Double-machine-head four-stage magnetic suspension air energy heat pump cold and hot water unit and working method

Abstract

The invention discloses a double-machine-head four-stage magnetic suspension air energy heat pump cold and hot water unit which comprises a low-temperature-stage magnetic suspension two-stage compressor, a high-temperature-stage magnetic suspension two-stage compressor and a plurality of medium heat exchange assemblies. The inlet end of a first one-way valve and the outlet end of a second one-way valve of the one-way valve pipe set of each medium heat exchange assembly communicate with the outlet end of the corresponding condenser, and the inlet end of the second one-way valve and the inlet end of a third one-way valve communicate with the outlet end of the corresponding first main electronic expansion valve and the outlet end of the corresponding second main electronic expansion valve. The outlet end of the third one-way valve and the inlet end of the fourth one-way valve are both communicated with the inlet ends of the corresponding fin evaporators, and the outlet end of the first one-way valve and the outlet end of the fourth one-way valve are both communicated with the inlet ends of the corresponding first main electronic expansion valve and second main electronic expansion valve. The invention has the advantages of reduced pressure ratio, stability, energy conservation, high energy efficiency, low fault rate and accurate throttling.

Description

Technical Field

[0001] The present invention relates to the field of magnetic levitation air energy heat pumps, and particularly to a working method for a dual-head four-stage magnetic levitation air energy heat pump cold and hot water unit. Background Art

[0002] At present, an existing single-stage dual-stage magnetic levitation compressor is used for an air energy (air-cooled) heat pump. Since the pressure ratio of the magnetic levitation compressor is too large when operating at a low ambient temperature and a high water temperature, it is easy for the magnetic levitation compressor to surge. Therefore, the existing technology cannot be used for a magnetic levitation air energy (air-cooled) heat pump. Summary of the Invention

[0003] The purpose of the present invention is to provide a dual-head four-stage magnetic levitation air energy heat pump cold and hot water unit and a working method, which have the advantages of reducing the pressure ratio, being stable, energy-saving, having high energy efficiency, low failure rate, accurate throttling, stable hot water temperature during heating with grouped defrosting without shutdown, and only one compressor operating during refrigeration.

[0004] The above technical purpose of the present invention is achieved through the following technical solutions: A dual-head four-stage magnetic levitation air energy heat pump cold and hot water unit includes a low-temperature stage magnetic levitation two-stage compressor, a high-temperature stage magnetic levitation two-stage compressor, and several medium heat exchange components; The outlet end of the low-temperature stage magnetic levitation two-stage compressor is connected to the inlet end of the high-temperature stage magnetic levitation two-stage compressor, and a first one-way valve is provided at the connection. The inlet end of the first one-way valve is connected to the outlet end of the low-temperature stage magnetic levitation two-stage compressor, and the outlet end of the first one-way valve is connected to the inlet end of the high-temperature stage magnetic levitation two-stage compressor; Each group of medium heat exchange components includes a condenser, a one-way valve pipe group, a first main electronic expansion valve, a second main electronic expansion valve, and a fin evaporator. The first main electronic expansion valve and the second main electronic expansion valve are placed in parallel. The one-way valve pipe group includes a first one-way valve, a second one-way valve, a third one-way valve, and a fourth one-way valve; the inlet end of the first one-way valve and the outlet end of the second one-way valve are both connected to the first outlet end of the corresponding condenser. The inlet end of the second one-way valve and the inlet end of the third one-way valve are both connected to the outlet ends of the corresponding first main electronic expansion valve and second main electronic expansion valve. The outlet end of the third one-way valve and the inlet end of the fourth one-way valve are both connected to the inlet end of the corresponding fin evaporator. The outlet end of the first one-way valve and the outlet end of the fourth one-way valve are both connected to the inlet ends of the corresponding first main electronic expansion valve and second main electronic expansion valve; A four-way valve is provided at the outlet end of each fin evaporator. The outlet end of each fin evaporator is communicated with the second outlet end of its corresponding four-way valve. The first inlet end of each condenser is communicated with the first outlet end of its corresponding four-way valve. The second inlet ends of several four-way valves are communicated, and a gas-liquid separator is provided at the communication point. The outlet end of the gas-liquid separator is communicated with the inlet end of the high-temperature stage magnetic levitation two-stage compressor and the inlet end of the low-temperature stage magnetic levitation two-stage compressor respectively. A second one-way valve is provided between the outlet end of the gas-liquid separator and the inlet end of the high-temperature stage magnetic levitation two-stage compressor. The outlet end of the first one-way valve is communicated with the outlet end of the second one-way valve and the inlet end of the high-temperature stage magnetic levitation two-stage compressor. The outlet end of the high-temperature stage magnetic levitation two-stage compressor is communicated with the first inlet ends of several four-way valves respectively; Two water medium pipelines are provided at the second inlets and second outlets of several condensers.

[0005] The preferred solutions are as follows: Preferably: It further includes a plate heat economizer, an enhanced enthalpy electronic expansion valve, a first three-way joint, and a second three-way joint; The communication point where the outlet end of each first one-way valve, the outlet end of the fourth one-way valve, the inlet end of the first main electronic expansion valve, and the inlet end of the second main electronic expansion valve are communicated is communicated with the first port of the first three-way joint. The second port of the first three-way joint is communicated with the motor cooling and drive cooling port of the high-temperature stage magnetic levitation two-stage compressor. The third port of the first three-way joint is communicated with the first port of the second three-way joint. The second port of the second three-way joint is communicated with the first inlet end of the plate heat economizer. The first outlet end of the plate heat economizer is communicated with the inlet end of the enhanced enthalpy electronic expansion valve. The outlet end of the enhanced enthalpy electronic expansion valve is communicated with the second inlet end of the plate heat economizer. The second outlet end of the plate heat economizer is communicated with the enhanced enthalpy port of the low-temperature stage magnetic levitation two-stage compressor; A second three-way joint is additionally provided at the communication point between the third port of the first three-way joint (20) and the first inlet end of the plate heat economizer. The second three-way joint is communicated with the motor cooling and drive cooling port of the low-temperature stage magnetic levitation two-stage compressor.

[0006] Preferably: A bypass electronic expansion valve is provided between the inlet end of the gas-liquid separator and the outlet end of the high-temperature stage magnetic levitation two-stage compressor. The inlet of the bypass electronic expansion valve is communicated with the first inlet ends of several four-way valves. The outlet of the bypass electronic expansion valve is communicated with the inlet end of the gas-liquid separator.

[0007] The working method of a dual-head four-stage magnetic levitation air source heat pump cold and hot water unit, including a heating mode, a refrigeration mode, a defrosting mode, and a cooling mode; Heating mode: Step 1: The low-temperature-stage magnetic levitation two-stage compressor and the high-temperature-stage magnetic levitation two-stage compressor operate, and the refrigerant heat transfer medium in the double-head four-stage magnetic levitation air source heat pump cold and hot water unit system flows. Step 2: The liquid refrigerant at medium temperature and medium pressure enters the first one-way valve from the condenser. The refrigerant at medium temperature and medium pressure passes through the first one-way valve and enters the first main electronic expansion valve and the second main electronic expansion valve respectively. The first main electronic expansion valve and the second main electronic expansion valve throttle, depressurize, and cool the refrigerant. Subsequently, the formed gaseous refrigerant at low temperature and low pressure enters the third one-way valve. The gaseous refrigerant at low temperature and low pressure that enters the third one-way valve enters the fin evaporator. The gaseous refrigerant at low temperature and low pressure enters the fin evaporator and exchanges heat with the air and evaporates to form a gaseous refrigerant at medium temperature and medium pressure. Step 3: The gaseous refrigerants at medium temperature and medium pressure formed by the fin evaporators of several medium heat exchange components all enter from the second outlet end of their corresponding four-way valves. Subsequently, they go from the second inlet end of several four-way valves to the inlet end of the gas-liquid separator, and finally enter the low-temperature-stage magnetic levitation two-stage compressor for compression from the outlet end of the gas-liquid separator. The gaseous refrigerant at low temperature and low pressure enters the low-temperature-stage magnetic levitation two-stage compressor to form a gaseous refrigerant at high temperature and high pressure. Subsequently, the gaseous refrigerant at high temperature and high pressure passes through the first one-way valve and enters the high-temperature-stage magnetic levitation two-stage compressor to form a gaseous refrigerant at ultra-high temperature and high pressure. At this time, the gaseous refrigerant at high temperature and high pressure presses against the second one-way valve. Step 4: The gaseous refrigerant at ultra-high temperature and high pressure enters the first inlet end of several four-way valves, and then enters the corresponding condensers through the first outlet ends of several four-way valves, exchanges heat with the water medium in the condensers to form a refrigerant at medium temperature and medium pressure. The water medium after heat exchange in the condenser enters the indoor unit for heat exchange through the water medium pipeline. Step 5: Repeat Step 2, Step 3, and Step 4. Refrigeration and defrosting modes: Step 1: The high-temperature-stage magnetic levitation two-stage compressor operates, and the heat transfer medium in the double-head four-stage magnetic levitation air source heat pump cold and hot water unit system flows. Step 2: The gaseous refrigerant at high temperature and high pressure in the high-temperature-stage magnetic levitation two-stage compressor enters the first inlet end of several four-way valves, and respectively enters several fin evaporators through the second outlet ends of several four-way valves to exchange heat with the air to reduce pressure and temperature, forming a liquid refrigerant at medium temperature and medium pressure. The liquid refrigerant at medium temperature and medium pressure enters the fourth one-way valve, passes through the fourth one-way valve and enters the first main electronic expansion valve and the second main electronic expansion valve. The first main electronic expansion valve and the second main electronic expansion valve throttle, depressurize, and cool the refrigerant, turning it into a gaseous refrigerant at low temperature and low pressure. Subsequently, the gaseous refrigerant at low temperature and low pressure enters the second one-way valve. Step 3: The low-temperature and low-pressure gaseous refrigerant enters the corresponding condenser through the second one-way valve and exchanges heat with the water medium in the condenser. After evaporation, it becomes a medium-temperature and medium-pressure gaseous refrigerant. The medium-temperature and medium-pressure gaseous refrigerant enters the first outlet end of the corresponding four-way valve from the condenser. The medium-temperature and medium-pressure gaseous refrigerant enters from the first outlet end of the four-way valve, then enters from the second inlet end to the inlet end of the gas-liquid separator, and finally enters the second one-way valve from the outlet end of the gas-liquid separator. At the same time, it holds the first one-way valve to prevent the medium-temperature and medium-pressure gaseous refrigerant from entering the low-temperature-stage magnetic levitation two-stage compressor. It enters the high-temperature-stage magnetic levitation two-stage compressor for compression. After the medium-temperature and medium-pressure gaseous refrigerant is compressed by the high-temperature-stage magnetic levitation two-stage compressor, it forms a high-temperature and high-pressure gaseous refrigerant; Step 4: Repeat Step 2 to Step 3; Defrosting mode: When the following conditions are simultaneously met: ambient temperature ≤ set defrosting ambient temperature; cumulative operating time of the dual-head four-stage magnetic levitation air-source heat pump cold and hot water unit system ≥ set defrosting interval time, ambient temperature - suction gas temperature ≥ set ambient temperature - suction gas temperature, and the duration ≥ 3 minutes. At this time, the low-temperature-stage magnetic levitation two-stage compressor and the medium heat exchange component enter defrosting; Only two medium heat exchange components in the same group among several medium heat exchange components are allowed to defrost simultaneously. The other medium heat exchange components continue to work. When these two medium heat exchange components complete defrosting and start to enter normal operation, the other two medium heat exchange components in the same group can enter defrosting, and the other systems continue to work; Low-temperature-stage magnetic levitation two-stage compressor enthalpy-increasing and temperature-reducing mode: The medium-temperature and medium-pressure liquid refrigerant enters the plate economizer from the first three-way valve through the second three-way valve and then enters the enthalpy-increasing electronic expansion valve for throttling. The low-temperature and low-pressure liquid refrigerant after throttling by the enthalpy-increasing electronic expansion valve enters the plate economizer again to evaporate into a medium-temperature and medium-pressure gaseous refrigerant and then enters the enthalpy-increasing port of the low-temperature-stage magnetic levitation two-stage compressor. The medium-temperature and medium-pressure liquid refrigerant simultaneously enters the motor cooling and drive cooling port of the low-temperature-stage magnetic levitation two-stage compressor through the third port of the second three-way valve High-temperature-stage magnetic levitation two-stage compressor temperature-reducing mode: The medium-temperature and medium-pressure refrigerant enters the motor cooling and drive cooling port of the high-temperature-stage magnetic levitation two-stage compressor from the first three-way valve.

[0008] In summary, the present invention has the following beneficial effects: 1. Through the series arrangement of the low-temperature-stage magnetic levitation two-stage compressor and the high-temperature-stage magnetic levitation two-stage compressor, it can achieve four-stage compression during heating, the pressure ratio of the magnetic levitation two-stage compressor, and make the magnetic levitation two-stage compressor operate in a more stable and energy-saving state; 2. By setting a number of medium heat exchange components, it can achieve more accurate throttling, better energy-saving effect, and the effect of independent defrosting to make the hot water temperature more stable; 3. By setting the auxiliary electronic expansion valve, it can prevent the low-stage magnetic levitation two-stage compressor and the high-stage magnetic levitation two-stage compressor from surging when the low-stage magnetic levitation two-stage compressor and the high-stage magnetic levitation two-stage compressor are started.

[0009] 4. By setting the enthalpy-increasing electronic expansion valve, it can achieve higher heating capacity at a lower ambient temperature during heating and more stable operation. During cooling, it can achieve higher cooling capacity at a higher ambient temperature and more stable high pressure during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic framework diagram of Embodiment 1; Figure 2 is a schematic framework diagram of the heating mode of Embodiment 1; Figure 3 is a schematic framework diagram of the cooling mode of Embodiment 1; Figure 4 is a schematic framework diagram of the one-way valve group of Embodiment 1 and Embodiment 2; Figure 5 is a schematic framework diagram of Embodiment 2; Figure 6 is a schematic framework diagram of the heating mode of Embodiment 2; Figure 7 is a schematic framework diagram of the cooling mode of Embodiment 2; Figure 8 is a schematic framework diagram of Embodiment 3; Figure 9 is a schematic framework diagram of the heating mode of Embodiment 3; Figure 10 is a schematic framework diagram of the cooling mode of Embodiment 3.

[0011] In the figure, 1. low-stage magnetic levitation two-stage compressor; 2. high-stage magnetic levitation two-stage compressor; 3. medium heat exchange component; 4. No. 1 one-way valve; 5. condenser; 6. one-way valve pipe group; 7. first main electronic expansion valve; 8. second main electronic expansion valve; 9. finned evaporator; 10. first one-way valve; 11. second one-way valve; 12. third one-way valve; 13. fourth one-way valve; 14. four-way valve; 15. gas-liquid separator; 16. No. 2 one-way valve; 17. water medium pipeline; 18. plate-type economizer; 19. enthalpy-increasing electronic expansion valve; 20. first three-way joint; 21. second three-way joint; 22. auxiliary electronic expansion valve; 23. shell-and-tube heat exchanger; 24. third three-way joint. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] The present invention will be further described in detail below with reference to the accompanying drawings.

[0013] Embodiment 1: As Figures 1 - 4 shown, The dual-head four-stage magnetic levitation air-source heat pump cold and hot water unit includes a low-temperature-stage magnetic levitation two-stage compressor 1, a high-temperature-stage magnetic levitation two-stage compressor 2, several medium heat exchange components 3, a plate economizer 18, an enhanced enthalpy electronic expansion valve 19, a first three-way valve 20, and a second three-way valve 21; The outlet end of the low-temperature-stage magnetic levitation two-stage compressor 1 is connected to the inlet end of the high-temperature-stage magnetic levitation two-stage compressor 2, and a first one-way valve 4 is provided at the connection, the inlet end of the first one-way valve 4 is connected to the outlet end of the low-temperature-stage magnetic levitation two-stage compressor 1, and the outlet end of the first one-way valve 4 is connected to the inlet end of the high-temperature-stage magnetic levitation two-stage compressor 2; Each group of medium heat exchange components 3 includes a condenser 5, a one-way valve pipe group 6, a first main electronic expansion valve 7, a second main electronic expansion valve 8, and a finned evaporator 9. The first main electronic expansion valve 7 and the second main electronic expansion valve 8 are placed in parallel. The one-way valve pipe group 6 includes a first one-way valve 10, a second one-way valve 11, a third one-way valve 12, and a fourth one-way valve 13. The inlet end of the first one-way valve 10 and the outlet end of the second one-way valve 11 are both connected to the first outlet end of the corresponding condenser 5. The inlet end of the second one-way valve 11 and the inlet ends of the third one-way valve 12 are both connected to the outlet ends of the corresponding first main electronic expansion valve 7 and second main electronic expansion valve 8. The outlet end of the third one-way valve 12 and the inlet end of the fourth one-way valve 13 are both connected to the inlet end of the corresponding finned evaporator 9. The outlet end of the first one-way valve 10 and the outlet end of the fourth one-way valve 13 are both connected to the inlet ends of the corresponding first main electronic expansion valve 7 and second main electronic expansion valve 8; A four-way valve 14 is provided at the outlet end of each finned evaporator 9. The outlet end of each finned evaporator 9 is connected to the second outlet end of the corresponding four-way valve 14. The first inlet end of each condenser 5 is connected to the first outlet end of the corresponding four-way valve 14. The second inlet ends of several four-way valves 14 are connected and a gas-liquid separator 15 is provided at the connection. The outlet end of the gas-liquid separator 15 is respectively connected to the inlet end of the high-temperature-stage magnetic levitation two-stage compressor 2 and the inlet end of the low-temperature-stage magnetic levitation two-stage compressor 1. A second one-way valve 16 is provided between the outlet end of the gas-liquid separator 15 and the inlet end of the high-temperature-stage magnetic levitation two-stage compressor 2. The outlet end of the first one-way valve 4 is connected to the outlet end of the second one-way valve 16 and the inlet end of the high-temperature-stage magnetic levitation two-stage compressor 2. The outlet end of the high-temperature-stage magnetic levitation two-stage compressor 2 is respectively connected to the first inlet ends of several four-way valves 14; Two water medium pipelines 17 are provided at the second inlets and second outlets of several condensers 5.

[0014] The outlet end of each first one-way valve 10, the outlet end of the fourth one-way valve 13, the inlet end of the first main electronic expansion valve 7, and the inlet end of the second main electronic expansion valve 8 are all connected to the first port of the first three-way joint 20. The second port of the first three-way joint 20 is connected to the motor cooling and drive cooling port of the high-temperature-stage magnetic levitation two-stage compressor 2. The third port of the first three-way joint 20 is connected to the first port of the second three-way joint 21. The second port of the second three-way joint 21 is connected to the first inlet end of the plate-type economizer heat exchanger 18. The first outlet end of the plate-type economizer heat exchanger 18 is connected to the inlet end of the enthalpy-increasing electronic expansion valve 19. The outlet end of the enthalpy-increasing electronic expansion valve 19 is connected to the second inlet end of the plate-type economizer heat exchanger 18. The second outlet end of the plate-type economizer heat exchanger 18 is connected to the enthalpy-increasing port of the low-temperature-stage magnetic levitation two-stage compressor 1; A second three-way joint 21 is additionally provided at the connection between the third port of the first three-way joint 20 and the first inlet end of the plate-type economizer heat exchanger 18. The second three-way joint 21 is connected to the motor cooling and drive cooling port of the low-temperature-stage magnetic levitation two-stage compressor 1.

[0015] A bypass electronic expansion valve 22 is provided between the inlet end of the gas-liquid separator 15 and the outlet end of the high-temperature-stage magnetic levitation two-stage compressor 2. The inlet of the bypass electronic expansion valve 22 is connected to the first inlet ends of a plurality of four-way valves 14. The outlet of the bypass electronic expansion valve 22 is connected to the inlet end of the gas-liquid separator 15.

[0016] The working method of a dual-head four-stage magnetic levitation air-source heat pump cold and hot water unit, including a heating mode, a refrigeration mode, a defrosting mode, and a cooling mode; Heating mode: Step 1: The low-temperature-stage magnetic levitation two-stage compressor 1 and the high-temperature-stage magnetic levitation two-stage compressor 2 operate, and the refrigerant heat exchange medium in the dual-head four-stage magnetic levitation air-source heat pump cold and hot water unit system flows; Step 2: The medium-temperature and medium-pressure liquid refrigerant enters the first one-way valve 10 from the condenser 5. The medium-temperature and medium-pressure refrigerant enters the first main electronic expansion valve 7 and the second main electronic expansion valve 8 respectively through the first one-way valve 10. The first main electronic expansion valve 7 and the second main electronic expansion valve 8 throttle, depressurize, and cool down the refrigerant. Subsequently, the low-temperature and low-pressure gaseous refrigerant enters the third one-way valve 12; The low-temperature and low-pressure gaseous refrigerant entering the third one-way valve 12 enters the fin evaporator 9. The low-temperature and low-pressure gaseous refrigerant enters the fin evaporator 9 and exchanges heat with the air to evaporate and form a medium-temperature and medium-pressure gaseous refrigerant; Step 3: The gaseous refrigerants at medium temperature and medium pressure formed by the fin evaporators 9 of several medium heat exchange components 3 all enter from the second outlet end of their corresponding four-way valves 14, then from the second inlet end of several four-way valves 14 to the inlet end of the gas-liquid separator 15, and finally enter the low-temperature magnetic levitation two-stage compressor 1 from the outlet end of the gas-liquid separator 15 for compression. The gaseous refrigerant at low temperature and low pressure enters the low-temperature magnetic levitation two-stage compressor 1 to form a gaseous refrigerant at high temperature and high pressure. Subsequently, the gaseous refrigerant at high temperature and high pressure enters the high-temperature magnetic levitation two-stage compressor 2 through the first one-way valve 4 to form a gaseous refrigerant at ultra-high temperature and high pressure. At this time, the gaseous refrigerant at high temperature and high pressure presses against the second one-way valve 16; Step 4: The gaseous refrigerant at ultra-high temperature and high pressure enters the first inlet end of several four-way valves 14, and then enters the corresponding condenser 5 through the first outlet end of several four-way valves 14 to exchange heat with the water medium in the condenser 5 to form a refrigerant at medium temperature and medium pressure. The water medium after heat exchange in the condenser 5 enters the indoor unit for heat exchange through the water medium pipeline 17; Step 5: Repeat Step 2, Step 3, and Step 4; Refrigeration and defrosting modes: Step 1: The high-temperature magnetic levitation two-stage compressor 2 operates, and the heat exchange medium in the double-head four-stage magnetic levitation air-source heat pump cold and hot water unit system flows; Step 2: The gaseous refrigerant at high temperature and high pressure in the high-temperature magnetic levitation two-stage compressor 2 enters the first inlet end of several four-way valves 14, and respectively enters several fin evaporators 9 through the second outlet end of several four-way valves 14 to exchange heat with air to reduce pressure and temperature, forming a liquid refrigerant at medium temperature and medium pressure; The liquid refrigerant at medium temperature and medium pressure enters the fourth one-way valve 13, and enters the first main electronic expansion valve 7 and the second main electronic expansion valve 8 through the fourth one-way valve 13. The first main electronic expansion valve 7 and the second main electronic expansion valve 8 throttle, depressurize, and cool the refrigerant to become a gaseous refrigerant at low temperature and low pressure. Subsequently, the gaseous refrigerant at low temperature and low pressure enters the second one-way valve 11; Step 3: The gaseous refrigerant at low temperature and low pressure enters its corresponding condenser 5 through the second one-way valve 11 to exchange heat with the water medium in the condenser 5 and evaporates to become a gaseous refrigerant at medium temperature and medium pressure. The gaseous refrigerant at medium temperature and medium pressure enters the first outlet end of its corresponding four-way valve 14 from the condenser 5. The gaseous refrigerant at medium temperature and medium pressure enters from the first outlet end of the four-way valve 14, then from the second inlet end to the inlet end of the gas-liquid separator 15, and finally enters the second one-way valve 16 from the outlet end of the gas-liquid separator 15. The inlet of the low-temperature magnetic levitation two-stage compressor 1 is closed, and it enters the high-temperature magnetic levitation two-stage compressor 2 from the second one-way valve 16 for compression. The gaseous refrigerant at medium temperature and medium pressure enters the high-temperature magnetic levitation two-stage compressor 2 and is compressed to form a gaseous refrigerant at high temperature and high pressure; Step 4: Repeat Step 2 to Step 3; Defrosting mode: When the following conditions are met simultaneously: ambient temperature ≤ set defrosting ambient temperature; cumulative operating time of the dual-head four-stage magnetic levitation air source heat pump cold and hot water unit system ≥ set defrosting interval time, ambient temperature - suction temperature ≥ set ambient temperature - suction temperature, and the duration ≥ 3 minutes. At this time, the low-temperature stage magnetic levitation double-stage compressor 1 and the medium heat exchange component 3 enter defrosting; Only two medium heat exchange components 3 in the same group among several medium heat exchange components 3 are allowed to defrost simultaneously, and the other medium heat exchange components 3 continue to work. After these two medium heat exchange components 3 complete defrosting and start to enter normal operation, the other two medium heat exchange components 3 in the same group can enter defrosting, and the other systems continue to work; Low-temperature stage magnetic levitation double-stage compressor 1 enthalpy-increasing and temperature-reducing mode: The medium-temperature and medium-pressure liquid refrigerant enters the plate economizer 18 from the first three-way valve 20 and then enters the enthalpy-increasing electronic expansion valve 19 for throttling. The low-temperature and low-pressure liquid refrigerant after throttling by the enthalpy-increasing electronic expansion valve 19 enters the plate economizer 18 again to evaporate into a medium-temperature and medium-pressure gaseous refrigerant and then enters the enthalpy-increasing port of the low-temperature stage magnetic levitation double-stage compressor 1; the medium-temperature and medium-pressure liquid refrigerant simultaneously enters the motor cooling and drive cooling port of the low-temperature stage magnetic levitation double-stage compressor 1 through the second three-way valve 21 High-temperature stage magnetic levitation double-stage compressor 2 temperature-reducing mode: The medium-temperature and medium-pressure refrigerant enters the motor cooling and drive cooling port of the high-temperature stage magnetic levitation double-stage compressor 2 from the first three-way valve 21.

[0017] Embodiment 2: As Figures 4 - 7 shown, The dual-head four-stage magnetic levitation air source heat pump cold and hot water unit includes a low-temperature stage magnetic levitation double-stage compressor 1, a high-temperature stage magnetic levitation double-stage compressor 2, several medium heat exchange components 3, a plate economizer 18, an enthalpy-increasing electronic expansion valve 19, a first three-way valve 20, and a second three-way valve 21; Each group of medium heat exchange components 3 includes a condenser 5, a one-way valve pipe group 6, a first main electronic expansion valve 7, a second main electronic expansion valve 8, and a fin evaporator 9. The first main electronic expansion valve 7 and the second main electronic expansion valve 8 are placed in parallel. The one-way valve pipe group 6 includes a first one-way valve 10, a second one-way valve 11, a third one-way valve 12, and a fourth one-way valve 13. The inlet end of the first one-way valve 10 and the outlet end of the second one-way valve 11 are both connected to the outlet end of the corresponding condenser 5. The inlet end of the second one-way valve 11 and the inlet end of the third one-way valve 12 are both connected to the outlet ends of the corresponding first main electronic expansion valve 7 and the second main electronic expansion valve 8. The outlet end of the third one-way valve 12 and the inlet end of the fourth one-way valve 13 are both connected to the inlet end of the corresponding fin evaporator 9. The outlet end of the first one-way valve 10 and the outlet end of the fourth one-way valve 13 are both connected to the inlet ends of the corresponding first main electronic expansion valve 7 and the second main electronic expansion valve 8. A four-way valve 14 is provided at the outlet end of the low-temperature stage magnetic levitation two-stage compressor 1. The outlet ends of several fin evaporators 9 are all connected to the second outlet end of the four-way valve 14 of the low-temperature stage magnetic levitation two-stage compressor 1. The first inlet end of the four-way valve 14 is connected to the outlet end of the low-temperature stage magnetic levitation two-stage compressor 1. The first outlet end of the four-way valve 14 is connected to the inlet end of the high-temperature stage magnetic levitation two-stage compressor 2. The first inlet ends of several condensers 5 are all connected to the first outlet end of the four-way valve 14. The second inlet end of the four-way valve 14 is connected to the inlet end of the low-temperature stage magnetic levitation two-stage compressor 1. A gas-liquid separator 15 is provided between the second inlet end of the four-way valve 14 and the low-temperature stage magnetic levitation two-stage compressor 1. The first outlet end of the four-way valve 14 is also simultaneously connected to the inlet end of the high-temperature stage magnetic levitation two-stage compressor 2. A first one-way valve 4 is provided at the outlet end of the high-temperature stage magnetic levitation two-stage compressor 2. The outlet end of the first one-way valve 4 is also simultaneously respectively connected to the first inlet ends of several condensers 5. A second one-way valve 16 is provided between the first outlet end of the four-way valve 14 and the first inlet ends of several condensers 5. The outlet end of the second one-way valve 16 is connected to the first outlet end of the four-way valve 14. The second inlets and second outlets of several condensers 5 are connected in parallel by two water medium pipelines 17.

[0018] The outlet end of each first one-way valve 10, the outlet end of the fourth one-way valve 13, the inlet end of the first main electronic expansion valve 7, and the inlet end of the second main electronic expansion valve 8 are all connected to the first port of the first three-way joint 20. The third port of the first three-way joint 20 is connected to the first port of the second three-way joint. The second port of the second three-way joint 20 is connected to the first inlet end of the plate-type economizer heat exchanger 18. The motor cooling and drive cooling port of the high-temperature stage magnetic levitation two-stage compressor 2 is connected to the second end of the first three-way joint 20. The first outlet end of the plate-type economizer heat exchanger 18 is connected to the inlet end of the enthalpy-increasing electronic expansion valve 19. The outlet end of the enthalpy-increasing electronic expansion valve 19 is connected to the enthalpy-increasing port of the low-temperature stage magnetic levitation two-stage compressor 1. A second three-way joint 21 is additionally provided at the connection between the third port of the first three-way joint 20 near the high-temperature stage magnetic levitation two-stage compressor 2 and the first inlet end of the plate-type economizer heat exchanger 18. The third port of the second three-way joint 21 is connected to the motor cooling and drive cooling port of the low-temperature stage magnetic levitation two-stage compressor 1.

[0019] A bypass electronic expansion valve 22 is also provided in parallel with several medium heat exchange assemblies 3.

[0020] The working method of the double-head four-stage magnetic levitation air-source heat pump cold and hot water unit includes a heating mode, a refrigeration mode, a defrosting mode, and a cooling mode. Heating mode: Step 1: The low-temperature stage magnetic levitation two-stage compressor 1 and the high-temperature stage magnetic levitation two-stage compressor 2 work, and the refrigerant heat exchange medium in the double-head four-stage magnetic levitation air-source heat pump cold and hot water unit system flows. Step 2: The medium-temperature and medium-pressure refrigerant enters the first one-way valve 10 from the condenser 5. The medium-temperature and medium-pressure refrigerant enters the first main electronic expansion valve 7 and the second main electronic expansion valve 8 respectively through the first one-way valve 10. The first main electronic expansion valve 7 and the second main electronic expansion valve 8 throttle, depressurize, and cool the refrigerant, and then form a low-temperature and low-pressure gaseous refrigerant and enter the third one-way valve 12. The low-temperature and low-pressure gaseous refrigerant entering the third one-way valve 12 enters the fin evaporator 9. The low-temperature and low-pressure gaseous refrigerant enters the fin evaporator 9 and exchanges heat with air and evaporates to form a medium-temperature and medium-pressure gaseous refrigerant. Step 3: The medium-temperature and medium-pressure gaseous refrigerant formed in the fin evaporators 9 of several medium heat exchange assemblies 3 all enters from the second outlet end of the four-way valve 14, then from the second inlet end of the four-way valve 14 to the inlet end of the gas-liquid separator 15, and finally enters the low-temperature stage magnetic levitation two-stage compressor 1 from the outlet end of the gas-liquid separator 15 for compression. The low-temperature and low-pressure gaseous refrigerant enters the low-temperature stage magnetic levitation two-stage compressor 1 and is compressed to form a high-temperature and high-pressure gaseous refrigerant. Then, the high-temperature and high-pressure gaseous refrigerant enters the high-temperature stage magnetic levitation two-stage compressor 2 through the first outlet end of the four-way valve 14 to form an ultra-high-temperature and high-pressure gaseous refrigerant. Step 4: The superheated and superpressurized gaseous refrigerant enters several condensers 5 through the first one-way valve 4 to exchange heat with the water medium in the condensers 5, forming a refrigerant with medium temperature and medium pressure. Step 5: Repeat Step 2, Step 3, and Step 4. Refrigeration mode: Step 1: The low-temperature stage magnetic levitation two-stage compressor 1 operates, and the refrigerant medium in the double-head four-stage magnetic levitation air source heat pump cold and hot water unit system flows. Step 2: The high-temperature and high-pressure gaseous refrigerant enters several finned evaporators 9 through the second inlet end of the four-way valve 14 to exchange heat with the air to reduce pressure and temperature, forming a medium-temperature and medium-pressure liquid refrigerant. Subsequently, the refrigerant enters the fourth one-way valve 13, passes through the fourth one-way valve 13 and enters the first main electronic expansion valve 7 and the second main electronic expansion valve 8. The first main electronic expansion valve 7 and the second main electronic expansion valve 8 throttle, depressurize, and cool the refrigerant, turning it into a low-temperature and low-pressure gaseous refrigerant. Subsequently, the low-temperature and low-pressure gaseous refrigerant enters the second one-way valve 11. Step 3: The low-temperature and low-pressure gaseous refrigerant enters the condenser 5 through the second one-way valve 11 to exchange heat with the water medium in the condenser 5, evaporates and becomes a medium-temperature and medium-pressure gaseous refrigerant. The medium-temperature and medium-pressure gaseous refrigerant enters the condenser 5 and then enters the second one-way valve 16. The medium-temperature and medium-pressure gaseous refrigerant enters from the first outlet end of the four-way valve 14, then enters from the second inlet end to the inlet end of the gas-liquid separator 15, and finally enters the low-temperature stage magnetic levitation two-stage compressor 1 for compression from the outlet end of the gas-liquid separator 15. The medium-temperature and medium-pressure gaseous refrigerant forms a high-temperature and high-pressure gaseous refrigerant after being compressed in the low-temperature stage magnetic levitation two-stage compressor 1. Step 4: Repeat Step 2 to Step 3. Defrosting mode: When the following conditions are simultaneously met: ambient temperature ≤ set defrosting ambient temperature; the cumulative operating time of the double-head four-stage magnetic levitation air source heat pump cold and hot water unit system ≥ set defrosting interval time, ambient temperature - return air temperature ≥ set ambient temperature - return air temperature, and the duration ≥ 3 minutes. At this time, the low-temperature stage magnetic levitation two-stage compressor 1 and the medium heat exchange assembly 3 enter defrosting. Only two sets of the medium heat exchange assemblies 3 in the same group among several medium heat exchange assemblies 3 are allowed to defrost simultaneously, and the other medium heat exchange assemblies 3 continue to operate. When these two sets of medium heat exchange assemblies 3 complete defrosting and start to enter normal operation, the other two sets of medium heat exchange assemblies 3 in the same group can enter defrosting, and the other systems continue to operate. Low-temperature stage magnetic levitation two-stage compressor 1 enthalpy increase and temperature reduction mode: The medium-temperature and medium-pressure liquid refrigerant enters the plate economizer heat exchanger 18 from the first three-way valve 20 and then enters the enthalpy-increasing electronic expansion valve 19 for throttling. At the same time, it enters the motor cooling and drive cooling ports of the low-temperature-stage magnetic levitation two-stage compressor 1 through the second three-way valve 21. The low-temperature and low-pressure gaseous refrigerant after throttling by the enthalpy-increasing electronic expansion valve 19 enters the plate economizer heat exchanger 18 again to evaporate into a medium-temperature and medium-pressure gaseous refrigerant, and then enters the enthalpy-increasing port of the low-temperature-stage magnetic levitation two-stage compressor 1; Cooling mode of the high-temperature-stage magnetic levitation two-stage compressor 2: The medium-temperature and medium-pressure refrigerant enters the motor cooling and drive cooling ports of the high-temperature-stage magnetic levitation two-stage compressor 2 from the first three-way valve 21.

[0021] Embodiment 3: As Figures 8 - 10 shown, The dual-head four-stage magnetic levitation air-source heat pump water chiller includes a low-temperature-stage magnetic levitation two-stage compressor 1, a high-temperature-stage magnetic levitation two-stage compressor 2, a shell-and-tube heat exchanger 23, a first main electronic expansion valve 7, a plurality of finned evaporators 9, and a four-way valve 14; A plurality of finned evaporators 9 are connected in parallel; The first inlet end of the four-way valve 14 is connected to the outlet end of the low-temperature-stage magnetic levitation two-stage compressor 1. The outlet ends of the plurality of finned evaporators 9 are connected to the second outlet end of the four-way valve 14. A gas-liquid separator 15 is provided at the second inlet end of the four-way valve 14. The outlet end of the gas-liquid separator 15 is connected to the inlet end of the low-temperature-stage magnetic levitation two-stage compressor 1. The first outlet end of the four-way valve 14 is connected to the inlet end of the high-temperature-stage magnetic levitation two-stage compressor 2; A first one-way valve 4 is provided at the outlet end of the high-temperature-stage magnetic levitation two-stage compressor 2. The outlet end of the first one-way valve 4 is connected to the inlet end of the shell-and-tube heat exchanger 23. A first three-way valve 20 and a first main electronic expansion valve 7 are provided at the outlet end of the shell-and-tube heat exchanger 23. The second port of the first three-way valve 20 is connected to the first main electronic expansion valve 7. The first main electronic expansion valve 7 is connected in parallel with the inlet ends of the plurality of finned evaporators 9; A second one-way valve 16 is further provided at the inlet end of the shell-and-tube heat exchanger 23. The outlet end of the second one-way valve 16 is connected to the first outlet end of the four-way valve 14.

[0022] It further includes a plate economizer heat exchanger 18, an enthalpy-increasing electronic expansion valve 19, a second three-way valve 21, and a third three-way valve 24; The third port of the third three-way valve 24 is connected to the motor cooling and drive cooling ports of the low-temperature-stage magnetic levitation two-stage compressor 1; The third port of the second three-way joint 21 is connected to the first inlet of the plate-type economizer heat exchanger 18. The first outlet end of the plate-type economizer heat exchanger 18 is connected to the inlet end of the enthalpy-increasing electronic expansion valve 19. The outlet end of the enthalpy-increasing electronic expansion valve 19 is connected to the second inlet of the plate-type economizer heat exchanger 18. The second outlet of the plate-type economizer heat exchanger 18 is connected to the enthalpy-increasing port of the low-temperature-stage magnetic levitation two-stage compressor 1. The second port of the third three-way valve 24 is connected to the motor cooling and drive cooling port of the high-temperature-stage magnetic levitation two-stage compressor 2.

[0023] A bypass electronic expansion valve 22 is provided between the inlet end of the shell-and-tube heat exchanger 23 and the outlet ends of a plurality of finned evaporators 9.

[0024] The working method of the dual-head four-stage magnetic levitation air-source heat pump cold and hot water unit includes a heating mode, a refrigeration mode, a defrosting mode, and a cooling mode; Heating mode: Step 1: The low-temperature-stage magnetic levitation two-stage compressor 1 and the high-temperature-stage magnetic levitation two-stage compressor 2 operate, and the refrigerant medium in the dual-head four-stage magnetic levitation air-source heat pump cold and hot water unit system flows. Step 2: The medium-temperature and medium-pressure liquid refrigerant enters the first main electronic expansion valve 7 from the outlet end of the shell-and-tube heat exchanger 23 to throttle, depressurize, and cool the refrigerant. Subsequently, the low-temperature and low-pressure gaseous refrigerant formed after throttling, depressurizing, and cooling enters the finned evaporator 9. The low-temperature and low-pressure gaseous refrigerant enters the finned evaporator 9 and exchanges heat with air to evaporate and form a medium-temperature and medium-pressure gaseous refrigerant. Step 3: The medium-temperature and medium-pressure gaseous refrigerant formed by a plurality of finned evaporators 9 enters from the second outlet end of the four-way valve 14. Subsequently, it goes from the second inlet end of the four-way valve 14 to the inlet end of the gas-liquid separator 15. Finally, it enters the low-temperature-stage magnetic levitation two-stage compressor 1 from the outlet end of the gas-liquid separator 15 for compression. The low-temperature and low-pressure gaseous refrigerant enters the low-temperature-stage magnetic levitation two-stage compressor 1 and is compressed to form a high-temperature and high-pressure gaseous refrigerant. Subsequently, the high-temperature and high-pressure gaseous refrigerant passes through the first inlet end of the four-way valve 14 and then through the first outlet end. Subsequently, it enters the high-temperature-stage magnetic levitation two-stage compressor 2 from the first outlet end of the four-way valve 14 and is compressed again to form an ultra-high-temperature and high-pressure gaseous refrigerant. Step 4: The ultra-high-temperature and high-pressure gaseous refrigerant enters the first one-way valve 4, and then enters the shell-and-tube heat exchanger 23 through the first one-way valve 4 for heat exchange to form a medium-temperature and medium-pressure liquid refrigerant. Step 5: Repeat Step 2, Step 3, and Step 4; Step 6: In the heating mode under relatively low ambient temperature conditions, starting the enthalpy increase can increase the heating capacity by 10 - 20; Refrigeration and defrosting modes: Step 1: The low-temperature-stage magnetic levitation two-stage compressor 1 operates, and the refrigerant medium in the double-head four-stage magnetic levitation air source heat pump cold and hot water unit system flows. Step 2: The high-temperature and high-pressure gaseous refrigerant in the low-temperature-stage magnetic levitation two-stage compressor 1 enters the first inlet end of the four-way valve 14, and then enters several finned evaporators 9 through the second outlet end of the four-way valve 14 to exchange heat with air to reduce pressure and temperature, forming a medium-temperature and medium-pressure liquid refrigerant. Subsequently, the medium-temperature and medium-pressure liquid refrigerant enters the first main electronic expansion valve 7, and the first main electronic expansion valve 7 throttles, reduces pressure, and cools the refrigerant, turning it into a low-temperature and low-pressure gaseous refrigerant. Subsequently, the low-temperature and low-pressure gaseous refrigerant enters the shell-and-tube heat exchanger 23 to exchange heat with the water medium, cool down and evaporate, forming a medium-temperature and medium-pressure gaseous refrigerant.

[0025] The medium-temperature and medium-pressure liquid refrigerant also simultaneously exits from the third port of the first three-way valve 20, passes through the second three-way valve 21, and enters the third three-way valve 24 to enter the defrosting mode. The medium-temperature and medium-pressure liquid refrigerant enters the motor cooling and drive cooling port of the low-temperature-stage magnetic levitation two-stage compressor 1 through the third port of the third three-way valve 24. When the enthalpy-increasing electronic expansion valve 19 is opened under the condition of relatively high refrigeration ambient temperature, the medium-temperature and medium-pressure liquid refrigerant enters the plate-type economizer 18 through the third port of the second three-way valve 21 and is throttled by the enthalpy-increasing electronic expansion valve 19. The low-temperature and low-pressure gaseous refrigerant after throttling by the enthalpy-increasing electronic expansion valve 19 enters the plate-type economizer 18 again to evaporate and become a medium-temperature and medium-pressure gaseous refrigerant, and then enters the enthalpy-increasing port of the low-temperature-stage magnetic levitation two-stage compressor 1. Step 3: The medium-temperature and medium-pressure gaseous refrigerant enters the second one-way valve 16 from the outlet end of the shell-and-tube heat exchanger 23, and then enters the first outlet end of the four-way valve 14 from the outlet end of the second one-way valve 16. The medium-temperature and medium-pressure gaseous refrigerant enters from the first outlet end of the four-way valve 14, then enters from the second inlet end to the inlet end of the gas-liquid separator 15, and finally enters the low-temperature-stage magnetic levitation two-stage compressor 1 from the outlet end of the gas-liquid separator 15 for compression. The medium-temperature and medium-pressure gaseous refrigerant forms a high-temperature and high-pressure gaseous refrigerant after being compressed in the low-temperature-stage magnetic levitation two-stage compressor 1. Step 4: Repeat Step 2 to Step 3. Defrosting mode: When the following conditions are simultaneously met: ambient temperature ≤ set defrosting ambient temperature; the cumulative operation time of the double-head four-stage magnetic levitation air source heat pump cold and hot water unit system ≥ set defrosting interval time, ambient temperature - suction temperature ≥ set difference between ambient temperature and suction temperature, and the duration ≥ 3 minutes, at this time, the low-temperature-stage double-head four-stage magnetic levitation air source heat pump cold and hot water unit system enters defrosting.

[0026] This specific embodiment is only an interpretation of the present invention and is not a limitation thereof. After reading this specification, those skilled in the art may make modifications to this embodiment that do not contribute creatively as needed, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. Double-head four-stage magnetic levitation air source heat pump cold and hot water unit, characterized in that: It includes a low-temperature-stage magnetic levitation two-stage compressor (1), a high-temperature-stage magnetic levitation two-stage compressor (2), and several medium heat exchange components (3); The outlet end of the low-temperature-stage magnetic levitation two-stage compressor (1) is connected to the inlet end of the high-temperature-stage magnetic levitation two-stage compressor (2), and a first one-way valve (4) is provided at the connection. The inlet end of the first one-way valve (4) is connected to the outlet end of the low-temperature-stage magnetic levitation two-stage compressor (1), and the outlet end of the first one-way valve (4) is connected to the inlet end of the high-temperature-stage magnetic levitation two-stage compressor (2); Each group of medium heat exchange components (3) includes a condenser (5), a one-way valve pipe group (6), a first main electronic expansion valve (7), a second main electronic expansion valve (8), and a finned evaporator (9). The first main electronic expansion valve (7) and the second main electronic expansion valve (8) are placed in parallel. The one-way valve pipe group (6) includes a first one-way valve (10), a second one-way valve (11), a third one-way valve (12), and a fourth one-way valve (13). The inlet end of the first one-way valve (10) and the outlet end of the second one-way valve (11) are both connected to the first outlet end of the corresponding condenser (5). The inlet end of the second one-way valve (11) and the inlet ends of the third one-way valve (12) are both connected to the outlet ends of the corresponding first main electronic expansion valve (7) and second main electronic expansion valve (8). The outlet end of the third one-way valve (12) and the inlet end of the fourth one-way valve (13) are both connected to the inlet end of the corresponding finned evaporator (9). The outlet end of the first one-way valve (10) and the outlet end of the fourth one-way valve (13) are both connected to the inlet ends of the corresponding first main electronic expansion valve (7) and second main electronic expansion valve (8); A four-way valve (14) is provided at the outlet end of each finned evaporator (9). The outlet end of each finned evaporator (9) is connected to the second outlet end of the corresponding four-way valve (14). The first inlet end of each condenser (5) is connected to the first outlet end of the corresponding four-way valve (14). The second inlet ends of several four-way valves (14) are connected and a gas-liquid separator (15) is provided at the connection. The outlet end of the gas-liquid separator (15) is respectively connected to the inlet end of the high-temperature-stage magnetic levitation two-stage compressor (2) and the inlet end of the low-temperature-stage magnetic levitation two-stage compressor (1). A second one-way valve (16) is provided between the outlet end of the gas-liquid separator (15) and the inlet end of the high-temperature-stage magnetic levitation two-stage compressor (2). The outlet end of the first one-way valve (4) is connected to the outlet end of the second one-way valve (16) and the inlet end of the high-temperature-stage magnetic levitation two-stage compressor (2). The outlet end of the high-temperature-stage magnetic levitation two-stage compressor (2) is respectively connected to the first inlet ends of several four-way valves (14); Two water medium pipelines (17) are provided at the second inlet and second outlet of several condensers (5).

2. The dual-head four-stage magnetic levitation air source heat pump cold and hot water unit according to claim 1, characterized in that: It further includes a plate-type economizer (18), an enhanced enthalpy electronic expansion valve (19), a first three-way joint (20), and a second three-way joint (21); The outlet end of each first check valve (10), the outlet end of the fourth check valve (13), the inlet end of the first main electronic expansion valve (7), and the inlet end of the second main electronic expansion valve (8) are all connected to the first port of the first three-way joint (20). The second port of the first three-way joint (20) is connected to the motor cooling and drive cooling port of the high-temperature stage magnetic levitation two-stage compressor (2). The third port of the first three-way joint (20) is connected to the first port of the second three-way joint (21). The second port of the second three-way joint (21) is connected to the first inlet end of the plate heat economizer (18). The first outlet end of the plate heat economizer (18) is connected to the inlet end of the enthalpy-increasing electronic expansion valve (19). The outlet end of the enthalpy-increasing electronic expansion valve (19) is connected to the second inlet end of the plate heat economizer (18). The second outlet end of the plate heat economizer (18) is connected to the enthalpy-increasing port of the low-temperature stage magnetic levitation two-stage compressor (1). A second three-way joint (21) is additionally provided at the connection between the third port of the first three-way joint (20) and the first inlet end of the plate heat economizer (18). The second three-way joint (21) is connected to the motor cooling and drive cooling port of the low-temperature stage magnetic levitation two-stage compressor (1).

3. The dual-head four-stage magnetic levitation air source heat pump cold and hot water unit according to claim 2, wherein: A bypass electronic expansion valve (22) is provided between the inlet end of the gas-liquid separator (15) and the outlet end of the high-temperature stage magnetic levitation two-stage compressor (2). The inlet of the bypass electronic expansion valve (22) is connected to the first inlet ends of a number of four-way valves (14). The outlet of the bypass electronic expansion valve (22) is connected to the inlet end of the gas-liquid separator (15).

4. A working method of a dual-head four-stage magnetic levitation air-source heat pump cold and hot water unit, which is used for the dual-head four-stage magnetic levitation air-source heat pump cold and hot water unit as described in claim 3, and is characterized in that: It includes a heating mode, a refrigeration mode, a defrosting mode, and a cooling mode; Heating mode: Step 1: The low-temperature stage magnetic levitation two-stage compressor (1) and the high-temperature stage magnetic levitation two-stage compressor (2) operate, and the refrigerant heat exchange medium in the dual-head four-stage magnetic levitation air-source heat pump cold and hot water unit system flows; Step 2: The medium-temperature and medium-pressure liquid refrigerant enters the first check valve (10) from the condenser (5). The medium-temperature and medium-pressure refrigerant enters the first main electronic expansion valve (7) and the second main electronic expansion valve (8) respectively through the first check valve (10). The first main electronic expansion valve (7) and the second main electronic expansion valve (8) throttle, depressurize, and cool down the refrigerant. Subsequently, the formed low-temperature and low-pressure gaseous refrigerant enters the third check valve (12); The low-temperature and low-pressure gaseous refrigerant entering the third check valve (12) enters the fin evaporator (9). The low-temperature and low-pressure gaseous refrigerant enters the fin evaporator (9) to exchange heat with the air and evaporates to form a medium-temperature and medium-pressure gaseous refrigerant; Step 3: The gaseous refrigerants at medium temperature and medium pressure formed by the fin evaporators (9) of several medium heat exchange components (3) all enter from the second outlet end of their corresponding four-way valves (14), then from the second inlet end of several four-way valves (14) to the inlet end of the gas-liquid separator (15), and finally enter the low-temperature stage magnetic levitation two-stage compressor (1) for compression from the outlet end of the gas-liquid separator (15). The low-temperature and low-pressure gaseous refrigerant enters the low-temperature stage magnetic levitation two-stage compressor (1) to form a high-temperature and high-pressure gaseous refrigerant. Subsequently, the high-temperature and high-pressure gaseous refrigerant passes through the first one-way valve (4) and enters the high-temperature stage magnetic levitation two-stage compressor (2) to form an ultra-high-temperature and high-pressure gaseous refrigerant. At this time, the high-temperature and high-pressure gaseous refrigerant presses against the second one-way valve (16); Step 4: The ultra-high-temperature and high-pressure gaseous refrigerant enters the first inlet end of several four-way valves (14), and then enters the corresponding condenser (5) through the first outlet end of several four-way valves (14), exchanges heat with the water medium in the condenser (5) to form a refrigerant at medium temperature and medium pressure. The water medium after heat exchange in the condenser (5) enters the indoor unit for heat exchange through the water medium pipeline (17); Step 5: Repeat Step 2, Step 3, and Step 4; Refrigeration and defrosting modes: Step 1: The high-temperature stage magnetic levitation two-stage compressor (2) operates, and the heat exchange medium in the double-head four-stage magnetic levitation air source heat pump cold and hot water unit system flows; Step 2: The high-temperature and high-pressure gaseous refrigerant in the high-temperature stage magnetic levitation two-stage compressor (2) enters the first inlet end of several four-way valves (14), and respectively enters several fin evaporators (9) through the second outlet end of several four-way valves (14) to exchange heat with air to reduce pressure and temperature, forming a liquid refrigerant at medium temperature and medium pressure; The liquid refrigerant at medium temperature and medium pressure enters the fourth one-way valve (13), passes through the fourth one-way valve (13) and enters the first main electronic expansion valve (7) and the second main electronic expansion valve (8). The first main electronic expansion valve (7) and the second main electronic expansion valve (8) throttle, depressurize, and cool the refrigerant, turning it into a low-temperature and low-pressure gaseous refrigerant. Subsequently, the low-temperature and low-pressure gaseous refrigerant enters the second one-way valve (11); Step 3: The low-temperature and low-pressure gaseous refrigerant passes through the second one-way valve (11) and enters its corresponding condenser (5) to exchange heat with the water medium in the condenser (5), evaporates and becomes a gaseous refrigerant at medium temperature and medium pressure. The gaseous refrigerant at medium temperature and medium pressure enters the first outlet end of its corresponding four-way valve (14) from the condenser (5). The gaseous refrigerant at medium temperature and medium pressure enters from the first outlet end of the four-way valve (14), then from the second inlet end to the inlet end of the gas-liquid separator (15), and finally enters the second one-way valve (16) from the outlet end of the gas-liquid separator (15). At the same time, it presses against the first one-way valve to prevent the gaseous refrigerant at medium temperature and medium pressure from entering the low-temperature stage magnetic levitation two-stage compressor (1). It enters the high-temperature stage magnetic levitation two-stage compressor (2) for compression from the second one-way valve (16). The gaseous refrigerant at medium temperature and medium pressure is compressed in the high-temperature stage magnetic levitation two-stage compressor (2) to form a high-temperature and high-pressure gaseous refrigerant; Step 4: Repeat Step 2 to Step 3; Defrosting mode: When the following conditions are simultaneously met: the ambient temperature ≤ the set defrost entry ambient temperature; the cumulative operating time of the dual-head four-stage magnetic levitation air source heat pump cold and hot water unit system ≥ the set defrost interval time, the ambient temperature - the suction gas temperature ≥ the set ambient temperature - the suction gas temperature, and the duration ≥ 3 minutes. At this time, the low-temperature stage magnetic levitation two-stage compressor (1) and the medium heat exchange component (3) enter defrosting; Only two medium heat exchange components (3) in the same group among several medium heat exchange components (3) are allowed to defrost simultaneously, and the other medium heat exchange components (3) continue to work. When these two medium heat exchange components (3) complete defrosting and start to enter normal operation, the other two medium heat exchange components (3) in the same group can enter defrosting, and the other systems continue to work; The enthalpy increase and temperature reduction mode of the low-temperature stage magnetic levitation two-stage compressor (1): The liquid refrigerant at medium temperature and medium pressure enters the plate economizer (18) from the first three-way valve (20) through the second three-way valve (20), then enters the enthalpy-increasing electronic expansion valve (19) for throttling. The liquid refrigerant at low temperature and low pressure after throttling by the enthalpy-increasing electronic expansion valve (19) enters the plate economizer (18) again to evaporate into a gaseous refrigerant at medium temperature and medium pressure, and then enters the enthalpy-increasing port of the low-temperature stage magnetic levitation two-stage compressor (1); the liquid refrigerant at medium temperature and medium pressure simultaneously enters the motor cooling and drive cooling port of the low-temperature stage magnetic levitation two-stage compressor (1) through the third port of the second three-way valve (21). The temperature reduction mode of the high-temperature stage magnetic levitation two-stage compressor (2): The refrigerant at medium temperature and medium pressure enters the motor cooling and drive cooling port of the high-temperature stage magnetic levitation two-stage compressor (2) from the first three-way valve (21).

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