A self-cascade heat pump system and air conditioner

Abstract

The utility model provides a kind of self-recovery heat pump system and air conditioner, wherein, self-recovery heat pump system includes compressor, indoor heat exchanger, outdoor heat exchanger, condensing evaporator, first gas-liquid separator and second gas-liquid separator;Compressor has suction port, exhaust port and air supplement port;First gas-liquid separator has first A overflow port, second A overflow port and first air outlet;Second gas-liquid separator has first B overflow port, second B overflow port and second air outlet;Condensing evaporator has the first heat exchange channel and the second heat exchange channel of mutual heat exchange;First heat exchange channel and second air outlet are communicated, and both are communicated with air supplement port by first flow channel;Second heat exchange channel and first air outlet are communicated, and both are communicated with air supplement port by second flow channel;First flow channel and second flow channel both can be opened or closed.According to the technical scheme of the utility model, the output of self-recovery heat pump system heating and refrigeration capacity can be improved.

Description

Technical Field

[0001] This utility model belongs to the field of air conditioning technology, specifically relating to a self-cascading heat pump system and an air conditioner. Background Technology

[0002] Traditional heating methods, such as coal-fired heating, raise concerns due to their high pollution levels, low efficiency, and non-renewable nature. While air-source heat pump technology has made significant progress in replacing traditional heating methods, heat pump equipment is still predominantly low-temperature heat pumps, typically outputting temperatures below 55°C. When retrofitting coal-fired heating systems with heat pump technology, higher-temperature hot water must be output to match the indoor terminal equipment in the original system. However, applying the currently widely used vapor compression air-source heat pumps to cold regions presents several drawbacks: reduced heating capacity, decreased heating efficiency, increased compressor exhaust temperature leading to heat pump malfunction or reduced reliability, and low outlet air temperature severely impacting indoor comfort. Therefore, to apply heat pump technology to cold regions, the impact of low-temperature environments on its performance must be overcome.

[0003] Because compressors are limited by evaporation and condensation pressures, it is difficult to achieve low temperatures at room temperature using only one refrigerant. Therefore, cascade systems or multi-stage compression cycles are often used. Cascade systems combine high-temperature and low-temperature refrigerant cycles through an evaporator-condenser system to achieve the function of creating a low-temperature environment. However, cascade systems have complex structures and high equipment costs, while self-cascade systems typically have the advantages of simple structure and easy control.

[0004] Cascade technology can achieve a larger operating temperature difference using a single compressor and is now widely used in various low-temperature equipment such as cryogenic storage boxes, cryogenic constant temperature baths, vacuum freeze dryers, and natural gas liquefaction plants, as well as various high-temperature equipment such as heat pump water heaters and heating heat pumps. This technology is an effective way to achieve large temperature difference heating in high-temperature heat pumps. However, under the condition of outdoor heat exchanger frosting, the low-temperature heat exchange performance is severely reduced, which leads to a deterioration in heating performance and operating conditions, which is not conducive to the long-term use of heat pumps, and the reliability and comfort are relatively poor. Therefore, cascade heating systems usually require an additional electric defrosting device, which not only consumes a lot of defrosting energy but also has poor operating effect. At the same time, cascade heating units can only achieve heating and cannot be used for cooling output in hot seasons.

[0005] Common residential refrigeration units provide heating in cold seasons and operate in cooling mode in hot summers. However, in harsh winters, they often experience frost buildup, affecting operation and even preventing normal startup in some frigid regions. Due to compressor limitations, the extreme ambient temperature for single-stage compression refrigeration systems is typically above -25°C, and the COP under these conditions is only around 1.5. Residential units with both cooling and heating modes can automatically defrost when outdoor unit frosts under low-temperature heating conditions by switching to cooling mode. When using cascade refrigeration technology to extend the lower limit of winter operating temperature for residential units, the refrigerant separation and circulation issues caused by mode switching need to be considered.

[0006] like Figure 1 As shown, existing related patents disclose a self-cascading heat pump system, which includes a refrigerant circulation loop connected by a jet enthalpy-increasing compressor 1', a four-way valve 2', an indoor heat exchanger 3', an outdoor heat exchanger 4', a first gas-liquid separator 5', a first expansion valve 6', an evaporator-condenser 7', a first one-way valve 8', a second gas-liquid separator 9', a second expansion valve 10', a second one-way valve 11', a first auxiliary throttling device 13', a second auxiliary throttling device 14', a jet enthalpy valve 15', a first three-way valve 16', a second three-way valve 17', a third expansion valve 18', and a fourth expansion valve 19'. This self-cascade heat pump system has heating and cooling modes. In heating mode, the enthalpy injection valve 15' is opened. The high-temperature refrigerant absorbs heat and vaporizes in the evaporator-condenser 7', then passes through the first auxiliary throttling device 13' and the first one-way valve 8' before entering the compressor's enthalpy injection port through the enthalpy injection valve 15'. Meanwhile, the low-temperature refrigerant flows out of the gas pipe of the second gas-liquid separator 9', and part of the refrigerant gas sequentially passes through the second auxiliary throttling device 14', the second one-way valve 11', and the enthalpy injection valve 15' before entering the compressor's enthalpy injection port. This reduces the refrigerant flow rate of the outdoor heat exchanger 4' (which acts as an evaporator at this time), thus reducing the amount of heat absorbed by the system from the outside (reducing the cooling capacity) and indirectly reducing the system's heating capacity output. Similarly, in cooling mode, some low-temperature refrigerant gas will sequentially pass through the first auxiliary throttling device 13', the first one-way valve 8', and the enthalpy injection valve 15' into the compressor's enthalpy injection port, which will also reduce the refrigerant flow rate of the indoor heat exchanger 3' (which acts as a low-pressure evaporator at this time) and reduce the system's cooling capacity output. Utility Model Content

[0007] Therefore, this utility model provides a self-cascading heat pump system and an air conditioner, and the main technical problem to be solved is: how to improve the output of the heating and cooling capacity of the self-cascading heat pump system.

[0008] To address the aforementioned problems, this utility model provides a self-cascading heat pump system, comprising a compressor, an indoor heat exchanger, an outdoor heat exchanger, a condenser-evaporator, a first gas-liquid separator, and a second gas-liquid separator; the compressor has an intake port, an exhaust port, and a make-up air port; the exhaust port is selectively connected to one end of the indoor heat exchanger and one end of the outdoor heat exchanger, and the other end of the indoor heat exchanger and one end of the outdoor heat exchanger is connected to the intake port;

[0009] The first gas-liquid separator has a first A-flow port, a second A-flow port, and a first outlet; the second gas-liquid separator has a first B-flow port, a second B-flow port, and a second outlet; the condenser-evaporator has a first heat exchange channel and a second heat exchange channel that can exchange heat with each other; the other end of the indoor heat exchanger is connected to the first A-flow port through a first throttling device, and the second A-flow port is connected to one end of the first heat exchange channel through a second throttling device; the other end of the first heat exchange channel and the second outlet are both connected, and both are connected to the make-up air port through a first flow channel; one end of the second heat exchange channel is connected to the first outlet, and both are connected to the make-up air port through a second flow channel; the other end of the second heat exchange channel is connected to the second B-flow port through a third throttling device, and the first B-flow port is connected to the other end of the outdoor heat exchanger through a fourth throttling device; wherein, both the first flow channel and the second flow channel can be opened or closed.

[0010] In some embodiments, the self-cascade heat pump system has a heating mode and a cooling mode;

[0011] In the heating mode, the exhaust port is connected to one end of the indoor heat exchanger, and the first flow channel is open while the second flow channel is closed; in the cooling mode, the exhaust port is connected to one end of the outdoor heat exchanger, and the first flow channel is closed while the second flow channel is open.

[0012] In some embodiments, the first flow channel, the second flow channel, and the air inlet are connected by a three-way valve;

[0013] Both the first flow channel and the second flow channel are opened or closed via the three-way valve.

[0014] In some embodiments, the self-cascade heat pump system further includes a controller and a four-way valve; the air intake, the air exhaust, one end of the indoor heat exchanger, and one end of the outdoor heat exchanger are connected one-to-one to the four ports of the four-way valve, so that the air exhaust can be selectively connected to one of the two ends of the indoor heat exchanger and the outdoor heat exchanger through the four-way valve, and the other end of the two ends is connected to the air intake through the four-way valve;

[0015] Both the four-way valve and the three-way valve are communicatively connected to the same signal port of the controller.

[0016] In some embodiments, the four-way valve has a C port, an S port, an E port, and a D port. The four-way valve is connected to one end of the outdoor heat exchanger through the C port, to the air intake port through the S port, to one end of the indoor heat exchanger through the E port, and to the exhaust port through the D port. The three-way valve has an O port, an M port, and an N port. The three-way valve is connected to the air supply port through the O port, to the second flow channel through the M port, and to the first flow channel through the N port.

[0017] In the first state, both the three-way valve and the four-way valve control the O port to be connected only to the M port (between the M and N ports), and the four-way valve controls the D port to be connected to the C port and the S port to be connected to the E port. In the second state, both the three-way valve and the four-way valve control the O port to be connected only to the N port (between the M and N ports), and the four-way valve controls the D port to be connected to the E port and the S port to be connected to the C port. One of the first state and the second state is a power-off state, and the other is a power-on state. The controller switches both the three-way valve and the four-way valve to the first state or the second state via the signal port.

[0018] In some embodiments, the first throttling device has a first A end and a second A end, the first throttling device being connected to the other end of the indoor heat exchanger through the first A end, and connected to the first A outlet through the second A end;

[0019] The first throttling device has a first check valve connected in parallel at both ends. The first check valve has an inlet A and an outlet A. The first check valve is connected to the first A end through the inlet A and to the second A end through the outlet A.

[0020] In some embodiments, the fourth throttling device has a first B end and a second B end, the fourth throttling device being connected to the other end of the outdoor heat exchanger through the first B end, and connected to the first B outlet through the second B end;

[0021] The fourth throttling device has a second check valve connected in parallel at both ends. The second check valve has an inlet (B) and an outlet (B). The second check valve is connected to the first end (B) through the inlet (B) and to the second end (B) through the outlet (B).

[0022] In some embodiments, the first throttling device, the second throttling device, the third throttling device, and the fourth throttling device are all throttle valves;

[0023] When the self-cascade heat pump system is shut down, the opening degree of the first throttling device, the second throttling device, the third throttling device and the fourth throttling device are all at their maximum opening degree.

[0024] In some embodiments, the refrigerant circulating in the self-cascade heat pump system is a non-azeotropic refrigerant, which is a refrigerant composed of two or more refrigerants with different boiling points.

[0025] This utility model also provides an air conditioner that includes the self-cascading heat pump system described in any one of the above descriptions.

[0026] The self-cascading heat pump system and air conditioner provided by this utility model have the following beneficial effects:

[0027] 1. In heating mode, this invention can improve the system's heating capacity output by opening the first flow channel and closing the second flow channel. In cooling mode, it can improve the system's cooling capacity output by closing the first flow channel and opening the second flow channel.

[0028] 2. This utility model adopts a gas-injecting enthalpy-increasing compressor, using the medium-pressure enthalpy-increasing gas injection port as the suction port for high-temperature refrigerant gas; at the same time, a three-way valve switches the connection between the gas injection port and the first and second flow channels in different modes, ensuring that the medium-pressure enthalpy-increasing gas injection port mainly returns high-temperature refrigerant gas, and the compressor's low-pressure suction port mainly returns low-temperature refrigerant gas, thereby achieving low-pressure separation of the two refrigerants. This improves the operational reliability of the heat pump unit using cascade refrigeration technology, simplifies the system's control valves and system components, ensures the low-pressure separation effect of the two refrigerants in different modes, and guarantees the system's capacity output.

[0029] 3. The three-way valve and four-way valve of this utility model realize the same port signal control. The two control valves only need to use one control port signal, which can simplify the hardware and software design of the controller, reduce costs, and improve the reliability of the system.

[0030] 4. When the self-cascade heat pump system of this utility model is shut down, all throttling devices, such as the expansion valve, are adjusted to the maximum opening to ensure that the refrigerant liquid is interconnected between the indoor heat exchanger, the outdoor heat exchanger, the first gas-liquid separator, and the second gas-liquid separator, serving as a liquid storage backup space for each other. This prevents the refrigerant liquid from being squeezed into the compressor suction port, thereby ensuring the reliability of the compressor's restart operation. Attached Figure Description

[0031] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0032] Figure 1 This is a structural schematic diagram of a prior art self-cascade heat pump system;

[0033] Figure 2 This is a schematic diagram of the structure of the self-cascading heat pump system of this utility model.

[0034] The attached figures are labeled as follows:

[0035] 1. Compressor; 1a. Discharge port; 1b. Inlet port; 1c. Make-up port; 2. Indoor heat exchanger; 3. Outdoor heat exchanger; 4. Four-way valve; 5. First throttling device; 6. First check valve; 7. First gas-liquid separator; 8. Second throttling device; 9. Condenser-evaporator; 10. Third throttling device; 11. First flow channel; 12. Second flow channel; 13. Three-way valve; 14. Second gas-liquid separator; 15. Fourth throttling device; 16. Second check valve; 21. One end of the indoor heat exchanger; 22. The other end of the indoor heat exchanger; 31. Outdoor heat exchanger 32. The other end of the outdoor heat exchanger; 51. First A end; 52. Second A end; 71. First A flow port; 72. Second A flow port; 73. First air outlet; 91. First heat exchange channel; 92. Second heat exchange channel; 141. First B flow port; 142. Second B flow port; 143. Second air outlet; 151. First B end; 152. Second B end; 911. One end of the first heat exchange channel; 912. The other end of the first heat exchange channel; 921. One end of the second heat exchange channel; 922. The other end of the second heat exchange channel. Detailed Implementation

[0036] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0037] In the description of this utility model, it should be understood that the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0038] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0039] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this utility model.

[0040] See also Figure 2 As shown, according to an embodiment of the present invention, a self-cascading heat pump system is provided, which includes a compressor 1, an indoor heat exchanger 2, an outdoor heat exchanger 3, a condenser-evaporator 9, a first gas-liquid separator 7, and a second gas-liquid separator 14.

[0041] The compressor 1 described above can be a gas-injection enthalpy-increasing compressor, which has an intake port 1b, an exhaust port 1a, and a gas-injection port 1c. The exhaust port 1a can be selectively connected to one end 21 of the indoor heat exchanger or one end 31 of the outdoor heat exchanger, and the other end 21 of the indoor heat exchanger or one end 31 of the outdoor heat exchanger is connected to the intake port 1b. Thus, by switching the exhaust port 1a to connect to either end 21 of the indoor heat exchanger or end 31 of the outdoor heat exchanger, the self-cascading heat pump system of this invention can be placed in heating mode or cooling mode. The connection between the exhaust port 1a and the intake port 1b and the end 21 of the indoor heat exchanger or the end 31 of the outdoor heat exchanger can be achieved through a four-way valve 4. Specifically, the air intake 1b, the exhaust 1a, one end 21 of the indoor heat exchanger, and one end 31 of the outdoor heat exchanger are connected to the four ports of the four-way valve 4 in a one-to-one correspondence, so that the exhaust 1a can be selectively connected to one of the two ends 21 of the indoor heat exchanger and one end 31 of the outdoor heat exchanger through the four-way valve 4, and the other of the two ends 21 of the indoor heat exchanger and one end 31 of the outdoor heat exchanger is connected to the air intake 1b through the four-way valve 4.

[0042] The aforementioned first gas-liquid separator 7 has a first A-flow port 71, a second A-flow port 72, and a first outlet 73. The second gas-liquid separator 14 has a first B-flow port 141, a second B-flow port 142, and a second outlet 143. The condenser-evaporator 9 has a first heat exchange channel 91 and a second heat exchange channel 92 that can exchange heat with each other. The other end 22 of the aforementioned indoor heat exchanger is connected to the first A-flow port 71 through a first throttling device 5, and the second A-flow port 72 is connected to one end 911 of the first heat exchange channel through a second throttling device 8. The other end 912 of the first heat exchange channel and the second outlet 143 are connected, and both the other end 912 of the first heat exchange channel and the second outlet 143 are connected to the air supply port 1c of the compressor 1 through a first flow channel 11. One end 921 of the second heat exchange channel is connected to the first air outlet 73, and both the second end 921 and the first air outlet 73 are connected to the air supply port 1c of the compressor 1 through the second flow channel 12. The other end 922 of the second heat exchange channel is connected to the second B flow port 142 through the third throttling device 10. The first B flow port 141 is connected to the other end 32 of the outdoor heat exchanger through the fourth throttling device 15. Both the first flow channel 11 and the second flow channel 12 can be opened or closed.

[0043] The refrigerant circulating in the aforementioned self-cascade heat pump system is generally a non-azeotropic refrigerant, which is a mixture of two or more refrigerants with different boiling points. Non-azeotropic refrigerants include high-temperature refrigerants and low-temperature refrigerants.

[0044] In the above example, the self-cascade heat pump system of this invention can be switched between heating mode and cooling mode by switching the connection between the exhaust port 1a and the intake port 1b and one end of the indoor heat exchanger 2 and the outdoor heat exchanger 3. Specifically, when the exhaust port 1a is connected to one end 21 of the indoor heat exchanger and the intake port 1b is connected to one end 31 of the outdoor heat exchanger, the self-cascade heat pump system can be in heating mode. In this heating mode, the first flow channel 11 can be opened and the second flow channel 12 can be closed, so that the low-temperature refrigerant separated from the first gas-liquid separator 7 flows into the second gas-liquid separator 14 and the outdoor heat exchanger 3 through the second heat exchange channel 92 and enters the intake port 1b of the compressor 1. Compared with the prior art where some low-temperature refrigerant does not pass through the outdoor heat exchanger 3 in heating mode, the low-temperature refrigerant of this invention flows entirely through the outdoor heat exchanger 3, thereby increasing the flow rate of refrigerant in the outdoor heat exchanger 3, increasing the heat absorbed by the system from the outside, and thus improving the heating capacity output of the system. When the exhaust port 1a is connected to one end 31 of the outdoor heat exchanger and the suction port 1b is connected to one end 21 of the indoor heat exchanger, the self-cascade heat pump system can be in cooling mode. In this cooling mode, the first flow channel 11 can be closed and the second flow channel 12 can be opened, so that the low-temperature refrigerant separated from the second gas-liquid separator 14 flows into the first gas-liquid separator 7 and the indoor heat exchanger 2 through the first heat exchange channel 91 and enters the suction port 1b of the compressor 1. Compared with the prior art, in the cooling mode, some low-temperature refrigerant does not pass through the indoor heat exchanger 2. In this invention, the low-temperature refrigerant flows through the indoor heat exchanger 2, thereby increasing the flow rate of the refrigerant in the indoor heat exchanger 2, increasing the heat absorbed by the system from the room, and thus improving the cooling capacity output of the system.

[0045] As described above, by switching the connection between the intake port 1b and the exhaust port 1a and one end of the indoor heat exchanger 2 and the outdoor heat exchanger 3, the self-cascading heat pump system of this invention can have both a heating mode and a cooling mode. In heating mode, the exhaust port 1a is connected to one end 21 of the indoor heat exchanger, and correspondingly, the intake port 1b is connected to one end 31 of the outdoor heat exchanger. In this heating mode, the first flow channel 11 is open and the second flow channel 12 is closed, thus increasing the system's heating capacity output. In cooling mode, the exhaust port 1a is connected to one end 31 of the outdoor heat exchanger, and correspondingly, the intake port 1b is connected to one end 21 of the indoor heat exchanger. In this cooling mode, the first flow channel 11 is closed and the second flow channel 12 is open, thus increasing the system's cooling capacity output.

[0046] It should be noted that the structures of the first gas-liquid separator 7 and the second gas-liquid separator 14 described above are both existing technologies. The first gas-liquid separator 7 has a first gas-liquid separation chamber, with the first A-flow port 71 and the second A-flow port 72 both extending into the bottom of the first gas-liquid separation chamber, and the first air outlet 73 extending into the upper part of the first gas-liquid separation chamber. The second gas-liquid separator 14 has a second gas-liquid separation chamber, with the first B-flow port 141 and the second B-flow port 142 both extending into the bottom of the second gas-liquid separation chamber, and the second air outlet 143 extending into the upper part of the second gas-liquid separation chamber.

[0047] In a specific application example, one end 31 of the aforementioned outdoor heat exchanger is a gas pipe port, and the other end 32 of the outdoor heat exchanger is a liquid pipe port. One end 21 of the aforementioned indoor heat exchanger is a gas pipe port, and the other end 22 of the indoor heat exchanger is a liquid pipe port.

[0048] To achieve the aforementioned function that both the first flow channel 11 and the second flow channel 12 can be opened or closed, in some embodiments, such as Figure 2 As shown, the aforementioned first flow channel 11, second flow channel 12, and air inlet 1c can be connected by a three-way valve 13. Both the first flow channel 11 and the second flow channel 12 can be opened or closed via the three-way valve 13.

[0049] In the example above, the opening and closing of both the first flow channel 11 and the second flow channel 12 can be controlled simultaneously by a single three-way valve 13, which has the advantage of saving the number of valves.

[0050] In some embodiments, the aforementioned self-cascade heat pump system also includes a controller. Both the four-way valve 4 and the three-way valve 13 can be communicatively connected to the same signal port of the controller, such as through an electrical connection. This allows both the four-way valve 4 and the three-way valve 13 to be controlled using a single control port signal, thus simplifying the hardware and software design of the controller, reducing costs, and improving system reliability.

[0051] In a specific application example, such as Figure 2 As shown, the aforementioned four-way valve 4 has a C port, an S port, an E port, and a D port. The four-way valve 4 is connected to one end 31 of the outdoor heat exchanger via the C port, and is connected to the intake port 1b via the S port, one end 21 of the indoor heat exchanger via the E port, and the exhaust port 1a via the D port. The S port of the four-way valve 4 is the low-pressure gas outlet, and the D port is the high-pressure gas inlet. The aforementioned three-way valve 13 has an O port, an M port, and a N port. The three-way valve 13 is connected to the make-up air port 1c via the O port, the second flow channel 12 via the M port, and the first flow channel 11 via the N port.

[0052] In the first state, the three-way valve 13 controls the O port to be connected only to the M port (M or N), while the four-way valve 4 controls the D port to be connected to the C port and the S port to be connected to the E port. In this state, the self-cascading heat pump system is in cooling mode, and the first flow channel 11 is closed while the second flow channel 12 is open. In the second state, the three-way valve 13 controls the O port to be connected only to the N port (M or N), while the four-way valve 4 controls the D port to be connected to the E port and the S port to be connected to the C port. In this state, the self-cascading heat pump system is in heating mode, and the first flow channel 11 is open while the second flow channel 12 is closed. One of the first and second states is a power-off state, and the other is a power-on state. The controller can switch the three-way valve 13 and the four-way valve 4 to either the first or second state via the same signal port.

[0053] In the above example, the solenoid coils of the three-way valve 13 and the four-way valve 4 share a common control signal port to achieve synchronization of their opening and closing states, thereby ensuring that the low-pressure gas of the high-temperature refrigerant enters the medium-pressure enthalpy booster port 1c of the compressor 1 through the three-way valve 13. Figure 2 The diagram shows "DC on / ES on" and "MO on / NO off," which typically corresponds to the solenoid coils of three-way valve 13 and four-way valve 4 being in a default off-state, corresponding to the cooling mode. When the solenoid coils of three-way valve 13 and four-way valve 4 are energized, the configuration is "DE on / CS on" and "MO off / NO on," corresponding to the heating mode. The controller can switch both three-way valve 13 and four-way valve 4 to the first state (off-state) or the second state (on-state) via the same signal port. This simplifies the hardware and software design of the controller, reduces costs, and improves system reliability.

[0054] It should be noted that the aforementioned four-way valve 4 is controlled by an electromagnetic coil. In its default power-off state, it is used in the main heat pump system operating mode to save control energy and extend the lifespan of the electromagnetic four-way valve 4. For example, if the heat pump system is mainly used for cooling, then the opening and closing state of the four-way valve 4 in the default power-off state corresponds to the cooling mode. If the heat pump system mainly operates in heating mode and is rarely used for cooling (for example, in northern regions where it is used for winter heating and less for summer cooling), then the opening and closing state of the four-way valve 4 when powered off can adopt the connection relationship corresponding to the heating mode.

[0055] In a specific application example, the three-way valve 13 and the four-way valve 4 mentioned above can be assumed to be in a power-off state, corresponding to the cooling mode.

[0056] In some of the above methods, such as Figure 2As shown, the aforementioned first throttling device 5 has a first A end 51 and a second A end 52. The first throttling device 5 is connected to the other end 22 of the aforementioned indoor heat exchanger through the first A end 51, and the first throttling device 5 is connected to the aforementioned first A outlet 71 through the second A end 52. A first one-way valve 6 is connected in parallel to both ends of the first throttling device 5. The first one-way valve 6 has an A inlet and an A outlet. The first one-way valve 6 is connected to the first A end 51 through the A inlet, and is connected to the second A end 52 through the A outlet.

[0057] In the above example, by connecting a first one-way valve 6 in parallel across the first throttling device 5, the first one-way valve 6 corresponds to the main flow channel in heating mode. In heating mode, the first throttling device 5 is only an auxiliary flow channel and can even be closed. At this time, the refrigerant from the indoor heat exchanger 2 to the first gas-liquid separator 7 cannot be throttled and depressurized, and the flow resistance needs to be minimized. The function of the first one-way valve 6 is to reduce the flow resistance of the refrigerant in heating mode. Without the first one-way valve 6, the refrigerant must pass through the first throttling device 5 regardless of the mode, resulting in very high flow resistance, which would reduce the system's energy efficiency ratio, and might even cause the low-temperature refrigerant to be throttled and depressurized to form a liquid state. In this case, the low-temperature gas and high-temperature liquid cannot be formed in the first gas-liquid separator 7, thus losing the gas-liquid separation function, and the self-cascade system may fail.

[0058] In some implementations, such as Figure 2 As shown, the aforementioned fourth throttling device 15 has a first B end 151 and a second B end 152. The fourth throttling device 15 is connected to the other end 32 of the aforementioned outdoor heat exchanger through the first B end 151, and the fourth throttling device 15 is connected to the aforementioned first B outlet 141 through the second B end 152. A second one-way valve 16 is connected in parallel to both ends of the fourth throttling device 15. The second one-way valve 16 has a B inlet and a B outlet. The second one-way valve 16 is connected to the first B end 151 through the B inlet, and is connected to the second B end 152 through the B outlet.

[0059] In the above example, by connecting a second one-way valve 16 in parallel across the two ends of the fourth throttling device 15, the second one-way valve 16 corresponds to the main flow channel in the cooling mode. In the cooling mode, the fourth throttling device 15 is only an auxiliary flow channel and can even be closed. At this time, the refrigerant from the outdoor heat exchanger 3 to the second gas-liquid separator 14 cannot be throttled and its pressure reduced, and the flow resistance needs to be minimized. The function of the second one-way valve 16 is to reduce the flow resistance of the refrigerant in the cooling mode. Without the second one-way valve 16, the refrigerant must pass through the fourth throttling device 15 regardless of the mode, resulting in very high flow resistance, which would reduce the system's energy efficiency ratio, and might even cause the low-temperature refrigerant to throttle and depressurize, forming a liquid state. In this case, the low-temperature gas and high-temperature liquid cannot be formed in the second gas-liquid separator 14, thus losing the gas-liquid separation function, and the self-cascade system may fail.

[0060] In some implementations, such as Figure 2 As shown, the aforementioned first throttling device 5, second throttling device 8, third throttling device 10, and fourth throttling device 15 can all be throttling valves, such as electronic expansion valves. When the self-cascade heat pump system is shut down, the opening degree of each of the first throttling device 5, second throttling device 8, third throttling device 10, and fourth throttling device 15 is at its maximum.

[0061] In the above example, when the system shuts down, the low-temperature refrigerant liquid is heated and pressurized in the indoor heat exchanger 2 and outdoor heat exchanger 3 due to the temperature rise of the outside air. It then returns to the first gas-liquid separator 7 or the second gas-liquid separator 14 through the first one-way valve 6 or the second one-way valve 16. After the low-temperature refrigerant gas enters each gas-liquid separator, it will compress the liquid space in the gas-liquid separator. This may cause the high-temperature refrigerant liquid to enter the condenser evaporator 9 after passing through the second throttling device 8 and the third throttling device 10, and even enter the medium-pressure enthalpy injection port 1c of the compressor 1. This may easily cause liquid slugging when the compressor 1 restarts. Therefore, this phenomenon must be prevented. In the technical solution of this utility model, after the system stops, by adjusting the opening of the first throttling device 5, the second throttling device 8, the third throttling device 10 and the fourth throttling device 15 to the maximum, the refrigerant liquid squeezed by the refrigerant gas can flow between the indoor heat exchanger 2, the outdoor heat exchanger 3, the condenser evaporator 9, the first gas-liquid separator 7 and the second gas-liquid separator 14, so as to prevent the liquid from being squeezed into the medium-pressure enthalpy injection port 1c and / or the low-pressure suction port 1b of the compressor 1, thereby preventing liquid slugging during the restart of the compressor 1.

[0062] It should be noted that: the indoor heat exchanger 2 and the outdoor heat exchanger 3 mentioned above can both be finned tube heat exchangers. These heat exchangers mainly use a fan to drive air to exchange heat with the refrigerant inside the heat exchanger. When the air temperature changes significantly, the finned heat exchange effect will also cause changes in the temperature and pressure of the refrigerant inside the heat exchanger. Usually, the condenser evaporator 9 does not directly face the outdoor air and does not exchange heat with the outside air (ignoring natural heat dissipation).

[0063] The refrigerant circulation in the self-cascade heat pump system of this invention is shown below:

[0064] like Figure 2 As shown, the cooling mode is as follows: Compressor 1 → Four-way valve D port → Four-way valve C port → Outdoor heat exchanger 3 → Second one-way valve 16 and / or fourth throttling device 15 → Second gas-liquid separator 14 → (High-temperature refrigerant: Third throttling device 10 → Second heat exchange channel 92 of condenser-evaporator 9 → Three-way valve M port → Three-way valve O port → Compressor 1 medium-pressure enthalpy boosting gas injection port 1c; Low-temperature refrigerant: First heat exchange channel 91 of condenser-evaporator 9 → Second throttling device 8 → First gas-liquid separator 7 → First throttling device 5 → Indoor heat exchanger 2 → Four-way valve E port) Port → Four-way valve S interface → Compressor 1 low-pressure suction port 1b); Since the refrigerant separation in the second gas-liquid separator 14 is not completely absolute, the two branches after the second gas-liquid separator 14 do not only flow with a single pure refrigerant. At the same time, the low-temperature refrigerant is throttled in two stages before and after the first gas-liquid separator 7 to form liquid flash separation. The refrigerant gas (mainly low-temperature refrigerant gas) in the first gas-liquid separator 7 will also enter the medium-pressure enthalpy boosting gas injection port 1c of the compressor 1 through the three-way valve M interface and O interface channel.

[0065] Heating mode: Compressor 1 → Four-way valve D port → Four-way valve E port → Indoor heat exchanger 2 → First one-way valve 6 and / or first throttling device 5 → First gas-liquid separator 7 → (High-temperature refrigerant: Second throttling device 8 → First heat exchange channel 91 of condenser indoor heat exchanger 2 → Three-way valve N port → Three-way valve O port → Compressor 1 medium-pressure enthalpy boosting gas injection port 1c; Low-temperature refrigerant: Second heat exchange channel 92 of condenser indoor heat exchanger 2 → Third throttling device 10 → Second gas-liquid separator 14 → Fourth throttling device 15 → Outdoor heat exchanger 3 → Four-way valve C port Port → Four-way valve S interface → Compressor 1 low-pressure suction port 1b); Since the refrigerant separation in the first gas-liquid separator 7 is not completely absolute, the two branches after the first gas-liquid separator 7 do not only flow with a single pure refrigerant. At the same time, the low-temperature refrigerant is throttled in two stages before and after the second gas-liquid separator 14 to form liquid flash separation. The refrigerant gas (mainly low-temperature refrigerant gas) in the second gas-liquid separator 14 will also enter the medium-pressure enthalpy boosting gas injection port 1c of the compressor 1 through the three-way valve N interface and O interface channel.

[0066] Because both the front and rear sides of the first gas-liquid separator 7 and the second gas-liquid separator 14 are equipped with throttling devices, the refrigerant can undergo liquid flash separation within the gas-liquid separator. In this case, the gas-liquid separator is equivalent to a flash evaporator.

[0067] The self-cascade heat pump system of this invention employs a gas-injecting enthalpy-increasing compressor 1, using a medium-pressure enthalpy-increasing gas injection port 1c as the intake port for high-temperature refrigerant gas. Simultaneously, a three-way valve 13 switches the connection between the gas injection port 1c and the first flow channel 11 and the second flow channel 12 in different modes, ensuring that the medium-pressure enthalpy-increasing gas injection port 1c primarily returns high-temperature refrigerant gas, while the low-pressure intake port 1b of the compressor 1 primarily returns low-temperature refrigerant gas. This achieves low-pressure separation of the two refrigerants, ensuring operational reliability under different operating modes. Furthermore, it simplifies the system's control valves and system components, ensuring effective low-pressure separation of the two refrigerants in different modes and guaranteeing the system's capacity output. It solves the problem of gas-liquid separation and circulation of high-temperature and low-temperature refrigerants, improving the reliability of the circulation operation.

[0068] Furthermore, since the three-way valve 13 and the four-way valve 4 only require a single control port signal for control, the hardware and software design of the controller can be simplified, reducing costs and improving system reliability. Additionally, to prevent refrigerant liquid from entering the compressor suction port 1b after heating up when the system is shut down, all throttling devices, such as the expansion valve, are adjusted to their maximum opening after compressor 1 stops. This ensures that the refrigerant liquid is interconnected between the indoor heat exchanger 2, the outdoor heat exchanger 3, the first gas-liquid separator 7, and the second gas-liquid separator 14, serving as backup liquid storage spaces for each other. This prevents refrigerant liquid from being forced into the compressor 1 suction port, thus ensuring the reliable restart operation of compressor 1.

[0069] This utility model also provides an air conditioner that may include any of the above-mentioned self-cascading heat pump systems. Because the air conditioner uses the aforementioned self-cascading heat pump system, the output of the heating and cooling capacity of the self-cascading heat pump system can be improved.

[0070] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0071] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model. The above description is only a preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A self-cascade heat pump system, characterized by: The system includes a compressor (1), an indoor heat exchanger (2), an outdoor heat exchanger (3), a condenser-evaporator (9), a first gas-liquid separator (7), and a second gas-liquid separator (14); the compressor (1) has an intake port (1b), an exhaust port (1a), and a make-up air port (1c); the exhaust port (1a) is selectively connected to one of the two ends (21) of the indoor heat exchanger and one of the two ends (31) of the outdoor heat exchanger, and the other of the two ends (21) of the indoor heat exchanger and one of the two ends (31) of the outdoor heat exchanger is connected to the intake port (1b); The first gas-liquid separator (7) has a first A-flow port (71), a second A-flow port (72), and a first gas outlet (73); the second gas-liquid separator (14) has a first B-flow port (141), a second B-flow port (142), and a second gas outlet (143); the condenser-evaporator (9) has a first heat exchange channel (91) and a second heat exchange channel (92) that can exchange heat with each other; the other end (22) of the indoor heat exchanger is connected to the first A-flow port (71) through a first throttling device (5), and the second A-flow port (72) is connected to one end (911) of the first heat exchange channel through a second throttling device (8); the other end of the first heat exchange channel (912) and the second air outlet (143) are connected, and both are connected to the air supply port (1c) through the first flow channel (11); one end (921) of the second heat exchange channel is connected to the first air outlet (73), and both are connected to the air supply port (1c) through the second flow channel (12); the other end (922) of the second heat exchange channel is connected to the second B flow port (142) through the third throttling device (10), and the first B flow port (141) is connected to the other end (32) of the outdoor heat exchanger through the fourth throttling device (15); wherein, both the first flow channel (11) and the second flow channel (12) can be opened or closed.

2. The auto-cascade heat pump system of claim 1, wherein: The self-cascaded heat pump system has a heating mode and a cooling mode; In the heating mode, the exhaust port (1a) is connected to one end (21) of the indoor heat exchanger, and the first flow channel (11) is open and the second flow channel (12) is closed; in the cooling mode, the exhaust port (1a) is connected to one end (31) of the outdoor heat exchanger, and the first flow channel (11) is closed and the second flow channel (12) is open.

3. The self-cascading heat pump system according to claim 1 or 2, characterized in that: The first flow channel (11), the second flow channel (12), and the air supply port (1c) are connected by a three-way valve (13); Both the first flow channel (11) and the second flow channel (12) are opened or closed by the three-way valve (13).

4. The auto-cascade heat pump system of claim 3, wherein: It also includes a controller and a four-way valve (4); the air intake (1b), the exhaust port (1a), one end (21) of the indoor heat exchanger and one end (31) of the outdoor heat exchanger are connected to the four ports of the four-way valve (4) in a one-to-one correspondence, so that the exhaust port (1a) can be selectively connected to one of the two ends (21) of the indoor heat exchanger and one end (31) of the outdoor heat exchanger through the four-way valve (4), and the other one of the two ends is connected to the air intake (1b) through the four-way valve (4); The four-way valve (4) and the three-way valve (13) are both connected to the same signal port of the controller.

5. The self-cascading heat pump system according to claim 4, characterized in that: The four-way valve (4) has a C port, an S port, an E port and a D port. The four-way valve (4) is connected to one end (31) of the outdoor heat exchanger through the C port, and to the air intake (1b) through the S port, and to one end (21) of the indoor heat exchanger through the E port, and to the exhaust port (1a) through the D port. The three-way valve (13) has an O port, an M port and a N port. The three-way valve (13) is connected to the air supply port (1c) through the O port, and to the second flow channel (12) through the M port, and to the first flow channel (11) through the N port. In the first state, the three-way valve (13) controls the O port to be connected only to the M port between the M port and the N port, and the four-way valve (4) controls the D port to be connected to the C port and the S port to be connected to the E port. In the second state, the three-way valve (13) controls the O port to be connected only to the N port between the M port and the N port, and the four-way valve (4) controls the D port to be connected to the E port and the S port to be connected to the C port. In this state, one of the first state and the second state is a power-off state and the other is a power-on state. The controller switches the three-way valve (13) and the four-way valve (4) to the first state or the second state through the signal port.

6. The self-cascading heat pump system according to any one of claims 1-2 and 4-5, characterized in that: The first throttling device (5) has a first A end (51) and a second A end (52). The first throttling device (5) is connected to the other end (22) of the indoor heat exchanger through the first A end (51) and is connected to the first A outlet (71) through the second A end (52). The first throttling device (5) has a first check valve (6) connected in parallel at both ends. The first check valve (6) has an inlet A and an outlet A. The first check valve (6) is connected to the first A end (51) through the inlet A and to the second A end (52) through the outlet A.

7. The self-cascading heat pump system according to any one of claims 1-2 and 4-5, characterized in that: The fourth throttling device (15) has a first B end (151) and a second B end (152). The fourth throttling device (15) is connected to the other end (32) of the outdoor heat exchanger through the first B end (151) and is connected to the first B outlet (141) through the second B end (152). The fourth throttling device (15) has a second check valve (16) connected in parallel at both ends. The second check valve (16) has an inlet B and an outlet B. The second check valve (16) is connected to the first end B (151) through the inlet B and to the second end B (152) through the outlet B.

8. The self-cascading heat pump system according to any one of claims 1-2 and 4-5, characterized in that: The first throttling device (5), the second throttling device (8), the third throttling device (10) and the fourth throttling device (15) are all throttling valves; When the self-cascade heat pump system is shut down, the opening degree of the first throttling device (5), the second throttling device (8), the third throttling device (10) and the fourth throttling device (15) is the maximum opening degree.

9. The self-cascading heat pump system according to any one of claims 1-2 and 4-5, characterized in that: The refrigerant circulating in the self-cascade heat pump system is a non-azeotropic refrigerant, which is a refrigerant composed of two or more refrigerants with different boiling points.

10. An air conditioner characterized by comprising: The self-cascading heat pump system includes any one of claims 1-9.

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