An air conditioning system

Abstract

The present invention discloses an air-conditioning system, which switches the state of the condenser or evaporator of the outdoor heat exchanger through a first reversing valve, and switches the state of the condenser or evaporator of the indoor heat exchanger through a second reversing valve. When defrosting is required during heating of the air-conditioning system, the second reversing valve remains unchanged to maintain the heating mode of the indoor heat exchanger unchanged, and controls the reversal of the first reversing valve to switch the outdoor heat exchanger from the evaporator to the condenser for defrosting. The refrigerant condensed from the outdoor heat exchanger and the indoor heat exchanger is mixed in the supercooler, and the relatively high-temperature refrigerant causes the relatively low-temperature refrigerant to vaporize, and returns to the suction side of the compressor after passing through the gas-liquid separator, thereby avoiding the problem of the traditional switching of the air-conditioning system to a refrigeration refrigerant circuit causing the indoor ambient temperature to drop, and achieving a good defrosting effect without affecting the user's comfort experience.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to an air conditioning system capable of defrosting an outdoor heat exchanger without changing a heating mode. Background Art

[0002] When the air conditioner is operating in heating mode, if the outdoor temperature is too low, frost will form on the outdoor heat exchanger, and the outdoor heat exchanger needs to be defrosted in a timely manner.

[0003] Traditional air conditioner outdoor heat exchanger defrosting usually uses a reversing valve to switch to a refrigeration refrigerant circuit, converting the indoor heat exchanger into an evaporator and the outdoor heat exchanger into a condenser. The heat dissipated by the condenser is used to melt the frost on the surface of the outdoor heat exchanger.

[0004] However, this defrosting method will cause the indoor heat exchanger to absorb heat from the room as it is converted into an evaporator, causing the indoor ambient temperature to drop, giving users an uncomfortable experience. Summary of the Invention

[0005] The object of the present invention is to propose an air-conditioning system, which switches the state of the outdoor heat exchanger to the condenser or evaporator through a first reversing valve, and switches the state of the indoor heat exchanger to the condenser or evaporator through a second reversing valve. When defrosting is required during heating of the air-conditioning system, the second reversing valve remains unchanged to maintain the heating mode of the indoor heat exchanger unchanged, and controls the reversal of the first reversing valve to switch the outdoor heat exchanger from the evaporator to the condenser for defrosting, thereby avoiding the problem of the traditional switching of the air-conditioning system to a refrigeration refrigerant circuit causing the indoor ambient temperature to drop, and the defrosting effect is good without affecting the user's comfort experience.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] An air conditioning system is proposed, comprising:

[0008] An outdoor unit and an indoor unit; wherein the outdoor unit includes an outdoor heat exchanger (3), and the indoor unit includes an indoor heat exchanger (4);

[0009] A first reversing valve (1) is arranged in the outdoor unit and is used to switch the state of the outdoor heat exchanger (3) between the condenser and the evaporator;

[0010] A second reversing valve (2) is arranged in the outdoor unit and is used to switch the state of the indoor heat exchanger (4) between the condenser and the evaporator;

[0011] The controller is configured as:

[0012] When the air conditioning system operates in a heating mode, the first reversing valve (1) and the second reversing valve (2) are controlled so that the outdoor heat exchanger (3) is used as an evaporator and the indoor heat exchanger (4) is used as a condenser;

[0013] When the air-conditioning system is running in the heating mode and needs to be defrosted, the second reversing valve (2) is maintained and the first reversing valve (1) is controlled to be reversed, so that the indoor heat exchanger (4) is maintained as a condenser to perform heating, and the outdoor heat exchanger (3) is switched to perform defrosting as a condenser; the refrigerant after the heat is released by the indoor heat exchanger (4) and the refrigerant after the heat is released by the outdoor heat exchanger (3) are mixed, and after being vaporized by heat exchange, they return to the suction side of the compressor.

[0014] Compared with the prior art, the advantages and positive effects of the air-conditioning system are as follows: in the air-conditioning system proposed by the present invention, the first reversing valve (1) is used to switch the state of the outdoor heat exchanger (3) to the condenser or evaporator, and the second reversing valve (2) is used to switch the state of the indoor heat exchanger (4) to the condenser or evaporator; when the air-conditioning system is in normal heating mode, the first reversing valve (1) and the second reversing valve (2) are controlled so that the indoor heat exchanger (4) is used as a condenser and the outdoor heat exchanger (3) is used as an evaporator to implement indoor heating; when the outdoor heat exchanger (3) is frosted until the defrosting condition is met during the heating process, the state of the second reversing valve (2) is kept unchanged to maintain the indoor heating mode. The heating mode of the indoor heat exchanger (4) remains unchanged, that is, the indoor heat exchanger (4) is maintained as a condenser, and the first reversing valve (1) is switched so that the outdoor heat exchanger (3) is switched from an evaporator to a condenser. The heat released is used to defrost the outdoor heat exchanger (3). The refrigerants after the heat released by the indoor heat exchanger (4) and the outdoor heat exchanger (3) are mixed in the pipeline and returned to the suction side of the compressor after being vaporized by heat exchange. During the entire defrosting process, the indoor heat exchanger (4) is still in the heating state of the condenser, avoiding the problem of the traditional switching of the indoor heat exchanger to the evaporator causing the indoor ambient temperature to drop. The defrosting effect is good and does not affect the user's comfort experience.

[0015] In some embodiments of the present invention, the outdoor unit is composed of a compressor (5), a first reversing valve (1), an outdoor heat exchanger (3), a subcooler (7) and a gas-liquid separator (6) connected in series; the second reversing valve (2), its D end and the D end of the first reversing valve (1) are both connected to the exhaust end of the compressor (5), its C end is connected to the indoor heat exchanger (4), and its S end and the S end of the first reversing valve (1) are both connected to the inlet of the gas-liquid separator (6); wherein, the E end of the first reversing valve (1) is connected to the indoor an outdoor heat exchanger (3); and a controller configured to: when the air-conditioning system operates in a heating mode, control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the indoor heat exchanger (4), and the outdoor heat exchanger (3) is connected to the suction side of the compressor (5); and when the air-conditioning system operates in a heating mode and needs to be defrosted, maintain the second reversing valve (2) and switch the first reversing valve (1) so that the exhaust side of the compressor (1) is connected to the outdoor heat exchanger (3).

[0016] Compared with the prior art, the advantages and positive effects of the air-conditioning system are as follows: in the air-conditioning system proposed by the present invention, the first (1) is used to switch the state of the outdoor heat exchanger (3) to the condenser or evaporator, and the second (2) is used to switch the state of the indoor heat exchanger (4) to the condenser or evaporator; when the air-conditioning system is in normal heating mode, the first (1) and the second (2) are controlled so that the exhaust side of the compressor (5) is connected to the indoor heat exchanger (4), and the indoor heat exchanger (4) is used as an evaporator, and the outdoor heat exchanger (3) is connected to the intake side of the compressor (5), and the indoor heat exchanger (4) is used as a condenser; when the outdoor heat exchanger (3) is frosted to meet the defrosting condition during the heating process, the state of the second reversing valve (2) is kept unchanged, and the heating mode of the indoor heat exchanger (4) is kept unchanged, that is, the indoor heat exchanger (4) is kept used as an evaporator, and the first reversing valve is switched. The valve (1) is reversed to connect the exhaust side of the compressor (5) with the outdoor heat exchanger (3), so that the outdoor heat exchanger (3) is switched from an evaporator to a condenser. A part of the high-temperature and high-pressure refrigerant from the compressor (5) enters the indoor heat exchanger (4) to maintain the indoor temperature, and a part enters the outdoor heat exchanger (3) for condensation and heat release. The released heat is used for defrosting. The refrigerant after heat release outdoors passes through the subcooler (7) and returns to the gas-liquid separator (6) and returns to the suction side of the compressor (5). The refrigerant circulating from the indoor heat exchanger (4) also passes through the subcooler (7) and returns to the gas-liquid separator (6) and returns to the suction side of the compressor (5). During the entire defrosting process, the indoor heat exchanger (4) is still in the heating state of the condenser, avoiding the problem of the traditional switching of the indoor heat exchanger to the evaporator causing the indoor ambient temperature to drop. The defrosting effect is good and does not affect the user's comfort experience.

[0017] In the present invention, the subcooler (7) is an existing component of the air-conditioning system. In the cooling mode, the subcooler (7) subcools the refrigerant condensed from the outdoor heat exchanger (3) to ensure that the temperature of the liquid refrigerant entering the indoor heat exchanger (4) is reduced, reducing the flash gas generated during or after throttling, thereby improving the cooling capacity of the system; and combined with the system architecture proposed by the present invention, it provides a new application function. During the heating and defrosting operation, the refrigerant condensed from the outdoor heat exchanger (3) and the indoor heat exchanger (4) are mixed in the subcooler (7), and the high-temperature refrigerant and the low-temperature refrigerant are heat-exchanged to promote gasification and then return to the gas-liquid separator (6). After gas-liquid separation in the gas-liquid separator (6), the gaseous refrigerant returns to the compressor (5).

[0018] In some embodiments of the present invention, the indoor unit further comprises: an indoor fan (9); an indoor electronic expansion valve (101), connected to the indoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); the controller is configured to: when the air-conditioning system operates in a heating mode and requires defrosting, adjust the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101) so that the superheat of the refrigerant after condensation from the indoor heat exchanger (4) does not exceed a first preset superheat; the first preset superheat satisfies that the refrigerant after condensation from the indoor heat exchanger (4) is in a gaseous state or a gas-liquid two-phase state.

[0019] When the air conditioning system is running in the heating mode and needs to be defrosted, the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101) are controlled so that the superheat of the refrigerant after condensing from the indoor heat exchanger (4) does not exceed the first preset superheat, so that the refrigerant after condensing from the indoor heat exchanger (4) has superheat but is not completely condensed into liquid, and maintains a high-temperature gas state or a high-temperature gas-liquid two-phase state, so that after it is mixed with the refrigerant entering the subcooler (7) from the indoor heat exchanger (4), the former promotes the vaporization of the latter with its high temperature, so that the refrigerant entering the gas-liquid separator (6) is all gaseous refrigerant.

[0020] In some embodiments of the present invention, the outdoor unit further comprises: an outdoor electronic expansion valve (102) connected to the outdoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); the controller is configured to: when the air-conditioning system is operating in heating mode and needs to be defrosted, adjust the opening of the outdoor electronic expansion valve (102) to adjust the amount of refrigerant entering the outdoor heat exchanger (3) from the exhaust side of the compressor (5), so that the superheat of the refrigerant condensed from the outdoor heat exchanger (3) and the refrigerant condensed from the indoor heat exchanger (4) after mixing in the supercooler (7) does not exceed a second preset superheat; the second preset superheat satisfies that the mixed refrigerant is in a gaseous state or a gas-liquid two-phase state.

[0021] When the air-conditioning system is running in the heating mode and needs to be defrosted, the outdoor heat exchanger (3) is switched from the evaporator to the condenser. In combination with the frosting situation and the defrosting requirement, the condensation heat release on the outdoor side can be achieved by adjusting the opening of the outdoor electronic expansion valve (102). At the same time, the superheat of the refrigerant condensed from the outdoor heat exchanger (3) and the refrigerant condensed from the indoor heat exchanger (4) after mixing in the supercooler (7) does not exceed the second preset superheat, and the second preset superheat satisfies that the mixed refrigerant is in a gaseous state or a gas-liquid two-phase state; that is, after the refrigerant condensed from the indoor heat exchanger (4) and the refrigerant condensed from the outdoor heat exchanger (3) are mixed in the supercooler (7), the former can promote the complete vaporization of the latter, ensuring that the refrigerant entering the gas-liquid separator (6) is a gaseous refrigerant.

[0022] In some embodiments of the present invention, the outdoor unit further comprises: an EVB expansion valve (103), which is installed on the subcooling branch between the outdoor heat exchanger (3) and the subcooler (7); and the controller is configured to: when the air-conditioning system is operating in a heating mode and requires defrosting, adjust the opening of the EVB expansion valve (103) and the outdoor electronic expansion valve (102) according to the defrosting demand, so as to adjust the amount of refrigerant entering the outdoor heat exchanger (3).

[0023] In this embodiment, the subcooling branch where the EVB expansion valve (103) is located is not used as a subcooling branch, but is used as a refrigerant circuit of the outdoor heat exchanger (3). When the air-conditioning system is running in the heating mode and needs to be defrosted, the outdoor heat exchanger (3) is switched from the evaporator to the condenser. In combination with the frosting situation, the amount of refrigerant entering the outdoor heat exchanger (3) can be adjusted by adjusting the opening of the EVB expansion valve (103) and the outdoor electronic expansion valve (102), and the defrosting effect can be improved based on different refrigerant amounts. When the amount of frost is small, the opening of the EVB expansion valve (103) is adjusted to be smaller, and when the amount of frost is large, the opening of the EVB expansion valve (93) is adjusted to be relatively larger.

[0024] In some embodiments of the present invention, the outdoor unit further comprises: a compressor bypass branch, installed between the exhaust side of the compressor (5) and the inlet of the gas-liquid separator (6), and composed of a bypass solenoid valve (111) and a bypass capillary tube (112) connected in series; and the controller is configured to determine whether to close the bypass solenoid valve (111) to connect the compressor bypass branch according to the overheating state of the suction air of the compressor (5) when the air-conditioning system is operating in a heating mode and needs to be defrosted.

[0025] Based on the air-conditioning system architecture proposed by the present invention, during the entire defrosting process, a large amount of liquid refrigerant will be present in the outdoor heat exchanger (3) and the gas-liquid separator (6), which may cause the exhaust pressure, suction pressure, exhaust temperature, etc. in the air-conditioning system to be lower than the corresponding target values. Whether the bypass solenoid valve (111) needs to be closed can be determined based on the overheating state of the suction of the compressor (5). By closing the bypass solenoid valve (111), the compressor bypass branch is connected, so that part of the high-temperature and high-pressure refrigerant discharged from the compressor (5) enters the gas-liquid separator (6) to promote the gasification of the liquid refrigerant, increase the refrigerant suction volume of the compressor (5), avoid the compressor (5) suctioning back the liquid and affecting its reliability, and ensure the stable and reliable operation of the unit.

[0026] In some embodiments of the present invention, the outdoor unit further comprises three refrigerant pipelines: a high-pressure gas pipeline (121), a low-pressure gas pipeline (122) and a liquid return pipeline (123); wherein the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122) are both connected to the exhaust side of the compressor (5), and the liquid return pipeline (123) is connected to the suction side of the compressor (5); the indoor unit further comprises: a heat exchanger (13) connected to the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122) of the outdoor unit. The controller is connected between the high-pressure gas pipeline (121) and the indoor heat exchanger (4); it includes an expansion valve for controlling the on / off of the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122), and a bypass capillary between the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122); the controller is configured to: when the air-conditioning system operates in the heating mode or defrosts in the heating mode, control the expansion valve on the high-pressure gas pipeline (121) side to open and the expansion valve on the low-pressure gas pipeline (122) side to close, so that the indoor unit gas pipe is connected to the high-pressure gas pipeline (121).

[0027] Based on the air-conditioning system provided in the embodiment of the present invention, combined with the control of the expansion valves on the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122) of the cold-heat converter (13), it is possible to realize the simultaneous operation of cooling and heating of multiple indoor units, and the outdoor heat exchanger (3) can be flexibly switched between cooling mode, heating mode and defrosting in heating mode, and can take into account the application of a two-pipe air-conditioning system and a three-pipe air-conditioning system at the same time, thereby improving the flexibility and scalability of the air-conditioning system.

[0028] In some embodiments of the present invention, the C end and the S end of the first reversing valve (1) are short-circuited via a first capillary tube (81); and / or the E end and the S end of the second reversing valve (2) are short-circuited via a second capillary tube (82).

[0029] Since the first reversing valve (1) does not need to be reversed regardless of whether it is in the heating process or in the heating defrosting process, refrigerant liquid may accumulate at the idle end of the first reversing valve (1). In order to ensure that the first reversing valve (1) is smoothly operated without being obstructed by liquid refrigerant during the reversing process, a first capillary tube (81) is added between the C end and the S end thereof. The first capillary tube (81) bypasses the accumulated refrigerant to the gas-liquid separator (6), thereby preventing the accumulated refrigerant liquid from obstructing the reversing of the first reversing valve (1). Similarly, in some embodiments of the present invention, since the second reversing valve (2) does not need to be reversed during the refrigeration process, refrigerant liquid may accumulate at the idle end of the second reversing valve (2). In order to ensure that the second reversing valve (2) is smoothly operated without being obstructed by liquid refrigerant during the reversing process, a second capillary tube (82) is added between the E end and the S end thereof. The second capillary tube (82) bypasses the accumulated refrigerant to the gas-liquid separator (6), thereby preventing the accumulated refrigerant liquid from obstructing the reversing of the second reversing valve (2).

[0030] Other features and advantages of the present invention will become more apparent after reading the detailed description of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] Figure 1 This is a schematic diagram of the system architecture of the air-conditioning system proposed in the present invention;

[0033] Figure 2 This is a schematic diagram of the refrigerant flow direction of the air-conditioning system proposed by the present invention in cooling mode;

[0034] Figure 3 This is a schematic diagram of the refrigerant flow direction of the air-conditioning system proposed by the present invention in heating mode;

[0035] Figure 4 This is a schematic diagram of the refrigerant flow direction of the air-conditioning system proposed by the present invention during defrosting in heating mode;

[0036] Figure 5 This is a schematic diagram of the system architecture of an air-conditioning system according to the first embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram of the system architecture of an air-conditioning system according to the second embodiment of the present invention;

[0038] Figure 7 This is a schematic diagram of the system architecture of an air-conditioning system according to the third embodiment of the present invention;

[0039] Figure 8 This is a schematic diagram of the system architecture of an air-conditioning system according to a fourth embodiment of the present invention;

[0040] Figure 9 This is a schematic diagram of the system architecture of an air-conditioning system according to a fifth embodiment of the present invention;

[0041] Figure 10 This is a schematic diagram of the internal structure of the heat-cooling converter (13) in the air-conditioning system according to the fifth embodiment of the present invention;

[0042] Figure 11 This is a schematic diagram of the system architecture of an air-conditioning system according to the sixth embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0044] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0045] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0046] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0047] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0048] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0049] The present invention aims to propose a technical solution based on the existing air-conditioning system architecture: defrosting the outdoor heat exchanger without changing the heating mode, achieving the effect of defrosting without cooling, and improving the heating comfort of the air-conditioning system.

[0050] Based on the above technical objectives, the air-conditioning system proposed in the present invention switches the state of the outdoor heat exchanger to condenser or evaporator through the first reversing valve, and switches the state of the indoor heat exchanger to condenser or evaporator through the second reversing valve. When the air-conditioning system operates in heating mode, the controller is configured to control the first reversing valve and the second reversing valve, so that the indoor heat exchanger is used as a condenser and the outdoor heat exchanger is used as an evaporator. When defrosting is required in the heating mode, the second reversing valve is maintained at the same state, and the first reversing valve is controlled to switch the outdoor heat exchanger from evaporator to condenser. The outdoor heat exchanger can defrost its surface due to the heat release of the refrigerant. During this period, the refrigerant after heat release by the indoor heat exchanger and the refrigerant after heat release by the outdoor heat exchanger are mixed and returned to the suction side of the compressor after heat exchange and vaporization.

[0051] During the entire defrosting process, the indoor heat exchanger (4) is still in the heating state of the condenser, thus avoiding the problem of the indoor ambient temperature dropping caused by the traditional switching of the indoor heat exchanger to the evaporator. The defrosting effect is good and does not affect the user's comfort experience.

[0052] Specifically, such as Figure 1As shown, the air conditioning system proposed in some embodiments of the present invention includes:

[0053] An outdoor unit and an indoor unit; wherein the indoor unit includes an indoor heat exchanger (4); and the outdoor unit includes a compressor (5), a first reversing valve (1), an outdoor heat exchanger (3), a subcooler (7), and a gas-liquid separator (6) connected in series.

[0054] The D end of the first reversing valve (1) is connected to the exhaust end of the compressor (5), the E end is connected to the outdoor heat exchanger (3), the S end is connected to the inlet of the gas-liquid separator (6), and the C end is idle.

[0055] The D end of the second reversing valve (2) is connected to the exhaust end of the compressor (5), the C end thereof is connected to the indoor heat exchanger (4), and the S end thereof and the S end of the first reversing valve (1) are both connected to the inlet of the gas-liquid separator (6). The E end of the first reversing valve (1) is connected to the outdoor heat exchanger (3), and the E end is idle.

[0056] In the air-conditioning system proposed in the present invention, the state of the outdoor heat exchanger (3) is switched between the condenser and the evaporator via the first reversing valve (1), and the state of the indoor heat exchanger (4) is switched between the condenser and the evaporator via the second reversing valve (2). A controller (not shown in the figure) switches the states of the first reversing valve (1) and the second reversing valve (2) and supports the operation of the entire system, so that the operation modes of the air-conditioning system include but are not limited to: cooling mode, heating mode, and defrosting in heating mode.

[0057] like Figure 2 As shown, in the cooling mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the outdoor heat exchanger (3), and the indoor heat exchanger (4) is connected to the suction side of the compressor (5). Specifically, the D end of the first reversing valve (1) is controlled to be connected to the E end, and the C end of the second reversing valve (2) is controlled to be connected to the S end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gas and discharges it. The gaseous refrigerant enters the outdoor heat exchanger (3) through the first reversing valve (1), releases heat in the outdoor heat exchanger (3), and condenses into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant enters the subcooler (7) after being depressurized and throttled by the outdoor electronic expansion valve, and enters the indoor heat exchanger (4) after being supercooled by the cooler (7). The gaseous refrigerant absorbs heat and evaporates into a gaseous refrigerant in the indoor heat exchanger (4). The gaseous refrigerant returns to the gas-liquid separator (6) through the second low-pass valve (2), and returns to the suction side of the compressor (5).

[0058] like Figure 3As shown, in the heating mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the indoor heat exchanger (4), and the outdoor heat exchanger (3) is connected to the suction side of the compressor (5). Specifically, the E end of the first reversing valve (1) is controlled to be connected to the S end, and the D end of the second reversing valve (2) is controlled to be connected to the C end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure gas and discharges it. The gaseous refrigerant enters the indoor heat exchanger (4) through the second reversing valve (2), releases heat in the indoor heat exchanger (4), and condenses into high-pressure liquid refrigerant. The high-pressure liquid refrigerant enters the outdoor heat exchanger (3) after being reduced in pressure and throttled by the indoor electronic expansion valve. The gaseous refrigerant absorbs heat and evaporates into gaseous refrigerant in the outdoor heat exchanger (3). The gaseous refrigerant returns to the gas-liquid separator (6) through the first low-pass valve (1) and returns to the suction side of the compressor (5).

[0059] like Figure 4 As shown, when the outdoor heat exchanger (3) is frosted to the point where the defrosting condition is met during the heating process of the air-conditioning system, the defrosting operation in the heating mode is started. The controller is configured to: maintain the second reversing valve (2) and switch the first reversing valve (1) so that the exhaust side of the compressor (1) is connected to the outdoor heat exchanger (3). Specifically, the connection state between the D end and the C end of the second reversing valve (2) is maintained unchanged, the heating mode of the indoor heat exchanger (4) is maintained unchanged, that is, the indoor heat exchanger (4) is maintained as an evaporator, and the first reversing valve (1) is switched so that the D end and the E end are connected, thereby connecting the exhaust side of the compressor (5) to the outdoor heat exchanger (3), so that the outdoor heat exchanger (3) is switched from an evaporator to a condenser.

[0060] A portion of the high-temperature and high-pressure refrigerant coming out of the compressor (5) (e.g. Figure 4 The heat released by the heat exchanger (4) is used to heat the room or maintain the room temperature; a portion (such as Figure 4 The heat released by the heat exchanger (shown by the black arrow in the middle) enters the outdoor heat exchanger (3) for condensation and releases heat, and the heat released defrosts its surface.

[0061] The refrigerant condensed in the outdoor heat exchanger (3) passes through the subcooler (7) and returns to the gas-liquid separator (6), and then returns to the suction side of the compressor (5); the refrigerant circulating from the indoor heat exchanger (4) also passes through the subcooler (7) and returns to the gas-liquid separator (6), and then returns to the suction side of the compressor (5); during the entire defrosting process, the indoor heat exchanger (4) remains in the heating state of the condenser, avoiding the problem of the traditional switching of the indoor heat exchanger to the evaporator causing the indoor ambient temperature to drop, and the defrosting effect is good without affecting the user's comfort experience.

[0062] It should be noted that the defrost conditions herein refer to the defrost conditions of existing air-conditioning outdoor units and are not limited by the present invention.

[0063] In the embodiment of the present invention, the subcooler (7) is an existing component of the air-conditioning system. In the cooling mode, the subcooler (7) subcools the refrigerant condensed from the outdoor heat exchanger (3) to ensure that the temperature of the liquid refrigerant entering the indoor heat exchanger (4) is reduced, reducing the flash gas generated during or after throttling, thereby improving the cooling capacity of the system; and combined with the system architecture proposed by the present invention, it provides a new application function. During the heating and defrosting operation, the refrigerant condensed from the outdoor heat exchanger (3) and the indoor heat exchanger (4) are mixed in the subcooler (7), and the high-temperature refrigerant and the low-temperature refrigerant exchange heat to promote their vaporization and return to the gas-liquid separator (6). After gas-liquid separation in the gas-liquid separator (6), the gaseous refrigerant returns to the compressor (5).

[0064] That is, in the embodiment of the present invention, the cooler (7) does not play a supercooling role during the heating and defrosting period, but rather allows the refrigerant condensed from the outdoor heat exchanger (3) and the refrigerant condensed from the indoor heat exchanger (4) to mix therein, and interact with each other to promote heat exchange and gasification and then return to the gas-liquid separator (6), thereby reducing the accumulation of liquid refrigerant in the gas-liquid separator (6), avoiding the compressor suction and liquid return affecting stability, stabilizing the system refrigerant amount, and thus ensuring the heating and defrosting effects.

[0065] The defrosting process in the heating mode of the air-conditioning system proposed by the present invention is described in detail below with reference to several specific embodiments.

[0066] Example 1

[0067] like Figure 5 As shown, the air conditioning system proposed in this embodiment includes:

[0068] An outdoor unit and an indoor unit; wherein the indoor unit includes an indoor heat exchanger (4); and the outdoor unit includes a compressor (5), a first reversing valve (1), an outdoor heat exchanger (3), a subcooler (7), and a gas-liquid separator (6) connected in series.

[0069] The D end of the first reversing valve (1) is connected to the exhaust end of the compressor (5), the E end is connected to the outdoor heat exchanger (3), the S end is connected to the inlet of the gas-liquid separator (6), and the C end is idle.

[0070] The D end of the second reversing valve (2) is connected to the exhaust end of the compressor (5), the C end thereof is connected to the indoor heat exchanger (4), and the S end thereof and the S end of the first reversing valve (1) are both connected to the inlet of the gas-liquid separator (6). The E end of the first reversing valve (1) is connected to the outdoor heat exchanger (3), and the E end is idle.

[0071] The indoor fan (9) is used to operate according to a set air volume to blow hot air or cold air into the room.

[0072] The indoor electronic expansion valve (101) is connected to the indoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); and is used to throttle and reduce the pressure of the refrigerant condensed from the indoor heat exchanger (4) in the heating mode.

[0073] In the cooling mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the outdoor heat exchanger (3), and the indoor heat exchanger (4) is connected to the suction side of the compressor (5). Specifically, the D end of the first reversing valve (1) is controlled to be connected to the E end, and the C end of the second reversing valve (2) is controlled to be connected to the S end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure gas and discharges it. The gaseous refrigerant enters the outdoor heat exchanger (3) through the first reversing valve (1), releases heat in the outdoor heat exchanger (3), and condenses into high-pressure liquid refrigerant. The high-pressure liquid refrigerant enters the subcooler (7) after pressure reduction and throttling by the outdoor electronic expansion valve, and enters the indoor heat exchanger (4) after being supercooled by the cooler (7). The gaseous refrigerant absorbs heat in the indoor heat exchanger (4) and evaporates into gaseous refrigerant. The gaseous refrigerant returns to the gas-liquid separator (6) through the second low-pass valve (2), and returns to the suction side of the compressor (5).

[0074] In the heating mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the indoor heat exchanger (4), and the outdoor heat exchanger (3) is connected to the suction side of the compressor (5). Specifically, the E end of the first reversing valve (1) is controlled to be connected to the S end, and the D end of the second reversing valve (2) is controlled to be connected to the C end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure gas and discharges it into the indoor heat exchanger (4) through the second reversing valve (2). In the indoor heat exchanger (4), heat is released and condensed into high-pressure liquid refrigerant. The high-pressure liquid refrigerant enters the outdoor heat exchanger (3) after pressure reduction and throttling by the indoor electronic expansion valve (101). In the outdoor heat exchanger (3), heat is absorbed and evaporated into gaseous refrigerant. The gaseous refrigerant returns to the gas-liquid separator (6) through the first low-pass valve (1) and returns to the suction side of the compressor (5).

[0075] The air-conditioning system starts a defrosting operation in the heating mode when the outdoor heat exchanger (3) is frosted to the point where the defrosting condition is met during the heating process. The controller is configured to: maintain the second reversing valve (2) and switch the first reversing valve (1) so that the exhaust side of the compressor (1) is connected to the outdoor heat exchanger (3). Specifically, the connection state between the D end and the C end of the second reversing valve (2) is maintained unchanged, the heating mode of the indoor heat exchanger (4) is maintained unchanged, that is, the indoor heat exchanger (4) is maintained as an evaporator, and the first reversing valve (1) is switched so that the D end and the E end are connected, thereby connecting the exhaust side of the compressor (5) to the outdoor heat exchanger (3), so that the outdoor heat exchanger (3) is switched from an evaporator to a condenser.

[0076] Furthermore, the controller is further configured to adjust the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101) so that the superheat of the refrigerant after condensation from the indoor heat exchanger (4) does not exceed a first preset superheat; the first preset superheat is required to satisfy the requirement that the refrigerant after condensation from the indoor heat exchanger (4) is in a gaseous state or a gas-liquid two-phase state.

[0077] A portion of the high-temperature and high-pressure refrigerant coming out of the compressor (5) enters the indoor heat exchanger (4), where it releases heat and condenses, and the released heat is used to heat the room or maintain the indoor temperature; a portion enters the outdoor heat exchanger (3), where it condenses and releases heat, and the released heat is used to defrost its surface.

[0078] The refrigerant condensed in the outdoor heat exchanger (3) enters the subcooler (7), and the refrigerant condensed in the indoor heat exchanger (4) also enters the subcooler (7). In this embodiment, by controlling the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101), the superheat of the refrigerant condensed from the indoor heat exchanger (4) does not exceed the first preset superheat, so that the refrigerant condensed from the indoor heat exchanger (4) does not have superheat but does not condense into liquid, and maintains a high-temperature gas state or a high-temperature gas-liquid two-phase state, so as to achieve its After the refrigerant in the subcooler (7) is mixed with the refrigerant entering the subcooler (7) from the indoor heat exchanger (4), the former causes the latter to vaporize with its high temperature, so that the refrigerant entering the gas-liquid separator (6) is a gaseous refrigerant; the gaseous refrigerant returns to the suction side of the compressor (5) from the gas-liquid separator (6); during the entire defrosting process, the indoor heat exchanger (4) is still in the heating state of the condenser, avoiding the problem of the traditional switching of the indoor heat exchanger to the evaporator causing the indoor ambient temperature to drop, and the defrosting effect is good without affecting the user's comfort experience.

[0079] In this embodiment, the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101) are adjusted so that the superheat of the refrigerant after condensation from the indoor heat exchanger (4) does not exceed the first preset superheat. For example, the indoor fan (9) is adjusted to the minimum air volume or stopped. The specific adjustment parameters are set according to the actual application conditions and are not limited by this embodiment.

[0080] Example 2

[0081] like Figure 6 As shown, the air conditioning system proposed in this embodiment includes:

[0082] An outdoor unit and an indoor unit; wherein the indoor unit includes an indoor heat exchanger (4); and the outdoor unit includes a compressor (5), a first reversing valve (1), an outdoor heat exchanger (3), a subcooler (7), and a gas-liquid separator (6) connected in series.

[0083] The D end of the first reversing valve (1) is connected to the exhaust end of the compressor (5), the E end is connected to the outdoor heat exchanger (3), the S end is connected to the inlet of the gas-liquid separator (6), and the C end is idle.

[0084] The D end of the second reversing valve (2) is connected to the exhaust end of the compressor (5), the C end thereof is connected to the indoor heat exchanger (4), and the S end thereof and the S end of the first reversing valve (1) are both connected to the inlet of the gas-liquid separator (6). The E end of the first reversing valve (1) is connected to the outdoor heat exchanger (3), and the E end is idle.

[0085] The indoor fan (9) is used to operate according to a set air volume to blow hot air during heating or cold air during cooling into the room.

[0086] The indoor electronic expansion valve (101) is connected to the indoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); and is used to throttle and reduce the pressure of the refrigerant condensed from the indoor heat exchanger (4) in the heating mode.

[0087] The outdoor electronic expansion valve (102) is connected to the outdoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); and is used to throttle and reduce the pressure of the refrigerant condensed from the outdoor heat exchanger (3) in the cooling mode.

[0088] In the cooling mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the outdoor heat exchanger (3), and the indoor heat exchanger (4) is connected to the suction side of the compressor (5). Specifically, the D end of the first reversing valve (1) is controlled to be connected to the E end, and the C end of the second reversing valve (2) is controlled to be connected to the S end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure gas and discharges it. The gas enters the outdoor heat exchanger (3) through the first reversing valve (1), releases heat in the outdoor heat exchanger (3), and condenses into high-pressure liquid refrigerant. The high-pressure liquid refrigerant enters the subcooler (7) after pressure reduction and throttling by the outdoor electronic expansion valve (102), and enters the indoor heat exchanger (4) after being supercooled by the subcooler (7). The gaseous refrigerant absorbs heat and evaporates into gaseous refrigerant in the indoor heat exchanger (4). The gaseous refrigerant returns to the gas-liquid separator (6) through the second low-pass valve (2), and returns to the suction side of the compressor (5).

[0089] In the heating mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the indoor heat exchanger (4), and the outdoor heat exchanger (3) is connected to the suction side of the compressor (5). Specifically, the E end of the first reversing valve (1) is controlled to be connected to the S end, and the D end of the second reversing valve (2) is controlled to be connected to the C end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure gas and discharges it into the indoor heat exchanger (4) through the second reversing valve (2). In the indoor heat exchanger (4), heat is released and condensed into high-pressure liquid refrigerant. The high-pressure liquid refrigerant enters the outdoor heat exchanger (3) after pressure reduction and throttling by the indoor electronic expansion valve (101). In the outdoor heat exchanger (3), heat is absorbed and evaporated into gaseous refrigerant. The gaseous refrigerant returns to the gas-liquid separator (6) through the first low-pass valve (1) and returns to the suction side of the compressor (5).

[0090] The air-conditioning system starts a defrosting operation in the heating mode when the outdoor heat exchanger (3) is frosted to the point where the defrosting condition is met during the heating process. The controller is configured to: maintain the second reversing valve (2) and switch the first reversing valve (1) so that the exhaust side of the compressor (1) is connected to the outdoor heat exchanger (3). Specifically, the connection state between the D end and the C end of the second reversing valve (2) is maintained unchanged, the heating mode of the indoor heat exchanger (4) is maintained unchanged, that is, the indoor heat exchanger (4) is maintained as an evaporator, and the first reversing valve (1) is switched so that the D end and the E end are connected, thereby connecting the exhaust side of the compressor (5) to the outdoor heat exchanger (3), so that the outdoor heat exchanger (3) is switched from an evaporator to a condenser.

[0091] Furthermore, the controller is further configured to: 1. adjust the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101) so that the superheat of the refrigerant after condensing from the indoor heat exchanger (4) does not exceed a first preset superheat; the first preset superheat is required to satisfy that the refrigerant after condensing from the indoor heat exchanger (4) is in a gaseous state. 2. adjust the opening of the outdoor electronic expansion valve (102) to adjust the amount of refrigerant entering the outdoor heat exchanger (3) from the exhaust side of the compressor (5) so that the superheat of the refrigerant after condensing from the outdoor heat exchanger (3) and the refrigerant after condensing from the indoor heat exchanger (4) after mixing in the subcooler (7) does not exceed a second preset superheat; the second preset superheat is required to satisfy that the refrigerant after mixing is in a gaseous state or a gas-liquid two-phase state.

[0092] A portion of the high-temperature and high-pressure refrigerant coming out of the compressor (5) enters the indoor heat exchanger (4), where it releases heat and condenses, and the released heat is used to heat the room or maintain the indoor temperature; a portion enters the outdoor heat exchanger (3), where it condenses and releases heat, and the released heat is used to defrost its surface.

[0093] The refrigerant condensed in the outdoor heat exchanger (3) enters the subcooler (7), and the refrigerant condensed in the indoor heat exchanger (4) also enters the subcooler (7). In this embodiment, by controlling the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101), the superheat of the refrigerant condensed from the indoor heat exchanger (4) does not exceed the first preset superheat, so that the refrigerant condensed from the indoor heat exchanger (4) has superheat but does not condense into liquid, and maintains a high-temperature gas state or a high-temperature gas-liquid two-phase state, so that after it is mixed with the refrigerant entering the subcooler (7) from the indoor heat exchanger (4), the former promotes the vaporization of the latter with its high temperature, so that the refrigerant entering the gas-liquid separator (6) is a gaseous refrigerant.

[0094] Furthermore, in combination with the frosting situation and the defrosting requirement, the condensation heat release on the outdoor side can be achieved by adjusting the opening of the outdoor electronic expansion valve (102). At the same time, the superheat of the refrigerant condensed from the outdoor heat exchanger (3) and the refrigerant condensed from the indoor heat exchanger (4) after mixing in the supercooler (7) does not exceed a second preset superheat, and the second preset superheat satisfies that the mixed refrigerant is in a gaseous state or a gas-liquid two-phase state; that is, after the refrigerant condensed from the indoor heat exchanger (4) and the refrigerant condensed from the outdoor heat exchanger (3) are mixed in the supercooler (7), the former can promote the complete vaporization of the latter, thereby ensuring that the refrigerant entering the gas-liquid separator (6) is a gaseous refrigerant.

[0095] The gaseous refrigerant returns to the suction side of the compressor (5) through the gas-liquid separator (6); during the entire defrosting process, the indoor heat exchanger (4) is still in the heating state of the condenser, avoiding the problem of the traditional switching of the indoor heat exchanger to the evaporator causing the indoor ambient temperature to drop, and the defrosting effect is good without affecting the user's comfort experience.

[0096] In this embodiment, the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101) are adjusted so that the superheat of the refrigerant after condensing from the indoor heat exchanger (4) does not exceed the first preset superheat as a basis, for example, the indoor fan (9) is adjusted to the minimum air volume or stopped. The specific adjustment parameters are set according to the actual application conditions and are not limited to the part of this embodiment. Similarly, the opening of the outdoor electronic expansion valve (102) is adjusted so that the superheat of the refrigerant after condensing from the outdoor heat exchanger (3) and the refrigerant after condensing from the indoor heat exchanger (04) does not exceed the second preset superheat after mixing in the subcooler (7). The specific adjustment parameters are set according to the actual application conditions and are not limited to the part of this embodiment.

[0097] Typically, the second preset superheat does not exceed the first preset superheat.

[0098] Example 3

[0099] like Figure 7As shown, the air conditioning system proposed in this embodiment includes:

[0100] An outdoor unit and an indoor unit; wherein the indoor unit includes an indoor heat exchanger (4); and the outdoor unit includes a compressor (5), a first reversing valve (1), an outdoor heat exchanger (3), a subcooler (7), and a gas-liquid separator (6) connected in series.

[0101] The D end of the first reversing valve (1) is connected to the exhaust end of the compressor (5), the E end is connected to the outdoor heat exchanger (3), the S end is connected to the inlet of the gas-liquid separator (6), and the C end is idle.

[0102] The D end of the second reversing valve (2) is connected to the exhaust end of the compressor (5), the C end thereof is connected to the indoor heat exchanger (4), and the S end thereof and the S end of the first reversing valve (1) are both connected to the inlet of the gas-liquid separator (6). The E end of the first reversing valve (1) is connected to the outdoor heat exchanger (3), and the E end is idle.

[0103] The indoor fan (9) is used to operate according to a set air volume to blow hot air during heating or cold air during cooling into the room.

[0104] The indoor electronic expansion valve (101) is connected to the indoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); and is used to throttle and reduce the pressure of the refrigerant condensed from the indoor heat exchanger (4) in the heating mode.

[0105] The outdoor electronic expansion valve (102) is connected to the outdoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); and is used to throttle and reduce the pressure of the refrigerant condensed from the outdoor heat exchanger (3) in the cooling mode.

[0106] The EVB expansion valve (103) is installed on the subcooling branch between the outdoor heat exchanger (3) and the subcooler (7). Typically, in cooling mode, part of the refrigerant condensed from the outdoor heat exchanger (3) enters the subcooler (7) from the e end, exits from the g end after being subcooled, and enters the main refrigeration circuit of the indoor heat exchanger (4). Part of the refrigerant passes through the cold branch and enters the subcooler (7) from the f end, exits from the h end after heat exchange, and returns to the suction side of the compressor (5) after passing through the gas-liquid separator (6).

[0107] In the cooling mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the outdoor heat exchanger (3), and the indoor heat exchanger (4) is connected to the suction side of the compressor (5). Specifically, the D end of the first reversing valve (1) is controlled to be connected to the E end, and the C end of the second reversing valve (2) is controlled to be connected to the S end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure gas and discharges it. The gaseous refrigerant enters the outdoor heat exchanger (3) through the first reversing valve (1), releases heat in the outdoor heat exchanger (3), and condenses into high-pressure liquid refrigerant. After the high-pressure liquid refrigerant is reduced in pressure and throttled by the outdoor electronic expansion valve (102), a portion enters the subcooler (7) from the e end, exits from the g end after being supercooled, and enters the main refrigeration circuit of the indoor heat exchanger (4), absorbs heat in the indoor heat exchanger (4) and evaporates into gaseous refrigerant. The gaseous refrigerant returns to the gas-liquid separator (6) through the second low-pass valve (2) and returns to the suction side of the compressor (5); a portion enters the subcooler (7) from the f end through the cold branch, exits from the h end after heat exchange, and returns to the suction side of the compressor (5) after passing through the gas-liquid separator (6).

[0108] In the heating mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the indoor heat exchanger (4), and the outdoor heat exchanger (3) is connected to the suction side of the compressor (5). Specifically, the E end of the first reversing valve (1) is controlled to be connected to the S end, and the D end of the second reversing valve (2) is controlled to be connected to the C end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure gas and discharges it into the indoor heat exchanger (4) through the second reversing valve (2). In the indoor heat exchanger (4), heat is released and condensed into high-pressure liquid refrigerant. The high-pressure liquid refrigerant enters the outdoor heat exchanger (3) after pressure reduction and throttling by the indoor electronic expansion valve (101). In the outdoor heat exchanger (3), heat is absorbed and evaporated into gaseous refrigerant. The gaseous refrigerant returns to the gas-liquid separator (6) through the first low-pass valve (1) and returns to the suction side of the compressor (5).

[0109] The air-conditioning system starts a defrosting operation in the heating mode when the outdoor heat exchanger (3) is frosted to the point where the defrosting condition is met during the heating process. The controller is configured to: maintain the second reversing valve (2) and switch the first reversing valve (1) so that the exhaust side of the compressor (1) is connected to the outdoor heat exchanger (3). Specifically, the connection state between the D end and the C end of the second reversing valve (2) is maintained unchanged, the heating mode of the indoor heat exchanger (4) is maintained unchanged, that is, the indoor heat exchanger (4) is maintained as an evaporator, and the first reversing valve (1) is switched so that the D end and the E end are connected, thereby connecting the exhaust side of the compressor (5) to the outdoor heat exchanger (3), so that the outdoor heat exchanger (3) is switched from an evaporator to a condenser.

[0110] In this embodiment, the controller is further configured to: 1. adjust the opening of the EVB expansion valve (103) according to the defrosting demand, the amount of frost, etc., and adjust the amount of refrigerant entering the outdoor heat exchanger (3) in combination with the adjustment of the opening of the outdoor electronic expansion valve (102), thereby improving the defrosting effect of the outdoor heat exchanger (3).

[0111] At the same time, 2. the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101) are adjusted so that the superheat of the refrigerant after condensing from the indoor heat exchanger (4) does not exceed a first preset superheat; the first preset superheat is required to satisfy that the refrigerant after condensing from the indoor heat exchanger (4) is in a gaseous state or a gas-liquid two-phase state. 3. the opening of the outdoor electronic expansion valve (102) is adjusted to adjust the amount of refrigerant entering the outdoor heat exchanger (3) from the exhaust side of the compressor (5) so that the superheat of the refrigerant after condensing from the outdoor heat exchanger (3) and the refrigerant after condensing from the indoor heat exchanger (4) after mixing in the subcooler (7) does not exceed a second preset superheat; the second preset superheat is required to satisfy that the refrigerant after mixing is in a gaseous state or a gas-liquid two-phase state.

[0112] A portion of the high-temperature and high-pressure refrigerant coming out of the compressor (5) enters the indoor heat exchanger (4), where it releases heat and condenses, and the released heat is used to heat the room or maintain the indoor temperature; a portion enters the outdoor heat exchanger (3), where it condenses and releases heat, and the released heat is used to defrost its surface.

[0113] The refrigerant condensed in the outdoor heat exchanger (3) enters the subcooler (7), and the refrigerant condensed in the indoor heat exchanger (4) also enters the subcooler (7). By controlling the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101), the superheat of the refrigerant condensed from the indoor heat exchanger (4) does not exceed a first preset superheat, so that the refrigerant condensed from the indoor heat exchanger (4) has superheat but does not condense into liquid, and maintains a high-temperature gas state or a high-temperature gas-liquid two-phase state, so that after it is mixed with the refrigerant entering the subcooler (7) from the indoor heat exchanger (4), the former promotes the vaporization of the latter with its high temperature, so that the refrigerant entering the gas-liquid separator (6) is a gaseous refrigerant or a gas-liquid two-phase state.

[0114] Furthermore, in combination with the frosting situation and the defrosting requirement, the condensation heat release on the outdoor side is achieved by adjusting the opening of the outdoor electronic expansion valve (102) and / or the EVB expansion valve (103). At the same time, the superheat of the refrigerant condensed from the outdoor heat exchanger (3) and the refrigerant condensed from the indoor heat exchanger (4) after mixing in the supercooler (7) does not exceed a second preset superheat, and the second preset superheat satisfies that the mixed refrigerant is in a gaseous state or a gas-liquid two-phase state; that is, after the refrigerant condensed from the indoor heat exchanger (4) and the refrigerant condensed from the outdoor heat exchanger (3) are mixed in the supercooler (7), the former can promote the vaporization of the latter, thereby ensuring that the refrigerant entering the gas-liquid separator (6) is completely a gaseous refrigerant or a gas-liquid two-phase state.

[0115] The gaseous refrigerant returns from the gas-liquid separator (6) to the suction side of the compressor (5); during the entire defrosting process, the indoor heat exchanger (4) is still in the heating state of the condenser, avoiding the problem of the traditional switching of the indoor heat exchanger to the evaporator causing the indoor ambient temperature to drop, and the defrosting effect is good without affecting the user's comfort experience.

[0116] In this embodiment, the subcooling branch where the EVB expansion valve (103) is located is not used as a subcooling branch, but is used as a refrigerant circuit of the outdoor heat exchanger (3). When the air-conditioning system is running in the heating mode and needs to be defrosted, the outdoor heat exchanger (3) is switched from the evaporator to the condenser. In combination with the frosting situation, the amount of refrigerant entering the outdoor heat exchanger (3) can be adjusted by adjusting the opening of the EVB expansion valve (103), and the defrosting effect can be improved based on different refrigerant amounts. When the amount of frost is small, the opening of the EVB expansion valve (103) is adjusted to be smaller, and when the amount of frost is large, the opening of the EVB expansion valve (93) is adjusted to be relatively larger.

[0117] Example 4

[0118] like Figure 8 As shown, the air conditioning system proposed in this embodiment includes:

[0119] An outdoor unit and an indoor unit; wherein the indoor unit includes an indoor heat exchanger (4); and the outdoor unit includes a compressor (5), a first reversing valve (1), an outdoor heat exchanger (3), a subcooler (7), and a gas-liquid separator (6) connected in series.

[0120] The D end of the first reversing valve (1) is connected to the exhaust end of the compressor (5), the E end is connected to the outdoor heat exchanger (3), the S end is connected to the inlet of the gas-liquid separator (6), and the C end is idle.

[0121] The D end of the second reversing valve (2) is connected to the exhaust end of the compressor (5), the C end thereof is connected to the indoor heat exchanger (4), and the S end thereof and the S end of the first reversing valve (1) are both connected to the inlet of the gas-liquid separator (6). The E end of the first reversing valve (1) is connected to the outdoor heat exchanger (3), and the E end is idle.

[0122] The indoor fan (9) is used to operate according to a set air volume to blow hot air during heating or cold air during cooling into the room.

[0123] The indoor electronic expansion valve (101) is connected to the indoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); and is used to throttle and reduce the pressure of the refrigerant condensed from the indoor heat exchanger (4) in the heating mode.

[0124] The outdoor electronic expansion valve (102) is connected to the outdoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); and is used to throttle and reduce the pressure of the refrigerant condensed from the outdoor heat exchanger (3) in the cooling mode.

[0125] The EVB expansion valve (103) is installed on the subcooling branch between the outdoor heat exchanger (3) and the subcooler (7). Typically, in cooling mode, part of the refrigerant condensed from the outdoor heat exchanger (3) enters the subcooler (7) from the e end, exits from the g end after being subcooled, and enters the main refrigeration circuit of the indoor heat exchanger (4). Part of the refrigerant passes through the cold branch and enters the subcooler (7) from the f end, exits from the h end after heat exchange, and returns to the suction side of the compressor (5) after passing through the gas-liquid separator (6).

[0126] The compressor bypass branch is installed between the exhaust side of the compressor (5) and the inlet of the gas-liquid separator (6), and is composed of a bypass solenoid valve (111) and a bypass capillary tube (112) connected in series.

[0127] In the cooling mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the outdoor heat exchanger (3), and the indoor heat exchanger (4) is connected to the suction side of the compressor (5). Specifically, the D end of the first reversing valve (1) is controlled to be connected to the E end, and the C end of the second reversing valve (2) is controlled to be connected to the S end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure gas and discharges it. The gaseous refrigerant enters the outdoor heat exchanger (3) through the first reversing valve (1), releases heat in the outdoor heat exchanger (3), and condenses into high-pressure liquid refrigerant. After the high-pressure liquid refrigerant is reduced in pressure and throttled by the outdoor electronic expansion valve (102), a portion enters the subcooler (7) from the e end, exits from the g end after being supercooled, and enters the main refrigeration circuit of the indoor heat exchanger (4), absorbs heat in the indoor heat exchanger (4) and evaporates into gaseous refrigerant. The gaseous refrigerant returns to the gas-liquid separator (6) through the second low-pass valve (2) and returns to the suction side of the compressor (5); a portion enters the subcooler (7) from the f end through the cold branch, exits from the h end after heat exchange, and returns to the suction side of the compressor (5) after passing through the gas-liquid separator (6).

[0128] In the heating mode of the air-conditioning system, the controller is configured to: control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the indoor heat exchanger (4), and the outdoor heat exchanger (3) is connected to the suction side of the compressor (5). Specifically, the E end of the first reversing valve (1) is controlled to be connected to the S end, and the D end of the second reversing valve (2) is controlled to be connected to the C end. The compressor (5) compresses the sucked low-temperature, low-pressure gaseous refrigerant into high-temperature, high-pressure gas and discharges it into the indoor heat exchanger (4) through the second reversing valve (2). In the indoor heat exchanger (4), heat is released and condensed into high-pressure liquid refrigerant. The high-pressure liquid refrigerant enters the outdoor heat exchanger (3) after pressure reduction and throttling by the indoor electronic expansion valve (101). In the outdoor heat exchanger (3), heat is absorbed and evaporated into gaseous refrigerant. The gaseous refrigerant returns to the gas-liquid separator (6) through the first low-pass valve (1) and returns to the suction side of the compressor (5).

[0129] The air-conditioning system starts a defrosting operation in the heating mode when the outdoor heat exchanger (3) is frosted to the point where the defrosting condition is met during the heating process. The controller is configured to: maintain the second reversing valve (2) and switch the first reversing valve (1) so that the exhaust side of the compressor (1) is connected to the outdoor heat exchanger (3). Specifically, the connection state between the D end and the C end of the second reversing valve (2) is maintained unchanged, the heating mode of the indoor heat exchanger (4) is maintained unchanged, that is, the indoor heat exchanger (4) is maintained as an evaporator, and the first reversing valve (1) is switched so that the D end and the E end are connected, thereby connecting the exhaust side of the compressor (5) to the outdoor heat exchanger (3), so that the outdoor heat exchanger (3) is switched from an evaporator to a condenser.

[0130] The specific configuration of the controller for the indoor fan (9), the indoor electronic expansion valve (101), the outdoor electronic expansion valve (102), and the EVB electronic expansion valve (103) can be found in Examples 1 to 3, and will not be described in detail in this example.

[0131] During the defrosting process in the entire heating mode, a large amount of liquid refrigerant will be present in the outdoor heat exchanger (3) and the gas-liquid separator (6), which may cause the exhaust pressure, suction pressure, exhaust temperature, etc. in the air-conditioning system to be lower than the corresponding target values. Therefore, the controller is further configured to determine whether to close the bypass solenoid valve (111) to connect the compressor bypass branch according to the overheating state of the suction of the compressor (5). By closing the bypass solenoid valve (111) to connect the compressor bypass branch, part of the high-temperature and high-pressure refrigerant discharged from the compressor (5) enters the gas-liquid separator (6) to promote the gasification of the liquid refrigerant, increase the refrigerant suction volume of the compressor (5), avoid the compressor (5) suctioning back the liquid and affecting its reliability, and ensure the stable and reliable operation of the unit.

[0132] Example 5

[0133] like Figure 9As shown, the air conditioning system proposed in this embodiment includes:

[0134] An outdoor unit and an indoor unit; wherein the indoor unit includes an indoor heat exchanger (4); and the outdoor unit includes a compressor (5), a first reversing valve (1), an outdoor heat exchanger (3), a subcooler (7), and a gas-liquid separator (6) connected in series.

[0135] The D end of the first reversing valve (1) is connected to the exhaust end of the compressor (5), the E end is connected to the outdoor heat exchanger (3), the S end is connected to the inlet of the gas-liquid separator (6), and the C end is idle.

[0136] The D end of the second reversing valve (2) is connected to the exhaust end of the compressor (5), the C end thereof is connected to the indoor heat exchanger (4), and the S end thereof and the S end of the first reversing valve (1) are both connected to the inlet of the gas-liquid separator (6). The E end of the first reversing valve (1) is connected to the outdoor heat exchanger (3), and the E end is idle.

[0137] The indoor fan (9) is used to operate according to a set air volume to blow hot air during heating or cold air during cooling into the room.

[0138] The indoor electronic expansion valve (101) is connected to the indoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); and is used to throttle and reduce the pressure of the refrigerant condensed from the indoor heat exchanger (4) in the heating mode.

[0139] The outdoor electronic expansion valve (102) is connected to the outdoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); and is used to throttle and reduce the pressure of the refrigerant condensed from the outdoor heat exchanger (3) in the cooling mode.

[0140] The EVB expansion valve (103) is installed on the subcooling branch between the outdoor heat exchanger (3) and the subcooler (7). Typically, in cooling mode, part of the refrigerant condensed from the outdoor heat exchanger (3) enters the subcooler (7) from the e end, exits from the g end after being subcooled, and enters the main refrigeration circuit of the indoor heat exchanger (4). Part of the refrigerant passes through the cold branch and enters the subcooler (7) from the f end, exits from the h end after heat exchange, and returns to the suction side of the compressor (5) after passing through the gas-liquid separator (6).

[0141] The compressor bypass branch is installed between the exhaust side of the compressor (5) and the inlet of the gas-liquid separator (6), and is composed of a bypass solenoid valve (111) and a bypass capillary tube (112) connected in series.

[0142] As mentioned above, the outdoor unit further includes three refrigerant pipelines: a high-pressure gas pipeline (121), a low-pressure gas pipeline (122), and a liquid return pipeline (123); wherein the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122) are both connected to the exhaust side of the compressor (5), and the liquid return pipeline (123) is connected to the suction side of the compressor (5).

[0143] The indoor unit includes: a cold and hot converter (13), connected between the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122) of the outdoor unit and the indoor heat exchanger (4); Figure 10 As shown, the heat-cold converter (13) includes expansion valves (151) and (152) for controlling the on / off of the high-pressure gas pipeline (121), expansion valves (153) and (154) for controlling the on / off of the low-pressure gas pipeline (122), and a bypass capillary (155) between the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122).

[0144] In this embodiment, there are multiple indoor units, and some or all of the indoor units are connected to the heat exchanger (13) via their respective indoor unit air pipes (14). The heat exchanger (13) is connected in parallel between the high-pressure air pipe (121) and the low-pressure air pipe (122) of the outdoor unit and the indoor heat exchanger (4).

[0145] When the air conditioning system operates in the heating mode or defrosts in the heating mode, the controller is configured to: control the expansion valves (151) and (152) on the high-pressure gas pipeline (121) side to open, and the expansion valves (153) and (154) on the low-pressure gas pipeline (122) side to close, so that the indoor unit gas pipe (14) is connected to the high-pressure gas pipeline (121).

[0146] When the air conditioning system operates in cooling mode, the controller is configured to: control the expansion valves (153) and (154) on the low-pressure gas pipeline (122) side to open, and the expansion valves (151) and (152) on the high-pressure gas pipeline (131) side to close, so that the indoor unit gas pipe (14) is connected to the low-pressure gas pipeline (122).

[0147] Based on the air-conditioning system provided in the embodiment of the present invention, combined with the control of the expansion valves on the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122) of the cold-heat converter (13), it is possible to realize the simultaneous operation of cooling and heating of multiple indoor units, and the outdoor heat exchanger (3) can be flexibly switched between cooling mode, heating mode and defrosting in heating mode, and can take into account the application of a two-pipe air-conditioning system and a three-pipe air-conditioning system at the same time, thereby improving the flexibility and scalability of the air-conditioning system.

[0148] The specific configuration of the controller for the indoor fan (9), the indoor electronic expansion valve (101), the outdoor electronic expansion valve (102), the EVB electronic expansion valve (103), the compressor bypass branch, etc., can be referred to in Examples 1 to 4, and will not be described in detail in this embodiment.

[0149] Example 6

[0150] In this embodiment, based on any of the above embodiments, Figure 11As shown, the C end and the S end of the first reversing valve (1) are short-circuited via a first capillary tube (81); and / or the E end and the S end of the second reversing valve (2) are short-circuited via a second capillary tube (82).

[0151] Since the first reversing valve (1) does not need to be reversed regardless of whether it is in the heating process or in the heating defrosting process, refrigerant liquid may accumulate at the idle end of the first reversing valve (1). In order to ensure that the first reversing valve (1) is smoothly operated without being obstructed by liquid refrigerant during the reversing process, a first capillary tube (81) is added between the C end and the S end thereof. The first capillary tube (81) bypasses the accumulated refrigerant to the gas-liquid separator (6), thereby preventing the accumulated refrigerant liquid from obstructing the reversing of the first reversing valve (1). Similarly, in some embodiments of the present invention, since the second reversing valve (2) does not need to be reversed during the refrigeration process, refrigerant liquid may accumulate at the idle end of the second reversing valve (2). In order to ensure that the second reversing valve (2) is smoothly operated without being obstructed by liquid refrigerant during the reversing process, a second capillary tube (82) is added between the E end and the S end thereof. The second capillary tube (82) bypasses the accumulated refrigerant to the gas-liquid separator (6), thereby preventing the accumulated refrigerant liquid from obstructing the reversing of the second reversing valve (2).

[0152] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0153] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. An air conditioning system comprising: An outdoor unit and an indoor unit; wherein the outdoor unit includes an outdoor heat exchanger (3), and the indoor unit includes an indoor heat exchanger (4); It is characterized by further comprising: A first reversing valve (1) is arranged in the outdoor unit and is used to switch the state of the outdoor heat exchanger (3) between the condenser and the evaporator; A second reversing valve (2) is arranged in the outdoor unit and is used to switch the state of the indoor heat exchanger (4) between the condenser and the evaporator; The controller is configured as: When the air conditioning system operates in a heating mode, the first reversing valve (1) and the second reversing valve (2) are controlled so that the outdoor heat exchanger (3) is used as an evaporator and the indoor heat exchanger (4) is used as a condenser; When the air conditioning system is running in the heating mode and needs to be defrosted, the second reversing valve (2) is maintained and the first reversing valve (1) is controlled to be reversed, so that the indoor heat exchanger (4) is maintained as a condenser to perform heating, and the outdoor heat exchanger (3) is switched to perform defrosting as a condenser; the refrigerant after the heat is released by the indoor heat exchanger (4) and the refrigerant after the heat is released by the outdoor heat exchanger (3) are mixed, and after being vaporized by heat exchange, they return to the suction side of the compressor; The outdoor unit is composed of a compressor (5), a first reversing valve (1), an outdoor heat exchanger (3), a subcooler (7) and a gas-liquid separator (6) connected in series; the second reversing valve (2), its D end and the D end of the first reversing valve (1) are both connected to the exhaust end of the compressor (5), its C end is connected to the indoor heat exchanger (4), and its S end and the S end of the first reversing valve (1) are both connected to the inlet of the gas-liquid separator (6); wherein the E end of the first reversing valve (1) is connected to the outdoor heat exchanger (3); the controller is configured to: when the air-conditioning system operates in a heating mode, control the first reversing valve (1) and the second reversing valve (2) so that the exhaust side of the compressor (5) is connected to the indoor heat exchanger (4), and the outdoor heat exchanger (3) is connected to the suction side of the compressor (5); when the air-conditioning system operates in a heating mode and needs to be defrosted, maintain the second reversing valve (2) and switch the first reversing valve (1) so that the exhaust side of the compressor (5) is connected to the outdoor heat exchanger (3); The indoor unit further includes: Indoor fan (9); An indoor electronic expansion valve (101) is connected to the indoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); The controller is configured to: when the air conditioning system is operating in a heating mode and needs to be defrosted, adjust the air volume of the indoor fan (9) and the opening of the indoor electronic expansion valve (101) so that the superheat of the refrigerant condensed from the indoor heat exchanger (4) does not exceed a first preset superheat; The first preset superheat degree satisfies that the refrigerant after condensation from the indoor heat exchanger (4) is in a gaseous state or a gas-liquid two-phase state; The outdoor unit further includes: An outdoor electronic expansion valve (102) is connected to the outdoor side between the indoor heat exchanger (4) and the outdoor heat exchanger (3); The controller is configured to: when the air-conditioning system is running in heating mode and needs to be defrosted, adjust the opening of the outdoor electronic expansion valve (102) to adjust the amount of refrigerant entering the outdoor heat exchanger (3) from the exhaust side of the compressor (5), so that the superheat of the refrigerant condensed from the outdoor heat exchanger (3) and the refrigerant condensed from the indoor heat exchanger (4) after mixing in the supercooler (7) does not exceed a second preset superheat; the second preset superheat satisfies that the mixed refrigerant is in a gaseous state or a gas-liquid two-phase state; wherein the second preset superheat does not exceed the first preset superheat; during heating and defrosting operation, the refrigerant condensed from the outdoor heat exchanger (3) and the indoor heat exchanger (4) are mixed in the supercooler (7), and the high-temperature refrigerant and the low-temperature refrigerant are heat-exchanged to promote gasification and then return to the gas-liquid separator (6), and after gas-liquid separation in the gas-liquid separator (6), the gaseous refrigerant returns to the compressor (5).

2. The air conditioning system according to claim 1, characterized in that The outdoor unit further includes: An EVB expansion valve (103) is installed on the subcooling branch between the outdoor heat exchanger (3) and the subcooler (7); The controller is configured to adjust the opening of the outdoor electronic expansion valve (102) and the opening of the EVB expansion valve (103) according to the defrosting demand when the air-conditioning system is running in the heating mode and needs to be defrosted, so as to adjust the amount of refrigerant entering the outdoor heat exchanger (3).

3. The air conditioning system according to claim 1, characterized in that The outdoor unit further includes: A compressor bypass branch is installed between the exhaust side of the compressor (5) and the inlet of the gas-liquid separator (6), and is composed of a bypass solenoid valve (111) and a bypass capillary tube (112) connected in series; The controller is configured to determine whether to close the bypass solenoid valve (111) to connect the compressor bypass branch according to the overheating state of the suction air of the compressor (5) when the air conditioning system is running in a heating mode and needs to be defrosted.

4. The air conditioning system according to claim 1, characterized in that The outdoor unit further comprises three refrigerant pipelines: a high-pressure gas pipeline (121), a low-pressure gas pipeline (122) and a liquid return pipeline (123); wherein the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122) are both connected to the exhaust side of the compressor (5), and the liquid return pipeline (123) is connected to the suction side of the compressor (5); The indoor unit further includes: The heat exchanger (13) is connected between the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122) of the outdoor unit and the indoor heat exchanger (4); it includes an expansion valve for controlling the on-off of the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122), and a bypass capillary between the high-pressure gas pipeline (121) and the low-pressure gas pipeline (122); The controller is configured to: when the air conditioning system is operating in heating mode or defrosting in heating mode, control the expansion valve on the high-pressure gas pipeline (121) side to open and the expansion valve on the low-pressure gas pipeline (122) side to close, so that the indoor unit gas pipe is connected to the high-pressure gas pipeline (121).

5. The air conditioning system according to claim 1, characterized in that The C end and the S end of the first reversing valve (1) are short-circuited via a first capillary tube (81).

6. The air conditioning system according to claim 1, characterized in that The E end and the S end of the second reversing valve (2) are short-circuited via a second capillary tube (82).

7. The air conditioning system according to claim 1, characterized in that The controller is configured to: When the air conditioning system operates in a heating mode, the E end of the first reversing valve (1) is controlled to be connected to the S end, and the D end of the second reversing valve (2) is controlled to be connected to the C end; When the air conditioning system is running in heating mode and needs to be defrosted, the D end and the C end of the second reversing valve (2) are maintained in communication, and the D end and the E end of the first reversing valve (1) are switched to be in communication.

Images