WO2016092771A1

WO2016092771A1 - Refrigeration cycle device

Info

Publication number: WO2016092771A1
Application number: PCT/JP2015/005962
Authority: WO
Inventors: 中村　毅; 英隆新開
Original assignee: 株式会社デンソー
Priority date: 2014-12-09
Filing date: 2015-12-01
Publication date: 2016-06-16
Also published as: JP2016109380A; JP6330641B2

Abstract

Provided is a refrigeration cycle device with which depletion of oil deficiency in a compressor can be avoided by means of a simple pipeline structure. This refrigeration cycle device is provided with a second pressure reduction device (22) connected in parallel to a first pressure reduction device (18), a second evaporator (20) connected to the second pressure reduction device, and a return-side connecting pipeline (42) connected to the intake side of the compressor. The second pressure reduction device has a throttle-forming portion (221a) in which a throttle hole (222c) is formed, a return-side passage (224) through which refrigerant outflowing from the second evaporator flows to the return-side connecting pipeline, and a hole opening adjustment mechanism (230) for making the hole opening of the throttle hole smaller in response to lower refrigerant temperature within the return-side passage, and reducing the pressure of the refrigerant inflowing to the second evaporator. A coupling part (424) of the return-side connecting pipeline has an upward passage (424b) communicating with the return-side passage, and extending farther upward than the return-side passage, so that in a state in which the flow of forced air for heat exchange with the refrigerant flowing through the second evaporator is halted, refrigerant entering the liquid phase state collects within the return-side passage.

Description

Refrigeration cycle equipment

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2014-249102 filed on Dec. 9, 2014, the disclosure of which is incorporated herein by reference.

The present disclosure relates to a piping structure of a refrigeration cycle apparatus having a plurality of evaporators provided in parallel.

A dual air conditioner is known as a vehicle air conditioner that uses this type of refrigeration cycle apparatus. The dual air conditioner has a front side evaporator that cools the blown air blown to the front side in the passenger compartment, and a rear side evaporator that cools the blown air blown to the rear side. In the refrigeration cycle apparatus of the dual air conditioner, as in the single air conditioner, oil for lubricating the inside of the compressor is mixed with the refrigerant and circulated.

In the dual air conditioner, there is a case where only the front side is operated, that is, the front side independent operation is performed in which the air is blown to the front side evaporator but the blowing to the rear side evaporator is stopped. Various configurations for avoiding oil shortage in the compressor due to oil stagnating in the rear refrigerant path during execution of the front side independent operation have been conventionally known.

For example, as one configuration for avoiding the shortage of oil, a configuration is known in which a solenoid valve is provided in a rear-side pipe for circulating a refrigerant to a rear-side evaporator. In this configuration, when the front-side independent operation is performed with the dual air conditioner, the inflow of refrigerant and oil to the rear-side evaporator is completely blocked by the electromagnetic valve. As a result, it is possible to prevent the oil from flowing into the rear side evaporator and the subsequent rear side low-pressure pipe and stagnating. However, in the configuration in which this electromagnetic valve is provided, the number of parts constituting the refrigeration cycle apparatus increases, which may lead to an increase in cost. In addition, the design may be complicated, for example, abnormal noise may occur if the solenoid valve is not controlled to open and close the solenoid valve.

Also, as another configuration, one that controls the operation of the compressor without providing the solenoid valve is known. That is, when a certain amount of time has elapsed since the start of the operation of the compressor during execution of the front side independent operation, intermittent compressor control is performed in which the compressor is intermittently turned on after being turned off. As a result, refrigerant pressure fluctuation occurs, and the refrigerant and oil accumulated in the rear-side evaporator and the rear-side low-pressure pipe can be returned to the compressor at once using the pressure fluctuation. However, it may take time to determine a control pattern for executing the compressor intermittent control, and cooling may be stopped while the compressor is OFF.

Also, for example, Patent Document 1 discloses a configuration that avoids oil shortage with a configuration different from the above configuration. In the vehicle dual air conditioner disclosed in Patent Document 1, the low-pressure pipe extending from the front-side evaporator is lowered downward, and the low-pressure pipe extending from the rear-side evaporator is pulled upward. Both of the low-pressure pipes are joined together so that the refrigerant flows at a position lower than that of the front-side evaporator. Furthermore, a low-pressure pipe extending from the junction where the two low-pressure pipes merge to the compressor side is pulled upward.

The refrigeration cycle apparatus included in the dual air conditioner for a vehicle of Patent Document 1 is said to be able to increase the circulation rate of oil to the compressor. In Patent Document 1, however, The relative positional relationship in the vertical direction and the direction of a plurality of low-pressure pipes connected to the merging portion are finely limited. That is, in order to realize the refrigeration cycle apparatus of Patent Document 1, there may be a very large restriction on piping.

Japanese Patent Laid-Open No. 11-20463

In view of the above points, it is an object of the present disclosure to provide a refrigeration cycle apparatus capable of avoiding oil shortage in a compressor with a simple piping structure.

According to one aspect of the present disclosure, the refrigeration cycle apparatus has a suction port, a compressor that compresses and discharges the refrigerant sucked from the suction port, a radiator that dissipates heat from the refrigerant discharged from the compressor, A first decompressor for decompressing the refrigerant flowing out of the radiator, a second decompressor connected to the radiator in parallel with the first decompressor for decompressing the refrigerant flowing out of the radiator, and an air conditioning first A first evaporator that is disposed in one air conditioning duct and evaporates by exchanging heat of the refrigerant decompressed by the first decompression device with the first blown air flowing in the first air conditioning duct; and a second air conditioning unit. A second evaporator, which is disposed in the air conditioning duct and evaporates by exchanging heat of the refrigerant decompressed by the second decompression device with the second blown air flowing in the second air conditioning duct, and flows out from the first evaporator. Flowing out of the second evaporator And a return-side connection pipe for guiding both medium to the suction port of the compressor. The second decompression device includes a throttle forming portion having a throttle hole, and a return side that is provided as a passage between the second evaporator and the return side connection pipe and flows the refrigerant flowing out of the second evaporator to the return side connection pipe. A return side passage forming portion in which a passage is formed, and a hole opening degree adjusting mechanism that reduces the opening degree of the throttle hole as the refrigerant temperature in the return side passage is lower. The hole opening adjustment mechanism depressurizes the refrigerant by restricting the refrigerant flow from the radiator to the second evaporator according to the decrease in the hole opening. The return side connection pipe has a connecting portion connected to the return side passage forming portion of the second pressure reducing device, and the connecting portion includes an upward passage communicating with the return side passage of the second pressure reducing device. The upward passage is more than the return-side passage so that the refrigerant becomes a liquid phase and accumulates in the return-side passage when the first blown air is blown while the second blown air is stopped. Extends upward.

According to the one aspect described above, the connecting portion of the return side connection pipe communicates with the return side passage of the second decompression device, and the first blown air is blown while the second blown air is stopped. In this state (hereinafter referred to as the first side operation state), an upward passage is formed extending upward from the return side passage so that the refrigerant enters a liquid phase state and accumulates in the return side passage. Therefore, in the first-side operation state, the return-side passage of the second decompression device can be filled with the refrigerant in the liquid phase state or almost the refrigerant in the gas-liquid mixed state. Therefore, the throttle hole of the second decompression device is fully closed (that is, the hole opening degree is zero) or substantially fully closed by the hole opening degree adjusting mechanism, and the refrigerant flow into the second evaporator is substantially stopped. Accordingly, oil can be prevented from flowing into the second evaporator by a simple piping structure in which an upward passage is provided, and occurrence of oil shortage in the compressor can be avoided.

It is a mimetic diagram showing the refrigerating cycle device in one embodiment of this indication. It is a figure which shows the II part in FIG.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments including other embodiments described later, the same or equivalent parts are denoted by the same reference numerals in the drawings.

FIG. 1 is a schematic diagram illustrating an overall configuration of a refrigeration cycle apparatus 10 according to an embodiment of the present disclosure. The arrows in the refrigerant passage illustrated in FIG. 1 and FIG. 2 described later indicate the refrigerant flow direction. As shown in FIG. 1, the refrigeration cycle apparatus 10 is provided in a dual air conditioner type vehicle air conditioner 8 having a plurality of

air conditioning units

12 and 14 for blowing conditioned air into a vehicle interior. The vehicle air conditioner 8 includes a front side air conditioning unit, that is, a front seat side air conditioning unit 12, and a rear side air conditioning unit, that is, a rear seat side air conditioning unit 14.

The front seat side air conditioning unit 12 is disposed inside the foremost instrument panel (not shown) in the passenger compartment, and air-conditions the area on the front seat side of the passenger compartment. The front seat side air conditioning unit 12 includes a front seat side air conditioning case 121 provided as a first air conditioning duct for air conditioning that forms an air passage, and a first air blower disposed upstream of the front seat side air conditioning case 121. It has a front seat side fan 122 as an apparatus. The front seat side air conditioning unit 12 includes a front seat side evaporator 16 and a front seat side expansion valve 18 that constitute a part of the refrigeration cycle apparatus 10.

A front seat side evaporator 16 as a first evaporator is accommodated in the front seat side air conditioning case 121, and the front seat side evaporator 16 is arranged on the downstream side of the air flow with respect to the front seat side blower 122. ing. The front seat evaporator 16 is a cooling heat exchanger that cools the first blown air flowing in the front seat side air conditioning case 121 as indicated by an arrow FL1a.

In addition, an air outlet 121 a is formed at the downstream end of the front seat air conditioning unit 12, that is, at the downstream end of the front seat air conditioning case 121 that forms the housing of the front seat air conditioning unit 12. The first blown air cooled by the front seat side evaporator 16 passes through the air outlet 121a as indicated by an arrow FL1b, and from the air outlet 121a, for example, the inner surface of the vehicle window glass, the head of the front seat side occupant The air is blown out toward any part of the passenger compartment such as the feet.

The rear seat side air conditioning unit 14 is arranged at the rear part of the vehicle interior, for example, at the side part of the rear seat so as to air-condition the rear seat side of the vehicle interior. The rear seat air conditioning unit 14 has the same configuration as the front seat air conditioning unit 12 described above.

Specifically, the rear seat side air conditioning unit 14 is disposed upstream of the rear seat side air conditioning case 141 provided as a second air conditioning duct for air conditioning that forms an air passage, and the rear seat side air conditioning case 141. A rear seat blower 142 or the like as the second blower is provided. Further, the rear seat side air conditioning unit 14 includes a rear seat side evaporator 20 and a rear seat side expansion valve 22 that constitute a part of the refrigeration cycle apparatus 10.

A rear seat side evaporator 20 as a second evaporator is accommodated in the rear seat side air conditioning case 141, and the rear seat side evaporator 20 is disposed on the downstream side of the air flow with respect to the rear seat side blower 142. Yes. The rear seat-side evaporator 20 is a cooling heat exchanger that cools the second blown air that flows in the rear seat-side air conditioning case 141 as indicated by an arrow FL2a.

Also, an air outlet 141 a is formed at the downstream end of the rear seat air conditioning unit 14, that is, at the downstream end of the rear seat air conditioning case 141 that forms the housing of the rear seat air conditioning unit 14. The second blown air cooled by the rear seat side evaporator 20 passes through the air outlet 141a as indicated by an arrow FL2b, and, for example, from the air outlet 141a toward the space around the rear seat in the vehicle interior. Blown out.

In the refrigeration cycle apparatus 10, a normal chlorofluorocarbon refrigerant is employed as the refrigerant. The refrigeration cycle apparatus 10 includes a subcritical refrigeration cycle in which the pressure of the high-pressure refrigerant does not exceed the critical pressure of the refrigerant.

As shown in FIG. 1, the refrigeration cycle apparatus 10 includes a compressor 30 (in addition to the front seat evaporator 16, the front seat expansion valve 18, the rear seat evaporator 20, and the rear seat expansion valve 22). COMP), a condenser 32, and

pipes

34, 36, 38, 40, 42, and the like. In the refrigeration cycle apparatus 10, the refrigerant discharged from the compressor 30 passes through the condenser 32, the front seat side expansion valve 18, and the front seat side evaporator 16 in this order, and returns to the compressor 30 in order. A refrigerant circuit, and a second refrigerant circuit for rear seat air conditioning in which the refrigerant discharged from the compressor 30 returns to the compressor 30 through the condenser 32, the rear seat expansion valve 22 and the rear seat evaporator 20 in order. Is configured. That is, the compressor 30 and the condenser 32 are included in both the first and second refrigerant circuits.

The compressor 30 has a suction port 30a and a discharge port 30b, compresses the refrigerant sucked from the suction port 30a, and discharges the compressed refrigerant, that is, a high-temperature and high-pressure refrigerant in a gas phase, from the discharge port 30b. For example, the compressor 30 is provided in an engine room of a vehicle and is driven by a vehicle engine (not shown).

The condenser 32 is an outdoor heat exchanger that is provided, for example, in a place where the traveling wind of the vehicle is easily received, and exchanges heat between the refrigerant flowing inside the condenser 32, the outside air blown by the outdoor fan, and the traveling wind. In other words, the condenser 32 is a radiator that radiates heat from the refrigerant discharged from the compressor 30.

Specifically, the refrigerant inlet 32 a of the condenser 32 is connected to the discharge port 30 b of the compressor 30 via the first high-pressure pipe 34, and the gas-phase refrigerant discharged from the compressor 30 is introduced into the condenser 32. The The condenser 32 condenses and liquefies the refrigerant discharged from the compressor 30 by heat exchange with the outside air.

The front seat side expansion valve 18 is an example of a first decompression device that decompresses the liquid-phase low-temperature refrigerant flowing out of the condenser 32. The rear seat side expansion valve 22 is connected in parallel to the front seat side expansion valve 18 with respect to the condenser 32, and is an example of a second decompression device that decompresses the low-temperature refrigerant in the liquid phase that has flowed out of the condenser 32. It has become.

Specifically, the refrigerant outlet 32b of the condenser 32 is connected to the front seat side expansion valve 18 through the second high-pressure pipe 36 and the third high-pressure pipe 38 connected to the downstream end of the second high-pressure pipe 36 in order. ing. At the same time, the refrigerant outlet 32b of the condenser 32 sequentially passes through the second high-pressure pipe 36 and the fourth high-pressure pipe 40 connected in parallel to the third high-pressure pipe 38 at the downstream end of the second high-pressure pipe 36. And connected to the rear seat side expansion valve 22. By connecting the high-

pressure pipes

36, 38, and 40, the liquid-phase refrigerant flowing out from the refrigerant outlet 32 b of the condenser 32 is introduced into the front seat side expansion valve 18 and the rear seat side expansion valve 22, respectively.

The front seat side expansion valve 18 and the rear seat side expansion valve 22 are well-known temperature type expansion valves and have the same internal structure. Therefore, the rear seat side expansion valve 22 enlarged in FIG. 2 will be mainly described, and the front seat side expansion valve 18 will be simplified by omitting the description common to the rear seat side expansion valve 22. .

FIG. 2 is a partial enlarged view in which the II part in FIG. 1 is enlarged and displayed. As shown in FIG. 2, the rear-seat side expansion valve 22 includes a forward-side passage forming part 221 in which a forward-side passage 222 that forms a part of the refrigerant forward path from the condenser 32 to the rear-seat evaporator 20 is formed; A return-side passage forming portion 223 in which a return-side passage 224 that forms a part of the refrigerant return path from the rear seat evaporator 20 to the suction port 30a of the compressor 30 is formed.

The forward passage 222 has a refrigerant inlet 222a and a refrigerant outlet 222b. The refrigerant inlet 222 a of the forward passage 222 is connected to the fourth high-pressure pipe 40, and the refrigerant outlet 222 b of the forward passage 222 is connected to the refrigerant inlet 20 a of the rear seat side evaporator 20.

Also, the return side passage 224 has a refrigerant inlet 224a and a refrigerant outlet 224b. The refrigerant inlet 224a of the return side passage 224 is connected to the refrigerant outlet 20b of the rear seat side evaporator 20, and the refrigerant outlet 224b of the return side passage 224 is connected to the second pipe 422 connected to the suction port 30a of the compressor 30. Has been. That is, the return side passage 224 is provided as a passage between the rear seat side evaporator 20 and the second pipe 422, and allows the refrigerant flowing out from the rear seat side evaporator 20 to flow to the second pipe 422.

In addition, the forward side passage 222 has a throttle hole 222c in the middle of the forward side passage 222 in which the passage cross section is reduced to restrict the refrigerant flow. That is, the forward side passage forming part 221 includes, as a part thereof, a throttle forming part 221a in which a throttle hole 222c is formed. The forward side passage forming portion 221 and the return side passage forming portion 223 are integrally formed with each other, and are included in, for example, an expansion valve main body 225 formed in a block shape made of an aluminum alloy.

Further, the rear seat side expansion valve 22 includes a valve body 226, a diaphragm operating portion 227, a temperature sensing rod 228, and an operating rod 229 in order to increase or decrease the opening degree of the throttle hole 222c. The valve body 226 is an open / close valve body that opens and closes the throttle hole 222 c, for example, has a spherical shape, and is disposed in the forward passage 222. The valve body 226 adjusts the opening degree of the throttle hole 222c according to the relative distance between the throttle hole 222c and the hole wall surface. The smaller the hole opening, the smaller the cross-sectional area of the refrigerant passage formed between the hole wall surface of the throttle hole 222c and the valve body 226, and the refrigerant flow passing through the throttle hole 222c is strongly throttled. In short, the throttle hole 222 c throttles the refrigerant flow from the condenser 32 to the rear seat side evaporator 20 according to the opening degree of the hole adjusted by the valve body 226. The throttle hole 222c expands the refrigerant passing through the throttle hole 222c under reduced pressure by narrowing the refrigerant flow. For example, the hole opening degree of zero is a fully closed state in which the throttle hole 222c is closed by the valve body 226.

The diaphragm operating part 227 is fixed to the upper end of the expansion valve body 225 by screws or the like. The diaphragm operating part 227 has a diaphragm 227a and forms a diaphragm chamber 227b in which a working gas is sealed. The working gas is, for example, the same type of saturated gas as the refrigerant used in the refrigeration cycle apparatus 10.

The diaphragm 227a is made of a thin metal plate having flexibility, for example. The diaphragm 227a forms a part of the diaphragm chamber 227b so as to close one surface of the diaphragm chamber 227b. Therefore, heat is transferred immediately if a temperature difference occurs between the working gas in the diaphragm chamber 227b and the diaphragm 227a. The diaphragm 227a is displaced according to the pressure change of the working gas in the diaphragm chamber 227b. In other words, the pressure of the working gas acts to expand the diaphragm chamber 227b and displace the diaphragm 227a downward as indicated by an arrow Pg.

The temperature sensing rod 228 is made of aluminum having high thermal conductivity, for example, and is a temperature sensing cylinder having a cylindrical shape. The temperature sensing rod 228 is disposed in the return side passage 224 such that the axial direction of the temperature sensing rod 228 intersects the refrigerant flow direction in the return side passage 224. That is, the temperature sensing rod 228 is disposed so as to cross a part of the return side passage 224 in the up-down direction DR1. The upper end of the temperature sensing rod 228 is in contact with the diaphragm 227a. With such an arrangement, the temperature sensing rod 228 transfers heat between the refrigerant in the return side passage 224 and the diaphragm 227a. Note that an arrow DR1 in FIG. 2 indicates the vertical direction DR1 of the rear seat side expansion valve 22 and a second pipe 422 to be described later.

The operating rod 229 has a cylindrical shape and functions as a valve operating unit that operates the valve body 226. The operating rod 229 is arranged in series with the temperature sensing rod 228 in the vertical direction DR1 and below the temperature sensing rod 228. The operating rod 229 is in contact with the lower end of the temperature sensing rod 228 at the upper end of the operation rod 229, and is connected to the diaphragm 227a via the temperature sensing rod 228. Further, the valve body 226 is connected to the lower end of the operating rod 229 so as to be displaced integrally with the operating rod 229 in the vertical direction DR1. Therefore, the actuating rod 229 operates the valve body 226 to the side where the opening degree of the throttle hole 222c is reduced as the diaphragm 227a is displaced (deformed) toward the side where the diaphragm chamber 227b is contracted (ie, the upper side).

Thus, the valve body 226, the diaphragm operating portion 227, the temperature sensing rod 228, and the operating rod 229 as a whole constitute a hole opening degree adjusting mechanism 230 that adjusts the opening degree of the throttle hole 222c. The hole opening adjusting mechanism 230 replaces the temperature change of the refrigerant in the return side passage 224 with a change in the opening degree of the throttle hole 222c by a mechanical operation, and the refrigerant temperature in the return side passage 224 is changed. The lower the aperture, the smaller the opening of the throttle hole 222c. Since the hole opening degree adjusting mechanism 230 operates in this way, for example, if the return side passage 224 is filled with the liquid phase refrigerant, the hole opening degree of the throttle hole 222c is made zero.

The front seat side expansion valve 18 shown in FIG. 1 is the same as the rear seat side expansion valve 22 described above, that is, the forward side passage forming portion 181 in which the forward side passage 182 including the throttle hole 182c for restricting the refrigerant flow is formed. And a return side passage forming portion 183 in which a return side passage 184 is formed.

The refrigerant inlet 182a of the forward passage 182 is connected to the third high-pressure pipe 38, and the refrigerant outlet 182b of the forward passage 182 is connected to the refrigerant inlet 16a of the front seat evaporator 16. Further, the refrigerant inlet 184a of the return side passage 184 is connected to the refrigerant outlet 16b of the front seat side evaporator 16, and the refrigerant outlet 184b of the return side passage 184 is connected to a suction port 30a of the compressor 30, which will be described later. 421.

Also, the front seat side expansion valve 18 has a hole opening degree adjusting mechanism 186 that adjusts the opening degree of the throttle hole 182c, similarly to the rear seat side expansion valve 22 described above.

The front seat side evaporator 16 is disposed in the front seat side air conditioning case 121 as shown in FIG. Low-pressure refrigerant decompressed by the throttle hole 182 c of the front seat side expansion valve 18 is introduced into the refrigerant inlet 16 a of the front seat side evaporator 16. The front seat evaporator 16 evaporates the low pressure refrigerant by exchanging heat with the air flowing in the front seat air conditioning case 121, and causes the low pressure refrigerant after the heat exchange to flow out of the refrigerant outlet 16b. The low-pressure refrigerant that has flowed out of the refrigerant outlet 16 b of the front seat side evaporator 16 flows into the first pipe 421 through the return side passage 184 of the front seat side expansion valve 18.

The rear seat evaporator 20 is disposed in the rear seat air conditioning case 141. Low-pressure refrigerant decompressed by a throttle hole 222c (see FIG. 2) of the rear seat side expansion valve 22 is introduced into the refrigerant inlet 20a of the rear seat side evaporator 20. The rear seat evaporator 20 evaporates the low pressure refrigerant by exchanging heat with the second blown air flowing in the rear seat air conditioning case 141, and causes the low pressure refrigerant after the heat exchange to flow out from the refrigerant outlet 20b. Then, the low-pressure refrigerant flowing out from the refrigerant outlet 20b of the rear seat side evaporator 20 flows into the second pipe 422 through the return side passage 224 (see FIG. 2) of the rear seat side expansion valve 22.

The refrigeration cycle apparatus 10 is provided with a low-pressure pipe 42 as an example of a return-side connection pipe that guides the refrigerant flowing out from the return-side passages 184 and 224 of the

expansion valves

18 and 22 to the suction port 30a of the compressor 30. Yes. The low pressure pipe 42 includes a first pipe 421, a second pipe 422, and a third pipe 423.

The upstream end of the first pipe 421 is connected to the refrigerant outlet 184 b of the return side passage 184 formed in the front seat side expansion valve 18, and the upstream end of the second pipe 422 is formed in the rear seat side expansion valve 22. The return side passage 224 is connected to the refrigerant outlet 224b. The downstream end of the first pipe 421 and the downstream end of the second pipe 422 are connected to the upstream end of the third pipe 423. That is, the first pipe 421 and the second pipe 422 are connected to the third pipe 423 in parallel with each other.

Further, the downstream end of the third pipe 423 is connected to the suction port 30a of the compressor 30. Accordingly, the refrigerant flowing out from the refrigerant outlet 184b of the return side passage 184 of the front seat side expansion valve 18 is guided to the suction port 30a of the compressor 30 through the first pipe 421 and the third pipe 423 in order. At the same time, the refrigerant flowing out from the refrigerant outlet 224b of the return side passage 224 of the rear seat side expansion valve 22 is guided to the suction port 30a of the compressor 30 through the second pipe 422 and the third pipe 423 in order. In short, the low-pressure pipe 42 guides the refrigerant flowing out from each of the front seat evaporator 16 and the rear seat evaporator 20 to the suction port 30 a of the compressor 30.

Here, as shown in FIG. 2, the second pipe 422 forming a part of the low-pressure pipe 42 has a connecting portion 424 that is connected to the return side passage forming portion 223 of the rear seat side expansion valve 22. In this connection portion 424, an inlet passage 424a and an upward passage 424b connected in series to the downstream side of the refrigerant flow of the inlet passage 424a are formed.

The upward passage 424b communicates with the return side passage 224 of the rear seat side expansion valve 22 via the inlet passage 424a. That is, the refrigerant outlet 224b of the return side passage 224 causes the refrigerant to flow out to the upward passage 424b.

The upward passage (rising passage) 424b extends (rises) obliquely upward with respect to the horizontal direction so that the downstream end 424d of the upward passage 424b in the refrigerant flow direction is positioned higher than the upstream end 424c. Specifically, the upward passage 424b is the uppermost portion of the return-side passage 224 of the rear seat side expansion valve 22 in which the lowermost portion 424e of the passage section SCt at the uppermost position of the upward passage 424b is located. It is provided so as to be positioned above the portion 224c. The horizontal direction may be perpendicular to the direction of gravity.

In the refrigerant path from the return side passage 224 to the upward passage 424b, it is desirable to prevent the vaporization of the refrigerant due to heat absorption from the outside air or the like. Accordingly, the passage length of the inlet passage 424a is very short, and the upward passage 424b extends upward immediately after the refrigerant outlet 224b of the return side passage 224.

In the refrigeration cycle apparatus 10 configured as described above, the operation state of the refrigeration cycle apparatus 10 is either the front / rear seat operation state as the first operation state or the front seat side single operation state as the second operation state. It becomes. The front and rear seat operation state of the refrigeration cycle apparatus 10 is an operation state when both the front seat air conditioning unit 12 and the rear seat air conditioning unit 14 shown in FIG. This is an operation state when the front seat air conditioning unit 12 is operating and the rear seat air conditioning unit 14 is stopped.

As shown in FIG. 1, in the front and rear seat operation state of the refrigeration cycle apparatus 10, the refrigerant discharged from the compressor 30 passes through the condenser 32, the front seat side expansion valve 18, and the front seat side evaporator 16 in order. The refrigerant circulates through the first refrigerant circuit for the front seat air conditioning that returns to 30. At the same time, the refrigerant discharged from the compressor 30 passes through the condenser 32, the rear seat side expansion valve 22, and the rear seat side evaporator 20 in that order and returns to the compressor 30 in the second refrigerant circuit for rear seat side air conditioning. Circulates. At this time, since both the front seat side air conditioning unit 12 and the rear seat side air conditioning unit 14 are operating, both the

fans

122 and 142 are blowing air. That is, in the front and rear seat operation state, the first blown air is blown by the front seat side blower 122 and the second blown air is also blown by the rear seat side blower 142. Therefore, in the front-rear seat operation state, the refrigerant is evaporated and vaporized by heat exchange with the air blown by the

blowers

122 and 142 in each of the front seat evaporator 16 and the rear seat evaporator 20.

In the front seat side independent operation state of the refrigeration cycle apparatus 10, the front seat side blower 122 blows air, but the rear seat side blower 142 is stopped. That is, in the front seat side independent operation state, the first blown air is blown while the second blown air is stopped. Therefore, in the front seat side independent operation state, heat exchange in the rear seat side evaporator 20 in the rear seat side air conditioning unit 14 is substantially stopped. As a result, the valve body 226 of the rear seat side expansion valve 22 makes the opening degree of the throttle hole 222c substantially zero, so that the refrigerant flow in the second refrigerant circuit is substantially stopped in the refrigeration cycle apparatus 10, and the refrigerant is exclusively used for the above. Circulate in the first refrigerant circuit.

Further, paying attention to oil as lubricating oil for lubricating the inside of the compressor 30, the oil is discharged from the discharge port 30b together with the refrigerant. And in the front-rear seat operation state of the refrigeration cycle apparatus 10, the oil goes around the first refrigerant circuit and the second refrigerant circuit together with the refrigerant and returns to the suction port 30 a of the compressor 30.

In the front seat side independent operation state of the refrigeration cycle apparatus 10, the refrigerant flowing out from the front seat side evaporator 16 in the first refrigerant circuit for front seat side air conditioning exchanges heat with the blown air of the front seat side blower 122 and performs superheat. It becomes. Therefore, the opening degree of the throttle hole 182c in the front seat side expansion valve 18 is increased, and the refrigerant in the front seat side evaporator 16 is a refrigerant that is large enough to cause the oil to flow out from the front seat side evaporator 16 together with the refrigerant. Flows at a flow rate. Therefore, in the first refrigerant circuit, the oil circulation rate at which the oil returns to the compressor 30 can be kept sufficiently large.

On the other hand, since the rear seat blower 142 is stopped in the front seat side independent operation state, the rear seat evaporator 20 does not exchange heat between the refrigerant and the air in the second refrigerant circuit for the rear seat air conditioning. The refrigerant flowing out of the rear seat side evaporator 20 is in a liquid phase state or almost a liquid phase gas-liquid mixed state.

Therefore, if the upward passage 424b of the low-pressure pipe 42 is not provided and the refrigerant in the return side passage 224 of the rear seat side expansion valve 22 returns to the compressor 30 without accumulating in the return side passage 224, The throttle hole 222c in the rear seat side expansion valve 22 opens to a certain extent although the opening is small. Then, the refrigerant flowing out from the rear seat evaporator 20 flows at a small refrigerant flow that is insufficient to cause the oil to flow out from the rear seat evaporator 20 together with the refrigerant, and the oil return amount to the compressor 30 in the second refrigerant circuit. Becomes scarce. As a result, in the entire refrigeration cycle apparatus 10, the amount of oil return to the compressor 30 is reduced.

On the other hand, in the refrigeration cycle apparatus 10 of the present embodiment, as shown in FIG. 2, an upward passage 424b is provided in the low-pressure pipe. Therefore, in the front seat side single operation state, the refrigerant in the liquid phase is blocked by the upward passage 424b and is accumulated in the return side passage 224 of the rear seat side expansion valve 22. Further, if the refrigerant flowing out from the rear seat side evaporator 20 is almost in a liquid phase gas-liquid mixed state, the liquid phase state refrigerant therein is blocked by the upward passage 424b. In other words, the upward passage 424b of the low-pressure pipe 42 extends upward from the return-side passage 224 so that the refrigerant is in a liquid state and accumulates in the return-side passage 224 in the front seat side single operation state.

In this way, in the front seat side independent operation state, the refrigerant in the liquid phase state or almost in the liquid phase gas-liquid mixture state is accumulated in the return side passage 224, so the state of the refrigerant in the return side passage 224 has no superheat. Then, the valve element 226 of the rear seat side expansion valve 22 makes the opening degree of the throttle hole 222c substantially zero. Accordingly, the refrigerant flow into the rear seat evaporator 20 is stopped or substantially stopped. As a result, in the second refrigerant circuit, the refrigerant in the liquid phase state or the almost liquid phase gas-liquid mixed state reaches the upward passage 424b from the throttle hole 222c of the rear seat side expansion valve 22 through the rear seat side evaporator 20. The oil stays in the refrigerant path, and oil inflow from the condenser 32 to the rear seat side expansion valve 22 can be prevented. And since a refrigerant | coolant circulates exclusively in the 1st refrigerant circuit for front seat side air conditioning, as a whole refrigeration cycle device 10, the oil circulation rate large enough to prevent oil shortage of compressor 30 can be maintained.

As described above, according to the present embodiment, the connecting portion 424 of the low pressure pipe 42 has the upward passage 424b that communicates with the return side passage 224 of the rear seat side expansion valve 22 and extends upward from the return side passage 224. Is formed. The upward passage 424b extends upward immediately after the refrigerant outlet 224b of the return side passage 224. That is, in the upward passage 424b, the refrigerant is in a liquid phase state in a state where the first blown air is blown and the second blown air is stopped (that is, the front seat side single operation state). And extends upward so as to accumulate in the return side passage 224. Therefore, in the front seat side independent operation state, the return side passage 224 of the rear seat side expansion valve 22 can be filled with the refrigerant in the liquid phase state or the refrigerant in the almost liquid phase gas-liquid mixed state.

Then, as described above, the opening degree of the throttle hole 222 c in the rear seat side expansion valve 22 is fully closed (that is, the hole opening degree is zero) or substantially fully closed by the valve body 226, and the rear seat side evaporator 20 is returned to. Inflow of refrigerant and oil almost stops. Therefore, the simple piping structure in which the upward passage 424b is provided in the low-pressure pipe 42 can prevent the oil from flowing into the rear seat side evaporator 20, and the occurrence of oil shortage in the compressor 30 can be avoided. Note that filling the return side passage 224 with almost liquid phase gas-liquid mixed refrigerant means that the return side passage 224 is filled with liquid phase refrigerant and a slight amount of gas phase refrigerant. Therefore, also in this case, the refrigerant is in a liquid phase state and is accumulated in the return side passage 224.

Further, in the front seat side single operation state of the refrigeration cycle apparatus 10, the inflow of refrigerant and oil to the rear seat side evaporator 20 substantially stops as described above. Therefore, there is an advantage that it is not necessary to execute the above-described intermittent compressor control for performing the intermittent operation of the compressor 30 in order to return the oil from the rear seat evaporator 20 to the compressor 30.

Further, according to the present embodiment, the upward passage 424b of the low-pressure pipe 42 extends obliquely upward with respect to the horizontal direction, and therefore, for example, compared to a case where it extends vertically to the horizontal direction, the rear seat During the operation of the side air conditioning unit 14, the refrigerant can flow smoothly into the upward passage 424b.

Further, according to the present embodiment, the upper passage 424b of the low-pressure pipe 42 is such that the lowermost portion 424e in the passage section SCt (see FIG. 2) at the uppermost position of the upward passage 424b is the rear seat side expansion valve 22. In the return side passage 224, the uppermost portion 224c located on the uppermost side is provided above the uppermost portion 224c. Therefore, in the front seat side single operation state of the refrigeration cycle apparatus 10, it is possible to dam the refrigerant in the upward passage 424b so that the return-side passage 224 is filled with the liquid-phase refrigerant.

In the above-described embodiment, the inlet passage 424a is provided in the connecting portion 424 of the second pipe 422 in FIG. 2, but even if the inlet passage 424a is not present or is extremely short to the extent that there is no inlet passage 424a. Good. In that case, the upward passage 424b is provided extending upward from the refrigerant outlet 224b of the return side passage 224 of the rear seat side expansion valve 22. If so, the refrigerant blocked by the upward passage 424b as compared with the case where the inlet passage 424a having a certain length is provided between the return side passage 224 and the upward passage 424b. It is possible to suppress the heat absorption of the refrigerant and to prevent evaporation of the refrigerant.

In the above-described embodiment, the vehicle air conditioner 8 includes the two

air conditioning units

12 and 14, but may include three or more air conditioning units.

Note that the present disclosure is not limited to the above-described embodiment, and can be changed as appropriate. Further, in the above-described embodiment, it is needless to say that elements constituting the embodiment are not necessarily indispensable except for the case where it is clearly indicated that the element is essential and the case where the element is clearly considered to be essential in principle. . Further, in the above embodiment, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is particularly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to a specific number except for cases. Further, in the above embodiment, when referring to the material, shape, positional relationship, etc. of the component, etc., unless otherwise specified and in principle limited to a specific material, shape, positional relationship, etc. The material, shape, positional relationship and the like are not limited.

Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims

A compressor (30) having a suction port (30a) for compressing and discharging the refrigerant sucked from the suction port;
A radiator (32) for radiating heat from the refrigerant discharged by the compressor;
A first decompression device (18) for decompressing the refrigerant flowing out of the radiator;
A second decompression device (22) connected in parallel to the first decompressor for the radiator and decompressing the refrigerant flowing out of the radiator;
The refrigerant which is disposed in the first air conditioning duct (121) for air conditioning and evaporates by exchanging heat with the first blown air flowing in the first air conditioning duct. One evaporator (16),
The refrigerant which is disposed in the second air conditioning duct (41) for air conditioning and evaporates by exchanging heat with the second blown air flowing through the second air conditioning duct. Two evaporators (20);
A return side connection pipe (42) for guiding both the refrigerant flowing out of the first evaporator and the refrigerant flowing out of the second evaporator to the suction port of the compressor;
The second pressure reducing device is provided as a passage between a throttle forming portion (221a) having a throttle hole (222c) and the second evaporator and the return side connection pipe, and flows out from the second evaporator. A return-side passage forming portion (223) having a return-side passage (224) for flowing the refrigerant to the return-side connecting pipe, and a hole for reducing the opening degree of the throttle hole as the refrigerant temperature in the return-side passage decreases. An opening adjustment mechanism (230),
The hole opening adjustment mechanism depressurizes the refrigerant by restricting a refrigerant flow from the radiator to the second evaporator according to a decrease in the hole opening;
The return side connection pipe has a connecting portion (424) connected to a return side passage forming portion of the second decompression device,
The connecting portion includes an upward passage (424b) communicating with the return-side passage of the second decompression device,
The upward passage is arranged so that the refrigerant becomes a liquid phase and accumulates in the return side passage in a state where the first blowing air is blown and the second blowing air is stopped. A refrigeration cycle apparatus extending upward from the return side passage.
The return side passage has a refrigerant outlet (224b) for letting the refrigerant flow out to the upward passage,
The refrigeration cycle apparatus according to claim 1, wherein the upward passage extends upward from a refrigerant outlet of the return side passage.
The refrigeration cycle apparatus according to claim 1 or 2, wherein the upward passage extends obliquely upward with respect to a horizontal direction.
In the upward passage, the lowermost portion (424e) of the passage section (SCt) of the upward passage at the uppermost position of the upward passage is the uppermost portion (224c) of the return side passage. The refrigeration cycle apparatus according to any one of claims 1 to 3, which is located above the position.
The hole opening degree adjusting mechanism of the second pressure reducing device closes the valve body (226) for adjusting the hole opening degree of the throttle hole, the diaphragm chamber (227b) filled with the working gas, and one surface of the diaphragm chamber. A diaphragm actuating portion (227) having a diaphragm (227a); a temperature sensing rod (228) disposed in the return side passage for transferring heat between the refrigerant in the return side passage and the diaphragm; A valve operating part (229) connected to the diaphragm via a hot rod,
The said valve action part operates the said valve body so that the opening degree of the said throttle hole may become so small that the said diaphragm deform | transforms so that the said diaphragm chamber may shrink | contract. Refrigeration cycle equipment.