Duct type air conditioner

Abstract

The utility model discloses a duct type air conditioner, and belongs to the technical field of air conditioners. The duct type air conditioner comprises a shell, the shell is provided with an air inlet and an air supply opening, the air inlet comprises a first indoor air return opening and an outdoor fresh air opening, the first indoor air return opening communicates with the air supply opening to form a first flowing path, and the outdoor fresh air opening communicates with the air supply opening to form a second flowing path; a first heat exchanger on the first flow path and the second flow path; a second heat exchanger located on the second flow path; the shell is further provided with a second indoor air return opening, and indoor air entering from the second indoor air return opening moves in the shell along a second flowing path. The duct type air conditioner further comprises an indoor expansion valve and an electromagnetic valve. In a refrigerant system of the duct type air conditioner, a liquid side stop valve, a first heat exchanger, an indoor expansion valve, a second heat exchanger and an air side stop valve are sequentially connected in series; the first heat exchanger and the indoor expansion valve form a first branch, and the electromagnetic valve is connected with the first branch in parallel. The duct type air conditioner has a fresh air function and can avoid condensation.

Description

Technical Field

[0001] This application relates to the technical field of air conditioners, and particularly to an air duct machine. Background Art

[0002] At present, most air duct machines do not have the function of introducing fresh air. There are roughly two forms of the few air duct machines with the fresh air function: one is to directly open a fresh air inlet on the outer shell of the air duct machine to communicate with the outdoor air; the other is to install a fresh air module on the air duct machine.

[0003] These air duct machines with the function of introducing fresh air all have the problem of condensation. Taking winter as an example, when the outdoor temperature is lower than -10°C, but the indoor temperature is relatively high, users need to introduce fresh air. At this time, condensation will occur when the introduced fresh air contacts the high-temperature and high-humidity indoor air. Utility Model Content

[0004] This application provides an air duct machine with a fresh air function and can avoid the occurrence of condensation.

[0005] On one hand of this application, an air duct machine includes: a housing, on which a first indoor air return opening, an outdoor fresh air inlet, and an air supply opening are provided; a first heat exchanger, disposed in the housing corresponding to the air supply opening, the windward side of the first heat exchanger is communicated with the indoor air return opening to form a first air inlet duct, and the windward side of the first heat exchanger is communicated with the outdoor fresh air inlet to form a second air inlet duct; a second heat exchanger, disposed in the second air inlet duct corresponding to the outdoor fresh air inlet;

[0006] Wherein, a second indoor air return opening is further provided on the housing, and the second indoor air return opening is communicated with the air inlet end of the second air inlet duct;

[0007] When the air duct machine introduces fresh air, the second heat exchanger can be used as a condenser during heating and as an evaporator during cooling.

[0008] On the other hand of this application, an air duct machine includes: a housing, on which an air inlet and an air supply opening are provided, the air inlet includes a first indoor air return opening and an outdoor fresh air inlet, the first indoor air return opening is communicated with the air supply opening to form a first flow path, and the outdoor fresh air inlet is communicated with the air supply opening to form a second flow path; a first heat exchanger, disposed in the housing corresponding to the air supply opening, the first heat exchanger is located on the first flow path and the second flow path; a second heat exchanger, disposed corresponding to the outdoor fresh air inlet, the second heat exchanger is located on the second flow path;

[0009] Wherein, a second indoor air return opening is further provided on the housing, and the indoor air entering from the second indoor air return opening moves along the second flow path in the housing;

[0010] The air duct unit further includes an indoor expansion valve and a solenoid valve; in the refrigerant system of the air duct unit, a liquid-side stop valve, a first heat exchanger, an indoor expansion valve, a second heat exchanger, and a gas-side stop valve are connected in series in sequence; the first heat exchanger and the indoor expansion valve form a first branch, and the solenoid valve is connected in parallel with the first branch.

[0011] In some embodiments, a partial space near the air inlet in the housing is an air inlet space;

[0012] The air duct unit further includes: a fan, disposed between the air inlet space and the first heat exchanger, for driving the flow of indoor air and outdoor fresh air;

[0013] A wind partition is provided in the housing, and the wind partition divides the air inlet space into a first air inlet space communicated with the first indoor air return opening, and a second air inlet space communicated with the outdoor fresh air opening and the second indoor air return opening; the second heat exchanger is disposed in the second air inlet space.

[0014] In some embodiments, there is a gap between the wind partition and the fan to form a mixed air space.

[0015] In some embodiments, the area of the second air inlet space is larger than the area of the first air inlet space.

[0016] In some embodiments, a tuyere flange is provided at the first indoor air return opening, and a plurality of knockout plates are stacked along the radial direction inside the tuyere flange.

[0017] In some embodiments, the first indoor air return opening, the outdoor fresh air opening, and the second indoor air return opening are located on the same side wall of the housing.

[0018] In some embodiments, in the refrigerant system, an outdoor expansion valve is connected in series between the outdoor heat exchanger and the liquid-side stop valve;

[0019] When the unit is in defrosting operation, the outdoor expansion valve is in a fully open state, the solenoid valve is in a closed state, the outdoor heat exchanger and the first heat exchanger are used as condensers, and the second heat exchanger is used as an evaporator;

[0020] The first indoor air return opening is in an open state, the outdoor fresh air opening and the second indoor air return opening are in closed states; the air duct unit allows indoor air to blow into the room through the first indoor air return opening and the first heat exchanger.

[0021] In some embodiments, in the refrigerant system, an outdoor expansion valve is connected in series between the outdoor heat exchanger and the liquid-side stop valve;

[0022] In the dehumidification mode, the outdoor expansion valve is in a fully open state, the solenoid valve is in a closed state, so that the outdoor heat exchanger and the first heat exchanger are used as condensers, and the second heat exchanger is used as an evaporator;

[0023] The first indoor air return opening is in a closed state, the outdoor fresh air inlet is in an open state during fresh air dehumidification, and the second indoor air return opening is in an open state during indoor dehumidification.

[0024] In some embodiments, in the mixed air mode, the first indoor air return opening and the outdoor fresh air inlet are in an open state, and the second indoor air return opening is in a closed state;

[0025] The solenoid valve is in a closed state, the indoor expansion valve is fully open, and both the second heat exchanger and the first heat exchanger act as evaporators during refrigeration and as condensers during heating. Description of the Drawings

[0026] Figure 1 A diagram showing the internal structure of an air duct machine according to some embodiments;

[0027] Figure 2 A side view showing the air outlet flange of an air duct machine according to some embodiments;

[0028] Figure 3 A diagram showing the refrigerant system of an air duct machine in the refrigeration / dehumidification mode according to some embodiments;

[0029] Figure 4 A diagram showing the refrigerant system of an air duct machine in the refrigeration mode according to some other embodiments;

[0030] Figure 5 A diagram showing the refrigerant system of an air duct machine in the heating mode according to some embodiments;

[0031] Figure 6 A diagram showing the refrigerant system of an air duct machine in the heating mode according to some other embodiments;

[0032] Figure 7 A diagram showing the air flow of an air duct machine in the fresh air mode according to some embodiments;

[0033] Figure 8 A diagram showing the air flow of an air duct machine in the return air mode according to some embodiments;

[0034] Figure 9 A diagram showing the air flow of an air duct machine in the mixed air mode according to some embodiments;

[0035] Figure 10 A diagram showing the air flow of an air duct machine during defrosting operation according to some embodiments.

[0036] In the above figures, 10 is the housing; 11 is the front side plate; 111 is the air supply opening; 12 is the rear side plate; 121 is the first indoor air return opening; 122 is the outdoor fresh air inlet; 123 is the second indoor air return opening; 13 is the left side plate; 14 is the right side plate; 15 is the air duct flange; 151 is the knockout plate; 1511 is the first layer knockout plate; 1512 is the second layer knockout plate; 16 is the air baffle; 171 is the first air inlet space; 172 is the second air inlet space; 21 is the first heat exchanger; 22 is the second heat exchanger; 23 is the indoor expansion valve; 24 is the solenoid valve; 30 is the fan; 40 is the filter screen; 51 is the compressor; 52 is the outdoor heat exchanger; 53 is the four-way valve; 54 is the outdoor expansion valve; 55 is the outdoor fan; 61 is the liquid side stop valve; 62 is the gas side stop valve. Detailed implementation manners

[0037] To make the objectives and implementation manners of this application clearer, the following will clearly and completely describe the exemplary implementation manners of this application with reference to the accompanying drawings in the exemplary embodiments of this application. Obviously, the described exemplary embodiments are only a part rather than all of the embodiments of this application.

[0038] In the description of this application, it should be understood that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this application.

[0039] The terms "first" and "second" are only used for descriptive purposes, and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise stated, the meaning of "plural" is two or more.

[0040] In the description of this application, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] The air duct machine in the implementation manner of this application belongs to a type of air conditioner.

[0042] An air conditioner performs a refrigeration cycle of the air conditioner by using a compressor, a condenser, an expansion valve, and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation, and supplies refrigerant to the air that has been conditioned and heat-exchanged.

[0043] The compressor compresses the refrigerant gas in a low-temperature and low-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0044] The expansion valve expands the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator can achieve a refrigeration effect by performing a heat exchange with the material to be cooled by using the latent heat of evaporation of the refrigerant. Throughout the cycle, the air conditioner can adjust the temperature of the indoor space.

[0045] The outdoor unit of the air conditioner refers to the part of the refrigeration cycle including the compressor and the outdoor heat exchanger. The indoor unit of the air conditioner includes an indoor heat exchanger, and the expansion valve can be provided in the indoor unit or the outdoor unit.

[0046] The indoor heat exchanger and the outdoor heat exchanger serve as condensers or evaporators. When the indoor heat exchanger serves as a condenser, the air conditioner serves as a heater in the heating mode. When the indoor heat exchanger serves as an evaporator, the air conditioner serves as a cooler in the cooling mode.

[0047] The duct machine has an indoor unit and an outdoor unit. The indoor unit is used to perform a heat exchange with the indoor air. For a duct machine with a fresh air function, the indoor unit is also used to perform a heat exchange with the outdoor fresh air. The outdoor unit is used to perform a heat exchange with the outdoor air.

[0048] Refer to Figure 1 , the indoor unit of the duct machine according to an embodiment of the present application includes a housing 10 having a first indoor air return opening 121 and an air supply opening 111.

[0049] The housing 10 may be in a cuboid shape, forming the overall appearance of the duct machine. The housing 10 includes a top plate constituting the top structure, a bottom plate constituting the bottom structure, and four side plates connected between the top plate and the bottom plate. Among them, the four side plates are a front side plate 11, a rear side plate 12, a left side plate 13, and a right side plate 14. The side plates can be made of sheet metal.

[0050] The first indoor air return opening 121 can be arranged on the rear side plate 12. The air supply opening 111 can be arranged on the front side plate 11. However, the embodiments of the present application are not limited thereto. The first indoor air return opening 121 can also be arranged at the front part of the bottom plate. The air supply opening 111 can also be arranged at the rear part of the bottom plate.

[0051] The first indoor air return opening 121 is communicated with the indoor space and is used for collecting indoor air into the housing 10.

[0052] The first indoor air return opening 121 can be rectangular and directly dock with the air inlet grille of the indoor ceiling to realize the communication between the first indoor air return opening 121 and the indoor air. Or, in other embodiments, the first indoor air return opening 121 is connected with an air outlet flange 15, and the air outlet flange 15 is communicated with the indoor air through an air duct.

[0053] The air supply opening 111 is communicated with the indoor space and is used for releasing air into the indoor space. The air supply opening 111 can be communicated with the indoor air through an air duct.

[0054] The housing 10 is also provided with an outdoor fresh air inlet 122, which is used for communicating with the outdoor air to collect the outdoor air into the housing 10.

[0055] The outdoor fresh air inlet 122 and the first indoor air return opening 121 can be arranged on the same wall of the housing 10. Exemplarily, the outdoor fresh air inlet 122 and the first indoor air return opening 121 are arranged side by side left and right and are provided on the rear side plate 12. It is equivalent to dividing the indoor air return opening of the original air duct machine without fresh air function into two, one of which still serves as the first indoor air return opening 121 and the other serves as the outdoor fresh air inlet 122.

[0056] In other embodiments, the outdoor fresh air inlet 122 and the first indoor air return opening 121 can be arranged on different walls of the housing 10. Exemplarily, the outdoor fresh air inlet 122 is arranged on the rear side plate 12, and the first indoor air return opening 121 is arranged at the rear part of the bottom plate.

[0057] An air outlet flange 15 is connected to the outdoor fresh air inlet 122, and the air outlet flange 15 is communicated with the outdoor air through an air duct.

[0058] The first indoor air return opening 121 and the air supply opening 111 are communicated to form a first flow path, and the outdoor fresh air inlet 122 and the air supply opening 111 are communicated to form a second flow path.

[0059] The housing 10 is provided with a second indoor air return opening 123, which is used for communicating with the indoor space so that the collected indoor air can enter the housing 10.

[0060] The flow path of the indoor air entering from the second indoor air return opening 123 in the housing 10 is the same as the flow path of the outdoor fresh air (the second flow path).

[0061] The second indoor air return opening 123 can be arranged adjacent to the outdoor fresh air inlet 122. A tuyere flange 15 is connected at the second indoor air return opening 123, and the tuyere flange 15 is communicated with the indoor air through an air duct.

[0062] For convenience of description, hereinafter, the first indoor air return opening 121, the second indoor air return opening 123 and the outdoor fresh air inlet 122 are collectively referred to as air inlets.

[0063] The air duct machine may include a first heat exchanger 21. The first heat exchanger 21 can be arranged inside the housing 10 and can be arranged on the air movement path from the air inlet to the air outlet 111. Exemplarily, the first heat exchanger 21 can be arranged closer to the air outlet 111 inside the housing 10. The first heat exchanger 21 is used to absorb heat from the air introduced into the air inlet or transfer heat to the air. The first heat exchanger 21 is located on the first flow path and the second flow path, so that the indoor air can pass through the first heat exchanger 21, and the indoor fresh air can also pass through the first heat exchanger 21.

[0064] The air duct machine may include a fan 30. The fan 30 is arranged inside the housing 10 and is used to drive the air flow, so that the indoor air flows from the first indoor air return opening 121 to the air outlet 111, so that the outdoor fresh air flows from the outdoor fresh air inlet 122 to the air outlet 111, and so that the indoor air flows from the second indoor air return opening 123 to the air outlet 111.

[0065] The fan 30 can be arranged on the windward side of the first heat exchanger 21, that is, between the air inlet and the first heat exchanger 21. The fan 30 can adopt a centrifugal fan, which has the characteristics of large air volume and small volume.

[0066] When the indoor-outdoor temperature difference is large, condensation may occur when the outdoor fresh air is introduced by the fan 30 and contacts the indoor air. To solve this technical problem, a second heat exchanger 22 is introduced in the embodiments of the present application.

[0067] The second heat exchanger 22 is arranged in the housing 10 corresponding to the outdoor fresh air inlet 122 and the second indoor air return opening 121. The second heat exchanger 22 is located on the second flow path.

[0068] The outdoor fresh air introduced from the outdoor fresh air inlet 122 will pass through the second heat exchanger 22 and the first heat exchanger 21 when flowing in the housing 10; the indoor air introduced from the second indoor air return opening 123 will pass through the second heat exchanger 22 and the first heat exchanger 21 when flowing in the housing 10; the indoor air introduced from the first indoor air return opening 121 will not pass through the second heat exchanger 22 and only pass through the first heat exchanger 21 when flowing in the housing 10.

[0069] When the second heat exchanger 22 is used as an evaporator, it can cool the outdoor fresh air, and when the second heat exchanger 22 is used as a condenser, it can heat the outdoor fresh air.

[0070] Therefore, in the embodiments of the present application, after the outdoor fresh air enters the housing 10 from the outdoor fresh air inlet 122, it is heated / cooled by the second heat exchanger 22, thereby reducing the temperature difference between the indoor air and the outdoor fresh air and avoiding the condensation problem.

[0071] Compared with the air duct machine models without the fresh air function, in the embodiments provided by the present application, the distance between the fan 30 and the air inlet is increased to facilitate the installation of the second heat exchanger 22 in this space.

[0072] According to the embodiments of the present application, a partial space in the housing 10 near the air inlet is referred to as the air inlet space. A wind partition 16 is provided in the housing 10. The wind partition 16 divides the air inlet space into a first air inlet space 171 and a second air inlet space 172. The second heat exchanger 22 is disposed in the second air inlet space 172.

[0073] The first indoor air return opening 121 is communicated with the first air inlet space 171, and the second indoor air return opening 123 and the outdoor fresh air inlet 122 are both communicated with the second air inlet space 172.

[0074] Due to the blocking effect of the wind partition 16, the indoor air flows to the fan 30 after entering the housing 10 from the first indoor air return opening 121, rather than flowing to the second heat exchanger 22.

[0075] In some embodiments, the area of the second air inlet space 172 is larger than that of the first air inlet space 171. Since the indoor air and the outdoor fresh air both pass through the second air inlet space 172 in the return air mode and the fresh air mode with higher usage frequencies, a larger second air inlet area 172 can increase the air volume.

[0076] In some embodiments, the air duct machine includes a filter screen 40. The filter screen 40 is disposed on the windward side of the second heat exchanger 22 for filtering air.

[0077] In some embodiments, the wind partition 16 is located in the space between the air inlet and the fan 30. There is a gap between the wind partition 16 and the fan 30, forming a mixed air space. Thus, when the air duct machine operates in the mixed air mode, that is, the indoor air entering from the first indoor air return opening 121 and the outdoor fresh air flow into the housing 10 simultaneously, the indoor air and the outdoor fresh air are mixed on the windward side of the fan 30, thereby further reducing the temperature difference between the indoor air and the outdoor fresh air and avoiding the generation of condensation at the fan 30.

[0078] The fan 30 may be a structural form in which one motor drives two or more fans. This structure is applicable to the prior art and will not be elaborated herein.

[0079] The indoor air and the outdoor fresh air are driven by the same fan 30.

[0080] In some embodiments, the size of the air inlet area at the first indoor air return opening 121 can be adjusted.

[0081] The outdoor fresh air inlet 122 needs to be connected to the outside through an air duct, which may cause the static pressure on the fresh air side to be greater than or equal to the static pressure on the indoor side during actual off-site installation. To ensure that fresh air can be normally introduced even when the static pressure on the fresh air side is much greater than the static pressure on the indoor side, the air inlet area of the first indoor air return opening 121 is set to be adjustable. In this way, the appropriate size of the air return opening can be selected according to the actual off-site installation situation.

[0082] According to an embodiment of the present application, referring to Figure 2 , a plurality of knockout plates 151 stacked radially are provided inside the air outlet flange 15. By knocking off the knockout plates 151 from the inner circle to the outer circle, the air inlet area of the first indoor air return opening 121 can be changed.

[0083] Exemplarily, the knockout plate 151 has two layers, namely a first-layer knockout plate 1511 located in the inner layer and a second-layer knockout plate 1512 located in the outer layer.

[0084] When the two layers of knockout plates 151 are not knocked off, the air inlet area of the first indoor air return opening 121 is the smallest; when the first-layer knockout plate 1511 is knocked off, the air inlet area of the first indoor air return opening 121 is at an intermediate value; when the two layers of knockout plates 151 are knocked off, the air inlet area of the first indoor air return opening 121 is the largest.

[0085] In other embodiments, the size of the air inlet area of the first indoor air return opening 121 can also be adjusted by adjusting the angle of the air valve at the first indoor air return opening 121.

[0086] Corresponding to the indoor unit and the outdoor unit of the air duct machine, the refrigerant system of the air duct machine includes an outdoor part and an indoor part.

[0087] Referring to Figures 3 - 6 , in the refrigerant system of the air duct machine, the indoor part includes: a first heat exchanger 21 and a second heat exchanger 22, which perform heat exchange between indoor air and refrigerant, and between outdoor fresh air and refrigerant; an indoor expansion valve 23, which reduces the pressure of the refrigerant or is used to control the refrigerant flow rate in the first heat exchanger 21; and a solenoid valve 24, which is used to control the on / off of the flow path.

[0088] The refrigerant system further includes a liquid pipe and a gas pipe connected between the indoor part and the outdoor part.

[0089] The indoor part is respectively connected to the liquid pipe through a liquid-side stop valve 61 and to the gas pipe through a gas-side stop valve 62.

[0090] The liquid-side stop valve 61, the first heat exchanger 21, the indoor expansion valve 23, the second heat exchanger 22, and the gas-side stop valve 62 are connected in series in sequence. The first heat exchanger 21 and the indoor expansion valve 23 form a first branch, and the solenoid valve 24 is connected in parallel with the first branch.

[0091] In the refrigerant system of the air duct machine, the outdoor part includes: a compressor 51 that compresses the refrigerant; an outdoor heat exchanger 52 that performs heat exchange between outdoor air and the refrigerant; a four-way valve 53 that selectively guides the refrigerant compressed by the compressor 51 to the outdoor heat exchanger 52 or the indoor part according to the heating mode or the cooling mode; an outdoor expansion valve 54 that decompresses the refrigerant; and an outdoor fan 55 that drives outdoor air to pass through the outdoor heat exchanger 52.

[0092] When the compressor 51 is powered on, the rotation of the inner motor thereof compresses the low-pressure gaseous refrigerant to high pressure.

[0093] The four-way valve 53 guides the refrigerant compressed in the compressor 51 to the outdoor heat exchanger 52 in the cooling mode, and guides the refrigerant compressed in the compressor 51 to the indoor part in the heating mode.

[0094] The structures of the outdoor heat exchanger 52, the first heat exchanger 21, and the second heat exchanger 22 can all adopt finned heat exchangers. The finned heat exchanger may include: refrigerant pipes (not shown) through which the refrigerant flows; fins (not shown) sleeved on the refrigerant pipes to improve the heat exchange efficiency between the refrigerant and the air by increasing the surface area of the refrigerant pipes.

[0095] The outdoor expansion valve 54 decompresses the refrigerant by using a throttling action on the refrigerant.

[0096] The outdoor fan 55 can be an axial flow fan.

[0097] The working modes of the air duct machine will be introduced below in combination with the refrigerant flow path of the refrigerant system.

[0098] First, according to the different air flowing in the air duct machine, there can be a fresh air mode, a return air mode, and a mixed air mode respectively.

[0099] In the fresh air mode, only outdoor fresh air flows in the air duct machine. The air valves at the first indoor return air opening 121 and the second indoor return air opening 123 are both closed, so that the first indoor return air opening 121 and the second indoor return air opening 123 are closed; the outdoor fresh air opening 122 is opened.

[0100] In the return air mode, only indoor air flows in the air duct machine. The air valve at the outdoor fresh air opening 122 is closed, so that the outdoor fresh air opening 122 is closed; the first indoor return air opening 121 and / or the second indoor return air opening 122 is opened.

[0101] In the mixed air mode, indoor air and outdoor fresh air flow through the air duct machine simultaneously. The first indoor return air inlet 121 or / and the second indoor return air inlet 123 are opened, and the outdoor fresh air inlet 122 is opened.

[0102] Secondly, the fresh air mode includes a fresh air cooling mode, a fresh air heating mode, a fresh air dehumidification mode, etc.

[0103] The return air mode includes a return air cooling mode, a return air heating mode, a return air dehumidification mode, etc.

[0104] The mixed air mode includes a mixed air cooling mode, a mixed air heating mode, a mixed air dehumidification mode, etc.

[0105] <Fresh air cooling mode>

[0106] In some embodiments, referring to Figure 3 , the solenoid valve 24 is opened and the indoor expansion valve 23 is closed.

[0107] The compressor 51 compresses the refrigerant to high pressure. The four-way valve 53 guides the compressed refrigerant to the outdoor heat exchanger 52. The refrigerant guided to the outdoor heat exchanger 52 is condensed in the outdoor heat exchanger 52, and heat exchange between the refrigerant and the outdoor air is performed while the refrigerant is being condensed.

[0108] The outdoor expansion valve 54 reduces the pressure of the condensed refrigerant while the temperature of the refrigerant decreases.

[0109] The low-pressure and low-temperature refrigerant is supplied to the indoor side portion along the liquid pipe. Through the opened solenoid valve 24, the refrigerant flows to the second heat exchanger 22.

[0110] The second heat exchanger 22 evaporates the depressurized liquid refrigerant, and heat exchange between the refrigerant and the outdoor fresh air is performed while the refrigerant is evaporating.

[0111] As described above, in the fresh air cooling mode, the refrigerant does not flow through the first heat exchanger 21, that is, the first heat exchanger 21 does not function. The second heat exchanger 22 serves as an evaporator, and the outdoor heat exchanger 52 serves as a condenser.

[0112] Combined with Figure 7 , the solid arrows in the figure indicate the flow path of the outdoor fresh air. The outdoor fresh air inlet 122 is opened. The outdoor fresh air is cooled when passing through the second heat exchanger 22 and its temperature does not change when passing through the first heat exchanger 21, and then it is sent indoors.

[0113] In other embodiments of the fresh air cooling mode, different from the above, referring to Figure 4 , the solenoid valve 24 is closed and the indoor expansion valve 23 is fully opened.

[0114] In the indoor side portion, the refrigerant sequentially flows to the first heat exchanger 21 and the second heat exchanger 22. Both the first heat exchanger 21 and the second heat exchanger 22 evaporate the depressurized liquid refrigerant, and perform heat exchange between the refrigerant and the outdoor fresh air while the refrigerant evaporates.

[0115] As described above, in the fresh air cooling mode, the refrigerant flows through the first heat exchanger 21 and the second heat exchanger 22. The first heat exchanger 21 and the second heat exchanger 22 are used as evaporators, and the outdoor heat exchanger 52 is used as a condenser.

[0116] Combined Figure 7 , when the outdoor fresh air passes through the second heat exchanger 21, it is cooled down, and when it passes through the first heat exchanger 22, it is further cooled down, and then sent indoors.

[0117] Some other embodiments of the fresh air cooling mode are the combination of the above two embodiments: the duct machine first executes the opening of the solenoid valve 24 and the closing of the indoor expansion valve 23, and the second heat exchanger 22 cools the outdoor fresh air.

[0118] If, after the unit has been running for a period of time, the supply air temperature still differs greatly from the user-set temperature, then it changes to execute the closing of the solenoid valve 24 and the full opening of the indoor expansion valve 24, and the first heat exchanger 21 and the second heat exchanger 22 cool the outdoor fresh air.

[0119] When the first heat exchanger 21 and the second heat exchanger 22 are simultaneously used as evaporators, the volume inside the evaporator can be increased to enhance the refrigeration capacity of the unit.

[0120] If, after the unit has been running for a period of time, the difference between the supply air temperature and the user-set temperature is not large, it indicates that the refrigeration effect of the unit is relatively high. To avoid the user feeling uncomfortable due to the indoor temperature being too low and to avoid wasting energy, the system switches back to the opening of the solenoid valve 24 and the closing of the indoor expansion valve 23, and only the second heat exchanger 22 cools the outdoor fresh air.

[0121] <Fresh air heating mode>

[0122] In some embodiments, referring to Figure 5 , the solenoid valve 24 is opened and the indoor expansion valve 23 is closed.

[0123] The compressor 51 compresses the refrigerant to high pressure. The four-way valve 53 guides the compressed refrigerant to the second heat exchanger 22.

[0124] In the second heat exchanger 22, the refrigerant guided to the second heat exchanger 22 is condensed, and heat exchange between the refrigerant and the outdoor fresh air is performed while the refrigerant is being condensed.

[0125] The refrigerant continues to flow through the opened solenoid valve 24 to the outdoor expansion valve 54.

[0126] The outdoor expansion valve 54 reduces the pressure of the condensed refrigerant, and at the same time, the temperature of the refrigerant decreases.

[0127] The outdoor heat exchanger 52 evaporates the depressurized liquid refrigerant, and at the same time as the refrigerant evaporates, heat exchange is carried out between the refrigerant and the outdoor air.

[0128] As described above, in the fresh air heating mode, the refrigerant does not flow through the first heat exchanger 21, that is, the first heat exchanger 21 does not function. The second heat exchanger 22 is used as a condenser, and the outdoor heat exchanger 52 is used as an evaporator.

[0129] Combined Figure 7 , when the outdoor fresh air passes through the second heat exchanger 22, its temperature rises, and then it is sent indoors.

[0130] In some other embodiments of the fresh air cooling mode, different from the above, referring to Figure 6 , the solenoid valve 24 is closed and the indoor expansion valve 23 is fully opened.

[0131] In the indoor side part, the refrigerant sequentially flows to the second heat exchanger 22 and the first heat exchanger 21. Both the first heat exchanger 21 and the second heat exchanger 22 condense the high-temperature and high-pressure refrigerant, and at the same time as the refrigerant condenses, heat exchange is carried out between the refrigerant and the outdoor fresh air.

[0132] As described above, in the fresh air cooling mode, the refrigerant will flow through the first heat exchanger 21 and the first heat exchanger 22. The second heat exchanger 22 and the first heat exchanger 21 are used as condensers, and the outdoor heat exchanger 52 is used as an evaporator.

[0133] When the outdoor fresh air passes through the second heat exchanger 22, its temperature rises, and when it passes through the first heat exchanger 21, its temperature continues to rise, and then it is sent indoors.

[0134] Some other embodiments of the fresh air cooling mode are a combination of the above two embodiments: the air duct machine first executes the opening of the solenoid valve 24 and the closing of the indoor expansion valve 23, and the second heat exchanger 22 heats the outdoor fresh air.

[0135] If after the unit has been running for a period of time, the supply air temperature still differs greatly from the user-set temperature, then it changes to execute the closing of the solenoid valve 24 and the full opening of the indoor expansion valve 24, and the second heat exchanger 22 and the first heat exchanger 21 heat the outdoor fresh air.

[0136] When the first heat exchanger 21 and the second heat exchanger 22 are simultaneously used as condensers, the volume inside the condenser can be increased to improve the heating capacity of the unit.

[0137] If, after the unit has been operating for some time, the supply air temperature is not much different from the user-set temperature, it indicates that the unit has good heating performance. To avoid discomfort for the user due to too high indoor temperature and also to avoid energy waste, the system switches back to having solenoid valve 24 open and indoor expansion valve 23 closed, and only the second heat exchanger 22 heats the outdoor fresh air.

[0138] <Fresh air dehumidification mode>

[0139] Refer to Figure 4 , solenoid valve 24 is closed; outdoor expansion valve 54 is fully open and has no throttling effect.

[0140] Compressor 51 compresses the refrigerant to high pressure. Four-way valve 53 guides the compressed refrigerant to outdoor heat exchanger 52. The refrigerant guided to outdoor heat exchanger 52 is condensed in outdoor heat exchanger 52, and while the refrigerant is being condensed, heat exchange occurs between the refrigerant and outdoor air.

[0141] The refrigerant flows to first heat exchanger 21 after passing through fully open outdoor expansion valve 54, and first heat exchanger 21 condenses the refrigerant while performing heat exchange between the refrigerant and outdoor fresh air.

[0142] Indoor expansion valve 23 reduces the pressure of the condensed refrigerant.

[0143] Second heat exchanger 22 evaporates the depressurized liquid refrigerant, and while the refrigerant is evaporating, heat exchange occurs between the refrigerant and outdoor fresh air.

[0144] As described above, in the fresh air dehumidification mode, second heat exchanger 22 serves as an evaporator, and first heat exchanger 21 and outdoor heat exchanger 52 serve as condensers.

[0145] Combined with Figure 7 , when the outdoor fresh air flows through second heat exchanger 22, it is cooled and dehumidified, and then when it passes through first heat exchanger 21, it is heated and warmed up, achieving dehumidification without cooling.

[0146] <Return air cooling mode>

[0147] The refrigerant flow path is the same as that in the fresh air cooling mode and will not be elaborated here.

[0148] Refer to Figure 8 , in the return air cooling mode, first indoor air return opening 121 and outdoor fresh air opening 122 are closed, and second indoor air return opening 123 is open. Indoor air enters the housing 10 from second indoor air return opening 123, is cooled by second heat exchanger 22 and then sent indoors, or is cooled by first heat exchanger 21 and second heat exchanger 22 and then sent indoors.

[0149] <Return air heating mode>

[0150] The refrigerant flow path is the same as that in the fresh air heating mode, which will not be elaborated here.

[0151] Refer to Figure 8 , in the return air heating mode, the first indoor return air inlet 121 and the outdoor fresh air inlet 122 are closed, and the second indoor return air inlet 123 is opened. Indoor air enters the housing 10 through the second indoor return air inlet 123, is heated by the second heat exchanger 22 and then sent to the room, or is heated by the first heat exchanger 21 and the second heat exchanger 22 and then sent to the room.

[0152] <Return air dehumidification mode>

[0153] The refrigerant flow path is the same as that in the fresh air dehumidification mode, which will not be elaborated here. The first heat exchanger 21 is used as a condenser, and the second heat exchanger 22 is used as an evaporator.

[0154] Refer to Figure 8 , in the return air dehumidification mode, the first indoor return air inlet 121 and the outdoor fresh air inlet 122 are closed, and the second indoor return air inlet 123 is opened. Indoor air enters the housing 10 through the second indoor return air inlet 123, is cooled and dehumidified by the second heat exchanger 22, and then is heated by the first heat exchanger 21 and sent to the room.

[0155] <Mixed air cooling mode>

[0156] In the mixed air cooling mode, generally, the outdoor fresh air temperature is higher than the indoor return air temperature. When the dew point temperature corresponding to the outdoor fresh air temperature is higher than the indoor return air temperature, condensation will occur in the unit. Therefore, in the mixed air cooling mode of this application, the second heat exchanger 22 is required to cool the introduced outdoor fresh air first.

[0157] Refer to Figure 4 , the solenoid valve 24 is closed; the indoor expansion valve 23 is fully opened and does not play a throttling role.

[0158] The compressor 51 compresses the refrigerant to high pressure. The four-way valve 53 guides the compressed refrigerant to the outdoor heat exchanger 52. The refrigerant guided to the outdoor heat exchanger 52 is condensed in the outdoor heat exchanger 52, and heat exchange between the refrigerant and the outdoor air is performed while the refrigerant is being condensed.

[0159] The outdoor expansion valve 54 reduces the pressure of the condensed refrigerant, and at the same time the refrigerant temperature decreases.

[0160] The low-pressure and low-temperature refrigerant is supplied to the first heat exchanger 21 on the indoor side along the liquid pipe.

[0161] The first heat exchanger 21 evaporates the decompressed liquid refrigerant, and heat exchange between the refrigerant and the mixed air is performed while the refrigerant is evaporating.

[0162] The refrigerant continues to flow through the fully open indoor expansion valve 23 to the second heat exchanger 22. The second heat exchanger 22 evaporates the depressurized liquid refrigerant and performs heat exchange between the refrigerant and the outdoor fresh air while the refrigerant evaporates.

[0163] As described above, in the mixed-air refrigeration mode, the first heat exchanger 21 and the second heat exchanger 22 are used as evaporators, and the outdoor heat exchanger 52 is used as a condenser.

[0164] Refer to Figure 9 , in the mixed-air refrigeration mode, the first indoor return air inlet 121 and the outdoor fresh air inlet 122 are opened, and the second indoor return air inlet 123 is closed.

[0165] The outdoor fresh air is first cooled by the second heat exchanger 22 and then mixed with the indoor return air. The mixed air is further cooled by the first heat exchanger 21 and then sent to the room. This can not only improve the refrigeration capacity of the unit and avoid the problem of increased load caused by the introduction of fresh air, but also effectively solve the problem of condensation of the unit.

[0166] <Mixed-air heating mode>

[0167] Under normal circumstances, the temperature of the outdoor fresh air is lower than the temperature of the indoor return air. When the outdoor fresh air with too low temperature is introduced, the temperature of the outdoor fresh air is lower than the dew point temperature corresponding to the indoor working condition, which will cause the condensation phenomenon of the unit. Therefore, in the mixed-air heating mode of the present application, it is necessary for the second heat exchanger 22 to first heat up the introduced outdoor fresh air.

[0168] Refer to Figure 6 , the solenoid valve 24 is closed; the indoor expansion valve 23 is fully open and does not play a throttling role.

[0169] The compressor 51 compresses the refrigerant to high pressure. The four-way valve 53 guides the compressed refrigerant to the second heat exchanger 22.

[0170] In the second heat exchanger 22, the refrigerant guided to the second heat exchanger 22 is condensed, and heat exchange between the refrigerant and the outdoor fresh air is performed while the refrigerant is condensed.

[0171] Then the refrigerant flows through the fully open indoor expansion valve 23 to the first heat exchanger 21. The first heat exchanger 21 performs heat exchange between the refrigerant and the mixed air while the refrigerant is condensed.

[0172] The refrigerant continues to flow to the outdoor expansion valve 54. The outdoor expansion valve 54 decompresses the condensed refrigerant, and at the same time the temperature of the refrigerant decreases.

[0173] The outdoor heat exchanger 52 evaporates the depressurized liquid refrigerant and performs heat exchange between the refrigerant and the outdoor air while the refrigerant evaporates.

[0174] As described above, in the mixed-air heating mode, the outdoor heat exchanger 52 functions as an evaporator, and the first heat exchanger 21 and the second heat exchanger 22 function as condensers.

[0175] Referring to Figure 9 , in the mixed-air cooling mode, the first indoor return air inlet 121 and the outdoor fresh air inlet 122 are opened, and the second indoor return air inlet 123 is closed.

[0176] The outdoor fresh air is first heated by the second heat exchanger 22 and then mixed with the indoor return air. The mixed air is further heated by the first heat exchanger 21 and then sent to the room. This can not only increase the volume inside the condenser, improve the heating capacity of the unit, and avoid the problem of increased load caused by introducing fresh air, but also effectively solve the problem of unit condensation.

[0177] <Mixed-air dehumidification mode>

[0178] Referring to Figure 4 , the solenoid valve 24 is closed; the outdoor expansion valve 54 is fully opened and does not play a throttling role.

[0179] The refrigerant flow path is the same as that in the fresh-air dehumidification mode and will not be elaborated here. The first heat exchanger 21 functions as a condenser, and the second heat exchanger 22 functions as an evaporator.

[0180] Referring to Figure 9 , in the mixed-air dehumidification mode, the first indoor return air inlet 121 is closed, and the outdoor fresh air inlet 122 and the second indoor return air inlet 123 are opened.

[0181] The mixed air of the outdoor fresh air and the indoor air is cooled and dehumidified by the second heat exchanger 22, and then heated by the first heat exchanger 21 to achieve dehumidification without cooling.

[0182] In some embodiments, during the heating operation of the air duct unit, frost may form on the outdoor heat exchanger 52, and the unit needs to perform defrosting operation.

[0183] <Defrosting operation>

[0184] Referring to Figure 4 , the solenoid valve 24 is closed; the outdoor expansion valve 54 is fully opened and does not play a throttling role.

[0185] The compressor 51 compresses the refrigerant to high pressure. The four-way valve 53 guides the compressed refrigerant to the outdoor heat exchanger 52. The refrigerant guided to the outdoor heat exchanger 52 is condensed in the outdoor heat exchanger 52.

[0186] After passing through the fully opened outdoor expansion valve 54, the refrigerant flows to the first heat exchanger 21. The first heat exchanger 21 condenses the refrigerant and performs heat exchange between the refrigerant and the indoor air while condensing the refrigerant.

[0187] The indoor expansion valve 23 reduces the pressure of the condensed refrigerant, and at the same time, the temperature of the refrigerant decreases.

[0188] The second heat exchanger 22 evaporates the depressurized liquid refrigerant, and at the same time as the refrigerant evaporates, heat exchange is performed between the refrigerant and the indoor air.

[0189] As described above, during the defrost operation, the outdoor heat exchanger 52 and the first heat exchanger 21 are used as condensers. The second heat exchanger 22 is used as an evaporator.

[0190] Since the high-temperature gaseous refrigerant compressed by the compressor 51 flows through the outdoor heat exchanger 52, the frost layer on the outdoor heat exchanger 52 can be effectively removed.

[0191] Refer to Figure 10 , the dotted arrows in the figure indicate the flow path of the indoor air. During the defrost operation, the first indoor air return opening 121 is opened, and the outdoor fresh air opening 122 and the second indoor air return opening 123 are closed; the fan 30 operates, so that the indoor air enters the housing 10 through the first indoor air return opening 121, then is heated when passing through the first heat exchanger 21, and then sent to the room.

[0192] In the embodiment of the present application, when the unit is in the defrost operation, the actual air supply will be heated by the first heat exchanger 21 and then sent to the room, greatly improving the user's comfort experience. At the same time, the fan 30 does not need to be turned off during the defrost operation, which can effectively ensure the reliability of the unit operation.

[0193] As described above, according to the air duct machine of the embodiment of the present application, by providing an outdoor fresh air opening 122 communicating with the outdoor air on the air duct machine, outdoor fresh air can be introduced into the room; by providing a second heat exchanger 22 on the air inlet side of the outdoor fresh air, thus, the outdoor fresh air can be preheated or precooled by the second heat exchanger 22, avoiding the condensation problem caused by the large temperature difference between the outdoor fresh air and the indoor air when the unit introduces fresh air.

[0194] In addition, a solenoid valve 24 is connected in parallel to the first branch in which the second heat exchanger 22 and the indoor expansion valve 23 are connected in series. When introducing fresh air, whether the second heat exchanger 22 functions can be realized by the opening and closing states of the indoor expansion valve 23 and the solenoid valve 24. Thus, when the difference between the air supply temperature and the set temperature is small, it is selected that the first heat exchanger 21 does not function to avoid energy waste and the problem of poor user experience caused by too low / high indoor temperature; when the difference between the air supply temperature and the set temperature is large, it is selected that the first heat exchanger 21 functions to improve the refrigeration / heating capacity of the unit.

[0195] In addition, two indoor air return vents are provided on the air duct unit. The indoor air introduced by the first indoor air return vent 121 only passes through the first heat exchanger 21 in the housing 10, and the indoor air introduced by the second indoor air return vent 123 passes through the first heat exchanger 21 and the second heat exchanger 22 in sequence in the housing 10. Thus, in the air return mode, the indoor air is introduced by the second indoor air return vent 123. Combined with the refrigerant system, energy can be saved when the indoor air only passes through the second heat exchanger 22 for temperature adjustment. When the indoor air passes through the second heat exchanger 22 and the first heat exchanger 21 for temperature adjustment respectively, the temperature adjustment capacity of the unit can be improved; in the mixed air cooling / heating mode, the indoor air is introduced by the first indoor air return vent 121, and the outdoor fresh air is mixed with the indoor air after passing through the second heat exchanger 22, which can reduce the temperature difference between the two and avoid the condensation problem.

[0196] In addition, a solenoid valve 24 is provided in the refrigerant system. The on / off states of the outdoor expansion valve 54 and the solenoid valve 24 can be used to realize that when the unit operates for dehumidification, the second heat exchanger 22 is used for cooling and dehumidifying, and the first heat exchanger 21 is used for heating up, so as to realize dehumidification without cooling.

[0197] In addition, a solenoid valve 24 is provided in the refrigerant system. The on / off states of the outdoor expansion valve 54 and the solenoid valve 24 can be used to realize that when the unit operates for fresh air defrosting, the first heat exchanger 21 is used as a condenser, and the indoor air is heated by the first heat exchanger 21, improving the comfort of users; the fan 30 of the air duct unit does not need to be turned off, which can effectively ensure the reliability of the unit operation.

[0198] In addition, the mixed air space of the outdoor fresh air and the indoor air in the air duct unit is located between the second heat exchanger 22 and the first heat exchanger 21, so that the outdoor fresh air is preheated / precooled by the second heat exchanger 22 and then mixed with the indoor air, avoiding the generation of condensation inside the unit.

[0199] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

[0200] For the sake of convenience in explanation, the above description has been made in combination with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. According to the above teachings, various modifications and variations can be obtained. The selection and description of the above embodiments are for better explaining the principles and actual applications, so that those skilled in the art can better use the embodiments and various different modified embodiments suitable for specific usage considerations.

Claims

1. A duct machine, characterized in that: include: A housing, on which an air inlet and an air supply outlet are provided, wherein the air inlet includes a first indoor return air outlet, a second indoor return air outlet and an outdoor fresh air outlet, the first indoor return air outlet is connected with the air supply outlet to form a first flow path, and the outdoor fresh air outlet is connected with the air supply outlet to form a second flow path; indoor air entering from the second indoor return air outlet moves along the second flow path in the housing; A first heat exchanger is disposed in the housing corresponding to the air supply port, and the first heat exchanger is located on the first flow path and the second flow path; A second heat exchanger is provided corresponding to the outdoor fresh air outlet and the second indoor return air outlet, and the second heat exchanger is located on the second flow path; The duct unit also includes an indoor expansion valve and a solenoid valve; in the refrigerant system of the duct unit, the liquid side stop valve, the first heat exchanger, the indoor expansion valve, the second heat exchanger, and the gas side stop valve are connected in series in sequence; the first heat exchanger and the indoor expansion valve form a first branch, and the solenoid valve is connected in parallel with the first branch.

2. The air duct machine according to claim 1, characterized in that: Part of the space in the shell near the air inlet is the air inlet space; The air duct machine also includes: A fan, disposed between the air inlet space and the first heat exchanger, for driving the flow of indoor air and outdoor fresh air; A wind baffle is provided in the shell, and the wind baffle divides the air inlet space into a first air inlet space connected to the first indoor return air outlet, and a second air inlet space connected to the outdoor fresh air outlet and the second indoor return air outlet; the second heat exchanger is arranged in the second air inlet space.

3. The air duct machine according to claim 2, characterized in that: There is a gap between the wind baffle and the fan to form a mixed air space for outdoor fresh air and indoor air.

4. The air duct machine according to claim 2, characterized in that: An area of ​​the second air inlet space is greater than an area of ​​the first air inlet space.

5. The air duct machine according to claim 1, characterized in that: An air outlet flange is provided at the first indoor return air outlet, and a plurality of knock-off plates are stacked in the air outlet flange along the radial direction.

6. The air duct machine according to claim 1, characterized in that: The first indoor return air outlet, the outdoor fresh air outlet, and the second indoor return air outlet are located on the same side wall of the shell.

7. The air duct machine according to any one of claims 1 to 6, characterized in that: In the refrigerant system, an outdoor expansion valve is connected in series between the outdoor heat exchanger and the liquid-side stop valve; During defrosting operation, the outdoor expansion valve is in a fully open state, the solenoid valve is in a closed state, the outdoor heat exchanger and the first heat exchanger are used as condensers, and the second heat exchanger is used as an evaporator; The first indoor return air vent is in an open state, and the outdoor fresh air vent and the second indoor return air vent are in a closed state; the air duct unit allows indoor air to be blown into the room through the first indoor return air vent and the first heat exchanger.

8. The air duct machine according to any one of claims 1 to 6, characterized in that: In dehumidification mode, the outdoor heat exchanger and the first heat exchanger in the refrigerant system are used as condensers, and the second heat exchanger is used as an evaporator; The first indoor return air vent is in a closed state, and the second indoor return air vent is in an open state during indoor dehumidification.

9. The air duct machine according to any one of claims 1 to 6, characterized in that: In the mixed air mode, the first indoor return air vent and the outdoor fresh air vent are in an open state, and the second indoor return air vent is in a closed state.

10. A duct machine, characterized in that: include: A housing having an air inlet and an air supply outlet, wherein the air inlet includes a first indoor return air inlet and an outdoor fresh air inlet, the first indoor return air inlet is connected to the air supply outlet to form a first flow path, and the outdoor fresh air inlet is connected to the air supply outlet to form a second flow path; A first heat exchanger is disposed in the housing corresponding to the air supply port, and the first heat exchanger is located on the first flow path and the second flow path; A second heat exchanger is arranged corresponding to the outdoor fresh air outlet, and the second heat exchanger is located on the second flow path; Wherein, the shell is further provided with a second indoor return air port, and the indoor air entering through the second indoor return air port moves along the second flow path in the shell; When the air duct unit introduces fresh air, the second heat exchanger can be used as an evaporator during cooling and as a condenser during heating.

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