Expansion apparatus 5 Evaporator 6 Accumulator 7 Internal heat exchanger 10 High pressure line 11 Low pressure line 15 Casing 16 Lid 17 Inflow pipe 18 Outflow pipe 20 Fin B Vertical lower part (bottom part)
G Gas phase refrigerant L Liquid phase refrigerant T Vertically upper part

Claims (7)

An accumulator comprising a hollow casing for accommodating a liquid-phase refrigerant, an inflow pipe for supplying the refrigerant flowing out of the evaporator to the inside of the casing, and an outflow pipe for flowing out the gas-phase refrigerant in the casing to the next stroke In
An accumulator comprising heat exchange promoting means for promoting heat exchange between the refrigerant flowing into the casing through the inflow pipe and the liquid phase refrigerant accommodated in the casing. The accumulator according to claim 1, wherein the heat exchange promoting means is a part of the inflow pipe formed so as to be positioned below a liquid surface of the liquid phase refrigerant accommodated in the casing. 3. The accumulator according to claim 2, wherein a part of the inflow pipe is formed by being folded back several times below the liquid level of the liquid phase refrigerant. 3. The accumulator according to claim 2, wherein a part of the inflow pipe is formed in a spiral shape below the liquid level of the liquid-phase refrigerant. The accumulator according to any one of claims 1 to 4, wherein the heat exchange promoting means further includes fins formed in a part of the inflow pipe. The accumulator according to any one of claims 1 to 5, wherein the heat exchange promoting means is a part of an outflow pipe formed so as to be positioned below the liquid level of the liquid refrigerant. The accumulator according to claim 1, wherein the refrigerant is carbon dioxide.

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