JP7535702B2 - Indoor unit - Google Patents

Description

This disclosure relates to an indoor unit.

Cited Document 1 discloses a technology that includes a housing, an indoor heat exchanger housed inside the housing, a drain pan arranged below the indoor heat exchanger, and a refrigerant leakage sensor inside the housing that detects the refrigerant leaking from the indoor heat exchanger, the inside of the housing includes a sensor arrangement space on one side of the drain pan in which the refrigerant leakage sensor is arranged, and a non-sensor arrangement space on the other side of the drain pan in which the refrigerant leakage sensor is not arranged, and the inside of the housing includes a leaked refrigerant circulation path that connects the sensor arrangement space and the non-sensor arrangement space and circulates the refrigerant. Furthermore, when the refrigerant flows into the non-sensor arrangement space, the refrigerant leaking in the non-sensor arrangement space can also be detected by circulating the refrigerant from the through hole into the sensor arrangement space.

JP 2019-045006 A

This disclosure provides an indoor unit that can detect refrigerant leakage even when the amount of leaking refrigerant is small.

The present disclosure provides a refrigerant detection flow path that passes leaked refrigerant, and a refrigerant leakage sensor that detects the refrigerant, the refrigerant detection flow path including a main flow path that communicates with at least one of a header region having a piping connection portion that is connected to an external refrigerant piping of the heat exchanger or a header region that is not connected to the external refrigerant piping of the heat exchanger, and a branch flow path that branches off from the main flow path and communicates with a space having a lower pressure than the header region when the centrifugal fan is rotating, the refrigerant leakage sensor is installed in the branch flow path including an intersection of the main flow path and the branch flow path, and the refrigerant detection flow path is located on the underside of the drain pan .

According to the present disclosure, the vicinity of the suction port that draws in indoor air is under negative pressure, so if refrigerant leaks in the header area, the tip of the branch flow path becomes under negative pressure, and the refrigerant leaked from the refrigerant detection flow path can be sucked in and guided to the refrigerant leakage sensor. Therefore, even if the amount of leaking refrigerant is small, the refrigerant leakage sensor can detect the refrigerant leakage.

FIG. 1 is a side cross-sectional view showing an indoor unit according to a first embodiment. FIG. 1 is a plan view showing an indoor unit according to a first embodiment, as viewed from below. FIG. 1 is a schematic diagram showing an example of a refrigerant detection flow path according to a first embodiment; FIG. 4 is a schematic diagram showing another example of the refrigerant detection flow path according to the first embodiment; FIG. 4 is a schematic diagram showing another example of the refrigerant detection flow path according to the first embodiment; FIG. 13 is an explanatory diagram showing the wind speed distribution near the suction port in the first embodiment.

(Knowledge and other information that forms the basis of this disclosure)
At the time the inventors came up with the idea of this disclosure, there was a technology in which an indoor unit of an air conditioning apparatus was equipped with a refrigerant leakage sensor inside a housing that detected refrigerant leaking from an indoor heat exchanger, and the inside of the housing had a sensor arrangement space on one side of a drain pan in which the refrigerant leakage sensor was arranged, and a non-sensor arrangement space on the other side of the drain pan in which the refrigerant leakage sensor was not arranged, and a leaked refrigerant circulation path was provided inside the housing that connected the sensor arrangement space and the non-sensor arrangement space to allow the refrigerant to circulate.

In conventional technology, the sensor placement space and the non-sensor placement space are installed in places where no pressure difference occurs, even within the same housing. Therefore, if refrigerant leaks in the non-sensor placement space, the leaked refrigerant flows into the refrigerant detection flow path, and flows into the sensor placement space by natural diffusion, so the inventors discovered a problem that a certain amount of refrigerant must leak in order for the refrigerant leakage sensor to detect the refrigerant leakage. In order to solve this problem, the inventors came up with the subject matter of the present disclosure.
In view of this, the present disclosure provides an indoor unit that is capable of detecting refrigerant leakage even when the amount of leaking refrigerant is small.

Hereinafter, the embodiments will be described in detail with reference to the drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming more redundant than necessary and to facilitate understanding by those skilled in the art.
It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
Fig. 1 is a cross-sectional view showing the internal structure of an indoor unit of an air conditioner according to an embodiment of the present invention, Fig. 2 is a plan view of the indoor unit as viewed from below.

[1-1. Configuration]
1 and 2, the indoor unit 1 is installed on the ceiling of a building. The indoor unit 1 includes a box-shaped housing 10 and a decorative panel (not shown) that covers a lower opening of the housing 10.
The housing 10 has therein an insulating member 11 made of polystyrene foam, a heat exchanger 12, a blower 13, a drain pan 14 for receiving drain water from the heat exchanger 12, and a bell mouth 15 for straightening the air sucked into the blower 13.

The blower 13 is configured to include a fan motor 20 and a centrifugal fan 21. The fan motor 20 includes a rotating shaft 22 extending downward, and the centrifugal fan 21 is fixed to the rotating shaft 22.
The centrifugal fan 21 includes a disk-shaped main plate 23 fixed to a rotating shaft 22, an annular shroud 24 disposed below the main plate 23 and substantially coaxially with the main plate 23, and a plurality of blades 25 connecting the shroud 24 to the main plate 23. The plurality of blades 25 are disposed at intervals from one another in the circumferential direction of the main plate 23.

A heat exchanger 12 is disposed on each side of the housing 10. The heat exchanger 12 extends along the longitudinal direction of the housing 10.
An indoor air inlet 16 is provided in the center of the housing 10. Air outlets 17 are provided on both sides of the housing 10 and outside the heat exchangers 12.
Each air outlet 17 is provided with a flap (not shown) that can adjust the air outlet direction.
The fan motor 20 is driven to rotate the centrifugal fan 21, thereby drawing in indoor air from the suction port 16, passing the drawn air through the heat exchanger 12 for heat exchange, and then blowing the air out from the air outlet 17.

The drain pan 14 is placed below the heat exchanger 12 so that it can receive the drain water generated in the heat exchanger 12. The drain pan 14 is made of polystyrene foam.

In addition, in this embodiment, a header portion 31 to which the refrigerant piping 30 is folded back and connected, and a piping connection portion 33 to be connected to an external refrigerant piping 32 of an outdoor unit (not shown) are provided at both ends of the heat exchanger 12.
The region in which the header portion 31 and the pipe connection portion 33 are provided is defined as a header region 34 .
In this embodiment, four header regions 34 are provided at both ends of each of the two heat exchangers 12 .

A main flow passage 41 extending in the longitudinal direction of the heat exchanger 12 is provided on the lower surface side of the drain pan 14. The main flow passage 41 is disposed so as to extend in the longitudinal direction of the heat exchanger 12.
Both ends of the main flow passage 41 are connected to communication flow passages 42 that are bent upward so as to penetrate the drain pan 14. The communication flow passages 42 form part of the main flow passage 41.
The tip of the communication flow passage 42 is configured to open into the header region 34 .
The main flow path 41 includes a branch flow path 43 that branches off midway. The branch flow path 43 passes through the drain pan 14 from below, and is configured so that its discharge port opens into a space where the pressure is lower than that of the header region 34 when the centrifugal fan 21 rotates. Specifically, the discharge port of the branch flow path 43 is configured so as to open into a space downstream of the suction port 16.
The refrigerant detection flow path 40 is made up of the main flow path 41, the communication flow path 42, the branch flow path 43, and a connection flow path 44 (described later). The inner diameter of the refrigerant detection flow path 40 is preferably 11.5 mm or more.

It is preferable that the inner diameter of the refrigerant detection channel 40 satisfies the following formula.
ΔP=λ・L/D・γv
λ=64/Re
Re = Dv / v
Where:
L: Tube length (1.5)
D: Tube diameter γ: Density (1205 kg/m3)
v: flow velocity (0.15 m/s (= 1.5 m within 10 seconds))
ν: Kinematic viscosity (1.512×10^-5m2/s)
ΔP: Pressure loss (1 Pa (approximately 30 Pa at maximum wind speed)) = differential pressure.
According to the above formula, D is 11.5 mm, and it is seen that the inner diameter of the refrigerant detection channel 40 is preferably 11.5 mm or more.

A box-shaped sensor housing portion 45 is provided at the intersection of the refrigerant suction passage and the branch passage 43. A refrigerant leakage sensor 46 is housed inside the sensor housing portion 45.
It is preferable to install the refrigerant leakage sensor 46 so that its detection portion faces sideways or downward. By installing the refrigerant leakage sensor 46 in this manner, it is possible to prevent dust and the like from adhering to the refrigerant leakage sensor 46.
The tips of the communicating flow passage 42 and the branch flow passage 43 protrude upward from the upper surface of the drain pan 14. More specifically, the tips of the communicating flow passage 42 and the branch flow passage 43 are configured to be located above the water level of the drain water accumulated in the drain pan 14. This makes it possible to prevent the drain water from flowing in from the tips of the communicating flow passage 42 and the branch flow passage 43.

In this case, the branch flow path 43 is provided closer to the header region 34 having the pipe connection 33 connected to the external refrigerant pipe 32 of the heat exchanger 12 than the midpoint of the main flow path 41. This is because the pipe connection 33 is a location where refrigerant leakage is relatively likely to occur, so by providing the branch flow path 43 at a position close to the header region 34 having the pipe connection 33 and providing a refrigerant leakage sensor 46 near the intersection of this branch flow path 43 and the main flow path 41, refrigerant leakage can be detected more quickly.

Furthermore, the pipe connection portion 33 connects the external refrigerant pipe 32 and the refrigerant pipe 30 of the heat exchanger by brazing. When the pipes are connected by brazing, minute holes may be formed in the joint. In such a case, a small amount of refrigerant continues to leak from the hole, which is called a slow leak. When a slow leak occurs, it takes time for the concentration of the leaking refrigerant to increase, which causes a problem that the refrigerant leak may not be detected promptly.
However, with the above configuration, a refrigerant leak can be detected more quickly when the refrigerant leaks from the pipe connection portion 33 than when the refrigerant leaks from the header portion 31. Therefore, even in the case of a slow leak, the leaking refrigerant can be detected quickly.

In addition, it is desirable to form the inner diameter of the main flow path 41 that communicates with the header region 34 on the side that is not connected to the external refrigerant piping 32 relative to the connection point of the branch flow path 43 so as to be thicker than the inner diameter of the main flow path 41 that communicates with the header region 34 on the side that is connected to the external refrigerant piping 32.
The branch flow path 43 is located on the header region 34 side having the piping connection portion 33 connected to the external refrigerant piping 32 of the heat exchanger 12, rather than the midpoint of the main flow path 41. Therefore, with the above-mentioned configuration, it becomes possible to detect refrigerant leakage in the header region 34 on the side to which the external refrigerant piping 32 is not connected in the same way as detecting refrigerant leakage in the header region 34 on the side to which the external refrigerant piping 32 is connected.

3, the refrigerant detection flow path 40 includes two main flow paths 41 extending along the two heat exchangers 12 and communication flow paths 42 connected to both ends of each main flow path 41, and each main flow path 41 is connected via a connection flow path 44 that constitutes a part of the main flow path 41. A branch flow path 43 is connected to the middle of the connection flow path 44, and a sensor housing portion 45 is provided at the intersection of the connection flow path 44 and the branch flow path 43.
That is, in this example, the communication flow passage 42 communicates with the four header regions 34 provided at both ends of each heat exchanger 12. Then, there are two flow passages that flow from the main flow passage 41 to the sensor accommodating portion 45.

4, the other refrigerant detection flow paths 40 include four communicating flow paths 42 that communicate with the four header regions 34, and four main flow paths 41 that are connected to the respective communicating flow paths 42. The ends of the main flow paths 41 that are connected to the two communicating flow paths 42 on one side are connected by a connecting flow path 44, and the ends of the main flow paths 41 that are connected to the two communicating flow paths 42 on the other side are also connected by a connecting flow path 44. A sensor housing portion 45 that communicates with the two connecting flow paths 44 is provided in the middle of the two connecting flow paths 44.
That is, in this example, the communication flow passage 42 communicates with the four header regions 34 provided at both ends of each heat exchanger 12. Then, there are four flow passages flowing from the main flow passage 41 to the sensor accommodating portion 45.

Furthermore, as shown in FIG. 5 , the other refrigerant detection flow paths 40 include three communicating flow paths 42 that communicate with three of the four header regions 34, one main flow path 41 that is connected to two of the communicating flow paths 42, and a connecting flow path 44 that connects the other communicating flow path 42 and the main flow path 41.
In this case, it is desirable to provide the communication passage 42 in the header region 34 that has the pipe connection portion 33. This is because the pipe connection portion 33 is a location where refrigerant leakage is relatively likely to occur.
A sensor housing portion 45 is provided in the middle of the main flow path 41 .

[1-2. Action]
Next, the operation of this embodiment will be described.
By driving the fan motor 20 to rotate the centrifugal fan 21, indoor air is sucked in through the suction port 16. This air passes through the bell mouth 15 and is blown out by the centrifugal fan 21 to the outer periphery of the centrifugal fan 21. This air passes through the heat exchanger 12 and exchanges heat with the refrigerant in the heat exchanger 12, and is then blown out through the air outlet 17 into the room.

If a refrigerant leak occurs in the header region 34 of the heat exchanger 12 , the leaking refrigerant flows through the communication passage 42 and the main passage 41 into the sensor housing portion 45 .
When the refrigerant flows through the sensor housing portion 45, the refrigerant leakage sensor 46 can detect the leakage of the refrigerant.
At this time, when the centrifugal fan 21 rotates and draws in indoor air, negative pressure is created near the suction port 16 .

FIG. 6 is an explanatory diagram showing the wind speed distribution in the vicinity of the suction port 16. As shown in FIG.
As shown in FIG. 6 , it can be seen that the wind speed is high near the center of the suction port 16 and decreases toward the ends of the suction port 16 .
Therefore, in this embodiment, the tip of the branch flow path 43 opens into the downstream space near the center of the suction port 16, so that the tip of the branch flow path 43 becomes negative pressure, thereby sucking in the refrigerant that has leaked from the communicating flow path 42 and directing it to the sensor accommodating section 45 via the main flow path 41.

In this case, it is preferable that the discharge port of the branch flow path 43 of the refrigerant detection flow path 40 is provided at the location indicated by A in FIG.
Because the curved portion of the bellmouth 15 (indicated by B in FIG. 6 ) has a flow straightening function, it is not preferable to provide the outlet of the refrigerant detection flow path 40 at the curved portion B. Furthermore, the curved portion B of the bellmouth 15 is subject to greater vibrations due to air flow than the flat portion of the bellmouth 15 (indicated by C in FIG. 6 ). Providing an outlet of the refrigerant flow path in such a curved portion B may cause abnormal noise, so it is not preferable to provide the outlet of the refrigerant detection flow path 40 at the curved portion B.
6, the air speed slows down from the location indicated by A toward the +X direction (the end of the suction port 16), and the negative pressure weakens. Therefore, providing the discharge port of the refrigerant detection flow path 40 at the location indicated by A creates a larger pressure difference between the suction port (header region space) and the discharge port (suction space) of the refrigerant detection flow path 40 compared to providing the discharge port of the refrigerant detection flow path 40 in the planar region C. Therefore, providing the discharge port of the refrigerant detection flow path 40 at the location indicated by A allows the air in the header region 34 to flow more smoothly through the refrigerant detection flow path 40.

In addition, if a refrigerant leak occurs while the centrifugal fan 21 is stopped, the refrigerant will enter through the communication flow path 42 because it is heavier than air. This allows the leaked refrigerant to be sent to the sensor housing 45 even when the centrifugal fan 21 is stopped.

[1-3. Effects, etc.]
As described above, according to this embodiment, the system includes a heat exchanger 12 arranged within a housing 10, a drain pan 14 for receiving drain water from the heat exchanger 12, an inlet 16 for drawing in indoor air, an outlet 17 for blowing out the air after heat exchange into the room, a refrigerant detection flow path 40 through which leaked refrigerant passes, and a refrigerant leakage sensor 46 for detecting the refrigerant, the refrigerant detection flow path 40 includes a main flow path 41 communicating with at least one of a header region 34 having a piping connection portion 33 connected to the external refrigerant piping 32 of the heat exchanger 12 or a header region 34 not connected to the external refrigerant piping 32 of the heat exchanger 12, and a branch flow path 43 branching from the main flow path 41 and communicating with the space around the inlet 16, and the refrigerant leakage sensor 46 is installed in the branch flow path 43 including the intersection of the main flow path 41 and the branch flow path 43.
As a result, the vicinity of the suction port 16 that draws in indoor air is under negative pressure, so that if refrigerant leaks in the header region 34, the tip of the branch flow path 43 will be under negative pressure, and the refrigerant leaking from the refrigerant detection flow path 40 will be sucked in and led to the refrigerant leakage sensor 46. Therefore, even if the amount of leaking refrigerant is small, the refrigerant leakage sensor 46 can detect the refrigerant leakage.

Furthermore, according to this embodiment, the branch passage 43 is provided closer to the header region 34 having the pipe connection portion 33 connected to the external refrigerant pipe 32 of the heat exchanger 12 than the midpoint of the main passage 41 .
As a result, since the piping connection portion 33 is a location where refrigerant leakage is relatively likely to occur, by providing a branch flow path 43 at a position close to the header region 34 having the piping connection portion 33, refrigerant leakage can be detected more quickly by the refrigerant leakage sensor 46.

Furthermore, according to this embodiment, the refrigerant detection flow path 40 is disposed on the lower surface side of the drain pan 14 .
As a result, when the decorative panel is removed, the refrigerant detection flow path 40 is exposed, making it easy to inspect and maintain the refrigerant detection flow path 40.

In addition, according to this embodiment, the main flow path 41 and the branch flow path 43 are formed to penetrate the drain pan 14, and the ends of the main flow path 41 and the branch flow path 43 are located above the water level of the drain water accumulated in the drain pan 14.
This makes it possible to prevent drain water from flowing in from the tip end of the refrigerant detection flow passage 40.

Furthermore, according to this embodiment, two heat exchangers 12 are provided along both sides of the housing 10, and the air outlets 17 are provided on both sides of the housing 10.
This makes it possible to detect refrigerant leakage from indoor units 1 in which the air outlets 17, which are so-called two-way cassettes, are arranged on both sides of the housing 10.

In addition, according to this embodiment, two main flow paths 41 are provided along each heat exchanger 12, the refrigerant detection flow path 40 has a connecting flow path 44 that connects the two main flow paths 41, and the branch flow path 43 branches off from the connecting flow path 44.
This makes it possible to detect refrigerant leaking from the header regions 34 of the two heat exchangers 12.

The above-described embodiments are intended to illustrate the technology disclosed herein, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

As described above, when a refrigerant leak occurs in the header area of the heat exchanger, the air conditioner according to the present invention can use the negative pressure at the suction port to draw the leaked refrigerant into the refrigerant detection flow path, making it suitable for use in indoor units where the refrigerant detection sensor can detect a refrigerant leak even with a small amount of leaked refrigerant.

REFERENCE SIGNS LIST 1 Indoor unit 10 Housing 11 Thermal insulation member 12 Heat exchanger 13 Blower 14 Drain pan 15 Bell mouth 16 Intake port 17 Outlet 20 Fan motor 21 Centrifugal fan 22 Rotating shaft 23 Main plate 24 Shroud 25 Blade 30 Refrigerant piping 31 Header section 32 External refrigerant piping 33 Pipe connection section 34 Header region 40 Refrigerant detection flow path 41 Main flow path 42 Communication flow path 43 Branch flow path 44 Connection flow path 45 Sensor housing section 46 Refrigerant leakage sensor

Claims (5)

The cooling system includes a heat exchanger disposed in a housing, a centrifugal fan, a drain pan for receiving drain water from the heat exchanger, an intake port for drawing in indoor air, an outlet port for blowing out the air after heat exchange into the room, a refrigerant detection flow path for passing leaked refrigerant, and a refrigerant leakage sensor for detecting the refrigerant.
the refrigerant detection flow path includes a main flow path communicating with at least one of a header region having a piping connection portion connected to an external refrigerant piping of the heat exchanger and a header region not connected to the external refrigerant piping of the heat exchanger, and a branch flow path branching from the main flow path and communicating with a space having a lower pressure than the header region when the centrifugal fan is rotating,
The refrigerant leakage sensor is installed in the branch flow path including an intersection point of the main flow path and the branch flow path,
The indoor unit is characterized in that the refrigerant detection flow path is disposed on a lower surface side of the drain pan . The indoor unit according to claim 1, characterized in that the branch flow path is provided closer to the header area having a piping connection part connected to the external refrigerant piping of the heat exchanger than the midpoint of the main flow path. The main flow path and the branch flow path are formed by penetrating the drain pan,
3. The indoor unit according to claim 1 , wherein a tip end of the main flow path and a tip end of the branch flow path are located above a water level of drain water accumulated in the drain pan. The indoor unit according to any one of claims 1 to 3, wherein two of the heat exchangers are provided along both sides of the housing, and the air outlet is provided on both sides of the housing . The main flow passage is provided in two portions along each of the heat exchangers,
the refrigerant detection flow path includes a connection flow path that connects the two main flow paths,
The indoor unit according to claim 4 , wherein the branch flow path branches off from the connection flow path .

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