Air conditioning system and control method thereof

Abstract

The invention relates to the technical field of air conditioners, particularly provides an air conditioning system and a control method thereof, and aims to solve the problem that an existing air conditioner cannot continue heating during defrosting. In order to achieve the purpose, the air conditioning system comprises a first branch, a second branch, a first heat exchanger, an indoor heat exchanger and an outdoor heat exchanger. A first heat exchange branch of the first heat exchanger and the indoor heat exchanger are sequentially arranged on the first branch; the second branch and the first branch are arranged in parallel, a second heat exchange branch of the first heat exchanger is arranged on the second branch, and the first heat exchange branch and the second heat exchange branch can exchange heat; in the defrosting mode, a high-temperature refrigerant is introduced into the second branch, so that the second heat exchange branch heats a refrigerant flowing from the outdoor heat exchanger to the indoor heat exchanger in the first heat exchange branch; and the refrigerant flowing to the indoor heat exchanger is converted into the high-temperature gaseous refrigerant, so that the indoor unit can continue to heat, the heating requirement of a user is met, and the experience feeling of the user is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular provides an air conditioning system and a control method thereof. Background Art

[0002] With the development of society and the economy, air conditioners have become indispensable electrical appliances. In autumn and winter, when outdoor temperatures are low, more and more households are turning to air conditioning for heating, in addition to other methods such as heating. However, in cold climates or low-temperature environments, the outdoor unit of an air conditioner is prone to frost when heating is in operation. During the defrost process, the air conditioner must be shut down and switched from heating mode to defrost mode. During defrost mode, heating stops and resumes after defrosting. When the outdoor unit is prone to frost, the air conditioner frequently enters defrost mode, providing intermittent heating and failing to meet the user's heating needs.

[0003] Therefore, there is an urgent need for an air-conditioning system and a control method thereof to solve the above technical problems. Summary of the Invention

[0004] The present invention aims to solve the above technical problem, that is, to solve the problem that the existing air conditioner cannot continue to heat during defrosting.

[0005] In a first aspect, the present invention provides an air conditioning system comprising a first branch, a second branch, a first heat exchanger, an indoor heat exchanger, and an outdoor heat exchanger;

[0006] The outdoor heat exchanger, the first heat exchange branch of the first heat exchanger and the indoor heat exchanger are sequentially arranged on the first branch;

[0007] The second branch is arranged in parallel with the first branch, the second heat exchange branch of the first heat exchanger is arranged on the second branch, and the first heat exchange branch and the second heat exchange branch can perform heat exchange;

[0008] In the defrost mode, the second branch is fed with high-temperature refrigerant, so that the second heat exchange branch heats the refrigerant in the first heat exchange branch flowing from the outdoor heat exchanger to the indoor heat exchanger.

[0009] In a specific embodiment of the above-mentioned air-conditioning system, a first throttling element is provided on the second branch, and the first throttling element is used to control the flow rate of the refrigerant flowing through the first heat exchange branch to control the heating capacity of the indoor heat exchanger.

[0010] In a specific embodiment of the above-mentioned air-conditioning system, the air-conditioning system also includes a four-way valve, the first interface of the four-way valve is connected to the exhaust end of the compressor, the second interface of the four-way valve is connected to the intake end of the compressor, the third interface of the four-way valve is connected to the side of the outdoor heat exchanger away from the indoor heat exchanger, and the fourth interface of the four-way valve is connected to the side of the indoor heat exchanger away from the outdoor heat exchanger.

[0011] In a specific embodiment of the above air-conditioning system, the air-conditioning system further includes a compressor,

[0012] In heating or defrosting mode, the exhaust end of the compressor is connected to the side of the outdoor heat exchanger away from the indoor heat exchanger, and the suction end is connected to the side of the indoor heat exchanger away from the outdoor heat exchanger;

[0013] The exhaust end of the compressor is connected to the first end of the second branch, and the second end of the second branch is connected to the suction end of the compressor or the first interface.

[0014] In a second aspect, the present invention provides a control method for the air-conditioning system as described above, the control method comprising the following steps:

[0015] The refrigerant flow rate in the second branch is determined according to the operating mode of the air-conditioning system.

[0016] In a specific embodiment of the control method of the air-conditioning system, “determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes:

[0017] In the defrost mode, the first throttling element is opened to allow high-temperature refrigerant to flow through the second branch, so that the second heat exchange branch heats the refrigerant in the first heat exchange branch flowing from the outdoor heat exchanger to the indoor heat exchanger.

[0018] In a specific embodiment of the control method of the air-conditioning system, in the defrost mode, “determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes:

[0019] The opening degree of the first throttling element is determined according to a first target temperature and a first current temperature of the indoor heat exchanger.

[0020] In a specific embodiment of the control method of the air-conditioning system, “determining the opening degree of the first throttling element according to the first target temperature and the first current temperature of the indoor heat exchanger” includes:

[0021] When the first current temperature is lower than the first target temperature minus a first threshold, increasing the opening of the first throttling element;

[0022] When the first current temperature is higher than the first target temperature+a first threshold, the opening degree of the first throttle element is reduced.

[0023] In a specific embodiment of the control method of the air-conditioning system, in the defrost mode, “determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes:

[0024] The opening degree of the first throttling element is determined according to a second target temperature and a second current temperature of the outdoor heat exchanger.

[0025] Preferably, “determining the opening degree of the first throttling element according to the second target temperature and the second current temperature of the outdoor heat exchanger” includes:

[0026] When the second current temperature is lower than the second target temperature minus a second threshold, reducing the opening of the first throttle element;

[0027] When the second current temperature is higher than the second target temperature+a second threshold, increasing the opening of the first throttling element;

[0028] In a specific embodiment of the control method of the air-conditioning system, “determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes:

[0029] In a non-defrost mode, the first throttling element is closed.

[0030] When adopting the above technical solution, the air-conditioning system of the present invention includes a first branch, a second branch, a first heat exchanger, an indoor heat exchanger and an outdoor heat exchanger; the outdoor heat exchanger, the first heat exchange branch of the first heat exchanger and the indoor heat exchanger are sequentially arranged on the first branch; the second branch is arranged in parallel with the first branch, and the second heat exchange branch of the first heat exchanger is arranged on the second branch, and the first heat exchange branch and the second heat exchange branch can perform heat exchange; in the defrost mode, high-temperature refrigerant is introduced into the second branch so that the second heat exchange branch heats the refrigerant in the first heat exchange branch flowing from the outdoor heat exchanger to the indoor heat exchanger; making the refrigerant flowing to the indoor heat exchanger a high-temperature gaseous refrigerant can enable the indoor unit to continue heating, thereby ensuring the user's heating needs and the user's experience.

[0031] In addition, in the defrost mode, the opening of the first throttling element is determined according to the first target temperature and the first current temperature of the indoor heat exchanger and / or according to the second target temperature and the second current temperature of the outdoor heat exchanger; the opening of the first throttling element can be adjusted to an appropriate position, which can meet both the heating demand and the defrosting demand of the indoor unit; and the air-conditioning system can be operated in a better state. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0033] Figure 1 It is a structural schematic diagram of the air-conditioning system provided by the present invention;

[0034] Figure 2 This is a flow chart of the control method of the air-conditioning system provided by the present invention.

[0035] List of reference numerals: 1. compressor; 2. fourth temperature sensor; 3. first pressure sensor; 4. oil separator; 5. second one-way valve; 6. four-way valve; 7. gas pipe stop valve; 8. outdoor heat exchanger; 9. outdoor fan; 11. second throttling element; 12. injection valve; 13. first one-way valve; 14. gas-liquid separator; 15. liquid pipe stop valve; 16. oil return valve; 17. first throttling element; 18. second pressure sensor; 19. second temperature sensor; 20. first heat exchanger; 21. third temperature sensor; 22. indoor heat exchanger; 23. indoor unit throttling device; 24. first temperature sensor. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0037] It should be noted that in the description of the present invention, terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. These terms are used solely for ease of description and are not intended to indicate or imply that the device or component described must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "installed," "disposed," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0039] like Figure 1As shown, this embodiment discloses an air-conditioning system, which includes a first branch, a second branch, a first heat exchanger 20, an indoor heat exchanger 22, an outdoor heat exchanger 8, a compressor 1, an oil separator 4, a four-way valve 6, a first throttling element 17, a second throttling element 11 and a gas-liquid separator 14, etc.

[0040] The outdoor heat exchanger 8, the second throttling element 11, the first heat exchange branch of the first heat exchanger 20 and the indoor heat exchanger 22 are sequentially arranged on the first branch.

[0041] The first interface of the four-way valve 6 is connected to the exhaust end of the compressor 1, the second interface of the four-way valve 6 is connected to the suction end of the compressor 1, the third interface of the four-way valve 6 is connected to the side of the outdoor heat exchanger 8 away from the indoor heat exchanger 22, and the fourth interface of the four-way valve 6 is connected to the side of the indoor heat exchanger 22 away from the outdoor heat exchanger 8.

[0042] A gas pipe shutoff valve 7 (specifically, a solenoid valve or electric ball valve, which can be controlled by the air conditioning system's control module) is installed between the indoor heat exchanger 22 and the four-way valve 6. If a leak occurs in the indoor heat exchanger 22, the gas pipe shutoff valve 7 closes to prevent refrigerant from leaking from the outdoor heat exchanger 8. This also prevents refrigerant from leaking from the indoor heat exchanger 22 if a leak occurs on the outdoor heat exchanger 8 side, thus reducing leakage.

[0043] An indoor throttling element is provided between the indoor heat exchanger 22 and the gas pipe stop valve 7 , which is specifically an electronic expansion valve for adjusting the refrigerant flow of the indoor heat exchanger 22 , thereby controlling the heat exchange capacity of the indoor heat exchanger 22 .

[0044] A liquid pipe shutoff valve 15 (specifically, a solenoid valve or an electric ball valve, which can be controlled by the air conditioning system's control module) is installed between the indoor heat exchanger 22 and the outdoor heat exchanger 8. If a leak occurs in the indoor heat exchanger 22, the liquid pipe shutoff valve 15 closes to prevent refrigerant from leaking from the outdoor heat exchanger 8. This also prevents refrigerant from leaking from the indoor heat exchanger 22 if a leak occurs on the outdoor heat exchanger 8 side, thus minimizing leakage.

[0045] A gas-liquid separator 14 is provided between the suction end and the second interface of the compressor 1. An oil separator 4 is provided between the discharge end and the first interface of the compressor 1, wherein the oil return port of the oil separator 4 is connected to the suction end of the compressor 1, so that the lubricating oil re-enters the compressor 1 for lubrication.

[0046] The second throttling element 11 is specifically an electronic expansion valve, which is used to adjust the refrigerant flow between the indoor heat exchanger 22 and the outdoor heat exchanger 8, thereby controlling the heat exchange capacity of the indoor heat exchanger 22.

[0047] The second branch is arranged in parallel with the first branch, wherein the exhaust end of the compressor 1 is connected to the first end of the second branch, and the second end of the second branch is connected to the first interface, so that the refrigerant after heat exchange can flow to the outdoor heat exchanger 8 or the indoor heat exchanger 22 for continued use.

[0048] Regarding the connection position of the second end of the second branch, it should be noted that although in this embodiment, it is connected to the first interface, this is not a limitation of the present invention. Without departing from the principles of the present invention, in other embodiments, those skilled in the art may choose to connect the second end of the second branch to the suction end of the compressor 1, that is, to the second interface of the four-way valve 6. This does not deviate from the basic principles of the present invention and falls within the scope of protection of the present invention.

[0049] The second heat exchange branch of the first heat exchanger 20 is disposed on the second branch. The first and second heat exchange branches are capable of heat exchange, allowing the second heat exchange branch to heat the refrigerant within the first heat exchange branch. Specifically, the first heat exchanger 20 is a plate heat exchanger with high heat exchange efficiency. In defrost mode, high-temperature refrigerant flows into the second branch, allowing the second heat exchange branch to heat the refrigerant in the first heat exchange branch, flowing from the outdoor heat exchanger 8 to the indoor heat exchanger 22. The plate heat exchanger can effectively heat the refrigerant flowing to the indoor heat exchanger 22.

[0050] A first throttling element 17 is provided on the second branch. The first throttling element 17 is used to control the flow of refrigerant flowing through the first heat exchange branch, thereby controlling the heating capacity of the indoor heat exchanger 22. Specifically, the first throttling element 17 is an electronic expansion valve, which is specifically used to control the heat exchange capacity of the second heat exchange branch.

[0051] A first one-way valve 13 is provided on the second branch, which is configured to only allow refrigerant to flow from the exhaust port of the compressor 1 to the second heat exchange branch, and then to the first interface of the four-way valve 6. The first one-way valve 13 is provided on the side of the heat exchanger away from the first throttling element 17. In addition, a first temperature sensor 24 is provided on the inlet side of the second heat exchange branch for detecting the temperature of the refrigerant flowing to the second heat exchange branch. In order to reduce the pressure of the first throttling element 17, a first control valve, specifically a solenoid valve, can be provided on the second branch. When refrigerant is required to flow through the second branch, the first control valve is opened to the maximum opening, and then the flow rate is adjusted by the first throttling element 17.

[0052] A second temperature sensor 19 and a third temperature sensor 21 are respectively provided at the inlet and outlet of the first heat exchange branch for detecting the refrigerant temperature at the inlet and outlet of the first heat exchange branch.

[0053] A fourth temperature sensor 2 and a first pressure sensor 3 are provided at the exhaust port of the compressor 1 to detect the exhaust temperature and pressure of the compressor 1. A second one-way valve 5 is provided between the oil separator 4 and the first interface of the four-way valve 6. The second one-way valve 5 only allows the refrigerant to flow from the oil separator 4 to the first interface.

[0054] A fifth temperature sensor is provided on the outdoor heat exchanger 8 for detecting the temperature of the outdoor heat exchanger 8. Specifically, the fifth temperature sensor is provided at the heat exchange coil of the outdoor heat exchanger 8 to detect the temperature of the heat exchange coil.

[0055] A sixth temperature sensor is provided on the indoor heat exchanger 22 for detecting the temperature of the indoor heat exchanger 22. Specifically, the sixth temperature sensor is provided at the heat exchange coil of the indoor heat exchanger 22 to detect the temperature of the heat exchange coil.

[0056] A second pressure sensor 18 is provided between the second interface and the gas-liquid separator 14 for detecting the low pressure.

[0057] The second interface and the first branch are connected via a third branch. The connection point between the third branch and the first branch is between the second throttling element 11 and the first heat exchange branch. An injection valve 12 is provided on the third branch.

[0058] In the heating mode, the first interface and the fourth interface of the four-way valve 6 are connected, and the second interface and the third interface are connected; the high-temperature and high-pressure refrigerant flowing out of the compressor 1 flows to the indoor heat exchanger 22 through the first interface and the fourth interface of the four-way valve 6, releases heat in the indoor heat exchanger 22 (to heat the indoor room), becomes liquid refrigerant, and then flows to the outdoor heat exchanger 8. After the outdoor heat exchanger 8 absorbs heat, it flows back to the compressor 1 through the second interface and the third interface of the four-way valve 6 again.

[0059] In the cooling mode, the first interface and the third interface of the four-way valve 6 are connected, and the second interface and the fourth interface are connected; the high-temperature and high-pressure refrigerant flowing out of the compressor 1 flows to the outdoor heat exchanger 8 through the first interface and the third interface of the four-way valve 6, releases heat in the outdoor heat exchanger 8, becomes liquid refrigerant, and then flows to the indoor heat exchanger 22. After the indoor heat exchanger 22 absorbs heat (to cool the room), it flows back to the compressor 1 through the second interface and the fourth interface again.

[0060] In the defrost mode, the first interface and the third interface of the four-way valve 6 are connected, and the second interface and the fourth interface are connected; the high-temperature and high-pressure refrigerant flowing out of the compressor 1 flows to the outdoor heat exchanger 8 through the first interface and the third interface of the four-way valve 6, releases heat in the outdoor heat exchanger 8 (defrosts the outdoor heat exchanger 8), becomes liquid refrigerant, and then flows to the first heat exchange branch of the first heat exchanger 20, and then flows to the indoor heat exchanger 22. After the indoor heat exchanger 22 releases heat (to heat the room), it flows back to the compressor 1 again through the second interface and the fourth interface; and the first throttling element 17 is opened to make the high-temperature and high-pressure refrigerant flow to the second heat exchange branch of the first heat exchanger 20 to heat the refrigerant in the first heat exchange branch, so that the refrigerant flowing to the indoor heat exchanger 22 is gaseous refrigerant, so that the indoor heat exchanger 22 can release heat to heat the room.

[0061] The air conditioning system further includes a control module, which is configured to execute a control method for the air conditioning system, the control method comprising the following steps:

[0062] The refrigerant flow rate in the second branch is determined according to the operating mode of the air conditioning system.

[0063] Specifically, “determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes:

[0064] In defrost mode, high-temperature refrigerant flows through the second branch, allowing the second heat exchange branch to heat the refrigerant in the first heat exchange branch, flowing from the outdoor heat exchanger 8 to the indoor heat exchanger 22. Specifically, the first throttle element 17 is opened to allow refrigerant to flow through the second branch. After the defrost mode is activated, the first throttle element 17 is first opened to a preset opening. After a period of operation, the opening degree of the first throttle element 17 is determined based on the first target temperature and first current temperature of the indoor heat exchanger 22, or based on the second target temperature and second current temperature of the outdoor heat exchanger 8.

[0065] In the defrost mode, "determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system" specifically includes:

[0066] The opening degree of the first throttle element 17 is determined according to the first target temperature and the first current temperature of the indoor heat exchanger 22 .

[0067] Specifically, “determining the opening degree of the first throttling element 17 according to the first target temperature and the first current temperature of the indoor heat exchanger 22” includes:

[0068] When the first current temperature is lower than the first target temperature - the first threshold value, the opening of the first throttling element 17 is increased; wherein the first threshold value is a natural value, and setting the first threshold value can avoid frequent adjustment of the first throttling element 17. When the first current temperature is lower than the first target temperature - the first threshold value, the heating capacity of the indoor heat exchanger 22 is weak, and it cannot ensure that the indoor temperature reaches the set temperature, which will affect the user experience. Increasing the opening of the first throttling element 17 can increase the refrigerant flowing to the second heat exchange branch, enhance the heat exchange capacity of the first heat exchanger 20, increase the temperature of the refrigerant in the first heat exchange branch, and increase the temperature of the refrigerant flowing to the indoor heat exchanger 22; increase the temperature of the indoor heat exchanger 22 to make it closer to the first target temperature; ensure the heating efficiency of the indoor heat exchanger 22, and thus ensure the indoor temperature.

[0069] When the first current temperature is higher than the first target temperature + the first threshold, the opening of the first throttling element 17 is reduced. When the first current temperature is higher than the first target temperature + the first threshold, the heating capacity of the indoor heat exchanger 22 is relatively strong, and the indoor temperature will exceed the set temperature, affecting the user experience. Reducing the opening of the first throttling element 17 can reduce the refrigerant flowing to the second heat exchange branch, weakening the heat exchange capacity of the first heat exchanger 20, lowering the temperature of the refrigerant in the first heat exchange branch, and lowering the temperature of the refrigerant flowing to the indoor heat exchanger 22; reducing the temperature of the indoor heat exchanger 22, making it closer to the first target temperature, thereby ensuring the indoor temperature.

[0070] “Determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes:

[0071] The opening degree of the first throttle element 17 is determined according to the second target temperature and the second current temperature of the outdoor heat exchanger 8 .

[0072] Specifically, “determining the opening degree of the first throttling element 17 according to the second target temperature and the second current temperature of the outdoor heat exchanger 8” includes:

[0073] When the second current temperature is lower than the second target temperature minus the second threshold, the opening of the first throttling element 17 is reduced; the second threshold is a natural value, and setting the second threshold can avoid frequent adjustment of the first throttling element 17. When the second current temperature is lower than the second target temperature minus the second threshold, the defrosting capacity of the outdoor heat exchanger 8 is relatively weak, and rapid defrosting of the outdoor heat exchanger 8 cannot be guaranteed. Reducing the opening of the first throttling element 17 can reduce the amount of refrigerant flowing to the second heat exchange branch, thereby increasing the amount of refrigerant flowing to the outdoor heat exchanger 8, enhancing the heat exchange capacity of the outdoor heat exchanger 8, and enabling the frost on the outdoor heat exchanger 8 to be quickly removed.

[0074] When the second current temperature is higher than the second target temperature + the second threshold, the opening of the first throttling element 17 is increased; when the second current temperature is higher than the second target temperature + the second threshold, the strong defrosting capacity of the outdoor heat exchanger 8 will cause unnecessary waste, and the outdoor heat exchanger 8 will emit more heat and cannot guarantee the normal heating of the subsequent indoor heat exchanger 22. Increasing the opening of the first throttling element 17 can increase the refrigerant flowing to the second heat exchange branch, thereby reducing the amount of refrigerant flowing to the outdoor heat exchanger 8, while enhancing the heat exchange capacity of the first heat exchanger 20, increasing the temperature of the refrigerant in the first heat exchange branch, and increasing the temperature of the refrigerant flowing to the indoor heat exchanger 22; increasing the temperature of the indoor heat exchanger 22 to make it closer to the first target temperature; ensuring the heating efficiency of the indoor heat exchanger 22, and thus ensuring the indoor temperature.

[0075] Among them, “determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” also includes:

[0076] In the non-defrosting mode, the first throttling element 17 is closed, so that no refrigerant flows in the second branch, and the refrigerant flows normally through the first branch to perform cooling or heating.

[0077] like Figure 2 As shown, the control method of the air-conditioning system specifically includes the following steps:

[0078] S1. Obtaining the working mode of the air conditioning system;

[0079] S2. Determine whether the working mode is the defrost mode. If yes, proceed to step S3; if not, proceed to step S1 again after a preset time.

[0080] S3, opening the first throttling element 17 to allow the refrigerant to flow into the second branch;

[0081] S4, obtaining a first target temperature and a first current temperature of the indoor heat exchanger 22; then proceeding to step S5;

[0082] S5. Determine whether the first current temperature is lower than the first target temperature minus the first threshold; if so, increase the opening of the first throttling element 17 and proceed to step S7 after a preset time; if not, proceed to step S6;

[0083] S6. Determine whether the first current temperature is higher than the first target temperature + the first threshold; if so, reduce the opening of the first throttle element 17 and proceed to step S7 after a preset time; if not, proceed to step S7 after a preset time;

[0084] S7, obtaining the second target temperature and the second current temperature of the outdoor heat exchanger 8, and then proceeding to step S8;

[0085] S8, determining whether the second current temperature is lower than the second target temperature minus the second threshold; if so, reducing the opening of the first throttle element 17, and then proceeding to step S4; if not, proceeding to step S9;

[0086] S9. Determine whether the second current temperature is higher than the second target temperature + the second threshold. If yes, increase the opening of the first throttling element 17 and then proceed to step S4; if no, proceed to step S4.

[0087] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. An air conditioning system, characterized in that: It includes a first branch, a second branch, a first heat exchanger (20), an indoor heat exchanger (22) and an outdoor heat exchanger (8); The outdoor heat exchanger (8), the first heat exchange branch of the first heat exchanger (20), and the indoor heat exchanger (22) are sequentially arranged on the first branch; The second branch is arranged in parallel with the first branch, the second heat exchange branch of the first heat exchanger (20) is arranged on the second branch, and the first heat exchange branch and the second heat exchange branch are capable of heat exchange; In the defrost mode, a high-temperature refrigerant is introduced into the second branch so that the second heat exchange branch heats the refrigerant in the first heat exchange branch flowing from the outdoor heat exchanger (8) to the indoor heat exchanger (22).

2. The air conditioning system according to claim 1, characterized in that A first throttling element (17) is provided on the second branch, and the first throttling element (17) is used to control the flow of the refrigerant flowing through the first heat exchange branch to control the heating capacity of the indoor heat exchanger (22).

3. The air conditioning system according to claim 2, characterized in that The air-conditioning system further comprises a four-way valve (6), a first interface of the four-way valve (6) being connected to the exhaust end of the compressor (1), a second interface of the four-way valve (6) being connected to the intake end of the compressor (1), a third interface of the four-way valve (6) being connected to a side of the outdoor heat exchanger (8) away from the indoor heat exchanger (22), and a fourth interface of the four-way valve (6) being connected to a side of the indoor heat exchanger (22) away from the outdoor heat exchanger (8).

4. The air conditioning system according to claim 3, characterized in that The air conditioning system further comprises a compressor (1); In heating or defrosting mode, the exhaust end of the compressor (1) is connected to the side of the outdoor heat exchanger (8) away from the indoor heat exchanger (22), and the suction end is connected to the side of the indoor heat exchanger (22) away from the outdoor heat exchanger (8); The exhaust end of the compressor (1) is connected to the first end of the second branch, and the second end of the second branch is connected to the intake end of the compressor (1) or the first interface.

5. A method for controlling an air conditioning system according to any one of claims 2 to 4, characterized in that: The control method comprises the following steps: The refrigerant flow rate in the second branch is determined according to the operating mode of the air-conditioning system.

6. The control method of the air conditioning system according to claim 5, characterized in that: “Determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes: In the defrost mode, the first throttling element (17) is opened to allow high-temperature refrigerant to flow through the second branch, so that the second heat exchange branch heats the refrigerant in the first heat exchange branch flowing from the outdoor heat exchanger (8) to the indoor heat exchanger (22).

7. The control method of the air conditioning system according to claim 6, characterized in that: In the defrost mode, “determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes: The opening degree of the first throttling element (17) is determined according to a first target temperature and a first current temperature of the indoor heat exchanger (22).

8. The control method of the air conditioning system according to claim 7, characterized in that: “Determining the opening degree of the first throttling element (17) based on the first target temperature and the first current temperature of the indoor heat exchanger (22)” includes: When the first current temperature is lower than the first target temperature minus a first threshold, increasing the opening of the first throttling element (17); When the first current temperature is higher than the first target temperature+a first threshold, the opening degree of the first throttling element (17) is reduced.

9. The control method of the air conditioning system according to claim 6, characterized in that: In the defrost mode, “determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes: The opening degree of the first throttling element (17) is determined according to the second target temperature and the second current temperature of the outdoor heat exchanger (8). Preferably, “determining the opening degree of the first throttling element (17) according to the second target temperature and the second current temperature of the outdoor heat exchanger (8)” includes: When the second current temperature is lower than the second target temperature minus a second threshold, reducing the opening of the first throttling element (17); When the second current temperature is higher than the second target temperature+a second threshold, the opening degree of the first throttling element (17) is increased.

10. The control method of the air conditioning system according to claim 5, characterized in that: “Determining the refrigerant flow rate in the second branch according to the operating mode of the air-conditioning system” includes: In non-defrosting mode, the first throttling element (17) is closed.

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