JP7105538B2 - Indoor unit of air conditioner - Google Patents

Description

The present invention relates to an indoor unit of an air conditioner.

Refrigerant circulates in a refrigerant circuit that constitutes an air conditioner. Among the wide variety of substances used as refrigerants, some have toxic or suffocating properties in humans. Therefore, when the refrigerant leaks from the indoor unit, the fan may be controlled to rotate at high speed. The purpose of this control is to diffuse the leaked refrigerant into the room and reduce the concentration of the refrigerant, thereby minimizing the adverse health effects of the user. This control is also performed, for example, in a floor-standing air conditioner disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2016-070594).

In the air conditioner of Patent Literature 1, when the amount of refrigerant leakage increases further, control is also performed to stop the fan. The reason for this is that refrigerant heavier than air leaks from the outlets provided near the floor, so it is safer to concentrate the refrigerant near the floor rather than expanding the flammable concentration range by diffusion of the refrigerant. It is because of the recognition that there is On the other hand, in an air conditioner such as a wall-mounted type or a ceiling-embedded type that has an air outlet at a height apart from the floor surface, it is inevitable that the refrigerant moves a distance from the air outlet to the floor surface. In this case, the diffusion of the refrigerant due to the high-speed rotation of the fan is considered to be effective in ensuring the safety of the user, regardless of the amount of refrigerant leakage.

However, the high speed rotation of the fan causes noise. A user feels uncomfortable when a sudden loud noise is emitted from an indoor unit. Therefore, even when the refrigerant leaks, it is better not to control the fan to rotate at an excessive speed as much as possible.

SUMMARY OF THE INVENTION An object of the present invention is to reduce noise caused by fan rotation when refrigerant leaks from an air conditioner.

An indoor unit according to a first aspect of the present invention is for an air conditioner configured to form a refrigerant circuit for circulating refrigerant. The indoor unit includes a heat exchanger, a fan, a refrigerant leakage detector that detects the amount of refrigerant leaked from the refrigerant circuit, and a controller that controls the rotational speed of the fan. The control unit increases the rotation speed when the refrigerant leakage amount is greater than a predetermined threshold than when the refrigerant leakage amount is less than the threshold.

According to this configuration, the rotation speed of the fan increases when the refrigerant leakage amount is large, and the rotation speed of the fan decreases when the refrigerant leakage amount is small. Therefore, when there is an urgent need to deal with refrigerant leakage, the leaked refrigerant quickly diffuses into the room, reducing the concentration of the refrigerant. Suppressed.

An indoor unit according to a second aspect of the present invention is the indoor unit according to the first aspect, wherein the controller increases the rotation speed as the refrigerant leakage amount increases.

According to this configuration, the rotation speed of the fan increases as the refrigerant leakage amount increases. Therefore, an appropriate rotation speed is determined in consideration of the urgency of reducing the concentration of the refrigerant and suppressing the noise.

An indoor unit according to a third aspect of the present invention is the indoor unit according to the first aspect or the second aspect, wherein the refrigerant leakage detection section has a refrigerant concentration sensor. The refrigerant leakage amount is determined based on the concentration signal output from the refrigerant concentration sensor.

According to this configuration, the rotational speed of the fan is determined by the concentration signal output by the refrigerant concentration sensor. Therefore, the required air volume is determined based on the concentration of the leaked refrigerant, and the rotational speed of the fan is sufficient to generate the required air volume, so that unnecessary loud noise does not cause discomfort to the user. can be suppressed.

An indoor unit according to a fourth aspect of the present invention is the indoor unit according to any one of the first aspect to the third aspect, wherein the refrigerant leakage detection section detects the amount of refrigerant leakage in multiple stages.

According to this configuration, the refrigerant leakage amount is detected as multi-step values. Therefore, by determining the rotation speed in multiple stages according to the detection levels in multiple stages, it is possible to realize the rotation speed suitable for the amount of refrigerant leakage.

An indoor unit according to a fifth aspect of the present invention is the indoor unit according to any one of the first aspect to the fourth aspect, and is of the ceiling installation type or the wall installation type.

According to this configuration, the indoor unit is, for example, a ceiling-embedded type, a ceiling-suspended type, a wall-mounted type, or a wall-embedded type. Therefore, when the refrigerant leaks, the refrigerant falling from the ceiling or the wall can be diffused into the room and the concentration can be reduced.

An indoor unit according to a sixth aspect of the present invention is the indoor unit according to any one of the first aspect to the fourth aspect, which is a floor-mounted type installed on the floor. The indoor unit further includes a casing. The casing has an air outlet provided at a height spaced apart from the floor surface.

According to this configuration, the indoor unit is of a floor installation type, and has an outlet spaced apart from the floor surface. Therefore, the refrigerant coming down from the outlet can be diffused in the room and the concentration can be lowered.

According to the indoor units according to the first to fourth aspects of the present invention, the concentration reduction of the refrigerant and the suppression of noise are executed according to the degree of urgency.

According to the indoor unit according to the fifth aspect of the present invention, the concentration of refrigerant coming down from the ceiling or walls can be reduced.

According to the indoor unit according to the sixth aspect of the present invention, it is possible to reduce the concentration of the refrigerant coming down from the outlet spaced apart from the floor surface.

1 is a schematic diagram of an air conditioner 90 including an indoor unit 20 according to one embodiment of the present invention; FIG. 4 is a schematic diagram showing an installation state of the indoor unit 20. FIG. 3 is a block diagram showing the configuration of a coolant leakage detection unit 26; FIG. 4 is a graph showing processing characteristics of a coolant leakage detection unit 26; 4 is a graph showing processing characteristics of a coolant leakage detection unit 26; 4 is a graph showing processing characteristics of a coolant leakage detection unit 26; 4 is a graph showing processing characteristics of a coolant leakage detection unit 26; FIG. 5 is a schematic diagram showing the installation state of an indoor unit 20A according to Modification A of the present invention and an indoor unit 20B according to Modification B of the present invention. FIG. 11 is a block diagram showing a configuration of a refrigerant leakage detection section 26 of an indoor unit 20 according to Modification C of the present invention;

(1) Overall Configuration FIG. 1 shows an air conditioner 90 using an indoor unit 20 according to one embodiment of the present invention. The air conditioner 90 has a refrigerant circuit 80 that circulates a refrigerant to perform a refrigeration cycle. The refrigerant circuit 80 has an outdoor unit 10 , an indoor unit 20 and a connecting pipe 30 .

(2) Detailed configuration (2-1) Outdoor unit 10
The outdoor unit 10 functions as a cold heat source or a hot heat source, and is installed outdoors. The outdoor unit 10 includes a casing 11, a compressor 12, a four-way switching valve 13, an outdoor heat exchanger 14, a fan 15, an expansion valve 16, a liquid-side shut-off valve 17, a gas-side shut-off valve 18, a controller 19, and an inter-part It has piping that connects

(2-1-1) Casing 11
The casing 11 accommodates components of the outdoor unit 10 .

(2-1-2) Compressor 12
The compressor 12 compresses the low-pressure gas refrigerant and discharges high-pressure gas refrigerant. The compressor 12 has a suction port 12a and a discharge port 12b. Low-pressure gas refrigerant is sucked from the suction port 12a. The high-pressure gas refrigerant is discharged in the direction of arrow D from the discharge port 12b.

(2-1-3) Four-way switching valve 13
The four-way switching valve 13 switches between cooling operation and heating operation. When performing cooling operation, the four-way switching valve 13 is connected as indicated by the solid line in FIG. On the other hand, when performing the heating operation, the four-way switching valve 13 is connected as indicated by the dashed line in FIG.

(2-1-4) Outdoor heat exchanger 14
The outdoor heat exchanger 14 exchanges heat between the refrigerant and the outside air. The outdoor heat exchanger 14 functions as a radiator during cooling operation, and functions as a heat absorber during heating operation. The outdoor heat exchanger 14 may have a refrigerant flow distributor 14a. The refrigerant flow divider 14a serves to evenly send the low-pressure gas-liquid two-phase refrigerant to each part of the outdoor heat exchanger 14, for example, in heating operation.

(2-1-5) Fan 15
The fan 15 facilitates heat exchange between the refrigerant and the outside air by the outdoor heat exchanger 14 .

(2-1-6) Expansion valve 16
The expansion valve 16 is configured by a valve whose degree of opening is adjustable. The opening is adjusted electrically, for example. The expansion valve 16 reduces the pressure of the refrigerant as required or limits the amount of refrigerant passing through.

(2-1-7) Liquid-side shut-off valve 17, gas-side shut-off valve 18
The liquid-side shut-off valve 17 and the gas-side shut-off valve 18 are for opening or closing the refrigerant path. Opening and closing can be done manually, for example. The liquid-side shut-off valve 17 and the gas-side shut-off valve 18 are closed, for example, when the air conditioner 90 is installed, in order to prevent the refrigerant sealed in the outdoor unit 10 from leaking to the outside. On the other hand, the liquid-side shut-off valve 17 and the gas-side shut-off valve 18 are opened when the air conditioner 90 is in use.

(2-1-8) Control unit 19
The controller 19 receives output signals from various sensors provided in the outdoor unit 10 . These various sensors may include a temperature sensor or a pressure sensor (not shown). The controller 19 also drives the compressor 12, the four-way switching valve 13, the fan 15, the expansion valve 16, and other actuators (not shown).

(2-2) Connection pipe 30
The communication pipe 30 guides the refrigerant between the outdoor unit 10 and the indoor unit 20 . The communication pipe 30 has a liquid communication pipe 31 and a gas communication pipe 32 . The liquid communication pipe 31 is connected to the liquid side stop valve 17 . The gas communication pipe 32 is connected to the gas side shutoff valve 18 . The liquid connection pipe 31 mainly guides liquid refrigerant or gas-liquid two-phase refrigerant. The gas communication line 32 mainly guides the gas refrigerant.

(2-3) Indoor unit 20
The indoor unit 20 is provided in the user's room and generates cool air or warm air to make the room temperature comfortable. The indoor unit 20 has a casing 21, an indoor heat exchanger 22, a fan 23, and pipes 29a and 29b. The indoor unit 20 further has a control section 25 and a refrigerant leakage detection section 26 .

(2-3-1) Casing 21
The casing 21 accommodates components of the indoor unit 20 . As shown in FIG. 2, the indoor unit 20 is ceiling mounted and supplies conditioned air from above the room 50 to the user. The casing 21 is formed with an intake port 21a for sucking indoor air and an outlet port 21b for blowing air into the room. The casing 21 is configured to be embedded in the ceiling. Alternatively, casing 21 may be configured to be suspended from the ceiling.

(2-3-2) Indoor heat exchanger 22
Returning to FIG. 1, the indoor heat exchanger 22 exchanges heat between the refrigerant and the indoor air. The indoor heat exchanger 22 functions as a heat absorber during cooling operation, and functions as a radiator during heating operation. The indoor heat exchanger 22 may have a refrigerant flow divider 22a. The refrigerant flow divider 22a serves to evenly send the low-pressure gas-liquid two-phase refrigerant to each part of the indoor heat exchanger 22, for example, in cooling operation.

(2-3-3) Fan 23
The fan 23 facilitates heat exchange between the refrigerant and the indoor air by the indoor heat exchanger 22 . In addition, the fan 23 blows out the air that has finished heat exchange from the casing 21 and sends it to the indoor space.

(2-3-4) Piping 29a, 29b
The pipe 29 a connects the liquid communication pipe 31 and the indoor heat exchanger 22 . The pipe 29 a may be separate from the liquid communication pipe 31 and connected to the liquid communication pipe 31 or may be integrated with the liquid communication pipe 31 .

The pipe 29 b connects the gas communication pipe 32 and the indoor heat exchanger 22 . The pipe 29 b may be separate from the gas communication pipe 32 and may be connected to the gas communication pipe 32 or may be integrated with the gas communication pipe 32 .

(2-3-5) Refrigerant leakage detector 26
The refrigerant leakage detection unit 26 detects refrigerant leakage from the refrigerant circuit 80 . A configuration of the coolant leakage detection unit 26 will be described later.

(2-3-6) Control unit 25
The controller 25 receives output signals from various sensors provided in the indoor unit 20 . These various sensors may include a temperature sensor or a pressure sensor (not shown) in addition to the coolant leakage detection unit 26 . The controller 25 also drives the fan 23 and other actuators (not shown). The controller 25 further communicates with the controller 19 of the outdoor unit 10 via a communication line (not shown).

(3) Basic Operation of Refrigerating Cycle In the following, for the sake of simplicity, the basic operation of the refrigerating cycle of the air conditioner 90 will be described assuming that the refrigerant undergoes reactions involving phase changes such as condensation and evaporation. However, as long as the reaction generates heat and heat, it does not necessarily have to involve a phase change.

(3-1) Cooling Operation In FIG. 1, the four-way switching valve 13 of the outdoor unit 10 is connected as indicated by solid lines. Compressor 12 discharges high pressure gaseous refrigerant in the direction of arrow D. After that, the high-pressure gas refrigerant reaches the outdoor heat exchanger 14 through the four-way switching valve 13, where it is condensed into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant reaches the expansion valve 16, where it is depressurized to become a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant enters the indoor unit 20 through the opened liquid side shutoff valve 17 and the liquid connection pipe 31 in order. The low-pressure gas-liquid two-phase refrigerant reaches the indoor heat exchanger 22, where it absorbs heat in the process of evaporating into low-pressure gas refrigerant and provides cold energy to users. The low-pressure gas refrigerant passes through the gas communication pipe 32 and the open gas side shutoff valve 18 in order and enters the outdoor unit 10 . After passing through the four-way switching valve 13 , the low-pressure gas refrigerant is sucked into the compressor 12 .

(3-2) Heating Operation In FIG. 1, the four-way switching valve 13 of the outdoor unit 10 is connected as indicated by broken lines. Compressor 12 discharges high pressure gaseous refrigerant in the direction of arrow D. After that, the high-pressure gas refrigerant passes through the four-way switching valve 13 , then passes through the opened gas side shutoff valve 18 and the gas communication pipe 32 in order, and enters the indoor unit 20 . The high pressure gas refrigerant reaches the indoor heat exchanger 22 where it condenses into high pressure liquid refrigerant to provide heat to the user. The high pressure liquid refrigerant enters the outdoor unit 10 through the liquid connection pipe 31 and the opened liquid side shutoff valve 17 in order. The high-pressure liquid refrigerant reaches the expansion valve 16, where it is depressurized to become a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant reaches the outdoor heat exchanger 14, where it absorbs heat and evaporates into low-pressure gas refrigerant. Low-pressure gas refrigerant is sucked into the compressor 12 through the four-way switching valve 13 .

(4) Operation at Refrigerant Leakage (4-1) Configuration of Refrigerant Leak Detection Unit 26 FIG. In this example, the coolant leakage detector 26 has a coolant concentration sensor 26a, an amplifier 26b, an AD converter 26c, and a processor 26d. The refrigerant concentration sensor 26a outputs a concentration signal CS representing the concentration of the detected refrigerant. The amplifier 26b amplifies the density signal CS to a level suitable for AD conversion. The AD converter 26c AD-converts the amplified analog signal and outputs it as a digital signal. This digital signal represents the amount of refrigerant leakage determined based on the concentration signal CS. The processing unit 26 d compares the input signal I representing the refrigerant leakage amount with a predetermined threshold value, performs predetermined processing, outputs an output signal O, and sends the output signal O to the control unit 25 .

(4-2) Processing Characteristics of Refrigerant Leak Detection Section 26 FIGS. 4A to 4D show examples of processing in the processing section 26d.

In the example shown in FIG. 4A, the processing unit 26d compares the input signal I representing the amount of refrigerant leakage with a single threshold TH and outputs a binary output signal O. In the example shown in FIG.

In the example shown in FIG. 4B, the processing unit 26d compares the input signal I with a plurality of thresholds TH1 to TH3, and outputs the output signal O as a multistage signal. The output levels of each step divided by the thresholds TH1-TH3 may be arranged linearly or non-linearly as shown in FIG. 4B.

In the example shown in FIG. 4C, a smoother characteristic curve is created by employing a larger number of thresholds. This characteristic curve is non-linear because it has a small slope at the ends of the input range and a large slope in the middle region. Moreover, this characteristic curve has a so-called monotonically increasing relationship in which the output signal O increases as the input signal I representing the amount of refrigerant leakage increases. Of course, the characteristic curve may be linear instead of the illustrated curve, and this case also corresponds to a strictly monotonically increasing relationship.

The example shown in FIG. 4D also produces a smooth characteristic curve by employing multiple thresholds. This characteristic curve is also non-linear as a whole. Specifically, the characteristic curve has zero slope in the extreme regions of the input range and is linear with a slope in the middle region, and the junction between them is a curve. Also, the characteristic curve is a so-called monotonically increasing relationship in which the output signal O maintains its level or increases as the input signal I representing the amount of refrigerant leakage increases.

(4-3) Control of Fan 23 Based on Output Signal O The output signal O is sent from the coolant leakage detector 26 to the controller 25 . The controller 25 determines the rotation speed of the fan 23 based on the output signal O. FIG. Specifically, the controller 25 increases the rotation speed of the fan 23 as the output signal O increases. For example, the controller 25 determines the rotational speed of the fan 23 to be proportional to the output signal O. FIG. Alternatively, the controller 25 may increase the current value of the motor for the fan 23 as the output signal O increases. For example, the controller 25 may determine the current value of the motor for the fan 23 to be proportional to the output signal O.

(5) Features (5-1)
The rotation speed of the fan 23 increases when the refrigerant leakage amount is large, and the rotation speed of the fan 23 decreases when the refrigerant leakage amount is small. Therefore, when it is necessary to urgently deal with the leakage of the refrigerant, the leaked refrigerant is quickly diffused into the room and its concentration is lowered, and when it is not necessary to deal with the leakage of the refrigerant urgently, noise is suppressed.

(5-2)
Control can be performed such that the rotation speed of the fan increases as the refrigerant leakage amount increases. Therefore, an appropriate rotational speed is determined in consideration of the urgency of reducing the concentration of the refrigerant and suppressing the noise.

(5-3)
The rotation speed of the fan 23 is determined by the concentration signal CS output by the refrigerant concentration sensor 26a. Therefore, the required air volume is determined based on the concentration of the leaked refrigerant, and the rotation speed of the fan 23 is sufficient to generate the required air volume, so that the user feels uncomfortable due to unnecessary loud noise. can be suppressed.

(5-4)
It is possible to perform control such that the amount of refrigerant leakage is detected as multi-level values. Therefore, by determining the rotational speed in multiple stages according to the detection levels in multiple stages, the rotational speed suitable for the amount of refrigerant leakage can be realized.

(5-5)
The indoor unit 20 is of a ceiling-mounted type, such as a ceiling-embedded type or a ceiling-suspended type. Therefore, when the refrigerant leaks, the refrigerant falling from the ceiling can be diffused into the room and the concentration can be reduced.

(6) Modifications Modifications of this embodiment are shown below. In addition, you may combine several modifications suitably.

(6-1) Modification A: Wall Installation Type In the above-described embodiment, the indoor unit 20 is a ceiling installation type. Alternatively, the indoor unit may be wall-mounted. FIG. 5 shows a wall-mounted indoor unit 20A. The casing 21 is formed with a suction port 21a for sucking in room air and a blowout port 21b for blowing air into the room. The casing 21 is configured to be hung on a wall. Alternatively, casing 21 may be configured to be embedded in a wall.

According to this configuration, the indoor unit 20A is a wall-mounted type, for example, a wall-mounted type or a wall-embedded type. Therefore, when the refrigerant leaks, the refrigerant coming down from the wall can be diffused into the room and the concentration can be reduced.

(6-2) Modification B: Floor Installation Type In the above-described embodiment, the indoor unit 20 is a ceiling installation type. Alternatively, the indoor unit may be floor mounted. FIG. 5 shows a floor-mounted indoor unit 20B. The casing 21 is formed with a suction port 21a for sucking in room air and a blowout port 21b for blowing air into the room. The outlet 21b is provided at a location spaced apart from the floor surface. The casing 21 is configured to be placed on the floor. Alternatively, casing 21 may be configured to be fixed to the floor.

According to this configuration, the indoor unit 20B is of a floor installation type and has the outlet 21b spaced apart from the floor surface. Therefore, the refrigerant coming down from the blow-out port 21b can be diffused in the room and the concentration can be lowered.

(6-3) Modification C: Configuration of Refrigerant Leakage Detection Unit 26 In the above-described embodiment, the configuration of the refrigerant leakage detection unit 26 is as shown in FIG. 3, and a single refrigerant concentration sensor 27a is used. . Instead of this, the configuration of the coolant leakage detection unit 26 may be as shown in FIG. The refrigerant leakage detector 26 has a plurality of refrigerant concentration sensors 26a and a plurality of AD converters 26c. All the digital signals of the plurality of AD converters 26c are input to the processor 26d. The processing unit 26d compares the input signal I originating from each refrigerant concentration sensor 26a with different thresholds TH1 to TH3, respectively, and comprehensively considers the results to obtain the processing characteristics illustrated in FIGS. 4A to 4D. output signal O.

According to this configuration, even if any one of the refrigerant concentration sensors 26a fails, the degree of disruption of the processing characteristics is reduced. Therefore, it is easy to continue the control of the fan 23 stably.

20 indoor unit 21 casing 21a suction port 21b outlet 22 indoor heat exchanger 23 fan 25 control unit 26 refrigerant leakage detection unit

JP 2016-070594 A

Claims (3)

installed on the ceiling of the room, of an air conditioner (90) configured to form a refrigerant circuit (80) for circulating refrigerantceiling-mountedAn indoor unit (20),
a suction port (21a) for sucking air from the room;
an outlet (21b) for blowing conditioned air into the room;
a heat exchanger (22);
a fan (23);
a refrigerant leakage detection unit (26) that detects the amount of refrigerant leakage from the refrigerant circuit in multiple stages by having a plurality of threshold values;
a control unit (25) for controlling the rotation speed of the fan;
with
The control unit nonlinearly increases the rotational speed as the refrigerant leakage amount increases.
Indoor unit (20). The refrigerant leakage detection unit has a refrigerant concentration sensor (26a),
The refrigerant leakage amount is determined based on a concentration signal (CS) output from the refrigerant concentration sensor,
The indoor unit according to claim 1. The refrigerant leakage detection unit has a plurality of refrigerant concentration sensors,
The indoor unit according to claim 1 or 2 .

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