Indoor unit of air conditioner

Abstract

To provide an indoor unit of an air conditioner that can early detect a leaked refrigerant.SOLUTION: An indoor unit of an air conditioner according to the present disclosure uses a refrigerant having combustibility, and comprises: a heat exchanger for exchanging heat with indoor air; a case which has a back surface arranged so as to face a wall surface in a room, and comprises a lower surface covering at least a lower part of the heat exchanger; a refrigerant pipe connected to the heat exchanger, and in which the refrigerant is circulated; and a gas sensor arranged in the case, and detecting the refrigerant. A gap is provided between the back surface of the case and the wall surface. The lower surface of the case is provided with one or a plurality of holes penetrating to the outside from the inside of the case. The one or the plurality of holes have a larger dimension than a dimension of the gap in a direction toward a front surface of the case from the back surface. The gas sensor is arranged around the one or the plurality of holes in the lower surface of the case.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an indoor unit of an air conditioner. [Background technology]

[0002] To curb global warming, there is a demand for air conditioners to use refrigerants with low global warming potential (GWP). Many refrigerants with low GWP are flammable. For this reason, gas sensors that detect refrigerant leaks are sometimes installed in the indoor units of air conditioners.

[0003] For example, the indoor unit of the refrigeration device described in Patent Document 1 is provided with a refrigerant gas sensor that can detect refrigerant gas below the bottom surface of the casing or above the top surface of the casing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-173249 Summary of the Invention [Problem to be solved by the invention]

[0005] The indoor unit of the refrigeration system described in Patent Document 1 still has room for improvement in terms of early detection of leaking refrigerant.

[0006] The present disclosure provides an indoor unit of an air conditioner that is capable of detecting refrigerant leakage at an early stage. [Means for solving the problem]

[0007] An indoor unit of an air conditioner according to one aspect of the present disclosure includes: An indoor unit of an air conditioner that uses a flammable refrigerant, a heat exchanger that exchanges heat with indoor air; a housing having a back surface facing a wall surface of the room and a bottom surface covering at least a lower portion of the heat exchanger; a refrigerant pipe connected to the heat exchanger and through which a refrigerant circulates; a gas sensor disposed in the housing to detect a refrigerant; Equipped with a gap is provided between the rear surface of the housing and the wall surface; The lower surface of the housing is provided with one or more holes penetrating from the inside to the outside of the housing, the one or more holes have a dimension greater than a dimension of the gap in a direction from the rear surface toward the front surface of the housing; The gas sensor is disposed around the one or more holes on the lower surface of the housing. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an indoor unit of an air conditioner that is capable of detecting refrigerant leakage at an early stage. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view schematically illustrating the appearance of an indoor unit of an air conditioner according to the present disclosure. [Figure 2] Cross section AA of Figure 1 [Figure 3] FIG. 4 is a diagram schematically illustrating the rear of the indoor unit of FIG. 3. [Figure 4] FIG. 4 is a diagram schematically illustrating the rear surface K of the indoor unit of FIG. [Figure 5] Schematic diagram showing the arrangement of holes and gas sensors [Figure 6] Bottom view of the indoor unit in Figure 1 [Figure 7] Enlarged view of the hole [Figure 8] FIG. 10 is a perspective view schematically showing the rear surface of the indoor unit according to the first modification of the first embodiment. [Figure 9] Diagram showing the arrangement of holes and gas sensors in Figure 8 [Figure 10]FIG. 10 is a perspective view schematically showing the rear surface of the indoor unit according to the second embodiment. [Figure 11] 11 is a schematic diagram showing the arrangement relationship between the hole and the gas sensor in the indoor unit of FIG. [Figure 12] FIG. 10 is a diagram schematically illustrating the rear surface of the indoor unit according to the third embodiment. [Figure 13] 10 is a bottom view of an indoor unit according to a fourth embodiment. [Figure 14] A diagram emphasizing the gap SP between the indoor unit and the wall surface in Figure 13 [Figure 15] Enlarged view of the hole in the indoor unit in Figure 13 DETAILED DESCRIPTION OF THE INVENTION

[0010] (Background to this disclosure) In air conditioners, refrigerants such as R410A or R32 are widely used. However, from the perspective of preventing global warming, there is a demand for the use of refrigerants with a lower global warming potential (GWP).

[0011] Many refrigerants with low GWP contain flammable compounds. For this reason, there is a need for early detection of refrigerant leaks, for example, in the indoor unit of an air conditioner.

[0012] For example, the indoor unit of the refrigeration system described in Patent Document 1 is equipped with a refrigerant gas sensor. However, in Patent Document 1, the refrigerant gas is detected below the bottom surface of the casing or above the top surface of the casing, which makes it difficult to detect refrigerant leakage early. In addition, the indoor unit of the refrigeration system described in Patent Document 1 is equipped with a sensor lifting mechanism that moves the refrigerant gas sensor up and down, which increases the risk of failure of the lifting mechanism.

[0013] Therefore, the present inventors have studied an indoor unit of an air conditioner that is capable of early detection of refrigerant, and have arrived at the following invention.

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each drawing, elements are exaggerated for ease of explanation.

[0015] In this specification, terms such as "first" and "second" are used for descriptive purposes only and should not be understood as expressing or implying the relative importance or ranking of technical features. Features qualified as "first" and "second" expressly or imply the inclusion of one or more of the feature. In addition, in the accompanying drawings, the X, Y, and Z directions in the drawings respectively indicate the width, depth, and up / down directions of the indoor unit of the air conditioner.

[0016] (Embodiment 1) [Overall configuration] Fig. 1 is a perspective view schematically showing the appearance of an indoor unit 1 of an air conditioner of the present disclosure. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Fig. 3 is a perspective view schematically showing the back surface BK of the indoor unit 1 in Fig. 1. Fig. 4 is a diagram schematically showing the back surface BK of the indoor unit 1 in Fig. 3. The indoor unit 1 will be described with reference to Figs. 1 to 4.

[0017] The indoor unit 1 is an indoor unit of a home air conditioner. As shown in FIGS. 1 to 4, the indoor unit 1 includes a heat exchanger 10, a housing 20, refrigerant piping 30, and a gas sensor 40.

[0018] The heat exchanger 10, the refrigerant pipe 30, and the gas sensor 40 are disposed inside the housing 20. In this embodiment, a fan 50 for sending air into the room is disposed inside the housing 20.

[0019] The heat exchanger 10 exchanges heat with the air in the room where the indoor unit 1 is placed. As shown in Fig. 2, in this embodiment, the heat exchanger 10 is arranged inside the housing 20 so as to cover the front and top of the fan 50. In the indoor unit 1, the fan 50 takes in indoor air from the top of the housing 20 into the housing 20, and discharges the air that has exchanged heat in the heat exchanger 10 forward from the bottom of the housing 20, thereby adjusting the temperature of the indoor air.

[0020] As shown in FIG. 4, refrigerant piping 30 through which a refrigerant circulates is connected to the heat exchanger 10. In this embodiment, the refrigerant piping 30 includes a plurality of heat transfer tubes 31, a plurality of first bend tubes 32, and a plurality of second bend tubes 33. The plurality of heat transfer tubes 31 are arranged inside the housing 20 along the width direction (X direction) of the indoor unit 1. The plurality of first bend tubes 32 connect one end portions 31a of the plurality of heat transfer tubes 31 to each other. The plurality of second bend tubes 33 connect the other end portions 31b of the plurality of heat transfer tubes 31 to each other. The plurality of first bend tubes 32 and the plurality of second bend tubes 33 are components that connect the plurality of heat transfer tubes 31. Furthermore, the plurality of first bend tubes 32 and the plurality of second bend tubes 33 each have a curved shape, for example, a U-shape.

[0021] One end portion 31a of each of the plurality of heat transfer tubes 31 is connected to the plurality of first bend tubes 32 by, for example, brazing. Similarly, the other end portion 31b of each of the plurality of heat transfer tubes 31 is connected to the plurality of second bend tubes 33 by, for example, brazing.

[0022] In this embodiment, a flammable refrigerant such as propane (R290), isobutane (R600a), or ethane (R170) is used as the refrigerant. A flammable refrigerant is a refrigerant of a single composition or a mixed composition that includes at least one of a highly flammable refrigerant, a weakly flammable refrigerant, or a slightly flammable refrigerant. In this embodiment, a refrigerant with a global warming potential of 1500 or less can be used. In this embodiment, a refrigerant that is heavier than air is used as the refrigerant.

[0023] The housing 20 has a bottom surface 21 that covers at least the lower part of the heat exchanger 10. In this embodiment, the housing 20 covers both ends of the heat exchanger 10, the front of the heat exchanger 10, and the top of the heat exchanger 10. On the other hand, the back surface BK side of the housing 20 faces the wall surface WA, and therefore does not need to be covered. In this embodiment, at least the vicinity of the bottom surface 21 on the back surface BK side of the housing 20 is not covered. The housing 20 is formed in a substantially rectangular parallelepiped shape extending in the width direction (X direction). The housing 20 is placed with the back surface BK facing the wall surface WA inside the room.

[0024] As shown in Fig. 2, the indoor unit 1 is placed on a wall surface WA inside the room so that a gap SP is provided between the back surface BK of the housing 20 and the wall surface WA. The indoor unit 1 is attached to the wall surface WA, for example, via a frame 60. At this time, a gap SP of a predetermined dimension D1 is provided between the back surface BK of the housing 20 and the wall surface WA in the depth direction (Y direction) of the indoor unit 1, that is, in the direction from the back surface BK to the front surface FR of the housing 20. Because the lower part of the back surface BK of the housing 20 is not covered, the inside and outside of the housing 20 are connected via the gap SP.

[0025] The lower surface 21 of the housing 20 is provided with one or more holes 22 penetrating from the inside to the outside of the housing 20. In this embodiment, as shown in Figs. 3 and 4, one hole 22 is provided in the lower surface 21 of the housing 20. The hole 22 has a dimension in the depth direction (Y direction) of the indoor unit 1 that is larger than the dimension D1 of the gap SP.

[0026] 4, in the present embodiment, the holes 22 are provided in the underside 21 of the housing 20 at positions closer to the plurality of first bend pipes 32 than to the center in the width direction of the heat exchanger 10. In addition, in the present embodiment, the holes 22 are provided in the underside 21 of the housing 20 at positions that overlap with the portions where the plurality of first bend pipes 32 are arranged when the housing 20 is viewed from below. The shape and dimensions of the holes 22 will be described in detail later.

[0027] The gas sensor 40 is a sensor that is disposed in the housing 20 and detects the refrigerant. The gas sensor 40 is a sensor that can detect, for example, the concentration of the refrigerant in the air.

[0028] FIG. 5 is a diagram schematically illustrating the arrangement of the hole 22 and the gas sensor 40. The gas sensor 40 is arranged around the hole 22 on the underside 21 of the housing 20. Arranging around the hole 22 means that the gas sensor 40 is arranged along the inner circumferential surface that defines the hole 22. More specifically, as shown in FIG. 5, the gas sensor 40 is arranged so that at least a portion of the gas sensor 40 overlaps an area R1 that is within a predetermined distance from the inner circumferential surface of the hole 22 in the XY plane. The predetermined distance range is, for example, a range within 10 mm from the inner circumferential surface of the hole 22 in the XY plane. In other words, the gas sensor 40 is arranged so that the distance from the hole 22 does not exceed 10 mm. In this embodiment, the gas sensor 40 is arranged inside the housing 20 so as to be adjacent to the hole 22 in the width direction.

[0029] Of the refrigerant piping 30, the plurality of first bend pipes 32 and the plurality of second bend pipes 33 are each connected to the plurality of heat transfer pipes 31 by, for example, brazing. It is known that brazed portions are more susceptible to refrigerant leakage than other portions of the refrigerant piping 30. If refrigerant leaks from the bend pipes 32, 33, the refrigerant will flow from the portion where the bend pipes 32, 33 are located toward the underside 21 of the housing 20 because the refrigerant is heavier than air. Therefore, by providing a hole 22 in the underside 21 of the housing 20, the leaked refrigerant can be discharged from the hole 22 to the outside of the housing 20. In this case, by disposing a gas sensor 40 around the hole 22, the leaked refrigerant can be detected more quickly.

[0030] Next, a detailed description will be given of the hole 22 provided in the housing 20. Fig. 6 is a view of the indoor unit 1 of Fig. 1 as seen from below. Fig. 7 is an enlarged view of the hole 22.

[0031] As described above, the indoor unit 1 is disposed on the wall surface WA of the room so that a gap SP is provided between the rear surface BK of the housing 20 and the wall surface WA. As shown in FIG. 6 , when the indoor unit 1 is viewed from below, a long, narrow gap SP is formed between the housing 20 and the wall surface WA in the width direction (X direction). The size of the gap SP is determined by the width W1 of the housing 20 and the dimension D1 between the rear surface BK of the housing 20 and the wall surface WA. In this embodiment, for example, the width W1 of the housing 20 is 900 mm, and the dimension D1 between the rear surface BK of the housing 20 and the wall surface WA is 1 mm. The width W1 of the housing 20 may be, for example, 750 mm or more and 1050 mm or less, and the dimension D1 between the rear surface BK and the wall surface WA may be 0.5 mm or more and 2 mm or less.

[0032] As shown in FIG. 7, hole 22 has an elongated shape with its longitudinal direction extending in, for example, the depth direction (Y direction), and the longitudinal ends of hole 22 are formed in a rounded shape. In this embodiment, hole 22 is formed so that a dimension D2 of hole 22 in the depth direction is larger than a dimension D1 between the rear surface BK of housing 20 and wall surface WA. In this embodiment, for example, dimension D2 of hole 22 in the depth direction is 40 mm, and dimension W2 of hole 22 in the width direction is 10 mm. Dimension D2 of hole 22 in the depth direction may be, for example, 15 mm or more and 60 mm or less, and dimension W2 of hole 22 in the width direction may be, for example, 5 mm or more and 20 mm or less. Therefore, in the depth direction, hole 22 has dimension D2 that is larger than dimension D1 of gap SP.

[0033] Because refrigerant leaking inside the housing 20 is heavier than air, it moves toward the bottom surface 21 of the housing 20. Because a gap SP is provided between the back surface BK and the wall surface WA of the housing 20, the refrigerant flows along the bottom surface 21 of the housing 20 toward the gap SP and is discharged to the outside of the housing 20 through the gap SP. In this embodiment, a hole 22 is provided in the bottom surface 21 of the housing 20. The provision of the hole 22 in the bottom surface 21 of the housing 20 forms a flow path from the inside to the outside of the housing 20 between the location of the refrigerant leakage and the gap SP, allowing more of the leaked refrigerant to flow through the hole 22 than through the gap SP. The dimension of the hole 22 in the depth direction is greater than the distance D1 between the back surface BK and the wall surface WA of the housing 20, allowing more refrigerant to flow into the hole 22. By allowing more of the leaked refrigerant to flow through the hole 22 than through the gap SP, the leaked refrigerant can be detected more quickly by the gas sensor 40 disposed around the hole 22.

[0034] [effect] According to the above-described embodiment, the following effects can be achieved.

[0035] The indoor unit 1 according to this embodiment is an indoor unit for an air conditioner that uses a flammable refrigerant. The indoor unit 1 includes a heat exchanger 10, a housing 20, refrigerant piping 30, and a gas sensor 40. The heat exchanger 10 exchanges heat with indoor air. The housing 20 is disposed with its back surface (BK) facing a wall surface (WA) of the room and has a bottom surface (21) that covers at least the lower part of the heat exchanger 10. The refrigerant piping 30 is connected to the heat exchanger 10 and circulates the refrigerant. The gas sensor 40 is disposed in the housing 20 and detects the refrigerant. A gap (SP) is provided between the back surface (BK) of the housing 20 and the wall surface (WA). The bottom surface (21) of the housing 20 is provided with a hole (22) that penetrates from the inside to the outside of the housing 20. The hole (22) has a dimension (D2) that is larger than the dimension (D1) of the gap (SP) in the direction from the back surface (BK) toward the front surface (FR) of the housing 20. The gas sensor 40 is disposed around the hole (22) on the bottom surface (21) of the housing 20.

[0036] With this configuration, it is possible to provide an indoor unit of an air conditioner that is capable of detecting refrigerant leakage at an early stage.

[0037] The refrigerant piping 30 includes a plurality of heat transfer tubes 31 arranged in the housing 20, a plurality of first bend tubes 32 connecting one ends 31a of the plurality of heat transfer tubes 31 together, and a second bend tube 33 connecting the other ends 31b of the plurality of heat transfer tubes 31 together. The hole 22 may be located closer to at least one of the plurality of first bend tubes 32 and the plurality of second bend tubes 33 than to the center of the heat exchanger 10.

[0038] With this configuration, the leaked refrigerant is more likely to be discharged to the outside of the housing 20 through the hole 22. This allows the gas sensor 40 to detect the leaked refrigerant at an earlier stage.

[0039] When the housing 20 is viewed from below, the hole 22 may be located at a position overlapping at least one of the portion where the multiple first bend pipes 32 are arranged or the portion where the multiple second bend pipes 33 are arranged.

[0040] With this configuration, leaked refrigerant can be easily discharged to the outside of the housing 20 through the hole 22. Therefore, the gas sensor 40 can detect leaked refrigerant at an early stage.

[0041] The gas sensor 40 may be disposed inside the housing 20 .

[0042] The gas sensor 40 may be positioned adjacent to the hole 22 .

[0043] With this configuration, the gas sensor 40 can detect refrigerant leakage at an early stage.

[0044] When the housing 20 is viewed from below, the hole 22 may have a shape whose longitudinal direction is in the direction from the rear surface BK to the front surface FR.

[0045] With this configuration, holes 22 can be provided in a shape that follows the flow of the leaked refrigerant, making it easier for the refrigerant to flow to holes 22.

[0046] The refrigerant may be a single-component refrigerant or a mixed-component refrigerant containing at least one of a highly flammable refrigerant, a weakly flammable refrigerant, and a slightly flammable refrigerant.

[0047] The refrigerant may have a global warming potential of 1500 or less.

[0048] With this configuration, it is possible to detect leakage of a refrigerant that is heavier than air and flammable.

[0049] In the above-described embodiment, an example has been described in which the gas sensor 40 is disposed adjacent to the hole 22 in the width direction, but this is not limiting. FIG. 8 is a perspective view schematically showing the rear surface BK of the indoor unit 1A according to Modification 1 of Embodiment 1. FIG. 9 is a diagram showing the arrangement of the hole 22 and the gas sensor 40 in FIG. 8. As shown in FIGS. 8 and 9, the gas sensor 40 may be disposed adjacent to the hole 22 in the depth direction. In the event of a refrigerant leak, most of the refrigerant flows from the front surface FR of the housing 20 toward the rear surface BK. Therefore, by disposing the gas sensor 40 on the rear surface BK side of the hole 22, it is possible to more easily detect the leaked refrigerant.

[0050] In the above-described embodiment, the hole 22 has a shape having a longitudinal direction extending from the back surface BK to the front surface FR of the housing 20, but is not limited to this. The hole 22 may have a longitudinal direction extending in the width direction (X direction) of the housing 20, for example, or may have an inner shape without a longitudinal direction, such as a square or circle.

[0051] In the above-described embodiment, the hole 22 is provided at a position closer to the first bend pipe 32 than the center of the heat exchanger 10, but the present invention is not limited to this. The hole 22 may be provided at a position closer to the second bend pipe 33 than the center of the heat exchanger 10. Alternatively, the hole 22 may be provided at any position on the lower surface 21 of the housing 20.

[0052] In the above-described embodiment, the hole 22 is provided at a position overlapping the portion where the first bend pipe 32 is disposed when the housing 20 is viewed from below, but the present invention is not limited to this. The hole 22 may be provided at a position overlapping the portion where the second bend pipe 33 is disposed.

[0053] (Embodiment 2) A second embodiment will be described with reference to Figures 10 and 11. In the second embodiment, the same or equivalent configurations as those in the first embodiment will be denoted by the same reference numerals. In the second embodiment, descriptions that overlap with those in the first embodiment will be omitted.

[0054] Fig. 10 is a perspective view schematically showing the back surface BK of the indoor unit 1B according to embodiment 2. Fig. 11 is a schematic diagram showing the positional relationship between the holes 22 and the gas sensor 40 in the indoor unit 1B of Fig. 10. As shown in Figs. 10 and 11, embodiment 2 differs from embodiment 1 in that a plurality of holes 22 are provided in the underside 21 of the housing 20.

[0055] In this embodiment, three holes 22 are provided in the lower surface 21 of the housing 20. The distance between the holes 22 is, for example, smaller than the width of the holes 22 in the width direction of the housing 20. The gas sensor 40 is disposed around the three holes 22. More specifically, as shown in FIG. 11 , the gas sensor 40 is disposed so that at least a portion of the gas sensor 40 overlaps with an area R2 that surrounds the three holes 22.

[0056] As in the first embodiment, each of the three holes 22 is provided at a position closer to the first bend pipe 32 than to the center of the heat exchanger 10.

[0057] By providing a plurality of holes 22 in the housing 20, a larger amount of refrigerant can flow through the holes 22, and the gas sensor 40 can detect the refrigerant at an early stage.

[0058] When a plurality of holes 22 are provided, some of the plurality of holes 22 may be provided at positions closer to the first bend pipe 32 than the center of the heat exchanger 10, and other portions of the plurality of holes 22 may be provided at positions closer to the second bend pipe 33 than the center of the heat exchanger 10. In other words, a plurality of holes 22 may be provided at a plurality of locations on the underside 21 of the housing 20.

[0059] Furthermore, when a plurality of holes 22 are provided, the gas sensor 40 may be disposed across the plurality of holes. Alternatively, when a plurality of holes 22 are provided, a plurality of gas sensors 40 may be disposed.

[0060] (Embodiment 3) Embodiment 3 will be described with reference to Fig. 12. In Embodiment 3, the same or equivalent configurations as in Embodiment 1 will be denoted by the same reference numerals. Also, in Embodiment 3, descriptions that overlap with Embodiment 1 will be omitted.

[0061] Fig. 12 is a diagram schematically showing the back surface BK of an indoor unit 1C according to embodiment 3. As shown in Fig. 12, the gas sensor 40 is disposed outside the housing 20, which is a difference from embodiment 1.

[0062] In this embodiment, the gas sensor 40 is disposed on the underside 21 of the housing 20 around the hole 22 and outside the housing 20. By disposing the gas sensor 40 outside the housing 20, the gas sensor 40 can detect the leaking refrigerant when it passes through the hole 22.

[0063] (Fourth embodiment) A fourth embodiment will be described with reference to Figures 13 to 15. In the fourth embodiment, the same or equivalent configurations as those in the first embodiment will be denoted by the same reference numerals. In the fourth embodiment, descriptions that overlap with those in the first embodiment will be omitted.

[0064] Fig. 13 is a view from below of an indoor unit 1D according to the fourth embodiment. Fig. 14 is a view emphasizing the gap SP between the indoor unit 1D of Fig. 13 and the wall surface WA. Fig. 15 is an enlarged view of the hole 22 of the indoor unit 1D of Fig. 13. The fourth embodiment differs from the first embodiment in that the hole 22 is defined based on the equivalent diameter of the hole 22 and the gap SP.

[0065] "Equivalent diameter" is the diameter of a circular channel equivalent to a channel of any cross-sectional shape. The equivalent diameter can be calculated based on the wetted perimeter length. The wetted perimeter length is the perimeter of the inner surface of the cross section of a tubular channel. When the wetted perimeter length of the channel is L and the cross-sectional area of ​​the channel is A, the equivalent diameter Deq can be calculated using the formula Deq = 4A / L.

[0066] The equivalent diameter of the gap SP can be calculated by assuming that the cross section of the gap SP is a rectangle with a width W1 and a depth D1. Therefore, the equivalent diameter of the gap SP can be calculated based on the width W1 of the housing 20 and the distance D1 between the wall surface WA and the housing 20. As shown in Fig. 14, although the gap SP is not surrounded by an inner peripheral surface, the length of the dashed arrow starting from point P1 can be taken as the wetted edge length of the gap SP, and therefore the wetted edge length L1 of the gap SP is L1 = 2 × W1 + 2 × D1.

[0067] The equivalent diameter of the hole 22 can be calculated based on the perimeter of the inner circumferential surface that defines the hole 22, i.e., the wetted perimeter length. As shown in Fig. 15, the wetted perimeter length L2 of the hole 22 is the length indicated by the dashed arrow starting from point P2.

[0068] The shape and dimensions of hole 22 are preferably set so that the equivalent diameter of hole 22 is between three and fifteen times the equivalent diameter of gap SP. Assuming that the flow resistance of hole 22 and gap SP is proportional to the fourth power of the equivalent diameter, when the diameter of hole 22 is three times the equivalent diameter of gap SP, the flow rate of the refrigerant passing through hole 22 and the flow rate of the refrigerant passing through gap SP will be approximately equal. The refrigerant flow rate indicates the ease of flow of the refrigerant through hole 22 or gap SP. If the ease of flow of the refrigerant through hole 22 is equal to or greater than the ease of flow of the refrigerant through gap SP, more of the leaked refrigerant can flow through hole 22. Therefore, the equivalent diameter of hole 22 is preferably three times or more the equivalent diameter of gap SP. Furthermore, considering the appearance of indoor unit 1D, the equivalent diameter of hole 22 is preferably 15 times or less the equivalent diameter of gap SP.

[0069] (Addendum) The above description of the embodiments discloses the following techniques.

[0070] (Technology 1) An indoor unit of an air conditioner that uses a flammable refrigerant, comprising: a heat exchanger that exchanges heat with indoor air; a housing that is arranged with its back facing a wall surface inside the room and has a bottom surface that covers at least the lower part of the heat exchanger; refrigerant piping that is connected to the heat exchanger and through which the refrigerant circulates; and a gas sensor that is arranged in the housing and detects the refrigerant; a gap is provided between the back surface of the housing and the wall surface; the bottom surface of the housing has one or more holes that penetrate from the inside to the outside of the housing, the one or more holes having a dimension larger than the dimension of the gap in the direction from the back surface toward the front surface of the housing; and the gas sensor is arranged around the one or more holes on the bottom surface of the housing.

[0071] With this configuration, it is possible to provide an indoor unit of an air conditioner that is capable of detecting refrigerant leakage at an early stage.

[0072] (Technology 2) In the indoor unit of the air conditioner described in Technology 1, the refrigerant piping has a plurality of heat transfer tubes arranged in a housing, a plurality of first bend tubes connecting one ends of the plurality of heat transfer tubes together, and a second bend tube connecting the other ends of the plurality of heat transfer tubes together, and the one or more holes are provided in a position closer to at least one of the plurality of first bend tubes or the plurality of second bend tubes than to the center of the heat exchanger.

[0073] This configuration allows leaking refrigerant to be more easily discharged to the outside of the housing through one or more holes, allowing the gas sensor to detect leaking refrigerant earlier.

[0074] (Technology 3) The indoor unit of the air conditioner described in Technology 2, wherein when the housing is viewed from below, the one or more holes are provided in a position that overlaps with at least one of the portion where the multiple first bend pipes are arranged or the portion where the multiple second bend pipes are arranged.

[0075] This configuration allows leaking refrigerant to be easily discharged to the outside of the housing through one or more holes, allowing the gas sensor to detect leaking refrigerant at an early stage.

[0076] (Technology 4) The indoor unit of the air conditioner according to any one of Technologies 1 to 3, wherein the gas sensor is disposed inside or outside the housing.

[0077] With this configuration, the gas sensor can detect refrigerant leakage at an early stage.

[0078] (Technology 5) The indoor unit of the air conditioner according to any one of Technologies 1 to 4, wherein the gas sensor is disposed adjacent to one or more holes.

[0079] With this configuration, the gas sensor can detect refrigerant leakage at an early stage.

[0080] (Technology 6) An indoor unit of an air conditioner described in any one of Technologies 1 to 5, wherein when the housing is viewed from below, one or more holes have a shape with a longitudinal direction from the back to the front.

[0081] With this configuration, one or more holes can be provided that have a shape that follows the flow of the leaked refrigerant, making it easier for the refrigerant to flow to the one or more holes.

[0082] (Technology 7) An indoor unit of an air conditioner described in any one of Technologies 1 to 6, wherein when the housing is viewed from below, each of the equivalent diameters of one or more holes calculated based on the perimeter of the inner surface defining the one or more holes is between 3 and 15 times the equivalent diameter of the gap calculated based on the width of the housing in the direction in which the housing extends along the wall surface and the distance between the wall surface and the housing.

[0083] This configuration allows the flow rate of the refrigerant flowing through the one or more holes to be faster than the flow rate of the refrigerant flowing through the gaps, thereby allowing more of the leaked refrigerant to flow through the one or more holes.

[0084] (Technology 8) An indoor unit of an air conditioner according to any one of Technologies 1 to 7, wherein the refrigerant is a single-composition refrigerant or a mixed-composition refrigerant containing at least one of a highly flammable refrigerant, a weakly flammable refrigerant, and a slightly flammable refrigerant.

[0085] With this configuration, it is possible to detect leakage of a refrigerant that is heavier than air and flammable.

[0086] (Technology 9) The indoor unit of the air conditioner according to any one of Technologies 1 to 8, wherein the refrigerant has a global warming potential of 1500 or less.

[0087] With this configuration, it is possible to detect leakage of a refrigerant that is heavier than air and flammable. [Industrial Applicability]

[0088] The present disclosure can be widely applied to air conditioners that use flammable refrigerants. [Explanation of symbols]

[0089] 1, 1A, 1B, 1C, 1D indoor unit 10 Heat exchanger 20 Case 21 Bottom side 22 holes 30 Refrigerant piping 31 Heat transfer tube 31a End 31b End 32 First bend pipe 33 Second Bend Pipe 40 Gas Sensor

Claims

1. An indoor unit of an air conditioner that uses a flammable refrigerant, a heat exchanger that exchanges heat with indoor air; a housing having a back surface facing a wall surface of the room and a bottom surface covering at least a lower portion of the heat exchanger; a refrigerant pipe connected to the heat exchanger and through which a refrigerant circulates; a gas sensor disposed in the housing to detect the refrigerant; Equipped with a gap is provided between the rear surface of the housing and the wall surface; The lower surface of the housing is provided with one or more holes penetrating from the inside to the outside of the housing, the one or more holes have a dimension greater than a dimension of the gap in a direction from the rear surface toward the front surface of the housing; the gas sensor is disposed around the one or more holes on the lower surface of the housing; Air conditioner indoor unit.

2. the refrigerant piping includes a plurality of heat transfer tubes arranged in the housing, a plurality of first bend tubes connecting one ends of the plurality of heat transfer tubes to each other, and a second bend tube connecting the other ends of the plurality of heat transfer tubes to each other, the one or more holes are provided at a position closer to at least one of the plurality of first bend pipes or the plurality of second bend pipes than to a center of the heat exchanger; An indoor unit for an air conditioner according to claim 1.

3. When viewed from below, the one or more holes are provided at positions overlapping at least one of a portion where the plurality of first bend pipes are arranged and a portion where the plurality of second bend pipes are arranged. The indoor unit of an air conditioner according to claim 2.

4. The gas sensor is disposed inside or outside the housing. An indoor unit for an air conditioner according to claim 1.

5. the gas sensor is positioned adjacent to the one or more holes. An indoor unit for an air conditioner according to claim 1.

6. When the housing is viewed from below, the one or more holes have a shape having a longitudinal direction extending from the rear surface to the front surface. An indoor unit for an air conditioner according to claim 1.

7. When the housing is viewed from below, each of the equivalent diameters of the one or more holes calculated based on the perimeter of an inner circumferential surface defining the one or more holes is 3 to 15 times the equivalent diameter of the gap calculated based on the width of the housing in the direction in which the housing extends along the wall surface and the distance between the wall surface and the housing. An indoor unit for an air conditioner according to claim 1.

8. The refrigerant is a single-component refrigerant or a mixed-component refrigerant containing at least one of a highly flammable refrigerant, a weakly flammable refrigerant, and a slightly flammable refrigerant. An indoor unit for an air conditioner according to claim 1.

9. The global warming potential of the refrigerant is 1500 or less. An indoor unit for an air conditioner according to claim 1.

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