Fresh air device and air conditioner indoor unit

Abstract

The invention relates to the technical field of fresh air devices, in particular to a fresh air device and an air conditioner indoor unit. The problem that a filter is easy to block in the prior art is solved, and the practicability of equipment is improved. The device structurally comprises a box body, a first air inducing pipe and a first exhaust pipe are arranged on the box body, a filter screen is arranged in the first air inducing pipe, a filter screen replacement box is arranged on the upper side of the first air inducing pipe, a filter screen storage box is arranged on the lower side of the first air inducing pipe, and a screen replacement structure used for automatically replacing the filter screen when the filter screen is blocked is arranged between the filter screen replacement box and the filter screen storage box. The box body is further provided with a second air inducing pipe and a second exhaust pipe, the first air inducing pipe and the second air inducing pipe are both connected with induced draft fans, and a heat exchange structure used for exchanging air heat in the first air inducing pipe and air heat in the second air inducing pipe is arranged in the box body. According to the embodiment, the design of fixedly installing the filter screen in the prior art is replaced, the maintenance period of the filter screen is prolonged, and high practicability is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of fresh air devices, and in particular to a fresh air device and an indoor unit of an air conditioner. Background Art

[0002] A fresh air device is a device system that introduces fresh air from outside through active ventilation and exhausts dirty air from indoors. It is usually used in environments where air quality needs to be guaranteed and comfort needs to be improved, such as modern high-sealing buildings, residences, offices, schools, hospitals, etc. As modern buildings are well sealed, indoor air is prone to accumulate harmful substances, such as carbon dioxide, formaldehyde, bacteria, viruses, moisture, etc. The use of a fresh air system can effectively solve this problem.

[0003] In order to prevent solid impurities (such as PM2.5) in the outside air from entering the room, the prior art sets a filter in the air inlet duct, and uses the filter to filter the polluted particles to prevent indoor air from being polluted.

[0004] Although this can filter the outside air, there are still the following problems: after the filter is used for a long time, polluted solid particles may accumulate on the filter, causing the filter to be blocked, reducing the frequency of exchange between outside air and indoor air. Summary of the invention

[0005] The present invention provides a fresh air device and an air conditioner indoor unit, which solves the problem of easy clogging of filters in the prior art and improves the practicability of the equipment.

[0006] The technical solution of the present invention is as follows: Fresh air device, used for indoor unit of air conditioner, including box body, The box body is provided with a first air duct and a first exhaust duct, a filter is provided in the first air duct, a filter replacement box is provided on the upper side of the first air duct, a filter storage box is provided on the lower side of the first air duct, a filter changing structure for automatically replacing the filter when the filter is clogged is provided between the filter replacement box and the filter storage box, the box body is also provided with a second air duct and a second exhaust duct, both the first air duct and the second air duct are connected to an air fan, and a heat exchange structure for exchanging the heat of the air in the first air duct and the heat of the air in the second air duct is provided in the box body.

[0007] Furthermore, the screen changing structure includes an abutment member, filter installation boxes are provided on both sides of the air duct, the filter is slidably connected to the filter installation box, a mounting plate is fixed in the filter installation box, a limiting bolt is slidably connected to the mounting plate, one end of the limiting bolt is fixedly connected to the filter, a first limiting spring is sleeved on the limiting bolt, two ends of the first limiting spring are respectively fixedly connected to the abutment member and the mounting plate, and the abutment member abuts against the filter.

[0008] Furthermore, a first mesh changing hole is provided between the first air duct and the filter replacement box, and a second mesh changing hole is provided between the first air duct and the filter storage box. The vertical projection surfaces of the first mesh changing hole and the second mesh changing hole are both rectangular structures, and the vertical projection surfaces of the first mesh changing hole and the second mesh changing hole partially overlap.

[0009] Furthermore, a connecting box is connected between the filter installation boxes, and the connecting box is arranged below the first air duct. The connecting box is connected to the filter storage box, and a third mesh changing hole is provided between the connecting box and the filter storage box, and the projection surface of the third mesh changing hole in the vertical direction coincides with the projection surface of the second mesh changing hole in the vertical direction. The abutment includes a first abutment plate and a second abutment plate, and the first abutment plate and the second abutment plate are respectively arranged in the filter installation boxes on both sides and are slidably connected to the filter installation boxes, and a sealing plate is fixed between the first abutment plate and the second abutment plate, and the sealing plate is slidably connected to the connecting box, and the sealing plate abuts against the third mesh changing hole.

[0010] Furthermore, a limit plate is fixed in the filter replacement box, and a plurality of sliding rods are slidably connected to the limit plate. A third abutment plate is also provided in the filter replacement box, and each of the sliding rods is fixedly connected to the third abutment plate. A second limit spring is also sleeved on the sliding rod, and both ends of the second limit spring are respectively fixedly connected to the third abutment plate and the limit plate.

[0011] Furthermore, the filter storage box includes an insertion portion and a storage portion, a guide portion is connected between the insertion portion and the storage portion, the insertion portion is connected to a connection box, and a box door is rotatably connected to a side wall of the storage portion.

[0012] Furthermore, the heat exchange structure includes a heat exchange box, in which a plurality of heat exchange plates are fixed, and gaps are provided between each of the heat exchange plates. The heat exchange box is also provided with a first heat exchange tube, a second heat exchange tube, a third heat exchange tube and a fourth heat exchange tube, and the first heat exchange tube, the second heat exchange tube, the third heat exchange tube and the fourth heat exchange tube all pass through the heat exchange plates.

[0013] Furthermore, a plurality of fresh air cavities and a plurality of indoor air cavities are respectively provided between the heat exchange tubes, and the fresh air cavities and the indoor air cavities are distributed at intervals, the first heat exchange tube and the fourth heat exchange tube are both connected to the fresh air cavities, the second heat exchange tube and the third heat exchange tube are both connected to the indoor air cavities, one end of the first heat exchange tube is closed, and the other end of the first heat exchange tube is connected to the first induced air duct, one end of the second heat exchange tube is closed, and the other end of the second heat exchange tube is connected to the first exhaust air duct, one end of the third heat exchange tube is closed, and the other end of the third heat exchange tube is connected to the second induced air duct, one end of the fourth heat exchange tube is closed, and the other end of the fourth heat exchange tube is connected to the second exhaust air duct.

[0014] Another object of the present invention is to provide an air conditioner indoor unit, comprising an outer shell, wherein a fresh air device is disposed in the outer shell, and the fresh air device is the fresh air device according to any one of claims 1 to 8.

[0015] Furthermore, the outer shell is provided with an air inlet and an air outlet, the air inlet is provided with a filter, the air inlet is connected to the first air duct, the outer shell is provided with an air inlet box and an air outlet box, the air inlet box is connected to the air inlet, and the air outlet box is connected to the air outlet.

[0016] The working principle and beneficial effects of the present invention are: The working process of this embodiment is as follows: when the filter is clogged, the air pressure at the filter end close to the first induced draft fan rises under the action of the first induced draft fan, driving the filter to move toward the second mesh changing hole, and the filter flows into the filter storage box from the second mesh changing hole and the third mesh changing hole. At this time, since the original filter position is vacant, the filter in the filter replacement box enters the first induced draft duct from the first mesh changing hole, and the abutment part separates from the original filter and, under the action of the limit spring, the filter is installed and positioned at the original filter position, thereby completing the automatic replacement of the filter.

[0017] In this embodiment, a first air duct is arranged on the box body, and a filter replacement box and a filter storage box are respectively arranged on the upper and lower sides of the first air duct. The filter is automatically replaced by the filter changing structure when the filter is blocked, thereby replacing the design of fixedly installing the filter in the prior art. The present invention extends the maintenance period of the filter and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0019] Figure 1 It is a structural schematic diagram of the prior art; Figure 2 This is a schematic diagram of the overall structure of this embodiment; Figure 3 is a schematic diagram of the internal structure of the outer shell in this embodiment; Figure 4 Schematic diagram of the internal structure of the box in this embodiment; Figure 5 Schematic diagram of the structure of the heat exchange box in this embodiment; Figure 6 Schematic diagram of the structure of the screen changing structure in this embodiment; Figure 7 The internal structure of the screen changing structure in this embodiment is shown in FIG. Figure 1 ; Figure 8is a schematic diagram of the connection structure of the filter screen in the first air duct in this embodiment; Fig. 9 The internal structure of the screen changing structure in this embodiment is shown in FIG. Figure 2 .

[0020] In the figure: 1. Outer shell; 11. Air outlet; 111. Air outlet box; 12. Air inlet; 121. Filter element; 122. Air inlet box; 2. Box; 3. Heat exchange box; 31. First heat exchange tube; 32. Second heat exchange tube; 321. Second exhaust duct; 33. Third heat exchange tube; 331. Second induced air duct; 34. Fourth heat exchange tube; 341. First exhaust duct; 35. Heat exchange plate; 36. Fresh air cavity; 37. Indoor air cavity; 4. First induced air duct; 41. Second mesh hole; 5. Filter replacement Box; 51. limit plate; 52. sliding rod; 53. second limit spring; 54. third abutment plate; 55. first mesh changing hole; 6. filter storage box; 61. box door; 62. insertion part; 63. guide part; 64. storage part; 65. third mesh changing hole; 7. filter installation box; 71. abutment; 711. first abutment plate; 712. second abutment plate; 713. sealing plate; 72. limit bolt; 73. first limit spring; 74. installation plate; 8. filter; 9. connection box. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] like Figure 2~Figure 9 As shown, this embodiment proposes a fresh air device for an indoor unit of an air conditioner, and its structure includes a box body 2.

[0023] In this embodiment, the first air duct 4 and the first exhaust duct 341 are arranged in the housing 2. Among them, the first air duct 4 is used to introduce fresh air from the outside, and the first exhaust duct 341 is used to discharge fresh air to the room. The filter 8 is arranged in the first air duct 4 to filter impurities in the outside air to prevent indoor air pollution. The filter replacement box 5 is arranged on the upper side of the first air duct 4 to store clean filters for convenient replacement of the filters. The filter storage box 6 is arranged on the lower side of the first air duct 4 to store clogged filters for convenient collection and centralized treatment of clogged filters. The filter replacement structure is arranged between the filter replacement box 5 and the filter storage box 6 to automatically replace the filter 8 when the filter 8 is clogged. The second air duct 331 and the second exhaust duct 321 are arranged on the housing 2. Among them, the second air duct 331 is used to introduce polluted air in the room, and the second exhaust duct 321 is used to discharge polluted air in the room to the outside. The first air duct 4 and the second air duct 331 are both connected with an air duct fan to provide power for introducing air. A heat exchange structure is arranged in the box body 2 to exchange the heat of air in the first air duct 4 with the heat of air in the second air duct 331.

[0024] The screen changing structure in this embodiment includes an abutment member 71, a filter screen installation box 7 is arranged on both sides of the induced air duct, a filter screen 8 is slidably connected to the filter screen installation box 7, and a mounting plate 74 is fixedly arranged in the filter screen installation box 7 for installing a limit bolt 72. The limit bolt 72 is slidably connected to the mounting plate 74 to prevent the limit bolt 72 from being separated from the mounting plate 74. One end of the limit bolt 72 is fixedly connected to the filter screen 8, and a first limit spring 73 is sleeved on the limit bolt 72. Both ends of the first limit spring 73 are fixedly connected to the abutment member 71 and the mounting plate 74 respectively, and the abutment member 71 abuts against the filter screen 8. In this embodiment, the first limiting spring 73 is used to compress the abutment 71 so that the filter 8 can be installed in the first air duct 4. When the filter 8 is not blocked, since the air can pass through the filter 8 smoothly, the air pressure difference on both sides of the filter 8 is small, and the elastic force of the first limiting spring 73 alone is sufficient to support the installation and fixation of the filter 8 relative to the air duct. When the filter 8 is blocked, the air pressure difference on both sides of the filter 8 increases, and the air pressure pushing the filter 8 to move is greater than the elastic force of the first limiting spring 73, and the filter is separated from the crude oil installation position and the filter replacement operation is performed.

[0025] In this embodiment, the first mesh changing hole 55 is arranged between the first air duct 4 and the filter changing box 5, and the second mesh changing hole 41 is arranged between the first air duct 4 and the filter storage box 6. The vertical projection surfaces of the first mesh changing hole 55 and the second mesh changing hole 41 are both rectangular structures, and the vertical projection surfaces of the first mesh changing hole 55 and the second mesh changing hole 41 partially overlap. Since the vertical projection surfaces of the first mesh changing hole 55 and the second mesh changing hole 41 partially overlap, when the blocked filter 8 does not move to the position of the second mesh changing hole 41, the filter 8 blocks the first mesh changing hole 55, and the new filter 8 will not fall into the first air duct 4, preventing it from hindering the mesh changing process.

[0026] The connection box 9 in this embodiment is connected and arranged between the filter installation boxes 7. The connection box 9 is arranged below the first induced air duct 4. The connection box 9 is connected to the filter storage box 6. The third mesh changing hole 65 is arranged between the connection box 9 and the filter storage box 6. The vertical projection surface of the third mesh changing hole 65 coincides with the vertical projection surface of the second mesh changing hole 41. The abutment 71 includes a first abutment plate 711 and a second abutment plate 712. The first abutment plate 711 and the second abutment plate 712 are respectively arranged in the filter installation boxes 7 on both sides and are slidably connected with the filter installation boxes 7 to prevent the filter 8 from sliding and deviating. The sealing plate 713 is fixedly arranged between the first abutment plate 711 and the second abutment plate 712. The sealing plate 713 is slidably connected to the connection box 9, and the sealing plate 713 abuts against the third mesh changing hole 65. The connection box 9 used in this embodiment can play the role of connecting the abutment 71, so that the abutment 71 will not deviate when it moves. This embodiment uses a sealing plate 713 to block the third screen-changing hole 65, so that under normal working conditions, gas will not enter the screen installation box 7, thereby improving the stability of equipment operation.

[0027] The limit plate 51 in this embodiment is fixedly arranged in the filter replacement box 5, a plurality of sliding rods 52 are slidingly arranged on the limit plate 51, a third abutment plate 54 is arranged in the filter replacement box 5, each sliding rod 52 is fixedly connected to the third abutment plate 54, a second limit spring 53 is sleeved on the sliding rod 52, and the two ends of the second limit spring 53 are respectively fixedly connected to the third abutment plate 54 and the limit plate 51. Such a design ensures that all filter plates to be replaced are always kept close to the side of the first mesh replacement hole 55, so that the filter 8 can be replaced as soon as possible when it is blocked. In this embodiment, a sealing door is also arranged on the filter replacement box 5 to facilitate the replenishment of the filter 8.

[0028] The filter storage box 6 in this embodiment includes an insertion portion 62 and a storage portion 64, a guide portion 63 is arranged between the insertion portion 62 and the storage portion 64, the insertion portion 62 is connected to the connection box 9, and a box door 61 is rotatably connected to the side wall of the storage portion 64. The design of the upper box door 61 in this embodiment is to facilitate the removal of the filter 8 to be blocked and to facilitate the centralized treatment of the blocked filter 8. The design of the insertion portion 62 and the guide portion 63 in this embodiment is to prevent the filter 8 from being stuck when it is placed in the storage portion 64, and to guide the filter 8 to be concentrated in the storage portion 64 for the reeling of the filter 8.

[0029] The heat exchange structure in this embodiment includes a heat exchange box 3, a plurality of heat exchange plates 35 are fixedly arranged in the heat exchange box 3, gaps are provided between the heat exchange plates 35, and the heat exchange box 3 is also provided with a first heat exchange tube 31, a second heat exchange tube 32, a third heat exchange tube 33 and a fourth heat exchange tube 34, and the first heat exchange tube 31, the second heat exchange tube 32, the third heat exchange tube 33 and the fourth heat exchange tube 34 all penetrate the heat exchange plate 35. In this embodiment, the indoor and outdoor air are heat exchanged through the heat exchange plate 35, so as to reduce the influence of the outdoor air being too cold or too hot on the indoor air temperature.

[0030] In this embodiment, a plurality of fresh air cavities 36 and a plurality of indoor air cavities 37 are arranged between the heat exchange tubes, and the fresh air cavities 36 and the indoor air cavities 37 are distributed at intervals. The first heat exchange tube 31 and the fourth heat exchange tube 34 are both connected to the fresh air cavities 36, and the second heat exchange tube 32 and the third heat exchange tube 33 are both connected to the indoor air cavities 37. One end of the first heat exchange tube 31 is closed, and the other end of the first heat exchange tube 31 is connected to the first induced air duct 4. One end of the second heat exchange tube 32 is closed, and the other end of the second heat exchange tube 32 is connected to the first exhaust air duct 341. One end of the third heat exchange tube 33 is closed, and the other end of the third heat exchange tube 33 is connected to the second induced air duct 331. One end of the fourth heat exchange tube 34 is closed, and the other end of the fourth heat exchange tube 34 is connected to the second exhaust air duct 321. In this embodiment, the outside air is introduced into the fresh air cavity 36, and the indoor exhaust air is introduced into the indoor air cavity 37. The temperatures of the two are fully exchanged through the isolation of the heat exchange plate 35, which reduces the excessive temperature difference between indoor and outdoor air and reduces the user experience of indoor users.

[0031] Another invention purpose of the present invention is to provide an air conditioner indoor unit, comprising an outer shell 1, wherein a fresh air device is arranged in the outer shell 1, and the fresh air device is the fresh air device of any one of claims 1 to 8. The air inlet 12 and the air outlet 11 in this embodiment are arranged on the outer shell 1, the filter 121 is arranged on the air inlet 12, the air inlet 12 is connected to the first air duct 4, the air inlet box 122 and the air outlet box 111 are arranged in the outer shell 1, the air inlet box 122 is connected to the air inlet 12, and the air outlet box 111 is connected to the air outlet 11. The air inlet box 122 in this embodiment is used to store and guide the polluted air in the room, and the air outlet box 111 is used to store and release the fresh air from the outside. The filter 121 used in this embodiment is used to filter the indoor air.

[0032] The working process of this embodiment is as follows: when the filter 8 is blocked, the air pressure at the end of the filter 8 close to the first induced draft fan rises under the action of the first induced draft fan, driving the filter 8 to move toward the second filter changing hole 41, and the filter 8 flows into the filter storage box 6 from the second filter changing hole 41 and the third filter changing hole 65. At this time, since the original position of the filter 8 is vacant, the filter 8 in the filter replacement box 5 enters the first induced draft duct 4 from the first filter changing hole 55, and the abutment 71 detaches from the original filter 8 and, under the action of the limit spring, installs and positions the filter 8 at the original position of the filter 8, thereby completing the automatic replacement of the filter 8.

[0033] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fresh air device, used for an indoor unit of an air conditioner, comprising a box (2), characterized in that: The housing (2) is provided with a first air induced draft duct (4) and a first air exhaust duct (341); a filter screen (8) is provided inside the first air induced draft duct (4); a filter screen replacement box (5) is provided on the upper side of the first air induced draft duct (4); a filter screen storage box (6) is provided on the lower side of the first air induced draft duct (4); a screen replacement structure for automatically replacing the filter screen (8) when the filter screen (8) is blocked is provided between the filter screen replacement box (5) and the filter screen storage box (6); a second air induced draft duct (331) and a second air exhaust duct (321) are also provided on the housing (2); both the first air induced draft duct (4) and the second air induced draft duct (331) are connected to an air induced draft fan; and a heat exchange structure for exchanging the heat of air in the first air induced draft duct (4) with the heat of air in the second air induced draft duct (331) is provided inside the housing (2).

2. The fresh air device according to claim 1, characterized in that: The screen changing structure comprises an abutment member (71), filter screen installation boxes (7) are provided on both sides of the air duct, the filter screen (8) is slidably connected to the filter screen installation box (7), a mounting plate (74) is fixed in the filter screen installation box (7), a limiting bolt (72) is slidably connected to the mounting plate (74), one end of the limiting bolt (72) is fixedly connected to the filter screen (8), a first limiting spring (73) is sleeved on the limiting bolt (72), two ends of the first limiting spring (73) are respectively fixedly connected to the abutment member (71) and the mounting plate (74), and the abutment member (71) abuts against the filter screen (8).

3. The fresh air device according to claim 2, characterized in that: A first mesh changing hole (55) is provided between the first air duct (4) and the filter replacement box (5), and a second mesh changing hole (41) is provided between the first air duct (4) and the filter storage box (6). The projection surfaces of the first mesh changing hole (55) and the second mesh changing hole (41) in the vertical direction are both rectangular structures, and the projection surfaces of the first mesh changing hole (55) and the second mesh changing hole (41) in the vertical direction partially overlap.

4. The fresh air device according to claim 2, characterized in that: A connection box (9) is connected between the filter installation boxes (7), the connection box (9) is arranged below the first air duct (4), the connection box (9) is connected to the filter storage box (6), a third filter changing hole (65) is arranged between the connection box (9) and the filter storage box (6), the projection surface of the third filter changing hole (65) in the vertical direction coincides with the projection surface of the second filter changing hole (41) in the vertical direction, the abutment member (71) comprises a first abutment plate (711) and a second abutment plate (712), the first abutment plate (711) and the second abutment plate (712) are respectively arranged in the filter installation boxes (7) on both sides and are slidably connected to the filter installation boxes (7), a sealing plate (713) is fixed between the first abutment plate (711) and the second abutment plate (712), the sealing plate (713) is slidably connected to the connection box (9), and the sealing plate (713) abuts against the third filter changing hole (65).

5. The fresh air device according to claim 1, characterized in that: A limit plate (51) is fixed in the filter replacement box (5), and a plurality of sliding rods (52) are slidably connected to the limit plate (51). A third abutment plate (54) is also provided in the filter replacement box (5), and each of the sliding rods (52) is fixedly connected to the third abutment plate (54). A second limit spring (53) is sleeved on the sliding rod (52), and two ends of the second limit spring (53) are respectively fixedly connected to the third abutment plate (54) and the limit plate (51).

6. The fresh air device according to claim 5, characterized in that: The filter storage box (6) comprises an insertion portion (62) and a storage portion (64), a guide portion (63) being connected between the insertion portion (62) and the storage portion (64), the insertion portion (62) being connected to a connection box (9), and a box door (61) being rotatably connected to a side wall of the storage portion (64).

7. The fresh air device according to claim 1, characterized in that: The heat exchange structure comprises a heat exchange box (3), a plurality of heat exchange plates (35) are fixed in the heat exchange box (3), gaps are provided between the heat exchange plates (35), and a first heat exchange tube (31), a second heat exchange tube (32), a third heat exchange tube (33) and a fourth heat exchange tube (34) are also provided on the heat exchange box (3), and the first heat exchange tube (31), the second heat exchange tube (32), the third heat exchange tube (33) and the fourth heat exchange tube (34) all pass through the heat exchange plates (35).

8. The fresh air device according to claim 7, characterized in that: A plurality of fresh air cavities (36) and a plurality of indoor air cavities (37) are respectively arranged between the heat exchange tubes. The fresh air cavities (36) and the indoor air cavities (37) are spaced apart. The first heat exchange tube (31) and the fourth heat exchange tube (34) are both in communication with the fresh air cavities (36). The second heat exchange tube (32) and the third heat exchange tube (33) are both in communication with the indoor air cavities (37). One end of the first heat exchange tube (31) is closed, and the other end of the first heat exchange tube (31) is connected to the first induced air duct (4). One end of the second heat exchange tube (32) is closed, and the other end of the second heat exchange tube (32) is connected to the first exhaust air duct (341). One end of the third heat exchange tube (33) is closed, and the other end of the third heat exchange tube (33) is connected to the second induced air duct (331). One end of the fourth heat exchange tube (34) is closed, and the other end of the fourth heat exchange tube (34) is connected to the second exhaust air duct (321).

9. An indoor unit of an air conditioner, comprising an outer shell (1), characterized in that: A fresh air device is provided in the outer shell (1), and the fresh air device is the fresh air device according to any one of claims 1 to 8.

10. The air conditioner indoor unit according to claim 9, characterized in that: The outer shell (1) is provided with an air inlet (12) and an air outlet (11); the air inlet (12) is provided with a filter element (121); the air inlet (12) is connected to a first air duct (4); an air inlet box (122) and an air outlet box (111) are provided inside the outer shell (1); the air inlet box (122) is connected to the air inlet (12); and the air outlet box (111) is connected to the air outlet (11).

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