Air duct assembly, indoor unit and heating and ventilation system

Abstract

The invention discloses an air duct assembly, an indoor unit and a heating and ventilation system.The air duct machine comprises a first shell and a second shell, the first shell and the second shell are matched to define a draught fan cavity and a diffusion cavity which communicate with each other, a draught fan is arranged in the draught fan cavity, a volute tongue is arranged at the joint of the draught fan cavity and the diffusion cavity, and the draught fan drives external airflow to enter the draught fan cavity; the volute tongue guides at least part of airflow to enter the diffusion cavity from the fan cavity; the second shell comprises a backflow channel, a first surface forming the cavity bottom face of the diffusion cavity and a second surface forming part of the cavity wall face of the fan cavity, a first opening is formed in the first surface, a second opening is formed in the second surface, and the backflow channel extends to the second opening from the first opening. According to the technical scheme, air supply and pressurization can be conducted on the side, close to the volute tongue, of the fan, so that vortexes caused by pressure difference are weakened, and the pneumatic performance in the air duct assembly is improved.

Description

Technical Field

[0001] This application relates to the technical field of air conditioners, and particularly to an air duct assembly, an indoor unit, and a heating, ventilation, and air conditioning (HVAC) system. Background Art

[0002] The indoor unit of an existing HVAC system includes an air duct assembly. The air duct assembly includes a blower chamber and a diffuser chamber that are connected and communicate with each other. A blower is provided in the blower chamber, and the diffuser chamber is used to receive the air flow blown from the blower chamber and perform diffusion to increase the pressure and flow rate of the air flow, so as to improve the refrigeration or heating effect.

[0003] In the related art, a scroll tongue is also provided in the air duct assembly at the transition between the blower chamber and the diffuser chamber. The scroll tongue is used to split the air flow of the blower to guide part of the air flow to the diffuser chamber and make part of the air flow flow back to the air inlet side of the blower, resulting in a pressure difference between the side of the blower close to the scroll tongue and the side of the blower far from the scroll tongue, thereby generating an eddy current. This eddy current will affect the operating efficiency of the blower and cause poor overall gas flow performance in the air duct assembly. Summary of the Invention

[0004] Embodiments of this application provide an air duct assembly, an indoor unit, and an HVAC system, which can supplement air and increase pressure at the side of the blower close to the scroll tongue to weaken the eddy current caused by the pressure difference and improve the aerodynamic performance in the air duct assembly.

[0005] In a first aspect, embodiments of this application provide an air duct assembly, including:

[0006] A first housing; and

[0007] A second housing, the first housing and the second housing cooperate to define a blower chamber and a diffuser chamber that are connected and communicate with each other. A blower is provided in the blower chamber, and a scroll tongue is provided at the transition between the blower chamber and the diffuser chamber. The blower drives external air flow into the blower chamber, and the scroll tongue guides at least part of the air flow from the blower chamber into the diffuser chamber;

[0008] The second housing includes a return passage, a first surface that forms the bottom surface of the diffuser chamber, and a second surface that forms part of the chamber wall surface of the blower chamber. A first opening is provided on the first surface, a second opening is provided on the second surface, and the return passage extends from the first opening to the second opening.

[0009] In some embodiments, the return passage is curved.

[0010] In some embodiments, the width of the return passage remains unchanged or gradually expands in the direction from the first opening to the second opening.

[0011] In some of these embodiments, the return air channel has its extension line in the direction of the second opening passing through the blower, and the included angle between the extension line and the outer peripheral tangent of the blower is θ, where θ is less than or equal to 15 degrees and greater than or equal to 0 degrees;

[0012] Alternatively, the return air channel has its extension line in the direction of the second opening passing through from the outside of the blower, and the included angle between the extension line and the outer peripheral tangent of the blower is β, where β is less than or equal to 45 degrees and greater than or equal to 0 degrees.

[0013] In some of these embodiments, θ is equal to 0 degrees or β is equal to 0 degrees, so that the extension line of the return air channel in the direction of the second opening coincides with the outer peripheral tangent of the blower.

[0014] In some of these embodiments, the second housing further includes a connecting surface connected between the first surface and the second surface. The connecting surface is recessed to form an air flow groove. One end of the air flow groove penetrates through the first surface to communicate with the first opening, and the other end of the air flow groove penetrates through the second surface to communicate with the second opening. The volute tongue covers the connecting surface so that the air flow groove forms the return air channel.

[0015] In some of these embodiments, the second housing includes:

[0016] A diffuser chamber lower shell, which is provided with the first surface and is connected to the volute tongue;

[0017] A support member, which is connected to the side of the diffuser chamber lower shell facing away from the first surface and is connected to the volute tongue. The side of the support member facing away from the volute tongue is configured as a first return air surface; and

[0018] A deflector, which is connected to the side of the diffuser chamber lower shell facing away from the first surface and is spaced from the support member. The side of the deflector facing the support member is configured as a second return air surface. The second return air surface and the first return air surface cooperate to form the return air channel, and the deflector and the support member cooperate to form the second opening.

[0019] In some of these embodiments, at least one flow guiding rib is provided on one of the first return air surface and the second return air surface, and the other of the first return air surface and the second return air surface abuts against the at least one flow guiding rib.

[0020] In some of these embodiments, the flow guiding rib protrudes from the first return air surface and is integrally formed with the first return air surface, and the second return air surface abuts against the flow guiding rib; and / or,

[0021] The guiding rib protrudes from the second air return surface and is integrally formed with the second air return surface, and the first air return surface abuts against the guiding rib.

[0022] In some embodiments, a plurality of the guiding ribs are provided on one of the first air return surface and the second air return surface. The plurality of guiding ribs are arranged side by side and spaced apart in the transverse direction of the return channel. The plurality of guiding ribs divide the first opening into a plurality of sub-inlets. The transverse direction of the return channel is perpendicular to the direction of air flow in the return channel and perpendicular to the direction of the first air return surface facing the second air return surface.

[0023] In some embodiments, the air duct assembly further includes a plurality of clamping blocks. Each clamping block protrudes from the guiding rib located on the first air return surface and is integrally formed with the guiding rib; a plurality of clamping openings are formed in the second air return surface, and each clamping block is inserted into one of the clamping openings.

[0024] In some embodiments, the guiding rib extends along the longitudinal direction of the return channel and from the first opening toward the side where the second opening is located. The longitudinal direction of the return channel is the direction of air flow in the return channel;

[0025] A plurality of the guiding ribs are provided on one of the first air return surface and the second air return surface. The plurality of guiding ribs are arranged side by side and spaced apart in the transverse direction of the return channel. The transverse direction of the return channel is perpendicular to the direction of air flow in the return channel and perpendicular to the direction of the first air return surface facing the second air return surface.

[0026] In some embodiments, in the transverse direction of the return channel, the distance between adjacent two guiding ribs is equal.

[0027] In some embodiments, in the transverse direction of the return channel, the return channel includes a plurality of air return areas arranged side by side. The air pressure of adjacent two air return areas is different. The distance between adjacent two guiding ribs in the air return area with a larger air pressure is a1, and the distance between adjacent two guiding ribs in the air return area with a smaller air pressure is a2, and a2 > a1.

[0028] In some embodiments, at least one of the guiding ribs provided on one of the first air return surface and the second air return surface has two third surfaces arranged oppositely. The parts of the two third surfaces facing the same side protrude perpendicularly or obtusely from one of the first air return surface and the second air return surface.

[0029] In some of these embodiments, the flow guide rib has a fourth surface connected between two of the third surfaces, and the fourth surface abuts against the other of the first air return surface and the second air return surface.

[0030] In some of these embodiments, in the direction from the first opening of the return channel towards the second opening, the vertical distance between the two third surfaces gradually decreases or remains unchanged.

[0031] In some of these embodiments, the diffuser chamber lower shell and the support member are of an integral structure.

[0032] In some of these embodiments, the diffuser chamber lower shell and the flow guide member are of an integral structure.

[0033] In some of these embodiments, the flow guide member includes a connecting portion, a flow guiding portion, and a chamber wall portion. The connecting portion is laminated on a side of the diffuser chamber lower shell facing away from the first surface and is detachably mounted on the diffuser chamber lower shell. The flow guiding portion is connected to the connecting portion at an angle, and the flow guiding portion and the support member cooperate to form the return channel and the second opening. The chamber wall portion is connected to an end of the flow guiding portion facing away from the connecting portion at an angle and extends in a direction away from the diffuser chamber lower shell.

[0034] In some of these embodiments, the connecting portion has a first connecting hole, and the diffuser chamber lower shell has a second connecting hole corresponding to the first connecting hole. The air duct assembly further includes:

[0035] A fastener that sequentially passes through the second connecting hole and the first connecting hole to fix the connecting portion to the diffuser chamber lower shell.

[0036] In some of these embodiments, the air duct assembly further includes a grille, which is detachably connected to the chamber wall portion and covers the air inlet side of the blower chamber.

[0037] In some of these embodiments, one of a fixing buckle and a fixing slot is provided at an end of the chamber wall portion facing away from the flow guiding portion, and the other of the fixing buckle and the fixing slot is provided on the grille. The fixing buckle and the fixing slot are snap-fitted.

[0038] In a second aspect, an embodiment of the present application provides an indoor unit, which includes the air duct assembly as described above.

[0039] In some of these embodiments, the indoor unit is a duct machine, and the blower is a cross-flow blower.

[0040] In a third aspect, an embodiment of the present application provides a heating, ventilation, and air conditioning (HVAC) system, which includes an outdoor unit and the indoor unit as described above. The indoor unit and the outdoor unit form a refrigerant cycle.

[0041] Based on the air duct assembly, indoor unit, and heating, ventilation, and air conditioning (HVAC) system according to the embodiments of the present application, a first opening is provided on the first surface of the bottom surface of the diffuser cavity formed by the second housing, and a second opening is provided on the second surface of a partial cavity wall surface forming the fan cavity. At the same time, a return channel is provided at the second housing, and the return channel extends from the first opening to the second opening.

[0042] In this way, the airflow driven by the fan is split by the volute tongue to flow to the diffuser cavity and the side of the volute tongue near the air inlet side of the fan respectively. After splitting, the pressure of the airflow flowing into the diffuser cavity increases, so that the airflow pressure at the first opening is greater than the airflow pressure at the second opening. Furthermore, due to the pressure difference between the first opening and the second opening, part of the airflow entering the diffuser cavity actively flows back to the air inlet side of the volute tongue near the fan through the return channel to do work again. It can not only make up for the pressure on the side of the fan near the volute tongue, thereby weakening the eddy current caused by the pressure difference, effectively improving the operating efficiency of the fan, improving the air intake efficiency and anti-pressure performance of the air inlet side of the fan, thus enhancing the overall aerodynamic performance of the air duct assembly. At the same time, after weakening the eddy current, the aerodynamic noise in the air duct assembly can be synchronously reduced to enhance the user experience. And because the airflow pressure at the diffuser cavity is greater than the airflow pressure of the volute tongue, compared with the solution of setting the first opening at the volute tongue, the pressure difference between the first opening and the second opening of the present application will also be greater than the solution of setting the first opening at the volute tongue. Furthermore, the efficiency of the airflow passing through the return channel can be further improved to enhance the effect of air supplement and pressure boost. Description of the Drawings

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0044] Figure 1 It is a schematic structural diagram of an embodiment of the air duct machine of the present application;

[0045] Figure 2 It is Figure 1 the exploded structural diagram of the shown air duct machine;

[0046] Figure 3 It is a schematic structural diagram of another perspective of the air duct machine of the present application;

[0047] Figure 4 It is Figure 3 the cross-sectional view at A-A shown;

[0048] Figure 5 It isFigure 4 Partial enlarged view at position A;

[0049] Figure 6 Cross-sectional view of the air duct assembly of the air duct machine of the present application;

[0050] Figure 7 Structural schematic diagram of the first housing of the air duct machine of the present application after disassembly;

[0051] Figure 8 is Figure 7 Partial enlarged view at position B;

[0052] Figure 9 Structural schematic diagram of the second housing of the air duct assembly of the present application;

[0053] Figure 10 is Figure 9 Partial enlarged view at position N;

[0054] Figure 11 Structural schematic diagram of the flow guide member of the air duct assembly of the present application.

[0055] Explanation of the reference numerals in the drawings:

[0056] 1. Indoor unit; 10. Air duct assembly; 11. Fan chamber; 12. Diffuser chamber; 13. Heat exchange chamber; 14. Air inlet; 15. Air outlet; 20. First housing; 21. Upper shell of the fan chamber; 22. Upper shell of the diffuser chamber; 23. Upper shell of the heat exchange chamber; 24. Front shell of the fan chamber; 30. Second housing; 50. Lower shell of the diffuser chamber; 60. Water receiving tray; 31. Return channel; 32. First opening; 33. Second opening; 34. First surface; 35. Second surface; 37. Support member; 371. First return air surface; 38. Flow guide member; 381. Connection part; 382. Flow guide part; 3821. Second return air surface; 3822. Card slot opening; 383. Chamber wall part; 3831. Fixed card slot; 39. Flow guide rib; 391. Third surface; 392. Fourth surface; 393. Block; 40. Volute tongue; 70. Side wall panel; 80. Insulation layer; 91. Fan; 92. Heat exchanger; 93. Electric control box assembly; 98. Grille.

[0057] The realization of the purpose, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0058] To make the purpose, technical solutions and advantages of the present application clearer, the following will further describe the embodiments of the present application in detail with reference to the accompanying drawings.

[0059] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. On the contrary, they are merely examples of devices and methods that are consistent with some aspects of the present application as detailed in the appended claims.

[0060] In the description of the present application, it should be understood that the terms "first", "second", etc. are used only for descriptive purposes and cannot be construed as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances. In addition, in the description of the present application, unless otherwise specified, "a plurality of" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art belonging to the technical field of the present application. The terms used in the description of this specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0062] The indoor unit of the existing HVAC system includes a duct assembly, and the duct assembly includes a blower chamber and a diffuser chamber that are connected and communicate with each other. A blower is provided in the blower chamber, and the diffuser chamber is used to receive the airflow blown from the blower chamber and perform diffusion to increase the pressure and flow rate of the airflow, so as to improve the refrigeration or heating effect.

[0063] In the related art, a volute tongue is also provided in the duct assembly at the junction of the blower chamber and the diffuser chamber. The volute tongue is used to split the airflow of the blower to guide part of the airflow to the diffuser chamber and make part of the airflow flow back to the air inlet side of the blower, resulting in a pressure difference between the side of the blower close to the volute tongue and the side of the blower far from the volute tongue, thereby generating a vortex. This vortex will affect the operating efficiency of the blower and result in poor overall gas flow performance in the duct assembly.

[0064] To solve the above problems, one aspect of the present application proposes a heating, ventilation, and air conditioning (HVAC) system. In the embodiments of the present application, the HVAC system includes, but is not limited to, devices such as air conditioners, multi-split systems, and heat pumps, and can be applied to large-scale places such as shopping malls and office buildings. Among them, the HVAC system can include an indoor unit, an outdoor unit, and a connecting pipe. The indoor unit 1 is connected to the outdoor unit through the connecting pipe so that the indoor unit and the outdoor unit form a refrigerant cycle. In some actual use scenarios, the indoor unit of the present application can be installed indoors. The outdoor unit is responsible for refrigeration or heating and transports the refrigerant through the connecting pipe. The refrigerant exchanges heat with the indoor air and the outdoor air respectively. The indoor unit is responsible for delivering cold air or hot air indoors to achieve the effect of cooling or heating.

[0065] Referring to Figures 1 to 3 , specifically, the indoor unit 1 can include, but is not limited to, structural forms such as duct air conditioners, wall-mounted air conditioner indoor units, and floor-standing air conditioner indoor units, etc. Among them, duct air conditioners are usually installed on the ceiling by ceiling suspension and can be hidden inside the ceiling, so that the duct air conditioner has a better hiding effect and is more beautiful compared to other structural forms of the indoor unit 1. In addition, the duct air conditioner adopts decentralized air supply, and the air supply effect is more comfortable. The indoor unit 1 can include an air duct assembly 10, a fan 91, a heat exchanger 92, and an electric control box assembly 93.

[0066] With reference to Figure 2 , Figure 4 and Figure 5 , a fan chamber 11, a diffuser chamber 12, and a heat exchange chamber 13 are sequentially formed in the air duct assembly 10 and communicate with each other. The air duct assembly 10 also forms an air inlet 14 communicating with the fan chamber 11 and an air outlet 15 communicating with the heat exchange chamber 13. Among them, the fan chamber 11 is configured to accommodate the fan 91. The diffuser chamber 12 is used to receive the air flow blown from the fan chamber 11 and perform diffusion to increase the pressure and flow rate of the air flow, so as to improve the refrigeration or heating effect. The heat exchange chamber 13 is configured to accommodate the heat exchanger 92. In this way, the external air flow can flow in from the air inlet 14 under the action of the fan 91, and sequentially flow through the fan chamber 11, the diffuser chamber 12, and the heat exchange chamber 13, and then heat or cool the external air flow through the heat exchanger 92 in the heat exchange chamber 13 and flow out from the air outlet 15.

[0067] The air duct assembly 10 includes a first housing 20 and a second housing 30. The first housing 20 and the second housing 30 cooperate to define a communicating diffuser chamber 12, a blower chamber 11, and a heat exchange chamber 13. The first housing 20 and the second housing 30 can be alloys or metals such as aluminum or steel to meet requirements such as structural strength and long service life. Of course, the first housing 20 and the second housing 30 can also be made of plastic to meet requirements such as lighter weight, and the present application does not limit this. Of course, it can also be a combination in which one of the first housing 20 and the second housing 30 is made of alloy or metal, and the other is made of plastic. Further, the air duct assembly 10 further includes two side enclosures 70. The two side enclosures 70 can be connected to the first housing 20 and the second housing 30 by means such as snap connection or screw connection to fix the first housing 20 and the second housing 30, and the two side enclosures 70 are disposed opposite to each other. In this way, the first housing 20, the second housing 30, and the two side enclosures 70 cooperate to configure the outline of the entire air duct assembly 10. And the air inlet 14 can be formed by enclosing the first housing 20, the second housing 30, and the side enclosures 70, and the air outlet 15 is formed by the cooperation of the first housing 20 and the second housing 30.

[0068] It should be noted that the first housing 20, the second housing 30, and the side enclosures 70 can act as an outer shell. In this way, there is no need to additionally provide other outer shell structures, reducing the number of components of the air duct assembly 10 and reducing the volume of the air duct assembly 10, realizing the miniaturization of the air duct machine 1 to adapt to more use environments with relatively compact installation spaces. Of course, in other embodiments, the indoor unit 1 can further include an outer shell, and the outer shell can be configured to cover the outer surfaces of the first housing 20, the second housing 30, and the side enclosures 70, only exposing the air outlet 15 and the air inlet 14 to communicate with the outside, so as to protect the first housing 20, the second housing 30, and the side enclosures 70.

[0069] The electronic control box assembly 93 can be installed on the surface of the air duct assembly 10 for installation and fixation. The electronic control box assembly 93 can be electrically connected to the blower 91 and the heat exchanger 92 respectively to control or adjust the blower 91 and the heat exchanger 92. For example, when the temperature in the environment where the air duct machine 1 is located reaches the set value, the electronic control box assembly 93 can send an instruction to turn off the blower 91 and the heat exchanger 92 to reduce energy consumption and prevent the indoor temperature from being too low or too high.

[0070] Furthermore, the electronic control box assembly 93 can be installed on the surface of the diffuser chamber lower housing 50 facing away from the diffuser chamber 12, adjacent to and facing the air suction port 14. In this way, maintenance personnel can directly disassemble and assemble the electronic control box assembly 93 at a position adjacent to the air suction port 14. Since there is no other structure blocking the area adjacent to the air suction port 14, the operation is more convenient when maintenance personnel disassemble and assemble the electronic control box assembly 93.

[0071] The blower 91 can be arranged in a cylindrical long strip shape. The blower 91 can be a cross-flow impeller, a centrifugal blower, an axial-flow blower, etc. When the blower 91 is configured as a cross-flow impeller, the cross-flow impeller has the advantages of small radial dimension, low rotational speed, low noise, uniform air outlet, etc. Its axial length can be arbitrarily extended without affecting the gas flow state, etc. Moreover, compared with a centrifugal blower or an axial-flow blower, the cost of the cross-flow impeller is lower. And the blower 91 can be arranged directly opposite to the air suction port 14 so that the outside air flow can flow towards the blower 91 along a shorter path through the air suction port 14, reducing the loss during the flow process.

[0072] The heat exchanger 92 is housed in the heat exchange chamber 13 and is connected to the air conditioner outdoor unit through a connecting pipe, so that the refrigerant can circulate between the air conditioner outdoor unit and the air conditioner indoor unit 1. When the hot air flows towards the heat exchange chamber 13 and passes through the heat exchanger 92, the hot air will exchange heat with the refrigerant of the heat exchanger 92, enabling the refrigerant to absorb heat. In this way, the heat can be transferred to the refrigerant to achieve the refrigeration effect. The heat exchanger 92 can be generally in a V shape, so as to increase the heat exchange area and improve the heat exchange efficiency. And the heat exchanger 92 and the air discharge port 15 can be arranged directly opposite to each other. In this way, the air flow can flow towards the air discharge port 15 along a shorter path after flowing through the heat exchanger 92, reducing the loss of the air flow during the flow process.

[0073] In addition, in some structural forms, a heat insulation layer 80 is provided on the inner surface of the first housing 20 facing the diffuser chamber 12 and the inner surface of the second housing 30 facing the diffuser chamber 12. The heat insulation layer 80 can be heat insulation sponge or heat insulation glue. In this way, by providing the heat insulation layer 80, the temperature inside the air duct assembly 10 can be maintained to a certain extent, reducing the probability of energy being dissipated outward through the first housing 20 and the second housing 30.

[0074] Refer to Figure 4 and Figure 5 In order to improve the gas flow performance during the use of the indoor unit 1, a first opening 32 is provided on the first surface 34 of the second housing 30 that forms the bottom surface of the diffuser chamber 12, and a second opening 33 is provided on the second surface 35 that forms part of the chamber wall surface of the blower chamber 11. At the same time, a return channel 31 is provided at the second housing 30, and the return channel 31 extends from the first opening 32 to the second opening 33.

[0075] The air flow driven by the fan 91 is diverted by the volute tongue 40 to flow to the diffuser chamber 12 and the side of the volute tongue 40 near the air inlet side of the fan 91 respectively. After diversion, the pressure of the air flow flowing into the diffuser chamber 12 increases, so that the air flow pressure at the first opening 32 is greater than the air flow pressure at the second opening 33. Furthermore, due to the pressure difference between the first opening 32 and the second opening 33, part of the air flow entering the diffuser chamber 12 is actively diverted back to the side of the volute tongue 40 near the air inlet side of the fan 91 through the return channel 31 to do work again. This can not only make up for the pressure on the side of the fan 91 near the volute tongue 40, thereby weakening the eddy current caused by the pressure difference, effectively improving the operating efficiency of the fan 91, improving the air intake efficiency and anti-pressure performance of the air inlet side of the fan 91, thus enhancing the overall aerodynamic performance of the air duct assembly 10. At the same time, after weakening the eddy current, the aerodynamic noise in the air duct assembly 10 can also be synchronously reduced to enhance the user experience. And because the air flow pressure at the diffuser chamber 12 is greater than the air flow pressure of the volute tongue 40, compared with the scheme of setting the first opening 32 at the volute tongue 40, the pressure difference between the first opening 32 and the second opening 33 in this application will also be greater than the scheme of setting the first opening 32 at the volute tongue 40. Furthermore, the efficiency of the air flow passing through the return channel 31 can be further improved to enhance the effect of air supplement and pressure boost.

[0076] In some structural forms, the return channel 31 is arranged in a curve. Among them, the return channel 31 can be arranged in a curve such as an arc or a wavy line. In this way, the impact speed of the air flow in the return channel 31 can be slowed down to further reduce the air flow noise and stabilize the air flow. It should be noted that the return channel 31 can also be arranged in a straight line in other embodiments. In this way, at the same fan 91 rotation speed, the air volume is increased. Or the return channel 31 can also be a combination of a straight line and a curve extending. Specifically, it can be selected by those skilled in the art according to needs.

[0077] Optionally, the width of the return channel 31 remains unchanged from the direction of the first opening 32 to the second opening 33, so as to keep the air flow flowing stably when passing through the return channel, and then stably maintain the flow rate of the air flow passing through the return channel 31 to enhance the effect of air supplement and pressure boost on the side of the fan near the volute tongue. Or in another embodiment, the width of the return channel 31 is arranged to gradually expand from the direction of the first opening 32 to the second opening 33. That is, the change amount of the width of the return channel 31 gradually increases from the first opening 32 to the second opening 33. With this setting, the change amount of the width of the return channel 31 is relatively small at the first opening 32 at the beginning, so that the air flow is evenly mixed during the process of entering the return channel 31. Then the change amount of the width of the return channel 31 continuously increases, and on the premise of ensuring that there is no flow separation in the return channel 31, the change amount of the width with the same channel length is as large as possible, which can ensure the air flow volume while reducing the air flow speed, so as to achieve the purpose of reducing noise.

[0078] Refer toFigure 6 In some embodiments, the extension line L0 of the orientation of the reflux outlet of the reflux channel 31 passes through the impeller of the fan 91, and the included angle between the extension line L0 and the outer peripheral tangent line L1 of the impeller of the fan 91 is θ, where θ is less than or equal to 15 degrees and greater than or equal to 0 degrees. In this way, while ensuring the stabilizing effect of the air flow on the eccentric vortex of the impeller of the fan 91, it is possible to avoid excessive impact of the air flow on the impeller of the fan 91, which may cause noise. When θ is greater than 15 degrees, it will cause excessive impact of the air flow on the impeller of the fan 91, thereby causing the fan 91 to vibrate and generate noise. When θ is less than 0 degrees, it will result in a poor supplementary effect of the air flow on the impeller of the fan 91, that is, the effect of stabilizing the eccentric vortex of the impeller of the fan 91 through the air flow is poor. Exemplarily, θ can be 0 degrees, 2 degrees, 5 degrees, 7 degrees, 10 degrees, 12 degrees or 15 degrees, etc., and the embodiments of the present application are not limited thereto.

[0079] Furthermore, θ is equal to 0 degrees. In this way, the extension line L0 of the orientation of the second opening 33 of the reflux channel 31 coincides with the outer peripheral tangent line L1 of the impeller of the fan 91, so that the air flow flowing out through the second opening 33 can not only have a stabilizing effect on the eccentric vortex of the impeller of the fan 91, but also avoid impacting the fan 91 and prevent noise generation.

[0080] In some embodiments, with reference to Figure 6 the extension line L0 of the orientation of the second opening 33 of the reflux channel 31 passes through the outside of the impeller of the fan 91, and the included angle between the extension line L0 and the outer peripheral tangent line L1 of the impeller of the fan 91 is β, where β is less than or equal to 45 degrees and greater than or equal to 0 degrees. In this way, while ensuring the stabilizing effect of the air flow on the eccentric vortex of the impeller of the fan 91, it is possible to avoid excessive impact of the air flow on the impeller of the fan 91, which may cause noise. When β is less than 0 degrees, it will cause excessive impact of the air flow on the impeller of the fan 91, thereby causing the impeller of the fan 91 to vibrate and generate noise. When θ is greater than 0 degrees, it will result in a poor supplementary effect of the air flow on the impeller of the fan 91, that is, the effect of stabilizing the eccentric vortex of the impeller of the fan 91 through the air flow is poor. Exemplarily, β can be 0 degrees, 10 degrees, 20 degrees, 30 degrees, 40 degrees, 45 degrees, etc., and the embodiments of the present application are not limited thereto.

[0081] Furthermore, β is equal to 0 degrees. In this way, the extension line L0 of the orientation of the second opening 33 of the reflux channel 31 coincides with the outer peripheral tangent line L1 of the impeller of the fan 91, so that the air flow flowing out through the second opening 33 can not only have a stabilizing effect on the eccentric vortex of the impeller of the fan 91, but also avoid impacting the fan 91 and prevent noise generation.

[0082] In some structural forms, the second housing 30 further includes a connecting surface (not shown) connected between the first surface 34 and the second surface 35. The connecting surface is recessed to form an air flow groove. One end of the air flow groove penetrates through the first surface 34 to communicate with the first opening 32, and the other end of the air flow groove penetrates through the second surface 35 to communicate with the second opening 33. The volute tongue 40 covers the connecting surface, so that the air flow groove forms a return channel 31. In this way, by setting the air flow groove on the connecting surface to form the return channel 31, the process difficulty is low and it is convenient for processing. At the same time, when maintenance personnel need to clean and maintain the inside of the return channel 31 later, after removing the volute tongue 40, the connecting surface is exposed, so that the air flow groove forming the return channel 31 can be directly cleaned and maintained, thereby facilitating the regular cleaning of the return channel 31 and ensuring the smoothness of the return channel 31.

[0083] Referring to Figure 5 and Figure 6 , in some structural forms, the first housing 20 may include a blower chamber front shell 24, a blower chamber upper shell 21, a diffuser chamber upper shell 22, and a heat exchange chamber upper shell 23 connected in sequence. The second housing 30 includes a diffuser chamber lower shell 50, a support member 37, and a deflector 38. The diffuser chamber lower shell 50 is provided with a first surface 34. The first surface 34 constituting the bottom surface of the diffuser chamber 12 is used to guide the air flow to the heat exchange chamber 13. And the diffuser chamber lower shell 50 is connected to the volute tongue 40. The support member 37 is connected to the side of the diffuser chamber lower shell 50 facing away from the first surface 34 and is connected to the volute tongue 40. In this way, the volute tongue 40 is connected by the diffuser chamber lower shell 50 and the support member 37 at the same time to improve the position stability of the volute tongue 40 after connection. The deflector 38 is connected to the side of the diffuser chamber lower shell 50 facing away from the first surface 34, and the deflector 38 and the support member 37 cooperate to form the second opening 33.

[0084] Among them, the blower chamber front shell 24, the blower chamber upper shell 21, the volute tongue 40, and the end of the deflector 38 away from the diffuser chamber lower shell 50 cooperate to define the blower chamber 11. Further, the blower chamber front shell 24, the blower chamber upper shell 21, the diffuser chamber upper shell 22, and the heat exchange chamber upper shell 23 can be of an integral structure to improve the connection firmness of the three and reduce the assembly steps. The diffuser chamber upper shell 22 cooperates with the volute tongue 40 and the diffuser chamber lower shell 50 to define the diffuser chamber 12.

[0085] In addition, the second housing 30 further includes a water receiving tray 60. The water receiving tray 60 is located below the heat exchanger 92 and is used to receive the condensed water flowing out from the heat exchanger 92, and cooperates with the upper housing 23 of the heat exchange cavity of the first housing 20 to define the heat exchange cavity 13. Further, the lower housing 50 of the diffuser cavity and the water receiving tray 60 can be an integrally formed member, making the connection between the two more firm and reducing the assembly steps to improve the assembly efficiency. Of course, in other structural forms, the lower housing 50 of the diffuser cavity and the water receiving tray 60 can be a split structure, and the two can be fixed by snap connection or threaded connection. The present application does not limit this.

[0086] One side of the support member 37 facing away from the volute tongue 40 is configured as a first air return surface 371. And it is spaced from the support member 37. One side of the guide member 38 facing the support member 37 is configured as a second air return surface 3821. A return air channel 31 is formed by the cooperation between the second air return surface 3821 and the first air return surface 371. In this way, the return air channel 31 is formed by the cooperation between the support member 37 and the guide member 38, that is, a split structure design is adopted to form the return air channel 31 and the second opening 33. In this way, it is convenient to disassemble and control to change the shape of the return air channel 31, and it is easier to control the orientation of the second opening 33.

[0087] Combined with reference to Figures 7 to 9 Furthermore, in order to reduce the deformation of the guide member 38 and the support member 37 when the air flow passes through the return air channel 31, at least one guide rib 39 is provided on one of the first air return surface 371 and the second air return surface 3821, and the other of the first air return surface 371 and the second air return surface 3821 abuts against at least one guide rib 39. In this way, the guide rib 39 can provide support for the guide member 38 and the support member 37, and further improve the deformation at the guide member 38 and the support member 37.

[0088] Furthermore, the guide rib 39 protrudes from the first air return surface 371 and is integrally formed with the first air return surface 371, and the second air return surface 3821 abuts against the guide rib 39. Or, in another embodiment, the guide rib 39 protrudes from the second air return surface 3821 and is integrally formed with the second air return surface 3821, and the first air return surface 371 abuts against the guide rib 39. In this way, the guide rib 39 is integrally provided with one of the first air return surface 371 and the second air return surface 3821 and abuts against the other. The attachment area of the guide rib 39 is larger, the structural stability is stronger, the interaction force between the guide rib 39, the guide member 38 and the support member 37 is stronger, and it is less likely to deform.

[0089] Optionally, combined with reference to Figures 7 to 9, one of the first air return surface 371 and the second air return surface 3821 is provided with a plurality of flow guiding ribs 39. The plurality of flow guiding ribs 39 are arranged side by side and spaced along the transverse direction of the return passage 31. The plurality of flow guiding ribs 39 divide the first opening 32 into a plurality of sub-inlets. The transverse direction of the return passage 31 is perpendicular to the direction of the airflow in the return passage 31 and perpendicular to the direction of the first air return surface 371 facing the second air return surface 3821. Refer to Figure 10 , the direction indicated by the arrow T is the transverse direction of the return passage 31. In this way, by arranging a plurality of flow guiding ribs 39, the structural stability of the flow guiding member 38 and the support member 37 is further improved. At the same time, the first opening 32 is divided into a plurality of sub-inlets by the plurality of flow guiding ribs 39, and the return passage 31 is divided into a plurality of sub-air ducts. The airflow separated from the diffuser chamber 12 is separated into multiple airflows and led out of the diffuser chamber 12, and the pressure of the airflow entering the return passage 31 is divided. The airflow pressure entering a single sub-air duct is small, and the acting force of the airflow in each sub-air duct on the flow guiding member 38 and the support member 37 is also small, reducing the impact on the flow guiding member 38 and the support member 37, thereby further reducing the situation that the flow guiding member 38 and the support member 37 are deformed due to the airflow entering the return air duct.

[0090] Combined with reference to Figure 5 , Figure 10 and Figure 11 , further, the air duct assembly 10 further includes a plurality of clamping blocks 393. Each clamping block 393 protrudes from the flow guiding rib 39 located on the first air return surface 371 and is integrally formed with the flow guiding rib 39. The second air return surface 3821 is provided with a plurality of clamping position openings 3822. Each clamping block 393 is inserted into one of the clamping position openings 3822. In this way, during assembly, the clamping block 393 is inserted into the corresponding clamping position opening 3822, and the alignment of the flow guiding member 38 and the support member 37 can be quickly completed. The assembly is convenient, effectively improving the alignment stability of the flow guiding member 38 and the support member 37, and can also effectively prevent the flow guiding member 38 and the support member 37 from deforming when the wind pressure is too high.

[0091] Optionally, the flow guiding rib 39 extends along the longitudinal direction of the return passage 31 and from the first opening 32 to the side where the second opening 33 is located. The longitudinal direction of the return passage 31 is the direction of the airflow in the return passage 31. One of the first air return surface 371 and the second air return surface 3821 is provided with a plurality of flow guiding ribs 39. The plurality of flow guiding ribs 39 are arranged side by side and spaced along the transverse direction of the return passage 31. The transverse direction of the return passage 31 is perpendicular to the direction of the airflow in the return passage 31 and perpendicular to the direction of the first air return surface 371 facing the second air return surface 3821. In this way, the flow guiding rib 39 penetrates the return passage 31 along the longitudinal direction of the return passage 31, making the state of the airflow flowing out of the return passage 31 stable and reducing the wind resistance of the airflow flowing to the air inlet side of the fan 91.

[0092] Furthermore, in the lateral direction of the return channel 31, the spacing between two adjacent flow guiding ribs 39 is equal, which is convenient for processing and ensures the overall force balance when the support member 37 and the flow guiding member 38 are installed.

[0093] Of course, the spacing between two adjacent flow guiding ribs 39 may also be unequal. It can be understood that in the lateral direction of the return channel 31, the air flow pressure in each area of the return channel 31 may be different. In the area with stronger air flow pressure, the acting force of the air flow on the support member 37 and the flow guiding member 38 is stronger, and the support member 37 and the flow guiding member 38 at this position are more likely to deform. Based on this, in the lateral direction of the return channel 31, the return channel 31 includes a plurality of return air areas arranged side by side, and the air flow pressure between two adjacent return air areas is different. The spacing between two adjacent flow guiding ribs 39 in the return air area with larger air flow pressure is a1, and the spacing between two adjacent flow guiding ribs 39 in the return air area with smaller air flow pressure is a2, where a2 > a1. In this way, in the lateral direction of the return channel 31, when the air flow pressure in the middle area is larger and the air flow pressure in the edge area is smaller, in the direction from the edge area to the middle area, the spacing between two adjacent flow guiding ribs 39 gradually decreases, that is, the plurality of flow guiding ribs 39 are distributed in a state where they are denser in the middle and looser at the edge.

[0094] Refer to Figure 10 , optionally, at least one flow guiding rib 39 provided on one of the first return air surface 371 and the second return air surface 3821 has two third surfaces 391 arranged oppositely, and the parts of the two third surfaces 391 facing the same side protrude perpendicularly or obtusely from one of the first return air surface 371 and the second return air surface 3821. In this way, the flow guiding rib 39 has a larger connection area with the corresponding flow guiding member 38 and support member 37, improving the installation stability of the flow guiding rib 39.

[0095] Furthermore, the flow guiding rib 39 has a fourth surface 392 connected between the two third surfaces 391, and the fourth surface 392 abuts against the other of the first return air surface 371 and the second return air surface 3821. To improve the support stability of the flow guiding rib 39 for the support member 37 and the flow guiding member 38. For example, when the two third surfaces 391 of the flow guiding rib 39 are both connected to the first return air surface 371, the fourth surface 392 fits with the second return air surface 3821; when the two third surfaces 391 of the flow guiding rib 39 are both connected to the second return air surface 3821, the fourth surface 392 fits with the first return air surface 371.

[0096] Optionally, in the direction where the first opening 32 of the return channel 31 faces the second opening 33, the vertical distance between the two third surfaces 391 gradually decreases or remains unchanged. Considering that the air flow pressure at the first opening 32 is relatively high and the air flow pressure at the second opening 33 is relatively low, preferably, in the direction where the first opening 32 of the return channel 31 faces the return outlet 33, the vertical distance between the two third surfaces 391 in the transverse direction of the return channel 31 gradually decreases, so that the flow area of the sub-air duct gradually increases.

[0097] In some structural forms, the diffuser chamber lower shell 50 and the support member 37 are of an integral structure. This not only saves the installation steps, but also improves the structural strength of the diffuser chamber lower shell 50 and the support member 37, and further reduces the deformation of the support member 37 caused by the air flow impact in the return channel 31. Similarly, the diffuser chamber lower shell 50 and the flow guide member 38 can also be of an integral structure. This can also improve the structural strength of the flow guide member 38.

[0098] Refer to Figure 5 and Figure 11 In some structural forms, the flow guide member 38 includes a connecting portion 381, a flow guiding portion 382, and a cavity wall portion 383. The connecting portion 381 is stacked on the side of the diffuser chamber lower shell 50 facing away from the first surface 34 and is detachably mounted on the diffuser chamber lower shell 50. Among them, the connecting portion 381 can be arranged as a flat plate and is stacked and attached to the diffuser chamber lower shell 50, so as to increase the contact area between the two, and further improve the connection stability. The flow guiding portion 382 is connected to the connecting portion 381 at an angle and has a second air return surface 3821. The flow guiding portion 382 is used to cooperate with the support member 37 to form the return channel 31 and the second opening 33. The flow guiding portion 382 can be arranged as an arc-shaped plate, so as to facilitate guiding the air flow direction. The cavity wall portion 383 is connected to the end of the flow guiding portion 382 facing away from the connecting portion 381 at an angle and extends in the direction away from the diffuser chamber lower shell 50. In this way, the cavity wall portion 383 is used to cooperate to form a part of the cavity wall of the fan chamber 11, so that the cavity wall portion 383 can also play a role in guiding the air flow to the fan 91. The connecting portion 381, the flow guiding portion 382, and the cavity wall portion 383 can be of an integral structure, so as to improve the overall structural stability of the flow guide member 38. Of course, the above three can also be separately arranged to facilitate the maintenance and replacement of single components in the later stage.

[0099] Further, the connecting portion 381 has a first connecting hole, the diffuser chamber lower shell 50 has a second connecting hole corresponding to the first connecting hole, and the air duct assembly 10 further includes a fastener that sequentially passes through the second connecting hole and the first connecting hole to fix the connecting portion 381 to the diffuser chamber lower shell 50. Among them, the first connecting hole and the second connecting hole may be threaded holes, and the fastener may be a screw. Using the screw to fix the connecting portion 381 to the diffuser chamber lower shell 50, this fixing method is relatively simple to install and easy to disassemble, facilitating subsequent maintenance and repair.

[0100] In order to prevent foreign objects from entering the fan chamber 11, the diffuser chamber 12, and the heat exchange chamber 13, the air duct assembly 10 further includes a grille 98. The grille 98 is detachably connected to the chamber wall portion 383 and covers the air inlet side of the fan chamber 11. By providing the grille 98 to cover the air inlet side of the fan 91, the fan 91 and the heat exchanger 92 are protected. In this way, the service life of the air duct assembly 10 can be extended. The grille 98 can be detachably connected to the chamber wall portion 383, which can improve the stability of the installation of the grille 98, and there is no need to separately provide other structures to connect the grille 98, reducing the number of structures of the air duct assembly 10 and shrinking the volume of the air duct assembly 10, realizing the miniaturization of the indoor unit 1. Of course, in order to further improve the stability of the connection of the grille 98, the grille 98 can also be additionally connected to the first housing 20 to further improve the stability of the connection of the grille 98.

[0101] Further, one of a fixing buckle and a fixing card slot 3831 is provided at one end of the chamber wall portion 383 facing away from the guiding portion 382, and the other of the fixing buckle and the fixing card slot 3831 is provided on the grille 98. The fixing buckle and the fixing card slot 3831 are engaged with each other. By setting the combination form of the fixing buckle and the fixing card slot 3831 in this way, not only the stability when the chamber wall portion 383 and the grille 98 are relatively fixed is ensured, but also no other tools are needed for disassembly, reducing the subsequent disassembly difficulty.

[0102] In the drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present application, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present 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. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be understood as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0103] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. An air duct assembly, characterized in that, Comprising: A first housing; And A second housing, the first housing and the second housing cooperate to define a communicating fan chamber and a diffuser chamber, a fan is disposed in the fan chamber, a volute tongue is provided at the transition between the fan chamber and the diffuser chamber, the fan drives external air flow into the fan chamber, and the volute tongue guides at least part of the air flow from the fan chamber into the diffuser chamber; The second housing includes a return passage, a first surface constituting the bottom surface of the diffuser chamber, and a second surface constituting a part of the chamber wall surface of the fan chamber, the first surface is provided with a first opening, the second surface is provided with a second opening, and the return passage extends from the first opening to the second opening.

2. The air duct assembly according to claim 1, wherein The return passage is curved.

3. The air duct assembly according to claim 1, characterized in that, The width of the return passage remains unchanged or is gradually expanded from the direction of the first opening to the second opening.

4. The air duct assembly according to claim 1, characterized in that, The extension line of the orientation of the second opening of the return passage passes through the fan, and the included angle with the outer peripheral tangent of the fan is θ, and the θ is less than or equal to 15 degrees and greater than or equal to 0 degrees; Alternatively, the extension line of the orientation of the second opening of the return passage passes through from the outside of the fan, and the included angle with the outer peripheral tangent of the fan is β, and the β is less than or equal to 45 degrees and greater than or equal to 0 degrees.

5. The air duct assembly according to claim 4, characterized in that The θ is equal to 0 degrees or the β is equal to 0 degrees, so that the extension line of the orientation of the second opening of the return passage coincides with the outer peripheral tangent of the fan.

6. The air duct assembly according to any one of claims 1 to 5, characterized in that, The second housing further includes an interface surface connected between the first surface and the second surface, the interface surface is recessed to form an air flow groove, one end of the air flow groove penetrates through the first surface to communicate with the first opening, the other end of the air flow groove penetrates through the second surface to communicate with the second opening, and the volute tongue covers the interface surface, so that the air flow groove forms the return passage.

7. The air duct assembly according to any one of claims 1 to 5, characterized in that, The second housing includes: A diffuser chamber lower housing, the diffuser chamber lower housing is provided with the first surface, and the diffuser chamber lower housing is connected to the volute tongue; A support member, the support member is connected to the side of the diffuser chamber lower housing facing away from the first surface and is connected to the volute tongue, and the side of the support member facing away from the volute tongue is configured as a first air return surface; and A deflector member, the deflector member is connected to the side of the diffuser chamber lower housing facing away from the first surface and is spaced from the support member, the side of the deflector member facing the support member is configured as a second air return surface, the second air return surface and the first air return surface cooperate to form the return passage, and the deflector member and the support member cooperate to form the second opening.

8. The air duct assembly according to claim 7, wherein At least one flow guiding rib is provided on one of the first air return surface and the second air return surface, and the other of the first air return surface and the second air return surface abuts against the at least one flow guiding rib.

9. The air duct assembly according to claim 8, wherein, The flow guiding rib protrudes from the first air return surface and is integrally formed with the first air return surface, and the second air return surface abuts against the flow guiding rib; and / or, The flow guiding rib protrudes from the second air return surface and is integrally formed with the second air return surface, and the first air return surface abuts against the flow guiding rib.

10. The air duct assembly according to claim 8, characterized in that, One of the first air return surface and the second air return surface is provided with a plurality of the flow guiding ribs, the plurality of the flow guiding ribs are arranged side by side and at intervals in the transverse direction of the return air channel, and the plurality of the flow guiding ribs divide the first opening into a plurality of sub-inlets. The transverse direction of the return air channel is perpendicular to the air flow direction in the return air channel and perpendicular to the direction of the first air return surface facing the second air return surface.

11. The air duct assembly according to claim 10, characterized in that, The air duct assembly further includes a plurality of clamping blocks, each of the clamping blocks protrudes from the flow guiding rib located on the first air return surface and is integrally formed with the flow guiding rib; a plurality of clamping openings are formed in the second air return surface, and each of the clamping blocks is inserted into one of the clamping openings.

12. The air duct assembly according to claim 8, wherein, The flow guiding rib extends along the longitudinal direction of the return air channel and from the first opening toward the side where the second opening is located. The longitudinal direction of the return air channel is the air flow direction in the return air channel. One of the first air return surface and the second air return surface is provided with a plurality of the flow guiding ribs, the plurality of the flow guiding ribs are arranged side by side and at intervals in the transverse direction of the return air channel. The transverse direction of the return air channel is perpendicular to the air flow direction in the return air channel and perpendicular to the direction of the first air return surface facing the second air return surface.

13. The air duct assembly according to claim 12, characterized in that, In the transverse direction of the return air channel, the distance between two adjacent flow guiding ribs is equal.

14. The air duct assembly according to claim 12, characterized in that, In the transverse direction of the return air channel, the return air channel includes a plurality of return air areas arranged side by side, and the air flow pressures of two adjacent return air areas are different. The distance between two adjacent flow guiding ribs in the return air area with a larger air flow pressure is a1, and the distance between two adjacent flow guiding ribs in the return air area with a smaller air flow pressure is a2, and a2 > a1.

15. The air duct assembly according to claim 12, characterized in that, At least one of the flow guiding ribs provided on one of the first air return surface and the second air return surface has two third surfaces arranged oppositely, and the parts of the two third surfaces facing the same side protrude perpendicularly or at an obtuse angle from one of the first air return surface and the second air return surface.

16. The air duct assembly according to claim 15, characterized in that, The flow guiding rib has a fourth surface connected between the two third surfaces, and the fourth surface abuts against the other of the first air return surface and the second air return surface.

17. The air duct assembly according to claim 15, characterized in that, In the direction from the first opening to the second opening of the return air channel, the vertical distance between the two third surfaces gradually decreases or remains unchanged.

18. The air duct assembly according to claim 7, wherein, The diffuser chamber lower shell and the support member are of an integral structure.

19. The air duct assembly according to claim 7, wherein, The diffuser chamber lower shell and the flow guiding member are of an integral structure.

20. The air duct assembly according to claim 7, wherein, The flow guiding member includes a connecting portion, a flow guiding portion, and a chamber wall portion. The connecting portion is laminated on the side of the diffuser chamber lower shell facing away from the first surface and is detachably mounted on the diffuser chamber lower shell. The flow guiding portion is connected to the connecting portion at an angle, and the flow guiding portion and the support member cooperate to form the return air channel and the second opening. The chamber wall portion is connected to the end of the flow guiding portion facing away from the connecting portion at an angle and extends in a direction away from the diffuser chamber lower shell.

21. The air duct assembly according to claim 20, wherein, The connecting portion has a first connecting hole, and the diffuser chamber lower shell has a second connecting hole corresponding to the first connecting hole. The air duct assembly further includes: A fastener passes through the second connecting hole and the first connecting hole in sequence to fix the connecting portion to the lower shell of the diffuser chamber.

22. The air duct assembly according to claim 20, characterized in that, The air duct assembly also includes a grille, which is detachably connected to the cavity wall portion and covers the air inlet side of the fan cavity.

23. The air duct assembly according to claim 22, characterized in that, One end of the cavity wall portion away from the guide portion is provided with one of a fixing buckle and a fixing slot, and the other of the fixing buckle and the fixing slot is provided on the grille, and the fixing buckle is engaged with the fixing slot.

24. An indoor unit, characterized in that, Comprising the air duct assembly as claimed in any one of claims 1 to 23.

25. The indoor unit according to claim 24, characterized in that, The indoor unit is a duct unit, and the fan is a cross-flow fan.

26. A heating, ventilation and air conditioning system, characterized in that, It comprises an outdoor unit and an indoor unit as described in claim 24 or 25, and the indoor unit and the outdoor unit form a refrigerant cycle.

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