Air conditioning system

Abstract

To provide an air conditioning system that enables high-speed defrosting while maintaining heating functionality and can be made compact. [Solution] The air conditioning system comprises a compressor having a discharge section and a suction section; an indoor heat exchanger having a first refrigerant inlet and a second

Description

Technical Field

[0001] The present invention relates to an air conditioner.

Background Art

[0002] When heating operation is performed by a heat pump type air conditioner, when frosting occurs on the outdoor heat exchanger, defrosting may be performed by switching from the heating cycle to the cooling cycle. However, in this defrosting method, even if the indoor fan is stopped, cold air is gradually released from the indoor unit, so there is a drawback that the heating feeling is lost.

[0003] Therefore, there is a refrigeration cycle device that provides two outdoor heat exchangers and one indoor heat exchanger and performs simultaneous heating and defrosting operation (for example, Patent Document 1). The simultaneous heating and defrosting operation includes a first operation and a second operation. During the first operation, the first outdoor heat exchanger and the indoor heat exchanger function as condensers, and the second outdoor heat exchanger functions as an evaporator. Thereby, defrosting of the first outdoor heat exchanger is performed and heating is continued. During the second operation, the second outdoor heat exchanger and the indoor heat exchanger function as condensers, and the first outdoor heat exchanger functions as an evaporator. Thereby, defrosting of the second outdoor heat exchanger is performed and heating is continued.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the refrigeration cycle device described in Patent Document 1, since the first operation and the second operation cannot be performed simultaneously, defrosting of the first outdoor heat exchanger and defrosting of the second outdoor heat exchanger are performed alternately, and the defrosting time becomes long.

[0006] Therefore, the present invention aims to provide an air conditioning system that can achieve high-speed defrosting while maintaining heating functionality. [Means for solving the problem]

[0007] An air conditioning system according to one aspect of the present invention comprises: a compressor having a discharge section and a suction section; an indoor heat exchanger having a first refrigerant inlet and a second

[0008] According to this embodiment, the discharge section that discharges gaseous refrigerant is connected to the first refrigerant inlet / outlet and the third refrigerant inlet / outlet, allowing high-pressure gaseous refrigerant to be supplied to the first and third refrigerant inlet / outlet. This enables simultaneous defrosting of the entire outdoor heat exchanger and heating operation. Therefore, an air conditioning system can be provided that can suppress the time required for defrosting. Furthermore, in this embodiment, where a pressure reduction section is provided between the discharge section and the third refrigerant inlet / outlet, for example, when the gaseous refrigerant discharged from the discharge section is circulated to both the indoor and outdoor heat exchangers, it is possible to suppress excessive refrigerant flow to the outdoor heat exchanger. This suppresses a decrease in the heating capacity of the indoor heat exchanger, thus maintaining a good indoor environment. In addition, by supplying refrigerant to the outdoor heat exchanger from the third refrigerant inlet / outlet, which facilitates the flow of large-volume gaseous refrigerant, a decrease in flow rate can be suppressed, thus suppressing the time required for defrosting. Therefore, an air conditioning system can be provided that enables high-speed defrosting while maintaining heating function.

[0009] In the above embodiment, the air conditioning system may further include: a first pipe having one end and the other end connected to the second refrigerant inlet and outlet; a second pipe having one end and the other end connected to the suction section; an auxiliary heat exchanger for exchanging heat between the refrigerant flowing through the first pipe and the second pipe, respectively; a third pipe connecting the other end of the first pipe to the fourth refrigerant inlet and outlet; a fourth pipe connecting the other end of the second pipe to the third pipe; an expansion valve provided in the third pipe; and a two-way valve provided in the fourth pipe.

[0010] Thus, by providing an auxiliary heat exchanger, for example, heat contained in the refrigerant flowing from the indoor heat exchanger to the first piping can be transferred to the refrigerant flowing from the fourth piping to the second piping. Since the indoor heat exchanger is a stable heat source, the supply of heat to the refrigerant flowing through the second piping can be stabilized and the evaporation of the refrigerant can be promoted without providing a large heat storage tank in terms of size or mass.

[0011] In the above embodiment, the fourth pipe may connect the other end of the second pipe to the space between the expansion valve and the fourth refrigerant inlet / outlet in the third pipe.

[0012] In this configuration, connecting the fourth pipe between the expansion valve and the fourth refrigerant inlet / outlet makes it easier to control the refrigerant flow rate on the indoor unit side with the expansion valve, thereby suppressing a decrease in the discharge temperature.

[0013] In the above embodiment, when switching from heating operation to heating defrosting operation, the opening of the two-way valve may occur before or simultaneously with the switching operation of the first switching valve.

[0014] According to this embodiment, when switching from heating operation to heating defrosting operation, pressure fluctuations of the refrigerant in the refrigerant circuit can be suppressed.

[0015] In the above embodiment, when switching from heating defrosting operation to heating operation, the switching operation of the first switching valve may be performed before or simultaneously with the closing operation of the two-way valve.

[0016] According to this embodiment, when switching from heating and defrosting operation to heating operation, pressure fluctuations of the refrigerant in the refrigerant circuit can be suppressed.

[0017] In the above embodiment, the air conditioning system may further include a pressure reducer provided in the fourth piping.

[0018] According to this embodiment, the refrigerant pressure on the auxiliary heat exchanger side of the pressure reducer can be lowered, thereby lowering the refrigerant temperature and increasing the temperature difference between the refrigerant flowing through the first pipe and the refrigerant flowing through the second pipe. This increases the heat transfer from the refrigerant flowing through the first pipe to the refrigerant flowing through the second pipe, thus promoting the evaporation of the refrigerant flowing through the second pipe. Furthermore, the pressure drop of the refrigerant on the fourth refrigerant inlet / outlet side of the pressure reducer due to the compressor's suction can be suppressed, thus suppressing the temperature drop on the fourth refrigerant inlet / outlet side of the outdoor heat exchanger. This effectively prevents a decrease in the defrosting capacity of the outdoor heat exchanger and an increase in the time required for defrosting.

[0019] In the above embodiment, the first switching valve connects the third refrigerant inlet / outlet to the pressure reducing section during heating and defrosting operation, the second switching valve connects the first refrigerant inlet / outlet to the discharge section during heating and defrosting operation, and the two-way valve may be open during heating and defrosting operation.

[0020] According to this embodiment, the refrigerant can be circulated so that the air conditioning system operates as a defrosting and heating system.

[0021] In the above embodiment, the temperature of the refrigerant in the first piping may be higher than the temperature of the refrigerant in the second piping.

[0022] According to this embodiment, heat can be transferred from the refrigerant flowing through the first pipe to the refrigerant flowing through the second pipe, thereby promoting the evaporation of the refrigerant flowing through the second pipe.

[0023] In the above aspect, during the heating operation, the first switching valve connects the third refrigerant inlet / outlet to the suction part, and during the heating operation, the second switching valve connects the first refrigerant inlet / outlet to the discharge part. The two-way valve may be closed during the heating operation.

[0024] According to this aspect, the refrigerant can be circulated so that the air conditioner operates as a heating device.

[0025] In the above aspect, during the cooling operation, the first switching valve connects the third refrigerant inlet / outlet to the decompression part, and during the heating operation, the second switching valve connects the first refrigerant inlet / outlet to the suction part. The two-way valve may be closed during the cooling operation.

[0026] According to this aspect, the refrigerant can be circulated so that the air conditioner operates as a cooling device.

Advantages of the Invention

[0027] According to the present invention, it is possible to provide an air conditioner capable of realizing high-speed defrosting while maintaining the heating function.

Brief Description of the Drawings

[0028] [Figure 1] It is a diagram showing an overview of the heating defrosting operation of the air conditioner 201 according to the present embodiment. [Figure 2] It is a diagram showing an overview of the heating operation of the air conditioner 201 according to the present embodiment. [Figure 3] It is a diagram showing an overview of the cooling operation of the air conditioner 201 according to the present embodiment. [Figure 4] It is a side view of the auxiliary heat exchanger 301 according to the present embodiment. [Figure 5] It is a cross-sectional view of the auxiliary heat exchanger 301 according to the present embodiment. [Figure 6] It is a side view of the auxiliary heat exchanger 302 which is a modified example of the auxiliary heat exchanger 301. [Figure 7] This is a side view of the auxiliary heat exchanger 301 with a different connection configuration than the auxiliary heat exchanger 301 shown in Figure 4. [Figure 8] Figure 7 is a cross-sectional view of the auxiliary heat exchanger 301. [Modes for carrying out the invention]

[0029] The embodiments of the present invention will be described below in detail with reference to the drawings. The embodiments described below are merely examples of how to implement the present invention and are not intended to limit the scope of the invention. Furthermore, to facilitate understanding of the explanation, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations may be omitted.

[0030] [During heating and defrosting operation, defrosting is performed while maintaining heating.] Figure 1 is a diagram showing an overview of the heating and defrosting operation of the air conditioning system 201 according to this embodiment. As shown in Figure 1, the air conditioning system 201 comprises an indoor unit 1 and an outdoor unit 2. The indoor unit 1 includes an indoor heat exchanger 13. The indoor heat exchanger 13 has a first refrigerant inlet / outlet 51 and a second refrigerant inlet / outlet 52.

[0031] The outdoor unit 2 includes a compressor 11, a branch pipe 16, expansion valves 14 and 18 (examples of "two-way valves" and "pressure reducers"), an outdoor heat exchanger 15, an accumulator 17, a pressure reducing section 21, four-way valves 31 (example of "first switching valve") and 41 (example of "second switching valve"), piping 63 (example of "third piping"), 64 (example of "fourth piping"), 65 and 66, a check valve 71, and an auxiliary heat exchanger 301. The outdoor heat exchanger 15 has a third refrigerant inlet / outlet 53 and a fourth refrigerant inlet / outlet 54.

[0032] The following describes the refrigerant circuit 10, but the explanation of the piping connecting the components may be omitted.

[0033] During heating and defrosting operation, the refrigerant circulates in the refrigerant circuit 10 in the following order: compressor 11, four-way valve 41, indoor heat exchanger 13, auxiliary heat exchanger 301, expansion valve 14, expansion valve 18, auxiliary heat exchanger 301, accumulator 17 and compressor 11, as well as in the following order: compressor 11, pressure reducing two-way valve 21, four-way valve 31, outdoor heat exchanger 15, expansion valve 18, auxiliary heat exchanger 301, accumulator 17 and compressor 11.

[0034] The compressor 11 has a refrigerant discharge section 11a and a refrigerant intake section 11b. The compressor 11 draws in low-temperature, low-pressure gaseous refrigerant through the refrigerant intake section 11b, compresses the drawn-in refrigerant, generates high-temperature, high-pressure gaseous refrigerant, and discharges it from the refrigerant discharge section 11a.

[0035] The branching section 81 distributes the refrigerant discharged from the refrigerant discharge section 11a to the pressure reducing two-way valve 21 and the four-way valve 41. Specifically, the branching section 81 connects the refrigerant discharge section 11a, the pressure reducing two-way valve 21, and the four-way valve 41. The branching section 82 connects the pressure reducing two-way valve 21, the check valve 71, and the four-way valve 31.

[0036] The check valve 71 has one end and the other end, with the flow from one end to the other being in the forward direction. More specifically, the check valve 71 has one end connected to the four-way valve 41 and the other end connected to the branch section 82. The refrigerant flows from the four-way valve 41 through the check valve 71 to the branch section 82. On the other hand, the refrigerant does not flow from the branch section 82 through the check valve 71 to the four-way valve 41.

[0037] The pressure reducing section 21 is provided between the refrigerant discharge section 11a and the other end of the check valve 71, and is composed of, for example, a two-way valve. When the pressure reducing section 21 is composed of a two-way valve, it also has a pressure reducing function, and is therefore sometimes referred to as the "pressure reducing two-way valve 21" in the following description.

[0038] The pressure reducing two-way valve 21 has one end connected to the refrigerant discharge section 11a through the branch section 81, and the other end connected to the third refrigerant inlet / outlet 53.

[0039] The pressure reducing two-way valve 21 limits the flow rate of refrigerant from branch 81 to branch 82 (and consequently, the amount of refrigerant distributed to the outdoor heat exchanger). When the refrigerant passes through the pressure reducing two-way valve 21, the refrigerant pressure decreases. At branch 82, the refrigerant is in a gaseous state.

[0040] It is preferable to use the pressure reducing two-way valve 21 in an open state at all times. In this case, there is no need to separately control the opening and closing of the pressure reducing two-way valve 21 between each operation, which simplifies the control process.

[0041] The pressure reducing two-way valve 21 may be closed during heating and cooling operations. In this case, the pressure reducing two-way valve 21 is composed of, for example, a solenoid valve.

[0042] The pressure reducing two-way valve 21 may be composed of a two-way valve with an adjustable opening degree. In this case, the amount of refrigerant distributed to the outdoor heat exchanger 15 can be adjusted by adjusting the opening degree of the pressure reducing two-way valve 21.

[0043] The pressure reducing section 21 may be composed of piping with an inner diameter smaller than the inner diameter of the pipeline between branch sections 81 and 82, instead of a two-way valve. In this case, the configuration of the device can be further simplified and costs can be reduced. The pressure reducing section 21 may also be composed of other components that reduce the pressure of the refrigerant flowing to the outdoor heat exchanger 15, and may be provided at a location other than between branch sections 81 and 82.

[0044] The four-way valve 31 connects the third refrigerant inlet / outlet 53 to either the branching section 82 or the refrigerant suction section 11b. The four-way valve 31 can be selectively switched between a first connection state, in which the branching section 82 and the third refrigerant inlet / outlet 53 are connected, and a second connection state, in which the refrigerant suction section 11b and the third refrigerant inlet / outlet 53 are connected. The four-way valve 31 is switched to the first connection state during heating and defrosting operation.

[0045] In this embodiment, since only three of the four ports of the four-way valve 31 are used, it may be composed of a three-way valve. More specifically, the four-way valve 31 has a first port connected to the pressure reducing two-way valve 21 through the branch section 82, a second port connected to the third refrigerant inlet / outlet 53, a third port connected to the branch pipe 16, and a closed fourth port.

[0046] During heating and defrosting operation, the four-way valve 31 connects the first and second ports, and also connects the third and fourth ports.

[0047] The four-way valve 41 connects the first refrigerant inlet / outlet 51 to either the refrigerant discharge section 11a or the refrigerant suction section 11b. In this embodiment, the four-way valve 41 can be selectively switched between a first connection state in which the refrigerant discharge section 11a and the refrigerant suction section 11b are connected to the first refrigerant inlet / outlet 51 and one end of the check valve 71, respectively, and a second connection state in which the refrigerant discharge section 11a and the refrigerant suction section 11b are connected to one end of the check valve 71 and the first refrigerant inlet / outlet 51, respectively. The four-way valve 41 is switched to the first connection state during heating and defrosting operation.

[0048] In this embodiment, the four-way valve 41 has a first port connected to the refrigerant discharge section 11a through the branch section 81, a second port connected to the first refrigerant inlet / outlet 51, a third port connected to the branch pipe 16, and a fourth port connected to one end of the check valve 71.

[0049] The four-way valve 41 connects the first port and the second port, and also connects the third port and the fourth port, during heating and defrosting operation.

[0050] The branch pipe 16 connects the refrigerant intake section 11b with the four-way valve 31 and the four-way valve 41. More specifically, the branch pipe 16 has a first port connected to the refrigerant intake section 11b through a part of the piping 65 and the accumulator 17, a second port connected to the third port of the four-way valve 31, and a third port connected to the third port of the four-way valve 41.

[0051] During heating and defrosting operation, the second port of the branch pipe 16 is connected to the fourth port of the closed four-way valve 31. The third port of the branch pipe 16 is connected to one end of the check valve 71 through the four-way valve 41, but the third port of the branch pipe 16 and the branch section 82 are not in communication due to the check valve 71. Therefore, no refrigerant flows through the branch pipe 16.

[0052] The indoor heat exchanger 13 includes a gas header 13a, a heat exchange section 13b, a distributor 13c, and a fan 13d.

[0053] The gas header 13a includes a first refrigerant inlet / outlet 51. The gas header 13a distributes high-pressure gaseous refrigerant supplied from the compressor 11 through a branch section 81, a four-way valve 41, and the first refrigerant inlet / outlet 51 to a plurality of branch pipes.

[0054] The heat exchange section 13b includes, for example, a plurality of heat transfer tubes connected to a plurality of branch tubes in the gas header 13a. Fins, for example, are connected to the plurality of heat transfer tubes.

[0055] During heating and defrosting operation, the fan 13d rotates to draw indoor air into the indoor unit 1 and discharges the air that has passed through the heat exchange section 13b to the outside of the indoor unit 1, i.e., into the room.

[0056] In the heat exchange tubes of the heat exchange section 13b, heat exchange takes place between the refrigerant supplied from the gas header 13a and the indoor air. As a result, the air heated by the heat exchange section 13b is blown into the room from the indoor unit 1. Also, inside the heat exchange tubes of the heat exchange section 13b, the temperature of the refrigerant decreases due to heat exchange, and it undergoes a phase change from a gaseous state to a liquid state.

[0057] The distributor 13c includes a second refrigerant inlet / outlet 52 and a plurality of flow rate adjustment throttles connected to a plurality of heat transfer tubes in the heat exchange section 13b. The distributor 13c, for example, combines the liquid refrigerant flowing in from the heat exchange section 13b through the plurality of throttles and supplies it to the auxiliary heat exchanger 301 through the second refrigerant inlet / outlet 52 and piping 66.

[0058] The outdoor heat exchanger 15 includes a gas header 15a, a heat exchange section 15b, a distributor 15c, and a fan 15d.

[0059] The gas header 15a includes a third refrigerant inlet / outlet 53. The gas header 15a distributes high-pressure gaseous refrigerant supplied from the compressor 11 to multiple branch pipes through a pressure reducing two-way valve 21, a branch section 82, a four-way valve 31, and the third refrigerant inlet / outlet 53.

[0060] The heat exchange section 15b includes, for example, a plurality of heat transfer tubes connected to a plurality of branch tubes in the gas header 15a. Fins, for example, are connected to the plurality of heat transfer tubes.

[0061] Fan 15d is stopped during heating and defrosting operation. In the heat exchange section 15b, heat exchange takes place between the refrigerant in the heat transfer tubes and the frost adhering to the heat transfer tubes and fins. As a result, the frost is heated and turns into liquid water, which is then removed from the heat exchange section 15b. Also, inside the heat transfer tubes in the heat exchange section 15b, the refrigerant's temperature decreases due to heat exchange, and it undergoes a phase change from a gaseous state to a liquid state.

[0062] The distributor 15c includes a fourth refrigerant inlet / outlet 54 and a plurality of flow rate regulating throttles connected to a plurality of heat transfer tubes in the heat exchange section 15b. The distributor 15c, for example, combines the liquid refrigerant flowing in from the heat exchange section 15b through the plurality of throttles and supplies it to the piping 63 through the fourth refrigerant inlet / outlet 54.

[0063] The auxiliary heat exchanger 301 includes piping 61 (an example of "first piping") and 62 (an example of "second piping"). Piping 61 has one end connected to the second refrigerant inlet / outlet 52 through piping 66 and the other end on the expansion valve 14 side. Piping 62 has one end connected to the refrigerant suction section 11b through piping 65 and the accumulator 17 and the other end on the expansion valve 18 side. The auxiliary heat exchanger 301 causes heat exchange between the refrigerants flowing through piping 61 and 62, respectively.

[0064] Piping 63 connects the other end of piping 61 to the fourth refrigerant inlet / outlet 54. The expansion valve 14 is provided in piping 63.

[0065] In detail, piping 63 includes piping 63a and 63b. Piping 63b has one end connected to the other end of piping 61 and the other end connected to one end of the expansion valve 14. Piping 63a has one end connected to the fourth refrigerant inlet / outlet 54 and the other end connected to the other end of the expansion valve 14.

[0066] Pipe 64 connects the other end of pipe 62 to pipe 63. In this embodiment, pipe 64 connects the other end of pipe 62 to the space between the expansion valve 14 and the fourth refrigerant inlet / outlet 54 in pipe 63. That is, pipe 64 connects the other end of pipe 62 to pipe 63a.

[0067] The expansion valve 14 is slightly restricted during heating and defrosting operation. This limits the flow rate of refrigerant from piping 63b to piping 63a. As the refrigerant passes through the expansion valve 14, the refrigerant pressure decreases. In piping 63a, the refrigerant is in a liquid state.

[0068] The expansion valve 18 is installed in the piping 64. The expansion valve 18 is opened slightly during heating and defrosting operation.

[0069] When the refrigerant passes through the expansion valve 18, the pressure of the refrigerant decreases. At this time, some of the refrigerant may gasify.

[0070] In the auxiliary heat exchanger 301, the temperature of the refrigerant in piping 61 is higher than the temperature of the refrigerant in piping 62.

[0071] The refrigerant supplied from the expansion valve 18 to the piping 62 is heated by heat exchange with the refrigerant flowing through the piping 61. As a result, the refrigerant undergoes a phase change, mostly from a liquid state to a gaseous state.

[0072] In other words, during heating and defrosting operation, the auxiliary heat exchanger 301 functions as an evaporator. This makes it easier for high-temperature refrigerant to flow to the outdoor heat exchanger 15, thereby shortening the time required for defrosting the outdoor heat exchanger 15.

[0073] The refrigerant is drawn from the piping 62 to the refrigerant intake 11b of the compressor 11 through the accumulator 17 by the negative pressure of the compressor 11. At this time, even if a portion of the refrigerant is in a liquid state, this portion is accumulated in the accumulator 17, so that gaseous refrigerant is drawn into the refrigerant intake 11b of the compressor 11. This suppresses the return of liquid to the compressor 11, thereby reducing the load on the compressor 11 and preventing malfunction or damage.

[0074] [During heating operation] Figure 2 is a diagram showing an overview of the air conditioning system 101 according to this embodiment during heating operation. As shown in Figure 2, during heating operation, the refrigerant circulates in the refrigerant circuit 10 in the following order: compressor 11, branch section 81, four-way valve 41, indoor heat exchanger 13, auxiliary heat exchanger 301, expansion valve 14, outdoor heat exchanger 15, four-way valve 31, branch pipe 16, accumulator 17, and compressor 11.

[0075] The pressure reducing two-way valve 21 is closed during heating operation. The four-way valve 31 connects the third refrigerant inlet / outlet 53 to the refrigerant suction section 11b during heating operation.

[0076] In detail, the four-way valve 31 connects the first and fourth ports, and also connects the second and third ports, during heating operation. As a result, the third refrigerant inlet / outlet 53 is connected to the refrigerant suction section 11b through the four-way valve 31 and the branch pipe 16.

[0077] During heating operation, the four-way valve 31 connects the branch pipe 16 and the outdoor heat exchanger 15, so no refrigerant flows through the pipeline from the branch section 81 to the four-way valve 31 (and consequently, through the pressure reducing two-way valve 21). Therefore, during heating operation, the pressure reducing two-way valve 21 may be open or closed.

[0078] During heating operation, the four-way valve 41 connects the first refrigerant inlet / outlet 51 to the refrigerant discharge section 11a. In this embodiment, during heating operation, the four-way valve 41 switches to a first connection state in which the refrigerant discharge section 11a and the refrigerant suction section 11b are connected to the first refrigerant inlet / outlet 51 and one end of the check valve 71, respectively.

[0079] In detail, the four-way valve 41 connects the first and second ports, and also connects the third and fourth ports, during heating operation.

[0080] During heating operation, the refrigerant intake section 11b is connected to one end of the check valve 71 via the branch pipe 16. Since the direction from the branch section 82 to the four-way valve 41 is opposite to the direction of the check valve 71, the refrigerant does not flow from the check valve 71 to the third port of the branch pipe 16. In other words, no refrigerant flows through the third port of the branch pipe 16.

[0081] The gas header 13a in the indoor heat exchanger 13 distributes the high-pressure gaseous refrigerant supplied from the compressor 11 through the branch section 81, the four-way valve 41, and the first refrigerant inlet / outlet 51 to multiple branch pipes.

[0082] During heating operation, the fan 13d rotates to draw indoor air into the indoor unit 1 and discharges the air that has passed through the heat exchange section 13b to the outside of the indoor unit 1, i.e., into the room.

[0083] In the heat exchange tubes of the heat exchange section 13b, heat exchange takes place between the refrigerant supplied from the gas header 13a and the indoor air. As a result, the air heated by the heat exchange section 13b is blown into the room from the indoor unit 1. Also, inside the heat exchange tubes of the heat exchange section 13b, the temperature of the refrigerant decreases due to heat exchange, and it undergoes a phase change from a gaseous state to a liquid state.

[0084] The distributor 13c combines the liquid refrigerant supplied from the heat exchange unit 13b through multiple throttling sections, for example, and supplies it to the auxiliary heat exchanger 301 through the second refrigerant inlet / outlet 52 and piping 66.

[0085] The expansion valve 14 is slightly restricted during heating operation. As a result, when the refrigerant supplied from the auxiliary heat exchanger 301 passes through the expansion valve 14, the refrigerant pressure decreases and the refrigerant temperature decreases. In piping 63a, the refrigerant is in a two-phase state, consisting of a gaseous state and a liquid state.

[0086] The expansion valve 18 closes during heating operation. As a result, refrigerant does not flow through parts of the piping 64, 62, and 65, and therefore almost no heat exchange occurs in the auxiliary heat exchanger 301.

[0087] In the outdoor heat exchanger 15, the distributor 15c distributes the refrigerant supplied from the piping 63a through the fourth refrigerant inlet / outlet 54 to multiple throttle sections. In each of the multiple throttle sections, the liquid volume of the refrigerant is equalized, and the refrigerant is supplied to each heat transfer tube in the heat exchange section 15b.

[0088] During heating operation, the fan 15d rotates to draw in outside air into the outdoor unit 2 and discharges the air that has passed through the heat exchange section 15b to the outside of the outdoor unit 2.

[0089] In the heat exchange tubes of the heat exchange section 15b, heat exchange takes place between the refrigerant supplied from the distributor 15c and the outdoor air. Inside the heat exchange tubes of the heat exchange section 15b, the refrigerant undergoes a phase change from a two-phase state of gaseous and liquid states to a gaseous state due to heat exchange. The air cooled by the heat exchange section 15b is then blown outside from the outdoor unit 2.

[0090] The gas header 15a brings together the gaseous refrigerant supplied from multiple heat transfer tubes in the heat exchange section 15b via branch pipes.

[0091] The refrigerant is drawn in by the negative pressure of the compressor 11 from the third refrigerant inlet / outlet 53 through the four-way valve 31, the branch pipe 16, and the accumulator 17 to the refrigerant suction section 11b of the compressor 11.

[0092] When switching from heating operation to heating defrosting operation, the opening of the expansion valve 18 occurs before or simultaneously with the switching operation of the four-way valve 31. On the other hand, when switching from heating defrosting operation to heating operation, the switching operation of the four-way valve 31 occurs before or simultaneously with the closing operation of the expansion valve 18.

[0093] [During cooling operation] Figure 3 is a diagram showing an overview of the air conditioning system 101 according to this embodiment during cooling operation. As shown in Figure 3, during cooling operation, the refrigerant circulates in the refrigerant circuit 10 in the following order: compressor 11, four-way valve 41, check valve 71, four-way valve 31, outdoor heat exchanger 15, expansion valve 14, auxiliary heat exchanger 301, indoor heat exchanger 13, four-way valve 41, branch pipe 16, accumulator 17, and compressor 11.

[0094] It is preferable that the pressure reducing two-way valve 21 be closed during cooling operation. The four-way valve 31 connects the third refrigerant inlet / outlet 53 to the other end of the check valve 71 during cooling operation. However, since the pressure reducing two-way valve 21 performs a pressure reducing function, it may be opened during cooling operation if it does not significantly affect the flow of refrigerant through the check valve 71.

[0095] In detail, the four-way valve 31 connects the first and second ports, and also connects the third and fourth ports, during cooling operation.

[0096] During cooling operation, when the pressure reducing two-way valve 21 is closed, no refrigerant flows through the pressure reducing two-way valve 21. Also, during cooling operation, the second port of the branch pipe 16 is connected to the fourth port of the closed four-way valve 31, so no refrigerant flows through the second port of the branch pipe 16.

[0097] During cooling operation, the four-way valve 41 switches to a second connection state in which the refrigerant discharge section 11a and the refrigerant suction section 11b are connected to one end of the check valve 71 and the first refrigerant inlet / outlet 51, respectively.

[0098] In detail, the four-way valve 41 connects the first port and the fourth port, and also connects the second port and the third port, during cooling operation.

[0099] During cooling operation, the refrigerant discharge section 11a is connected to one end of the check valve 71 through the four-way valve 41. Since the direction from the four-way valve 41 to the branch section 82 is the forward direction of the check valve 71, the refrigerant is supplied from the refrigerant discharge section 11a to the third refrigerant inlet / outlet 53 through the four-way valve 41, the check valve 71, and the four-way valve 31.

[0100] The gas header 15a in the outdoor heat exchanger 15 distributes the high-pressure gaseous refrigerant supplied from the compressor 11 through a four-way valve 41, a check valve 71, a four-way valve 31, and a third refrigerant inlet / outlet 53 to multiple branch pipes.

[0101] During cooling operation, the fan 15d rotates to draw in outside air into the outdoor unit 2 and discharges the air that has passed through the heat exchange section 15b to the outside of the outdoor unit 2.

[0102] In the heat exchange tubes of the heat exchange section 15b, heat exchange takes place between the refrigerant supplied from the gas header 15a and the outdoor air. Inside the heat exchange tubes of the heat exchange section 15b, the temperature of the refrigerant decreases due to the heat exchange, and it undergoes a phase change from a gaseous state to a liquid state. The air heated by the heat exchange section 15b is then blown outside from the outdoor unit 2.

[0103] The distributor 15c combines the refrigerant supplied from the heat exchange unit 15b through multiple throttling sections and supplies it to the piping 63a.

[0104] The expansion valve 18 closes during cooling operation. As a result, refrigerant does not flow through parts of the piping 64, 62, and 65, and therefore almost no heat exchange occurs in the auxiliary heat exchanger 301.

[0105] The expansion valve 14 is slightly restricted during cooling operation. As a result, when the refrigerant supplied from piping 63a passes through the expansion valve 14, the refrigerant pressure decreases and the refrigerant temperature decreases. In piping 63b, 61, and 66, the refrigerant is in a two-phase state, consisting of a gaseous state and a liquid state.

[0106] In the indoor heat exchanger 13, the distributor 13c distributes the refrigerant supplied from the piping 66 through the second refrigerant inlet / outlet 52 to multiple throttle sections. In each of the multiple throttle sections, the liquid volume of the refrigerant is equalized, and the refrigerant is supplied to each heat transfer tube in the heat exchange section 13b.

[0107] During cooling operation, the fan 13d rotates to draw indoor air into the indoor unit 1 and discharges the air that has passed through the heat exchange section 13b to the outside of the indoor unit 1, i.e., into the room.

[0108] In the heat exchange tubes of the heat exchange section 13b, heat exchange takes place between the refrigerant supplied from the distributor 13c and the indoor air. As a result, the air cooled by the heat exchange section 13b is blown into the room from the indoor unit 1. Inside the heat exchange tubes of the heat exchange section 13b, the refrigerant undergoes a phase change from a two-phase state of gaseous and liquid states to a gaseous state due to heat exchange.

[0109] The gas header 13a brings together the gaseous refrigerant supplied from multiple heat transfer tubes in the heat exchange section 13b via branch pipes.

[0110] The refrigerant is drawn in by the negative pressure of the compressor 11 from the first refrigerant inlet / outlet 51 through the four-way valve 41, the branch pipe 16, and the accumulator 17 to the refrigerant suction section 11b of the compressor 11.

[0111] As described above, the heating and cooling operations can be switched by switching the connection state of the four-way valves 31 and 41. Specifically, during heating operation, the four-way valve 31 is in the second connection state and the four-way valve 41 is in the first connection state. During cooling operation, the four-way valve 31 is in the first connection state and the four-way valve 41 is in the second connection state.

[0112] During heating operation, switching the four-way valve 31 to the first connection state switches from heating operation to heating defrosting operation. The connection state of the four-way valve 31 during heating defrosting operation is the same as the connection state of the four-way valve 31 during cooling operation.

[0113] [Structure of auxiliary heat exchanger 301] The structure of the auxiliary heat exchanger 301 will be described below. Each drawing may show the X, Y, and Z axes. The X, Y, and Z axes form a three-dimensional Cartesian coordinate system in a right-handed system. Hereinafter, the direction of the arrow on the X axis may be called the X-axis+ side, and the direction opposite to the arrow may be called the X-axis- side, and the same applies to the other axes. The Z-axis+ side and Z-axis- side may also be called the "upper side" and "lower side," respectively. Furthermore, the planes perpendicular to the X, Y, or Z axes may be called the YZ plane, ZX plane, or XY plane, respectively.

[0114] Figure 4 is a side view of the auxiliary heat exchanger 301 according to this embodiment. Figure 5 is a cross-sectional view of the auxiliary heat exchanger 301 according to this embodiment.

[0115] As shown in Figures 4 and 5, the piping 61 (an example of the "first cylindrical section") in the auxiliary heat exchanger 301 (an example of the "auxiliary evaporator") extends along the X-axis direction (an example of the "first direction"). The piping 61 has a cylindrical shape. In this embodiment, the piping 61 has a cylindrical shape. However, the piping 61 may also have a rectangular cylindrical shape.

[0116] The piping 61 has a cylindrical internal space 161 (an example of the "first internal space") that extends along the X-axis.

[0117] The internal space 161 is through which the refrigerant supplied from the refrigerant discharge section 11a through the indoor heat exchanger 13 and piping 66 flows. In this embodiment, the refrigerant flows in the internal space 161 in the direction of the X-axis+.

[0118] The pipe 61 is formed of, for example, metal. In this embodiment, the pipe 61 is formed of a metal containing copper, which has good thermal conductivity. However, the pipe 61 may be formed of other types of metal or resin.

[0119] Furthermore, pipe 61 has the same inner diameter as pipe 66, which is connected to the indoor heat exchanger 13. Also, pipe 61 has the same inner diameter as pipe 63b. In other words, the inner circumferential surfaces of each pipe, including pipe 66, pipe 61, and pipe 63b, are smooth.

[0120] Specifically, pipes 63b and 66 may have, for example, a cylindrical shape. Pipe 61 may have the outer diameter of pipe 63b and pipe 66. For example, it may be formed by a single pipe spanning pipe 66, pipe 61 and pipe 63b.

[0121] The pipe 62 (an example of the "second cylindrical section") extends along the X-axis direction. The pipe 62 has a cylindrical shape. In this embodiment, the pipe 62 has a cylindrical shape. However, the pipe 62 may also have a rectangular cylindrical shape.

[0122] The piping 62 is an internal space 162 (an example of a "second internal space") that extends along the X-axis direction and has a cylindrical internal space 162 through which the piping 61 passes.

[0123] The pipe 62 is formed of, for example, metal. In this embodiment, the pipe 62 is formed of a metal containing copper. However, the pipe 62 may be formed of other types of metal or of resin.

[0124] In the central part of pipe 62, the inner surface of pipe 62 and the outer surface of pipe 61 (an example of an "outer surface") do not come into contact. As a result, a space (hereinafter sometimes referred to as the flow space 162a) is formed between the inner surface of pipe 62 and the outer surface of pipe 61.

[0125] On the other hand, the diameter of both ends of pipe 62 is narrowed so that the inner surface of pipe 62 is in contact with the outer surface of pipe 61. In other words, the outer diameter and inner diameter at both ends of pipe 62 are smaller than the outer diameter and inner diameter at the center.

[0126] At both ends of pipe 62, the inner surface of pipe 62 and the outer surface of pipe 61 are, for example, brazed. As a result, both ends of pipe 62 are sealed, and the flow space 162a becomes a closed space.

[0127] The piping 64 (an example of the "fourth cylindrical section") extends along the Z-axis direction (an example of the "second direction"). The piping 64 has, for example, a cylindrical shape. The piping 64 penetrates the lower outer peripheral surface of the outer peripheral surface of the piping 62 and is brazed to the piping 62. This connects the internal space of the piping 64 with the flow space 162a, forming a refrigerant inlet.

[0128] The pipe 65 (an example of the "third cylindrical section") extends along the Z-axis direction. The pipe 65 has, for example, a cylindrical shape. The pipe 65 is provided on the X-axis side of the pipe 64. The pipe 65 penetrates the upper outer peripheral surface of the outer peripheral surface of the pipe 62 and is brazed to the pipe 62. This connects the internal space of the pipe 65 with the flow space 162a, forming a refrigerant outlet.

[0129] The pipes 62, 64, and 65 may be formed, for example, by joining two T-joints.

[0130] When the expansion valve 18 is open, that is, when heating and defrosting operation is being performed, refrigerant flowing upward through the piping 64 is supplied to the flow space 162a.

[0131] The refrigerant flowing from piping 64 into the flow space 162a flows in the direction of the X axis. That is, the direction of refrigerant flow in the internal space 161 and the direction of refrigerant flow in the flow space 162a are opposite to each other. However, these directions of flow may be the same.

[0132] Heat exchange occurs between the refrigerant circulating in the internal space 161 and the refrigerant circulating in the circulation space 162a through the metal constituting the piping 61. When heating and defrosting operation is performed, the refrigerant circulating in the circulation space 162a is heated by receiving heat from the high-temperature refrigerant circulating in the internal space 161.

[0133] The refrigerant heated in the flow space 162a is discharged upward from the flow space 162a through the piping 65.

[0134] [Variations in the structure] Figure 6 is a side view of an auxiliary heat exchanger 302, which is a modified example of the auxiliary heat exchanger 301. As shown in Figure 6, the auxiliary heat exchanger 302 further includes an electric heater 311 (an example of a "heating section") compared to the auxiliary heat exchanger 301.

[0135] The electric heater 311 is, for example, a linear sheath heater. The electric heater 311 is in contact with the outer surface of the pipe 62. More specifically, the electric heater 311 is wrapped around the outer surface of the pipe 62, spirally covering the outer surface of the pipe 62. The electric heater 311 may also be a heater of other shapes, such as a strip-shaped sheet heater.

[0136] The electric heater 311 is secured, for example, by a band. The electric heater 311 is covered with an insulating material (not shown), for example, glass cloth. This helps to suppress the amount of heat escaping from the auxiliary heat exchanger 301 to the outside.

[0137] In this configuration, by supplying heat to the refrigerant circulating in the circulation space 162a from both the refrigerant circulating inside the circulation space 162a and the electric heater 311 provided outside the circulation space 162a, the refrigerant in the circulation space 162a can be heated efficiently.

[0138] Although the description has shown the pipe 64 extending along the Z-axis, it is not limited to this configuration. The pipe 64 may extend along any direction, such as the Y-axis, as long as it intersects with the X-axis.

[0139] Furthermore, while we have described a configuration in which the piping 65 extends along the Z-axis direction, it is not limited to this configuration. The piping 65 may extend along any direction, such as the Y-axis direction, as long as it intersects with the X-axis direction.

[0140] [Variations of connection methods] Figure 7 is a side view of an auxiliary heat exchanger 301 with a different connection configuration than the auxiliary heat exchanger 301 shown in Figure 4. Figure 8 is a cross-sectional view of the auxiliary heat exchanger 301 shown in Figure 7.

[0141] As shown in Figures 7 and 8, in this modified example, pipes 63b and 66 penetrate the outer surface of pipe 62, instead of pipes 64 and 65, compared to the outer surface of pipe 62 shown in Figures 4 and 5.

[0142] Furthermore, in this modified example, pipes 65 and 64 are connected to both ends of pipe 61, instead of pipes 66 and 63b, as shown in Figures 4 and 5.

[0143] Refrigerant supplied from the refrigerant discharge section 11a of the compressor 11 through the indoor heat exchanger 13 flows through the circulation space 162a.

[0144] The refrigerant that has flowed through the flow space 162a and the refrigerant supplied from the refrigerant discharge section 11a through the outdoor heat exchanger 15 flow through the expansion valve 18 and the internal space 161 and are drawn into the refrigerant intake section 11b of the compressor 11.

[0145] The temperature of the refrigerant circulating in the circulation space 162a is higher than the temperature of the refrigerant circulating in the internal space 161.

[0146] In this embodiment, a configuration in which an expansion valve 18 is provided in the piping 64 has been described, but the invention is not limited to this configuration. The piping 64 may be configured to have a two-way valve instead of an expansion valve 18. Preferably, the piping 64 may be configured to have a pressure reducing device in addition to the two-way valve. The two-way valve and the pressure reducing device may be separate components, or the two functions may be combined into a single pressure reducing two-way valve.

[0147] Furthermore, although this embodiment describes a configuration in which a four-way valve 31 is provided, the system is not limited to this configuration. Instead of the four-way valve 31, a three-way valve may be provided that connects the third refrigerant inlet / outlet 53 to either the refrigerant discharge section 11a or the refrigerant suction section 11b.

[0148] Furthermore, although this embodiment describes a configuration in which a four-way valve 41 is provided, the system is not limited to this configuration. Instead of the four-way valve 41, a three-way valve may be provided that connects the first refrigerant inlet / outlet 51 to either the refrigerant discharge section 11a or the refrigerant suction section 11b.

[0149] Furthermore, although this embodiment describes a configuration in which pipe 64 connects the other end of pipe 62 to pipe 63a, it is not limited to this configuration. Pipe 64 may also be configured to connect the other end of pipe 62 to pipe 63b, i.e., between the auxiliary heat exchanger 301 and the expansion valve 14 in pipe 63.

[0150] In addition, in this embodiment, a throttle valve (not shown) may be provided between the connection point of pipe 64 and pipe 63 and the fourth refrigerant inlet / outlet 54 of the outdoor heat exchanger 15.

[0151] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The elements, arrangement, materials, conditions, shapes, and sizes of the embodiments are not limited to those exemplified and can be modified as appropriate. Furthermore, it is possible to partially substitute or combine the configurations shown in different embodiments. [Explanation of Symbols]

[0152] 1…Indoor unit 2…Outdoor unit 10…Refrigerant circuit 11… Compressor 11a...refrigerant discharge part 11b... Refrigerant intake 13…Indoor heat exchanger 13a... Gas header 13b...Heat exchange section 13c…Distributor 13d...fan 14…Expansion valve 15...Outdoor heat exchanger 15a...Gas header 15b...Heat exchange section 15c…Distributor 15d...fan 16... Branch pipe 17... Accumulator 18…Expansion valve 21... Pressure Reducing Two-Way Valve 31, 41... Four-way valve 51...First refrigerant inlet / outlet 52...Second refrigerant inlet / outlet 53...Third refrigerant inlet / outlet 54…Fourth refrigerant inlet / outlet 61, 62, 63, 63a, 63b, 64, 65, 66… Piping 71... Check valve 81, 82... Branching point 201... Air conditioning system 161, 162... Interior space 162a…Distribution space 301, 302…Auxiliary heat exchanger 311… Electric heater

Claims

1. A compressor having a discharge section and a suction section, An indoor heat exchanger having a first refrigerant inlet and a second refrigerant inlet and a second refrigerant inlet and a An outdoor heat exchanger having a third refrigerant inlet and a fourth refrigerant inlet and a A pressure reducing section is provided between the discharge section and the third refrigerant inlet / outlet, A first switching valve that connects the third refrigerant inlet / outlet to either the pressure reducing section or the suction section, The system includes a second switching valve that connects the first refrigerant inlet / outlet to either the discharge section or the suction section, Air conditioning system.

2. The aforementioned air conditioning system, An auxiliary heat exchanger comprising a first pipe having one end and the other end connected to the second refrigerant inlet and outlet, and a second pipe having one end and the other end connected to the suction section, which exchanges heat between the refrigerant flowing through the first pipe and the second pipe, respectively, A third pipe connecting the other end of the first pipe to the fourth refrigerant inlet / outlet, A fourth pipe connecting the other end of the second pipe to the third pipe, An expansion valve provided in the third pipe, The fourth pipe further comprises a two-way valve, The air conditioning device according to claim 1.

3. The fourth pipe connects the other end of the second pipe to the expansion valve and the fourth refrigerant inlet / outlet in the third pipe. The air conditioning device according to claim 2.

4. When switching from heating operation to heating defrost operation, The opening operation of the two-way valve is performed before or simultaneously with the switching operation of the first switching valve. The air conditioning device according to claim 2.

5. When switching from heating / defrosting operation to heating operation, The switching operation of the first switching valve is performed before or simultaneously with the closing operation of the two-way valve. The air conditioning device according to claim 2.

6. The aforementioned air conditioning system, The third pipe further comprises a pressure reducer, The air conditioning device according to claim 2.

7. The first switching valve, during heating and defrosting operation, connects the third refrigerant inlet / outlet to the pressure reducing section. The second switching valve, during the heating and defrosting operation, connects the first refrigerant inlet / outlet to the discharge section. The two-way valve opens during the heating and defrosting operation. The air conditioning device according to claim 2.

8. The temperature of the refrigerant in the first pipe is higher than the temperature of the refrigerant in the second pipe. The air conditioning device according to claim 7.

9. The first switching valve, during heating operation, connects the third refrigerant inlet / outlet to the suction section. The second switching valve, during the heating operation, connects the first refrigerant inlet / outlet to the discharge section. The two-way valve closes during the heating operation. The air conditioning device according to claim 2.

10. The first switching valve, during cooling operation, connects the third refrigerant inlet / outlet to the pressure reducing section. The second switching valve, during the cooling operation, connects the first refrigerant inlet / outlet to the suction section. The two-way valve closes during the cooling operation. The air conditioning device according to claim 2.

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