JP4048853B2 - Ejector cycle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ejector cycle.
[0002]
[Prior art and problems to be solved by the invention]
As is well known, the ejector cycle is a vapor that decompresses and expands the refrigerant in the ejector and sucks the gas-phase refrigerant evaporated in the evaporator, and converts the expansion energy into pressure energy to increase the suction pressure of the compressor. This is a compression refrigerator.
[0003]
Specifically, in the ejector cycle, a refrigerant flow (hereinafter referred to as a driving flow) that circulates in the order of a compressor, a radiator, an ejector, a gas-liquid separator, and a compressor, and a gas-liquid separator, an evaporator, and an ejector. → There is a refrigerant flow (hereinafter referred to as suction flow) that circulates in the order of the gas-liquid separator, and the suction flow uses the energy of the high-pressure refrigerant compressed by the compressor (JIS Z). 8126 number 2.1.2.3 etc.).
[0004]
By the way, in a vapor compression type refrigerator (hereinafter referred to as an expansion valve cycle) in which the refrigerant is decompressed in an enthalpy manner by decompression means such as an expansion valve, the compressor removes the refrigerant flowing out of the expansion valve and flowing into the evaporator. In contrast to the direct suction, in the ejector cycle, the compressor does not suck the refrigerant in the evaporator but sucks the refrigerant in the gas-liquid separator.
[0005]
In the ejector cycle, not only the liquid-phase refrigerant supplied to the evaporator but also the refrigeration oil circulating with the refrigerant is returned to the compressor, so that a relatively large amount of liquid-phase component is stored in the gas-liquid separator. In the separator, the refrigeration oil and the liquid refrigerant are separated, and the refrigeration oil is returned to the compressor.
[0006]
For this reason, the gas-liquid separator for the ejector cycle has a problem that it is difficult to reduce the size of the gas-liquid separator because it is necessary to store a large amount of liquid phase components in the gas-liquid separator. .
[0007]
Incidentally, the refrigeration oil is a lubricating oil that lubricates the sliding portion of the compressor. In a general vapor compression refrigerator, the sliding portion in the compressor is lubricated by mixing the refrigeration oil with a refrigerant.
[0008]
In view of the above points, the present invention firstly provides a new ejector cycle different from the conventional one, and secondly, it aims to reduce the size of the gas-liquid separator for the ejector cycle.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a vapor compression type ejector cycle in which the heat on the low temperature side is moved to the high temperature side, and the high pressure discharged from the compressor (10). A high-pressure side heat exchanger (20) that dissipates the heat of the refrigerant, a low-pressure side heat exchanger (30) that evaporates the low-pressure refrigerant, and a nozzle (41) that decompresses and expands the high-pressure refrigerant isentropically. (41) sucks the vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) by the high-speed refrigerant flow injected from the refrigerant, and converts the expansion energy into pressure energy to reduce the suction pressure of the compressor (10). The ejector (40) to be raised, the refrigerant flowing out from the ejector (40) is separated into a gas phase refrigerant and a liquid phase refrigerant, and the gas phase refrigerant outlet is connected to the suction side of the compressor (10). Outlet for low pressure side heat exchanger 30), a refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10), and a refrigerant passage ( 80) and a valve (71) that allows the refrigerant to flow only from the refrigerant outlet side of the low-pressure side heat exchanger (30) to the refrigerant suction side of the compressor (10) , and the refrigerant passage (80) The piping member, the valve (71), and the gas-liquid separator (50) that constitute the above are integrated .
[0010]
Thereby, since the refrigerating machine oil which retains in an evaporator (30) can be returned to a compressor (10), it is not necessary to store a lot of liquid phase components in a gas-liquid separator (50), and a gas-liquid separator (50) can be reduced in size, and a new ejector cycle different from the conventional one can be obtained.
[0011]
The invention according to claim 2 is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side, and radiates the heat of the high-pressure refrigerant discharged from the compressor (10) ( 20), a low-pressure side heat exchanger (30) for evaporating the low-pressure refrigerant, and a nozzle (41) for decompressing and expanding the high-pressure refrigerant in an isentropic manner, and a high-speed refrigerant flow injected from the nozzle (41) An ejector (40) that sucks the vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) and converts the expansion energy into pressure energy to increase the suction pressure of the compressor (10), and the ejector (40) The refrigerant flowing out of the refrigerant is separated into a gas phase refrigerant and a liquid phase refrigerant, the gas phase refrigerant outlet is connected to the suction side of the compressor (10), and the liquid phase refrigerant outlet is connected to the low pressure side heat exchanger (30). Connected gas-liquid separation means (5 ), The refrigerant passage (80) connecting the refrigerant outlet side of the low-pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10), and the refrigerant passage (80), and the low-pressure side heat exchanger ( 30) A valve (71) that opens the refrigerant passage (80) when the pressure on the refrigerant outlet side of 30) becomes larger than the pressure on the refrigerant suction side of the compressor (10) and the pressure difference becomes a predetermined pressure difference or more. ), And a piping member, a valve (71), and a gas-liquid separator (50) constituting the refrigerant passage (80) are integrated .
[0012]
Thereby, since the refrigerating machine oil which retains in an evaporator (30) can be returned to a compressor (10), it is not necessary to store a lot of liquid phase components in a gas-liquid separator (50), and a gas-liquid separator (50) can be reduced in size, and a new ejector cycle different from the conventional one can be obtained.
[0013]
The invention according to claim 3 is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side, and radiates the heat of the high-pressure refrigerant discharged from the compressor (10) ( 20), a low-pressure side heat exchanger (30) for evaporating the low-pressure refrigerant, and a nozzle (41) for decompressing and expanding the high-pressure refrigerant in an isentropic manner, and a high-speed refrigerant flow injected from the nozzle (41) An ejector (40) that sucks the vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) and converts the expansion energy into pressure energy to increase the suction pressure of the compressor (10), and the ejector (40) The refrigerant flowing out of the refrigerant is separated into a gas phase refrigerant and a liquid phase refrigerant, the gas phase refrigerant outlet is connected to the suction side of the compressor (10), and the liquid phase refrigerant outlet is connected to the low pressure side heat exchanger (30). Connected gas-liquid separation means (5 ), The refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10), and the pressure on the refrigerant outlet side of the low pressure side heat exchanger (30) An electric valve (73, 74) that causes the refrigerant to flow into the refrigerant passage (80) when the pressure on the refrigerant suction side of the compressor (10) becomes larger than the pressure difference and becomes equal to or larger than a predetermined pressure difference; And a piping member, a valve (73, 74), and a gas-liquid separator (50) constituting the refrigerant passage (80) are integrated .
[0014]
Thereby, since the refrigerating machine oil which retains in an evaporator (30) can be returned to a compressor (10), it is not necessary to store a lot of liquid phase components in a gas-liquid separator (50), and a gas-liquid separator (50) can be reduced in size, and a new ejector cycle different from the conventional one can be obtained.
[0016]
Incidentally, the reference numerals in parentheses of each means described above are an example showing the correspondence with the specific means described in the embodiments described later.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
In the present embodiment, the ejector cycle according to the present invention is applied to a vapor compression refrigerator for a showcase that refrigerates and stores food, and FIG. 1 is a schematic diagram of the ejector cycle.
[0018]
The compressor 10 is an electric compressor that sucks and compresses refrigerant, and the radiator 20 exchanges heat between the high-temperature and high-pressure refrigerant discharged from the compressor 10 and the outdoor air to cool the refrigerant. It is.
[0019]
The evaporator 30 is a low-pressure side heat exchanger that exhibits a refrigerating capacity by heat-exchanging the air blown into the showcase and the low-pressure refrigerant to evaporate the liquid-phase refrigerant. The ejector expands the refrigerant flowing out under reduced pressure and sucks the gas-phase refrigerant evaporated in the evaporator 30 and converts the expansion energy into pressure energy to increase the suction pressure of the compressor 10.
[0020]
As shown in FIG. 2, the ejector 40 converts the pressure energy of the inflowing high-pressure refrigerant into velocity energy and isentropically decompressed and expanded, and the high-speed refrigerant flow injected from the nozzle 41. While sucking the gas-phase refrigerant evaporated in the evaporator 30 by the entrainment action, the mixing unit 42 that mixes the refrigerant flow ejected from the nozzle 41 and the refrigerant ejected from the nozzle 41 and the refrigerant sucked from the evaporator 30 It is composed of a diffuser 43 or the like for increasing the pressure of the refrigerant by converting velocity energy into pressure energy while mixing.
[0021]
At this time, in the mixing unit 42, the driving flow and the suction flow are mixed so that the sum of the momentum of the driving flow and the momentum of the suction flow is preserved. ) Will rise.
[0022]
On the other hand, in the diffuser 43, the velocity energy (dynamic pressure) of the refrigerant is converted into pressure energy (static pressure) by gradually increasing the cross-sectional area of the passage, so that in the ejector 40, the mixing section 42 and the diffuser 43 Both increase the refrigerant pressure. Therefore, hereinafter, the mixing unit 42 and the diffuser 43 are collectively referred to as a boosting unit.
[0023]
Incidentally, in the present embodiment, in order to accelerate the speed of the refrigerant ejected from the nozzle 41 to the sound speed or higher, a Laval nozzle having a throat portion 41a whose passage area is most reduced in the middle of the passage (see Fluid Engineering (Tokyo University Press)) Of course, it goes without saying that a tapered nozzle may be adopted.
[0024]
In FIG. 1, the gas-liquid separator 50 is gas-liquid separation means for storing the refrigerant by flowing the refrigerant flowing out from the ejector 40 and separating the flowing refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant, The gas-phase refrigerant outlet of the gas-liquid separator 50 is connected to the suction side of the compressor 10, and the liquid-phase refrigerant outlet is connected to the evaporator 30 side.
[0025]
The restrictor 60 is a decompression unit that decompresses the liquid-phase refrigerant flowing out from the gas-liquid separator 50, and the oil return passage 70 is a refrigerant passage that connects the refrigerant outlet side of the evaporator 30 and the refrigerant suction side of the compressor 10. The oil return passage 70 is provided with a check valve 71 that only allows the refrigerant to flow from the refrigerant outlet side of the evaporator 30 toward the refrigerant suction side of the compressor 10. By opening and closing, the case where the refrigerant flows through the oil return passage 70 and the case where the refrigerant does not flow are controlled.
[0026]
Here, the check valve 71 includes a valve body 71a that opens and closes the valve opening, and a spring 71b that applies an elastic force to the valve body 71a to close the valve opening. The spring 71b opens the oil return passage 70 when the pressure on the refrigerant outlet side of the evaporator 30 becomes larger than the pressure on the refrigerant suction side of the compressor 10 and the pressure difference becomes a predetermined pressure difference or more. Is set.
[0027]
The check valve 71 in FIG. 1 is a check valve symbol according to JIS B 0125, and the shapes of the valve body 71a and the spring 71b shown in FIG. 1 do not necessarily indicate actual shapes. .
[0028]
The internal heat exchanger 80 is a heat exchanger that exchanges heat between the high-pressure refrigerant flowing out of the radiator 20 and the low-pressure refrigerant sucked into the compressor 10, and the flow control valve 90 is disposed on the inlet side of the nozzle 41. This is a valve that controls the throttle opening so that the degree of refrigerant superheating on the refrigerant outlet side of the evaporator 30 becomes a predetermined value.
[0029]
Incidentally, in this embodiment, while making a refrigerant into a carbon dioxide, as shown in FIG. 3, the high pressure refrigerant | coolant which flows in into the nozzle 41 with the compressor 10 is pressure | voltage-risen more than the critical pressure of a refrigerant | coolant. Incidentally, the symbol indicated by ● in FIG. 3 indicates the state of the refrigerant at the symbol position indicated by ● in FIG.
[0030]
Next, the operation and characteristic points of the cycle according to this embodiment will be described.
[0031]
1. Normal operation mode (see Fig. 3)
The refrigerant discharged from the compressor 10 is circulated to the radiator 20 side. As a result, the refrigerant cooled by the radiator 20 is isentropically decompressed and expanded at the nozzle 41 of the ejector 40 and flows into the mixing unit 42 at a speed equal to or higher than the speed of sound.
[0032]
Then, since the refrigerant evaporated in the evaporator 30 is sucked into the mixing unit 42 by the pumping action accompanying the entrainment action of the high-speed refrigerant flowing into the mixing unit 42, the low-pressure side refrigerant is reduced to the gas-liquid separator 50 → throttle. It circulates in order of 60-> evaporator 30-> ejector 40 (pressure | voltage riser)-> gas-liquid separator 50.
[0033]
On the other hand, the refrigerant sucked from the evaporator 30 (suction flow) and the refrigerant blown out from the nozzle 41 (driving flow) are mixed by the mixing unit 42 and the dynamic pressure thereof is converted into static pressure by the diffuser 43. Return to the liquid separator 50.
[0034]
2. Oil return mode This mode is used when the refrigerating machine oil circulating in the ejector cycle while mixed with the refrigerant stays in the evaporator 30 for a predetermined amount or when the ejector efficiency ηe decreases such as when the outside air temperature decreases. Alternatively, this mode is automatically executed when the pumping action of the ejector 40 is lowered.
[0035]
Incidentally, the ejector efficiency ηe is the product of the mass flow rate Gn of the refrigerant flowing through the radiator 20 and the enthalpy difference Δie at the inlet / outlet of the nozzle 41, and how much energy is recovered as work of the compressor 10 in the numerator. This is defined by adding the sum of the refrigerant flow rate Gn indicating whether or not the refrigerant has flown and the mass flow rate Ge of the refrigerant flowing through the evaporator 30 and the pressure recovery ΔP in the ejector 40.
[0036]
That is, when the pumping action of the ejector 40 is sufficiently large, the pressure recovery ΔP at the ejector 40, that is, the pressure increase ΔP at the ejector 40 is large, so that the compressor 10 is sandwiched by the check valve 71 as shown in FIG. The pressure P3 on the refrigerant suction side becomes relatively larger than the pressure P1 on the refrigerant outlet side of the evaporator 30, the oil return passage 70 is closed by the check valve 71, and the refrigerant does not flow into the oil return passage 70.
[0037]
However, when the pumping action of the ejector 40 is reduced, the pressure P1 on the refrigerant outlet side of the evaporator 30 is relatively larger than the pressure P3 on the refrigerant suction side of the compressor 10 with the check valve 71 interposed therebetween. As shown, the check valve 71 opens and the refrigerant flows through the oil return passage 70.
[0038]
Therefore, since the refrigerant outlet side of the evaporator 30 directly communicates with the suction side of the compressor 10, the refrigerating machine oil staying in the evaporator 30 is directed toward the compressor 10 even if the pumping action of the ejector 40 is small. The refrigeration oil stays away.
[0039]
And if the refrigerating machine oil in the evaporator 30 decreases, the refrigerating capacity in the evaporator 30 increases and the flow rate of the suction flow and the drive flow increases, so the pump action of the ejector 40 increases, and the check valve 71 is turned on. The pressure P3 on the refrigerant suction side of the compressor 10 is relatively larger than the pressure P1 on the refrigerant outlet side of the evaporator 30.
[0040]
That is, when the refrigerating machine oil in the evaporator 30 decreases, the check valve 71 closes and automatically shifts from the oil return mode to the normal operation mode, and conversely, when a large amount of refrigerating machine oil in the evaporator 30 accumulates, The check valve 71 is opened and automatically shifts from the normal operation mode to the oil return mode.
[0041]
As described above, in this embodiment, since the refrigerating machine oil staying in the evaporator 30 can be controlled to a predetermined amount or less and a sufficient amount of refrigerating machine oil can be returned to the compressor 10, the gas-liquid separator It is not necessary to store a large amount of liquid phase component in 50, and the gas-liquid separator 50 can be downsized.
[0042]
(Second Embodiment)
In the present embodiment, as shown in FIG. 6, the pressure on the refrigerant outlet side of the evaporator 30 is reduced by eliminating the spring 71 b of the check valve 71 or making the elastic force of the spring 71 b extremely small. The oil return passage 70 is configured to open when the pressure becomes higher than the refrigerant suction side pressure.
[0043]
(Third embodiment)
In the first embodiment, the oil return passage 70 is opened and closed by a check valve 71 that is a mechanical valve. However, in the present embodiment, an electromagnetic valve 73 is used instead of the check valve 71 as shown in FIG. The pressure sensor 72a, 72b detects the pressure increase amount ΔP at the ejector 40, and when the pressure increase amount ΔP at the ejector 40 falls below a predetermined value, the electromagnetic valve 73 is opened, and the pressure increase amount ΔP at the ejector 40 becomes a predetermined value. The electromagnetic valve 73 is closed when the value exceeds.
[0044]
In addition, this embodiment can be implemented even if the predetermined value when closing the electromagnetic valve 73 and the predetermined value when closing the electromagnetic valve 73 are different.
[0045]
Further, in the present embodiment, the opening / closing control of the electromagnetic valve 73 is performed using the pressure increase ΔP in the ejector 40 as a parameter. However, the present embodiment is not limited to this, and for example, the rotational speed of the compressor 10, the refrigerant The ejector efficiency ηe is calculated from the temperature, the refrigerant pressure, etc., and the electromagnetic valve 73 is opened when the ejector efficiency ηe becomes a predetermined value or less, and the electromagnetic valve 73 is closed when the ejector efficiency ηe exceeds the predetermined value. Also good. At this time, it goes without saying that the predetermined value of the ejector efficiency ηe when the electromagnetic valve 73 is closed may be different from the predetermined value of the ejector efficiency ηe when the electromagnetic valve 73 is closed.
[0046]
(Fourth embodiment)
This embodiment is a modification of the third embodiment. Specifically, as shown in FIGS. 8 and 9, three types of solenoid valves are provided at the branching or joining portion between the low-pressure side refrigerant passage and the oil return passage 70. 74 is provided so that the electromagnetic valve 82 is opened when the pressure increase amount ΔP at the ejector 40 is less than a predetermined value, and the electromagnetic valve 74 is closed when the pressure increase amount ΔP at the ejector 40 exceeds a predetermined value. Is.
[0047]
8 shows an example in which the electromagnetic valve 74 is arranged at the refrigerant branching portion on the outlet side of the evaporator 30, and FIG. 9 is an example in which the electromagnetic valve 74 is arranged in the refrigerant confluence portion on the outlet side of the ejector 40.
[0048]
(Fifth embodiment)
In the present embodiment, as shown in FIG. 10, piping constituting the oil return passage 70, the ejector 40, the gas-liquid separator 50, the check valve 71, the flow rate control valve 90, and the like (location surrounded by broken lines in FIG. 1). ).
[0049]
In addition, although FIG. 10 applied this embodiment with respect to 1st Embodiment, this embodiment is not limited to this, It applies also to 2nd-4th Embodiment. Needless to say, you can.
[0050]
(Other embodiments)
In the above-described embodiment, carbon dioxide is used as the refrigerant. However, the present invention is not limited to this, and for example, hydrocarbon, chlorofluorocarbon, or the like may be used as the refrigerant.
[0051]
In the above-described embodiment, the high-pressure side refrigerant pressure is set to be equal to or higher than the critical pressure, but the present invention is not limited to this.
[0052]
In the above-described embodiment, the ejector cycle according to the present invention is applied to a vapor compression refrigerator for a showcase that refrigerates and stores food, but the application of the present invention is not limited to this. For example, it can be applied to an air conditioner.
[0053]
The present invention is not limited to the above-described embodiment because the compressor 10 directly sucks the refrigerating machine oil in the evaporator 30 during the oil return mode.
[0054]
Further, at least one of the flow control valve 90 and the internal heat exchanger 80 may be eliminated.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an ejector cycle according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram of an ejector according to an embodiment of the present invention.
FIG. 3 is a ph diagram.
FIG. 4 is an operation explanatory diagram of an ejector cycle according to the first embodiment of the present invention.
FIG. 5 is an operation explanatory diagram of an ejector cycle according to the first embodiment of the present invention.
FIG. 6 is a schematic diagram of an ejector cycle according to a second embodiment of the present invention.
FIG. 7 is a schematic diagram of an ejector cycle according to a third embodiment of the present invention.
FIG. 8 is a schematic diagram of an ejector cycle according to a fourth embodiment of the present invention.
FIG. 9 is a schematic diagram of an ejector cycle according to a fourth embodiment of the present invention.
FIG. 10 is an explanatory diagram showing features of an ejector cycle according to a fifth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Compressor, 20 ... Radiator, 30 ... Evaporator, 40 ... Ejector,
50 ... Gas-liquid separator, 60 ... Restriction, 70 ... Oil return passage, 71 ... Check valve.

Claims (3)

It is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side,
A high-pressure side heat exchanger (20) that dissipates heat of the high-pressure refrigerant discharged from the compressor (10);
A low pressure side heat exchanger (30) for evaporating the low pressure refrigerant;
It has a nozzle (41) that decompresses and expands high-pressure refrigerant in an isentropic manner, and sucks vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) by a high-speed refrigerant flow injected from the nozzle (41). And an ejector (40) for converting the expansion energy into pressure energy to increase the suction pressure of the compressor (10),
The refrigerant flowing out from the ejector (40) is separated into a gas phase refrigerant and a liquid phase refrigerant, a gas phase refrigerant outlet is connected to the suction side of the compressor (10), and a liquid phase refrigerant outlet is the low pressure side. A gas-liquid separation means (50) connected to the heat exchanger (30);
A refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10);
A valve (71) provided in the refrigerant passage (80) and allowing the refrigerant to flow only to the refrigerant suction side of the compressor (10) from the refrigerant outlet side of the low-pressure side heat exchanger (30). e,
An ejector cycle , wherein a piping member constituting the refrigerant passage (80), the valve (71), and the gas-liquid separator (50) are integrated . It is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side,
A high-pressure side heat exchanger (20) that dissipates heat of the high-pressure refrigerant discharged from the compressor (10);
A low pressure side heat exchanger (30) for evaporating the low pressure refrigerant;
It has a nozzle (41) that decompresses and expands high-pressure refrigerant in an isentropic manner, and sucks vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) by a high-speed refrigerant flow injected from the nozzle (41). And an ejector (40) for converting the expansion energy into pressure energy to increase the suction pressure of the compressor (10),
The refrigerant flowing out from the ejector (40) is separated into a gas phase refrigerant and a liquid phase refrigerant, a gas phase refrigerant outlet is connected to the suction side of the compressor (10), and a liquid phase refrigerant outlet is the low pressure side. A gas-liquid separation means (50) connected to the heat exchanger (30);
A refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10);
The pressure on the refrigerant outlet side of the low pressure side heat exchanger (30) provided in the refrigerant passage (80) is larger than the pressure on the refrigerant suction side of the compressor (10), and the pressure difference is a predetermined pressure. when a difference above example Bei a valve (71) opening said refrigerant passage (80),
An ejector cycle , wherein a piping member constituting the refrigerant passage (80), the valve (71), and the gas-liquid separator (50) are integrated . It is a vapor compression type ejector cycle that moves the heat on the low temperature side to the high temperature side,
A high-pressure side heat exchanger (20) that dissipates heat of the high-pressure refrigerant discharged from the compressor (10);
A low pressure side heat exchanger (30) for evaporating the low pressure refrigerant;
It has a nozzle (41) that decompresses and expands high-pressure refrigerant in an isentropic manner, and sucks vapor-phase refrigerant evaporated in the low-pressure side heat exchanger (30) by a high-speed refrigerant flow injected from the nozzle (41). And an ejector (40) for converting the expansion energy into pressure energy to increase the suction pressure of the compressor (10),
The refrigerant flowing out from the ejector (40) is separated into a gas phase refrigerant and a liquid phase refrigerant, a gas phase refrigerant outlet is connected to the suction side of the compressor (10), and a liquid phase refrigerant outlet is the low pressure side. A gas-liquid separation means (50) connected to the heat exchanger (30);
A refrigerant passage (80) connecting the refrigerant outlet side of the low pressure side heat exchanger (30) and the refrigerant suction side of the compressor (10);
When the pressure on the refrigerant outlet side of the low-pressure side heat exchanger (30) is larger than the pressure on the refrigerant suction side of the compressor (10) and the pressure difference becomes a predetermined pressure difference or more, the refrigerant e Bei the electric valve (73, 74) for allowing the refrigerant to flow through the passage (80),
An ejector cycle , wherein a piping member constituting the refrigerant passage (80), the valves (73, 74), and the gas-liquid separator (50) are integrated .

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