JP7034325B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner.

Conventionally, a refrigeration cycle device provided with a bypass circuit connecting a compressor discharge side and an outdoor heat exchanger inlet side is known (Patent Document 1: Japanese Patent Application Laid-Open No. 2009-145032). This refrigeration cycle device can quickly defrost by flowing the refrigerant discharged from the compressor to the outdoor heat exchanger through the bypass circuit when the outdoor heat exchanger is frosted.

JP-A-2009-14503

The refrigerating cycle device described in JP-A-2009-140532 shortens the defrosting time by flowing a refrigerant through an bypass flow path connecting a compressor discharge side and an outdoor heat exchanger inlet side to an outdoor heat exchanger. Can be done. 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. Since the amount of heat exchange is reduced, there is a problem that the time required for defrosting cannot be shortened.

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

The air conditioner according to the present disclosure includes a main circuit in which a compressor circulates in the order of a compressor, a first heat exchanger, a first expansion valve, and a second heat exchanger during heating operation, and a second heat exchanger. 1 The first bypass flow path that communicates the expansion valve side pipe and the discharge side pipe of the compressor, the second bypass flow path that communicates the suction side pipe of the compressor and the discharge side pipe of the compressor, and the compressor. A first flow path selection device configured to selectively pass the discharged refrigerant through at least one of a first heat exchanger, a first bypass flow path, and a second bypass flow path is provided. 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, since the refrigerant is introduced into the heat exchanger frosted by the bypass flow path after the temperature of the refrigerant is raised as compared with that during normal heating, the defrosting time is shortened.

It is a schematic block diagram which shows the structure of the air conditioner 100 which concerns on Embodiment 1. FIG. It is a flowchart for demonstrating operation of each element at the time of defrosting operation in Embodiment 1. FIG. 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. FIG. It is a figure which shows the flow of the refrigerant in the 1st stage (S102, S103) at the time of defrosting of Embodiment 1. FIG. It is a figure which shows the flow of the refrigerant in the 2nd stage (S104, S105) at the time of defrosting of Embodiment 1. FIG. 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 in the cooling operation direction. It is a ph diagram which shows the state of the refrigerant at the time of defrosting operation in Embodiment 1. FIG. It is a figure which superimposed and showed the temperature distribution of the refrigerant in the defrosting operation of the comparative example in the 2nd heat exchanger 7 and the defrosting operation of Embodiment 1. FIG. It is a figure which shows the difference of the time from the frost formation determination to the start of a defrosting operation in each of the comparative example and the first embodiment. It is a figure which shows the difference of the time from the end of defrosting to the return to heating in each of a comparative example and the first embodiment. It is a schematic block diagram which shows the structure of the air conditioner 200 which concerns on Embodiment 2. FIG. It is a flowchart for demonstrating operation of each element at the time of defrosting operation in Embodiment 2. 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 1st stage (S202, S203) at the time of defrosting of Embodiment 2. It is a figure which shows the flow of the refrigerant in the 2nd stage (S204, S205) at the time of defrosting of Embodiment 2. It is a figure which shows the flow of the refrigerant in the 3rd stage (S206, S207) at the time of defrosting of Embodiment 2. FIG. 2 is a ph diagram showing the state of the refrigerant at the time when the refrigerant is started to be distributed to the second bypass flow path B2 just before the end of defrosting in the second embodiment. FIG. 2 is a ph diagram showing a state of the refrigerant at a time when a certain time has elapsed after the start of distribution of the refrigerant to the second bypass flow path B2 in the second embodiment. It is a figure which shows the time change of the discharge temperature of the refrigerant from the start of defrosting to the return to heating of the comparative example which performs defrosting by a cooling operation. It is a figure which shows the temporal change of the discharge temperature of the refrigerant from the start of defrosting to the return to heating in Embodiment 2. FIG. It is a schematic block diagram which shows the structure of the air conditioner 300 which concerns on Embodiment 3. FIG. It is a flowchart for demonstrating the operation of each element at the time of defrosting operation of the 1st heat exchange part 7a in Embodiment 3. FIG. 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. FIG. 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 stage (S304, S305) at the time of the defrosting operation of the 1st heat exchange part 7a. It is a flowchart for demonstrating the operation of each element at the time of defrosting operation of the 2nd heat exchange part 7b in Embodiment 3. FIG. 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 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 in the 2nd stage (S304A, S305A) at the time of the defrosting operation of the 2nd heat exchange part 7b. It is a flowchart for demonstrating an example of the process of defrosting the 1st heat exchange part 7a with priority over the 2nd heat exchange part 7b in Embodiment 3.

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 respective embodiments. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

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

With reference to FIG. 1, the air conditioner 100 includes a main circuit 30, a first bypass flow path B1, a second bypass flow path B2, and a first flow path selection 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. Be prepared. Normally, 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 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, and the four-way valve in the main circuit 30. It circulates in the order of 4, and returns to the compressor 1.

The first bypass flow path B1 communicates the point P2 of the first expansion valve 6a side pipe of the second heat exchanger 7 with the point P1 of the discharge side pipe of the compressor 1.

The second bypass flow path B2 communicates the point P3 of the suction side pipe of the compressor 1 with 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 by the compressor 1 to at least one of the first heat exchanger 5, the first bypass flow path B1, and the second bypass flow path B2. Will be done. In the first embodiment, the first flow path selection device 20 selectively selects the refrigerant discharged by the compressor 1 into one of the first heat exchanger 5, the first bypass flow path B1, and the second bypass flow path B2. It is configured to pass through.

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

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

The branch pipe B0 and the bypass flow path 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. To. Further, the point P3 and the point P1 between the four-way valve 4 and the second expansion valve 6b are connected by the branch pipe B0 and the bypass flow path B2.

Further, although not shown, a fan for blowing air is provided on the outlet side or the 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. Further, 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 by 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, which is the refrigerant outlet of the second heat exchanger 7, during the heating operation. The control device 50 includes a compressor 1, a four-way valve 4, a first expansion valve 6a, a flow path selection device 20, a second expansion valve 6b, and not shown, based on the detected temperatures of the temperature sensors 2a and 2b and a command from the user. 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, an application program, and various types of data.

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

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, a non-azeotropic mixed refrigerant, or the like may be encapsulated.

The air conditioner 100 having the configuration shown in FIG. 1 may frost on the second heat exchanger 7 arranged outdoors during the heating operation. A defrosting operation is performed 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 dissipated and condensed by the first heat exchanger 5.

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 path B2 then flows from the first bypass flow path B1 into the second heat exchanger 7, and defrosting is executed.

Next, the operation of the air conditioner 100 according to the first embodiment of 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 process of the flowchart of FIG. 2.

When the heating operation is started, in step S100, the control device 50 sets the solenoid valve 3a in the open state, the solenoid valve 3b in the closed state, and causes the flow path switching valve 8 to select the second bypass flow path B2. Control the valve.

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

With reference to FIGS. 2 and 3 again, in step S101, the control device 50 acquires information for determining whether or not the second heat exchanger 7 is frosted, and obtains information for determining whether or not the second heat exchanger 7 is frosted. It is determined whether or not 7 is frosted. Specifically, the control device 50 acquires the detection result of the temperature sensor 2b, and the surface temperature of the second heat exchanger 7 is set to a predetermined first threshold value (for example,-) based on the detection result. 3 ° C.) or less is determined. The control device 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 frost has not formed (NO in S101), the process is once returned to the main routine, and the processes of S100 and S101 are repeated again. If 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 stage (S102, S103) at the time of defrosting 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 flow path B2, is depressurized by the second expansion valve 6b, and is sucked into the compressor 1 again. 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 by the path indicated by the broken line arrow, and is indicated by the solid line arrow. The temperature is raised in the loop.

In step S102, the control device 50 fully opens the expansion valve 6a. This is to promptly flow the refrigerant remaining in the main circuit into the loop indicated by the solid arrow including the second bypass flow path B2 when switching to the defrosting operation. 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 in which the pressure difference becomes small before and after the second expansion valve 6b and the discharge pressure and the discharge temperature of the refrigerant do not rise when the opening degree of the second expansion valve 6b is too large. Further, this is to prevent the amount of the refrigerant flowing into the suction side of the compressor 1 from becoming excessively small when the opening degree of the second expansion valve 6b is too small.

With reference to FIGS. 2 and 3 again, the control device 50 acquires information for determining whether or not the discharge temperature of the refrigerant has reached the target value in step S103, and the discharge temperature of the refrigerant is changed. Determine if the target value has been reached. Specifically, the control device 50 acquires the detection result of the temperature sensor 2a, and based on this detection result, the temperature of the refrigerant discharged from the compressor 1 is a predetermined second threshold value T2 (for example, 100). Determine if the temperature has been reached.

While the processes of steps S102 and S103 are repeated, 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, it may be difficult for the discharge temperature of the refrigerant to rise with time. Therefore, in step S103, when the increase in the discharge temperature of the refrigerant at a fixed time interval (for example, 5 seconds) does not reach a predetermined third threshold value (for example, 10 ° C.), the operating frequency of the compressor 1 is set. You may control to increase it. 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 period of 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 flow path switching valve 8 from the second bypass flow path B2 to the first bypass flow path B1.

FIG. 6 is a diagram showing the flow of the refrigerant in the second stage (S104, S105) at the time of defrosting 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 flow path 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 depressurized by the second expansion valve 6b and is sucked into the compressor 1 again.

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

Returning to FIG. 2 again, the control device 50 determines in step S105 whether or not the defrosting is completed. Specifically, in the control device 50, 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. Judge whether 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 that the defrosting of the second heat exchanger 7 is continued, and proceeds to step S104. Return the process. 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 that the defrosting of the second heat exchanger 7 is completed. Then, the process proceeds to step S106.

In step S106, the control device 50 sets the solenoid valve 3a in the open state and the solenoid valve 3b in 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 selection device 20 selects the second bypass flow path B2 and deselects the first bypass flow path B1 and the first heat exchanger 5 (FIG. 5, S102, S103), then the first bypass flow path B1 is selected, and the second bypass flow path B2 and the first heat exchanger 5 are not selected (FIGS. 6, S104, S105).

Next, the effect obtained by the air conditioner 100 according to the first embodiment will be described.
When the detection result of the temperature sensor 2b is equal to or lower than the predetermined threshold value and the second heat exchanger 7 is determined to have frosted, the control device 50 determines that the solenoid valve 3a, the solenoid valve 3b, and the flow path are formed. The switching valve 8 is operated to flow the entire amount of the refrigerant to the second bypass flow path B2. Next, when the detection result of the temperature sensor 2a reaches the preset second threshold value or more, the control device 50 operates the flow path switching valve 8 and operates the flow path switching valve 8 to pass through the first bypass flow path B1 to the second heat exchanger. The entire amount of the refrigerant is passed through No. 7 to defrost the second heat exchanger 7.

By flowing the refrigerant through the second bypass flow path B2, the temperature of the refrigerant rises in the loop shown by the solid line arrow in FIG. 5, so that the discharge temperature of the refrigerant can be made higher than in the 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 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 the comparative example in which the general defrosting that reverses the flow of the refrigerant in the cooling operation direction is performed. FIG. 8 is a ph diagram showing the state of the refrigerant during the defrosting operation according to the first embodiment. Compared to the general defrosting operation in which the flow of the refrigerant is reversed in the cooling operation direction shown in FIG. 7, the defrosting operation of the present embodiment shown in FIG. 8 has a high enthalpy and is in a more overheated gas region. It will be defrosting operation.

FIG. 9 is a diagram showing the temperature distribution of the refrigerant in the defrosting operation of the comparative example in the second heat exchanger 7 and the defrosting operation of the first embodiment in an overlapping manner. In the defrosting operation of the first embodiment shown in Ta'-Tb'in FIG. 9, the temperature difference between the refrigerant and the second heat exchanger 7 is larger than that in the defrosting operation of the comparative example shown in Ta-Tb of FIG. And the amount of heat exchange per unit time increases, so defrosting can be performed in a short time.

Further, the effect of raising the discharge temperature of the above-mentioned refrigerant and defrosting in a short time is that the types of refrigerants enclosed in the air conditioner, such as HFC refrigerants, HFO refrigerants, HC refrigerants, and non-co-boiling mixed refrigerants, can be used. It doesn't matter. Therefore, by using a refrigerant having a low GWP (Global Warming Potential) (for example, R290 (GWP3) which is one of the HC refrigerants), the total amount of GWP in the refrigeration cycle can be reduced.

Further, when the non-co-boiling mixed refrigerant is enclosed in the air conditioner, the inlet side of the refrigerant during heating of the outdoor heat exchanger is likely to be frosted, but in the present embodiment, the second heat is passed through the first bypass flow path B1. High-pressure and high-temperature refrigerant gas can flow to the heating inlet side of the exchanger 7, and the temperature difference between the refrigerant and the second heat exchanger 7 becomes large on the heating inlet side of the second heat exchanger 7 per unit time. The amount of heat exchange is increased. Therefore, defrosting can be performed in a short time.

In addition, compared to general defrosting that reverses the flow of the refrigerant in the cooling operation direction, defrosting in the gas region in a more superheated state increases the 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, as compared with general defrosting in which the flow of the refrigerant is reversed in the cooling operation direction, the refrigerant does not flow through the extension pipe 9a, the extension pipe 9b, and the first heat exchanger 5 in the room during the defrosting operation. The heat dissipation 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 the 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 less than the preset first threshold value, it is determined that the second heat exchanger 7 in the outdoor has frosted, and the defrosting operation is started, the solenoid valve 3a is started. Closed to eliminate the inflow of refrigerant in the main circuit 30, and at the same time, the solenoid valve 3b was opened to allow the entire amount of refrigerant to flow into the second bypass flow path B2, and then the flow path switching valve 8 was switched to open the first bypass flow path B1. Select and flush the entire amount of refrigerant 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 the difference in time from the determination of frost formation 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 the times t1 and t2 in order to create the pressure state required 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.

Further, when the detection result of the temperature sensor 2a becomes equal to or higher than the preset second threshold value, the defrosting of the outdoor second heat exchanger 7 is completed, and the heating operation is resumed, the solenoid valve 3b is closed and the solenoid valve 3a is closed. Open and change the flow of refrigerant from the first bypass flow path 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 the difference in time from the end of defrosting to the restoration of 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 the times t11 and t12 in order to create the pressure state required for switching the four-way valve 4. Therefore, as shown in FIG. 11, the time until the heating operation is restored 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.

With reference to FIG. 12 , the air conditioner 200 includes a main circuit 30, a first bypass flow path B1, a second bypass flow path B2, and a first flow path 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. Be prepared. Normally, 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 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, and the four-way valve in the main circuit 30. It circulates in the order of 4, and returns to the compressor 1.

The first bypass flow path B1 communicates the first expansion valve 6a side pipe (point P2) of the second heat exchanger 7 with the discharge side pipe (point P1) of the compressor 1.

The second bypass flow path B2 communicates the suction side pipe (point P4) of the compressor 1 with 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 by the compressor 1 to at least one of the first heat exchanger 5, the first bypass flow path B1, and the second bypass flow path B2. Will be done. In the second embodiment, the first flow path selection device 20A is configured to selectively pass the refrigerant discharged by the compressor 1 to 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 path selection device 20A selects the second bypass flow path B2 and does not select the first bypass flow path B1 and the first heat exchanger 5 (FIG. 2). 16) Then, the first bypass flow path B1 and the second bypass flow path B2 are selected, and the first heat exchanger 5 is not selected (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 path B2. In the heating operation, the third bypass flow path B3 is a flow path that branches from the pipe C1 through which the refrigerant that has passed through the second heat exchanger 7 flows to the suction side of the compressor 1. The third expansion valve 6d is arranged in the middle of the third bypass flow path B3. As the second flow path selection device, a flow path switching valve 8b for selectively connecting the pipe C2 or the third bypass flow path B3 can be used. The pipe C2 is a pipe that allows the pipe C1 to communicate with the suction side of the compressor 1 without passing through the third bypass flow path B3.

The air conditioner 200 of the second embodiment has the same basic configuration as the air conditioner 100 of the first embodiment, except for the following first to fourth points. First, the main circuit 30 has a flow path switching valve 8b, and the expansion valve 6b is removed. Second, the flow path switching valve 8 that selects the first bypass flow path B1 and the second bypass flow path B2 is replaced with the flow rate adjusting valve 10. Third, a second expansion valve 6c is provided in the second bypass flow path B2. Fourth, a third bypass flow path B3 having a third expansion valve 6d is provided. The flow rate adjusting valve 10 is configured so that the amount of the refrigerant to be distributed can be freely adjusted in the first bypass flow path B1 and the second bypass flow path B2. The flow rate adjusting valve 10 may have any configuration, and for example, an electronic expansion valve may be provided in each of the bidirectional branch paths through which the refrigerant flows.

In FIG. 12, the same components as those in the first embodiment are designated by the same reference numerals. Further, as in the first embodiment, fans for blowing air are provided on the outlet side or the inlet side of each of the air 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 plurality of fans may be 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. 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, which is the refrigerant outlet of the second heat exchanger 7, during the heating operation. The control device 50 includes a compressor 1, a four - way valve 4, a first expansion valve 6a, a flow path selection device 20A, a second expansion valve 6b, and an illustration based on the detection temperature of the temperature sensors 2a and 2b and a command from the user. Do not control the fan. Since the basic configuration of the control device 50 is the same as that of the first embodiment, the description will not be repeated.

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

Next, the operation of the air conditioner 200 according to the second embodiment of 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 the states of the elements in each process of the flowchart of FIG.

The defrosting operation executed in the second embodiment is the defrosting determination (S101) and the constant defrosting determination (S101) of the first embodiment in the defrosting determination (S201), the constant discharge temperature arrival determination (S203), and the defrosting end determination (S205). It is the same as the discharge temperature arrival determination (S103) and the defrosting end determination (S105). However, the second embodiment is different from the first embodiment in that the processing involving the operation of the valve (S200, S202, S204, S206, S207) and the determination of the certain stage progress of defrosting (S205) are performed.

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

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

With reference to FIGS. 13 and 14 again, in step S201, the control device 50 acquires information for determining whether or not the second heat exchanger 7 is frosted, and obtains information for determining whether or not the second heat exchanger 7 is frosted. It is determined whether or not 7 is frosted. Specifically, the control device 50 acquires the detection result of the temperature sensor 2b, and the surface temperature of the second heat exchanger 7 is set to a predetermined first threshold value (for example, -3) based on the detection result. ℃) It is judged whether or not it is less than or equal to. 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 once returned to the main routine, and the processes of S200 and S201 are repeated again. If 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 opens the solenoid valve 3a and 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 path 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 opens the expansion valve 6d fully.

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

Since the solenoid valve 3a is in the closed state and the expansion valve 6d is in the open state, a part of the refrigerant staying in the first heat exchanger 5 and the second heat exchanger 7 is sucked by the path indicated by the broken line arrow. It is taken out and heated in the loop indicated by the solid arrow.

In step S202, the first expansion valve 6a and the expansion valve 6d are fully opened. This is to promptly flow the refrigerant remaining in the main circuit 30 into the loop indicated by the solid arrow including the second bypass flow path B2 when switching to the defrosting operation. 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 in which the pressure difference becomes small before and after the second expansion valve 6c and the discharge pressure / discharge temperature of the refrigerant does not rise when the opening degree of the second expansion valve 6c is too large. Further, this is to prevent the amount of the refrigerant flowing into the suction side of the compressor 1 from becoming excessively small when the opening degree of the second expansion valve 6c is too small.

With reference to FIGS. 13 and 14 again, the control device 50 acquires information for determining whether or not the discharge temperature of the refrigerant has reached the target value in step S203, and the discharge temperature of the refrigerant is changed. Determine if the target value has been reached. Specifically, the control device 50 acquires the detection result of the temperature sensor 2a, and based on this detection result, the temperature of the refrigerant discharged from the compressor 1 is a predetermined second threshold value T2 (for example, 100). Determine if the temperature has been reached.

While the processes of steps S202 and S203 are repeated, 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, it may be difficult for the discharge temperature of the refrigerant to rise with time. Therefore, in step S203, when the increase in the discharge temperature of the refrigerant at a fixed time interval (for example, 5 seconds) does not reach a predetermined third threshold value (for example, 10 ° C.), the operating frequency of the compressor 1 is set. You may control to increase it. 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 period of 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 path 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 (S204, S205) at the time of defrosting 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 flow path B1 and is introduced into the second heat exchanger 7. The high temperature and high pressure refrigerant defrosts the second heat exchanger 7. Further, the refrigerant flowing out from the second heat exchanger 7 is depressurized by the third expansion valve 6d and is sucked into the compressor 1 again.

Next, the control device 50 determines in step S205 whether the defrosting has progressed to a certain stage. Specifically, in the control device 50, the surface temperature of the second heat exchanger 7 is set to a predetermined fourth threshold value (for example, −0.5 ° C.) based on the detection signal output from the temperature sensor 2b. It is determined whether or not the above is the case. 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 in a certain step.

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 flow path B1 and the second bypass flow path B2.

FIG. 18 is a diagram showing the flow of the refrigerant in the third stage (S206, S207) at the time of defrosting 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 flow path B1 and is introduced into the second heat exchanger 7, and the defrosting of the second heat exchanger 7 continues. Will be done. Further, the refrigerant flowing out of the second heat exchanger 7 is depressurized by the third expansion valve 6d and is sucked into the compressor 1 again. Further, a part of the refrigerant discharged from the compressor 1 passes through the second bypass flow path B2, is depressurized by the second expansion valve 6c, and is sucked into the compressor 1 again.

Next, in step S207, the control device 50 determines whether or not the defrosting is completed. Specifically, in the control device 50, is the surface temperature of the second heat exchanger 7 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? Judge whether or not. The control device 50 determines that the defrosting of the second heat exchanger 7 is completed when the surface temperature of the second heat exchanger 7 is equal to or higher than the third threshold value.

When it is determined that the defrosting is completed (YES in S207), the control device 50 sets the solenoid valve 3a in the open state and the solenoid valve 3b in the closed state in step S208, and selects the flow path switching valve 8b for the third step. The bypass flow path B3 is switched to the pipe C2. As a result, as shown in FIG. 15, a steady heating operation in which the refrigerant flows is performed.

Although the defrosting time is slightly longer, the processes of steps S204 and S205 may be omitted. Further, the process of step S204 and the process of step S206 may be exchanged.

Next, the effect 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 is started to be distributed to the second bypass flow path B2 just before the end of defrosting in the second embodiment. The suction temperature Ts of the compressor 1 starts to rise according to the amount of the refrigerant distributed at this time. FIG. 20 is a ph diagram showing the state of the refrigerant at a time when a certain time has elapsed after the start of distribution of the refrigerant to the second bypass flow path B2 in the second embodiment. As the suction temperature Ts'rises after a certain period of time, the discharge temperature Td' also rises. This makes it possible to return to the heating operation in a state where 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 restoration 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 at time t23 from the end of defrosting at time t22, the four-way valve is switched, 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 path B1 and the second bypass flow path B2 at time t32 when the defrosting of the second heat exchanger 7 has progressed in a certain step by the end of defrosting. It is possible to raise the discharge temperature of the refrigerant while continuing the defrosting. Therefore, even after the determination of the end of defrosting is determined at time t33, the discharge temperature of the refrigerant does not decrease, 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 is high at the end of the defrosting operation, in the second embodiment, the time from the start of defrosting to the return to heating is from ΔT3 as compared with the conventional case. It is shortened to ΔT4, and a quick warming effect can be obtained when the heating operation is restored.

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

With reference to FIG. 23, the air conditioner 300 includes a main circuit 30, a first bypass flow path B1, a second bypass flow path B2, and a first flow path 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. Be prepared. Normally, 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 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, and the four-way valve in the main circuit 30. It circulates in the order of 4, and returns to the compressor 1.

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

The second bypass flow path B2 communicates the suction side pipe of the compressor 1 with the discharge side pipe of the compressor 1 via the first flow path selection device 20B.

The air conditioner 300 further includes a second expansion valve 6e. The second expansion valve 6e is provided in the middle of the second bypass flow path B2 in FIG. 23.

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

The air conditioner 300 is a third flow path selection device 20C configured to connect the first bypass flow path B1 and the first expansion valve 6a to either the first heat exchange section 7a or the second heat exchange section 7b. Further prepare.

The third 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 portion 7a. The solenoid valve 3d opens and closes the flow path connecting the first expansion valve 6a and the second heat exchange portion 7b. The solenoid valve 3e opens and closes the flow path connecting the first bypass flow path B1 and the first heat exchange portion 7a. The solenoid valve 3f opens and closes the flow path connecting the first bypass flow path B1 and the second heat exchange portion 7b.

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

Specifically, in the third embodiment, the first flow path selection device 20B distributes and flows the refrigerant to the main circuit 30 and the second bypass flow path B2 during the defrosting operation (FIGS. 27 and 31). Next, the refrigerant flows through either the first heat exchange unit 7a or the second heat exchange unit 7b through the main circuit 30, and either the first heat exchange unit 7a or the second heat exchange unit 7b passes through the first bypass flow path B1. Refrigerant is flowed to one or the other (FIGS. 28 and 32).

In the third flow path selection device 20C, during the defrosting operation, the first bypass flow path B1 is connected to either the first heat exchange section 7a or the second heat exchange section 7b, and the first expansion valve 6a is connected to the first expansion valve 6a. 1 Connects to either the heat exchange unit 7a or the second heat exchange unit 7b (FIGS. 28 and 32).

The air conditioner 300 of the third embodiment has the same basic configuration as that of the first embodiment, but has a flow control valve 10b in the main circuit 30, a point that the expansion valve 6b is removed, an electromagnetic valve 3c, and an electromagnetic wave. A point having a valve 3d, a point having a first heat exchange part 7a and a second heat exchange part 7b in which the second heat exchanger 7 is divided, and a point provided in the first heat exchange part 7a and the second heat exchange part 7b, respectively. The point having the temperature sensors 2c and 2d, the point having the expansion valves 6f and 6g provided corresponding to the first heat exchange part 7a and the second heat exchange part 7b, and the electromagnetic wave at the outlet of the first bypass flow path B1. The difference is that the valve 3e and the electromagnetic valve 3f are provided, and the expansion valve 6e is provided in the middle of the second bypass flow path B2. The same components as those in the first embodiment are designated by the same reference numerals.

Further, fans for blowing air are provided on the outlet side or the inlet side of the air of the second heat exchanger 7 and the first heat exchanger 5, respectively (not shown). As each fan, any of a line flow fan, a propeller fan, a turbo fan, a sirocco fan and the like may be used. Further, a plurality of fans may be used for one heat exchanger. Further, the first heat exchange unit 7a and the second heat exchange unit 7b may be arranged so as to be arranged in the horizontal direction or arranged in the vertical direction. Further, the above 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 provided in the first heat exchange unit 7a and the temperature sensor 2d provided in the second heat exchange unit 7b are provided at positions (point P10 side) on the outlet side of the refrigerant during the heating operation. Has been done.

As in the first embodiment, the type of the refrigerant enclosed in the air conditioner is not limited. As the refrigerant, an HFC refrigerant, an HFO refrigerant, an HC refrigerant, a non-azeotropic mixed refrigerant, or the like may be sealed.

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 the states of the elements in each process of the flowchart of FIG. 24. In FIG. 25, the open / closed states of the solenoid valves 3c, 3d, 3b, 3e, and 3f in each process of FIG. 24, the flow direction of the refrigerant in the flow path switching valve 8, and the distribution state of the refrigerant in the flow rate adjusting valve 10b are shown. It is shown.

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

The controls described with reference to FIGS. 24 and 25 are controls for defrosting the first heat exchange unit 7a from the heating operation, and later, FIGS. 29 to 29 for defrosting the second heat exchange unit 7b. This will be described with reference to FIG.

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

FIG. 26 is a diagram showing the flow of the refrigerant during heating (S300, S301, S306) of 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, and the four-way valve 4 are discharged. It circulates in the order of, and 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, and merge at point P10.

With reference to FIGS. 24 and 25 again, in step S301, the control device 50 acquires information for determining whether or not the first heat exchange unit 7a is frosted, and obtains information for determining whether or not the first heat exchange unit 7a is frosted. It is determined whether or not 7a is frosted. Specifically, the control device 50 acquires the detection result of the temperature sensor 2c, and the surface temperature of the first heat exchange unit 7a is set to a predetermined first threshold value (for example, −) based on the detection result. 3 ° C) or less is determined. The control device 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. If it is determined that frost has formed, the control device 50 proceeds with the process in step S302. If it is determined that the frost has not formed, the processes of steps S302 to S306 are not executed, and the processes of steps S300 and S301 are repeated again.

In step S302, in the control device 50, the solenoid valve 3c is in the closed state and the solenoid valve 3b is in the open state, the flow path switching valve 8 selects the second bypass flow path B2, and the flow control valve 10 uses the refrigerant as the main circuit 30. Each valve is controlled so as to be distributed to the pipe C0 of the above and the second bypass flow path 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 the flow of the refrigerant in the first stage (S302, S303) during the defrosting operation of the first heat exchange unit 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 unit 7b to continue the heating operation, and the other part of the refrigerant flows to the second bypass flow. It passes through the passage B2, is depressurized by the expansion valve 6e, and is sucked into the compressor 1 again.

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

Subsequently, in step S303, the control device 50 acquires information for determining whether or not the discharge temperature of the refrigerant has reached the target value, and whether or not the discharge temperature of the refrigerant has reached the target value. Is determined. Specifically, the control device 50 acquires the detection result of the temperature sensor 2a, and based on this detection result, the temperature of the refrigerant discharged from the compressor 1 is a predetermined second threshold value T2 (for example, 100). ℃) is determined. When the discharge temperature of the refrigerant reaches the second threshold value T2 in step S303, the control device 50 proceeds to the process in step S304.

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, it may be difficult for the discharge temperature of the refrigerant to rise with time. Therefore, in step S303, when the increase in the discharge temperature of the refrigerant at a fixed time interval (for example, every 5 seconds) does not reach a predetermined third threshold value (for example, 10 ° C.), the operating frequency of the compressor 1 You may control to increase the frequency. Alternatively, the temperature of the refrigerant discharged from the compressor 1 even after a certain period of time (for example, 60 seconds) has elapsed from the time when the process of step S302 is started has a predetermined second threshold value (for example, 100 ° C.). If it is less than the above, 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 flow path switching valve 8 selects the first bypass flow path 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 unit 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 flow path B1 and is introduced into the first heat exchange section 7a. In this way, the first heat exchange section 7a is defrosted. Further, the refrigerant flowing out from the first heat exchange unit 7a is depressurized by the expansion valve 6f.

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 the fully open position. 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 merge at the point P10.

Next, in step S305, the control device 50 determines whether or not the defrosting is completed. Specifically, in the control device 50, is the surface temperature of the first heat exchange unit 7a 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? Judge whether or not. The control device 50 determines that the defrosting is completed when the surface temperature of the first heat exchange unit 7a is equal to or higher than the third threshold value. If it is determined that the defrosting is completed, the control device 50 proceeds to the process in step S306.

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

Next, the operation of defrosting the second heat exchange unit 7b will be described.
FIG. 29 is a flowchart for explaining the operation of each element during the defrosting operation of the second heat exchange unit 7b in the third embodiment. FIG. 30 is a diagram showing states of elements in each process of the flowchart of FIG. 29. 30 shows 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. 29, the flow direction of the refrigerant in the flow path switching valve 8, and the refrigerant in the flow rate adjusting valve 10b. The distribution status is shown.

In the flowchart of FIG. 29, steps S301 to S305 are replaced with steps S301A to S305A in the flowchart of FIG. 24.

When the heating operation is started, in step S300, the control device 50 has the solenoid valve 3c in the open state, the solenoid valve 3d in the open state, the solenoid valve 3b in the closed state, the solenoid valve 3e in the closed state, and the solenoid valve 3f in the closed state. The flow path switching valve 8 selects the first bypass flow path B1, and the flow control valve 10b controls these valves so that the entire amount of the refrigerant flows to 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 whether or not the second heat exchange unit 7b is frosted. Is determined. Specifically, the control device 50 acquires the detection result of the temperature sensor 2d, and the surface temperature of the second heat exchange unit 7b is set to a predetermined first threshold value (for example,-) based on the detection result. 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 solenoid valve 3d is in the closed state and the solenoid valve 3b is in the open state, the flow path switching valve 8 selects the second bypass flow path B2, and the flow control valve 10 uses the refrigerant as the main circuit 30. Each valve is controlled so as to be distributed to the pipe C0 of the above and the second bypass flow path 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 the flow of the refrigerant in the first stage (S302A, S303A) during the defrosting operation of the second heat exchange unit 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 unit 7a to continue the heating operation, and the other part of the refrigerant flows to the second bypass flow. It passes through the passage B2, is depressurized by the expansion valve 6e, and is sucked into the compressor 1 again.

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

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 whether or not the discharge temperature of the refrigerant has reached the target value. Is determined. Specifically, the control device 50 acquires the detection result of the temperature sensor 2a, and the temperature of the refrigerant discharged from the compressor 1 is set to a predetermined second threshold value (for example, 100 ° C.) based on the detection result. ) Has been reached. When the discharge temperature of the refrigerant reaches the second threshold value in step S303A, the control device 50 proceeds to the process in step S304A.

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, it may be difficult for the discharge temperature of the refrigerant to rise with time. Therefore, in step S303A, when the increase in the discharge temperature of the refrigerant at a constant time interval (for example, every 5 seconds) does not reach a predetermined third threshold value (for example, 10 ° C.), the operating frequency of the compressor 1 is increased. You may control it. 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 period of time (for example, 60 seconds) has elapsed from the time when the process of step S302A is started. If it does not meet the requirements, 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 flow path switching valve 8 selects the first bypass flow path B1. The state of step S302A is maintained for the solenoid valves 3b, 3c, 3d, 3e and the flow rate adjusting valve 10b.

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 unit 7b. As shown in FIG. 32, a part of the high-temperature and high-pressure refrigerant discharged from the compressor 1 flows through the first bypass flow path B1 and is introduced into the second heat exchange section 7b. In this way, the second heat exchange section 7b is defrosted. Further, the refrigerant flowing out from the second heat exchange section 7b is depressurized by the expansion valve 6g.

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 expansion 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 merge at the point P10.

Next, the control device 50 determines in step S305A whether or not the defrosting is completed. Specifically, in the control device 50, is the surface temperature of the second heat exchange unit 7b 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? Judge whether or not. The control device 50 determines that the defrosting is completed when the surface temperature of the second heat exchange unit 7b is equal to or higher than the third threshold value. If it is determined that the defrosting is completed, the control device 50 proceeds to the process in step S306.

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

As described above, in the third embodiment, when only one of the first heat exchange unit 7a and the second heat exchange unit 7b is frosted by the processing of the flowcharts shown in FIGS. 24 and 29, the heat exchange of the frosted one is performed. Defrost the part. However, if the two heat exchange units are frosted at the same time, defrosting is performed with the following priority.

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

FIG. 33 is a flowchart for explaining an example of the process of defrosting the first heat exchange unit 7a in preference to the second heat exchange unit 7b in the third embodiment. The numbers of the steps are the same as those of the steps of FIGS. 24 and 29, and the detailed description is not repeated.

With reference to FIG. 33, first, in step S300, the control device 50 flows a refrigerant in parallel with the first heat exchange unit 7a and the second heat exchange unit 7b, and performs a normal heating operation. Then, the control device 50 determines in step S301 whether or not the first heat exchange unit 7a is frosted.

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 heating using the second heat exchange unit 7b with a part of the refrigerant, and remains. The refrigerant of the above is flowed through the second bypass flow path B2 and circulated to raise the temperature of the refrigerant.

After that, in steps S304 and S305, the control device 50 continues heating using the second heat exchange section 7b with a part of the refrigerant, and the remaining refrigerant is passed through the first bypass flow path B1 to the first heat exchange section. The first heat exchange section 7a is defrosted by flowing it through 7a.

If it is determined in step S301 that there is no frost formation, or if the processes of steps S304 and S305 are executed and the defrosting of the first heat exchange unit 7a is completed, then in step S301A, the control device 50 receives the second heat. It is determined whether or not the replacement unit 7b is frosted.

When it is determined in step S301A that there is frost formation (YES in S301A), in steps S302A and S303A, the control device 50 continues heating using the first heat exchange unit 7a with a part of the refrigerant, and remains. The refrigerant of the above is flowed through the second bypass flow path B2 and circulated to raise the temperature of the refrigerant.

After that, in steps S304A and S305A, the control device 50 continues heating using the first heat exchange unit 7a with a part of the refrigerant, and the remaining refrigerant is used as the second heat exchange unit via the first bypass flow path B1. The second heat exchange section 7b is defrosted by flowing it through 7b.

If it is determined in step S301A that there is no frost formation, or if the processes of steps S304A and S305A are executed and the defrosting of the second heat exchange unit 7b is completed, the process of step S306 is subsequently advanced. In step S306, the control device 50 changes the setting of each valve so that the refrigerant flows in parallel with the first heat exchange unit 7a and the second heat exchange unit 7b so as to perform the normal heating operation, and performs the process. Return to the main routine.

Next, the effect of the air conditioner according to the third embodiment of 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 path B2 to flow the refrigerant, and then distributed to the main circuit 30 and the first bypass flow path B1 to flow the refrigerant. The heating operation can be continued even during the defrosting operation.

Further, 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 the comfort is improved.

Finally, the effects of the air conditioner according to the first to third embodiments will be summarized.
The air conditioner of the present disclosure includes a first bypass flow path B1 connecting the discharge side of the compressor 1 and the heating inlet side of the outdoor second heat exchanger 7, the discharge side of the compressor 1 and the suction side of the compressor 1. A second bypass flow path B2 is provided. The control device 50 operates the flow path selection devices 20, 20A, 20B when the temperature of the outdoor second heat exchanger 7 becomes equal to or lower than a predetermined first threshold value, and bypasses the refrigerant to the second bypass. The refrigerant flows through the flow path B2, and then the refrigerant flows through the first bypass flow path B1 to the outdoor second heat exchanger 7 to defrost.

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

Further, by increasing the discharge temperature of the refrigerant, when the flow path selection devices 20, 20A, 20B are switched to the first bypass flow path B1, the outdoor first outdoor position is in a state where the temperature of the refrigerant is higher than that during normal heating operation. 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 usual, the temperature difference between the refrigerant and the frosted heat exchanger becomes large in the entire area of the second heat exchanger 7 outdoors, and per unit time. Since the amount of heat exchange is increased, defrosting can be performed in a short time.

Further, the above-mentioned effect of raising the discharge temperature of the refrigerant and defrosting in a short time can be obtained regardless of the type of refrigerant enclosed in the air conditioner, such as HFC refrigerant, HFO refrigerant, HC refrigerant, and non-co-boiling mixed refrigerant. However, in particular, by using a refrigerant having a low GWP (for example, R290 (GWP3) which is one of the HC refrigerants), the total amount of GWP in the cycle can be reduced.

Further, when the non-azeotropic mixed refrigerant is enclosed in the air conditioner, frost is likely to be formed on the refrigerant inlet side during heating of the outdoor heat exchanger. On the other hand, in the air conditioner of the present embodiment, high-pressure and high-temperature refrigerant gas can flow to the heating refrigerant inlet side of the second heat exchanger 7 through the first bypass flow path B1. For this reason, the temperature difference between the refrigerant and the frosted heat exchanger on the heating refrigerant inlet side of the second heat exchanger 7 becomes large, and the amount of heat exchange per unit time increases, so that 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 superheated state, as compared with defrosting by switching to a general cooling operation. Therefore, the degree of superheat (SH) of the suction refrigerant of the compressor 1 becomes large, and the liquid back to the compressor 1 is less likely to occur, so that the reliability of the compressor 1 can be improved.

Further, in the air conditioner of the present embodiment, as compared with the defrosting operation by switching to the general cooling operation, the refrigerant uses the extension pipes 9a and 9b and the first heat exchanger 5 in the room during the defrosting operation. Since it does not pass through, heat dissipation loss can be reduced.

Further, 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 defrosting operation by switching the general cooling operation. No heat is absorbed by the heat exchanger 5, and it is possible to reduce the decrease in room temperature during the defrosting operation.

Further, in the air conditioner of the present embodiment, when the defrosting operation is started, the flow path selection devices 20, 20A, 20B are operated to eliminate the inflow of the refrigerant into the main circuit 30, and the refrigerant is used as the second bypass flow path B2. Then, the refrigerant is flowed 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 eliminates the need to stop the compressor to create the pressure state required for switching the four-way valve, thus shortening the time to start defrosting. Can be done.

Further, when the defrosting operation is completed and the heating operation is restored, the flow path selection devices 20, 20A, 20B are operated to flow the entire amount of the refrigerant to the main circuit 30, so that the four-way valve is switched when the heating operation is restored. do not have. For this reason, it is not necessary to stop the compressor to create the pressure state required for switching the four-way valve, so the time to return to the heating operation is shorter than the defrosting operation by switching to the general cooling operation. can do.

The embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Compressor, 2a, 2b, 2c, 2d Temperature sensor, 3a, 3b, 3c, 3d, 3e, 3f Electromagnetic valve, 4 Four-way valve, 5 First heat exchanger, 6a, 6b, 6c, 6d, 6e, 6f , 6g expansion valve, 7 second heat exchanger, 7a first heat exchange section, 7b second heat exchange section, 8 switching valve, 8b, 20, 20A, 20B, 20C selection device, 9a, 9b extension pipe, 10, 10b Flow control valve, 30 main circuit, 50 controller, 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 (10)

During the heating operation, the main circuit in which the refrigerant circulates in the order of the compressor, the four- way valve, the first heat exchanger, the first expansion valve, the second heat exchanger, the four-way valve, and the compressor .
A first bypass flow path that communicates the first expansion valve side pipe of the second heat exchanger and the discharge side pipe of the compressor.
A second bypass flow path that communicates 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 to at least one of the first heat exchanger, the first bypass flow path, and the second bypass flow path. And with
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 with the first heat exchanger not selected. death,
The four-way valve is an air conditioner having the same communication state during the heating operation and the defrosting operation . During the defrosting operation, the first flow path selection 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. The air conditioner according to claim 1, wherein the 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 path or between the second bypass flow path and the suction side pipe of the compressor. .. The first flow path selection device is
A first solenoid valve provided in a pipeline between the discharge side of the compressor and the first heat exchanger,
On the discharge side of the compressor, a second solenoid valve provided in a branch pipe from the main circuit , which is shared by the first bypass flow path and the second bypass flow path,
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 the first bypass flow path or the second bypass flow path. During the defrosting operation, the first flow path selection 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. The air conditioner according to claim 1, wherein the path and the second bypass flow path are selected and the first heat exchanger is not selected. A second expansion valve arranged 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, and
A third expansion valve arranged in the middle of the third bypass flow path,
Further equipped with a second flow path selection device,
The second flow path selection device selectively connects the second pipe or the third bypass flow path that connects the first pipe to the suction side of the compressor without passing through the third bypass flow path. , The air conditioner according to claim 1 or 5. The second heat exchanger is
Including the first heat exchange section and the second heat exchange section
During the defrosting operation, the first flow path selection 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 section through the main circuit. The air conditioner according to claim 1, wherein the refrigerant flows through the first bypass flow path to the second heat exchange unit. A third flow path selection device configured to connect the first bypass flow path and the first expansion valve to either the first heat exchange section or the second heat exchange section is further provided.
During the defrosting operation, the third flow path selection device connects the first bypass flow path to either the first heat exchange section or 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 either the first heat exchange unit or the second heat exchange unit. 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.

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