JP6522295B2 - Refrigeration system - Google Patents

Description

  The present invention relates to a refrigeration system that executes a refrigeration cycle, for example, to a refrigeration system that uses an HFO (hydrofluoroolefin) refrigerant.

  In the field of refrigeration equipment, ozone layer destruction by refrigerants and global warming are raised as problems, and consumption control of refrigerants having ozone layer destruction coefficients, substitution of refrigerants with high global warming potential (GWP), or refrigerant leakage Each factor is being considered, including measures to prevent In particular, HFO-1234yf (2,3,3,3-tetrafluoro-1-propene) is considered promising as an alternative refrigerant for automobile air conditioning.

  HFO refrigerants tend to have low high-pressure gas temperatures due to their physical properties, and the degree of superheat of the refrigerant discharged from the compressor tends to be small, thereby causing the refrigerant drawn into the compressor to be wet. If so, the reliability of the compressor due to liquid compression will be impaired. In order to avoid this, the refrigerant may be sufficiently overheated and then drawn into the compressor. However, if the refrigerant is overheated in the heat exchanger provided in the refrigeration system, the capacity of the heat exchanger may be reduced, Dehumidification performance deterioration at the time of cooling may cause condensation on the fan attached to the heat exchanger, which may cause a problem of causing water splash.

Therefore, Patent Document 1 proposes providing a refrigeration system with a superheating mechanism that overheats the refrigerant sent from the evaporator to the compressor. This superheating mechanism heats the refrigerant sent from the evaporator to the compressor by the refrigerant sent from the radiator (condenser) to the expansion mechanism.
According to the proposal of Patent Document 1, the refrigerant to be sucked into the compressor is prevented from becoming wet by heating the refrigerant sent from the evaporator to the compressor by the superheating mechanism. It can avoid that liquid compression arises. Since patent document 1 heats a refrigerant | coolant by a superheating mechanism, it does not exert a bad influence on the capability of a heat exchanger or the dehumidification performance at the time of air conditioning.

JP, 2009-222348, A

However, since the temperature of the refrigerant sent from the radiator to the expansion mechanism is low, there is a possibility that the proposal of Patent Document 1 can not provide sufficient overheating to the refrigerant sent from the evaporator to the compressor.
Then, an object of the present invention is to provide a refrigerator which can give sufficient superheat to the refrigerant sent to a compressor from an evaporator.

With such a purpose, the refrigeration apparatus of the present invention comprises a compressor for compressing a refrigerant, a condenser for causing a refrigerant compressed by the compressor to radiate and condense, and an expansion mechanism for reducing the pressure of the refrigerant condensed in the condenser. And an evaporator for evaporating the refrigerant decompressed in the expansion mechanism are connected to form a circulation circuit of the refrigerant, and the evaporator and the compressor are provided in parallel to the main circuit, And heating the refrigerant evaporated in the heat exchange with the refrigerant flowing through the condenser and returning the refrigerant to the main circuit.
Since the refrigeration system of the present invention exchanges heat between the refrigerant flowing in the condenser into which the high-temperature refrigerant is introduced and the refrigerant evaporated in the evaporator, the refrigerant evaporated in the evaporator can be sufficiently superheated.

In the refrigeration apparatus of the present invention, the normal operation in which the refrigerant evaporated in the evaporator is drawn into the compressor via the main circuit, and the refrigerant evaporated in the evaporator are transmitted to the main circuit via the superheat circuit. It is possible to provide an operation switching mechanism that selectively performs an overheat operation to be sucked into the compressor after being returned.
According to this refrigeration system, since the normal operation and the overheat operation are switched, operation control according to the heat load is possible.

In the refrigeration apparatus of the present invention, the operation switching mechanism can switch the normal operation and the overheat operation depending on the state of one or both of the refrigerant sucked into the compressor and the refrigerant discharged from the compressor.
According to this refrigeration apparatus, since the normal operation and the overheat operation are switched according to the state of the refrigerant, the operation can be switched at an appropriate timing.

  In the refrigeration apparatus of the present invention, it is preferable that the superheating circuit includes a heat exchanger that receives the heat radiation of the refrigerant via the condenser and overheats the refrigerant returned to the main circuit in order to efficiently perform the superheating.

In the refrigeration system according to the present invention, the room functions as a condenser during cooling operation, and as an outdoor heat exchanger functioning as an evaporator during heating operation, and functions as an evaporator during cooling operation, and also functions as a condenser during heating operation. a heat exchanger, Ru equipped with. In the refrigeration system used by switching between cooling and heating, the heating circuit functions as a first heating circuit that collects heat from an outdoor heat exchanger that functions as a condenser during cooling operation, and functions as a condenser during heating operation. a condensing heat second heating circuit from the indoor heat exchanger, Ru equipped with.
According to this refrigeration apparatus, in the apparatus capable of switching and operating between cooling and heating, the refrigerant evaporated by the evaporator can be superheated both in the cooling operation and the heating operation.

  According to the present invention, the refrigerant evaporated in the evaporator and the refrigerant flowing through the condenser into which the high temperature refrigerant is introduced are heat exchanged, so that the refrigerant evaporated in the evaporator can be sufficiently superheated.

It is a figure which shows the circuit structure of the freezing apparatus which concerns on 1st Embodiment of this invention. 1 shows the flow of the refrigerant when operating the refrigeration system of FIG. 1 as cooling, where (a) shows a normal operation without the refrigerant being overheated, and (b) shows an overheat operation with the refrigerant overheated. . 1 shows the flow of the refrigerant when the refrigeration system of FIG. 1 is operating as heating, where (a) shows a normal operation without the refrigerant being overheated, and (b) shows an overheat operation with the refrigerant overheated. . An arrangement example of the superheating heat exchanger in the refrigerating apparatus of FIG. 1 is shown, (a) shows an example arranged downwind from the condenser, and (b) shows an example arranged upwind from the condenser. It is a figure which shows the circuit structure of the freezing apparatus which concerns on 2nd Embodiment of this invention. FIG. 6 shows the flow of the refrigerant when the refrigeration system of FIG. 5 is operating (as cooling), in which (a) shows the normal operation without the refrigerant being overheated, and (b) shows the superheating operation with the refrigerant overheated. Indicates An arrangement example of the superheating heat exchanger in the refrigeration apparatus of FIG. 5 is shown, (a) shows an example arranged downwind from the condenser, and (b) shows an example arranged upwind from the condenser.

First Embodiment
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
As shown in FIG. 1, the refrigeration apparatus 1 according to the first embodiment includes a compressor 10, an outdoor heat exchanger 13, an expansion valve 15, an indoor heat exchanger 16, and a four-way valve 18. A main circuit that executes the refrigeration cycle is configured.
The refrigeration apparatus 1 is premised on using HFO refrigerant as a refrigerant, and includes a first heating circuit 20 and a second heating circuit 30 in addition to the main circuit, and the first heating circuit 20 or the second heating circuit 30 is operated. As a result, the refrigerant drawn into the compressor 10 is overheated. This embodiment is an apparatus which performs a refrigeration cycle using a single refrigerant consisting of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene) as the HFO refrigerant. Here, HFO-1234yf _is represented by the chemical formula CF 3 -CF = CH _2.
Hereinafter, the configuration of the refrigeration system 1, the operation and effects of the refrigeration system 1 will be described in order.

[Configuration of refrigeration system 1]
The configuration of the main circuit is as follows.
The compressor 10 is connected to one end of a refrigerant pipe L1 to which the compressed high-temperature, high-pressure refrigerant (gas) is discharged. The other end of the refrigerant pipe L1 is connected to the first port P1 of the four-way valve 18. The four-way valve 18 is provided with a first port P1 to a fourth port P4 and four ports, and switches the internal flow path according to the cooling operation and the heating operation of the refrigeration apparatus 1.
One end of a refrigerant pipe L2 is connected to the second port P2 of the four-way valve 18. The other end of the refrigerant pipe L2 is connected to the outdoor heat exchanger 13.
One end of a refrigerant pipe L9 is connected to the third port P3 of the four-way valve 18. The other end of the refrigerant pipe L9 is connected to the suction side of the compressor 10.
One end of a refrigerant pipe L4 is connected to the fourth port P4 of the four-way valve 18. The other end of the refrigerant pipe L4 is connected to the indoor heat exchanger 16.
One end of a refrigerant pipe L3 is connected to the outdoor heat exchanger 13, and the other end of the refrigerant pipe L3 is connected to the indoor heat exchanger 16. The refrigerant pipe L3 is provided with an expansion valve 15, and adiabatically expands the refrigerant passing through the refrigerant pipe L3.

  The compressor 10 is a device that compresses a refrigerant, and any of a sealed compressor that performs a compression operation with an external drive source and a sealed compressor that incorporates a drive motor can be applied. Also, there is no restriction on the method of the compression mechanism, and either a rotary type or a scroll type can be applied. Further, although an example in which one compressor 10 is used is shown here, a plurality of compressors 10 can be connected in parallel and used.

  The outdoor heat exchanger 13 is configured as an air heat exchanger that exchanges heat between the refrigerant passing therethrough and the outdoor air, and for example, a fin-and-tube type heat exchanger is applied. The outdoor heat exchanger 13 is provided with an outdoor fan 14 so that the outdoor air sucked by operating the outdoor fan 14 passes through the outdoor heat exchanger 13 by blowing air, thereby allowing the outdoor air to flow. Exchange heat between the refrigerant and the refrigerant.

  The indoor heat exchanger 16 is configured as an air heat exchanger that performs heat exchange between indoor air and a refrigerant, and a fin and tube type heat exchanger, for example, is applied. The indoor heat exchanger 16 is provided with an indoor fan 17 so that the indoor air sucked by operating the indoor fan 17 passes through the indoor heat exchanger 16 by blowing the air through the room air. Exchange heat between the refrigerant and the refrigerant.

  The expansion valve 15 is a mechanism that decompresses the refrigerant sent from the outdoor heat exchanger 13 to the indoor heat exchanger 16 during the cooling operation, and for example, an electronic expansion valve is applied.

  In the refrigeration system 1 having the above-described main circuit configuration, the refrigerant pipe L1, the four-way valve 18, the refrigerant pipe L2, the outdoor heat exchanger 13, and the high-temperature and high-pressure refrigerant discharged from the compressor 10 during the cooling operation. The refrigerant pipe L 3, the indoor heat exchanger 16, the refrigerant pipe L 4, the four-way valve 18, and the refrigerant pipe L 9 are sequentially passed through and drawn into the compressor 10. In the heating operation, the high temperature and high pressure refrigerant discharged from the compressor 10 is the refrigerant pipe L1, the four-way valve 18, the refrigerant pipe L4, the indoor heat exchanger 16, the refrigerant pipe L3, the outdoor heat exchanger 13, The refrigerant pipe L2, the four-way valve 18, and the refrigerant pipe L9 pass in this order, and are drawn into the compressor 10. However, when the first heating circuit 20 or the second heating circuit 30 described below operates, a part of the flow of the refrigerant is changed.

  The first overheat circuit 20 functions during the cooling operation, and as shown in FIG. 1, the first overheat heat exchanger 21, one end thereof is connected to the first overheat heat exchanger 21, and the other end is the refrigerant pipe L4. And a refrigerant pipe L6, one end of which is connected to the first overheat heat exchanger 21 and the other end of which is connected to the refrigerant pipe L4, and the refrigerant pipe L4, the refrigerant pipe L5, and the first overheat heat exchanger 21 are provided. And refrigerant circulation circuit is constituted by refrigerant piping L6.

  The first overheat heat exchanger 21 is provided in proximity to the outdoor heat exchanger 13 and exchanges heat with the refrigerant flowing through the outdoor heat exchanger 13 in the process of passing the refrigerant, whereby the first superheated heat exchanger 21 is sucked into the compressor 10. The refrigerant that is being The first superheated heat exchanger 21 is composed of a fin-and-tube type heat exchanger. The same applies to a second superheated heat exchanger 31 described later.

The first superheating circuit 20 is on the refrigerant pipe L4, and is provided between the connection part of the refrigerant pipe L5 and the refrigerant pipe L4 and between the connection part of the refrigerant pipe L6 and the refrigerant pipe L4, and the refrigerant pipe L5. An on-off valve V2 is provided on the top. The first heating circuit 20 also includes a check valve V5 on the refrigerant pipe L6. The check valve V5 allows the flow of the refrigerant from the first overheat heat exchanger 21 toward the refrigerant pipe L4, but the reverse, that is, the flow of the refrigerant from the refrigerant pipe L4 toward the first overheat heat exchanger 21 Stop it.
The first overheat circuit 20 pulls the refrigerant into the circulation circuit by controlling the opening and closing of the on-off valve V1 and the on-off valve V2, thereby preventing the refrigerant from being drawn into the circulation circuit. Either of the normal operation is selectively performed. This selection is handled by the controller 50, as will be described later.

The first overheat heat exchanger 21 is disposed in proximity to the outdoor heat exchanger 13 so as to be able to exchange heat with the outdoor heat exchanger 13. Specifically, as shown in FIG. 4 (a), based on the direction A of the outdoor air blown by the outdoor fan 14, the downstream side of the outdoor heat exchanger 13 or as shown in FIG. 4 (b) The first overheat heat exchanger 21 can be disposed upstream of the outdoor heat exchanger 13. Since the air around the outdoor heat exchanger 13 is warmed to, for example, 40 to 50 ° C. by heat radiation from the refrigerant, whether it is downstream or upstream, the refrigerant passing through the first superheated heat exchanger 21 is heated be able to. In the case where the first overheat heat exchanger 21 is provided on the downstream side shown in FIG. 4A, the air warmed by passing through the outdoor heat exchanger 13 passes through the first overheat heat exchanger 21. In the case where the first overheat heat exchanger 21 is provided on the upstream side shown in FIG. 4B, the air before being sucked into the outdoor heat exchanger 13 passes through the first overheat heat exchanger 21.
This arrangement can be similarly applied to the arrangement position of the second superheating heat exchanger 31 with respect to the indoor heat exchanger 16.

  The second overheat circuit 30 functions during heating operation, and as shown in FIG. 1, the second overheat heat exchanger 31, one end is connected to the second overheat heat exchanger 31, and the other end is the refrigerant pipe L2 And a refrigerant pipe L8 having one end connected to the second overheat heat exchanger 31 and the other end connected to the refrigerant pipe L2, and the refrigerant pipe L2, the refrigerant pipe L7, and the second overheat heat exchanger 31 are provided. And refrigerant circulation circuit is constituted by refrigerant piping L8.

  The second superheated heat exchanger 31 is provided in the vicinity of the indoor heat exchanger 16 and exchanges heat with the refrigerant flowing through the indoor heat exchanger 16 in the process of passing the refrigerant, whereby the second superheated heat exchanger 31 is sucked into the compressor 10. The refrigerant that is being

The second superheat circuit 30 is on the refrigerant pipe L2, and is provided between the connection part of the refrigerant pipe L7 and the refrigerant pipe L2, and between the connection part of the refrigerant pipe L8 and the refrigerant pipe L2, and the refrigerant pipe L7. An on-off valve V4 is provided on the top. The second heating circuit 30 also includes a check valve V6 on the refrigerant pipe L8. The check valve V6 allows the flow of the refrigerant from the second overheat heat exchanger 31 toward the refrigerant pipe L2, but the reverse, that is, the flow of the refrigerant from the refrigerant pipe L2 toward the second overheat heat exchanger 31 Stop it.
The second overheat circuit 30 pulls the refrigerant into the circulation circuit by controlling the opening and closing of the on-off valve V3 and the on-off valve V4, thereby preventing the refrigerant from being drawn into the circulation circuit. Either of the normal operation is selectively performed.

The refrigeration system 1 includes a controller 50 that controls the operation of the refrigeration system 1.
Specifically, operation and stop of the compressor 10, the outdoor fan 14 and the indoor fan 17, the opening degree of the expansion valve 15, and the flow path switching of the four-way valve 18 are controlled. Further, the controller 50 controls the opening and closing operation of the on-off valves V1 to V4 provided in the first heating circuit 20 and the second heating circuit 30.
The controller 50 detects the temperature (T) of the refrigerant compressed by the compressor 10 by the temperature sensor S attached to the refrigerant pipe L1. The controller 50, by comparing the temperature T and the threshold temperature T _R which has detected, to control the opening and closing operation of the opening and closing valve V1-V4.

[Operation of refrigeration system 1]
Next, with regard to the operation of the refrigeration system 1, the cooling operation will be described in the order of the heating operation with reference to FIG. 3 with reference to FIG. The description of the controller 50 and the temperature sensor S is omitted in FIG.
The refrigeration apparatus 1 can overheat the refrigerant by causing the first heating circuit 20 or the second heating circuit 30 to function while performing the cooling operation or the heating operation.
In the present specification, “high pressure” means high pressure in the refrigeration cycle, and “low pressure” means low pressure in the refrigeration cycle. Moreover, the white arrow of FIG. 2, FIG. 3 has shown the direction into which the refrigerant | coolant flows. The same applies to FIG.

[Cooling operation]
The cooling operation includes a normal operation (FIG. 2 (a)) in which the refrigerant is not drawn into the circulation circuit and an overheat operation (FIG. 2 (b)) in which the refrigerant is drawn into the circulation circuit of the first heating circuit 20. This will be described in this order. In addition, the refrigeration apparatus 1 can switch from the normal operation to the overheat operation or switch from the overheat operation to the normal operation according to an instruction from the controller 50. If the temperature T of the refrigerant detected by the temperature sensor S exceeds the threshold temperature T _R , the controller 50 controls the opening and closing of the on-off valves V1 to V4 to perform the normal operation (T _R <T). controls the opening and closing of the threshold temperature _T if _R less normal operation _{(T R} ≧ T) so as to open and close valves V1-V4.

[Normal operation: Fig. 2 (a)]
In the refrigeration system 1, during the cooling operation, the first port P1 and the second port P2 of the four-way valve 18 are connected, and the third port P3 and the fourth port P4 are connected. That is, during the cooling operation, the refrigerant pipe L1 and the refrigerant pipe L2 are connected, and the refrigerant pipe L4 and the refrigerant pipe L9 are connected.
Moreover, the states of the open (ON) and closed (OFF) states of the on-off valves V1 to V4 of the first heating circuit 20 and the second heating circuit 30 are as follows. In FIG. 2, the open / close valves V1 to V4 are shown in white, and the closed valves V1 to V4 are shown in black. The same applies to FIG. 3 and FIG.
V1: Open (ON) V2: Closed (OFF) V3: Closed (OFF) V4: Open (ON)

Now, when the compressor 10 is operated, the high-temperature and high-pressure refrigerant (gas) compressed by the compressor 10 is discharged to the refrigerant pipe L1, passes through the four-way valve 18, and flows through the refrigerant pipe L2. Since the on-off valve V3 is open, the high-temperature and high-pressure refrigerant flows into the outdoor heat exchanger 13, dissipates heat to the outdoor air blown by the outdoor fan 14, and condenses. In addition, since the on-off valve V4 is closed and the check valve V6 is provided, the refrigerant can not flow into the second superheating circuit 30.
The normal temperature / high pressure refrigerant (liquid) generated by condensation in the outdoor heat exchanger 13 is decompressed by the expansion valve 15 in the process of flowing from the outdoor heat exchanger 13 to the refrigerant pipe L3, and a low temperature low pressure gas-liquid two-phase state And flows toward the indoor heat exchanger 16.
The refrigerant flowing into the indoor heat exchanger 16 absorbs heat from the indoor air and evaporates. The indoor air passing through the indoor heat exchanger 16 by the operation of the indoor fan 17 is cooled and supplied to the room.
The refrigerant (gas) evaporated in the indoor heat exchanger 16 to a low temperature and low pressure passes through the refrigerant piping L4, the four-way valve 18 and the refrigerant piping L9 in this order and then is sucked into the compressor 10, and the compressor 10 After being discharged, the refrigerant is discharged to the refrigerant pipe L1. At this time, since the on-off valve V2 is closed and the check valve V5 is provided, the refrigerant can not flow into the first heating circuit 20.
The refrigeration system 1 achieves room cooling while the above cycle is repeated.
Here, although the refrigerant evaporated at the indoor heat exchanger 16 to a low temperature and a low pressure is ideally a gas, the liquid phase may be mixed. In that case, the overheat operation described below is performed. This is the same even during heating operation.

[Overheat operation: Fig. 2 (b)]
Next, the overheat operation will be described with reference to FIG.
The basic high-temperature and high-pressure refrigerant is discharged from the compressor 10 also during the superheating operation, and after passing through the outdoor heat exchanger 13, the expansion valve 15, and the indoor heat exchanger 16, the refrigerant is sucked into the compressor 10 Since the flow does not change, the following description will focus on the differences from normal operation.

First, the open (ON) and closed (OFF) states of the on-off valves V1 to V4 of the first heating circuit 20 and the second heating circuit 30 are as follows.
V1: closed (OFF) V2: open (ON) V3: open (ON) V4: closed (OFF)

  The low-temperature low-pressure refrigerant (gas) that has passed through the indoor heat exchanger 16 flows into the refrigerant pipe L5 before the on-off valve V1 because the on-off valve V1 is closed and the on-off valve V2 is open. After passing through the heat exchanger 21, it flows through the refrigerant pipe L6. Since the check valve V5 provided in the refrigerant pipe L6 faces in the forward direction with respect to the flow of the refrigerant, it passes through the check valve V5 and then flows into the refrigerant pipe L4, and the following is the same as the normal operation Is drawn into the compressor 10.

  The refrigerant flowing through the first heating circuit 20 in the above order is overheated by heat exchange with the high-temperature high-pressure refrigerant flowing through the indoor heat exchanger 16 when passing through the first superheating heat exchanger 21, The refrigerant is returned to the refrigerant pipe L4 through the refrigerant pipe L6. As described above, the refrigerant drawn into the compressor 10 after passing through the first heating circuit 20 is overheated in the first superheating heat exchanger 21.

[Heating operation]
Also in the heating operation, the normal operation in which the refrigerant is not drawn into the circulation circuit of the second heating circuit 30 (FIG. 3A) and the heating operation in which the refrigerant is drawn into the circulation circuit of the first heating circuit 20 (FIG. 3B) Because there are, and will be described below in this order. Similarly to the cooling operation even heating operation, based on the comparison result of the temperature T and the threshold temperature T _R of the refrigerant controller 50 is detected by the temperature sensor S, switching to superheat operation from normal operation, usually from overheating operation You can switch to driving.

[Normal operation: Fig. 3 (a)]
During the heating operation, the refrigeration apparatus 1 has the first port P1 and the fourth port P4 of the four-way valve 18 connected together, and the second port P2 and the third port P3 connected together. That is, in the heating operation, the refrigerant pipe L1 and the refrigerant pipe L4 are connected, and the refrigerant pipe L3 and the refrigerant pipe L9 are connected.
Further, the states of opening (ON) and closing (OFF) of the on-off valves V1 to V4 of the first overheat circuit 20 and the second overheat circuit 30 are as follows, which are the same as the cooling operation.
V1: Open (ON) V2: Closed (OFF) V3: Open (ON) V4: Closed (OFF)

Now, when the compressor 10 is operated, the high temperature / high pressure refrigerant (gas) compressed by the compressor 10 is discharged to the refrigerant pipe L1, and flows through the refrigerant pipe L4 through the four-way valve 18. Since the open / close valve V1 is open, the high-temperature and high-pressure refrigerant flows into the indoor heat exchanger 16, exchanges heat with the indoor air blown by the indoor fan 17, and is condensed and liquefied by radiating heat to the indoor side. . Further, since the on-off valve V2 is closed and the check valve V5 is provided, the refrigerant can not flow into the first heating circuit 20.
The normal temperature / high pressure refrigerant (liquid) generated by condensation in the indoor heat exchanger 16 is decompressed by the expansion valve 15 in the process of flowing from the indoor heat exchanger 16 to the refrigerant pipe L3, and a low temperature low pressure gas-liquid two-phase state And flows toward the outdoor heat exchanger 13.
The refrigerant flowing into the outdoor heat exchanger 13 absorbs heat from the outdoor air and evaporates.
The refrigerant (gas) evaporated in the outdoor heat exchanger 13 to a low temperature and a low pressure passes through the refrigerant piping L2, the four-way valve 18 and the refrigerant piping L9 in this order and then is sucked into the compressor 10 After being discharged, the refrigerant is discharged to the refrigerant pipe L1. At this time, since the on-off valve V4 is closed and the check valve V6 is provided, the refrigerant can not flow into the second superheating circuit 30.
The refrigeration system 1 achieves room heating while the above cycle is repeated.

[Overheat operation: Fig. 3 (b)]
Next, the overheat operation will be described with reference to FIG.
The basic high-temperature and high-pressure refrigerant is discharged from the compressor 10 also during the superheating operation, and after passing through the indoor heat exchanger 16, the expansion valve 15, and the outdoor heat exchanger 13, it is sucked into the compressor 10 Since the flow does not change, the following description will focus on the differences from normal operation.

First, the open (ON) and closed (OFF) states of the on-off valves V1 to V4 of the first heating circuit 20 and the second heating circuit 30 are as follows.
V1: Open (ON) V2: Closed (OFF) V3: Closed (OFF) V4: Open (ON)

  The low-temperature low-pressure refrigerant (gas) that has passed through the outdoor heat exchanger 13 flows into the refrigerant pipe L7 in front of the on-off valve V2 because the on-off valve V2 is closed and the on-off valve V4 is open. After passing through the heat exchanger 31, it flows through the refrigerant pipe L7. Since the check valve V6 provided in the refrigerant pipe L7 is directed in the forward direction with respect to the flow of the refrigerant, it passes through the check valve V6 and then flows into the refrigerant pipe L2, and the following is the same as the normal operation Is drawn into the compressor 10.

  The refrigerant flowing through the second superheating circuit 30 in the above order is overheated by heat exchange with the high temperature / high pressure refrigerant flowing through the indoor heat exchanger 16 when passing through the second superheating heat exchanger 31, The refrigerant is returned to the refrigerant pipe L2 from the refrigerant pipe L8. As described above, the refrigerant drawn into the compressor 10 after passing through the second superheating circuit 30 is superheated in the second superheating heat exchanger 21.

[Effect of the refrigeration system 1]
As described above, the refrigerating apparatus 1 includes the first heating circuit 20 and the second heating circuit 30, and after the refrigerant is overheated using the first heating circuit 20 during the cooling operation, the second heating during the heating operation. After the refrigerant is overheated using the circuit 30, it is sucked into the compressor 10. Therefore, even if the HFO refrigerant whose high-pressure gas temperature tends to be low is used, the refrigerant sucked into the compressor 10 is prevented from becoming wet, and the reliability of the compressor 10 due to liquid compression is prevented from being impaired. can do.

The refrigeration apparatus 1 exchanges heat with the heat radiated from the outdoor heat exchanger 13 through which the high-temperature refrigerant flows, in the first superheating circuit 20 applied during the cooling operation. Therefore, since the temperature difference between the refrigerant flowing through the first superheating circuit 20 (the refrigerant to be heated) and the refrigerant flowing through the outdoor heat exchanger 13 can be increased, the degree of overheating of the refrigerant to be heated can be increased. In addition, since the refrigerant is not overheated using the indoor heat exchanger 16 during the cooling operation, there is no possibility that the performance of the indoor heat exchanger 16 is degraded. The same applies to the second heating circuit 30 applied during heating operation.
On the other hand, since the superheating mechanism of Patent Document 1 exchanges heat between the refrigerant liquefied by passing through the outdoor heat exchanger 13 at the time of cooling operation and the refrigerant to be heated, the temperature difference between the two is small. The degree of overheating of the refrigerant to be heated is smaller than that of the present embodiment.

  The refrigeration apparatus 1 can selectively operate cooling and heating by flowing the refrigerant in the reverse direction using the four-way valve 18, but the first heating circuit 20 corresponding to the cooling operation and the second corresponding to the heating operation An overheat circuit 30 is provided. Therefore, the compressor 10 can avoid the liquid compression which is likely to occur when the HFO refrigerant is used in either the cooling operation or the heating operation.

  In addition, the refrigeration apparatus 1 can switch between the normal operation and the overheat operation based on the detection result of the discharge temperature of the refrigerant by the temperature sensor S. Therefore, there is an advantage that operation control can be performed according to the heat load while always performing the overheat operation. In other words, if the heat load is high due to the constant overheat operation, the overheat operation may be excessive, and in the worst case, the motor oil which is the drive source of the compressor 10 may overheat. On the other hand, the above problems can be prevented by switching the operation according to the heat load.

Second Embodiment
Next, a refrigerating apparatus 2 according to a second embodiment of the present invention will be described with reference to FIGS.
The refrigeration system 2 is a system dedicated to cooling, and the basic configuration is the same as that of the refrigeration system 1 except that the four-way valve 18 for switching between the cooling operation and the heating operation is not provided. Therefore, while attaching | subjecting the code | symbol same as the freezing apparatus 1 to the component similar to the freezing apparatus 1, below, it demonstrates centering around difference with the freezing apparatus 1. FIG.

[Constitution]
The configuration of the main circuit in the refrigeration system 2 will be described with reference to FIG.
In the compressor 10, one end of a refrigerant pipe L2 is connected to the discharge side of the refrigerant, and the other end of the refrigerant pipe L2 is connected to the outdoor heat exchanger 13.
One end of a refrigerant pipe L3 is connected to the outdoor heat exchanger 13. The other end of the refrigerant pipe L3 is connected to the indoor heat exchanger 16. The refrigerant pipe L3 is provided with an expansion valve 15, and adiabatically expands the refrigerant passing through the refrigerant pipe L3.
One end of a refrigerant pipe L4 is connected to the indoor heat exchanger 16, and the other end of the refrigerant pipe L4 is connected to the suction side of the compressor 10.

In the refrigeration system 2 having the above circuit configuration, the high temperature / high pressure refrigerant (gas) discharged from the compressor 10 during the cooling operation is the refrigerant pipe L1, the outdoor heat exchanger 13, the refrigerant pipe L3, the indoor heat exchange The refrigerant passes through the heater 16 and the refrigerant pipe L4 in this order, and is drawn into the compressor 10. However, when the third heating circuit 40 described below operates, part of the flow of the refrigerant is changed.
In addition, since the refrigeration system 2 is dedicated to cooling, the refrigerant circulation circuit corresponding to the second heating circuit 30 included in the refrigeration system 1 is not provided.

  The third overheat circuit 40 includes a third overheat heat exchanger 41, a refrigerant pipe L15 having one end connected to the third overheat heat exchanger 41, and the other end connected to the refrigerant pipe L4, and one end connected to the third overheat heat exchanger 41. And a refrigerant pipe L16, the other end of which is connected to the refrigerant pipe L4, and the refrigerant pipe L4, the refrigerant pipe L15, the third overheat heat exchanger 41, and the refrigerant pipe L16 form a refrigerant circulation circuit.

  The third overheat heat exchanger 41 is a member that functions in the same manner as the first overheat heat exchanger 21. The third overheat heat exchanger 41 is provided in proximity to the outdoor heat exchanger 13 and flows through the outdoor heat exchanger 13 in the process of passing the refrigerant. Heat exchange with the refrigerant superheats the refrigerant drawn into the compressor 10.

The third superheat circuit 40 is on the refrigerant pipe L4, and is provided between the connection part of the refrigerant pipe L15 and the refrigerant pipe L4, and between the connection part of the refrigerant pipe L16 and the refrigerant pipe L4, and the refrigerant pipe L5. An on-off valve V12 is provided on the top. The third heating circuit 40 also includes a check valve V15 on the refrigerant pipe L16. The check valve V15 allows the flow of the refrigerant from the third overheat heat exchanger 41 to the refrigerant pipe L4, but the reverse, that is, the flow of the refrigerant from the refrigerant pipe L4 to the third overheat heat exchanger 41 Stop it.
The third overheat circuit 40 draws the refrigerant into the circulation circuit by controlling the opening and closing of the on-off valve V11 and the on-off valve V12, and does not draw the refrigerant into the circulation circuit. Either of the normal operation is selectively performed.
The connection position of the refrigerant pipe L15 and the refrigerant pipe L16 to the refrigerant pipe L4 shown in FIG. 5 is an example, and the refrigerant pipe L15 and the refrigerant pipe L16 are connected to the refrigerant pipe L4 at a position close to the compressor 10. Can.

The third overheat heat exchanger 41 is disposed close to the outdoor heat exchanger 13 so as to be able to exchange heat with the outdoor heat exchanger 13. Specifically, as shown in FIG. 7 (a), based on the direction A of the outdoor air blown by the outdoor fan 14 as shown in FIG. 7 (b) or downstream of the outdoor heat exchanger 13. The third superheated heat exchanger 41 can be disposed upstream of the outdoor heat exchanger 13. The refrigerant passing through the third superheated heat exchanger 41 can be heated either at the downstream side or the upstream side.
As shown in FIG. 7, the third superheated heat exchanger 41 has only a form in which a refrigerant pipe made of copper, for example, is made to meander, and is not provided with a cooling fin. The heat exchanger functions as a heat exchanger to obtain the heat necessary for cooling from the outdoor heat exchanger 13. That is, in the present invention, a member capable of exchanging heat as a function can be widely used as a heat exchanger. In addition, since the 3rd overheat heat exchanger 41 is not equipped with a cooling fin, it contributes to cost reduction. On the other hand, the first overheat heat exchanger 21 and the second overheat heat exchanger 31 having the cooling fins can make the heat exchange amount larger than that of the third overheat heat exchanger 41.

[Operation of refrigeration system 2]
Next, the operation of the refrigeration system 2 will be described with reference to FIG.
The refrigeration apparatus 2 can overheat the refrigerant by operating the third heating circuit 40 while performing the cooling operation.

Also in the cooling operation of the refrigeration system 2, a normal operation (FIG. 6 (a)) in which the refrigerant is not drawn into the circulation circuit, and an overheat operation (FIG. 6 (b)) drawing the refrigerant in the circulation circuit of the third heating circuit 40 Because there are, I will be described in this order below. As in the first embodiment, based on the comparison result of the temperature T and the threshold temperature T _R of the refrigerant controller 50 is detected by the temperature sensor S, switching to superheat operation from normal operation, the normal operation from overheating operation Switch between

[Normal operation: Fig. 6 (a)]
The refrigeration apparatus 2 performs the opening (ON) and closing (OFF) of the on-off valves V11 and V12 during normal operation as follows.
V11: Open (ON) V12: Closed (OFF)

Now, when the compressor 10 is operated, the high-temperature, high-pressure (gas) refrigerant compressed by the compressor 10 is discharged to the refrigerant pipe L2, flows into the outdoor heat exchanger 13, and is blown by the outdoor fan 14. It releases heat to outdoor air and condenses.
The normal temperature / high pressure refrigerant (liquid) generated by condensation in the outdoor heat exchanger 13 is decompressed by the expansion valve 15 in the process of flowing from the outdoor heat exchanger 13 to the refrigerant pipe L3, and a low temperature low pressure gas-liquid two-phase state And flows toward the indoor heat exchanger 16.
The refrigerant flowing into the indoor heat exchanger 16 absorbs heat from the indoor air and evaporates. The indoor air passing through the indoor heat exchanger 16 by the operation of the indoor fan 17 is cooled and supplied to the room.
The refrigerant (gas) evaporated in the indoor heat exchanger 16 to a low temperature and a low pressure passes through the refrigerant pipe L4 and is then sucked into the compressor 10, and after being brought to a high temperature and high pressure by the compressor 10, discharged to the refrigerant pipe L2. Be done. At this time, since the on-off valve V12 is closed and the check valve V15 is provided, the refrigerant can not flow into the third heating circuit 40.
The refrigeration system 2 achieves room cooling while the above cycle is repeated.

[Overheat operation: Fig. 6 (b)]
Next, the overheat operation will be described with reference to FIG.
The basic high-temperature and high-pressure refrigerant is discharged from the compressor 10 also during the superheating operation, and after passing through the outdoor heat exchanger 13, the expansion valve 15, and the indoor heat exchanger 16, the refrigerant is sucked into the compressor 10 Since the flow does not change, the following description will focus on the differences from normal operation.

First, the open (ON) and closed (OFF) states of the on-off valves V11 and V12 of the third heating circuit 40 are as follows.
V11: Open (ON) V12: Closed (OFF)

  The low-temperature low-pressure refrigerant (gas) that has passed through the indoor heat exchanger 16 flows into the refrigerant pipe L15 before the on-off valve V11 because the on-off valve V11 is closed and the on-off valve V12 is open, and the third overheated After passing through the heat exchanger 41, it flows through the refrigerant pipe L16. Since the check valve V15 provided in the refrigerant pipe L16 faces in the forward direction with respect to the flow of the refrigerant, it passes through the check valve V15, flows into the refrigerant pipe L4, and is drawn into the compressor 10.

  The refrigerant flowing through the third heating circuit 40 in the above order is overheated by heat exchange with the high-temperature high-pressure refrigerant flowing through the indoor heat exchanger 16 when passing through the third superheating heat exchanger 41, It returns to the refrigerant pipe L4 through the refrigerant pipe L16. As described above, the refrigerant drawn into the compressor 10 after passing through the third heating circuit 40 is overheated in the third superheating heat exchanger 41.

[Effect of the refrigeration system 2]
As described above, the refrigeration system 2 includes the third heating circuit 40, and after the refrigerant is heated using the third heating circuit 40 during the cooling operation, the refrigerant 10 is sucked into the compressor 10. Therefore, even if the HFO refrigerant whose high-pressure gas temperature tends to be low is used, the refrigerant sucked into the compressor 10 is prevented from becoming wet, and the reliability of the compressor 10 due to liquid compression is prevented from being impaired. can do.

  The refrigeration system 2 causes the third heating circuit 40 to exchange heat with the heat radiated from the outdoor heat exchanger 13 through which the high-temperature refrigerant flows. Therefore, the degree of overheating of the refrigerant to be overheated can be increased as in the case of the refrigeration system 1, and there is no risk of degrading the performance of the indoor heat exchanger 16.

As mentioned above, although the present invention was explained based on a desirable embodiment, unless it deviates from the main point of the present invention, it is possible to sort out the composition quoted by the above-mentioned embodiment, or to change suitably to other composition. It is.
Although the said embodiment used temperature sensor S attached to refrigerant | coolant piping L1 to detect the state of a refrigerant | coolant, this invention is not limited to this. The object to be detected is not limited to temperature, and for example, the state of the refrigerant can be known by detecting the pressure of the refrigerant, and the position of detection can be detected not only on the discharge side of the compressor 10 but also on the suction side. .

1, 2 refrigeration apparatus 10 compressor 13 outdoor heat exchanger 14 outdoor fan 15 expansion valve 16 indoor heat exchanger 17 indoor fan 18 four-way valve 20 first overheat circuit 21 first overheat heat exchanger 30 second overheat circuit 31 second overheat circuit Overheat heat exchanger 40 Third overheat circuit 41 Third overheat heat exchangers L1 to L9, L15, L16 Refrigerant piping P1 first port P2 second port P3 third port P4 fourth port S temperature sensors V1 to V4, V11, V12 on-off valve V5, V6, V15 check valve

Claims (4)

A compressor for compressing a refrigerant, a condenser for radiating and condensing the refrigerant compressed by the compressor, an expansion mechanism for decompressing the refrigerant condensed in the condenser, and a pressure reduced in the expansion mechanism A main circuit which is connected to an evaporator for evaporating the refrigerant and which constitutes a circulation circuit of the refrigerant;
Between the evaporator and the compressor, it is provided in parallel with the main circuit, and the refrigerant evaporated in the evaporator is subjected to heat exchange with the refrigerant flowing through the condenser and then returned to the main circuit Circuit,
An outdoor heat exchanger that functions as the condenser during cooling operation and functions as the evaporator during heating operation;
An indoor heat exchanger that functions as the evaporator during the cooling operation and functions as the condenser during the heating operation;
The heating circuit is
A first superheating circuit which collects heat from the outdoor heat exchanger functioning as the condenser during the cooling operation;
A second superheating circuit collecting heat from the indoor heat exchanger functioning as the condenser during the heating operation;
A refrigeration apparatus comprising: Normal operation in which the refrigerant evaporated by the evaporator is drawn into the compressor via the main circuit;
The system further includes an operation switching mechanism that selectively performs an overheat operation in which the refrigerant evaporated by the evaporator is returned to the main circuit via the overheat circuit and then sucked into the compressor.
The refrigeration apparatus according to claim 1. The operation switching mechanism is
The normal operation and the superheating operation are switched according to the state of one or both of the refrigerant sucked into the compressor and the refrigerant discharged from the compressor.
The refrigeration apparatus according to claim 2. The superheating circuit includes a heat exchanger which is disposed downstream of the air flow to the condenser, receives heat radiated from the refrigerant via the air flow, and superheats the refrigerant returned to the main circuit.
The freezing apparatus as described in any one of Claims 1-3.

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