WO2020157806A1

WO2020157806A1 - Refrigerator

Info

Publication number: WO2020157806A1
Application number: PCT/JP2019/002791
Authority: WO
Inventors: 松田　弘文; 雄亮田代
Original assignee: 三菱電機株式会社
Priority date: 2019-01-28
Filing date: 2019-01-28
Publication date: 2020-08-06
Also published as: JPWO2020157806A1; JP6952916B2

Abstract

This refrigerator (100) comprises a refrigerant circuit in which a refrigerant is circulated through a compressor (1), an oil separator (5), a condenser (2), a first throttle device (3), and an evaporator (4) in the stated order. The compressor includes a suction opening, a discharge opening, and a compression part that is lubricated with oil. The oil separator is provided so as to separate oil and refrigerant that are discharged from the discharge opening. The refrigerator (100) furthermore comprises an oil return passage (17) provided so that the oil separated in the oil separator when driving of the compressor is stopped is returned to a fifth flow passage (15) connecting the evaporator and the suction opening. The fifth flow passage has a connection part (18) connected to the oil return passage, a first rising pipe part (31) that is disposed between the connection part and the evaporator and that extends along the vertical direction, and a third rising pipe part (33) that is disposed between the connection part and the suction opening. The inside diameter of the first rising pipe part is greater than the inside diameter of the third rising pipe part.

Description

refrigerator

The present invention relates to a refrigerator.

Japanese Patent No. 3485006 discloses a refrigerant circuit including a compressor, a condenser, a throttle device, an evaporator as a cooler, and an oil separator, and an oil return path connected to the refrigerant circuit and including a solenoid valve. A refrigerator comprising is disclosed.

In compressors used in refrigerators, the compression part for compressing the refrigerant is generally lubricated with lubricating oil. In such a compressor, a part of the lubricating oil is discharged into the refrigerant circuit together with the refrigerant compressed by the compression section. In such a case, compared with the case where only the refrigerant flows through the refrigerant circuit, the pressure loss of the fluid flowing through the refrigerant circuit becomes large, the heat transfer property of the fluid decreases, and the cooling capacity of the refrigerator decreases.

Therefore, in the above refrigerator, an oil separator is arranged between the compressor and the condenser to separate the lubricating oil from the refrigerant discharged from the compressor. The oil return passage is provided so as to return the lubricating oil separated in the oil separator to the suction port of the compressor, and one end thereof is connected to the oil separator in which the relatively high-pressure refrigerant flows in the refrigerant circuit, The other end is connected between the evaporator and the suction port of the compressor in which a relatively low-pressure refrigerant flows in the refrigerant circuit. The solenoid valve is provided so as to open or close the oil return passage.

As a result, the lubricating oil separated by the oil separator receives the pressure difference between the one end and the other end of the oil return passage when the oil return passage is opened by the solenoid valve, and receives the other end. Be carried to.

Furthermore, in the above refrigerator, in order to prevent the lubricating oil returned to the refrigerant circuit from the other end of the oil return passage from flowing into the evaporator, in the refrigerant circuit, the connection portion with the other end of the oil return passage and evaporation are evaporated. An on-off valve such as a check valve or a solenoid valve is arranged between the container and the container.

Patent No. 3485006

However, in the above refrigerator, chattering may occur at the open/close valve. When chattering occurs, there is a problem that chattering sound is generated.

The main object of the present invention is to provide a refrigerator in which the lubricating oil returned from the oil return passage to the refrigerant circuit can be suppressed from flowing into the evaporator and chattering is suppressed.

The refrigerator according to the present invention includes a compressor, an oil separator, a condenser, a throttle device, and an evaporator, and is provided with a refrigerant circuit in which a refrigerant circulates through the compressor, the condenser, the throttle device, and the evaporator in order. The compressor has a suction port that sucks the refrigerant evaporated in the evaporator, a compression unit that is lubricated by oil and that compresses the refrigerant that is sucked from the suction port, and a discharge port that discharges the refrigerant that is compressed by the compression unit. Including and The refrigerant circuit has a first refrigerant flow path connecting between the evaporator and the suction port. The oil separator is provided so as to separate the refrigerant and the oil discharged from the discharge port. The refrigerator has a first end connected to the oil separator and the other end connected to the first refrigerant flow path, and removes the oil separated in the oil separator when the compressor is stopped. An oil return passage provided so as to return to the first refrigerant passage is further provided. The first refrigerant flow passage is connected to a connection portion connected to the oil return passage, and at least one first pipe portion arranged between the connection portion and the evaporator and extending in the vertical direction. And a pipe portion arranged between the portion and the suction port. The inner diameter of at least one 1st pipe part is larger than the inner diameter of the piping which comprises an oil return channel.

According to the present invention, it is possible to provide a refrigerator in which the lubricating oil returned from the oil return path to the refrigerant circuit can be suppressed from flowing into the evaporator and chattering is suppressed.

It is a figure which shows the refrigerant circuit and oil return path of the refrigerator which concerns on Embodiment 1. It is a figure which shows the example of arrangement|positioning of the rising pipe part in the refrigerant circuit of the refrigerator shown in FIG. 3 is a graph showing the relationship between the zero penetration speed in the rising tube section shown in FIG. 2 and the inner diameter of the rising tube section. It is a graph which shows the relationship between the pressure difference applied between both ends of an oil return passage at the time of oil return, and the flow velocity of the rising pipe part shown in FIG. It is a figure which shows the example of arrangement|positioning of the rising pipe part in the refrigerant circuit of the refrigerator which concerns on Embodiment 2.

An embodiment of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts will be denoted by the same reference numerals and description thereof will not be repeated.

Embodiment 1.
<Structure of refrigerator>
As shown in FIG. 1, the refrigerator 100 according to the first embodiment includes a refrigerant circuit forming a refrigeration cycle and an oil return passage connected to the refrigerant circuit.

The refrigerant circuit includes a compressor 1, a condenser 2, a first expansion device 3, an evaporator 4, and an oil separator 5. The refrigerant circuit is provided so that the refrigerant circulates through the compressor 1, the oil separator 5, the condenser 2, the first expansion device 3, and the evaporator 4 in order.

The compressor 1 includes a suction port for sucking the refrigerant, a compression unit for compressing the refrigerant sucked from the suction port, and a discharge port for discharging the high temperature/high pressure vapor-phase refrigerant compressed by the compression unit. The compression section is lubricated with refrigerating machine oil (hereinafter referred to as oil). The compressor 1 discharges the refrigerant and the refrigerating machine oil from the discharge port. Further, the compressor 1 sucks the refrigerant and the oil through the suction port. The discharge port of the compressor 1 is connected to the inflow port of the oil separator 5 via the first flow path 11 as the second refrigerant flow path. The suction port of the compressor 1 is connected to the outlet of the evaporator 4 via the fifth flow path 15 and the sixth flow path 16 as the first refrigerant flow path. Further, the suction port of the compressor 1 is connected to the oil return passage 17 via the sixth passage 16.

The oil separator 5 includes an inflow port into which the gas-phase refrigerant and oil flow, a first outflow port from which the gas-phase refrigerant flows out, and a second outflow port from which the oil flows out. The oil separator 5 is provided so as to separate the gas-phase refrigerant and the oil that have flowed in from the inflow port into the gas-phase refrigerant and the oil, and to each flow out from the first outflow port or the second outflow port. The first outlet of the oil separator 5 is connected to the inlet of the condenser 2 via the second flow passage 12. The second outlet of the oil separator 5 is connected to the oil return passage 17. Examples of the method for the oil separator 5 to separate the refrigerant and the oil include, but are not limited to, a cyclone method that uses centrifugal force and a demittas method that filters oil using a fine mesh.

The condenser 2 includes an inflow port into which the vapor phase refrigerant flowing out from the first outflow port of the oil separator 5 flows, and an outflow port from which the liquid phase refrigerant flows out. The condenser 2 is provided so that the gas-phase refrigerant flowing from the inflow port exchanges heat with the outside air. Thereby, the vapor phase refrigerant is condensed to become a liquid phase refrigerant. The outlet of the condenser 2 is connected to the inlet of the first expansion device 3 via the third flow path 13.

The first expansion device 3 includes an inlet through which the liquid-phase refrigerant condensed in the condenser 2 flows, and an outlet through which the gas-liquid 2 refrigerant flows out. The first expansion device 3 is provided so as to reduce the pressure of the liquid-phase refrigerant flowing from the inflow port. As a result, the liquid-phase refrigerant expands to become a gas-liquid two-phase refrigerant. The first expansion device 3 is provided, for example, as a capillary tube.

The evaporator 4 includes an inlet through which the gas-liquid two-phase refrigerant decompressed in the first expansion device 3 flows, and an outlet through which the gas phase refrigerant flows out. The evaporator 4 is provided so that the gas-liquid two-phase refrigerant that has flowed in through the inlet exchanges heat with the air in the storage chamber of the refrigerator 100. As a result, the gas-liquid two-phase refrigerant is evaporated and becomes a gas-phase refrigerant. The outlet of the evaporator 4 is connected to the suction port of the compressor 1 via the fifth flow passage 15 and the sixth flow passage 16. Further, the outlet of the evaporator 4 is connected to the oil return passage 17 via the fifth flow passage 15.

The fifth flow path 15 and the sixth flow path 16 connect the outflow port of the evaporator 4 and the suction port of the compressor 1. One end of the fifth flow path 15 in the refrigerant flow direction is connected to the outlet of the evaporator 4. The other end of the fifth flow path 15 in the flow direction is connected to one end of the sixth flow path 16. The other end of the sixth flow path 16 is connected to the suction port of the compressor 1. Further, the other end of the fifth flow passage 15 and the one end of the sixth flow passage 16 are connected to the oil return passage 17. The refrigerator 100 does not include an opening/closing valve that opens/closes the fifth flow path 15. A part of the fifth flow path 15 and the first expansion device 3 constitute, for example, the heat exchanger 8. The heat exchanger 8 is provided so that the refrigerant flowing through the first expansion device 3 and the refrigerant flowing through the fifth flow path 15 exchange heat with each other.

The oil return passage 17 is connected to the first end connected to the second outlet of the oil separator 5, the other end of the fifth flow passage 15 and the one end of the sixth flow passage 16. It has two ends. The second end of the oil return passage 17 is connected to a connecting portion 18 between the other end of the fifth flow passage 15 and the one end of the sixth flow passage 16. The oil return path 17 bypasses the condenser 2, the first expansion device 3, and the evaporator 4 in the refrigerant circuit, and connects the second outlet of the oil separator 5 and the inlet of the compressor 1 to each other. There is. The oil return passage 17 is provided to return the oil separated from the refrigerant by the oil separator 5 to the suction port of the compressor 1.

The oil return passage 17 includes the opening/closing valve 6 and the second expansion device 7. The on-off valve 6 is provided so as to open and close the oil return passage 17. The second expansion device 7 is provided so as to reduce the pressure of the oil flowing through the oil return passage 17. The open/close valve 6 is, for example, a solenoid valve. The on-off valve 6 is controlled to close the oil return passage 17 when the compressor 1 is driven and open the oil return passage 17 when the compressor 1 is stopped. The second expansion device 7 is, for example, a capillary tube.

As shown in FIG. 2, the refrigerator 100 is a machine in which at least the compressor 1, the oil separator 5, a part of the fifth flow path 15, the sixth flow path 16, and the oil return path 17 are housed. The chamber 21 and the heat insulating portion 22 that houses at least the remaining portion of the evaporator 4 and the fifth flow path 15 are provided. The heat insulating unit 22 is provided so as to surround a storage chamber (not shown) that is cooled by the evaporator 4. The heat insulating portion 22 has a portion arranged above the machine room 21.

<Fridge operation>
The refrigerator 100 has a first state in which the compressor 1 is driven and refrigerant is circulating in the refrigerant circuit, and a second state in which the compressor 1 is stopped and refrigerant is not circulating in the refrigerant circuit. It is provided to switch between states. The oil return passage 17 is closed by the opening/closing valve 6 in the first state and opened by the opening/closing valve 6 in the second state. The fifth flow path 15 is open in the first state and the second state.

In the first state, the refrigerant is the compressor 1, the first flow passage 11, the oil separator 5, the second flow passage 12, the condenser 2, the third flow passage 13, the first expansion device 3, the fourth flow passage. 14, the evaporator 4, the fifth flow path 15, and the sixth flow path 16 are sequentially circulated. Thereby, the refrigerator 100 can cool the air in the storage chamber.

When switching from the first state to the second state, the pressure difference between the first flow passage 11 and the sixth flow passage 16, that is, the pressure difference applied between both ends of the oil return passage 17 is the oil separator. Act on the oil separated in 5. The oil separated in the oil separator 5 in the first state flows through the oil return passage 17 due to the pressure difference after the second state is realized, and flows from the connection portion 18 to the fifth passage 15 and the fifth passage 15. 6 is returned to the flow path 16.

The gas-phase refrigerant evaporated in the evaporator 4 in the first state is stored in the fifth flow channel 15 and the sixth flow channel 16 in the second state. The pressure difference also acts on the vapor-phase refrigerant and oil in the fifth flow path 15. In the second state, the vapor-phase refrigerant and the oil in the fifth flow path 15 receive the pressure in the direction from the connecting portion 18 to the outlet of the evaporator 4. On the other hand, the fifth flow path 15 has a first rising pipe portion 31 described later. The first rising pipe portion 31 is provided so that gravity directed in the direction opposite to the pressure acts on the vapor-phase refrigerant and oil flowing through the first rising pipe portion 31 in the second state.
<Specific configuration of the first rising tube section>
FIG. 2 is a diagram for explaining the arrangement of the fifth flow path 15, the sixth flow path 16, and the oil return path 17 of the refrigerator 100 shown in FIG. The refrigerator 100 is arranged such that the Z direction shown in FIG. 2 is along the vertical direction. Note that, in FIG. 2, the illustration of the third flow path 13, the first expansion device 3, and the fourth flow path 14 illustrated in FIG. 1 is omitted.

As shown in FIG. 2, in the refrigerator 100, the evaporator 4 is arranged above the compressor 1 and the oil separator 5. The fifth flow path 15 has a first rising pipe portion 31 extending in the up-down direction. The lower end of the first rising pipe portion 31 constitutes, for example, the other end of the fifth flow passage 15, and is connected to the one end of the sixth flow passage 16 and the second end of the oil return passage 17. .. That is, the lower end of the first rising tube portion 31 is connected to the connecting portion 18, for example. The upper end of the first rising pipe portion 31 is arranged closer to the outlet of the evaporator 4 than the lower end of the first rising pipe portion 31 in the fifth flow path 15. The upper end of the first rising pipe portion 31 is arranged closer to the connecting portion 18 than the portion of the fifth flow path 15 forming the heat exchanger 8.

The sixth channel 16 has, for example, a second rising pipe portion 32 extending along the up-down direction. The upper end of the second rising pipe portion 32 constitutes, for example, the one end of the sixth flow passage 16, and is connected to the lower end of the first rising pipe portion 31 and the second end of the oil return passage 17. There is. The inner diameter of the pipe forming the sixth flow path 16 is equal to the inner diameter of the pipe forming the oil return passage, for example.

The first flow path 11 has, for example, a third rising pipe portion 33 extending along the up-down direction. The upper end of the third rising pipe portion 33 is connected to the inlet of the oil separator 5. The lower end of the third rising pipe portion 33 is connected to the discharge port of the compressor 1. The inner diameter of the third rising pipe portion 33 is equal to the inner diameter of the second rising pipe portion 32, for example.

As shown in FIG. 2, the first rising pipe portion 31 is provided only inside the machine room 21, for example. The fifth flow path 15 is surrounded by, for example, the heat insulating portion 22, and further includes a fourth rising pipe portion 34 extending in the up-down direction. The upper end of the first rising tube portion 31 is connected to the lower end of the fourth rising tube portion 34, for example.

The inner diameter of the first rising pipe portion 31 (first pipe portion) is larger than the inner diameter of the second rising pipe portion 32 (second pipe portion). That is, regarding the zero penetration speed Ug [unit: m/s] in the rising pipe section expressed by the following relational expression (1), the zero penetration speed Ug in the first rising pipe section 31 is equal to the second rising pipe section. Faster than zero penetration speed Ug at 32.

The manner in which the mixed fluid of the gas-phase refrigerant and oil rises can be regarded as the same as that of the gas-liquid two-phase refrigerant. Therefore, the zero penetration speed Ug applies the zero penetration speed defined in the upflow of the gas-liquid two-phase refrigerant to the upflow of the mixed fluid of the gas-phase refrigerant and the oil. In the relational expression (1), the inner diameter [unit: m] of the first rising pipe portion 31 or the rising pipe portion of the sixth flow path 16 is substituted for D. In the relational expression (1), g is gravitational acceleration 9.8 [unit: m/S ² ], ρl is oil density [unit: kg/m ³ ], and ρg is refrigerant gas density [unit: kg/m ^{3 ].} ], and Ug' is a constant. The method of calculating Ug' will be described later.

The inner diameter of the first rising tube portion 31 is larger than the inner diameter of the third rising tube portion 33. That is, regarding the zero penetration speed Ug [unit: m/s] in the rising pipe section represented by the above relational expression (1), the zero penetration speed Ug in the first rising pipe section 31 is equal to the third rising pipe section 33. Faster than the zero penetration speed Ug at.

The inner diameter of the first rising tube portion 31 is larger than the inner diameter of the fourth rising tube portion 34. That is, regarding the zero penetration speed Ug [unit: m/s] in the rising pipe section represented by the above relational expression (1), the zero penetration speed Ug in the first rising pipe section 31 is equal to the fourth rising pipe section 34. Faster than that.

The zero penetration speed Ug in the rising pipe portion extending along the vertical direction is the minimum flow velocity of the refrigerant required to raise the oil in the rising pipe portion when returning the oil. That is, the zero penetration speed Ug in the first rising pipe portion 31 is faster than the zero penetration speed Ug in the second rising pipe portion 32.

FIG. 3 is a graph showing the relationship between the inner diameter D of the rising pipe section expressed by the above relational expression (1) and the zero penetration speed Ug (zero penetration speed). The horizontal axis of FIG. 3 represents the zero penetration speed Ug (zero penetration speed) [unit: m/s], and the vertical axis of FIG. 3 represents the inner diameter D [unit: m]. As shown in FIG. 3, the larger the inner diameter D of the rising tube portion, the faster the zero penetration speed there.

Preferably, the inner diameter D [unit: m] of the first rising pipe portion 31 is equal to or less than the zero penetration speed Ug [unit: m/s] of the first rising pipe portion 31 calculated based on the above relational expression (1). It is provided so as to be faster than the flow velocity Ux [unit: m/s] calculated based on the relational expression (2). The flow velocity Ux is the flow velocity at the outlet of the evaporator 4 of the refrigerant flowing in the direction from the connecting portion 18 toward the outlet of the evaporator 4 due to the pressure difference when returning the oil.

In the relational expression (2), ΔP is the pressure difference [unit: MPa] between the first flow passage 11 and the sixth flow passage 16 when the compressor 1 is stopped, and ρg is the refrigerant gas density [unit. : Kg/m ³ ], h is the vertical distance (height difference) [unit: m] between the outlet of the evaporator 4 and the connecting portion 18.

FIG. 4 is a graph showing the relationship between the pressure difference ΔP and the flow velocity Ux expressed by the relational expression (2). The horizontal axis of FIG. 4 represents the pressure difference ΔP [unit: MPa], and the vertical axis of FIG. 4 represents the flow velocity Ux [unit: m/s]. As shown in FIG. 4, the larger the pressure difference ΔP, the faster the flow velocity Ux.

<Effect>
The refrigerator 100 includes the refrigerant circuit and the oil return passage 17. The refrigerant circuit includes a compressor 1, an oil separator 5, a condenser 2, a first expansion device 3, and an evaporator 4, and the refrigerant is a compressor 1, an oil separator 5, a condenser 2, a first expansion device. 3 and the evaporator 4 are sequentially circulated. The oil return passage 17 has a first end connected to the oil separator 5 and a second end connected between the evaporator 4 and the suction port of the compressor 1. It is provided so that the oil separated in (1) is returned to the suction port of the compressor 1. The refrigerant circuit has a fifth flow path 15 that connects between the evaporator 4 and the compressor 1. The fifth flow path 15 includes a connecting portion 18 connected to the oil return passage 17, and a first rising pipe portion 31 that is disposed closer to the evaporator 4 than the connecting portion 18 and extends in the up-down direction. Have The inner diameter of the first rising pipe portion 31 is larger than the inner diameter of the pipe forming the oil return passage 17.

In the refrigerator 100, since the fifth flow path 15 of the refrigerant circuit has the first rising pipe portion 31, the gravity acting on the vapor-phase refrigerant and the oil in the first rising pipe portion 31 reduces the gravity. In the 1 state, it is along the direction in which the refrigerant circulates. On the other hand, in the second state, the gravity acts on the pressure difference and acts in the direction opposite to the direction in which the refrigerant and the oil flow. Therefore, in the refrigerator 100, as compared with the conventional refrigerator in which the fifth flow path 15 does not have the first rising pipe portion 31, the refrigerant and the oil are less likely to rise in the first rising pipe portion 31 in the second state. , Oil is hard to reach the evaporator 4.

Further, in the refrigerator 100, since the inner diameter of the first rising pipe portion 31 is larger than the inner diameters of the pipe portions forming the sixth flow path 16 and the oil return passage 17, the zero penetration speed of the first rising pipe portion 31. However, it is faster than the zero penetration speed Ug in the rising pipe portion in the sixth flow passage 16 and the oil return passage 17, for example, in the second rising pipe portion 32. Therefore, in the refrigerator 100, as compared with the refrigerator in which the inner diameter of the first rising pipe portion 31 is equal to the inner diameters of the pipe portions forming the sixth flow path 16 and the oil return passage 17, the evaporator is more likely to be installed than the connection portion 18. The rise of oil is effectively suppressed in the first rising pipe portion 31 arranged near the position 4.

That is, even if the refrigerator 100 does not include an opening/closing valve that opens and closes the fifth flow passage 15, the refrigerator 100 includes the first rising pipe portion 31 and thus is returned from the oil return passage 17 to the fifth passage 15. It is possible to prevent the oil from flowing into the evaporator 4. Further, in the refrigerator 100, the on-off valve that opens and closes the fifth flow path 15 is not required, so chattering is suppressed and the manufacturing cost is further reduced as compared with the conventional refrigerator including the on-off valve. There is.

Further, in the refrigerator 100, the first rising pipe portion 31 is arranged only inside the machine room 21, and the first rising pipe portion 31 is not surrounded by the heat insulating portion 22. Therefore, in the refrigerator 100, like the refrigerator 101 described later, the inner diameter of the fourth rising pipe portion 34 surrounded by the heat insulating portion 22 is smaller than the inner diameters of the pipe portions forming the sixth flow passage 16 and the oil return passage 17. Can be easily manufactured as compared with the case where a large size is provided.

Preferably, the inner diameter of the first rising pipe portion 31 is provided so that the zero penetration speed Ug in the first rising pipe portion 31 becomes faster than the flow velocity Ux. Such a refrigerator 100 can more effectively suppress the oil subjected to the pressure difference from reaching the evaporator 4 via the first rising pipe portion 31.

The flow velocity Ux may be a flow velocity of the refrigerant flowing in the direction from the connecting portion 18 toward the outlet of the evaporator 4 due to the pressure difference during the oil return at the upper end of the first rising pipe portion 31. .. That is, h in the relational expression (2) may be a vertical distance (height difference) between the upper end of the first rising tube portion 31 and the connecting portion 18. The height difference between the upper end of the first rising pipe portion 31 and the connection portion 18 is less than the vertical distance (height difference) between the outlet of the evaporator 4 and the connection portion 18. Therefore, based on the relational expression (2), at the upper end of the first rising pipe portion 31 of the refrigerant flowing in the direction from the connection portion 18 toward the outlet of the evaporator 4 due to the pressure difference at the time of the oil return. The flow velocity becomes faster than the flow velocity of the refrigerant at the outlet of the evaporator 4. If the zero penetration speed of the first rising pipe portion 31 is set to be higher than the flow velocity of the refrigerant at the upper end of the first rising pipe portion 31, the oil becomes more difficult to reach the evaporator 4. ..

Embodiment 2.
As shown in FIG. 5, the refrigerator 101 according to the second embodiment has basically the same configuration as the refrigerator 100 according to the first embodiment, but the fifth flow path 15 has a plurality of rising

pipe portions

31, 34 to 40, and the inner diameters of the plurality of rising pipes are different from the inner diameters of the pipes forming the sixth flow passage 16 and the oil return passage 17. Note that in FIG. 5, the illustration of the third flow path 13, the first expansion device 3, and the fourth flow path 14 shown in FIG. 1 is omitted.

The fifth flow path 15 includes, for example, a first rising pipe portion 31, a fourth rising pipe portion 34, a fifth rising pipe portion 35, a sixth rising pipe portion 36, a seventh rising pipe portion 37, an eighth rising pipe portion 38, It has a ninth rising pipe portion 39 and a tenth rising pipe portion 40. The first rising pipe portion 31, the fourth rising pipe portion 34, the fifth rising pipe portion 35, the sixth rising pipe portion 36, the seventh rising pipe portion 37, the eighth rising pipe portion 38, the ninth rising pipe portion 39, and The tenth rising pipe portion 40 is sequentially connected to the outlet of the evaporator 4 from the connecting portion 18 in the fifth flow path 15.

Each of the plurality of rising

pipe portions

31, 34 to 40 extends in the vertical direction. The fourth rising pipe portion 34, the fifth rising pipe portion 35, the sixth rising pipe portion 36, the seventh rising pipe portion 37, the eighth rising pipe portion 38, the ninth rising pipe portion 39, and the tenth rising pipe portion 40 are It is arranged above the machine room 21 and is surrounded by the heat insulating portion 22. At least a part of the plurality of rising

pipe portions

31, 34 to 40 is arranged closer to the evaporator 4 than the portion of the fifth flow path 15 forming the heat exchanger 8.

The inner diameters of the plurality of rising

pipe portions

31, 34 to 40 are larger than the inner diameter of the second rising pipe portion 32. The inner diameters of the plurality of rising

pipe portions

31, 34 to 40 are larger than the inner diameter of the third rising pipe portion 33. The zero penetration velocities Ug of the plurality of rising

pipe portions

31, 34 to 40 are faster than those of the second rising pipe portion 32 and the third rising pipe portion 33.

Preferably, the inner diameter D [unit: m] of each of the plurality of rising

pipe portions

31, 34 to 40 is such that each zero penetration velocity Ug [unit: m/s] calculated based on the relational expression (1). It is provided so as to be faster than the flow velocity Ux [unit: m/s] calculated based on the relational expression (2). The inner diameters of the plurality of rising

tube portions

31, 34 to 40 are equal to each other, for example.

The fifth flow path 15 of the refrigerator 101 further includes, for example, in addition to the plurality of rising

pipe portions

31, 34 to 40, a horizontal pipe portion that extends in the horizontal direction. The inner diameters of the plurality of rising

pipe portions

31, 34 to 40 are larger than the inner diameter of the horizontal pipe portion, for example. The inner diameters of the plurality of rising

tube portions

31, 34 to 40 may be equal to the inner diameter of the horizontal tube portion, for example. That is, the entire fifth flow path 15 may be configured by a tube portion whose diameter is larger than that of the second rising tube portion 32.

Since the refrigerator 101 basically has the same configuration as the refrigerator 100, the same effect as the refrigerator 100 can be obtained.

Further, in the refrigerator 101, the inner diameter of each of the plurality of rising

pipe portions

31, 34 to 40 is set to be larger than the inner diameter of the second rising pipe portion 32, so that only the inner diameter of the first rising pipe portion 31 is Compared with the refrigerator 100 in which the inner diameter of the second rising pipe 32 is provided, it is possible to more effectively prevent the oil subjected to the pressure difference from reaching the evaporator 4 via the first rising pipe 31.

In the

refrigerators

100 and 101, the lower end of the first rising tube portion 31 is connected to the connecting portion 18, but the present invention is not limited to this. The fifth flow path 15 may further include another pipe portion that connects the lower end of the first rising pipe portion 31 and the connecting portion 18. In this case, the other tube portion may extend in any direction, and may extend in the up-down direction, for example. The inner diameter of the other tube portion may be any length, and may be equal to the inner diameter of the second rising tube portion 32, for example.

The embodiments of the present invention have been described above, but the above-described embodiments can be modified in various ways. Further, the scope of the present invention is not limited to the above embodiment. The scope of the present invention is shown by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

1 compressor, 2 condenser, 3 first throttle device, 4 evaporator, 5 oil separator, 6 on-off valve, 7 second throttle device, 11 first flow passage, 12 second flow passage, 13 third flow passage , 14, 4th flow passage, 15 5th flow passage, 16 6th flow passage, 17 oil return passage, 18 connection portion, 21 machine room, 22 heat insulation portion, 31 1st rising pipe portion, 32 2nd rising pipe portion, 33 3rd rising pipe part, 34 4th rising pipe part, 35 5th rising pipe part, 36 6th rising pipe part, 37 7th rising pipe part, 38 8th rising pipe part, 39 9th rising pipe part, 100 , 101 Refrigerator.

Claims

A refrigerant circuit including a compressor, an oil separator, a condenser, a throttle device, and an evaporator, and a refrigerant circuit in which a refrigerant circulates sequentially through the compressor, the oil separator, the condenser, the throttle device, and the evaporator. ,
The compressor includes a suction port and a discharge port, and is lubricated with refrigerating machine oil,
The refrigerant circuit has a first refrigerant flow path connecting between the evaporator and the suction port,
The oil separator is provided to separate the refrigerant discharged from the discharge port and the refrigerating machine oil,
Refrigerating machine oil having a first end connected to the oil separator and a second end connected to the first refrigerant flow path, and separated in the oil separator when the compressor stops driving. Further comprising an oil return passage provided to return the oil to the first refrigerant passage,
The first refrigerant flow passage is disposed between the connection portion connected to the second end of the oil return passage and the connection portion and the evaporator, and extends at least 1 in the vertical direction. A first pipe part and a second pipe part arranged between the connection part and the suction port,
The refrigerator in which the inner diameter of the at least one first pipe portion is larger than the inner diameter of the second pipe portion.
The refrigerator according to claim 1, wherein a lower end of the at least one first pipe part is connected to the connection part.
At least the compressor, the oil separator, and a machine room for accommodating the oil return passage, further comprising:
The refrigerator according to claim 1 or 2, wherein the at least one first pipe part is arranged only inside the machine room.
The at least one first tube portion has a plurality of first tube portions,
The refrigerator according to claim 1 or 2, wherein each inner diameter of the plurality of first pipe portions is larger than the inner diameter of the second pipe portion.
The refrigerant circuit has a second refrigerant flow path connecting the discharge port and the oil separator,
The second refrigerant flow path has a third tube portion extending along the vertical direction,
The refrigerator according to any one of claims 1 to 4, wherein an inner diameter of the at least one first pipe portion is larger than an inner diameter of the third pipe portion.
The oil return passage includes an on-off valve,
The on-off valve is provided so as to close the oil return passage when the compressor is driven and open the oil return passage when the compressor is stopped.
The evaporator is arranged above the connecting portion,
The inner diameter of the at least one first pipe portion is D, the gravitational acceleration is g, the density of the refrigerant is ρg, the density of the refrigerating machine oil is ρl, a constant Ug′, and the return passage is open. When the pressure difference acting between the first end and the second end of the oil return passage is ΔP, and the vertical distance between the evaporator and the connecting portion is h,
In order that the zero penetration speed Ug in the at least one first pipe portion calculated based on the following relational expression (1) becomes faster than the flow velocity Ux calculated based on the following relational expression (2), The refrigerator according to any one of claims 1 to 5, wherein the inner diameter D of the at least one first pipe portion is provided.