Low-temperature air source heat pump unit

Abstract

The application discloses a low-temperature air source heat pump unit, which comprises a box body, a plurality of air guide tubes are symmetrically arranged on the top of the box body, an exhaust fan is arranged in the air guide tube, an electric heating wire is arranged around the inside of the air guide tube, a winding device is arranged in the box body, a distribution box is arranged at the lower part of the front end of the box body, a horizontal supporting rod is arranged on the left side of the bottom of the box body, a first gas-liquid separator, a first compressor, a second compressor and a tube-shell heat exchanger are sequentially arranged on the horizontal supporting rod from the front end to the rear end, a spherical tube-shell heat exchanger, a third compressor, a high-pressure liquid storage tank, a second gas-liquid separator and a brazed plate heat exchanger are sequentially arranged on the horizontal supporting rod from the rear end to the front end. The application has the beneficial effects that the problem of heat pump heating capacity decline or even damage to the evaporator caused by external frost is avoided, the stability of system operation is ensured through the air adding device, the electromagnetic valve is opened when the pressure is insufficient, the problem of damage to the evaporator during operation caused by insufficient system pressure is avoided, and high-quality heat energy is provided.

Description

Technical Field

[0001] This invention relates to the technical field of heat pump units, specifically a low-temperature air source heat pump unit. Background Technology

[0002] When the outdoor temperature is low and the relative humidity is high in winter, the air source heat pump often operates under frosting conditions. When the heat pump performs reverse circulation defrosting, the indoor temperature will drop, affecting the thermal comfort of the indoor environment. Moreover, operating at low temperatures will lead to a decrease in suction pressure, suction temperature, and heating capacity, until the heat pump system can no longer continue to operate. Therefore, enhancing heating capacity has become an urgent requirement for low-temperature air source heat pumps. Summary of the Invention

[0003] To address the above shortcomings, the present invention provides the following technical solution: A low-temperature air source heat pump unit includes a housing. Several air ducts are symmetrically arranged on the top of the housing, each containing an exhaust fan. Heating wires are wound around the inside of each air duct. Ventilation windows are provided around the upper perimeter of the housing, each containing a grid. A winding device is provided on the inner side of each ventilation window. An electrical distribution box is located at the lower front of the housing. An inlet pipe and an outlet pipe are located at the rear of the housing. A base frame is located at the bottom of the housing. Two longitudinal support rods are arranged on both sides of the base frame. Several transverse support rods are arranged between the longitudinal support rods and the sides of the base frame at the bottom of the housing, forming two rows. On the side column of the transverse support rods, from front to rear, are arranged a No. 1 gas-liquid separator, a No. 1 compressor, a No. 2 compressor, and a shell-and-tube heat exchanger. On the right column of the transverse support rods, from rear to front, are arranged a spiral tube shell-and-tube heat exchanger, a No. 3 compressor, a high-pressure liquid storage tank, a No. 2 gas-liquid separator, and a brazed plate heat exchanger. Support frames are provided on the back of the distribution box and on the base frame at the other end of the box. An air duct is provided at the center of the top of the support frame. The top of the air duct has an inverted V-shaped structure. The two sides of the inverted V-shaped structure of the air duct are provided with mounting frames to form an upward V-shaped structure. An evaporator is provided inside the mounting frames.

[0004] Furthermore, the winding device includes several winding motors at the top of the ventilation window. A take-up wheel is provided on the rotating shaft of each winding motor. A traction line is provided on the take-up wheel. A connecting rod is connected to the traction line. A groove is provided at the bottom of the connecting rod. A sealing cloth is provided in the groove. The sealing cloth is PVC coated cloth or PU coated cloth. The sealing cloth is placed on the roll. Both ends of the roll are located in the housing, and motors corresponding to the roll are also provided on the housing at both ends of the roll.

[0005] Furthermore, the heat dissipation pipes within the evaporator in the mounting frame are configured as several parallel heat dissipation pipe structures. One side of each parallel heat dissipation pipe structure has a row of liquid distribution copper pipes and a row of manifold copper pipes. The manifold copper pipes are all connected in parallel and then merged to connect to a four-way valve. The four-way valve then connects to the first gas-liquid separator. The first gas-liquid separator is connected to the first compressor and the second compressor via parallel pipes. These pipes are then merged and connected to the four-way valve. The four-way valve then connects to a shell-and-tube heat exchanger. The shell-and-tube heat exchanger is connected to the... The heat medium inlet of the brazed plate heat exchanger is connected to the high-pressure liquid storage tank. The high-pressure liquid storage tank is then connected to the first electronic expansion valve via a pipeline. A copper filter is installed on the pipeline behind the first electronic expansion valve. The pipeline then splits into two parallel pipelines, each with an evaporator distributor head at its top. The evaporator distributor head distributes liquid through a pipeline to the distributor copper pipe, which then flows into the parallel heat dissipation pipeline structure of the evaporator. The liquid then flows back through the parallel manifold copper pipe, connecting to the four-way valve to form a circulation loop.

[0006] Furthermore, the transverse support rod is a transversely open channel steel structure with several fixing holes on both sides of the channel steel. Several mounting plates are provided between the transverse support rods and are fixed to the transverse support rods by screws and nuts in conjunction with the fixing holes. The mounting plates are used to fix the No. 1 gas-liquid separator, the No. 1 compressor, the No. 2 compressor, the shell-and-tube heat exchanger, the spiral tube shell-and-tube heat exchanger, the No. 3 compressor, the high-pressure liquid storage tank, the No. 2 gas-liquid separator, and the brazed plate heat exchanger.

[0007] Furthermore, a fixing plate is provided at the top right corner of the support frame on one side of the distribution box. A fan is provided on the fixing plate. An air inlet bend is provided at the bottom of the fan and connected to the outside of the box for connecting to the solar hot air pipe. A guide plate in the shape of an inverted right-angle trapezoid is connected to the pipe on the side of the fan. The opening of the guide plate is connected to one end of the air duct. Several round holes are evenly provided at the bottom of the air duct. Ear-shaped air outlets with downward openings are provided on both sides of the air duct.

[0008] Furthermore, the refrigerant outlet pipe of the brazed plate heat exchanger is connected to the No. 2 gas-liquid separator, the No. 2 gas-liquid separator pipe is connected to the No. 3 compressor, the No. 3 compressor pipe is connected to the spiral tube shell-and-tube heat exchanger, and the spiral tube shell-and-tube heat exchanger is again connected to the No. 2 electronic expansion valve through a pipe and then connected to the refrigerant inlet of the brazed plate heat exchanger to form a complete two-stage heating circuit.

[0009] Furthermore, the spiral tube shell-and-tube heat exchanger and the shell-and-tube heat exchanger are provided with two spiral tubes of different diameters arranged in parallel on the same axis and in the same direction. The water inlets of the spiral tubes of the spiral tube shell-and-tube heat exchanger and the shell-and-tube heat exchanger are located on the inner bottom side and are arranged opposite each other and connected in parallel to the water inlet pipe. The water outlets of the spiral tube shell-and-tube heat exchanger and the shell-and-tube heat exchanger are located on the inner upper side and are arranged opposite each other and connected in parallel to the water outlet pipe. Both the water outlet pipe and the water inlet pipe are provided with temperature probe blind tubes and corresponding control valves.

[0010] Furthermore, a bypass pipe is connected to the bottom of the evaporator via the connecting pipe between the four-way valve and the shell-and-tube heat exchanger, and a one-way valve is provided on this connecting pipe. A return copper pipe is provided at the bottom of the evaporator, and the return copper pipe is bypassed to the connecting pipe between the shell-and-tube heat exchanger and the brazed plate heat exchanger. A temperature sensor, a pressure sensor, and a gas injector are sequentially provided on the connecting pipe between the second gas-liquid separator and the brazed plate heat exchanger in the direction of flow. A gas injector and a high-pressure switch are sequentially provided on the connecting pipe between the third compressor and the spiral tube shell-and-tube heat exchanger in the direction of flow. A dryer filter and a copper filter are connected in parallel on the connecting pipe between the second electronic expansion valve and the brazed plate heat exchanger.

[0011] Furthermore, a short-circuit pipe is connected to the inlet of the No. 1 gas-liquid separator via the pipe between the copper filter and the No. 1 electronic expansion valve. A solenoid valve is installed on the short-circuit pipe. A dryer filter and a copper filter are also connected in parallel on the connecting pipe between the No. 1 electronic expansion valve and the high-pressure liquid storage tank. A gas filler head, a temperature sensor, and a pressure sensor are sequentially installed on the connecting pipe between the No. 1 gas-liquid separator and the four-way valve in the direction of flow. A balance oil pipe connects the No. 1 compressor and the No. 2 compressor. A one-way valve is installed on the pipe behind the No. 1 compressor and the No. 2 compressor. A gas filler head and a high-pressure switch are sequentially installed on the combined pipe behind the No. 1 compressor and the No. 2 compressor in the direction of flow.

[0012] Furthermore, the distribution box is equipped with a control terminal for the heat pump unit, the exhaust fan wire is connected to a current transformer, and then the wire is connected to the control terminal. All the compressors and sensors mentioned above, as well as the high-voltage switch copper pipe, are connected to the control terminal for control. A wire groove is provided on the upper side of the longitudinal support rod.

[0013] The beneficial effects of this invention are as follows: 1. By using a bypass system design and multi-stage heat exchange, this invention ensures higher heating capacity in low-temperature areas while avoiding the problem of reduced heat pump heating capacity or even damage to the evaporator caused by external frost; 2. By using a short-circuit solenoid valve and multiple gas filling devices, this invention ensures stable system operation, while the solenoid valve opens when the pressure is insufficient, preventing damage to the evaporator due to insufficient system pressure during operation; 3. Through system structure optimization, solar heating, and a two-stage system, this invention effectively improves the system's utilization efficiency for low-quality heat, while further improving the unit's heating efficiency; 4. The heat pump system of this invention can guarantee the provision of hot water resources above 80°C in environments as low as -30°C, reducing the use of electricity or fuel and effectively saving energy; 5. This invention effectively avoids the frost problem caused by using the heat pump in low-temperature weather. The cooperation between the detection device and the defrosting and de-icing device effectively prevents damage to the heat pump and extends its service and maintenance time. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall system operation structure of the device of the present invention; Figure 2 This is a schematic diagram of the overall cone-shaped device structure of the present invention; Figure 3 This is a schematic diagram of the air duct structure of the present invention; Figure 4 This is a schematic diagram of the winding device structure of the present invention; Figure 5 This is a schematic diagram of the internal structure of the present invention; Figure 6 A schematic diagram of the evaporator installation structure; Figure 7 This is a schematic diagram of the lower part of the box body of the present invention.

[0015] In the diagram: 1-Box body, 2-Air duct, 3-Exhaust fan, 4-Ventilation window, 5-Grid mesh, 6-Electrical distribution box, 7-Inlet pipe, 8-Outlet pipe, 9-Base frame, 10-Longitudinal support rod, 11-Transverse support rod, 12-Gas-liquid separator No. 1, 13-Compressor No. 1, 14-Compressor No. 2, 15-Shell-tube heat exchanger, 16-Spiral tube shell-and-tube heat exchanger, 17-Compressor No. 3, 18-High-pressure liquid storage tank, 19-Gas-liquid separator No. 2, 20-Brazed plate heat exchanger, 21-Support frame, 22-Air duct, 23- Mounting frame, 24-Evaporator, 25-Rewinding motor, 26-Take-up reel, 27-Traction line, 28-Connecting rod, 29-Sealing cloth, 30-Roller, 31-Distribution copper pipe, 32-Manifold copper pipe, 33-Four-way valve, 34-Electronic expansion valve No. 1, 35-Evaporator distributor head, 36-Mounting plate, 37-Fan, 38-Inlet bend, 39-Guide plate, 40-Ear-shaped outlet, 41-Spiral pipe, 42-Return copper pipe, 43-Electronic expansion valve No. 2, 44-Solenoid valve, 45-Short-connection pipe, 46-Cable trough. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Combination Figures 1 to 7 Shown: A low-temperature air source heat pump unit includes a housing 1. Several air ducts 2 are symmetrically arranged on the top of the housing 1. Exhaust fans 3 are installed inside the air ducts 2. Heating wires are wrapped around the inside of the air ducts 2 to heat them, preventing ice buildup that could damage the fans during operation. The exhaust fan 3 is connected to a current transformer, which identifies changes in the fan's operating status via current changes and controls the fan to prevent damage to the fan blades. Ventilation windows 4 are provided around the top of the housing 1, each containing a mesh screen 5. Alternatively, louvers or filters can be used to effectively protect the internal components. A winding device is installed on the inner side of the housing above each ventilation window 4. The winding device includes components installed on the inner side of the housing at the top of the ventilation window 4. Several winding motors 25 are provided. A take-up wheel 26 is provided on the rotating shaft of the winding motor 25. A traction line 27 is provided on the take-up wheel 26. A connecting rod 28 is connected to the traction line 27. A groove is provided at the bottom of the connecting rod 28. A sealing cloth 29 is provided in the groove. It is held by the groove or glued. The sealing cloth 29 is made of PVC coated cloth or PU coated cloth. At the same time, the rotation of the winding motor drives the cloth to cover the ventilation window to prevent heat loss. It can prevent hot air heat from leaking out and improve the defrosting effect. The sealing cloth 29 is set on the roller 30. The two ends of the roller 30 are set in the box 1 inside the lower side of the fume hood 4. The two end boxes are also equipped with motors corresponding to the roller. The rotation of the motor shaft causes the roller to rotate, which facilitates the winding and unwinding of the sealing cloth.

[0018] The lower front end of the enclosure 1 is equipped with a distribution box 6, which contains the control terminal of the heat pump unit. The exhaust fan 3 is connected to a current transformer by wires, and then the wires are connected to the control terminal. All compressors and sensors, high-voltage switch copper pipes are connected to the control terminal for control, and other equipment and components that need to be controlled are also connected to the control terminal. The upper side of the longitudinal support rod 10 is equipped with a wire trough 46 for wiring.

[0019] The rear end of the housing 1 is equipped with an inlet pipe 7 and an outlet pipe 8 for hot water supply. A base frame 9 is located at the bottom of the housing 1. Two longitudinal support rods 10 are arranged on both sides of the base frame 9. Several transverse support rods 11 are arranged between the longitudinal support rods 10 and the sides of the base frame 9 at the bottom of the housing 1, forming two rows. On the left row of transverse support rods 11, from front to rear, are arranged a No. 1 gas-liquid separator 12, a No. 1 compressor 13, a No. 2 compressor 14, and a shell-and-tube heat exchanger 15. The right row of transverse support rods 11... The support rod 11 is equipped with a spiral tube shell-and-tube heat exchanger 16, a No. 3 compressor 17, a high-pressure liquid storage tank 18, a No. 2 gas-liquid separator 19, a brazed plate heat exchanger 20, and support frames 21 on the back of the distribution box 6 and the other end of the base frame 9 of the box body 1. The top center of the support frame 21 is equipped with an air duct 22. The top of the air duct 22 is an inverted V-shaped structure. The two sides of the inverted V-shaped structure of the air duct 22 are provided with mounting frames 23 to form an upward V-shaped structure. An evaporator 24 is provided inside the mounting frame 23.

[0020] The heat dissipation pipes within the evaporator 24 of the mounting frame 23 are configured as several parallel heat dissipation pipe structures. One side of each parallel heat dissipation pipe structure has a row of liquid distribution copper pipes 31 and a row of manifold copper pipes 32. The manifold copper pipes 32 are all connected in parallel and then merged to connect to a four-way valve 33. From there, they are connected to a first gas-liquid separator 12 via pipes through the four-way valve 33. The first gas-liquid separator 12 is connected to a first compressor 13 and a second compressor 14 via parallel pipes. These pipes are then merged and connected to the four-way valve 33. The four-way valve 33 is then connected to a shell-and-tube heat exchanger 15 via pipes. Finally, the shell-and-tube heat exchanger 15 is connected to a... The heat medium inlet of the plate heat exchanger 20 is brazed, and then the heat medium outlet pipe of the plate heat exchanger 20 is connected to the high-pressure liquid storage tank 18. The high-pressure liquid storage tank 18 is connected to the first electronic expansion valve 34. A copper filter is installed on the pipe behind the first electronic expansion valve 34. Then the pipe is divided into two parallel pipes, and the top of each parallel pipe is equipped with an evaporator distributor 35. The evaporator distributor 35 is connected to the distributor copper pipe 31 through the pipe to distribute the liquid and then it flows into the parallel heat dissipation pipe structure of the evaporator 24. After being connected in parallel through the manifold copper pipe 32, the liquid is merged and returned to the four-way valve 33 to form a circulation loop.

[0021] The transverse support rod 11 is a transversely open channel steel structure with several fixing holes on both sides of the channel steel. Several mounting plates 36 are provided between the transverse support rods 11 and are fixed to the transverse support rods 11 by screws and nuts in conjunction with the fixing holes. The mounting plates 36 are used to fix the No. 1 gas-liquid separator 12, the No. 1 compressor 13, the No. 2 compressor 14, the shell-and-tube heat exchanger 15, the spiral tube shell-and-tube heat exchanger 16, the No. 3 compressor 17, the high-pressure liquid storage tank 18, the No. 2 gas-liquid separator 19, and the brazed plate heat exchanger 20. The number and structure of the mounting plates can be further adjusted according to actual needs.

[0022] A fixing plate is located at the top right corner of the support frame 21 on one side of the distribution box 6. A fan 37 is mounted on the fixing plate. The bottom of the fan 37 has an air inlet bend 38 that connects to the outside of the box 1 for connecting to the solar hot air duct. This allows the solar device to provide hot air at a certain temperature in low temperatures, reducing the possibility of frost formation and increasing the heating effect. A guide plate 39 in the shape of an inverted right-angled trapezoid is connected to the side pipe of the fan 37. The opening of the guide plate 39 connects to one end of the air duct 22. Several round holes are evenly distributed at the bottom of the air duct 22. The sides of the air duct 22 have downward-opening ear-shaped air outlets 40. Hot air is discharged from the bottom of the V-shaped evaporator through the round holes and ear-shaped air outlets 40, ensuring the heat absorption effect.

[0023] The refrigerant outlet pipe of the brazed plate heat exchanger 20 is connected to the No. 2 gas-liquid separator 19. The No. 2 gas-liquid separator 19 is connected to the No. 3 compressor 17. The No. 3 compressor 17 is connected to the spiral tube shell-and-tube heat exchanger 16. The spiral tube shell-and-tube heat exchanger 16 is connected to the No. 2 electronic expansion valve 43 through a pipe and then connected to the refrigerant inlet of the brazed plate heat exchanger 20 to form a complete two-stage heating circuit. It can absorb heat from the compressed liquid of the previous stage at a higher temperature level, increase the heating temperature of the next stage, and improve the heating efficiency.

[0024] The spiral tube shell-and-tube heat exchanger 16 and the shell-and-tube heat exchanger are equipped with two coaxial and parallel spiral tubes 41 of different diameters, which can effectively enhance the heat transfer efficiency. The inlet of the spiral tube shell-and-tube heat exchanger 16 and the spiral tube 41 of the shell-and-tube heat exchanger are located on the bottom inner side and are connected to the inlet pipe 7 in parallel, which facilitates the supply of hot water. The outlet of the spiral tube shell-and-tube heat exchanger 16 and the spiral tube 41 of the shell-and-tube heat exchanger are located on the upper inner side and are connected to the outlet pipe 8 in parallel, which facilitates the control of the flow rate and the outlet water temperature. Both the outlet pipe 8 and the inlet pipe 7 are equipped with temperature probe blind tubes and corresponding control valves to facilitate the control of the flow rate and the outlet water temperature.

[0025] The bypass pipe on the connecting pipe between the four-way valve 33 and the shell-and-tube heat exchanger 15 is connected to the bottom of the evaporator 24. This prevents water from accumulating and freezing at the bottom after defrosting, thus preventing the ice at the bottom of the evaporator from being difficult to remove. A one-way valve is also provided on this connecting pipe. A return copper pipe 42 is provided at the bottom of the evaporator 24. The return copper pipe 42 is bypassed to the connecting pipe between the shell-and-tube heat exchanger 15 and the brazed plate heat exchanger 20. This allows for easy control of the bypass operation through the one-way valve. The connecting pipe between the second gas-liquid separator 19 and the brazed plate heat exchanger 20 is equipped with a temperature sensor, a pressure sensor, and a gas charging head in sequence according to the flow direction. Gas can be added to maintain the system pressure as needed. The connecting pipe between the third compressor 17 and the spiral tube shell-and-tube heat exchanger 16 is equipped with a gas charging head and a high-pressure switch in sequence according to the flow direction. A dryer filter and a copper filter are connected in parallel on the connecting pipe between the second electronic expansion valve 43 and the brazed plate heat exchanger 20 to ensure the purity of the refrigerant.

[0026] A short-connecting pipe 45 is connected to the inlet of the No. 1 gas-liquid separator 12 via the pipe between the No. 1 electronic expansion valve 34 and the copper filter on its rear side. A solenoid valve 44 is installed on the short-connecting pipe 45. A dryer filter and a copper filter are also installed in parallel on the connecting pipe between the No. 1 electronic expansion valve 34 and the high-pressure liquid storage tank 18. A gas charging head, a temperature sensor, and a pressure sensor are installed in sequence according to the flow direction on the connecting pipe between the No. 1 gas-liquid separator and the four-way valve 33. A balance oil pipe is connected between the No. 1 compressor and the No. 2 compressor. A one-way valve is installed on the pipe behind the No. 1 compressor 13 and the No. 2 compressor 14. A gas charging head and a high-pressure switch are installed in sequence according to the flow direction on the combined pipe behind the No. 1 compressor and the No. 2 compressor. When insufficient system pressure is detected, the solenoid valve 44 is opened, and the refrigerant does not flow into the evaporator 24 pipe but circulates directly to prevent the evaporator 24 from being damaged due to the pressure falling below the normal operating range of the system.

[0027] Working principle: Refrigerant flows out from the high-pressure storage tank, is filtered by a copper filter and a dryer filter, expands through an electronic expansion valve, absorbs heat after passing through the evaporator, transfers it to a four-way valve, flows through the No. 1 gas-liquid separator, is compressed by two parallel compressors, flows through a shell-and-tube heat exchanger and then through a brazed plate heat exchanger, returning to the high-pressure storage tank, forming a loop. The refrigerant outlet pipe of the brazed plate heat exchanger connects to the No. 2 gas-liquid separator, the pipe of the No. 2 gas-liquid separator connects to the No. 3 compressor, and the pipe of the No. 3 compressor connects to the spiral tube shell-and-tube heat exchanger. The spiral shell-and-tube heat exchanger is connected to the No. 2 electronic expansion valve via a pipeline, and then to the refrigerant inlet of the brazed plate heat exchanger to form a complete two-stage heating circuit. The bypass pipeline on the connection pipeline between the four-way valve and the shell-and-tube heat exchanger is connected to the return copper pipe at the bottom of the evaporator. The return copper pipe is connected to the connection pipeline between the shell-and-tube heat exchanger 15 and the brazed plate heat exchanger 20, which facilitates the control of the bypass operation through the action of the one-way valve. This bypass is used to heat the bottom of the evaporator, prevent moisture from accumulating and freezing, and ensure the efficiency and effect of defrosting.

[0028] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0029] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A low-temperature air source heat pump unit, characterized in that: The enclosure includes a housing (1), on which several air ducts (2) are symmetrically arranged on the top. An exhaust fan (3) is installed inside the air duct (2). An electric heating wire is arranged around the inside of the air duct (2). Ventilation windows (4) are provided around the upper part of the housing (1). A grid mesh (5) is provided inside the ventilation windows (4). A winding device is provided on the inner side of each ventilation window (4). A power distribution box (6) is provided at the lower front end of the housing (1). A water inlet pipe (7) and a water outlet pipe (8) are provided at the rear end of the housing (1). A base frame (9) is provided at the bottom inside the housing (1). Two longitudinal support rods (10) are arranged on both sides of the base frame (9). Several transverse support rods (11) are arranged between the longitudinal support rods (10) and the two sides of the base frame (9) at the bottom of the housing (1) to form two rows. The transverse support rods in the left row are arranged in two columns. (11) From front to back, there are a No. 1 gas-liquid separator (12), a No. 1 compressor (13), a No. 2 compressor (14) and a shell-and-tube heat exchanger (15). On the right side of the horizontal support rod (11), from back to front, there are a spiral tube shell-and-tube heat exchanger (16), a No. 3 compressor (17), a high-pressure liquid storage tank (18), a No. 2 gas-liquid separator (19), and a brazed plate heat exchanger (20). Support frames (21) are provided on the back of the distribution box (6) and the other end of the box body (1) base frame (9). A duct (22) is provided at the top center of the support frame (21). The top of the duct (22) is an inverted V-shaped structure. The two sides of the inverted V-shaped structure of the duct (22) are provided with mounting frames (23) to form an upward V-shaped structure. An evaporator (24) is provided in the mounting frame (23). The refrigerant in the evaporator (24) flows sequentially through the manifold copper pipe (32), the four-way valve (33), the first gas-liquid separator (12), the first compressor (13) and the second compressor (14) connected in parallel, and then through the four-way valve (33) through the shell-and-tube heat exchanger (15), the heat medium side of the brazed plate heat exchanger (20), the high-pressure liquid storage tank (18) and the first electronic expansion valve (34), and then flows back to the evaporator (24) through the liquid distribution copper pipe (31), forming a primary circulation loop; a dryer filter and a copper filter are connected in parallel on the connecting pipe between the high-pressure liquid storage tank (18) and the first electronic expansion valve (34), and a copper filter is provided on the pipe behind the first electronic expansion valve (34). A short-connecting pipe (45) is connected to the inlet of the first gas-liquid separator (12) on the pipe between the first electronic expansion valve (34) and the copper filter behind it, and a solenoid valve (44) is provided on the short-connecting pipe (45). The refrigerant side of the brazed plate heat exchanger (20) is connected to the refrigerant inlet of the brazed plate heat exchanger (20) via the No. 2 gas-liquid separator (19), the No. 3 compressor (17), the spiral tube shell heat exchanger (16), and the No. 2 electronic expansion valve (43) to form a two-stage heating circuit. The four-way valve (33) is connected to the shell-and-tube heat exchanger (15) via a bypass pipe, which is then connected to the bottom of the evaporator (24). A one-way valve is provided on this connecting pipe. A return copper pipe (42) is provided at the bottom of the evaporator (24), and the return copper pipe (42) is connected to the connecting pipe between the shell-and-tube heat exchanger (15) and the brazed plate heat exchanger (20).

2. The low-temperature air source heat pump unit according to claim 1, characterized in that: The winding device includes several winding motors (25) installed at the top of the ventilation window (4). The winding motor (25) has a winding wheel (26) on its rotating shaft. The winding wheel (26) has a traction line (27) on it. The traction line (27) is connected to a connecting rod (28). The bottom of the connecting rod (28) has a groove. The groove contains a sealing cloth (29). The sealing cloth (29) is made of PVC coated cloth or PU coated cloth. The sealing cloth (29) is installed on the roller (30). Both ends of the roller (30) are located inside the housing (1).

3. A low-temperature air source heat pump unit according to claim 1, characterized in that: The heat dissipation pipes in the evaporator (24) within the mounting frame (23) are configured as a plurality of parallel heat dissipation pipe structures, and a row of liquid distribution copper pipes (31) and a row of manifold copper pipes (32) are provided on one side of the parallel heat dissipation pipe structure.

4. A low-temperature air source heat pump unit according to claim 1, characterized in that: The transverse support rod (11) is a transversely open channel steel structure with several fixing holes on both sides of the channel steel. Several mounting plates (36) are provided between the transverse support rods (11) and are fixed to the transverse support rods (11) by screws and nuts in conjunction with the fixing holes. The mounting plates (36) are used to fix the No. 1 gas-liquid separator (12), the No. 1 compressor (13), the No. 2 compressor (14), the shell-and-tube heat exchanger (15), the spiral tube shell-and-tube heat exchanger (16), the No. 3 compressor (17), the high-pressure liquid storage tank (18), the No. 2 gas-liquid separator (19), and the brazed plate heat exchanger (20).

5. A low-temperature air source heat pump unit according to claim 1, characterized in that: A fixing plate is provided at the top right corner of the support frame (21) on one side of the distribution box (6). A fan (37) is provided on the fixing plate. An air inlet bend (38) is provided at the bottom of the fan (37) to connect to the outside of the box body (1) for connecting to the solar hot air pipe. A guide plate (39) in the shape of an inverted right trapezoid is connected to the pipe on the side of the fan (37). The opening of the guide plate (39) is connected to one end of the air duct (22). Several round holes are evenly provided at the bottom of the air duct (22). The two sides of the air duct (22) are provided with ear-shaped air outlets (40) with downward openings.

6. A low-temperature air source heat pump unit according to claim 1, characterized in that: The spiral tube shell-and-tube heat exchanger (16) and the shell-and-tube heat exchanger (15) are provided with two spiral tubes (41) of different diameters, coaxial and in the same direction, arranged in parallel. The inlet of the spiral tube (41) of the spiral tube shell-and-tube heat exchanger (16) and the shell-and-tube heat exchanger (15) is located on the bottom inner side and is arranged opposite to each other and connected in parallel to the inlet pipe (7). The outlet of the spiral tube (41) of the spiral tube shell-and-tube heat exchanger (16) and the shell-and-tube heat exchanger (15) is located on the upper inner side and is arranged opposite to each other and connected in parallel to the outlet pipe (8). The outlet pipe (8) and the inlet pipe (7) are both provided with temperature probe blind tubes and corresponding control valves.

7. A low-temperature air source heat pump unit according to claim 1, characterized in that: The connecting pipe between the No. 2 gas-liquid separator (19) and the brazed plate heat exchanger (20) is provided with a temperature sensor, a pressure sensor and a gas filling head in sequence according to the flow direction. The connecting pipe between the No. 3 compressor (17) and the spiral tube shell heat exchanger (16) is provided with a gas filling head and a high-pressure switch in sequence according to the flow direction.

8. A low-temperature air source heat pump unit according to claim 1, characterized in that: The gas-liquid separator No. 1 and the four-way valve (33) are connected by a gas filler head, a temperature sensor and a pressure sensor in sequence according to the flow direction. The compressor No. 1 (13) and the compressor No. 2 (14) are connected by a balance oil pipe. The pipes behind the compressor No. 1 (13) and the compressor No. 2 (14) are equipped with check valves. The combined pipes behind the compressor No. 1 (13) and the compressor No. 2 (14) are connected by a gas filler head and a high-pressure switch in sequence according to the flow direction.

9. A low-temperature air source heat pump unit according to claim 1, characterized in that: The distribution box (6) is equipped with a control terminal for the heat pump unit. The exhaust fan (3) is connected to a current transformer by a wire, and then the wire is connected to the control terminal. All compressors, sensors, and high-voltage switch copper pipes are connected to the control terminal for control. The longitudinal support rod (10) is equipped with a wire groove (46) on its upper side.

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