WO2020079835A1

WO2020079835A1 - Air conditioner

Info

Publication number: WO2020079835A1
Application number: PCT/JP2018/039035
Authority: WO
Inventors: 幹佐藤; 拓未西山; 伊東　大輔
Original assignee: 三菱電機株式会社
Priority date: 2018-10-19
Filing date: 2018-10-19
Publication date: 2020-04-23
Also published as: JPWO2020079835A1; EP3869114A1; EP3869114B1; JP7034325B2; EP3869114A4

Abstract

An air conditioner (100) comprises: a main circuit (30); a first bypass channel (B1) by which a second heat exchanger (7) pipe on the side of a first expansion valve (6a) and a discharge side pipe of a compressor (1) communicate; a second bypass channel (B2) by which an intake side pipe of the compressor (1) and the discharge side pipe of the compressor (1) communicate; and a first channel selection device (20) that is configured to allow refrigerant discharged by the compressor (1) to flow in at least one of a first heat exchanger (5), the first bypass channel (B1), and the second bypass channel (B2), selectively. During heating operations, the first channel selection device (20) selects at least the first heat exchanger (5). During defrost operations, the first channel selection device (20) selects at least the second bypass channel (B2) and then selects at least the first bypass channel (B1). Due to this configuration, an air conditioner can be provided that is capable of defrosting in a short time.

Description

Air conditioner

The present invention relates to an air conditioner.

Conventionally, a refrigeration cycle apparatus including a bypass circuit connecting a compressor discharge side and an outdoor heat exchanger inlet side is known (Patent Document 1: JP2009-145032A). When the outdoor heat exchanger is frosted, this refrigeration cycle device can quickly defrost by causing the refrigerant discharged from the compressor to flow to the outdoor heat exchanger through the bypass circuit.

JP-A-2009-145032

In the refrigeration cycle apparatus described in JP 2009-145032 A, the defrosting time is shortened by causing the refrigerant to flow through the outdoor heat exchanger through the bypass flow path connecting the compressor discharge side and the outdoor heat exchanger inlet side. You can However, when a refrigerant having a low discharge temperature (for example, R290, which is one of HC (hydrocarbon) refrigerants) is enclosed in the refrigerant circuit, the temperature difference between the refrigerant and the outdoor heat exchanger becomes small and per unit time. There is a problem that the time required for defrosting cannot be shortened because the amount of heat exchange of is reduced.

The present invention has been made to solve the above problems, and an object thereof is to provide an air conditioner capable of defrosting in a short time regardless of the refrigerant used.

In the air conditioner according to the present disclosure, during heating operation, the refrigerant circulates in the order of the compressor, the first heat exchanger, the first expansion valve, and the second heat exchanger, and the second circuit of the second heat exchanger. The first bypass flow passage that connects the first expansion valve side pipe and the discharge side pipe of the compressor, the second bypass flow passage that connects the suction side pipe of the compressor and the discharge side pipe of the compressor, and the compressor are A first flow path selection device configured to selectively pass the discharged refrigerant through at least one of the first heat exchanger, the first bypass flow path, and the second bypass flow path. During the heating operation, the first flow path selection device selects at least the first heat exchanger. During the defrosting operation, the first flow path selection device selects at least the first bypass flow path after selecting at least the second bypass flow path.

According to the present invention, the defrosting time is shortened because the refrigerant is introduced into the heat exchanger that has been frosted by the bypass flow path after the temperature of the refrigerant is raised compared to that during normal heating.

1 is a schematic configuration diagram showing a configuration of an air conditioner 100 according to Embodiment 1. 7 is a flowchart for explaining the operation of each element during defrosting operation in the first embodiment. It is a figure which shows the state of the element in each process of the flowchart of FIG. It is a figure which shows the flow of the refrigerant at the time of heating (S100, S101, S106) of Embodiment 1. It is a figure which shows the flow of the refrigerant in the defrosting 1st step (S102, S103) of Embodiment 1. It is a figure which shows the flow of the refrigerant | coolant in the defrosting 2nd step (S104, S105) of Embodiment 1. It is a ph diagram which shows the state of the refrigerant of the comparative example which performs the general defrosting which reverses the flow of the refrigerant to the cooling operation direction. FIG. 4 is a ph diagram showing the state of the refrigerant during the defrosting operation in the first embodiment. It is the figure which overlapped and showed the temperature distribution of the refrigerant | coolant in the defrosting operation of the comparative example in the 2nd heat exchanger 7, and the defrosting operation of Embodiment 1. FIG. 7 is a diagram showing a difference in time from a frosting determination to the start of a defrosting operation in each of the comparative example and the first embodiment. FIG. 7 is a diagram showing a difference in time from the end of defrosting to the return to heating in each of the comparative example and the first embodiment. It is a schematic block diagram which shows the structure of the air conditioning apparatus 200 which concerns on Embodiment 2. 9 is a flowchart for explaining the operation of each element during a defrosting operation in the second embodiment. It is a figure which shows the state of the element in each process of the flowchart of FIG. It is a figure which shows the flow of the refrigerant at the time of heating (S200, S201, S208) of Embodiment 2. It is a figure which shows the flow of the refrigerant in the defrosting 1st step (S202, S203) of Embodiment 2. It is a figure which shows the flow of the refrigerant | coolant in the defrosting 2nd step (S204, S205) of Embodiment 2. It is a figure which shows the flow of the refrigerant in the defrosting 3rd step (S206, S207) of Embodiment 2. In Embodiment 2, it is a ph diagram showing the state of the refrigerant at the time when the refrigerant starts to be distributed to the second bypass flow passage B2 just before the end of defrosting. FIG. 9 is a ph diagram showing a state of the refrigerant at a point in time when a certain time has elapsed after the refrigerant was started to be distributed to the second bypass flow passage B2 in the second embodiment. It is a figure which shows the time change of the discharge temperature of the refrigerant from the defrosting start of a comparative example which performs defrosting by cooling operation to heating return. FIG. 9 is a diagram showing a temporal change in discharge temperature of the refrigerant from the start of defrosting to the return to heating in the second embodiment. It is a schematic block diagram which shows the structure of the air conditioning apparatus 300 which concerns on Embodiment 3. 11 is a flowchart for explaining the operation of each element during defrosting operation of the first heat exchange unit 7a in the third embodiment. It is a figure which shows the state of the element in each process of the flowchart of FIG. It is a figure which shows the flow of the refrigerant at the time of heating (S300, S301, S306) of Embodiment 3. It is a figure which shows the flow of the refrigerant in the 1st stage (S302, S303) at the time of the defrosting operation of the 1st heat exchange part 7a. It is a figure which shows the flow of the refrigerant in the 2nd step (S304, S305) at the time of the defrosting operation of the 1st heat exchange part 7a. 11 is a flowchart for explaining the operation of each element during the defrosting operation of the second heat exchange section 7b in the third embodiment. FIG. 30 is a diagram showing states of elements in each process of the flowchart of FIG. 29. It is a figure which shows the flow of the refrigerant in the 1st stage (S302A, S303A) at the time of the defrosting operation of the 2nd heat exchange part 7b. It is a figure which shows the flow of the refrigerant | coolant in the 2nd stage (S304A, S305A) at the time of the defrosting operation of the 2nd heat exchange part 7b. 13 is a flowchart for explaining an example of a process of performing defrosting by prioritizing the first heat exchange section 7a over the second heat exchange section 7b in the third embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, a plurality of embodiments will be described, but it is planned from the beginning of the application to appropriately combine the configurations described in the embodiments. In the drawings, the same or corresponding parts will be denoted by the same reference characters and description thereof will not be repeated.

Embodiment 1.
FIG. 1 is a schematic configuration diagram showing a configuration of an air conditioner 100 according to the first embodiment.

Referring to FIG. 1, the air conditioner 100 includes a main circuit 30, a first bypass flow passage B1, a second bypass flow passage B2, and a first flow passage selecting device 20.

The air conditioner 100 further includes a compressor 1, a four-way valve 4, an extension pipe 9a, a first heat exchanger 5, an extension pipe 9b, a first expansion valve 6a, and a second heat exchanger 7. Prepare Usually, the first heat exchanger 5 is an indoor heat exchanger arranged indoors, and the second heat exchanger 7 is an outdoor heat exchanger arranged outdoors.

During the heating operation, the refrigerant in the main circuit 30 is the compressor 1, the four-way valve 4, the extension pipe 9a, the first heat exchanger 5, the extension pipe 9b, the first expansion valve 6a, the second heat exchanger 7, the four-way valve. It circulates in the order of 4 and returns to the compressor 1.

The first bypass flow path B1 connects the point P2 of the first expansion valve 6a side pipe of the second heat exchanger 7 and the discharge side pipe P1 of the compressor 1 to each other.

The second bypass flow path B2 connects the point P3 of the suction side pipe of the compressor 1 and the point P1 of the discharge side pipe of the compressor 1.

The first flow path selection device 20 is configured to selectively pass the refrigerant discharged from the compressor 1 through at least one of the first heat exchanger 5, the first bypass flow path B1, and the second bypass flow path B2. To be done. In the first embodiment, the first flow path selection device 20 selectively selects the refrigerant discharged from the compressor 1 into one of the first heat exchanger 5, the first bypass flow path B1, and the second bypass flow path B2. Configured to pass through.

The air conditioner 100 further includes a second expansion valve 6b. The second expansion valve 6b is arranged between the second bypass passage B2 and the suction side pipe of the compressor 1 in FIG. The second expansion valve 6b may be provided in the middle of the second bypass flow passage B2.

The first flow path selecting device 20 shown in FIG. 1 includes a solenoid valve 3a provided in a pipe C0 between a point P1 of the discharge side pipe of the compressor 1 and the first heat exchanger 5, and a first bypass flow passage B1. And an electromagnetic valve 3b provided in a branch pipe B0 from the main circuit 30 shared by the second bypass flow passage B2 and the branch pipe B0 connected to either one of the first bypass flow passage B1 and the second bypass flow passage B2. And a flow path switching valve 8 for switching.

The branch pipe B0 and the bypass flow passage B1 connect the point P1 between the discharge side of the compressor 1 and the solenoid valve 3a and the point P2 between the first expansion valve 6a and the inlet side of the second heat exchanger 7. It Further, the branch pipe B0 and the bypass flow passage B2 connect the point P3 and the point P1 between the four-way valve 4 and the second expansion valve 6b.

A fan (not shown) for blowing air is provided on the air outlet side or the air inlet side of each of the first heat exchanger 5 and the second heat exchanger 7. As each fan, a line flow fan, a propeller fan, a turbo fan, a sirocco fan, or the like can be used. Also, a plurality of fans may be provided for one heat exchanger. Further, the configuration shown in FIG. 1 is the minimum component capable of cooling and heating operation, and devices such as a gas-liquid separator, a receiver and an accumulator may be added to the main circuit 30.

The air conditioner 100 further includes a control device 50 and

temperature sensors

2a and 2b. The temperature sensor 2a detects the temperature of the refrigerant discharged from the compressor 1. The temperature sensor 2b detects the surface temperature of the second heat exchanger 7 at a position close to the point P2d side which is the refrigerant outlet of the second heat exchanger 7 during the heating operation. The control device 50 is based on the temperature detected by the

temperature sensors

2a and 2b and a command from the user, and the compressor 1, the four-way valve 4, the first expansion valve 6a, the flow path selection device 20, the second expansion valve 6b and not shown. Control the fan.

The control device 50 includes a processor 51, a memory 52, and an input / output interface 53. The memory 52 includes, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and a flash memory. The flash memory stores an operating system, application programs, and various data.

The control device 50 shown in FIG. 1 is realized by the processor 51 executing the operating system and application programs stored in the memory 52. When executing the application program, various data stored in the memory 52 is referred to.

In addition, in the first embodiment, the type of the refrigerant enclosed in the air conditioner is not particularly limited. For example, an HFC (hydrofluorocarbon) refrigerant, an HFO (hydrofluoroolefin) refrigerant, an HC (hydrocarbon) refrigerant, or a non-azeotropic mixed refrigerant may be enclosed.

The air conditioner 100 configured as shown in FIG. 1 may frost on the second heat exchanger 7 arranged outdoors during the heating operation. A defrosting operation is executed to melt the frost. In the heating operation and the defrosting operation, the flow of the refrigerant is changed by the first flow path selection device 20.

During the heating operation, the first flow path selection device 20 selects at least the first heat exchanger 5. As a result, the high-temperature and high-pressure refrigerant discharged from the compressor 1 is radiated by the first heat exchanger 5 and condensed.

During the defrosting operation, the first flow path selection device 20 selects at least the first bypass flow path B1 after selecting at least the second bypass flow path B2. As a result, the refrigerant whose temperature has risen through the second bypass flow passage B2 then flows into the second heat exchanger 7 from the first bypass flow passage B1 and defrosting is performed.

Next, the operation of the air conditioner 100 according to the first embodiment having the above configuration will be described. FIG. 2 is a flowchart for explaining the operation of each element during the defrosting operation in the first embodiment. FIG. 3 is a diagram showing states of elements in each processing of the flowchart of FIG.

When the heating operation is started, the control device 50 causes the solenoid valve 3a to be opened and the solenoid valve 3b to be closed in step S100 so that the passage switching valve 8 selects the second bypass passage B2. Control the valve.

FIG. 4 is a diagram showing a refrigerant flow during heating (S100, S101, S106) according to the first embodiment. As shown in FIG. 4, the refrigerant is discharged from the compressor 1, and the four-way valve 4, the first heat exchanger 5, the first expansion valve 6a, the second heat exchanger 7, the four-way valve 4, the second expansion valve It circulates in the order of 6b and returns to the compressor 1.

Referring again to FIGS. 2 and 3, in step S101, the control device 50 acquires information for determining whether or not the second heat exchanger 7 is frosted, and then the second heat exchanger. It is determined whether or not No. 7 is frosted. Specifically, the control device 50 obtains the detection result of the temperature sensor 2b, and based on the detection result, the surface temperature of the second heat exchanger 7 is a predetermined first threshold value (for example, − 3 ° C.) or less is determined. The controller 50 determines that the second heat exchanger 7 is frosted when the surface temperature of the second heat exchanger 7 is equal to or lower than the first threshold value.

If it is determined in step S101 that no frost has formed (NO in S101), the process is temporarily returned to the main routine, and the processes of S100 and S101 are repeated again. When it is determined in step S101 that frost has formed (YES in S101), the process proceeds to step S102.

In step S102, the control device 50 closes the solenoid valve 3a and opens the solenoid valve 3b. The selection of the flow path switching valve 8 is maintained as the second bypass flow path B2.

FIG. 5 is a diagram showing the flow of the refrigerant in the first defrosting stage (S102, S103) according to the first embodiment. As shown in FIG. 5, in step S102, the refrigerant discharged from the compressor 1 passes through the second bypass passage B2, is decompressed by the second expansion valve 6b, and is again sucked into the compressor 1. Since the solenoid valve 3a is in the closed state, a part of the refrigerant staying in the first heat exchanger 5 and the second heat exchanger 7 is sucked out through the path indicated by the broken line arrow and is indicated by the solid line arrow. The temperature is raised in a loop.

The controller 50 fully opens the expansion valve 6a in step S102. This is because when the defrosting operation is switched, the refrigerant remaining in the main circuit is swiftly passed through the loop indicated by the solid arrow including the second bypass flow passage B2. Further, the control device 50 sets the opening degree of the second expansion valve 6b to the same opening degree as that of the first expansion valve 6a during the heating operation before starting the defrosting operation. This is to prevent a state where the pressure difference before and after the second expansion valve 6b becomes small and the discharge pressure and discharge temperature of the refrigerant do not rise when the opening degree of the second expansion valve 6b is too large. Moreover, when the opening degree of the second expansion valve 6b is too small, the amount of the refrigerant flowing into the suction side of the compressor 1 is prevented from becoming excessively small.

Referring again to FIGS. 2 and 3, in step S103, control device 50 obtains information for determining whether the discharge temperature of the refrigerant has reached the target value, and the discharge temperature of the refrigerant is It is determined whether or not the target value has been reached. Specifically, the control device 50 acquires the detection result of the temperature sensor 2a, and based on the detection result, the temperature of the refrigerant discharged from the compressor 1 is set to a second threshold value T2 (for example, 100). ℃) has been reached.

Note that the density of the sucked refrigerant may decrease with time while the processes of steps S102 and S103 are repeated. In that case, since the mass flow rate of the refrigerant sucked into the compressor 1 decreases, the discharge temperature of the refrigerant may not easily rise with time. Therefore, in step S103, when the refrigerant discharge temperature rise at a constant time interval (for example, 5 seconds) is less than a predetermined third threshold value (for example, 10 ° C.), the operating frequency of the compressor 1 is set to It may be controlled to increase. Alternatively, when the temperature of the refrigerant discharged from the compressor 1 does not reach the predetermined second threshold value (for example, 100 ° C.) even after a certain fixed time (for example, 60 seconds) has elapsed from the start of step S102, The process may proceed to step S104.

Next, in step S104, the control device 50 switches the selection of the passage switching valve 8 from the second bypass passage B2 to the first bypass passage B1.

FIG. 6 is a diagram showing the flow of the refrigerant in the defrosting second stage (S104, S105) according to the first embodiment. As shown by the arrow in FIG. 6, in step S104, the high-temperature and high-pressure refrigerant discharged from the compressor 1 flows through the first bypass passage B1 and is introduced into the second heat exchanger 7. In this way, the second heat exchanger 7 is defrosted. Further, the refrigerant flowing out from the second heat exchanger 7 is decompressed by the second expansion valve 6b and is again sucked into the compressor 1.

Note that the operating frequency of the compressor 1 in step S104 is preferably higher than that of normal heating operation. This is different from the general defrosting operation in which the refrigerant is circulated backward in the cooling direction, and since it is the defrosting operation in the overheated gas region, the flow rate of the refrigerant is small and the amount of heat used for defrosting is small. This is to prevent

Returning to FIG. 2 again, the control device 50 determines in step S105 whether or not to finish the defrosting. Specifically, the controller 50 has a surface temperature of the second heat exchanger 7 that is equal to or higher than a predetermined third threshold value (for example, 0 ° C.) based on the detection signal output from the temperature sensor 2b. Or not. When the surface temperature of the second heat exchanger 7 is lower than the third threshold value (NO in S105), the control device 50 determines to continue the defrosting of the second heat exchanger 7, and proceeds to step S104. Return processing. On the other hand, when the surface temperature of the second heat exchanger 7 is equal to or higher than the third threshold value (YES in S105), the control device 50 determines to end the defrosting of the second heat exchanger 7. Then, the process proceeds to step S106.

In step S106, the control device 50 sets the solenoid valve 3a to the open state and the solenoid valve 3b to the closed state. At this time, the refrigerant flows as shown in FIG. 4, whereby the steady heating operation is performed.

As described above, during the defrosting operation, the first flow path selecting device 20 selects the second bypass flow path B2 and deselects the first bypass flow path B1 and the first heat exchanger 5 (see FIG. 5, S102, S103), and then the first bypass flow passage B1 is selected and the second bypass flow passage B2 and the first heat exchanger 5 are deselected (FIG. 6, S104, S105).

Next, effects obtained by the air conditioner 100 according to the first embodiment will be described.
When it is determined that the detection result of the temperature sensor 2b is less than or equal to the first threshold value set in advance and the second heat exchanger 7 is frosted, the control device 50 controls the solenoid valve 3a, the solenoid valve 3b, and the flow path. The switching valve 8 is operated to flow the entire amount of the refrigerant into the second bypass flow passage B2. Next, when the detection result of the temperature sensor 2a reaches or exceeds the preset second threshold value, the control device 50 operates the flow path switching valve 8 to move the second heat exchanger through the first bypass flow path B1. The second refrigerant heat exchanger 7 is defrosted by flowing the entire amount of the refrigerant into the second heat exchanger 7.

By causing the refrigerant to flow into the second bypass flow passage B2, the temperature of the refrigerant rises in the loop indicated by the solid arrow in FIG. 5, so the refrigerant discharge temperature can be made higher than that during normal heating operation.

Further, by increasing the discharge temperature of the refrigerant, when the flow path switching valve 8 is switched to the first bypass flow path B1, the refrigerant can be made to flow to the second heat exchanger 7 in a state where the temperature is higher than usual. .

FIG. 7 is a ph diagram showing the state of the refrigerant of a comparative example that executes general defrosting in which the flow of the refrigerant is reversed in the cooling operation direction. FIG. 8 is a ph diagram showing the state of the refrigerant during the defrosting operation in the first embodiment. Compared with the general defrosting in which the flow of the refrigerant is reversed in the cooling operation direction shown in FIG. 7, in the defrosting operation of the present embodiment shown in FIG. 8, the enthalpy is high and in the gas region in a more overheated state. It will be a defrosting operation.

FIG. 9 is a diagram in which the temperature distributions of the refrigerant in the defrosting operation of the comparative example and the defrosting operation of the first embodiment in the second heat exchanger 7 are overlapped and shown. In the defrosting operation of the first embodiment shown in Ta′-Tb ′ of FIG. 9, the temperature difference between the refrigerant and the second heat exchanger 7 is higher than that in the defrosting operation of the comparative example shown in Ta-Tb of FIG. Is increased and the amount of heat exchange per unit time is increased, so that defrosting can be performed in a short time.

Further, the effect of increasing the discharge temperature of the above-mentioned refrigerant and capable of performing defrosting in a short time is that the refrigerant species to be enclosed in the air conditioner such as HFC refrigerant, HFO refrigerant, HC refrigerant, non-azeotropic mixed refrigerant, etc. It doesn't matter. Therefore, by using a refrigerant with a low GWP (Global Warming Potential) (for example, R290 (GWP3) which is one of the HC refrigerants), it is possible to reduce the total GWP value in the refrigeration cycle.

Further, when the non-azeotropic mixed refrigerant is enclosed in the air conditioner, the refrigerant inlet side of the outdoor heat exchanger during heating tends to frost, but in the present embodiment, the second heat is passed through the first bypass passage B1. A high-pressure / high-temperature refrigerant gas can flow to the inlet side of the heat exchanger 7 during heating, and the temperature difference between the refrigerant and the second heat exchanger 7 increases on the inlet side of the second heat exchanger 7 during heating, resulting in a unit time The amount of heat exchange of is increased. Therefore, defrosting can be performed in a short time.

Further, compared with general defrosting in which the flow of the refrigerant is reversed in the cooling operation direction, defrosting in a gas region in a more overheated state increases suction SH and causes liquid back to the compressor 1. Since it becomes difficult, the reliability of the compressor 1 can be improved (FIGS. 7 and 8).

Further, compared with general defrosting in which the flow of the refrigerant is reversed in the cooling operation direction, since the refrigerant does not flow through the extension pipe 9a, the extension pipe 9b, and the indoor first heat exchanger 5 during the defrosting operation, The heat radiation loss can be reduced.

Further, since the defrosting operation can be performed without circulating the refrigerant through the first heat exchanger 5 in the room, it is possible to reduce a decrease in room temperature during the defrosting operation.

In the first embodiment, when the detection result of the temperature sensor 2b becomes equal to or lower than the preset first threshold value and the second outdoor heat exchanger 7 is determined to be frosted and the defrosting operation is started, the solenoid valve 3a is operated. Is closed to prevent the refrigerant from flowing into the main circuit 30, and at the same time, the solenoid valve 3b is opened to allow the entire amount of the refrigerant to flow into the second bypass passage B2, and then the passage switching valve 8 is switched to open the first bypass passage B1. It is selected and the entire amount of the refrigerant is flown to the second heat exchanger 7. Therefore, it is not necessary to switch the four-way valve 4 during the defrosting operation.

FIG. 10 is a diagram showing a difference in time from the frosting determination to the start of the defrosting operation in each of the comparative example and the first embodiment. In the present embodiment, it is not necessary to stop the compressor 1 between times t1 and t2 in order to create the pressure state necessary for switching the four-way valve 4. Therefore, as shown in FIG. 10, the time until the start of defrosting can be shortened by ΔT1 as compared with the comparative example.

When the detection result of the temperature sensor 2a becomes equal to or higher than the preset second threshold value and the defrosting of the outdoor second heat exchanger 7 is completed and the heating operation is restored, the solenoid valve 3b is closed and the solenoid valve 3a is turned on. It is opened to change the flow of the refrigerant from the first bypass flow passage B1 to the main circuit 30. Therefore, it is not necessary to switch the four-way valve 4 when returning to the heating operation.

FIG. 11 is a diagram showing a difference in time from the completion of defrosting to the return to heating in each of the comparative example and the first embodiment. In the present embodiment, it is not necessary to stop the compressor 1 between times t11 and t12 in order to create the pressure state necessary for switching the four-way valve 4. Therefore, as shown in FIG. 11, the time required to return to the heating operation can be shortened by ΔT2 as compared with the comparative example.

Embodiment 2.
FIG. 12 is a schematic configuration diagram showing the configuration of the air conditioner 200 according to the second embodiment.

Referring to FIG. 2, the air conditioner 200 includes a main circuit 30, a first bypass flow passage B1, a second bypass flow passage B2, and a first flow passage selection device 20A.

The air conditioner 200 further includes a compressor 1, a four-way valve 4, an extension pipe 9a, a first heat exchanger 5, an extension pipe 9b, a first expansion valve 6a, and a second heat exchanger 7. Prepare Usually, the first heat exchanger 5 is an indoor heat exchanger arranged indoors, and the second heat exchanger 7 is an outdoor heat exchanger arranged outdoors.

The first bypass flow passage B1 connects the first expansion valve 6a side pipe (point P2) of the second heat exchanger 7 and the discharge side pipe (point P1) of the compressor 1 to each other.

The second bypass flow passage B2 connects the suction side pipe (point P4) of the compressor 1 and the discharge side pipe (point P1) of the compressor 1.

The first flow path selection device 20A is configured to selectively pass the refrigerant discharged from the compressor 1 through at least one of the first heat exchanger 5, the first bypass flow path B1, and the second bypass flow path B2. To be done. In the second embodiment, the first flow path selection device 20A is configured to selectively pass the refrigerant discharged from the compressor 1 through the pipe C0 or the branch pipe B0. The first flow path selection device 20A is also configured to be able to distribute the refrigerant to the first bypass flow path B1 and the second bypass flow path B2 at an arbitrary ratio.

In the second embodiment, during the defrosting operation, the first flow passage selection device 20A selects the second bypass flow passage B2 and deselects the first bypass flow passage B1 and the first heat exchanger 5 (Fig. 16) Next, the first bypass flow passage B1 and the second bypass flow passage B2 are selected and the first heat exchanger 5 is deselected (FIG. 18).

The air conditioner 200 according to the second embodiment shown in FIG. 12 further includes a second expansion valve 6c, a third bypass flow path B3, a third expansion valve 6d, and a second flow path selection device.

The second expansion valve 6c is arranged in the middle of the second bypass flow passage B2. In the heating operation, the third bypass flow passage B3 is a flow passage that branches from the pipe C1 through which the refrigerant that has passed through the second heat exchanger 7 flows to reach the suction side of the compressor 1. The third expansion valve 6d is arranged in the middle of the third bypass flow passage B3. As the second channel selection device, the channel switching valve 8b that selectively connects the pipe C2 or the third bypass channel B3 can be used. The pipe C2 is a pipe that connects the pipe C1 to the suction side of the compressor 1 without passing through the third bypass flow passage B3.

The air conditioner 200 of the second embodiment has the same basic configuration as the air conditioner 100 of the first embodiment, but differs in the following first to fourth points. First of all, the main circuit 30 has the flow path switching valve 8b, and the expansion valve 6b is removed. Secondly, the flow path switching valve 8 for selecting the first bypass flow path B1 and the second bypass flow path B2 is replaced by the flow rate adjusting valve 10. Thirdly, the second expansion valve 6c is provided in the second bypass flow passage B2. Fourthly, the third bypass flow passage B3 having the third expansion valve 6d is provided. The flow rate adjusting valve 10 is configured to be able to freely adjust the amount of the refrigerant distributed in the first bypass flow passage B1 and the second bypass flow passage B2. The flow rate adjusting valve 10 may have any configuration, but for example, an electronic expansion valve may be provided in each of the two-way branch passages through which the refrigerant flows.

Note that, in FIG. 12, the same components as those in the first embodiment are designated by the same reference numerals. Further, similar to the first embodiment, a fan for blowing air is provided on the air outlet side or the air inlet side of each of the first heat exchanger 5 and the second heat exchanger 7 ( (Not shown). As the fan, a line flow fan, a propeller fan, a turbo fan, a sirocco fan, or the like can be used. Further, a configuration may be used in which a plurality of fans are used for one heat exchanger. Further, the configuration shown in FIG. 12 is the minimum component capable of cooling and heating operation, and devices such as a gas-liquid separator, a receiver and an accumulator may be added to the main circuit 30.

The air conditioner 200 further includes a control device 50 and

temperature sensors

2a and 2b and a command from the user, and the compressor 1, the four-way valve 4, the first expansion valve 6a, the flow path selection device 20, the second expansion valve 6b and not shown. Control the fan. Since the basic configuration of control device 50 is similar to that of the first embodiment, description thereof will not be repeated.

In addition, in the second embodiment, the type of the refrigerant enclosed in the air conditioner is not particularly limited. For example, HFC refrigerant, HFO refrigerant, HC refrigerant, or non-azeotropic mixed refrigerant may be enclosed.

Next, the operation of the air conditioner 200 according to the second embodiment having the above configuration will be described. FIG. 13 is a flowchart for explaining the operation of each element during the defrosting operation in the second embodiment. FIG. 14 is a diagram showing states of elements in each process of the flowchart of FIG.

The defrosting operation executed in the second embodiment includes the frosting determination (S201), the constant discharge temperature reaching determination (S203), and the defrosting end determination (S205) in the first embodiment. It is the same as the discharge temperature arrival determination (S103) and the defrosting end determination (S105). However, the second embodiment differs from the first embodiment in that a process involving valve operation (S200, S202, S204, S206, S207) and a defrosting constant stage progress determination (S205) are performed.

When the heating operation is started, in step S200, the control device 50 controls the solenoid valve 3a so that the solenoid valve 3a is in the open state and the solenoid valve 3b is in the closed state, and the passage switching valve 8b controls these valves so as to select the pipe C2. To do.

FIG. 15 is a diagram showing a refrigerant flow during heating (S200, S201, S208) according to the second embodiment. As shown in FIG. 15, the refrigerant is discharged from the compressor 1, and the four-way valve 4, the first heat exchanger 5, the first expansion valve 6a, the second heat exchanger 7, the four-way valve 4, the flow path switching valve. It circulates in the order of 8b and returns to the compressor 1.

Referring again to FIG. 13 and FIG. 14, in step S201, the control device 50 acquires information for determining whether the second heat exchanger 7 is frosted, and then the second heat exchanger. It is determined whether or not No. 7 is frosted. Specifically, the control device 50 acquires the detection result of the temperature sensor 2b, and based on the detection result, the surface temperature of the second heat exchanger 7 has a predetermined first threshold value (for example, −3). C)) or less. When the surface temperature of the second heat exchanger 7 is equal to or lower than the first threshold value, the control device 50 determines that the second heat exchanger 7 is frosted.

If it is determined in step S201 that frost has not formed (NO in S201), the process is temporarily returned to the main routine, and the processes of S200 and S201 are repeated. When it is determined in step S201 that frost has formed (YES in S201), the process proceeds to step S202.

In step S202, the control device 50 closes the solenoid valve 3a and opens the solenoid valve 3b, and operates the flow rate adjusting valve 10 so that the entire amount of the refrigerant flows into the second bypass flow passage B2. Further, the control device 50 switches the selection of the flow path switching valve 8b from the pipe C2 to the third bypass flow path, and fully opens the expansion valve 6d.

FIG. 16 is a diagram showing the flow of the refrigerant in the first stage (S202, S203) during defrosting of the second embodiment. As shown in FIG. 16, the refrigerant discharged from the compressor 1 passes through the second bypass passage B2, is decompressed by the second expansion valve 6c, and is sucked into the compressor 1 again.

Since the solenoid valve 3a is closed and the expansion valve 6d is open, a part of the refrigerant staying in the first heat exchanger 5 and the second heat exchanger 7 is sucked through the path indicated by the dashed arrow. Then, the temperature is raised in the loop indicated by the solid arrow.

Incidentally, in step S202, the first expansion valve 6a and the expansion valve 6d are fully opened. This is because when the defrosting operation is switched, the refrigerant remaining in the main circuit 30 is swiftly flowed through the loop indicated by the solid arrow including the second bypass flow passage B2. Further, the opening degree of the second expansion valve 6c is set to the same opening degree as that of the first expansion valve 6a during the heating operation before starting the defrosting operation. This is to prevent a state where the pressure difference before and after the second expansion valve 6c becomes small and the discharge pressure and discharge temperature of the refrigerant do not rise when the opening degree of the second expansion valve 6c is too large. Moreover, when the opening degree of the second expansion valve 6c is too small, the amount of the refrigerant flowing in on the suction side of the compressor 1 is prevented from becoming excessively small.

Referring again to FIGS. 13 and 14, in step S203, control device 50 obtains information for determining whether or not the discharge temperature of the refrigerant has reached the target value, and the discharge temperature of the refrigerant is It is determined whether or not the target value has been reached. Specifically, the control device 50 acquires the detection result of the temperature sensor 2a, and based on the detection result, the temperature of the refrigerant discharged from the compressor 1 is set to a second threshold value T2 (for example, 100). ℃) has been reached.

Note that, while repeating the processing of steps S202 and S203, the density of the sucked refrigerant may decrease with time. In that case, since the mass flow rate of the refrigerant sucked into the compressor 1 decreases, the discharge temperature of the refrigerant may not easily rise with time. Therefore, in step S203, when the rise in the discharge temperature of the refrigerant in a certain time interval (for example, 5 seconds) does not reach the predetermined third threshold value (for example, 10 ° C.), the operating frequency of the compressor 1 is changed. It may be controlled to increase. Alternatively, when the temperature of the refrigerant discharged from the compressor 1 does not reach a predetermined second threshold value (for example, 100 ° C.) even after a certain fixed time (for example, 60 seconds) has elapsed from the start of step S202, The process may proceed to step S204.

Next, in step S204, the control device 50 operates the flow rate adjusting valve 10 so that the entire amount of the refrigerant flows into the first bypass flow passage B1. At this time, the flow path switching valve 8b remains in the state where the third bypass flow path B3 is selected.

FIG. 17 is a diagram showing the flow of the refrigerant in the second stage of defrosting (S204, S205) according to the second embodiment. As shown in FIG. 17, the high-temperature and high-pressure refrigerant discharged from the compressor 1 flows through the first bypass passage B1 and is introduced into the second heat exchanger 7. The high-temperature high-pressure refrigerant defrosts the second heat exchanger 7. Further, the refrigerant flowing out from the second heat exchanger 7 is decompressed by the third expansion valve 6d and is again sucked into the compressor 1.

Next, in step S205, the control device 50 determines whether defrosting has progressed to a certain level. Specifically, the control device 50 causes the surface temperature of the second heat exchanger 7 to have a predetermined fourth threshold value (eg, −0.5 ° C.) based on the detection signal output from the temperature sensor 2b. It is determined whether or not the above. In addition, when the surface temperature of the second heat exchanger 7 is equal to or higher than the fourth threshold value, the control device 50 determines that the defrosting of the second heat exchanger 7 has progressed to a certain stage.

Next, in step S206, the control device 50 operates the flow rate adjusting valve 10 so that the refrigerant is distributed to the first bypass passage B1 and the second bypass passage B2.

FIG. 18 is a diagram showing the flow of the refrigerant in the third defrosting stage (S206, S207) according to the second embodiment. As shown in FIG. 18, a part of the refrigerant discharged from the compressor 1 flows through the first bypass passage B1 and is introduced into the second heat exchanger 7, and the defrosting of the second heat exchanger 7 continues. To be done. Further, the refrigerant flowing out from the second heat exchanger 7 is decompressed by the third expansion valve 6d and is again sucked into the compressor 1. Further, a part of the refrigerant discharged from the compressor 1 passes through the second bypass passage B2, is decompressed by the second expansion valve 6c, and is sucked into the compressor 1 again.

Next, the control device 50 determines in step S207 whether or not to finish the defrosting. Specifically, the control device 50 determines whether the surface temperature of the second heat exchanger 7 is equal to or higher than a predetermined third threshold value (for example, 0 ° C.) based on the detection signal output from the temperature sensor 2b. Determine whether or not. The control device 50 determines to finish the defrosting of the second heat exchanger 7 when the surface temperature of the second heat exchanger 7 is equal to or higher than the third threshold value.

When it is determined to finish the defrosting (YES in S207), the control device 50 sets the solenoid valve 3a to the open state, the solenoid valve 3b to the closed state, and selects the flow path switching valve 8b in the third step S208. The bypass flow path B3 is switched to the pipe C2. As a result, the steady heating operation in which the refrigerant flows is performed as shown in FIG.

Note that the defrosting time will be somewhat longer, but the processes of steps S204 and S205 may be omitted. Further, the process of step S204 and the process of step S206 may be interchanged.

Next, effects of the air conditioner 200 according to the second embodiment will be described.
FIG. 19 is a ph diagram showing the state of the refrigerant at the time when the refrigerant starts to be distributed to the second bypass flow passage B2 just before the end of defrosting in the second embodiment. The suction temperature Ts of the compressor 1 starts to increase according to the refrigerant distribution amount at this time. FIG. 20 is a ph diagram showing the state of the refrigerant at a point in time when a certain time has elapsed after the refrigerant was started to be distributed to the second bypass flow passage B2 in the second embodiment. The discharge temperature Td ′ also rises as the suction temperature Ts ′ rises after a certain time has elapsed. As a result, it becomes possible to return to the heating operation while the discharge temperature Td 'is high.

FIG. 21 is a diagram showing a temporal change in the discharge temperature of the refrigerant from the start of defrosting to the return of heating in the comparative example in which defrosting is performed by the cooling operation. In the comparative example, the compressor 1 is temporarily stopped and the four-way valve is switched at time t23 from the end of defrosting at time t22, the compressor 1 is restarted at time t24, and the discharge temperature reaches the target at time t25.

FIG. 22 is a diagram showing a temporal change in the discharge temperature of the refrigerant from the start of defrosting to the return to heating in the second embodiment. In the second embodiment, the refrigerant is distributed to both the first bypass flow passage B1 and the second bypass flow passage B2 at time t32 when the defrosting of the second heat exchanger 7 progresses by a certain stage by the end of the defrosting. It is possible to raise the discharge temperature of the refrigerant while continuing defrosting. Therefore, the discharge temperature of the refrigerant does not decrease even after the defrosting end determination is made at time t33, and the temperature of the refrigerant reaches the target discharge temperature at time t34.

Since it is not necessary to stop the compressor 1 and the discharge temperature of the refrigerant at the end of the defrosting operation is high, in the second embodiment, the time from the start of defrosting to the heating return is ΔT3 in comparison with the conventional case. It can be shortened to ΔT4, and a quick heating effect can be obtained when the heating operation is returned.

Embodiment 3.
FIG. 23 is a schematic configuration diagram showing the configuration of the air conditioner 300 according to the third embodiment.

Referring to FIG. 23, the air conditioner 300 includes a main circuit 30, a first bypass flow passage B1, a second bypass flow passage B2, and a first flow passage selection device 20B.

The air conditioner 300 further includes a compressor 1, a four-way valve 4, an extension pipe 9a, a first heat exchanger 5, an extension pipe 9b, a first expansion valve 6a, and a second heat exchanger 7. Prepare Usually, the first heat exchanger 5 is an indoor heat exchanger arranged indoors, and the second heat exchanger 7 is an outdoor heat exchanger arranged outdoors.

In the first bypass flow passage B1, the first expansion valve 6a side pipe of one of the first heat exchange unit 7a and the second heat exchange unit 7b of the second heat exchanger 7 is connected to the first flow passage selecting device 20B and the third pipe. It is connected to the discharge side pipe of the compressor 1 via the flow path selection device 20C.

The second bypass flow passage B2 connects the suction side pipe of the compressor 1 and the discharge side pipe of the compressor 1 via the first flow passage selecting device 20B.

The air conditioner 100 further includes a second expansion valve 6e. The second expansion valve 6e is provided in the middle of the second bypass flow passage B2 in FIG.

In the air conditioner 300 of the third embodiment shown in FIG. 23, the second heat exchanger 7 includes a first heat exchange section 7a and a second heat exchange section 7b. Regarding the arrangement of the first heat exchange section 7a and the second heat exchange section 7b, two outdoor heat exchangers having a small height may be arranged in the vertical direction, or the number of rows arranged in the wind direction may be set. Two small outdoor heat exchangers may be arranged one in the leeward direction and one in the leeward direction.

The air conditioner 300 is configured to connect the first bypass flow passage B1 and the first expansion valve 6a to either the first heat exchange portion 7a or the second heat exchange portion 7b, and the third flow passage selection device 20C. Is further provided.

The second flow path selection device 20C includes

solenoid valves

3c, 3d, 3e, 3f. The solenoid valve 3c opens and closes the flow path connecting the first expansion valve 6a and the first heat exchange section 7a. The solenoid valve 3d opens and closes a flow path that connects the first expansion valve 6a and the second heat exchange unit 7b. The solenoid valve 3e opens and closes the flow path connecting the first bypass flow path B1 and the first heat exchange section 7a. The solenoid valve 3f opens and closes the flow path that connects the first bypass flow path B1 and the second heat exchange unit 7b.

The first flow path selection device 20B is configured to selectively flow the refrigerant discharged from the compressor 1 into at least one of the first heat exchanger 5, the first bypass flow path B1, and the second bypass flow path B2. To be done. In the third embodiment, the first flow path selection device 20B selectively causes the refrigerant discharged from the compressor 1 to flow through either the first heat exchanger 5 or the branch pipe B0, and also flows through the branch pipe B0. Is distributed to the first bypass flow passage B1 and the second bypass flow passage B2.

Specifically, in the third embodiment, the first flow path selection device 20B distributes the refrigerant to the main circuit 30 and the second bypass flow path B2 during the defrosting operation (FIGS. 27 and 31), Then, while flowing the refrigerant through the main circuit 30 to either the first heat exchange section 7a or the second heat exchange section 7b, either the first heat exchange section 7a or the second heat exchange section 7b through the first bypass flow passage B1. The refrigerant is passed to the other side (FIGS. 28 and 32).

The third flow passage selecting device 20C connects the first bypass flow passage B1 to either one of the first heat exchange portion 7a and the second heat exchange portion 7b and sets the first expansion valve 6a to the first expansion valve 6a during the defrosting operation. It is connected to either the other of the 1st heat exchange part 7a and the 2nd heat exchange part 7b (FIG. 28, FIG. 32).

The air conditioner 300 of the third embodiment has the same basic configuration as that of the first embodiment, but has a flow rate adjusting valve 10b in the main circuit 30, the expansion valve 6b is removed, the solenoid valve 3c, the solenoid. The valve 3d is provided, the second heat exchanger 7 is provided with the divided first heat exchange portion 7a and second heat exchange portion 7b, and the first heat exchange portion 7a and the second heat exchange portion 7b are provided, respectively. Having

temperature sensors

2c and 2d, having

expansion valves

6f and 6g provided corresponding to the first heat exchanging section 7a and the second heat exchanging section 7b, respectively, and having an electromagnetic valve at the outlet of the first bypass passage B1. They are different in that they have a valve 3e and a solenoid valve 3f, and that they have a solenoid valve 6e in the middle of the second bypass flow passage B2. The same components as those in the first embodiment are designated by the same reference numerals.

Also, a fan for blowing air is provided on each of the air outlet side and the air inlet side of the second heat exchanger 7 and the first heat exchanger 5 (not shown). Each fan may be a line flow fan, a propeller fan, a turbo fan, a sirocco fan, or the like. Further, a configuration may be used in which a plurality of fans are used for one heat exchanger. Further, the first heat exchange section 7a and the second heat exchange section 7b may be arranged side by side in the horizontal direction or may be arranged side by side in the vertical direction. Further, the above-mentioned configuration is the minimum component capable of cooling and heating operation, and a gas-liquid separator, a receiver, an accumulator and the like may be further added to the main circuit 30.

The temperature sensor 2c included in the first heat exchange unit 7a and the temperature sensor 2d included in the second heat exchange unit 7b are provided at a position on the outlet side of the refrigerant during heating operation (point P10 side). Has been.

Note that, as in the first embodiment, the type of refrigerant enclosed in the air conditioner is not limited. As the refrigerant, HFC refrigerant, HFO refrigerant, HC refrigerant, or non-azeotropic mixed refrigerant may be enclosed.

Next, the operation of the air conditioner 300 according to the third embodiment will be described.
FIG. 24 is a flowchart for explaining the operation of each element during the defrosting operation of the first heat exchange unit 7a in the third embodiment. FIG. 25 is a diagram showing states of elements in each processing of the flowchart of FIG. FIG. 25 shows the open / closed state of the

solenoid valves

3c, 3d, 3b, 3e, 3f in each process of FIG. It is shown.

The processes of the frost formation determination (S301), the constant discharge temperature arrival determination (S303), and the defrosting end determination (S305) of the flowchart of FIG. 24 are the same as those of S101, S103, and S105 of the first embodiment, respectively. The processing (S300, S302, S304, S306) involving the operation of is different from that of the first embodiment.

Note that the control described in FIGS. 24 and 25 is a control for defrosting the first heat exchange unit 7a from the heating operation, and in the case of defrosting the second heat exchange unit 7b, the control illustrated in FIGS. This will be described with reference to FIG.

When the heating operation is started, in step S300, the control device 50 causes the solenoid valve 3c to be open, the solenoid valve 3d to be open, the solenoid valve 3b to be closed, the solenoid valve 3e to be closed, and the solenoid valve 3f to be closed. Therefore, the flow path switching valve 8 selects the first bypass flow path B1, and the flow rate adjustment valve 10b controls these valves so that the entire amount of the refrigerant flows into the main circuit 30.

FIG. 26 is a diagram showing a refrigerant flow during heating (S300, S301, S306) according to the third embodiment. As shown in FIG. 26, the refrigerant is discharged from the compressor 1, and the flow rate adjusting valve 10b, the four-way valve 4, the first heat exchanger 5, the first expansion valve 6a, the second heat exchanger 7, the four-way valve 4 are provided. And then returns to the compressor 1. In the second heat exchanger 7, the refrigerant is divided into two by the flow path selection device 20C, and is parallel to the path of the first heat exchange section 7a and the expansion valve 6f and the path of the second heat exchange section 7b and the expansion valve 6g. And flow at the point P10.

24 and 25 again, in step S301, the control device 50 acquires information for determining whether the first heat exchange unit 7a is frosted, and then the first heat exchange unit. It is determined whether 7a is frosted. Specifically, the control device 50 acquires the detection result of the temperature sensor 2c, and based on the detection result, the surface temperature of the first heat exchanging portion 7a has a predetermined first threshold value (for example, − 3 ° C.) or less is determined. The controller 50 determines that the first heat exchange unit 7a is frosted when the surface temperature of the first heat exchange unit 7a is equal to or lower than the first threshold value. When it is determined that frost is formed, the control device 50 advances the process to step S302. If it is determined that frost has not formed, the processes of steps S302 to S306 are not executed, and the processes of steps S300 and S301 are repeated.

In step S302, in the control device 50, the electromagnetic valve 3c is closed, the electromagnetic valve 3b is opened, the flow path switching valve 8 selects the second bypass flow path B2, and the flow rate adjustment valve 10 supplies the refrigerant to the main circuit 30. Each valve is controlled so as to be distributed to the pipe C0 and the second bypass flow passage B2. The

solenoid valves

3e and 3f are maintained in the state of step S300 and are both closed. Further, the state of step S300 is maintained, and the solenoid valve 3d is controlled to be in the open state.

FIG. 27 is a diagram showing a refrigerant flow in the first stage (S302, S303) during the defrosting operation of the first heat exchange section 7a. As shown in FIG. 27, a part of the refrigerant discharged from the compressor 1 flows to the main circuit 30 and the second heat exchange section 7b to continue the heating operation, and another part of the refrigerant flows to the second bypass flow. After passing through the path B2, the pressure is reduced by the expansion valve 6e and is again sucked into the compressor 1.

Note that the opening degree of the expansion valve 6e is set to the same opening degree as that of the expansion valve 6a in step S302. This is because the refrigerant flowing through the pipe C1 of the main circuit 30 and the refrigerant flowing through the second bypass passage B2 are merged at the same pressure at the point P11.

Subsequently, in step S303, the control device 50 acquires information for determining whether the discharge temperature of the refrigerant has reached the target value, and whether the discharge temperature of the refrigerant has reached the target value. To determine. Specifically, the control device 50 acquires the detection result of the temperature sensor 2a, and based on the detection result, the temperature of the refrigerant discharged from the compressor 1 is set to a second threshold value T2 (for example, 100). ℃) is reached. When the discharge temperature of the refrigerant has reached the second threshold value T2 in step S303, the control device 50 advances the process to step S304.

Note that in steps S302 and S303, the density of the refrigerant sucked into the compressor 1 may decrease with time. In that case, since the mass flow rate of the refrigerant sucked into the compressor 1 decreases, the discharge temperature of the refrigerant may not easily rise with time. Therefore, in step S303, when the increase in the discharge temperature of the refrigerant at a constant time interval (for example, 5 second intervals) does not reach the predetermined third threshold value (for example, 10 ° C.), the operating frequency of the compressor 1 May be controlled. Alternatively, the temperature of the refrigerant discharged from the compressor 1 may have reached a predetermined second threshold value (eg, 100 ° C.) even after a certain period of time (eg, 60 seconds) has elapsed from the time when the process of step S302 was started. If not, the process may proceed to step S304.

In step S304, the control device 50 controls each valve so that the solenoid valve 3e is opened and the passage switching valve 8 selects the first bypass passage B1. The state of step S302 is maintained for the

solenoid valves

3b, 3c, 3d, 3f and the flow rate adjusting valve 10b.

FIG. 28 is a diagram showing the flow of the refrigerant in the second stage (S304, S305) during the defrosting operation of the first heat exchange section 7a. As shown in FIG. 28, a part of the high-temperature and high-pressure refrigerant discharged from the compressor 1 flows through the first bypass passage B1 and is introduced into the first heat exchange section 7a. In this way, the first heat exchange section 7a is defrosted. The refrigerant flowing out of the first heat exchange section 7a is decompressed by the expansion valve 6f.

Note that in step S304, the control device 50 sets the opening degree of the expansion valve 6f to be the same as the opening degree of the expansion valve 6a, and sets the expansion valve 6g to full open. This is because the refrigerant of the main circuit 30 flowing through the second heat exchange section 7b and the refrigerant used for defrosting flowing through the first heat exchange section 7a have the same pressure and are merged at the point P10.

Next, the control device 50 determines in step S305 whether or not to finish the defrosting. Specifically, the control device 50 determines whether the surface temperature of the first heat exchange unit 7a is equal to or higher than a predetermined third threshold value (for example, 0 ° C.) based on the detection signal output from the temperature sensor 2c. Determine whether or not. The control device 50 determines to finish the defrosting when the surface temperature of the first heat exchange section 7a is equal to or higher than the third threshold value. When determining to end the defrosting, the control device 50 advances the process to step S306.

In step S306, the control device 50 causes the solenoid valve 3c to be in the open state, the solenoid valve 3d to be in the open state, the solenoid valve 3b to be in the closed state, and the solenoid valve 3e to be in the closed state. Control each valve so that At this time, the flow path switching valve 8 remains unchanged. As a result, the refrigerant flows as shown in FIG. 26, and the steady heating operation is performed.

Next, the operation of performing the defrosting operation on the second heat exchange unit 7b will be described.
FIG. 29 is a flow chart for explaining the operation of each element during the defrosting operation of the second heat exchange section 7b in the third embodiment. FIG. 30 is a diagram showing states of elements in each processing of the flowchart of FIG. In FIG. 30, the open / closed states of the

solenoid valves

3c, 3d, 3b, the solenoid valve 3e, and the solenoid valve 3f in each process of FIG. The distribution state is shown.

In the flowchart of FIG. 29, steps S301 to S305 are replaced with steps S301A to S305A in the flowchart of FIG.

When the heating operation is started, in step S300, the control device 50 causes the solenoid valve 3c to be open, the solenoid valve 3d to be open, the solenoid valve 3b to be closed, the solenoid valve 3e to be closed, and the solenoid valve 3f to be closed. Therefore, the flow path switching valve 8 selects the first bypass flow path B1, and the flow rate adjustment valve 10b controls these valves so that the entire amount of the refrigerant flows into the main circuit 30. As a result, the refrigerant flows as shown in FIG.

Subsequently, in step S301A, the control device 50 acquires information for determining whether or not the second heat exchange unit 7b is frosted, and determines whether or not the second heat exchange unit 7b is frosted. To judge. Specifically, the control device 50 acquires the detection result of the temperature sensor 2d, and based on the detection result, the surface temperature of the second heat exchanging portion 7b has a predetermined first threshold value (for example, − 3 ° C.) or less is determined. The control device 50 determines that the second heat exchange unit 7b is frosted when the surface temperature of the second heat exchange unit 7b is equal to or lower than the first threshold value. In this case, the control device 50 advances the process to step S302A.

In step S302A, in the control device 50, the electromagnetic valve 3d is closed, the electromagnetic valve 3b is opened, the flow path switching valve 8 selects the second bypass flow path B2, and the flow rate adjustment valve 10 supplies the refrigerant to the main circuit 30. Each valve is controlled so as to be distributed to the pipe C0 and the second bypass flow passage B2. The

solenoid valves

3e and 3f are maintained in the state of step S300 and are both closed. Further, the state of step S300 is maintained and the solenoid valve 3c is controlled to be in the open state.

FIG. 31 is a diagram showing a refrigerant flow in the first stage (S302A, S303A) during the defrosting operation of the second heat exchange section 7b. As shown in FIG. 31, a part of the refrigerant discharged from the compressor 1 flows to the main circuit 30 and the first heat exchange section 7a to continue the heating operation, and another part of the refrigerant flows to the second bypass flow. After passing through the path B2, the pressure is reduced by the expansion valve 6e and is again sucked into the compressor 1.

Note that the opening degree of the expansion valve 6e is set to the same opening degree as that of the expansion valve 6a in step S302A. This is because the refrigerant flowing through the pipe C1 of the main circuit 30 and the refrigerant flowing through the second bypass passage B2 are merged at the same pressure at the point P11.

Subsequently, in step S303A, the control device 50 acquires information for determining whether or not the discharge temperature of the refrigerant has reached the target value, and determines whether the discharge temperature of the refrigerant has reached the target value. To determine. Specifically, the control device 50 acquires the detection result of the temperature sensor 2a, and based on the detection result, the temperature of the refrigerant discharged from the compressor 1 is a second threshold value set in advance (for example, 100 ° C.). ) Is reached. When the discharge temperature of the refrigerant has reached the second threshold value in step S303A, the control device 50 advances the process to step S304A.

Note that, in steps S302A and S303A, the density of the refrigerant sucked into the compressor 1 may decrease with time. In that case, since the mass flow rate of the refrigerant sucked into the compressor 1 decreases, the discharge temperature of the refrigerant may not easily rise with time. For this reason, in step S303A, when the refrigerant discharge temperature rise at a constant time interval (for example, 5 second intervals) is less than a predetermined third threshold value (for example, 10 ° C.), the operating frequency of the compressor 1 is increased. You may control. Alternatively, the temperature of the refrigerant discharged from the compressor 1 reaches a predetermined second threshold value (for example, 100 ° C.) even after a certain fixed time (for example, 60 seconds) has elapsed from the time when the process of step S302A was started. If not, the process may proceed to step S304A.

In step S304A, the control device 50 controls each valve so that the solenoid valve 3f is opened and the passage switching valve 8 selects the first bypass passage B1. For the

solenoid valves

3b, 3c, 3d, 3e and the flow rate adjusting valve 10b, the state of step S302A is maintained.

FIG. 32 is a diagram showing the flow of the refrigerant in the second stage (S304A, S305A) during the defrosting operation of the second heat exchange section 7b. As shown in FIG. 32, a part of the high-temperature high-pressure refrigerant discharged from the compressor 1 flows through the first bypass flow passage B1 and is introduced into the second heat exchange section 7b. In this way, the second heat exchange section 7b is defrosted. The refrigerant flowing out from the second heat exchange section 7b is decompressed by the expansion valve 6g.

Note that in step S304A, the control device 50 sets the opening degree of the expansion valve 6g to be the same as the opening degree of the expansion valve 6a, and sets the solenoid valve 6f to fully open. This is because the refrigerant of the main circuit 30 flowing through the first heat exchange section 7a and the refrigerant used for defrosting flowing through the second heat exchange section 7b have the same pressure and are merged at the point P10.

Next, the control device 50 determines in step S305A whether or not to finish the defrosting. Specifically, the control device 50 determines whether the surface temperature of the second heat exchange section 7b is equal to or higher than a predetermined third threshold value (for example, 0 ° C.) based on the detection signal output from the temperature sensor 2d. Determine whether or not. The control device 50 determines that the defrosting is ended when the surface temperature of the second heat exchange section 7b is equal to or higher than the third threshold value. When determining to end the defrosting, the control device 50 advances the process to step S306.

In step S306, the control device 50 causes the solenoid valve 3c to be in the open state, the solenoid valve 3d to be in the open state, the solenoid valve 3b to be in the closed state, and the solenoid valve 3e to be in the closed state. Control each valve so that As a result, the refrigerant flows as shown in FIG. 26, and the steady heating operation is performed.

As described above, according to the processes of the flowcharts shown in FIGS. 24 and 29, in the third embodiment, when only one of the first heat exchange section 7a and the second heat exchange section 7b is frosted, the frosted heat exchange is performed. Defrost parts. However, when two heat exchange parts are frosted at the same time, defrosting is performed with the following priority.

First, when two heat exchange units with a small height are arranged in the vertical direction of the outdoor unit, defrosting is performed preferentially from the heat exchange unit that is higher in the vertical direction. If this is reversed, the water generated by the defrosting of the upper heat exchange section will be applied to the lower heat exchange section that has completed defrosting, so re-freezing may occur on the surface of the lower heat exchange section. Because there is. In addition, when two heat exchange units having a small number of rows in the wind direction are arranged on the windward side and one on the leeward side, defrosting is preferentially performed from the heat exchange unit on the windward side. This is because the heat exchange section on the windward side is more likely to frost than the heat exchange section on the leeward side, and the heat exchange section on the leeward side does not need to be defrosted in many cases. In the following description, the heat exchanging part that preferentially defrosts in this way will be described as the first heat exchanging part 7a.

FIG. 33 is a flowchart for explaining an example of a process of defrosting the first heat exchanging unit 7a prior to the second heat exchanging unit 7b in the third embodiment. Note that the numbers of the respective steps are given the same numbers as the steps of FIGS. 24 and 29, and detailed description will not be repeated.

Referring to FIG. 33, first, in step S300, control device 50 causes the refrigerant to flow in parallel to first heat exchange unit 7a and second heat exchange unit 7b, and performs normal heating operation. Then, the control device 50 determines whether or not frost is formed on the first heat exchange unit 7a in step S301.

When it is determined in step S301 that there is frost formation (YES in S301), in steps S302 and S303, the control device 50 continues the heating using the second heat exchange section 7b with a part of the refrigerant while remaining. The refrigerant temperature increasing process is performed to cause the refrigerant to flow through the second bypass flow path B2 and circulate to increase the temperature.

After that, in steps S304 and S305, the control device 50 continues the heating using the second heat exchanging unit 7b with a part of the refrigerant, and the remaining refrigerant with the first heat exchanging unit passing through the first bypass flow passage B1. 7a to defrost the first heat exchange section 7a.

In step S301, when it is determined that there is no frost formation, and when the processes of steps S304 and S305 are executed and the defrosting of the first heat exchange unit 7a is completed, subsequently in step S301A, the control device 50 causes the second heat The presence or absence of frost on the exchange section 7b is determined.

When it is determined that there is frost formation in step S301A (YES in S301A), in step S302A and S303A, the control device 50 continues heating while using the first heat exchange section 7a with some of the refrigerant, while remaining. The refrigerant temperature increasing process is performed to cause the refrigerant to flow through the second bypass flow path B2 and circulate to increase the temperature.

After that, in steps S304A and S305A, the control device 50 continues the heating using the first heat exchange unit 7a with a part of the refrigerant, and the remaining refrigerant with the second heat exchange unit via the first bypass flow passage B1. 7b to defrost the second heat exchange section 7b.

If it is determined in step S301A that there is no frost formation, or if the processing of steps S304A and S305A has been executed and the defrosting of the second heat exchange section 7b has been completed, then the processing of step S306 proceeds. In step S306, the control device 50 changes the setting of each valve so that the refrigerant flows in parallel to the first heat exchange section 7a and the second heat exchange section 7b so that the normal heating operation is performed, and the processing is performed. Return to the main routine.

Next, effects of the air conditioner according to the third embodiment having the above configuration will be described.
In the third embodiment, during the defrosting operation, the refrigerant is distributed to the main circuit 30 and the second bypass flow passage B2, and then the refrigerant is distributed to the main circuit 30 and the first bypass flow passage B1 to flow the refrigerant. The heating operation can be continued even during the defrosting operation.

Also, since the heating operation can be continued even during the defrosting operation, it is possible to reduce the decrease in room temperature during the defrosting operation and improve comfort.

Finally, the effects of the air conditioners according to the first to third embodiments will be collectively described.
The air conditioner of the present disclosure includes a first bypass flow path B1 that connects the discharge side of the compressor 1 and the heating-side inlet side of the outdoor second heat exchanger 7, the discharge side of the compressor 1, and the suction side of the compressor 1. And a second bypass flow path B2 connecting the two. When the temperature of the outdoor second heat exchanger 7 becomes equal to or lower than the predetermined first threshold value, the control device 50 operates the flow

path selection devices

20, 20A, 20B to bypass the refrigerant to the second bypass. Defrosting is performed by causing the refrigerant to flow through the flow path B2 and then through the first bypass flow path B1 to the outdoor second heat exchanger 7.

By flowing the refrigerant to the second bypass flow passage B2, the discharge temperature of the refrigerant in the compressor 1 can be made higher than usual.

In addition, by increasing the discharge temperature of the refrigerant, when the flow

path selecting devices

20, 20A, 20B are switched to the first bypass flow path B1, the temperature of the refrigerant is higher than that during the normal heating operation, and the outdoor first. 2 can be flowed to the heat exchanger 7.

Further, since the defrosting operation is performed in a state where the temperature of the refrigerant is higher than normal, the temperature difference between the refrigerant and the frosted heat exchanger becomes large in the entire second heat exchanger 7 outside the unit, and Since the amount of heat exchange is increased, defrosting can be performed in a short time.

In addition, the above-described effect that the discharge temperature of the refrigerant can be increased and defrosting can be performed in a short time depends on the kind of the refrigerant enclosed in the air conditioner, such as HFC refrigerant, HFO refrigerant, HC refrigerant, and non-azeotropic mixed refrigerant. Although not available, the total GWP value in the cycle can be reduced by using a refrigerant having a low GWP (for example, R290 (GWP3) which is one of the HC refrigerants).

Also, when the non-azeotropic mixed refrigerant is enclosed in the air conditioner, frost is likely to form on the refrigerant inlet side of the outdoor heat exchanger during heating. On the other hand, in the air conditioner of the present embodiment, a high-pressure / high-temperature refrigerant gas can flow to the heating refrigerant inlet side of the second heat exchanger 7 through the first bypass passage B1. Therefore, the temperature difference between the refrigerant and the frosted heat exchanger on the refrigerant inlet side of the second heat exchanger 7 during heating increases, and the amount of heat exchange per unit time increases, so defrosting is performed in a short time. be able to.

Further, in the air conditioner of the present embodiment, defrosting is performed in a gas region in a more overheated state as compared with general defrosting by switching the cooling operation. For this reason, the degree of superheat (SH) of the refrigerant sucked into the compressor 1 becomes large, and liquid back to the compressor 1 does not easily occur, so that the reliability of the compressor 1 can be improved.

Further, in the air conditioner according to the present embodiment, the refrigerant does not pass through the

extension pipes

9a and 9b, the first heat exchanger 5 in the room, and the like during the defrosting operation, as compared with the general defrosting operation by switching the cooling operation. Therefore, heat dissipation loss can be reduced.

In addition, in the air conditioner of the present embodiment, the defrosting operation can be performed without the refrigerant passing through the first heat exchanger 5 in the room, as compared with the general defrosting operation by switching the cooling operation. No heat absorption occurs in the heat exchanger 5, and it is possible to reduce the decrease in room temperature during the defrosting operation.

In addition, in the air conditioner of the present embodiment, when starting the defrosting operation, the flow

path selection devices

20, 20A, 20B are operated to prevent the refrigerant from flowing into the main circuit 30, and to transfer the refrigerant to the second bypass flow path B2. Then, the refrigerant is allowed to flow to the outdoor second heat exchanger 7 through the first bypass flow path B1. This eliminates the need to switch the four-way valve during defrosting operation, and it is not necessary to stop the compressor in order to create the pressure state required to switch the four-way valve. You can

Further, when the defrosting operation is finished and the operation is returned to the heating operation, the four-way valve is switched when the heating operation is returned by operating the flow

path selection devices

20, 20A, 20B and flowing the entire amount of the refrigerant into the main circuit 30. Absent. For this reason, it is not necessary to stop the compressor in order to create the pressure state necessary for switching the four-way valve.Therefore, it is necessary to shorten the time to return to heating operation as compared to the defrosting operation by switching cooling operation in general. You can

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

1 compressor, 2a, 2b, 2c, 2d temperature sensor, 3a, 3b, 3c, 3d, 3e, 3f solenoid valve, 4 four-way valve, 5 first heat exchanger, 6a, 6b, 6c, 6d, 6e, 6f , 6g expansion valve, 7 second heat exchanger, 7a 1st heat exchange section, 7b 2nd heat exchange section, 8 switching valve, 8b, 20, 20A, 20B, 20C selector, 9a,

9b extension pipes

10, 10b flow control valve, 30 main circuit, 50 control device, 51 processor, 52 memory, 53 input / output interface, 100, 200, 300 air conditioner, B0 branch pipe, B1, B2, B3 flow path, C0, C1, C2 piping .

Claims

A main circuit in which the refrigerant circulates in the order of the compressor, the first heat exchanger, the first expansion valve, and the second heat exchanger during the heating operation,
A first bypass flow passage that connects the first expansion valve side pipe of the second heat exchanger and the discharge side pipe of the compressor;
A second bypass passage that connects the suction side pipe of the compressor and the discharge side pipe of the compressor;
A first flow path selection device configured to selectively pass the refrigerant discharged by the compressor through at least one of the first heat exchanger, the first bypass flow path, and the second bypass flow path. With and
During the heating operation, the first flow path selection device selects at least the first heat exchanger,
An air conditioner in which, during the defrosting operation, the first flow path selection device selects at least the first bypass flow path after selecting at least the second bypass flow path.
During the defrosting operation, the first flow path selecting device selects the second bypass flow path and deselects the first bypass flow path and the first heat exchanger, and then the first bypass flow path. The air conditioner according to claim 1, wherein a path is selected and the second bypass flow path and the first heat exchanger are not selected.
The air conditioner according to claim 1 or 2, further comprising a second expansion valve arranged in the middle of the second bypass flow passage or between the second bypass flow passage and a suction side pipe of the compressor. .
The first flow path selection device,
A first solenoid valve provided in a conduit between the discharge side of the compressor and the first heat exchanger;
A second solenoid valve provided in a branch pipe from the main circuit shared by the discharge side of the compressor, the first bypass passage and the second bypass passage,
The air conditioner according to any one of claims 1 to 3, further comprising: a flow path switching valve that connects the branch pipe to either one of the first bypass flow path and the second bypass flow path.
During the defrosting operation, the first flow path selecting device selects the second bypass flow path and deselects the first bypass flow path and the first heat exchanger, and then the first bypass flow path. The air conditioner according to claim 1, wherein the first heat exchanger is deselected while selecting a passage and the second bypass passage.
A second expansion valve disposed in the middle of the second bypass flow path,
In the heating operation, a third bypass flow path that branches from the first pipe through which the refrigerant that has passed through the second heat exchanger flows to the suction side of the compressor,
A third expansion valve disposed in the middle of the third bypass flow path,
And a second flow path selecting device,
The second flow passage selection device selectively connects the second pipe or the third bypass flow passage that connects the first pipe to the suction side of the compressor without passing through the third bypass flow passage. The air conditioner according to claim 1 or 5.
The second heat exchanger,
Including a first heat exchange section and a second heat exchange section,
In the defrosting operation, the first flow path selecting device distributes and flows the refrigerant to the main circuit and the second bypass flow path, and then flows the refrigerant to the first heat exchange unit through the main circuit. The air conditioner according to claim 1, wherein the refrigerant flows through the second heat exchange unit through the first bypass flow path.
Further comprising a third flow passage selection device configured to connect the first bypass flow passage and the first expansion valve to either the first heat exchange unit or the second heat exchange unit,
During the defrosting operation, the third flow path selecting device connects the first bypass flow path to either one of the first heat exchange section and the second heat exchange section, and connects the first expansion valve to the first expansion valve. The air conditioner according to claim 7, which is connected to the other one of the first heat exchange section and the second heat exchange section.
The air conditioner according to any one of claims 1 to 8, wherein the refrigerant is an HC refrigerant.
The air conditioner according to any one of claims 1 to 8, wherein the refrigerant is a non-azeotropic mixed refrigerant.