Heat pump air conditioning system and control method thereof

Abstract

The present application relates to the field of rail transit (subway) vehicle air conditioning design and manufacturing technology, in particular to a heat pump air conditioning system and a control method thereof. The heat pump air conditioning system comprises a first system and a second system working independently, a first outdoor heat exchanger and a second outdoor heat exchanger are connected in parallel, a third outdoor heat exchanger and a fourth outdoor heat exchanger are connected in parallel; the first outdoor heat exchanger is connected in series with a first indoor heat exchanger, the second outdoor heat exchanger is connected in series with a second indoor heat exchanger; the third outdoor heat exchanger is connected in series with the first indoor heat exchanger, and the fourth outdoor heat exchanger is connected in series with the second indoor heat exchanger. The present application further provides a heat pump air conditioning system control method, which is applied to the heat pump air conditioning system. Compared with the prior art, the present application has the advantages that the first system and the second system can alternately operate in refrigeration and heating, thereby keeping the indoor temperature of the rail transit vehicle stable and improving the passenger experience.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rail transit (subway) vehicle air conditioning design and manufacturing technology, in particular to a heat pump air conditioning system and a control method thereof. BACKGROUND

[0002] The existing heat pump air conditioning system performs heating in winter, and when applied to rail transit, especially in subways, the subway air conditioner has a requirement for fresh air volume, that is, the supply air cannot be stopped. The conventional defrosting method needs to reverse the valve to change from heating to refrigeration, and during defrosting, the supply air temperature will continuously decrease until the defrosting is completed and a period of time is delayed before the supply air temperature is increased. Passengers will feel cold and uncomfortable during defrosting in winter, and even complaints. SUMMARY

[0003] Therefore, in view of the above technical problems, the present application provides a heat pump air conditioning system in an embodiment.

[0004] In order to solve the above technical problems, the present application provides the following technical solutions in an embodiment.

[0005] A heat pump air conditioning system, comprising a first system and a second system working independently; the first system comprises a first outdoor heat exchanger, a second outdoor heat exchanger and a first indoor heat exchanger; the second system comprises a third outdoor heat exchanger, a fourth outdoor heat exchanger and a second indoor heat exchanger; the first outdoor heat exchanger and the second outdoor heat exchanger are connected in parallel, the third outdoor heat exchanger and the fourth outdoor heat exchanger are connected in parallel; the first outdoor heat exchanger is connected in series with the first indoor heat exchanger, and the second outdoor heat exchanger is connected in series with the second indoor heat exchanger; the third outdoor heat exchanger is connected in series with the first indoor heat exchanger, and the fourth outdoor heat exchanger is connected in series with the second indoor heat exchanger.

[0006] It can be understood that the present application comprises the first system and the second system working independently, so that the first system and the second system can alternately operate in refrigeration and heating, thereby keeping the indoor temperature of the rail transit vehicle stable and preventing passengers from experiencing poor comfort due to excessively high or low temperature.

[0007] In one embodiment, the first outdoor heat exchanger and the second outdoor heat exchanger correspond to a first fan, the third outdoor heat exchanger and the fourth outdoor heat exchanger correspond to a second fan, a blocking piece is arranged between the first fan and the second fan, the blocking piece can prevent air from flowing between the first fan and the second fan, and when the system defrosts, the fan corresponding to the system stops, and the blocking piece enables the system to simultaneously perform heating and defrosting.

[0008] It can be understood that by arranging the barrier between the first fan and the second fan, the first fan and the second fan are prevented from being too close to each other, and the phenomenon of fighting for wind is avoided, and the phenomenon of fighting for wind is alleviated after the first fan and the second fan are physically isolated.

[0009] In one of the embodiments, the first indoor heat exchanger comprises a first flow passage and a second flow passage, the first flow passage is connected to the first outdoor heat exchanger, and the second flow passage is connected to the first flow passage; the second indoor heat exchanger comprises a third flow passage and a fourth flow passage, the fourth flow passage is connected to the second outdoor heat exchanger, and the third flow passage is connected to the fourth flow passage; the first indoor heat exchanger comprises a fifth flow passage and a sixth flow passage, the fifth flow passage is connected to the third outdoor heat exchanger, and the sixth flow passage is connected to the fifth flow passage; the second indoor heat exchanger comprises a seventh flow passage and an eighth flow passage, the eighth flow passage is connected to the fourth outdoor heat exchanger, and the seventh flow passage is connected to the eighth flow passage; the circuit in which the first flow passage and the second flow passage are located is not connected to the circuit in which the fifth flow passage and the sixth flow passage are located; and the circuit in which the third flow passage and the fourth flow passage are located is not connected to the circuit in which the seventh flow passage and the eighth flow passage are located.

[0010] It can be understood that by arranging the circuit in which the first flow passage and the second flow passage are located to be not connected to the circuit in which the fifth flow passage and the sixth flow passage are located, the first system and the second system are allowed to operate independently of each other.

[0011] In one of the embodiments, the first system comprises a first dry filter and a first sight glass, the first dry filter is connected between the first flow passage and the first outdoor heat exchanger, and the first sight glass is connected between the fourth flow passage and the second outdoor heat exchanger; the second system comprises a second dry filter and a second sight glass, the second dry filter is connected between the eighth flow passage and the fourth outdoor heat exchanger, and the second sight glass is connected between the fifth flow passage and the third outdoor heat exchanger; wherein the length of the pipeline between the first indoor heat exchanger and the first outdoor heat exchanger is shorter than the length of the pipeline between the first indoor heat exchanger and the third outdoor heat exchanger; and the length of the pipeline between the second indoor heat exchanger and the fourth outdoor heat exchanger is shorter than the length of the pipeline between the second indoor heat exchanger and the second outdoor heat exchanger.

[0012] It can be understood that, by arranging the first and second dry filters on the side of the system with relatively short pipe length, and arranging the first and second sight glasses on the side of the system with relatively long pipe length, the system is more balanced due to the relatively large resistance of the first and second dry filters to the first and second sight glasses.

[0013] In one of the embodiments, the first system comprises a first compressor, a first check valve, a first detection valve and a first pressure detection element, the first check valve is connected to the outlet of the first compressor, and the first detection valve and the first pressure detection element are arranged at the outlet of the first check valve; the second system comprises a second compressor, a second check valve, a second detection valve and a second pressure detection element, the second check valve is connected to the outlet of the second compressor, and the second detection valve and the second pressure detection element are arranged at the outlet of the second check valve.

[0014] It can be understood that, by arranging the detection valve and the pressure detection element at the outlet of the check valve, the misjudgment of system failure is avoided.

[0015] In one of the embodiments, the first system comprises a first compressor, a first gas-liquid separator and a first reversing valve, the first compressor is connected to the first check valve, the first gas-liquid separator is connected between the first compressor and the S port of the first reversing valve, the D port of the first reversing valve is connected to the first detection valve, the E port of the first reversing valve is connected to the second flow-through port and the third flow-through port respectively, and the C port of the first reversing valve is connected to the first outdoor heat exchanger and the second outdoor heat exchanger respectively; the second system comprises a second compressor, a second gas-liquid separator and a second reversing valve, the second compressor is connected to the second check valve, the second gas-liquid separator is connected between the second compressor and the S port of the second reversing valve, the D port of the second reversing valve is connected to the second detection valve, the E port of the second reversing valve is connected to the sixth flow-through port and the seventh flow-through port respectively, and the C port of the second reversing valve is connected to the third outdoor heat exchanger and the fourth outdoor heat exchanger respectively.

[0016] It can be understood that, by arranging the first and second reversing valves to be frequency conversion electromagnetic four-way valves, the gap between the slider and the shell in the first and second reversing valves is reduced, and the slider can slide in place in the shell even under small pressure difference.

[0017] In one of the embodiments, the first system comprises a first throttling valve and a second throttling valve, the first throttling valve is connected between the first dry filter and the first flow-through port, and the second throttling valve is connected between the first sight glass and the fourth flow-through port; the second system comprises a third throttling valve and a fourth throttling valve, the third throttling valve is connected between the fifth flow-through port and the second sight glass, and the fourth throttling valve is connected between the eighth flow-through port and the second dry filter.

[0018] It can be understood that, by arranging four throttling valves in the heat pump air conditioning system, the throttling valves can be arranged close to the evaporator respectively, so that the phenomenon of flash evaporation in the long distance from the indoor heat exchanger to the throttling valve and the decrease of refrigerating capacity can be avoided, and the liquid pipe after condensation of the outdoor heat exchanger can be further cooled before entering the throttling valve, so that the supercooling degree is increased.

[0019] In one of the embodiments, the first system comprises a second temperature sensor arranged at a branch port between the C port of the first reversing valve and the first outdoor heat exchanger and the second outdoor heat exchanger; and the second system comprises a fourth temperature sensor arranged at a branch port between the C port of the second reversing valve and the third outdoor heat exchanger and the fourth outdoor heat exchanger.

[0020] It can be understood that, by arranging the temperature sensor at the branch port between the reversing valve and the two outdoor heat exchangers, the cost is reduced.

[0021] In one of the embodiments, the first indoor heat exchanger and the second indoor heat exchanger correspond to a first air supply fan and a second air supply fan respectively, and the first air supply fan and the second air supply fan are variable frequency fans.

[0022] It can be understood that, by arranging the first air supply fan and the second air supply fan as variable frequency fans, the air volume of the air supply fan can be reduced when the load of the passengers in the vehicle is small, so that the noise is reduced, the comfort of the human body is improved, and the energy consumption is saved.

[0023] In one of the embodiments of the application, the following technical solutions are further provided:

[0024] A heat pump air conditioning system control method, the control method of the heat pump air conditioner is applied to a heat pump air conditioning system, and the method comprises the following steps: detecting the temperature T at a target position and comparing the temperature T with a first preset temperature Ts; if T≤Ts, the system starts a defrosting mode, and the other system starts a heating mode; and if T>Ts, the system stops the defrosting mode.

[0025] It can be understood that by using the heat pump air conditioning system control method, the operation energy consumption of the system can be reduced.

[0026] Compared with the prior art, the heat pump air conditioning system provided in the embodiment of the present application can realize that the first system and the second system can alternately operate for refrigeration and heating by making the heat pump air conditioning system include the first system and the second system which operate independently, thereby keeping the indoor temperature of the rail transit vehicle stable and not causing poor passenger experience due to excessively high or low temperature. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A schematic diagram of the principle of the heat pump air conditioning system provided in the present application is shown in the figure;

[0028] Figure 2 A schematic diagram of the structure of the first indoor heat exchanger provided in the present application is shown in the figure;

[0029] Figure 3 A schematic diagram of the structure of the second indoor heat exchanger provided in the present application is shown in the figure;

[0030] Figure 4 A schematic diagram of the structure of the first indoor heat exchanger provided in the present application is shown in the figure; Figure 1 A partial enlarged schematic diagram of A in the figure;

[0031] Figure 5 A partial enlarged schematic diagram of B in the figure; Figure 1 A partial enlarged schematic diagram of B in the figure;

[0032] The meanings of the symbols in the figure are as follows:

[0033] 100. Heat pump air conditioning system; 10. First system; 11. First outdoor heat exchanger; 111. Second outdoor heat exchanger; 12. First indoor heat exchanger; 121. First flow port; 122. Second flow port; 123. Fifth flow port; 124. Sixth flow port; 125. First blower; 13. First blower; 14. First filter drier; 141. First sight glass; 15. First one-way valve; 151. First detection valve; 152. First pressure detection element; 16. First compressor; 161. First gas-liquid separator; 17. First reversing valve; 18. First throttle valve; 181. Second throttle valve; 19. First temperature sensor; 191. Second Temperature sensor; 20. Second system; 21. Third outdoor heat exchanger; 211. Fourth outdoor heat exchanger; 22. Second indoor heat exchanger; 221. Third flow port; 222. Fourth flow port; 223. Seventh flow port; 224. Eighth flow port; 225. Second air blower; 23. Second air blower; 24. Second drying filter; 241. Second sight glass; 25. Second one-way valve; 251. Second detection valve; 252. Second pressure detection element; 26. Second compressor; 261. Second gas-liquid separator; 27. Second reversing valve; 28. Third throttle valve; 281. Fourth throttle valve; 29. ​​Third temperature sensor; 291. Fourth temperature sensor. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0035] It should be noted that when a component is referred to as being "mounted on" another component, it may be directly on the other component or there may also be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a central component. When a component is considered to be "fixed to" another component, it may be directly fixed on the other component or there may also be a central component. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] Referring to Figures 1 to 5 In an embodiment of the present application, a heat pump air conditioning system 100 is provided, which is applied to a rail transit vehicle and used for refrigeration or heating in the vehicle cabin. In other embodiments, the heat pump air conditioning system 100 can also be used in shopping malls, residences, and the like.

[0038] In the existing heat pump air conditioning system, the air conditioner performs heating in winter. Since the subway air conditioner requires a new air volume, i.e., the supply air cannot be stopped. The conventional defrosting mode needs to reverse the valve to change from heating to refrigeration. During defrosting, the supply air temperature will continuously decrease until the defrosting is completed and a certain period of time is delayed, and then the supply air temperature will be increased. Passengers will feel cold and uncomfortable during defrosting in winter, and even complaints.

[0039] To solve the problems existing in the existing heat pump air conditioning system, in an embodiment of the present application, a heat pump air conditioning system 100 is provided, which includes a first system 10 and a second system 20 working independently; the first system 10 includes a first outdoor heat exchanger 11, a second outdoor heat exchanger 111, and a first indoor heat exchanger 12; the second system 20 includes a third outdoor heat exchanger 21, a fourth outdoor heat exchanger 211, and a second indoor heat exchanger 22; the first outdoor heat exchanger 11 and the second outdoor heat exchanger 111 are connected in parallel, and the third outdoor heat exchanger 21 and the fourth outdoor heat exchanger 211 are connected in parallel; the first outdoor heat exchanger 11 is connected in series with the first indoor heat exchanger 12, and the second outdoor heat exchanger 111 is connected in series with the second indoor heat exchanger 22; the third outdoor heat exchanger 21 is connected in series with the first indoor heat exchanger 12, and the fourth outdoor heat exchanger 211 is connected in series with the second indoor heat exchanger 22.

[0040] In the present application, the heat pump air conditioning system 100 includes the first system 10 and the second system 20 working independently. When the heat pump air conditioning system 100 is defrosted, one system is refrigerated and the other system is heated. The indoor heat exchanger is connected with one of the outdoor heat exchangers of the first system 10 and the second system 20 under the heating and refrigeration systems, respectively. The cold capacity of refrigeration can be offset in the indoor heat exchanger, avoiding the phenomenon that the indoor supply air temperature is too low and the experience is poor caused by the traditional mode of separate defrosting. Thus, the first system 10 and the second system 20 can be alternately operated for refrigeration and heating, thereby keeping the indoor temperature of the rail transit vehicle stable and avoiding the poor experience of passengers caused by the excessively high or low temperature.

[0041] It is worth noting that the series connection and the parallel connection do not mean direct series connection or parallel connection, and other components of the heat pump air conditioning system are also provided therebetween.

[0042] Specifically, the first outdoor heat exchanger 11 and the second outdoor heat exchanger 111 correspond to a first fan 13, and the third outdoor heat exchanger 21 and the fourth outdoor heat exchanger 211 correspond to a second fan 23. If the first fan 13 and the second fan 23 are arranged too close to each other, wind stealing will occur. In particular, when the temperature is high, the first fan 13 and the second fan 23 directly blow air, and the processed air is sucked into the outdoor heat exchanger again, which makes the system condition worse. To solve this problem, a barrier is arranged between the first fan 13 and the second fan 23. After physically isolating the first fan 13 and the second fan 23, the phenomenon of wind stealing can be alleviated, and the problem of air blowing caused by wind stealing can be solved.

[0043] At the same time, the first outdoor heat exchanger 11 and the second outdoor heat exchanger 111 correspond to a first fan 13, and the third outdoor heat exchanger 21 and the fourth outdoor heat exchanger 211 correspond to a second fan 23. When the heat pump air conditioning system 100 is in low-load heating, one system and / or the corresponding condenser fan of one system can be turned off, thereby reducing energy consumption and improving energy efficiency.

[0044] In the embodiment, the barrier is a partition. Of course, in other embodiments, the barrier can also have other structures, as long as it can block the wind between the first fan 13 and the second fan 23, which is not limited here.

[0045] It should be noted that the heat pump air conditioning system 100 provided by the present application provides a first system 10 and a second system 20 that work independently, which is to solve the problem that the temperature in the vehicle cabin is too low during defrosting of the existing heat pump air conditioning system, causing passengers to feel uncomfortable. Generally, when the weather is cold, the heat pump air conditioning system 100 heats the vehicle cabin. At this time, the outdoor heat exchanger is in an evaporative heat absorption state, and the refrigerant in the outdoor heat exchanger is in a low-temperature state. The condenser above the condenser will freeze into crystals, and in severe cases, the outdoor heat exchanger may also be damaged. Therefore, the outdoor heat exchanger needs to be defrosted every certain period of time, and the vehicle cabin needs to be cooled at this time, so that the refrigerant in the outdoor condenser is at a high temperature to eliminate the ice and frost on the outdoor heat exchanger. However, when the weather is cold, cooling the vehicle cabin will undoubtedly make the people inside feel cold and cause discomfort.

[0046] To solve this problem, the first system 10 and the second system 20 that work independently can realize one system cooling and one system heating. That is, before the heat pump air conditioning system 100 needs to be defrosted, one system is ensured to be in a heating state, and then the other system is started to defrost. The refrigerant in the vehicle cabin heat exchanger exchanges heat, so that the cold and hot air cancel each other out, thereby maintaining the temperature balance in the vehicle cabin, and the passengers in the vehicle cabin will not feel too cold and uncomfortable.

[0047] It is worth noting that the heat pump air conditioning system 100 provided by the present application can be used in any situation to balance the temperature in the vehicle cabin, not just when defrosting is needed in low temperature. For example, when one system is heating and the temperature in the vehicle cabin is too high, the other system can be started in cooling mode to balance the temperature in the vehicle cabin. When one system is cooling and the temperature in the vehicle cabin is too low, the other system can be started in heating mode to balance the temperature in the vehicle cabin.

[0048] As shown in Figures 1 to 3 The first system 10 includes a first indoor heat exchanger 12, a first outdoor heat exchanger 11 and a second outdoor heat exchanger 111. The first indoor heat exchanger 12 includes a first flow passage 121 and a second flow passage 122, the first flow passage 121 is connected to the first outdoor heat exchanger 11, and the second flow passage 122 is in communication with the first flow passage 121. The second indoor heat exchanger 22 includes a third flow passage 221 and a fourth flow passage 222, the fourth flow passage 222 is connected to the second outdoor heat exchanger 111, and the third flow passage 221 is in communication with the fourth flow passage 222. The first indoor heat exchanger 12 includes a fifth flow passage 123 and a sixth flow passage 124, the fifth flow passage 123 is connected to the third outdoor heat exchanger 21, and the sixth flow passage 124 is in communication with the fifth flow passage 123. The second indoor heat exchanger 22 includes a seventh flow passage 223 and an eighth flow passage 224, the eighth flow passage 224 is connected to the fourth outdoor heat exchanger 211, and the seventh flow passage 223 is in communication with the eighth flow passage 224. The circuit in which the first flow passage 121 and the second flow passage 122 are located is not communicated with the circuit in which the fifth flow passage 123 and the sixth flow passage 124 are located.

[0049] It is worth noting that the circuit in which the first flow passage 121 and the second flow passage 122 are located is not communicated with the circuit in which the fifth flow passage 123 and the sixth flow passage 124 are located. That is, the first system 10 and the second system 20 share the first indoor heat exchanger 12 and the second indoor heat exchanger 22, but the first system 10 and the second system 20 form different circuits in the first indoor heat exchanger 12 and the second indoor heat exchanger 22, that is, the first system 10 and the second system 20 are independently controlled and independently work, so as to realize one system cooling and one system heating, so as to maintain the temperature balance in the vehicle cabin. Similarly, the circuit in which the third flow passage 221 and the fourth flow passage 222 are located is not communicated with the circuit in which the seventh flow passage 223 and the eighth flow passage 224 are located.

[0050] Further, the first system 10 comprises a first compressor 16, a first gas-liquid separator 161 and a first reversing valve 17. The first gas-liquid separator 161 is connected between the first compressor 16 and the S port of the first reversing valve 17, the D port of the first reversing valve 17 is connected to the first compressor 16, the E port of the first reversing valve 17 is connected to the second flow passage 122 and the third flow passage 221 respectively, and the C port of the first reversing valve 17 is connected to the first outdoor heat exchanger 11 and the second outdoor heat exchanger 111 respectively; the second system 20 comprises a second compressor 26, a second gas-liquid separator 261 and a second reversing valve 27. The second gas-liquid separator 261 is connected between the second compressor 26 and the S port of the second reversing valve 27, the D port of the second reversing valve 27 is connected to the second compressor 26, the E port of the second reversing valve 27 is connected to the sixth flow passage 124 and the seventh flow passage 223 respectively, and the C port of the second reversing valve 27 is connected to the third outdoor heat exchanger 21 and the fourth outdoor heat exchanger 211 respectively. The first reversing valve 17 and the second reversing valve 27 are used for reversing connection of the pipelines of the first system 10 and the second system 20 respectively, so as to switch the cooling / heating mode of the first system 10 and the second system 20.

[0051] Preferably, the first reversing valve 17 and the second reversing valve 27 are both variable frequency electromagnetic four-way valves. There are two versions of four-way valves for different models. The difference between the so-called fixed frequency electromagnetic four-way valve and the variable frequency electromagnetic four-way valve mainly lies in the internal structure. Because the high and low pressure difference is not obvious when the variable frequency compressor operates at low frequency, the four-way valve is actuated by the pressure difference. When the variable frequency unit operates at low frequency, the pressure difference is not obvious, which easily causes the four-way valve to be stuck in the middle, resulting in unit failure. In the existing reversing valve, a fixed frequency four-way reversing valve is usually used. When the heat pump air conditioning system switches between cooling and heating, because the variable frequency compressor starts and operates at a low frequency, the high and low pressure difference is small, and the gap between the slider and the shell in the fixed frequency electromagnetic four-way valve is large, which will cause the four-way valve to be stuck and unable to actuate to the position, resulting in high pressure protection failure. To solve this problem, the first reversing valve 17 and the second reversing valve 27 in the embodiment are both variable frequency electromagnetic four-way valves. In this way, the gap between the slider and the shell of the four-way valve can be reduced, so that even a small pressure difference can actuate to the position without being stuck.

[0052] Further, the first system 10 comprises a first one-way valve 15. The first one-way valve 15 is arranged between the outlet position of the first compressor 16 and the first reversing valve 17; the second system 20 comprises a second one-way valve 25. The second one-way valve 25 is arranged between the outlet position of the second compressor 26 and the second reversing valve 27.

[0053] As shown in FIG. 1, the heat pump air conditioning system comprises a first system 10 and a second system 20. The first system 10 comprises a first compressor 16, a first single-acting valve 15, a first gas-liquid separator 161, a first reversing valve 17, a first outdoor heat exchanger 11 and a first indoor heat exchanger 12. The first single-acting valve 15 is arranged between the outlet position of the first compressor 16 and the first reversing valve 17. The first gas-liquid separator 161 is connected between the first compressor 16 and the S port of the first reversing valve 17. The D port of the first reversing valve 17 is connected to the first compressor 16. The E port of the first reversing valve 17 is connected to the second flow passage 122 and the third flow passage 221 respectively. The C port of the first reversing valve 17 is connected to the first outdoor heat exchanger 11 and the second outdoor heat exchanger 111 respectively. The first indoor heat exchanger 12 is connected to the second flow passage 122 and the third flow passage 221 respectively. Figure 3 and Figure 4As shown, a first pressure detection element 152 and a first detection valve 151 are sequentially arranged between the outlet of the first one-way valve 15 and the first reversing valve 17; a second pressure detection element 252 and a second detection valve 251 are sequentially arranged between the outlet of the second one-way valve 25 and the second reversing valve 27.

[0054] It should be noted that the first pressure detection element 152 and the first detection valve 151 are sequentially arranged at the outlet of the first one-way valve 15, and the second pressure detection element 252 and the second detection valve 251 are sequentially arranged at the outlet of the second one-way valve 25. Compared with the prior art in which the pressure detection element and the detection valve are usually arranged at the inlet of the one-way valve, the arrangement can avoid misjudgment of system failure. For example, when the drying filter in the air conditioning system is dirty and blocked, frequent on-off of the heat pump air conditioning system will cause all the refrigerant to be discharged to the outlet of the one-way valve. At this time, the pressure detection element is arranged at the inlet of the one-way valve, i.e. the pressure detection element is at the low pressure side, so it is not protected, which will cause the detection valve to output a low pressure state regardless of whether a low pressure or a high pressure is detected. This will make the maintenance personnel mistakenly think that there is fluorine leakage or fluorine deficiency, and then a large amount of refrigerant will be added to supplement the refrigerant. Such misjudgment may cause damage to the compressor.

[0055] Preferably, in the embodiment, the first pressure detection element 152 and the second pressure detection element 252 are both pressure switches / sensors.

[0056] Further, the first system 10 includes a first drying filter 14 and a first sight glass 141. The first drying filter 14 is connected between the first flow-through port 121 and the first outdoor heat exchanger 11, and the first sight glass 141 is connected between the fourth flow-through port 222 and the second outdoor heat exchanger 111. The second system 20 includes a second drying filter 24 and a second sight glass 241. The second drying filter 24 is connected between the eighth flow-through port 224 and the fourth outdoor heat exchanger 211, and the second sight glass 241 is connected between the fifth flow-through port 123 and the third outdoor heat exchanger 21.

[0057] In the embodiment, the length of the pipeline between the first indoor heat exchanger 12 and the first outdoor heat exchanger 11 is relatively shorter than the length of the pipeline between the first indoor heat exchanger 12 and the third outdoor heat exchanger 21. The length of the pipeline between the second indoor heat exchanger 22 and the fourth outdoor heat exchanger 211 is relatively shorter than the length of the pipeline between the second indoor heat exchanger 22 and the second outdoor heat exchanger 111.

[0058] It should be noted that, since the flow resistance of the refrigerant in the first and second dry filters 14 and 24 is relatively large compared with the flow resistance in the first and second sight glasses 141 and 241, in the present embodiment, the first and second dry filters 14 and 24 are arranged on the side of the system with relatively short pipe length, so that the system is more balanced by using the first and second dry filters 14 and 24 to balance the system resistance on the side of the system with relatively short pipe length compared with the first and second sight glasses 141 and 241.

[0059] Further, the first system 10 comprises a first throttling valve 18 and a second throttling valve 181, the first throttling valve 18 being connected between the first dry filter 14 and the first flow-through port 121, and the second throttling valve 181 being connected between the first sight glass 141 and the fourth flow-through port 222; the second system 20 comprises a third throttling valve 28 and a fourth throttling valve 281, the third throttling valve 28 being connected between the fifth flow-through port 123 and the second sight glass 241, and the fourth throttling valve 281 being connected between the eighth flow-through port 224 and the second dry filter 24.

[0060] It should be noted that, in the existing heat pump air conditioning system, the evaporator is usually arranged on both sides of the heat pump air conditioning unit with air supply at both ends, and the conventional two throttling valves are arranged in the middle of the heat pump air conditioning system, which may cause flash evaporation in the long distance from the throttling to the evaporator. Therefore, the heat pump air conditioning system 100 provided by the present application is arranged with four throttling valves, so that the throttling valves can be arranged close to the evaporator, avoiding the situation of flash evaporation in the long distance from the throttling to the evaporator, and being far away from the condenser. In this way, on the one hand, the heat dissipation in the liquid pipe after condensation in the condenser can be further increased to increase the supercooling degree, and on the other hand, since it is a heat pipe, it can not need to be wrapped with thermal insulation cotton, thereby reducing the use amount of thermal insulation cotton and reducing the material cost. In the present embodiment, the first throttling valve 18 is arranged close to the first indoor heat exchanger 12, the second throttling valve 181 is arranged close to the second indoor heat exchanger 22, the third throttling valve 28 is arranged close to the third outdoor heat exchanger 21, and the fourth throttling valve 281 is arranged close to the fourth outdoor heat exchanger 211.

[0061] Alternatively, the first and second throttling valves 18 and 181 can adopt electronic expansion valves or thermal expansion valves, which are not limited herein.

[0062] Further, the first system 10 comprises a first temperature sensor 19 and a second temperature sensor 191. The first temperature sensor 19 is arranged between the first compressor 16 and the first check valve 15, and the second temperature sensor 191 is arranged at the branch port between the C port of the first reversing valve 17 and the first outdoor heat exchanger 11 and the second outdoor heat exchanger 111. The second system 20 comprises a third temperature sensor 29 and a fourth temperature sensor 291. The third temperature sensor 29 is arranged between the second compressor 26 and the second check valve 25, and the fourth temperature sensor 291 is arranged at the branch port between the C port of the second reversing valve 27 and the third outdoor heat exchanger 21 and the fourth outdoor heat exchanger 211.

[0063] It should be noted that the conventional heat pump air conditioning system 100 needs to set a temperature sensor on the outdoor pipeline during the defrosting process. When the outdoor heat exchanger is set to four in the present embodiment, if the temperature sensor is set at the outlet end of the condenser, four temperature sensors need to be set to meet the requirements, which increases the material cost. To solve this problem, the position of the temperature sensor is changed in the present embodiment, and it is set at the branch port of the condenser inlet. At this time, only one temperature sensor needs to be set for one unit to meet the requirements, which greatly reduces the material cost.

[0064] Further, the first indoor heat exchanger 12 and the second indoor heat exchanger 22 are respectively provided with a first air supply fan 125 and a second air supply fan 225. The first air supply fan 125 and the second air supply fan 225 in the present embodiment are both variable frequency fans. In this way, when the load of the vehicle cabin is small, the air supply amount of the first air supply fan 125 and the second air supply fan 225 can be reduced, thereby reducing the noise and improving the human comfort.

[0065] Since the first system 10 and the second system 20 have the same structure, they can be used interchangeably.

[0066] The present embodiment also provides the following technical solutions:

[0067] A heat pump air conditioning system control method is applied to a heat pump air conditioning system 100. The method comprises: detecting the temperature T at the target position and comparing it with the first preset temperature Ts; if T≤Ts, the system starts the defrosting mode, and the other system starts the heating mode; if T>Ts, the system stops the defrosting mode.

[0068] It should be noted that when T≤Ts, it is proved that the heat pump air conditioning system 100 needs to be defrosted at this time, so when this condition is met, the system opens the defrosting mode, and the other system opens the heating mode; The case is divided into the second system 20 opening the heating mode, and the first system 10 opening the defrosting mode; Or, the first system 10 opens the heating mode, and the second system 20 opens the defrosting mode. When T> Ts, it is proved that the heat pump air conditioning system 100 does not need to be defrosted at this time, so when this condition is met, the system closes the defrosting mode, which is divided into closing the first system 10 or the second system 20, or even additionally closing the first system 10 or the second system 20. The first fan 13 or the second fan 23 corresponding to the first system 10 or the second system 20, thereby reducing the energy consumption and improving the unit energy efficiency at low load. In actual rail transit vehicle operation, long-time low-load operation is significant and has high usage rate.

[0069] For example, when the heat pump air conditioning system 100 needs to be defrosted, the second system 20 remains in the heating state, the second compressor 26 outputs high-temperature and high-pressure refrigerant through the second one-way valve 25, the second pressure detection element 252 and the second detection valve 251 into the D port of the second reversing valve 27, and then from the E port of the second reversing valve 27. Output to the first indoor heat exchanger 12 and the second indoor heat exchanger 22 to condense and release heat, and then flow out from the first indoor heat exchanger 12 and the second indoor heat exchanger 22, respectively, and pass through the third throttling valve 28, the second sight glass 241, and the fourth throttling valve 281, respectively. The second dry filter 24 enters the third outdoor heat exchanger 21 and the fourth outdoor heat exchanger 211, respectively, and then enters the C port of the second reversing valve 27 through the third outdoor heat exchanger 21 and the fourth outdoor heat exchanger 211. Finally, the refrigerant is output from the S port of the second reversing valve 27 to return to the second compressor 26 through the second gas-liquid separator 261, completing the heating cycle. At this time, the first system 10 starts to refrigerate and defrost, and the first compressor 16 outputs high-temperature and high-pressure refrigerant through the first one-way valve 15, the first pressure detection element 152 and the first detection valve 151 into the D port of the first reversing valve 17, and then from the C port of the first reversing valve 17. Output to the first outdoor heat exchanger 11 and the second outdoor heat exchanger 111 to condense into medium-temperature and high-pressure liquid, and then output from the first outdoor heat exchanger 11 and the second outdoor heat exchanger 111 through the first dry filter 14, the first throttling valve 18, and the first sight glass 141, respectively. The second throttling valve 181 enters the first indoor heat exchanger 12 and the second indoor heat exchanger 22, respectively, and then flows into the E port of the first reversing valve 17 through the first indoor heat exchanger 12 and the second indoor heat exchanger 22. Finally, the refrigerant is output from the S port of the first reversing valve 17 to return to the first compressor 16 through the first gas-liquid separator 161, completing the refrigeration cycle.

[0070] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, as long as there is no conflict, any combination of the technical features should be considered within the scope of the present disclosure.

[0071] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A heat pump air conditioning system, characterised in that, The system comprises a first system (10) and a second system (20) which work independently; The first system (10) comprises a first outdoor heat exchanger (11), a second outdoor heat exchanger (111) and a first indoor heat exchanger (12); The second system (20) comprises a third outdoor heat exchanger (21), a fourth outdoor heat exchanger (211) and a second indoor heat exchanger (22); The first outdoor heat exchanger (11) and the second outdoor heat exchanger (111) are connected in parallel, and the third outdoor heat exchanger (21) and the fourth outdoor heat exchanger (211) are connected in parallel; The first outdoor heat exchanger (11) is connected in series with the first indoor heat exchanger (12), and the second outdoor heat exchanger (111) is connected in series with the second indoor heat exchanger (22); The third outdoor heat exchanger (21) is connected in series with the first indoor heat exchanger (12), and the fourth outdoor heat exchanger (211) is connected in series with the second indoor heat exchanger (22); The first indoor heat exchanger (12) comprises a first flow passage (121) and a second flow passage (122), the first flow passage (121) is connected to the first outdoor heat exchanger (11), and the second flow passage (122) is connected to the first flow passage (121); the second indoor heat exchanger (22) comprises a third flow passage (221) and a fourth flow passage (222), the fourth flow passage (222) is connected to the second outdoor heat exchanger (111), and the third flow passage (221) is connected to the fourth flow passage (222); The first indoor heat exchanger (12) comprises a fifth flow passage (123) and a sixth flow passage (124), the fifth flow passage (123) is connected to the third outdoor heat exchanger (21), and the sixth flow passage (124) is connected to the fifth flow passage (123); the second indoor heat exchanger (22) comprises a seventh flow passage (223) and an eighth flow passage (224), the eighth flow passage (224) is connected to the fourth outdoor heat exchanger (211), and the seventh flow passage (223) is connected to the eighth flow passage (224); The circuit in which the first flow passage (121) and the second flow passage (122) are located is not connected to the circuit in which the fifth flow passage (123) and the sixth flow passage (124) are located; The circuit in which the third flow passage (221) and the fourth flow passage (222) are located is not connected to the circuit in which the seventh flow passage (223) and the eighth flow passage (224) are located; The first system (10) further comprises a first pressure detection element (152), which is a pressure switch / pressure sensor.

2. The heat pump air conditioning system of claim 1, wherein, The first outdoor heat exchanger (11) and the second outdoor heat exchanger (111) correspond to a first fan (13) together, the third outdoor heat exchanger (21) and the fourth outdoor heat exchanger (211) correspond to a second fan (23) together, and a barrier is arranged between the first fan (13) and the second fan (23), which can prevent air from being mixed between the first fan (13) and the second fan (23).

3. The heat pump air conditioning system of claim 2, wherein, The first system (10) comprises a first dry filter (14) and a first sight glass (141), the first dry filter (14) is connected between the first flow-through port (121) and the first outdoor heat exchanger (11), and the first sight glass (141) is connected between the fourth flow-through port (222) and the second outdoor heat exchanger (111); The second system (20) comprises a second dry filter (24) and a second sight glass (241), the second dry filter (24) is connected between the eighth flow-through port (224) and the fourth outdoor heat exchanger (211), and the second sight glass (241) is connected between the fifth flow-through port (123) and the third outdoor heat exchanger (21); The length of the pipeline between the first indoor heat exchanger (12) and the first outdoor heat exchanger (11) is shorter than the length of the pipeline between the first indoor heat exchanger (12) and the third outdoor heat exchanger (21), and the length of the pipeline between the second indoor heat exchanger (22) and the fourth outdoor heat exchanger (211) is shorter than the length of the pipeline between the second indoor heat exchanger (22) and the second outdoor heat exchanger (111).

4. The heat pump air conditioning system according to claim 3, wherein, The first system (10) comprises a first compressor (16), a first one-way valve (15) and a first detection valve (151), the first one-way valve (15) is connected to the outlet of the first compressor (16), and the first detection valve (151) and the first pressure detection element (152) are arranged at the outlet position of the first one-way valve (15). The second system (20) comprises a second compressor (26), a second one-way valve (25), a second detection valve (251) and a second pressure detection element (252), the second one-way valve (25) is connected to the outlet of the second compressor (26), and the second detection valve (251) and the second pressure detection element (252) are arranged at the outlet position of the second one-way valve (25).

5. The heat pump air conditioning system of claim 4, wherein, The first system (10) comprises a first compressor (16), a first gas-liquid separator (161) and a first reversing valve (17), the first compressor (16) is connected to the first check valve (15), the first gas-liquid separator (161) is connected between the first compressor (16) and the S port of the first reversing valve (17), the D port of the first reversing valve (17) is connected to the first detection valve (151), the E port of the first reversing valve (17) is connected to the second flow-through port (122) and the third flow-through port (221) respectively, and the C port of the first reversing valve (17) is connected to the first outdoor heat exchanger (11) and the second outdoor heat exchanger (111) respectively; The second system (20) comprises a second compressor (26), a second gas-liquid separator (261) and a second reversing valve (27), the second compressor (26) is connected to the second check valve (25), the second gas-liquid separator (261) is connected between the second compressor (26) and the S port of the second reversing valve (27), the D port of the second reversing valve (27) is connected to the second detection valve (251), the E port of the second reversing valve (27) is connected to the sixth flow-through port (124) and the seventh flow-through port (223) respectively, and the C port of the second reversing valve (27) is connected to the third outdoor heat exchanger (21) and the fourth outdoor heat exchanger (211) respectively.

6. The heat pump air conditioning system of claim 3, wherein, The first system (10) comprises a first throttling valve (18) and a second throttling valve (181), the first throttling valve (18) is connected between the first dry filter (14) and the first flow-through port (121), and the second throttling valve (181) is connected between the first sight glass (141) and the fourth flow-through port (222). The second system (20) comprises a third throttling valve (28) and a fourth throttling valve (281), the third throttling valve (28) is connected between the fifth flow-through port (123) and the second sight glass (241), and the fourth throttling valve (281) is connected between the eighth flow-through port (224) and the second dry filter (24).

7. The heat pump air conditioning system of claim 5, wherein, The first system (10) comprises a second temperature sensor (191), which is arranged at a branch port between the C port of the first reversing valve (17) and the first outdoor heat exchanger (11) and the second outdoor heat exchanger (111); The second system (20) comprises a fourth temperature sensor (291), which is arranged at a branch port between the C port of the second reversing valve (27) and the third outdoor heat exchanger (21) and the fourth outdoor heat exchanger (211).

8. The heat pump air conditioning system of claim 1, wherein, The first indoor heat exchanger (12) and the second indoor heat exchanger (22) correspond to a first air supply fan (125) and a second air supply fan (225) respectively, and the first air supply fan (125) and the second air supply fan (225) are variable frequency fans.

9. A heat pump air conditioning system control method characterized by, The heat pump air conditioning system control method is applied to the heat pump air conditioning system as claimed in claims 1-8, and the method comprises the following steps: detecting the temperature T at the target position and comparing it with the first preset temperature Ts; if T≤Ts, the system starts the defrosting mode and the other system starts the heating mode; if T>Ts, the system stops the defrosting mode.

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