Indoor unit of air conditioner

Abstract

To reduce noise of an indoor unit which has a humidification duct.SOLUTION: An indoor unit (20) includes a casing (21), a duct (28), and a first soundproof sheet (51). The duct (28) is for introducing the outdoor air into the casing (21), and for delivering the air in the casing (21) to the outdoors. The first soundproof sheet (51) is installed in a recess part (65) provided on an outside surface of the duct (28).SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to an indoor unit of an air conditioner, and more particularly to an indoor unit equipped with a humidifying duct that guides humidified air. [Background technology]

[0002] Patent Document 1 (JP 2023-024124 A) discloses an indoor unit of an air conditioner that is provided with a humidifying duct. The humidifying duct receives humidified air supplied from a humidifying unit installed outdoors via a hose and merges the humidified air with the airflow in the indoor unit to deliver the humidified air to a user. Summary of the Invention [Problem to be solved by the invention]

[0003] Supplying humidified air to users is also a form of ventilation that takes in outside air, which can be a source of noise. If the humidifying duct vibrates as outside air is introduced, the silence of the space where the user is present can be disturbed. For this reason, appropriate vibration countermeasures are required for the humidifying duct. [Means for solving the problem]

[0004] The indoor unit of a first aspect includes a casing, a duct, and a first soundproof sheet. The duct is for introducing outdoor air into the casing or for sending air in the casing to the outdoors. The first soundproof sheet is placed in a recess provided on the outer surface of the duct.

[0005] According to this configuration, the first soundproof sheet is provided on the outer surface of the duct, and therefore the vibration energy of the duct is converted into thermal energy, thereby reducing the noise emitted from the duct.

[0006] An indoor unit according to a second aspect is the indoor unit according to the first aspect, wherein the shape of the recess is substantially the same as the outer shape of the first soundproof sheet.

[0007] According to this configuration, when the first soundproof sheet is placed in the recess, the shapes of the two match, so that the recess can properly accommodate the soundproof sheet.

[0008] The indoor unit of a third aspect is the indoor unit of the first or second aspect, wherein the duct has a flat portion in which the cross-sectional area of ​​the air flow path is small. The flat portion extends parallel to a side surface of the casing. The recess is provided on an outer surface of the flat portion.

[0009] According to this configuration, the flat portion, the side surface of the casing, and the first soundproof sheet are all arranged in parallel, thereby effectively reducing noise.

[0010] An indoor unit according to a fourth aspect is the indoor unit according to the third aspect, wherein the flat portion and the first soundproof sheet share a common longitudinal direction.

[0011] With this configuration, the area where the flat portion and the first soundproof sheet overlap is large, so noise is reduced more effectively.

[0012] The indoor unit of a fifth aspect is the indoor unit of the third or fourth aspect, wherein the flat portion has a first surface and a second surface. The first surface faces a side surface of the casing. The second surface is parallel to the first surface. The recess is provided in the first surface.

[0013] According to this configuration, the first soundproof sheet is located between the duct and the casing, and therefore the noise emitted from the duct is prevented from reaching the casing by the first soundproof sheet.

[0014] An indoor unit according to a sixth aspect is the indoor unit according to the fifth aspect, wherein an area ratio of the recessed portion to the first surface of the flat portion is 50% or more.

[0015] According to this configuration, a certain proportion of the area of ​​the flat portion is covered by the first soundproof sheet, thereby more effectively reducing noise.

[0016] The indoor unit of a seventh aspect is the indoor unit of the fifth or sixth aspect, further comprising a second soundproof sheet. The second soundproof sheet is placed on at least one of the outside of the duct on the second surface and the inside of the duct on the first surface.

[0017] According to this configuration, the vibration of the duct is also damped by the second soundproof sheet, so that noise is further effectively reduced.

[0018] An indoor unit according to an eighth aspect is the indoor unit according to any one of the first to seventh aspects, wherein the recess has a first side on the upstream side and a second side on the downstream side. The first side and the second side are spaced apart in the direction of the air flow passing through the duct. At least one of the first side and the second side is chamfered to have a flat or curved surface.

[0019] With this configuration, the number of portions of the inner surface of the duct that form acute angles with which the airflow comes into contact is reduced, which allows the airflow to travel more smoothly and ultimately suppresses vibration of the duct.

[0020] The indoor unit of a ninth aspect is the indoor unit of the third aspect, wherein the first soundproof sheet is rectangular, square, circular, or elliptical.

[0021] According to this configuration, the area of ​​the first surface where no recess is formed occupies a certain area, so that the strength of the flat portion of the duct can be ensured.

[0022] An indoor unit according to a tenth aspect is the indoor unit according to any one of the first aspect to the ninth aspect, wherein the depth of the recess is 4 mm or less.

[0023] According to this configuration, the depth of the recess is 4 mm or less, so that a sufficient cross-sectional area of ​​the air flow path can be ensured in the flat portion where the dimension of the recess in the depth direction is originally small.

[0024] An air conditioner according to an eleventh aspect includes an indoor unit according to any one of the first to ninth aspects.

[0025] With this configuration, the noise emitted from the air conditioning device is reduced. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is an external view of an air conditioning device 100. [Diagram 2] 1 is a schematic diagram showing a refrigerant circuit and air paths of an air conditioner 100. FIG. [Diagram 3] FIG. 2 is an exploded perspective view of the indoor unit 20. [Figure 4] FIG. 2 is a top view of the indoor unit 20. [Diagram 5] FIG. 2 is a front view of the indoor unit 20. [Figure 6] 2 is a cross-sectional view corresponding to the left side surface 21L of the indoor unit 20. FIG. [Figure 7] 2 is a cross-sectional view corresponding to a right side surface 21R of the indoor unit 20. FIG. [Figure 8] FIG. 2 is a perspective view of the humidification duct 28. [Figure 9] FIG. 2 is a top view of the humidification duct 28. [Figure 10] FIG. 2 is a left side view of the humidification duct 28. [Figure 11] 4 is a right side view of the humidification duct 28. FIG. [Figure 12] FIG. 11 is a top view of a humidification duct 28 according to a first modified example. [Figure 13] FIG. 11 is a left side view of a humidification duct 28 according to a second modified example. [Figure 14] FIG. 11 is a left side view of a humidification duct 28 according to a third modified example. [Figure 15] 13 is a cross-sectional view of a flat portion 62 of a humidification duct 28 according to a third modified example. FIG. [Figure 16] 13 is a cross-sectional view of a flat portion 62 of a humidification duct 28 according to a third modified example. FIG. [Figure 17] FIG. 11 is a left side view of a humidification duct 28 according to a fourth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] <Embodiment> (1) Overall structure 1 shows an air conditioner 100 according to an embodiment of the present disclosure. The air conditioner 100 has an outdoor unit 10, an indoor unit 20, a humidification unit 30, a communication pipe group 40, an air hose 45, an internal / external communication line 49, and a humidification communication line 48.

[0028] The outdoor unit 10 extracts cold or heat from the outside air, which is a heat source. The humidification unit 30 generates humidified air. The indoor unit 20 provides the cold or heat together with the humidified air to a user.

[0029] 1, in this embodiment, the humidifying unit 30 is configured as a separate unit separated from the outdoor unit 10. Alternatively, the humidifying unit 30 may be built in the same casing as the outdoor unit 10 and configured as a single unit.

[0030] The interconnection pipe group 40 and the internal / external communication line 49 connect the outdoor unit 10 and the indoor unit 20. The interconnection pipe group 40 has a liquid interconnection pipe 41 and a gas interconnection pipe 42. The air hose 45 and the humidification communication line 48 connect the humidification unit 30 and the indoor unit 20.

[0031] (2) Configuration of each unit and connecting parts (2-1) Outdoor unit 10 As shown in FIG. 2, the outdoor unit 10 has an outdoor casing 10a, a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13, an outdoor fan 14, an outdoor expansion valve 15, an accumulator 16, a liquid stop valve 17, a gas stop valve 18, and an outdoor control unit 19.

[0032] The compressor 11 compresses the low-pressure gas refrigerant by the power of the compressor motor 11m to generate the high-pressure gas refrigerant. The four-way switching valve 12 realizes the connection shown by the solid line in FIG. 2 in the case of cooling operation, and forms the connection shown by the dashed line in the case of heating operation. The outdoor heat exchanger 13 functions as a condenser in the case of cooling operation, and functions as an evaporator in the case of heating operation. The outdoor fan 14 generates an air flow passing through the outdoor heat exchanger 13 by the power of the outdoor fan motor 14m, and promotes the heat exchange of the outdoor heat exchanger 13. The outdoor expansion valve 15 generates a low-pressure gas-liquid two-phase refrigerant by reducing the pressure of the high-pressure liquid refrigerant. The accumulator 16 separates and stores the liquid refrigerant component in the gas refrigerant. The liquid shutoff valve 17 and the gas shutoff valve 18 are used by the installer to shut off the refrigerant flow path. The outdoor control unit 19 acquires the output of various sensors, controls various actuators, and communicates with the control units of other units.

[0033] (2-2) Indoor unit 20 The indoor unit 20 has a casing 21, an indoor heat exchanger 23, an indoor fan 24, a humidifying duct 28, and an indoor control unit 29. The indoor heat exchanger 23 functions as an evaporator during cooling operation and as a condenser during heating operation. The indoor fan 24 generates an airflow passing through the indoor heat exchanger 23 by the power of an indoor fan motor 24m, and promotes heat exchange in the indoor heat exchanger 23. In addition, the indoor fan 24 sends out the conditioned air to the user. The humidifying duct 28 blows out the humidified air sent from the humidifying unit 30 toward the indoor heat exchanger 23, thereby delivering the humidified air to the user. The indoor control unit 29 acquires the outputs of various sensors, controls various actuators, and communicates with the control units of the other units.

[0034] (2-3) Humidification unit 30 The humidification unit 30 has a humidification casing 30a, an adsorption rotor 31, a heater 32, an air supply / exhaust fan 33, a switching damper 34, an adsorption fan 35, a connection section 36, and a humidification control section 39. The humidification casing 30a is provided with an adsorption air intake 301, an adsorption air outlet 302, a humidification air intake 303, and a humidification air outlet 304. The adsorption rotor 31 and the adsorption fan 35 are disposed in the air path formed between the adsorption air intake 301 and the adsorption air outlet 302. The adsorption rotor 31, the heater 32, the air supply / exhaust fan 33, the switching damper 34, and the connection section 36 are disposed in the air path formed between the humidification air intake 303 and the humidification air outlet 304.

[0035] The adsorption rotor 31 is made of a sintered adsorbent and can adsorb moisture in the air passing through it. The adsorption rotor 31 can change the area to adsorb moisture by rotating it using the adsorption rotor motor 31m. The heater 32 is provided in the middle of the air path and heats the air passing through it to create hot air, which causes the moisture held by the adsorption rotor 31 to be desorbed and creates humidified air. The supply and exhaust fan 33 generates an air flow in the air path using the supply and exhaust fan motor 33m. The switching damper 34 switches the direction of the air flow using the switching damper motor 34m. The adsorption fan 35 generates an air flow passing through the adsorption rotor 31 by the action of the adsorption fan motor 35m, thereby promoting the adsorption of moisture by the adsorption rotor 31. The connection unit 36 ​​is provided at the humidification air outlet 304 and can be connected to an air hose 45. The humidification control unit 39 acquires the output of various sensors, controls various actuators, and communicates with the control units of other units.

[0036] (2-4) Connection parts The liquid connection pipe 41 connects the liquid shutoff valve 17 and the indoor heat exchanger 23. The gas connection pipe 42 connects the gas shutoff valve 18 and the indoor heat exchanger 23. The air hose 45 connects the connection part 36 of the humidification unit 30 and the humidification duct 28 of the indoor unit 20. The indoor / outdoor communication line 49 connects the outdoor control unit 19 and the indoor control unit 29. The humidification communication line 48 connects the outdoor control unit 19 and the humidification control unit 39.

[0037] (3) Detailed configuration of indoor unit 20 3 is a schematic exploded perspective view of the indoor unit 20. The indoor unit 20 has an air filter 22 in addition to a casing 21, an indoor heat exchanger 23, and an indoor fan 24.

[0038] (3-1) Casing 21 The casing 21 houses the components of the indoor unit 20. The casing 21 extends in the casing longitudinal direction CL from the left end EL to the right end ER. The casing 21 has a frame 21f, a grill 21g, and a front panel 21p. The grill 21g is provided with an intake port 21a. The front panel 21p is provided with an outlet port 21b. An indoor heat exchanger 23 and an indoor fan 24 are installed on the frame 21f.

[0039] Fig. 4 is a top view of the indoor unit 20. Fig. 5 is a front view of the indoor unit 20. 4 and 5, a part of the casing 21 and the air filter 22 are omitted. As shown in Fig. 4 and 5, a left side surface 21L of the casing 21 forms a left end EL, and a right side surface 21R forms a right end ER.

[0040] (3-2) Air filter 22 3, the air filter 22 extends in the casing longitudinal direction CL. The air filter 22 removes dust and dirt from the air drawn in through the suction port 21a.

[0041] (3-3) Indoor heat exchanger 23 As shown in Fig. 4 and Fig. 5, the indoor heat exchanger 23 extends in the casing longitudinal direction CL. Fig. 6 is a cross-sectional view of the indoor unit 20 corresponding to the left side surface 21L. Fig. 7 is a cross-sectional view of the indoor unit 20 corresponding to the right side surface 21R. As shown in Fig. 6 and Fig. 7, the indoor heat exchanger 23 has a front heat exchange section 23F and a rear heat exchange section 23R. The front heat exchange section 23F is located above and forward of the indoor fan 24. The rear heat exchange section 23R is located above and rear of the indoor fan 24. The indoor heat exchanger 23 has a C-shape that surrounds the indoor fan 24 as a whole.

[0042] (3-4) Indoor fan 24 The indoor fan 24 is a sirocco fan and extends in the casing longitudinal direction CL as shown in Fig. 3. The indoor fan 24 draws in air from the air inlet 21a, passes it through the indoor heat exchanger 23, and then blows the air out from the air outlet 21b, as shown by the arrow in Fig. 7.

[0043] (3-5) Drain pan 26 7 receives condensation water from the indoor heat exchanger 23. The drain pans 26 are provided below the front heat exchange section 23F and below the rear heat exchange section 23R.

[0044] (3-6) Flap 27 A flap 27 shown in FIG. 7 changes the direction of travel of the conditioned air blown out from the air outlet 21b by the action of a motor (not shown).

[0045] (3-7) Humidification duct 28 The humidification duct 28 shown in Fig. 6 is for introducing outdoor air into the casing 21. Typically, the humidification duct 28 has a function of delivering humidified air sent from the humidification unit 30 to a user. As shown in Fig. 7, the humidified air outlet 28a of the humidification duct 28 faces the indoor heat exchanger 23. The humidified air HA supplied from the humidified air outlet 28a passes through the indoor heat exchanger 23, and then is released from the outlet 21b to be delivered to the user.

[0046] As shown in FIG. 4, the humidification duct 28 is disposed adjacent to the left side surface 21L of the casing 21.

[0047] The switching damper 34 of the humidifying unit 30 switches the direction of the airflow, so that the humidifying duct 28 can also send the air inside the casing 21 to the outdoors.

[0048] (4) Structure of humidification duct 28 8 to 11 show the external appearance of the humidification duct 28. FIG.

[0049] As shown in Fig. 8, the humidification duct 28 has a receiving portion 63, a flat portion 62, and an expanding portion 61. The receiving portion 63 is a portion that receives the humidified air. The receiving portion 63 is provided with a humidified air receiving port 28c. The humidified air that enters through the humidified air receiving port 28c rises inside the receiving portion 63 and then moves to the flat portion 62.

[0050] The flat portion 62 is a flat passage having a smaller cross-sectional area of ​​the air flow path than other portions. The flat portion 62 spreads parallel to the left side surface 21L of the casing 21. The flat portion 62 extends along the flat longitudinal direction FL, and the dimension in the casing longitudinal direction CL is short. The flat portion 62 has a first surface 62a and a second surface 62b parallel thereto. The first surface 62a is disposed close to the left side surface 21L so as to face the left side surface 21L of the casing 21. The surface of the first surface 62a facing the left side surface 21L constitutes a part of the outer surface of the humidifying duct 28. The distance between the left side surface 21L and the second surface 62b is larger than the distance between the left side surface 21L and the first surface 62a. The humidified air that has passed through the flat portion 62 proceeds to the development portion 61.

[0051] The expansion portion 61 extends in the casing longitudinal direction CL. The humidified air outlet 28a is provided in the expansion portion 61. As described above, the humidified air that has gone out of the humidifying duct 28 from the humidified air outlet 28a moves toward the indoor heat exchanger 23.

[0052] As shown in Fig. 9, a shallow recess 65 is provided on the first surface 62a of the flat portion 62, the surface that constitutes the outer surface of the humidification duct 28. The depth D of the recess 65 is 4 mm or less. The soundproof sheet 51 is placed in the recess 65. The shape of the recess 65 is substantially the same as the outer shape of the soundproof sheet 51. In other words, there is almost no spare space in the recess 65. As shown in Fig. 10, in this embodiment, the shape of the soundproof sheet 51 is circular.

[0053] The soundproof sheet 51 is typically a sheet-like material made of a vibration-damping material, but is not limited to this. Instead, the soundproof sheet 51 may be made of, for example, a sound-absorbing material, a sound-insulating material, or a vibration-proof material. These materials have the function of converting vibration energy into heat. The soundproof sheet 51 suppresses the transmission of noise generated in the flat portion 62 due to the pulsation of the humidified air to the outside of the casing 21.

[0054] In this embodiment, the number of recesses 65 and soundproof sheets 51 on the first surface 62a is two. Alternatively, the number of recesses 65 and soundproof sheets 51 on the first surface 62a may be one or three or more.

[0055] The area ratio of the recesses 65 to the first surface 62a is 50% or more. The area of ​​the first surface 62a other than the recesses 65 is the base 66. As can be seen from Fig. 10, the area of ​​the base 66 is large enough to be visible on the first surface 62a.

[0056] (5) Features (5-1) Soundproof sheet 51 is provided on first surface 62a of humidification duct 28. Therefore, the vibration energy of humidification duct 28 is converted into thermal energy, and the noise emitted from humidification duct 28 is reduced.

[0057] (5-2) The area ratio of the recesses 65 to the first surface 62a of the flat portion 62 is 50% or more. Therefore, a certain proportion of the area of ​​the flat portion 62 is covered by the soundproof sheet 51, so that noise is reduced more effectively.

[0058] (5-3) The shape of the soundproof sheet 51 matches the shape of the recess 65. Therefore, when the soundproof sheet 51 is placed in the recess 65, the recess 65 can accommodate the soundproof sheet 51 appropriately.

[0059] (5-4) The flat portion 62 of the humidification duct 28, the left side surface 21L of the casing 21, and the soundproof sheet 51 are all arranged in parallel, thereby effectively reducing noise.

[0060] (5-5) A soundproof sheet 51 is positioned between the humidification duct 28 and the casing 21. Therefore, the soundproof sheet 51 prevents noise emitted from the humidification duct 28 from reaching the casing 21.

[0061] (5-6) In the first surface 62a, the base portion 66 that does not form the recess 65 occupies a certain area. Therefore, the strength of the flat portion 62 of the humidification duct 28 can be ensured.

[0062] (5-7) The depth D of the recess 65 is 4 mm or less. Therefore, in the flat portion 62, which originally has a small dimension in the direction of the depth D of the recess 65, a sufficient cross-sectional area of ​​the air flow path can be ensured.

[0063] <Modifications of the embodiment> (6) Variations Modifications of the above-described embodiment will be described below. If possible, multiple modifications may be combined.

[0064] (6-1) First Modification 12 shows humidification duct 28 according to a first modified example. This humidification duct 28 differs from the above-described embodiment in that in addition to first soundproof sheet 51 provided on the surface constituting the outer surface of humidification duct 28 on first surface 62a of flat portion 62, this humidification duct 28 has second soundproof sheet 52.

[0065] The second soundproof sheet 52 may be disposed at a first location P1 on the surface that constitutes the outer surface of the humidification duct 28 on the second surface 62b.

[0066] Alternatively, the second soundproof sheet 52 may be disposed at a second disposition location P2 on the surface that constitutes the inner surface of the humidification duct 28 on the first surface 62a.

[0067] 12 shows a configuration in which the second soundproof sheet 52 is disposed at both the first arrangement location P1 and the second arrangement location P2. Alternatively, the second soundproof sheet 52 may be disposed at only one of the first arrangement location P1 or the second arrangement location P2.

[0068] According to this configuration, the vibration of the duct is also damped by the second soundproof sheet, therefore, noise is further effectively reduced.

[0069] (6-2) Second Modification 13 shows a humidification duct 28 according to a second modified example. This humidification duct 28 differs from the above-described embodiment in that the recess 65 and the soundproof sheet 51 have an elliptical shape.

[0070] The longitudinal direction of the flattened portion 62 is the flattened longitudinal direction FL. Similarly, the longitudinal direction of the soundproof sheet 51 is the flattened longitudinal direction FL. That is, the flattened portion 62 and the soundproof sheet 51 share the same longitudinal direction.

[0071] According to this configuration, the area where the flat portion 62 and the soundproof sheet 51 overlap is large, so that noise can be reduced more effectively.

[0072] (6-3) Third Modification 14 shows a humidification duct 28 according to a third modified example. This humidification duct 28 differs from the above-described embodiment in that the shape of the recess 65 and the soundproof sheet 51 are rectangular. The flattened portion 62 and the soundproof sheet 51 share the flattened longitudinal direction FL. The recess 65 has a first side 65a on the upstream side and a second side 65b on the downstream side that are spaced apart in the direction of movement of the humidified air.

[0073] Fig. 15 is a cross-sectional view of the flat portion 62. A fillet F, which is a curved chamfer, is applied to the first side 65a and the second side 65b. Alternatively, the first side 65a and the second side 65b may be provided with a chamfer C, which is a flat chamfer, as shown in Fig. 16.

[0074] With this configuration, there are fewer portions that form acute angles on the inner surface of humidification duct 28 with which the airflow comes into contact, which makes the airflow move more smoothly and thus reduces vibration of humidification duct 28.

[0075] (6-4) Fourth Modification 17 shows a humidification duct 28 according to a fourth modified example. This humidification duct 28 differs from the above-described embodiment in that the shapes of the recess 65 and the soundproof sheet 51 are square.

[0076] <Conclusion> Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure described in the claims. [Explanation of symbols]

[0077] 10: Outdoor unit 20: Indoor unit 21: Casing 21L: Left side (side) 21R: Right side 21a: Inlet 21b: Air outlet 28: Humidification duct (duct) 28a: Humidified air outlet 28c: Humidified air intake 30: Humidification unit 40: Interconnecting piping group 41: Liquid connection pipe 42: Gas connection pipe 45: Air hose 48: Humidification communication line 49: Internal and external communication line 51: Soundproof sheet (first soundproof sheet) 52: Second soundproof sheet 61: Development section 62: Flat part 62a: 1st page 62b: 2nd side 63: Receptor 65: Recess 65a: Side 1 65b: Side 2 66: Base 100: Air conditioning equipment C: Chamfer CL: Casing longitudinal direction D: Depth EL: Left edge ER:Right end F: Fillet (chamfer) FL: Flat longitudinal direction (longitudinal direction) [Prior art documents] [Patent documents]

[0078] [Patent Document 1] JP 2023-024124 A

Claims

1. A casing (21); A duct (28) for introducing outdoor air into the casing or for sending air in the casing to the outdoors; A first soundproof sheet (51) installed in a recess (65) provided on the outer surface of the duct; The indoor unit (20) comprises:

2. The shape of the recess is substantially the same as the outer shape of the first soundproof sheet. The indoor unit according to claim 1.

3. The duct has a flattened portion (62) where the cross-sectional area of ​​the air flow path is small, The flat portion extends parallel to a side surface (21L) of the casing, The recess is provided on the outer surface of the flat portion. The indoor unit according to claim 1.

4. The flat portion and the first soundproof sheet share a longitudinal direction (FL), The indoor unit according to claim 3.

5. The flat portion has a first surface (62a) facing the side surface of the casing and a second surface (62b) parallel to the first surface, The recess is provided on the first surface. The indoor unit according to claim 3.

6. An area ratio of the recess to the first surface of the flat portion is 50% or more. The indoor unit according to claim 5.

7. A second soundproof sheet (52) is provided on at least one of the outside of the duct on the second surface and the inside of the duct on the first surface. The indoor unit according to claim 5.

8. The recess has an upstream first side (65a) and a downstream second side (65b) spaced apart in a direction of air flow through the duct, At least one of the first side and the second side is provided with a flat or curved chamfer (C, F). An indoor unit according to any one of claims 1 to 7.

9. The first soundproof sheet is rectangular, square, circular, or elliptical. The indoor unit according to claim 3.

10. The depth (D) of the recess is 4 mm or less. An indoor unit according to any one of claims 1 to 7.

11. An indoor unit (20) according to any one of claims 1 to 7, An air conditioning device (100).

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