Multi-link system and its control method

Abstract

The present invention discloses a multi-split system and a control method for the multi-split system. The multi-split system includes: a compressor, an outdoor heat exchanger assembly, a throttling assembly, and an indoor heat exchanger assembly connected in sequence to form a refrigerant circulation loop; the outdoor heat exchanger assembly has an air-cooled heat exchanger and a water-cooled heat exchanger connected in series, and both the air-cooled heat exchanger and the water-cooled heat exchanger can be independently switched to or disconnected from the refrigerant circulation loop; when the refrigerant circulation loop is running, at least one heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop. The present invention uses an air-cooled heat exchanger and a water-cooled heat exchanger connected in series. The two heat exchangers can be independently connected to the refrigerant circulation loop for operation, or can be connected to the refrigerant circulation loop for operation together. The working mode switching is flexible and can adapt to the use requirements under various loads and working conditions. The reliability and energy saving performance of the multi-split system are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-split units, and in particular to a multi-split unit configured with two heat exchange modes, air cooling and water cooling, and a control method for the multi-split unit. Background Art

[0002] The air-cooled VRFs and water-source VRFs currently on the market, while offering significant advantages, also have drawbacks that restrict industry development. Air-cooled VRFs offer advantages such as simple control, low engineering installation requirements, high reliability, and rapid cooling and heating. However, they also suffer from issues such as frosting during heating, time-consuming defrosting, and high-pressure protection during conventional cooling or cooling oil return in high-temperature environments. Water-cooled VRFs offer advantages such as high heat exchange efficiency and generally continuous operation during heating (no need to switch to cooling mode for defrosting). However, they place high demands on water quality and flow rate, and excessively high water flow rates are difficult to meet in actual projects.

[0003] Based on the advantages and disadvantages of air-cooled multi-split units and water-cooled multi-split units, existing technologies attempt to combine the two in parallel. For example, a dual-source heat pump unit uses a finned condenser and a shell-and-tube condenser in parallel. The finned condenser is used in the case of air source (air cooling), and the shell-and-tube condenser is used in the case of water source (water cooling). Although different condensers can be used in different working conditions, there are still great limitations in actual use. When the two condensers are used separately, it is difficult to meet the use requirements of special working conditions such as high-temperature cooling, low-temperature heating, and low-temperature defrosting, and the user experience is relatively poor. When the two condensers are used at the same time, there is a difference in the temperature of the refrigerant delivered by the condenser, which affects the reliability of the unit operation. Summary of the Invention

[0004] In order to solve the problem that the existing heat pump units cannot adapt to mode switching under different loads and working conditions, the present invention proposes a multi-split system and a control method for the multi-split system. The multi-split system adopts an air-cooled heat exchanger and a water-cooled heat exchanger connected in series. The two heat exchangers can be connected to the refrigerant circulation loop independently or together to work. The working mode switching is flexible and can adapt to the usage requirements under various loads and working conditions. The reliability and energy saving of the multi-split system are greatly improved.

[0005] The technical solution adopted by the present invention is to design a multi-split unit, including: a compressor, an outdoor heat exchanger assembly, a throttling assembly and an indoor heat exchanger assembly connected in sequence to form a refrigerant circulation loop; the outdoor heat exchanger assembly has an air-cooled heat exchanger and a water-cooled heat exchanger connected in series, and both the air-cooled heat exchanger and the water-cooled heat exchanger can be independently switched to or from the refrigerant circulation loop; when the refrigerant circulation loop is running, at least one heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop.

[0006] In some embodiments, both the air-cooled heat exchanger and the water-cooled heat exchanger are configured with a bypass line connected in parallel therewith, and by switching the on / off state of the bypass line, the corresponding heat exchanger is connected to or disconnected from the refrigerant circulation loop.

[0007] In some embodiments, the water-cooled heat exchanger is connected to the outlet side of the air-cooled heat exchanger when it serves as a condenser; the bypass line of the air-cooled heat exchanger is a first bypass line, and the first bypass line connects both ends of the air-cooled heat exchanger; the bypass line of the water-cooled heat exchanger includes: a second bypass line and a third bypass line, and the end of the water-cooled heat exchanger close to the air-cooled heat exchanger is connected to the inlet side of the indoor heat exchanger assembly when it serves as an evaporator through the second bypass line, and the other end of the water-cooled heat exchanger away from the air-cooled heat exchanger is connected to the inlet side of the indoor heat exchanger assembly when it serves as an evaporator through the third bypass line.

[0008] Furthermore, the throttling assembly includes: a first throttle valve installed on the outlet side of the air-cooled heat exchanger when it is used as a condenser, and a third throttle valve installed on the third bypass line; a first control valve is installed on the first bypass line, and a second control valve is installed on the second bypass line.

[0009] In some embodiments, the indoor heat exchanger assembly is configured with a fourth bypass line connected in parallel therewith, and a fourth control valve is installed on the fourth bypass line; the other end of the water-cooled heat exchanger away from the air-cooled heat exchanger is directly connected to the suction side of the compressor through the fourth bypass line, and by switching the on-off state of the second bypass line to the fourth bypass line, the indoor heat exchanger assembly is disconnected from or connected to the refrigerant circulation loop.

[0010] Furthermore, the refrigerant circulation circuit is further provided with a four-way valve for switching the refrigerant circulation flow direction, and the operating modes of the multi-split unit include at least two of: air-cooled refrigeration mode, water-cooled refrigeration mode, dual-cold source refrigeration mode, air-cooled heating mode, water-cooled heating mode, dual-heat source heating mode, oil return mode, and defrost mode;

[0011] When the multi-split system is in air-cooling mode, the refrigerant circulation loop runs the refrigeration cycle, and only the air-cooled heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, while the indoor heat exchanger assembly is connected to the refrigerant circulation loop;

[0012] and / or when the VRF is in water-cooling mode, the refrigerant circulation loop operates a refrigeration cycle, only the water-cooled heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop;

[0013] and / or when the VRF is in dual-cooling source cooling mode, the refrigerant circulation loop operates a refrigeration cycle, the air-cooled heat exchanger and the water-cooled heat exchanger in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop;

[0014] and / or when the VRF is in air-cooling and heating mode, the refrigerant circulation loop operates a heating cycle, only the air-cooling heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop;

[0015] and / or when the VRF is in water-cooling and heating mode, the refrigerant circulation loop operates a heating cycle, only the water-cooling heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop;

[0016] and / or when the VRF is in dual-heat-source heating mode, the refrigerant circulation loop operates a heating cycle, the air-cooled heat exchanger and the water-cooled heat exchanger in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop;

[0017] and / or when the VRF is in oil return mode, the refrigerant circulation loop operates a refrigeration cycle, the air-cooled heat exchanger and the water-cooled heat exchanger in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop;

[0018] And / or when the multi-split unit is in defrost mode, the refrigerant circulation loop runs a refrigeration cycle, the air-cooled heat exchanger and the water-cooled heat exchanger in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is disconnected from the refrigerant circulation loop.

[0019] In some embodiments, the water circuit of the water-cooled heat exchanger is connected to a water circulation loop, which is provided with a cooling device for regulating the water temperature and a water pump for driving the water flow.

[0020] Furthermore, the water circulation loop is also provided with a terminal device arranged in parallel with the water-cooled heat exchanger.

[0021] The present invention also proposes a control method applied to the above-mentioned multi-connected machine, which has at least two different working modes, and each working mode is set with its corresponding entry conditions; the control method includes: obtaining the control mode of the multi-connected machine; if the control mode is automatic mode, collecting the operating parameters of the multi-connected machine, comparing the operating parameters with the entry conditions of different working modes, and when the operating parameters meet the entry conditions of any working mode, switching the multi-connected machine to the corresponding working mode.

[0022] In some embodiments, the operating modes of the VRF include at least two of: an air-cooling cooling mode, a water-cooling cooling mode, a dual-cold-source cooling mode, an air-cooling heating mode, a water-cooling heating mode, a dual-heat-source heating mode, an oil return mode, and a defrost mode;

[0023] The entry conditions for the dual-cold source cooling mode are: the outdoor ambient temperature > the first set high temperature or the compressor exhaust side pressure > the first set high pressure;

[0024] The entry condition of oil return mode is that the outdoor ambient temperature is greater than the second set high temperature or the exhaust side pressure of the compressor is greater than the second set high pressure;

[0025] The conditions for entering the dual-heat source heating mode or water-cooled heating mode are: the lower set low temperature < outdoor ambient temperature ≤ upper set low temperature, and the inlet and outlet water temperatures of the water-cooled heat exchanger are both ≥ the set water temperature;

[0026] The entry conditions for the defrost mode are: the outdoor ambient temperature < the upper limit set low temperature, and the suction side pressure of the compressor < the set low pressure;

[0027] Among them, the first set high temperature>the second set high temperature, and the first set high pressure>the second set high pressure.

[0028] Furthermore, the control method further includes:

[0029] In automatic mode, detect whether the heat exchanger connected to the refrigerant circulation loop in the outdoor heat exchanger assembly has a heat exchange failure;

[0030] If a heat exchange failure occurs in the air-cooled heat exchanger, the multi-split operating mode is switched so that the refrigerant circulation direction of the refrigerant circulation loop remains unchanged, the water-cooled heat exchanger is connected to the refrigerant circulation loop, and the air-cooled heat exchanger is disconnected from the refrigerant circulation loop;

[0031] If a heat exchange failure occurs in the water-cooled heat exchanger, the VLSI operating mode is switched so that the refrigerant circulation direction of the refrigerant circulation loop remains unchanged, the air-cooled heat exchanger is connected to the refrigerant circulation loop, and the water-cooled heat exchanger is disconnected from the refrigerant circulation loop;

[0032] If both the water-cooled heat exchanger and the air-cooled heat exchanger have heat exchange failures, the multi-connected system will be shut down.

[0033] Furthermore, the control method further includes: if the control mode is manual mode, controlling the multi-link system to enter a corresponding working mode according to the instructions input by the user.

[0034] In some embodiments, the control method further includes: the multi-split system enters automatic mode by default after being powered on, and switches to manual mode after receiving an instruction input by the user.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The outdoor heat exchanger assembly uses an air-cooled heat exchanger and a water-cooled heat exchanger connected in series. The two heat exchangers can be connected to the refrigerant circulation loop independently or together. The working mode switching is flexible and better meets user needs.

[0037] 2. Design precise working mode judgment conditions. When the outdoor temperature is too low, determine the frost condition of the outdoor heat exchanger and whether there is any risk in running water cooling. When the outdoor temperature is too high, determine whether water cooling must be started. Intelligently switch working modes according to load and operating conditions, greatly improving the reliability and energy saving of the multi-split system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention is described in detail below with reference to the embodiments and accompanying drawings, in which:

[0039] Figure 1 is a connection diagram of the air conditioning system of the present invention;

[0040] Figure 2 This is a schematic diagram of the operation of the air-cooling refrigeration mode of the present invention;

[0041] Figure 3 This is a schematic diagram of the operation of the air cooling and heating mode of the present invention;

[0042] Figure 4 Schematic diagram of the operation of the water-cooling refrigeration mode of the present invention;

[0043] Figure 5 It is a schematic diagram of the operation of the water cooling and heating mode of the present invention;

[0044] Figure 6 Schematic diagram of the operation of the dual-cold source refrigeration mode of the present invention;

[0045] Figure 7 Schematic diagram of the operation of the dual heat source heating mode of the present invention;

[0046] Figure 8 Schematic diagram of the operation of the oil return mode of the present invention;

[0047] Figure 9 Schematic diagram of the operation of the defrost mode of the present invention;

[0048] Figure 10 This is a control schematic diagram of the present invention in the cooling mode;

[0049] Figure 11 It is a control schematic diagram of the present invention in the heating mode. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0051] like Figure 1As shown, the multi-split system proposed in the present invention is configured with two heat exchange modes: air cooling and water cooling. The refrigerant circulation loop of the multi-split system is formed by a compressor 1, an outdoor heat exchanger assembly, a throttling assembly, and an indoor heat exchanger assembly 10 connected in sequence. The exhaust port of the compressor 1 is connected to an oil separator, the intake port of the compressor 1 is connected to a gas-liquid separator, and the indoor heat exchanger assembly 10 has at least one indoor heat exchanger. The outdoor heat exchanger assembly has an air-cooled heat exchanger 3 and a water-cooled heat exchanger 8. The air-cooled heat exchanger 3 can adopt a common fin-type heat exchanger, and the water-cooled heat exchanger 8 can adopt a common plate-type heat exchanger. The two heat exchangers are connected in series. Here, "series connection" means that the air-cooled heat exchanger 3 and the water-cooled heat exchanger 8 are connected in series in the refrigerant circulation loop, that is, when the air-cooled heat exchanger 3 and the water-cooled heat exchanger 8 are both connected to the refrigerant circulation loop, the refrigerant passes through the air-cooled heat exchanger 3 and the water-cooled heat exchanger 8 in sequence. The order of the two can be designed according to actual needs.

[0052] Based on the series connection of air-cooled heat exchanger 3 and water-cooled heat exchanger 8, each can be independently switched in and out of the refrigerant circulation loop. When the refrigerant circulation loop is in operation, at least one heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop. In other words, the two heat exchangers can be connected to the refrigerant circulation loop independently or together, allowing flexible switching of operating modes to better meet user needs.

[0053] It should be pointed out that the air-cooled heat exchanger 3 and the water-cooled heat exchanger 8 can be connected in series or in parallel. Taking the dual-source heat pump unit mentioned in the background technology as an example, the parallel connection has the following defects: 1. The refrigerant in the refrigerant circulation loop can pass through at most one of the heat exchangers between the fin-type condenser and the shell and tube condenser. The heat exchange capacity is limited and it is difficult to meet the use requirements of special working conditions such as high-temperature cooling and low-temperature heating; 2. When the two heat exchangers are set in parallel, during the defrosting process of the fin-type condenser, the shell and tube condenser cannot be used as an evaporator. The low-temperature refrigerant flowing out after defrosting must pass through the indoor heat exchanger, causing the indoor temperature to fluctuate, affecting the user experience; 3. Due to the different heat exchange efficiencies of the two heat exchangers, the parallel setting will lead to differences in the refrigerant temperatures sent from the two heat exchangers, affecting the reliability of the unit operation. The present invention connects the air-cooled heat exchanger and the water-cooled heat exchanger in series. The series connection has the following advantages: 1. When the two heat exchangers are connected to the refrigerant circulation loop at the same time, the refrigerant passes through the two heat exchangers in sequence, that is, the refrigerant sent out of the outdoor heat exchanger assembly all passes through the air-cooled heat exchanger 3 and the water-cooled heat exchanger 8, and the heat exchange capacity of the outdoor heat exchanger assembly is significantly improved, which can meet the use requirements of special working conditions such as high-temperature refrigeration and low-temperature heating; 2. When the two heat exchangers are set in series, during the defrosting process of the air-cooled heat exchanger 3, the water-cooled heat exchanger 8 can be used as an evaporator. The low-temperature refrigerant flowing out after defrosting is directly sent back to the compressor through the water-cooled heat exchanger 8, the indoor temperature is stable, and the user experience is better; 3. Since the refrigerant passes through the two heat exchangers in sequence, the problem of refrigerant temperature difference in parallel setting is avoided, the refrigerant in each part of the refrigerant circulation loop is stable, and the reliability of the unit operation is improved.

[0054] Specifically, to enable flexible switching between the two heat exchangers and simplify the piping connection structure, both the air-cooled heat exchanger 3 and the water-cooled heat exchanger 8 are equipped with bypass lines connected in parallel. Because the resistance of the refrigerant flowing through the heat exchanger and the bypass line is different, the corresponding heat exchanger can be connected or disconnected from the refrigerant circulation loop by switching the bypass line on and off. For example, when the bypass line of the air-cooled heat exchanger 3 is connected, the air-cooled heat exchanger 3 is disconnected from the refrigerant circulation loop, and when the bypass line of the water-cooled heat exchanger 8 is connected, the water-cooled heat exchanger 8 is disconnected from the refrigerant circulation loop.

[0055] In some embodiments of the present invention, the water-cooled heat exchanger 8 is connected to the outlet side of the air-cooled heat exchanger 3 when it functions as a condenser. The bypass line of the air-cooled heat exchanger 3 is a first bypass line, which connects both ends of the air-cooled heat exchanger 3. That is, one end of the first bypass line is connected to the inlet side of the air-cooled heat exchanger 3 when it functions as a condenser, and the other end of the first bypass line is connected to the outlet side of the air-cooled heat exchanger 3 when it functions as a condenser. The bypass line of the water-cooled heat exchanger 8 includes a second bypass line and a third bypass line. The end of the water-cooled heat exchanger 8 closest to the air-cooled heat exchanger 3 is connected to the inlet side of the indoor heat exchanger assembly 10 when it functions as an evaporator via the second bypass line, and the other end of the water-cooled heat exchanger 8 away from the air-cooled heat exchanger 3 is connected to the inlet side of the indoor heat exchanger assembly 10 when it functions as an evaporator via the third bypass line.

[0056] In some embodiments of the present invention, the throttling assembly includes: a first throttle valve 5 and a third throttle valve 7. The first throttle valve 5 is installed on the outlet side of the air-cooled heat exchanger when it is used as a condenser. The third throttle valve 7 is installed on the third bypass line. The first bypass line is installed with a first control valve 4, and the second bypass line is installed with a second control valve 6. It should be noted that in this embodiment, since the valve components on the second bypass line do not need to have a throttling function and only need to switch the on-off state of the second bypass line, the second control valve 6 can be a throttle valve or a switch valve. In actual application, the number and position of the throttle valves in the throttling assembly can be adjusted and designed according to the flow direction of the refrigerant.

[0057] Furthermore, to optimize the performance of the VRF system and better meet user needs, the indoor heat exchanger assembly 10 is also equipped with a fourth bypass line connected in parallel therewith. A fourth control valve 11 is installed on the fourth bypass line. The other end of the water-cooled heat exchanger 8, away from the air-cooled heat exchanger 3, is directly connected to the suction side of the compressor 1 via the fourth bypass line. By switching the on / off state of the second bypass line to the fourth bypass line, the indoor heat exchanger assembly 10 is disconnected from or connected to the refrigerant circulation loop. Since the valve on the fourth bypass line does not need to have a throttling function and only needs to switch the on / off state of the fourth bypass line, the fourth control valve 11 can be a throttling valve or an on / off valve.

[0058] like Figure 1 As shown, based on the above-mentioned pipeline connection structure, the refrigerant circulation circuit is also provided with a four-way valve 2 for switching the refrigerant circulation flow direction. The refrigerant circulation circuit can run a refrigeration cycle or a heating cycle. The working modes of the multi-split unit include: air-cooled refrigeration mode, water-cooled refrigeration mode, dual-cold source refrigeration mode, air-cooled heating mode, water-cooled heating mode, dual-heat source heating mode, oil return mode, and at least two of the defrost mode. The working status of each mode is described in detail below.

[0059] like Figure 2As shown, when the multi-split unit is in air-cooled refrigeration mode, the refrigerant circulation loop runs the refrigeration cycle, the first control valve 4 is closed, the first throttle valve 5 is opened and plays a throttling role, the second control valve 6 is opened, the third throttle valve 7 is closed, and the fourth control valve 11 is closed. Only the air-cooled heat exchanger 3 in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly 10 is connected to the refrigerant circulation loop. The high-temperature refrigerant discharged from the compressor 1 passes through the air-cooled heat exchanger 3, the first throttle valve 5, the second control valve 6, and the indoor heat exchanger assembly 10 in sequence, and then returns to the intake port of the compressor 1.

[0060] like Figure 4 As shown, when the multi-split unit is in water-cooled refrigeration mode, the refrigerant circulation loop runs the refrigeration cycle, the first control valve 4 is opened, the first throttle valve 5 is closed, the second control valve 6 is closed, the third throttle valve 7 is opened and plays a throttling role, the fourth control valve 11 is closed, and only the water-cooled heat exchanger 8 in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly 10 is connected to the refrigerant circulation loop. The high-temperature refrigerant discharged from the compressor 1 passes through the first control valve 4, the water-cooled heat exchanger 8, the third throttle valve 7, and the indoor heat exchanger assembly 10 in sequence, and then returns to the intake port of the compressor 1.

[0061] like Figure 6 As shown, when the VRF is in dual-cold-source cooling mode, the refrigerant circulation loop operates the refrigeration cycle, the first control valve 4 is closed, the first throttle valve 5 is open, the second control valve 6 is closed, the third throttle valve 7 is open and acts as a throttling valve, the fourth control valve 11 is closed, the air-cooled heat exchanger 3 and the water-cooled heat exchanger 8 in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly 10 is connected to the refrigerant circulation loop. The high-temperature refrigerant discharged from the compressor 1 passes through the air-cooled heat exchanger 3, the first throttle valve 5, the water-cooled heat exchanger 8, the third throttle valve 7, and the indoor heat exchanger assembly 10 in sequence before returning to the intake port of the compressor 1. The dual-cold-source cooling mode is suitable for cooling conditions with high outdoor ambient temperature and heavy unit load. The high-temperature refrigerant discharged from the compressor is cooled by the air-cooled heat exchanger and the water-cooled heat exchanger in sequence, effectively improving the unit's cooling capacity to meet user cooling needs.

[0062] like Figure 3 As shown, when the multi-split unit is in the air-cooling and heating mode, the refrigerant circulation loop runs the heating cycle, the first control valve 4 is closed, the first throttle valve 5 is opened and plays a throttling role, the second control valve 6 is opened, the third throttle valve 7 is closed, and the fourth control valve 11 is closed. Only the air-cooled heat exchanger 3 in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly 10 is connected to the refrigerant circulation loop. The high-temperature refrigerant discharged from the compressor 1 passes through the indoor heat exchanger assembly 10, the second control valve 6, the first throttle valve 5, and the air-cooled heat exchanger 3 in turn, and then returns to the intake port of the compressor 1.

[0063] like Figure 5As shown, when the multi-split unit is in the water-cooling heating mode, the refrigerant circulation loop runs the heating cycle, the first control valve 4 is opened, the first throttle valve 5 is closed, the second control valve 6 is closed, the third throttle valve 7 is opened and plays a throttling role, the fourth control valve 11 is closed, and only the water-cooled heat exchanger 8 in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly 10 is connected to the refrigerant circulation loop. The high-temperature refrigerant discharged from the compressor 1 passes through the indoor heat exchanger assembly 10, the third throttle valve 7, the water-cooled heat exchanger 8, and the first control valve 4 in sequence, and then returns to the intake port of the compressor 1.

[0064] like Figure 7 As shown, when the VRF is in dual-heat-source heating mode, the refrigerant circulation loop operates a heating cycle, the first control valve 4 is closed, the first throttle valve 5 is open, the second control valve 6 is closed, the third throttle valve 7 is open and acts as a throttling valve, and the fourth control valve 11 is closed. The air-cooled heat exchanger 3 and the water-cooled heat exchanger 8 in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly 10 is connected to the refrigerant circulation loop. The high-temperature refrigerant discharged from the compressor 1 passes through the indoor heat exchanger assembly 10, the third throttle valve 7, the water-cooled heat exchanger 8, the first throttle valve 5, and the air-cooled heat exchanger 3 in sequence before returning to the intake port of the compressor 1. The dual-heat-source heating mode is suitable for heating conditions with low outdoor ambient temperature and heavy unit load. The low-temperature refrigerant delivered from the indoor heat exchanger assembly is heated successively by the water-cooled heat exchanger and the air-cooled heat exchanger, effectively improving the unit's heating capacity to meet the user's heating needs.

[0065] like Figure 8 As shown, when the multi-split unit is in the oil return mode, the refrigerant circulation loop runs the refrigeration cycle, the first control valve 4 is closed, the first throttle valve 5 is opened, the second control valve 6 is closed, the third throttle valve 7 is opened and plays a throttling role, the fourth control valve 11 is closed, the air-cooled heat exchanger 3 and the water-cooled heat exchanger 8 in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly 10 is connected to the refrigerant circulation loop. The high-temperature refrigerant discharged from the compressor 1 passes through the air-cooled heat exchanger 3, the first throttle valve 5, the water-cooled heat exchanger 8, the third throttle valve 7, and the indoor heat exchanger assembly 10 in sequence, and then returns to the intake port of the compressor 1.

[0066] like Figure 9As shown, when the VRF is in defrost mode, the refrigerant circulation loop operates a refrigeration cycle, the first control valve 4 is closed, the first throttle valve 5 is open and acts as a throttling valve, the second control valve 6 is closed, the third throttle valve 7 is closed, and the fourth control valve 11 is open. The air-cooled heat exchanger 3 and the water-cooled heat exchanger 8 in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly 10 is disconnected from the refrigerant circulation loop. The high-temperature refrigerant discharged from the compressor 1 passes through the air-cooled heat exchanger 3, the first throttle valve 5, the water-cooled heat exchanger 8, and the fourth control valve 11 in sequence before returning to the intake port of the compressor 1. Since the indoor heat exchanger assembly in defrost mode is disconnected from the refrigerant circulation loop, the impact of low-temperature refrigerant on the indoor environment is effectively prevented, indoor temperature fluctuations are avoided, and the user experience is improved.

[0067] It should be noted that the above operating modes can be flexibly configured according to user needs. For example, in application scenarios where there is little or no heating demand, the multi-split system may not need to be configured with a heating mode or a defrost mode. For another example, in application scenarios where there is little or no cooling demand, the multi-split system may not need to be configured with a cooling mode. Of course, the preferred solution is for the multi-split system to be configured with all the above operating modes simultaneously, but the present invention does not impose any particular limitation on the specific number and types of operating modes.

[0068] like Figure 1 As shown, in some embodiments of the present invention, the water path of the water-cooled heat exchanger 8 is connected to a water circulation loop, and the water circulation loop is provided with a cooling device 12 for adjusting the water temperature and a water pump 9 for driving the flow of water. The cooling device 12 can be a cooling tower, etc. The water is cooled by passing through the cooling device 12. The water circulation loop can also be installed with a regulating valve for controlling the water flow.

[0069] Furthermore, in order to fully utilize the excess energy of the water circulation loop, the water circulation loop is also provided with a terminal device 13 arranged in parallel with the water-cooled heat exchanger 8. For example, in the defrost mode, the high-temperature refrigerant discharged by the compressor 1 enters the air-cooled heat exchanger 3 for defrosting. After the refrigerant flowing out of the air-cooled heat exchanger 3 passes through the first throttle valve 5, the low-temperature liquid refrigerant enters the water-cooled heat exchanger 8 to provide cooling to the water-cooled heat exchanger 3. At this time, the low-temperature water flowing out of the water-cooled heat exchanger 8 can provide cooling to the terminal device 13, realizing the recovery and utilization of excess cooling capacity. For another example, in the dual-heat source heating mode, after the refrigerant flowing out of the indoor heat exchanger assembly 10 passes through the third throttle valve 7, the low-temperature liquid refrigerant enters the water-cooled heat exchanger 8 to provide cooling to the water-cooled heat exchanger 8. At this time, the low-temperature water flowing out of the water-cooled heat exchanger 8 can provide cooling to the terminal device 13, realizing the recovery and utilization of excess cooling capacity.

[0070] The present invention also proposes a control method applied to the above-mentioned multi-connected machine. The multi-connected machine has at least two different working modes. Each working mode is set with its corresponding entry condition. The value of the entry condition is obtained in advance through experimental statistics. After the multi-connected machine is started, the controller executes the control method to switch the working mode of the multi-connected machine.

[0071] The control method includes: obtaining the control mode of the multi-connected machine; if the control mode is automatic mode, collecting the operating parameters of the multi-connected machine, comparing the operating parameters with the entry conditions of different working modes, and when the operating parameters meet the entry conditions of any working mode, switching the multi-connected machine to the corresponding working mode.

[0072] In some embodiments of the present invention, the operating modes of the multi-split system include: at least two of: air-cooled refrigeration mode, water-cooled refrigeration mode, dual-cold source refrigeration mode, air-cooled heating mode, water-cooled heating mode, dual-heat source heating mode, oil return mode, and defrost mode.

[0073] For use scenarios with cooling needs, after the multi-split system is started, it usually operates in air-cooled cooling mode or water-cooled cooling mode under normal circumstances. The entry conditions for the dual-cold source cooling mode are: outdoor ambient temperature > first set high temperature or compressor exhaust side pressure > first set high pressure; the entry conditions for the oil return mode are: outdoor ambient temperature > second set high temperature or compressor exhaust side pressure > second set high pressure.

[0074] like Figure 10 As shown, when the multi-split unit is started for cooling and the control mode of the multi-split unit is automatic mode, the outdoor ambient temperature and the exhaust side pressure of the compressor of the multi-split unit are collected. If the entry conditions of the dual-cold source cooling mode are met, it means that the outdoor ambient temperature is high and the unit load is large, and the cooling capacity of the unit needs to be improved. If the entry conditions of the oil return mode are met, it means that the unit is in poor operating condition and oil return operation is required to ensure the normal operation of the compressor. If the dual-cold source cooling mode or the oil return mode is not reached, the current operating mode is maintained and continued to operate.

[0075] It should be noted that since the oil return process requires the compressor to run at a high frequency, the exhaust pressure of the compressor will increase significantly during this time. Therefore, the first set high temperature > the second set high temperature, and the first set high pressure > the second set high pressure. In other words, the entry conditions for the oil return mode are lower than those for the dual-cold source cooling mode. This is to reserve room for the compressor to increase the frequency and avoid high-pressure shutdown protection in the multi-split system during the oil return process. In a specific application example of the present invention, the first set high pressure is 3.2MPa, the second set high pressure is 3.0MPa, the first set high temperature is 50°C, and the second set high temperature is 48°C.

[0076] In scenarios where heating is required, after the VRF system is started, it normally operates in air-cooled heating mode or water-cooled heating mode. The entry conditions for dual-heat source heating mode or water-cooled heating mode are: The entry conditions for dual-heat source heating mode are: the lower set low temperature < the outdoor ambient temperature ≤ the upper set low temperature, and both the inlet and outlet water temperatures of the water-cooled heat exchanger are ≥ the set water temperature; the entry conditions for defrost mode are: the outdoor ambient temperature < the upper set low temperature, and the compressor suction side pressure < the set low pressure. In a specific application example of the present invention, the lower set low temperature is -15°C, the upper set low temperature is 0°C, the set water temperature is 2°C, and the set low pressure is 0.577MPa.

[0077] like Figure 11 As shown, when the multi-split unit is started for heating and the control mode of the multi-split unit is in automatic mode, the outdoor ambient temperature of the multi-split unit, the suction side pressure of the compressor, and the inlet and outlet water temperatures of the water-cooled heat exchanger are collected. If the entry conditions for the dual-heat source heating mode or the water-cooled heating mode are met, the dual-heat source heating mode or the water-cooled heating mode is selected according to the current indoor load. When the heating capacity of the multi-split unit can meet the indoor load, it switches to the water-cooled heating mode to extend the normal heating time before the unit enters the defrost mode. When the heating capacity of the multi-split unit cannot meet the indoor load, it switches to the dual-heat source heating mode to improve the heating capacity of the unit. If the entry conditions for the defrost mode are met, it means that the unit is in poor operating condition and the frost layer on the air-cooled heat exchanger may be very thick, requiring defrosting operation to ensure the normal operation of the compressor. If the dual-heat source heating mode, the water-cooled heating mode or the defrost mode is not met, the current operating mode is maintained and continued to operate.

[0078] In some embodiments of the present invention, in order to switch the working mode more intelligently, the control method further includes:

[0079] In automatic mode, detect whether the heat exchanger connected to the refrigerant circulation loop in the outdoor heat exchanger assembly has a heat exchange failure;

[0080] If a heat exchange failure occurs in the air-cooled heat exchanger, the multi-split operating mode is switched so that the refrigerant circulation direction of the refrigerant circulation loop remains unchanged, the water-cooled heat exchanger is connected to the refrigerant circulation loop, and the air-cooled heat exchanger is disconnected from the refrigerant circulation loop;

[0081] If a heat exchange failure occurs in the water-cooled heat exchanger, the VLSI operating mode is switched so that the refrigerant circulation direction of the refrigerant circulation loop remains unchanged, the air-cooled heat exchanger is connected to the refrigerant circulation loop, and the water-cooled heat exchanger is disconnected from the refrigerant circulation loop;

[0082] If both the water-cooled heat exchanger and the air-cooled heat exchanger have heat exchange failures, the multi-connected system will be shut down.

[0083] like Figure 10As shown, when the multi-split system is started for cooling and the control mode of the multi-split system is in automatic mode, if the multi-split system operates in air-cooled cooling mode or dual-cold source cooling mode, the air-cooled heat exchanger is detected to see if it is faulty. If a heat exchange failure occurs in the air-cooled heat exchanger, the system switches to water-cooled cooling mode. If both the water-cooled heat exchanger and the air-cooled heat exchanger have heat exchange failures, the multi-split system is shut down. If the multi-split system operates in water-cooled cooling mode or dual-cold source cooling mode, the water-cooled heat exchanger is detected to see if it is faulty. If a heat exchange failure occurs in the water-cooled heat exchanger, the system switches to air-cooled cooling mode. If both the water-cooled heat exchanger and the air-cooled heat exchanger have heat exchange failures, the multi-split system is shut down.

[0084] like Figure 11 As shown, when the multi-split system is started for heating and the control mode of the multi-split system is in automatic mode, if the multi-split system operates in air-cooled heating mode or dual-cold source heating mode, the air-cooled heat exchanger is detected to see if it is faulty. If a heat exchange failure occurs in the air-cooled heat exchanger, the system switches to water-cooled heating mode. If both the water-cooled heat exchanger and the air-cooled heat exchanger have heat exchange failures, the multi-split system is shut down. If the multi-split system operates in water-cooled heating mode or dual-cold source heating mode, the water-cooled heat exchanger is detected to see if it is faulty. If a heat exchange failure occurs in the water-cooled heat exchanger, the system switches to air-cooled heating mode. If both the water-cooled heat exchanger and the air-cooled heat exchanger have heat exchange failures, the multi-split system is shut down.

[0085] It should be pointed out that heat exchange failure in air-cooled heat exchangers refers to factors affecting the heat exchange of air-cooled heat exchangers, such as fan failure and fan drive board failure. Heat exchange failure in water-cooled heat exchangers refers to factors affecting the heat exchange of water-cooled heat exchangers, such as the inability to start or failure of the water pump, abnormal water flow, abnormal water temperature, etc. During specific design, the corresponding fault evaluation indicators can be selected according to actual conditions.

[0086] like Figure 10 、 11 As shown, in some embodiments of the present invention, the control method further includes: if the control mode is manual mode, controlling the multi-split system to enter a corresponding operating mode according to a command input by the user. The control mode of the multi-split system can be manually selected by the user, or it can be set to enter automatic mode by default after the multi-split system is powered on and switch to manual mode after receiving a command input by the user.

[0087] It should be understood that in automatic mode, fault detection takes precedence over mode entry conditions. This means that when a heat exchanger failure occurs, the corresponding mode is prioritized. Manual mode takes precedence over automatic mode, and the VRF controller strictly follows user instructions to control the VRF's operating mode.

[0088] It should be noted that the terms used above are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0089] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Multi-connection, including: The compressor, the outdoor heat exchanger assembly, the throttling assembly and the indoor heat exchanger assembly are connected in sequence to form a refrigerant circulation loop; it is characterized in that the outdoor heat exchanger assembly has an air-cooled heat exchanger and a water-cooled heat exchanger connected in series, and the air-cooled heat exchanger and the water-cooled heat exchanger can be independently switched to or from the refrigerant circulation loop; when the refrigerant circulation loop is running, at least one heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop; the bypass pipe of the water-cooled heat exchanger includes: a second bypass pipe and a third bypass pipe, one end of the water-cooled heat exchanger close to the air-cooled heat exchanger is connected to the inlet side of the indoor heat exchanger assembly when it is used as an evaporator through the second bypass pipe, and the other end of the water-cooled heat exchanger away from the air-cooled heat exchanger is connected to the inlet side of the indoor heat exchanger assembly when it is used as an evaporator through the third bypass pipe; The indoor heat exchanger assembly is configured with a fourth bypass line connected in parallel therewith, and a fourth control valve is installed on the fourth bypass line; the other end of the water-cooled heat exchanger away from the air-cooled heat exchanger is directly connected to the suction side of the compressor through the fourth bypass line, and the indoor heat exchanger assembly is disconnected from or connected to the refrigerant circulation loop by switching the on-off state of the second bypass line to the fourth bypass line.

2. The multi-split system according to claim 1, characterized in that: The water-cooled heat exchanger is connected to the outlet side of the air-cooled heat exchanger when it serves as a condenser; the bypass line of the air-cooled heat exchanger is a first bypass line, and the first bypass line connects both ends of the air-cooled heat exchanger.

3. The multi-split system according to claim 2, characterized in that: The throttling assembly includes: a first throttle valve installed on the outlet side of the air-cooled heat exchanger when it is used as a condenser, and a third throttle valve installed on the third bypass line; a first control valve is installed on the first bypass line, and a second control valve is installed on the second bypass line.

4. The multi-split system according to claim 1, characterized in that: The refrigerant circulation circuit is further provided with a four-way valve for switching the refrigerant circulation flow direction. The operating modes of the multi-split unit include: air-cooling refrigeration mode, water-cooling refrigeration mode, dual-cold source refrigeration mode, air-cooling heating mode, water-cooling heating mode, dual-heat source heating mode, oil return mode, and defrost mode. When the multi-split system is in air-cooling refrigeration mode, the refrigerant circulation loop runs a refrigeration cycle, only the air-cooling heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop; and / or when the multi-split system is in a water-cooling refrigeration mode, the refrigerant circulation loop runs a refrigeration cycle, only the water-cooled heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop; and / or when the multi-split system is in dual-cold-source cooling mode, the refrigerant circulation loop runs a refrigeration cycle, the air-cooled heat exchanger and the water-cooled heat exchanger in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop; and / or when the multi-split system is in air-cooling and heating mode, the refrigerant circulation loop runs a heating cycle, only the air-cooling heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop; and / or when the VRF is in water-cooling and heating mode, the refrigerant circulation loop runs a heating cycle, only the water-cooling heat exchanger in the outdoor heat exchanger assembly is connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop; And / or when the multi-split system is in dual-heat source heating mode, the refrigerant circulation loop runs a heating cycle, the air-cooled heat exchanger and the water-cooled heat exchanger in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop; and / or when the multi-split unit is in oil return mode, the refrigerant circulation loop runs a refrigeration cycle, the air-cooled heat exchanger and the water-cooled heat exchanger in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is connected to the refrigerant circulation loop; And / or when the multi-split unit is in defrost mode, the refrigerant circulation loop runs a refrigeration cycle, the air-cooled heat exchanger and the water-cooled heat exchanger in the outdoor heat exchanger assembly are both connected to the refrigerant circulation loop, and the indoor heat exchanger assembly is disconnected from the refrigerant circulation loop.

5. The multi-split system according to any one of claims 1 to 4, characterized in that: The water channel of the water-cooled heat exchanger is connected to a water circulation loop, and the water circulation loop is provided with a cooling device for regulating water temperature and a water pump for driving the water flow.

6. The multi-split system according to claim 5, characterized in that: The water circulation loop is further provided with a terminal device arranged in parallel with the water-cooled heat exchanger.

7. A control method for a multi-split system, the control method being applied to the multi-split system according to any one of claims 1 to 6, wherein the multi-split system has at least two different operating modes, each operating mode being provided with its corresponding entry condition; characterized in that: The control method includes: Obtaining a control mode of the multi-connection system; If the control mode is automatic mode, the operating parameters of the multi-connected system are collected, and the operating parameters are compared with the entry conditions of different working modes. When the operating parameters meet the entry conditions of any working mode, the multi-connected system is switched to the corresponding working mode.

8. The control method according to claim 7, characterized in that: The operating modes of the multi-split system include at least two of: air-cooling refrigeration mode, water-cooling refrigeration mode, dual-cold source refrigeration mode, air-cooling heating mode, water-cooling heating mode, dual-heat source heating mode, oil return mode, and defrost mode; The entry condition of the dual-cold-source cooling mode is that the outdoor ambient temperature is greater than the first set high temperature or the exhaust side pressure of the compressor is greater than the first set high pressure; The oil return mode is entered when the outdoor ambient temperature is greater than the second set high temperature or the exhaust side pressure of the compressor is greater than the second set high pressure; The entry conditions of the dual heat source heating mode or the water cooling heating mode are: the lower limit set low temperature < the outdoor ambient temperature ≤ the upper limit set low temperature, and the inlet water temperature and the outlet water temperature of the water cooling heat exchanger are both ≥ the set water temperature; The entry conditions of the defrost mode are that the outdoor ambient temperature is less than the upper limit set low temperature, and the suction side pressure of the compressor is less than the set low pressure; Among them, the first set high temperature>the second set high temperature, and the first set high pressure>the second set high pressure.

9. The control method according to claim 7, characterized in that: The control method further includes: In the automatic mode, detecting whether a heat exchanger connected to the refrigerant circulation loop in the outdoor heat exchanger assembly has a heat exchange failure; If a heat exchange failure occurs in the air-cooled heat exchanger, the operating mode of the multi-split system is switched so that the refrigerant circulation direction of the refrigerant circulation loop remains unchanged, the water-cooled heat exchanger is connected to the refrigerant circulation loop, and the air-cooled heat exchanger is disconnected from the refrigerant circulation loop; If a heat exchange failure occurs in the water-cooled heat exchanger, the operating mode of the multi-split system is switched so that the refrigerant circulation direction of the refrigerant circulation loop remains unchanged, the air-cooled heat exchanger is connected to the refrigerant circulation loop, and the water-cooled heat exchanger is disconnected from the refrigerant circulation loop; If both the water-cooled heat exchanger and the air-cooled heat exchanger have heat exchange failures, the multi-split system will be shut down.

10. The control method according to claim 7, characterized in that: The control method further includes: if the control mode is a manual mode, controlling the multi-link system to enter a corresponding working mode according to an instruction input by a user.

11. The control method according to claim 10, characterized in that: The control method further includes: the multi-split system enters the automatic mode by default after being powered on, and switches to the manual mode after receiving an instruction input by the user.

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