Indoor heat exchanger assembly, multi-split air conditioning system and control method thereof

Abstract

The present invention provides an indoor heat exchanger assembly, a multi-split air conditioning system and a control method thereof, wherein the indoor heat exchanger assembly comprises a heat exchanger body, the heat exchanger body comprises a heat exchange core and an air pipe and a liquid pipe connected to a heat exchange pipe in the heat exchange core, an indoor electronic expansion valve is arranged on the liquid pipe, and a refrigerant bypass pipe is also included, the first end of the refrigerant bypass pipe is connected to the liquid pipe on the side of the indoor electronic expansion valve away from the heat exchange core, the second end of the refrigerant bypass pipe is connected to the air pipe, and a bypass valve is arranged on the refrigerant bypass pipe. According to the present invention, in the heating standby / off mode, by controlling the circulation of the refrigerant bypass pipe and controlling the indoor electronic expansion valve to close, there is no need to control the indoor electronic expansion valve to maintain a certain opening as in the prior art, effectively avoiding the phenomenon of indoor sharp noise caused by the impact of medium and high pressure refrigerant on the valve core at the indoor electronic expansion valve, thereby improving the user experience.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioning, and in particular relates to an indoor heat exchanger component, a multi-split air conditioning system and a control method thereof. Background Art

[0002] At present, the types of multi-split indoor units are increasing and their functions are becoming more and more complete, but some common problems have not been successfully solved. For example, in the heating mode, a large amount of lubricating oil and refrigerant will accumulate in the evaporator and connecting pipes of the standby and shutdown indoor units. In order to allow these lubricating oils to effectively participate in the system circulation, the industry's conventional practice is to keep the electronic expansion valve of the standby and shutdown indoor units at a relatively small opening (generally less than 70pls) and bypass the refrigerant into the system. However, when the electronic expansion valve of the indoor unit is at a small opening, the medium and high pressure refrigerant impacts the electronic expansion valve (valve core) of the indoor unit, which can easily cause sharp noise and affect the user experience. In addition, when the unit is performing defrosting, a large amount of refrigerant flows through the indoor unit, resulting in large fluctuations in indoor temperature; when heating at low temperatures, the compressor is difficult to start, and it is difficult to increase the compressor exhaust temperature in a short period of time. Summary of the invention

[0003] Therefore, the present invention provides an indoor heat exchanger assembly, a multi-split air-conditioning system and a control method thereof, which can overcome the shortcomings of the prior art in which the corresponding indoor electronic expansion valve is kept at a small opening to prevent the accumulation of lubricating oil and refrigerant in the indoor heat exchanger when the multi-split air-conditioning system is in standby or shutdown, causing sharp noise in the room and reducing the user experience.

[0004] In order to solve the above problems, the present invention provides an indoor heat exchanger assembly, including a heat exchanger body, the heat exchanger body including a heat exchange core and a gas pipe and a liquid pipe connected to the heat exchange pipe in the heat exchange core, the liquid pipe is provided with an indoor electronic expansion valve, and also includes a refrigerant bypass pipe, the first end of the refrigerant bypass pipe is connected to the liquid pipe on the side of the indoor electronic expansion valve away from the heat exchange core, the second end of the refrigerant bypass pipe is connected to the gas pipe, and the refrigerant bypass pipe is provided with a bypass valve.

[0005] In some embodiments, the bypass valve is an electric ball valve.

[0006] In some embodiments, a bypass throttling element is provided on the refrigerant bypass pipe, and the bypass throttling element is located on a side of the bypass valve close to the gas pipe.

[0007] In some embodiments, the bypass throttling element is a capillary tube.

[0008] In some embodiments, a gas pipe stop valve is provided on the gas pipe, and the second end of the refrigerant bypass pipe is connected to a side of the gas pipe stop valve away from the heat exchange core.

[0009] In some embodiments, the gas pipe is connected to the heat exchange tubes in the heat exchange core through an air collecting pipe; and / or the liquid pipe is connected to the heat exchange tubes in the heat exchange core through a flow divider.

[0010] The present invention also provides a multi-split air conditioning system, comprising a plurality of indoor units, each of the indoor units comprising the indoor heat exchanger assembly described above.

[0011] The present invention also provides a control method for a multi-split air conditioning system, which is used to control the multi-split air conditioning system, and comprises the following steps:

[0012] Obtain the operating mode of the target indoor unit in the multi-split air conditioning system;

[0013] The opening and closing of an indoor electronic expansion valve and a bypass valve of the target indoor unit are controlled according to the acquired operation mode.

[0014] In some embodiments,

[0015] When the operation mode is one of the heating standby / off mode and the ultra-low temperature heating start mode, the indoor electronic expansion valve is controlled to be closed and the bypass valve is controlled to be opened, so that the refrigerant discharged from the compressor flows into the liquid pipe through the refrigerant bypass pipe; or

[0016] When the operation mode is the special indoor defrosting mode, the indoor electronic expansion valve is controlled to be closed and the bypass valve is controlled to be opened, so that the refrigerant discharged from the outdoor heat exchanger flows into the gas pipe through the refrigerant bypass pipe; or

[0017] When the operation mode is the high-temperature oil return mode, the electronic expansion valve and the bypass valve of the indoor unit are controlled to be opened, so that the refrigerant discharged from the compressor flows into the gas pipe through the refrigerant bypass pipe and the heat exchange core; or

[0018] When the operation mode is the normal cooling mode, the indoor electronic expansion valve is controlled to open and the bypass valve is controlled to close, so that the refrigerant discharged from the outdoor heat exchanger flows from the heat exchange core into the gas pipe; or

[0019] When the operation mode is a normal heating mode, the indoor electronic expansion valve is controlled to open and the bypass valve is controlled to close, so that the refrigerant discharged from the compressor flows from the heat exchange core into the liquid pipe.

[0020] In some embodiments, when the operating mode is one of a heating standby mode, a shutdown mode, an ultra-low temperature heating start-up mode, and a special indoor defrosting mode, it also includes controlling the indoor electronic expansion valve to open after a first preset time and to close again after a second preset time.

[0021] In some embodiments, when the indoor heat exchanger assembly further includes an air pipe stop valve, when the operation mode is a heating standby / off mode, an ultra-low temperature heating start-up mode, or a special indoor unit defrosting mode, the air pipe stop valve is controlled to be closed; or,

[0022] When the operation mode is a high-temperature oil return mode, a normal cooling mode or a normal heating mode, the gas pipe stop valve is controlled to open.

[0023] The present invention provides an indoor heat exchanger assembly, a multi-split air-conditioning system and a control method thereof. The refrigerant bypass pipe is added between the liquid pipe and the gas pipe on the side of the indoor electronic expansion valve away from the heat exchange core, and the bypass valve on the refrigerant bypass pipe is controlled to achieve flow control of the refrigerant in different operating modes of the air-conditioning system. In particular, in the heating standby / shutdown mode, the flow of the refrigerant bypass pipe is controlled and the indoor electronic expansion valve is controlled to be closed. There is no need to control the indoor electronic expansion valve to maintain a certain opening as in the prior art, which effectively avoids the occurrence of sharp indoor noise caused by the impact of medium and high pressure refrigerant on the valve core at the indoor electronic expansion valve, thereby improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of an indoor heat exchanger assembly of an embodiment of the present invention, which shows the refrigerant flow direction when the air-conditioning system is in a heating standby / off mode and an ultra-low temperature heating start-up mode;

[0025] Figure 2 is a schematic structural diagram of an indoor heat exchanger assembly according to an embodiment of the present invention, which shows the refrigerant flow direction when the air-conditioning system is in a special indoor unit defrosting mode;

[0026] Figure 3 The schematic diagram of the structure of the indoor heat exchanger assembly of the embodiment of the present invention shows the refrigerant flow direction of the air-conditioning system in the normal heating mode.

[0027] Figure 4 is a schematic structural diagram of an indoor heat exchanger assembly according to an embodiment of the present invention, which shows the refrigerant flow direction when the air-conditioning system is in a normal cooling mode;

[0028] Figure 5 is a schematic structural diagram of an indoor heat exchanger assembly according to an embodiment of the present invention, which shows the refrigerant flow direction when the air-conditioning system is in a high-temperature oil return mode;

[0029] Figure 6 The structure diagram of a multi-split air conditioning system according to another embodiment of the present invention is shown, wherein only one indoor unit is shown, and the flow direction of the refrigerant is shown by taking the cooling mode as an example;

[0030] Figure 7 Another structural schematic diagram of the indoor heat exchanger assembly according to an embodiment of the present invention.

[0031] The reference numerals are:

[0032] 1. Heat exchanger body; 11. Heat exchange core; 12. Gas pipe; 121. Gas pipe stop valve; 122. Gas collecting pipe; 13. Liquid pipe; 131. Diverter; 132. Capillary branch; 14. Indoor electronic expansion valve; 151. Gas pipe temperature sensor; 152. Liquid pipe temperature sensor; 153. Ambient temperature sensor; 2. Refrigerant bypass pipe; 21. Bypass valve; 22. Bypass throttling element; 100. Compressor; 101. Four-way valve; 102. Outdoor heat exchanger; 103. Gas-liquid separator; 104. Heating electronic expansion valve. DETAILED DESCRIPTION

[0033] See also Figures 1 to 7 As shown, according to an embodiment of the present invention, an indoor heat exchanger assembly is provided, including a heat exchanger body 1, wherein the heat exchanger body 1 includes a heat exchange core 11 and an air pipe 12 and a liquid pipe 13 connected to the heat exchange pipe in the heat exchange core 11, wherein the liquid pipe 13 is provided with an indoor electronic expansion valve 14, and the indoor electronic expansion valve 14 can cut off or flow the refrigerant entering the heat exchange core 11 by adjusting its opening, and further includes a refrigerant bypass pipe 2, wherein a first end of the refrigerant bypass pipe 2 is connected to the liquid pipe 13 on a side of the indoor electronic expansion valve 14 away from the heat exchange core 11, and a second end of the refrigerant bypass pipe 2 is connected to the air pipe 12, and a bypass valve 21 is provided on the refrigerant bypass pipe 2. In this technical solution, the refrigerant bypass pipe 2 is additionally provided between the liquid pipe 13 and the gas pipe 12 on the side of the indoor electronic expansion valve 14 away from the heat exchange core 11, and the bypass valve 21 on the refrigerant bypass pipe 2 is controlled to realize the flow control of the refrigerant in different operation modes of the air-conditioning system, especially in the heating standby / shutdown mode, by controlling the circulation of the refrigerant bypass pipe 2 (specifically, it can be intermittent circulation) and controlling the indoor electronic expansion valve 14 to close, thereby eliminating the need to control the indoor electronic expansion valve 14 to maintain a certain opening as in the prior art, effectively avoiding the occurrence of sharp indoor noise caused by the impact of medium and high pressure refrigerant on the valve core at the indoor electronic expansion valve 14, thereby improving the user experience. It should be noted that when the indoor heat exchanger assembly is applied to a multi-split air-conditioning system, it can further bring other beneficial effects that match the corresponding operating mode, such as: reducing indoor temperature fluctuations during defrosting and improving heating comfort; under low-temperature heating, the compressor quickly establishes exhaust superheat, and will not pass through the indoor unit heat exchanger at startup to improve reliability and comfort; return oil at high temperature, return liquid through a bypass branch, and speed up the oil return speed, etc., which will be further elaborated in conjunction with the specific operating mode later.

[0034] The refrigerant bypass pipe 2 may be integrated with the heat exchange core 11 or may be a separate body.

[0035] In some embodiments, the bypass valve 21 is an electric ball valve. The structure of the electric ball valve is different from that of the electronic expansion valve. The electric ball valve is "straight in and straight out", while most expansion valves are "horizontal in and vertical out". Therefore, the electric ball valve can guide the flow more smoothly without loud noise or sharp sound, further reducing the operating noise of the indoor unit in the heating standby / shutdown mode.

[0036] In some embodiments, the refrigerant bypass pipe 2 is provided with a bypass throttling element 22, and the bypass throttling element 22 is located on the side of the bypass valve 21 close to the gas pipe 12. By arranging the bypass throttling element 22 on the high-pressure side of the bypass valve 21, the corresponding refrigerant (gaseous state) can be throttled and depressurized, thereby reducing damage caused by impact on the bypass valve 21 and improving the service life of the bypass valve 21. The bypass throttling element 22 can be an electronic expansion valve or a capillary tube, and is preferably a capillary tube based on the consideration of minimizing noise.

[0037] In some embodiments, Figure 7 As shown, the gas pipe 12 is provided with a gas pipe stop valve 121, and the second end of the refrigerant bypass pipe 2 is connected to the side of the gas pipe stop valve 121 away from the heat exchange core 11, so that the accumulation of lubricating oil and refrigerant in the corresponding indoor heat exchanger under certain working conditions (such as heating standby / off mode) can be effectively prevented by controlling the closing (i.e., cutting off) of the gas pipe stop valve 121. It can be understood that the gas pipe 12 is connected to the heat exchange tube in the heat exchange core 11 through the gas collecting pipe 122; and / or the liquid pipe 13 is connected to the heat exchange tube in the heat exchange core 11 through the diverter 131, so that the refrigerant is more evenly distributed in the heat exchange core 11, thereby improving the heat exchange efficiency.

[0038] like Figure 6 As shown, according to an embodiment of the present invention, there is also provided a multi-split air conditioning system, comprising a plurality of indoor units, each of the indoor units comprising the indoor heat exchanger assembly described above.

[0039] According to an embodiment of the present invention, a control method for a multi-split air conditioning system is also provided, which is used to control the multi-split air conditioning system, and comprises the following steps:

[0040] Obtaining the operation mode of a target indoor unit in the multi-split air conditioning system, wherein the target indoor unit is the indoor unit that needs to run the operation mode, which may be multiple or one;

[0041] The opening and closing of the indoor electronic expansion valve 14 and the bypass valve 21 of the target indoor unit are controlled according to the acquired operation mode.

[0042] For details, see Figure 1 As shown, when the operating mode is one of the heating standby / shutdown mode and the ultra-low temperature heating start-up mode, the indoor electronic expansion valve 14 is controlled to be closed and the bypass valve 21 is opened, so that the refrigerant discharged from the compressor flows into the liquid pipe 13 through the refrigerant bypass pipe 2. Specifically, in the heating standby / shutdown mode, the refrigerant does not need to flow through the heat exchange core 11 because there is no heat exchange demand. Therefore, the indoor electronic expansion valve 14 can be closed to prevent the noise of the valve core being impacted by the refrigerant. For the ultra-low temperature heating start-up mode, at ultra-low temperature, the system receives a start-up command. At this time, the refrigerant viscosity is large and the compressor exhaust temperature rises slowly. At this time, only the bypass valve 21 is opened, which not only ensures the circulation of the refrigerant, but also reduces the large amount of heat released by the refrigerant in the heat exchanger, and can quickly increase the exhaust temperature, thereby establishing the exhaust superheat. The ultra-low temperature judgment condition is: when the ambient temperature sensor detects a temperature lower than T1 (T1 is generally less than 0°C, for example -15°C), and it can be understood that when the indoor air pipe temperature sensor detects a temperature greater than T2 (T2 is recommended to be greater than 30°C), the control system should restore the normal heating mode, that is, switch to the control logic under the normal heating mode.

[0043] See also Figure 2 As shown, when the operation mode is the special indoor unit defrosting mode, the indoor unit electronic expansion valve 14 is controlled to be closed and the bypass valve 21 is opened, so that the refrigerant discharged from the outdoor unit heat exchanger flows into the air pipe 12 from the refrigerant bypass pipe 2. Specifically, the special indoor unit refers to an indoor unit with a higher priority, such as an indoor unit in a VIP room or an indoor unit with heating shutdown (the shutdown user does not want to be affected). When these indoor units are defrosting in the air-conditioning system (outdoor unit defrosting), only the refrigerant bypass pipe 2 is opened, which ensures the rapid circulation of the refrigerant and does not cause the room temperature to drop rapidly due to the refrigerant absorbing heat in the indoor unit heat exchanger. In the existing practice, most of the indoor unit electronic expansion valves are fully opened, and the refrigerant flows through the entire heat exchanger. The entire heat exchanger absorbs indoor heat, causing the indoor ambient temperature to drop rapidly. Therefore, the method of the present invention can advantageously reduce the temperature fluctuation of the space where the target indoor unit is located.

[0044] See also Figure 5As shown, when the operating mode is the high-temperature oil return mode, the indoor electronic expansion valve 14 and the bypass valve 21 are controlled to be opened so that the refrigerant discharged from the compressor flows into the air pipe 12 from the refrigerant bypass pipe 2 and the heat exchange core 11. Specifically, the compressor generally operates at the (highest) frequency during oil return. At high temperatures, the system high pressure (pressure) is relatively large during normal operation. At this time, boosting the compressor frequency will often lead to high-pressure protection or forced frequency reduction for oil return and low oil return efficiency. However, through the present invention, opening the refrigerant bypass pipe 2 at this time can speed up the liquid return, quickly transfer the mixed refrigerant and lubricating oil liquid to the air pipe, and then return to the compressor side, effectively preventing high-pressure protection or forced frequency reduction for oil return and low oil return efficiency caused by high-temperature oil return.

[0045] See also Figure 4 As shown, when the operation mode is the normal cooling mode, the indoor electronic expansion valve 14 is controlled to open and the bypass valve 21 is closed, so that the refrigerant discharged from the outdoor heat exchanger flows from the heat exchange core 11 into the air pipe 12; or, see Figure 3 As shown, when the operation mode is the normal heating mode, the indoor electronic expansion valve 14 is controlled to open and the bypass valve 21 is controlled to close, so that the refrigerant discharged from the compressor flows from the heat exchange core 11 into the liquid pipe 13 .

[0046] In order to prevent the slow seepage and accumulation of refrigerant and lubricating oil in the heat exchange core 11 of the target indoor unit in some modes, when the operating mode is one of the heating standby mode, the shutdown mode, the ultra-low temperature heating start-up mode, and the special indoor unit defrosting mode, it also includes controlling the indoor unit electronic expansion valve 14 to open at an interval of a first preset time and close again after a second preset time. For example, the indoor unit electronic expansion valve 250PLS is opened every 20 minutes, and is opened for 1 minute before being closed.

[0047] When the indoor heat exchanger assembly also includes an air pipe stop valve 121, when the operating mode is a heating standby / shutdown mode, an ultra-low temperature heating start-up mode or a special indoor unit defrosting mode, the air pipe stop valve 121 is controlled to be closed. At this time, since the air pipe stop valve 121 is closed, the accumulation of refrigerant and lubricating oil in the heat exchange core 11 can be completely prevented in these operating modes; or, when the operating mode is a high-temperature oil return mode, a normal cooling mode or a normal heating mode, the air pipe stop valve 121 is controlled to be open.

[0048] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0049] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A control method for a multi-split air conditioning system, characterized in that: Used to control a multi-split air conditioning system, the multi-split air conditioning system comprising a plurality of indoor units, each of the indoor units comprising an indoor heat exchanger assembly, the indoor heat exchanger assembly comprising a heat exchanger body (1), the heat exchanger body (1) comprising a heat exchange core (11) and an air pipe (12) and a liquid pipe (13) connected to a heat exchange pipe in the heat exchange core (11), the liquid pipe (13) being provided with an indoor unit electronic expansion valve (14), and further comprising a refrigerant bypass pipe (2), the first end of the refrigerant bypass pipe (2) being connected to the liquid pipe (13) on a side of the indoor unit electronic expansion valve (14) away from the heat exchange core (11), the second end of the refrigerant bypass pipe (2) being connected to the air pipe (12), and the refrigerant bypass pipe (2) being provided with a bypass valve (21); The control method comprises the following steps: Obtain the operating mode of the target indoor unit in the multi-split air conditioning system; Controlling the switching of an indoor electronic expansion valve (14) and a bypass valve (21) of the target indoor unit according to the acquired operation mode; When the operation mode is the ultra-low temperature heating start-up mode, the indoor electronic expansion valve (14) is controlled to be closed and the bypass valve (21) is controlled to be opened, so that the refrigerant discharged from the compressor (100) flows from the refrigerant bypass pipe (2) into the liquid pipe (13), and when the indoor air pipe temperature sensing package detects a temperature greater than T2, the operation mode is controlled to be switched from the ultra-low temperature heating start-up mode to the normal heating mode. When the operation mode is the normal heating mode, the indoor electronic expansion valve (14) is controlled to be opened and the bypass valve (21) is controlled to be closed, so that the refrigerant discharged from the compressor (100) flows from the heat exchange core (11) into the liquid pipe (13); When the ultra-low temperature heating start-up mode is operated, the method further includes controlling the indoor electronic expansion valve (14) to open at a first preset time interval and then close again after a second preset time interval.

2. The control method according to claim 1, characterized in that: The bypass valve (21) is an electric ball valve.

3. The control method according to claim 1, characterized in that: A bypass throttling element (22) is provided on the refrigerant bypass pipe (2), and the bypass throttling element (22) is located on a side of the bypass valve (21) close to the gas pipe (12).

4. The control method according to claim 3, characterized in that: The bypass throttling element (22) is a capillary tube.

5. The control method according to claim 1, characterized in that: The gas pipe (12) is provided with a gas pipe stop valve (121), and the second end of the refrigerant bypass pipe (2) is connected to a side of the gas pipe stop valve (121) away from the heat exchange core (11).

6. The control method according to claim 1, characterized in that: The gas pipe (12) is connected to the heat exchange tubes in the heat exchange core (11) via the gas collecting pipe (122); and / or the liquid pipe (13) is connected to the heat exchange tubes in the heat exchange core (11) via the flow divider (131).

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