JP2016070594A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress damage in case a combustible refrigerant which has leaked from an indoor unit to the indoors catches fire.SOLUTION: An air conditioner uses a combustible refrigerant and it includes: a heat exchanger; an indoor fan; a gas sensor capable of detecting the combustible refrigerant which has leaked to the indoors; and a control unit for controlling the indoor fan. The control unit takes in a detection value of the gas sensor at non-drive time of the indoor fan, and when the detection value becomes equal to or greater than a first reference value, it determines that the combustible refrigerant has leaked, and when the detection value is higher than the first reference value and also equal to or less than a second reference value which is higher than the first reference value, it drives the indoor fan, and when the detection value exceeds the second reference value, it does not drive the indoor fan.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air conditioner including a floor-standing indoor unit using a combustible refrigerant such as R32.

  In an air conditioner using a flammable refrigerant such as R32 (including a slightly flammable refrigerant; the same applies hereinafter), the refrigerant should be introduced into the room from a heat exchanger in the indoor unit or a connection pipe between the indoor unit and the outdoor unit. Leakage may cause an accident such as a fire.

  In order to prevent such an accident due to refrigerant leakage, a conventional air conditioner has a gas sensor for detecting refrigerant leakage at the lower part of a casing such as an air outlet of an indoor unit. When the refrigerant is detected by the gas sensor, the indoor fan in the casing is driven.

  Since flammable refrigerants such as R32 are heavier than air, the refrigerant leaking into the room accumulates near the floor of the room. For this reason, the refrigerant accumulated near the floor in the room is diffused by the flow of air generated by driving the indoor fan. As a result, a technique is known in which the refrigerant concentration is set to be equal to or lower than the lower combustion limit concentration and an accident such as a fire is prevented (see, for example, Patent Document 1).

Japanese Patent No. 4599699

  Since the specific gravity of the combustible refrigerant such as R32 is larger than that of air, if the refrigerant leaks into the room while the operation of the air conditioner is stopped, the refrigerant stays near the floor of the room.

  The combustible refrigerant ignites when the concentration is within a predetermined range. The concentration range at this time is called a combustible concentration range. FIG. 6 shows an example of refrigerant concentration distribution in the indoor space 2 where refrigerant has leaked from the floor-standing indoor unit 20A based on LFL (lower limit of the flammable concentration range) and UFL (upper limit value of the flammable concentration range). FIG. In the refrigerant concentration distribution when the indoor fan is not driven, the refrigerant concentration gradually increases from the ceiling side to the floor side as shown in the figure.

  In this example, the indoor space 2 includes a region 3 near the floor surface 101 where the refrigerant concentration is higher than UFL, a region 5 near the ceiling surface 102 where the refrigerant concentration is lower than LFL, and a refrigerant concentration between LFL and UFL. It is divided into the area | region 4 (henceforth a "combustible density | concentration area | region") of the height between the said 2 area | regions which correspond to the said flammable concentration range.

  In this state, if the main power supply of the air conditioner is turned on and the indoor fan of the indoor unit 20A is driven, the refrigerant staying in the vicinity of the floor surface 101 in the room diffuses. As a result, there is a problem that the indoor combustible concentration region 4 is widened.

  In view of the circumstances as described above, an object of the present invention is to provide an air conditioner capable of preventing the expansion of the combustible concentration region 4 when a combustible refrigerant leaks into a room.

  In order to achieve the above object, an air conditioner according to an aspect of the present invention uses a combustible refrigerant, a heat exchanger, an indoor fan, and a gas sensor that detects the concentration of the combustible refrigerant leaked into the room. The air conditioner includes a floor-standing indoor unit including a control unit that controls the indoor fan, wherein the gas sensor is provided in a lower part of the indoor unit, and the control unit stops the indoor fan. Sometimes the detection value of the gas sensor is captured, and the indoor fan is driven when the detection value is not less than the first reference value and not more than the second reference value higher than the first reference value, When the detected value exceeds the second reference value, the indoor fan is not driven.

  The second reference value is obtained by calculating a weight of the combustible refrigerant in which the entire indoor space is in a combustible concentration range region of the combustible refrigerant based on a volume of the indoor space, and calculating a weight fraction of the combustible refrigerant. May be an estimated value of the concentration of the combustible refrigerant detected by the gas sensor in a state where the air leaks into the room.

  Alternatively, the second reference value may be a value that is an upper limit of the combustible concentration range of the combustible refrigerant.

  The combustible refrigerant may be R32 or a mixed refrigerant containing R32 or 70 wt% or more.

  ADVANTAGE OF THE INVENTION According to this invention, the danger which a combustible refrigerant | coolant can ignite can be reduced by limiting the area | region where the density | concentration of the combustible refrigerant | coolant leaked indoors from the indoor unit becomes the combustible density | concentration range.

It is a block diagram which shows the structure of the air conditioning apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the indoor unit control unit in the indoor unit of FIG. It is the front view which abbreviate | omitted the front panel and looked at the indoor unit of the air conditioning apparatus of this embodiment from the front. FIG. 4 is a right side cross-sectional view showing an internal configuration of the indoor unit in FIG. 3. It is a flowchart which shows the flow of control performed based on the detected value of a gas sensor in the indoor unit of the air conditioning apparatus of this embodiment. It is a figure which divides and shows the example of the refrigerant | coolant concentration distribution of the indoor space where the refrigerant | coolant leaked from the floor-standing type indoor unit on the basis of LFL and UFL.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an air conditioner according to an embodiment of the present invention.

  As shown in the figure, the air conditioner 1 of this embodiment includes an outdoor unit 10 and an indoor unit 20.

  The outdoor unit 10 includes a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, an outdoor expansion valve 14, an outdoor fan 15, and an outdoor unit control unit 16.

  The indoor unit 20 includes various sensors including an indoor heat exchanger 22, an indoor fan 23, an indoor unit control unit 25 that is a control unit that controls the indoor fan 23, and a gas sensor 24.

  The outdoor unit 10 and the indoor unit 20 are connected to each other so that the refrigerant can flow in and out through the liquid pipe 31 and the gas pipe 32.

  In the air conditioner 1, a flammable refrigerant (including a slightly flammable refrigerant; the same applies hereinafter) such as R32 is employed as the refrigerant.

  The compressor 11, the four-way valve 12, the outdoor heat exchanger 13, the outdoor expansion valve 14, the indoor heat exchanger 22, the liquid pipe 31, and the gas pipe 32 constitute a refrigerant circuit.

  The compressor 11 is a variable capacity compressor that can vary its operating capacity by being driven by a motor (not shown) whose rotational speed is controlled by an inverter.

  The four-way valve 12 has four ports a, b, c, and d. The port a is connected to the discharge side of the compressor 11 by a refrigerant pipe 17a. The port b is connected to one refrigerant inlet / outlet of the outdoor heat exchanger 13 through a refrigerant pipe 17b. The port c is connected to the suction side of the compressor 11 by a refrigerant pipe 17c. The port d is connected to the closing valve 18 that opens and closes the connection with the gas pipe 32 by a refrigerant pipe 17d.

  The outdoor heat exchanger 13 exchanges heat between the refrigerant and the outside air taken into the outdoor unit 10 by the outdoor fan 15. As described above, one refrigerant inlet / outlet of the outdoor heat exchanger 13 is connected to the port b of the four-way valve 12 via the refrigerant pipe 17b, and the other refrigerant inlet / outlet is connected to the closing valve 19 via the refrigerant pipe 17e. An outdoor expansion valve 14 is provided in the refrigerant pipe 17e.

  The outdoor fan 15 is driven by a motor (not shown) to take in the outside air into the outdoor unit 10, and to release the outside air heat exchanged with the refrigerant in the outdoor heat exchanger 13 to the outside of the outdoor unit 10. Generate a flow.

  The outdoor unit control unit 16 performs start-up, stop, and rotation speed control of the compressor 11, switching control of the four-way valve 12, opening degree control of the outdoor expansion valve 14, and drive control of the outdoor fan 15. The outdoor unit control unit 16 can receive various types of operation information from the indoor unit control unit 25 of the indoor unit 20, and can control the outdoor unit 10 based on the operation information. For example, the outdoor unit control unit 16 can at least control the start and stop of the compressor 11 in response to a request to start or stop the refrigerant circuit from the indoor unit control unit 25 of the indoor unit 20.

Next, the configuration of the indoor unit 20 will be described. The indoor unit 20 is a floor-standing indoor unit installed on the floor.
The indoor heat exchanger 22 exchanges heat between the refrigerant and indoor air taken into the indoor unit 20 by the indoor fan 23. One refrigerant inlet / outlet of the indoor heat exchanger 22 is connected to the closing valve 26 by a refrigerant pipe 28a. The other refrigerant inlet / outlet of the indoor heat exchanger 22 is connected to the closing valve 27 by a refrigerant pipe 28b. The closing valve 19 and the closing valve 27 are connected by a liquid pipe 31, and the closing valve 18 and the closing valve 26 are connected by a gas pipe 32, respectively.

  The indoor fan 23 is driven by a motor (not shown) to take outside air into the indoor unit 20, and air for releasing the outside air heat-exchanged with the refrigerant in the indoor heat exchanger 22 to the outside of the indoor unit 20. Generate a flow.

  The gas sensor 24 is a sensor that detects refrigerant leaked from the indoor unit 20 and is provided on the outer surface of the lower portion of the casing 203 of the indoor unit 20 described later. Thereby, the density | concentration of the leakage refrigerant | coolant collected near the floor surface of indoor space is detectable. The gas sensor 24 outputs a signal corresponding to the detected refrigerant concentration to the indoor unit control unit 25 as a detection result.

  The indoor unit control unit 25 is a control unit that transmits drive information to the outdoor unit control unit 16 of the outdoor unit 10 as well as driving control of the indoor fan 23.

FIG. 2 is a block diagram illustrating a configuration of the indoor unit control unit 25 that is a control unit.
The indoor unit control unit 25 is mounted on a control board stored in an electrical component box (not shown) of the indoor unit 20.

  The indoor unit control unit 25 includes a CPU 251, a storage unit 252, a communication unit 253, a sensor input unit 254, and an indoor fan drive unit 255.

  The storage unit 252 includes a ROM and a RAM. The storage unit 252 stores a control program for the indoor unit 20, detection values corresponding to detection signals from various sensors including the gas sensor 24, setting information regarding air conditioning operation by the user, and the like.

  The communication unit 253 is an interface that performs communication with the outdoor unit control unit 16 of the outdoor unit 10. This communication may be wired or wireless.

  The sensor input unit 254 takes in the output of various sensors including the gas sensor 24 of the indoor unit 20, converts it into digital data, and outputs it to the CPU 251 as a detection value corresponding to the detection signal of each sensor.

  The indoor fan drive unit 255 drives a motor (not shown) of the indoor fan 23 in accordance with a control command from the CPU 251.

  The CPU 251 receives communication data including detection values obtained by various sensors including the gas sensor 24 and control details of the outdoor unit 10 transmitted from the outdoor unit 10 through the sensor input unit 254 via the communication unit 253. The The CPU 251 receives a signal including operating conditions (set temperature, air volume, etc.) set by the user operating a remote controller (not shown). The CPU 251 performs drive control of the indoor fan 23, control of an alarm device, which will be described later, and the like based on the various pieces of input information. In addition, the CPU 251 transmits a signal including the operation instruction content based on the input various information to the outdoor unit 10 via the communication unit 253.

  The indoor unit control unit 25 is backed up by a storage battery (not shown), and even when the operation of the air conditioner 1 is stopped (when the power switch is off), the refrigerant concentration is detected by the gas sensor 24 and the alarm Control can be performed.

  In addition, the indoor unit 20 is provided with an alarm device (not shown). The alarm device gives an alarm when an abnormality such as refrigerant leakage occurs. In order to notify the occupant of the occurrence of an abnormality through vision and hearing, the alarm device includes a lamp made of an LED (light emitting diode) (visible to the resident through a front panel (not shown)) and a buzzer.

[Configuration of floor-standing indoor unit]
FIG. 3 is a front view of the indoor unit 20 of the air-conditioning apparatus 1 according to the present embodiment as viewed from the front without the front panel.
FIG. 4 is a right side cross-sectional view showing the internal configuration of the indoor unit 20 of FIG.

  This indoor unit 20 is a floor-standing indoor unit. This indoor unit 20 has a housing 201. The casing 201 includes a base 202 and a casing 203. The casing 203 is a rectangular parallelepiped member that covers the indoor heat exchanger 22 and the indoor fan 23 described above from the five surfaces of the front surface, the back surface, the left side surface, the right side surface, and the ceiling surface. In the housing 201, an electrical box 256 that houses the indoor heat exchanger 22, the indoor fan 23, the substrate of the indoor unit control unit 25, and the like are housed.

  A suction port 205 that takes air into the interior of the indoor unit 20 from the outside is provided at a portion of the front panel 204 of the casing 203 that faces the indoor heat exchanger 22. Further, a discharge port 206 for discharging air from the interior of the indoor unit 20 is provided at the lower portion of the front panel 204.

  An indoor fan 23 is disposed on the back side of the indoor heat exchanger 22. By driving the indoor fan 23, air is sucked into the interior of the indoor unit 20 from the outside through the suction port 205 of the front panel 204. The air sucked into the indoor unit 20 exchanges heat with the refrigerant when passing through the indoor heat exchanger 22, and then forms a gap between the indoor fan 23 and the inner surface of the back plate 207 of the casing 203. It flows downward and passes through the discharge port 206 of the front panel 204 and is discharged outside.

  Further, in the indoor unit 20, a gas sensor 24 for detecting the refrigerant concentration leaked into the room is disposed on the side surface of the casing 201 (casing 203), for example.

[Control of the indoor unit 20 based on the detection value of the gas sensor 24]
Next, the control executed based on the detection value of the gas sensor 24 in the indoor unit 20 of the air conditioner 1 of the present embodiment will be described.
FIG. 5 is a flowchart showing the control flow.

  This control is started when the main power supply of the air conditioner 1 is turned on.

  When the main power is turned on to the indoor unit 20, the indoor unit control unit 25 of the indoor unit 20 is turned on. Subsequently, the gas sensor 24 of the indoor unit 20, the outdoor unit control unit 16 of the outdoor unit 10 and the like are turned on. become. At this time, the indoor fan 23 of the indoor unit 20 remains stopped.

  In the indoor unit 20, the refrigerant concentration is detected by the gas sensor 24, and the detection value of the gas sensor 24 is input to the indoor unit control unit 25 (step S101).

  In the indoor unit control unit 25, the detection value of the gas sensor 24 is converted into digital data by the sensor input unit 254 and input to the CPU 251. The CPU 251 compares the detected value with the first reference value according to the control program stored in the storage unit 252 (step S102). Here, the first reference value is a value determined for the purpose of determining that a refrigerant leak has occurred and that there is a region in the indoor space where the refrigerant concentration in the air is in the combustible concentration range.

  When the detected value is lower than the first reference value (NO in step S102), the CPU 251 continues the refrigerant concentration detection by the gas sensor 24 without doing anything. When the detected value is greater than or equal to the first reference value (YES in step S102), the CPU 251 controls the alarm device to generate an alarm indicating an abnormality (step S103). Subsequently, when the cooling or heating operation is started at the same time as the main power is turned on, the CPU 251 performs control to turn off the cooling or heating operation of the air conditioner 1 (step S104).

  Next, the CPU 251 compares the detected value with the second reference value (step S105). Here, the second reference value will be described.

  As the second reference value, for example, the weight of the flammable refrigerant in which the entire indoor space is in the flammable concentration range region of the flammable refrigerant is calculated based on the volume of the indoor space, A value obtained by preliminarily calculating the concentration detected by the gas sensor 24 in a state of leaking into the space can be employed. In this case, the estimated value of the refrigerant concentration corresponding to the weight of the combustible refrigerant is stored in the storage unit 252. When the air conditioner 1 is installed, the volume of the indoor space is input to the air conditioner 1, and the estimated value of the refrigerant concentration corresponding to the weight of the combustible refrigerant calculated based on the input volume of the indoor space is the second. Is set as the reference value.

For example, since the LFL of R32 is 0.307 kg / m ³ , the value obtained by multiplying the LFL by the volume of the room is the total refrigerant weight. In the test or the like, the refrigerant concentration at the gas sensor attachment height when R32 of this weight leaks from the indoor unit 20 is detected in advance and stored in the storage unit 252.

Further, even if the refrigerant concentration does not reach the flammable concentration range throughout the room, the diffusion of the refrigerant by the indoor fan 23 prevents the flammable concentration region from expanding beyond the time when the indoor fan 23 is driven. Therefore, it is preferable to set a value lower than the above estimated value as the second reference value. The second reference value may be a value that is the upper limit (UFL) of the flammable concentration range of the refrigerant. For example, when R32 is used as the refrigerant, the combustible concentration range of R32 is 0.307 kg / m ^{3 to} 0.712 kg / m ³ (14.4 vol% to 33.4 vol%). Thus, 0.712 kg / m ³ (33.4 vol%) is the second reference value. In addition, since the flammable concentration range of a flammable refrigerant | coolant changes with kinds of refrigerant | coolant, it shall be suitably set according to the refrigerant | coolant to be used.

  When the detected value is equal to or smaller than the second reference value (YES in step S105), the CPU 251 gives a control command to the indoor fan drive unit 255 to drive the indoor fan 23 (step S106). That is, the indoor fan 23 is driven to diffuse the refrigerant, thereby extinguishing the combustible concentration region in the room.

  If the detected value exceeds the second reference value (NO in step S105), if the indoor fan 23 is driven to diffuse the refrigerant, the indoor combustible concentration region is expanded. Leave as it is. That is, as shown in FIG. 6, when the indoor fan 23 is driven, the refrigerant leaks into the indoor space 2 so that the entire indoor space 2 becomes the combustible concentration region 4, or near the floor surface of the indoor space 2. When the refrigerant concentration exceeds the combustible concentration range upper limit (UFL) (region 3), the indoor fan 23 is not driven.

  Thereafter, for example, when ventilation is performed such as opening a window by a resident or serviceman who has confirmed the alarm, the detected value falls below the second reference value, the indoor fan 23 is turned on, and the detected value is the first reference value. If it falls below the value, the indoor fan 23 is turned off.

  As described above, the air-conditioning apparatus 1 according to the present embodiment determines whether or not the combustible concentration region is widened by driving the indoor fan 23, separately from the first reference value for detecting refrigerant leakage. The second reference value is provided. The indoor unit control unit 25 of the indoor unit 20 compares the detection value of the gas sensor 24 with the second reference value, and does not drive the indoor fan 23 when the detection value exceeds the second reference value. Thereby, the danger that the combustible refrigerant is ignited can be reduced by minimizing the region where the indoor combustible concentration region is within the combustible concentration range.

<Modification>
In the above embodiment, the control based on the detection value of the gas sensor 24 is started by turning on the main power supply of the air conditioner 1. However, the above control is performed when the operation of the air conditioner 1 is stopped. It may be started automatically at a fixed time period.

  In this modification, when the above control is repeated with a short time period of about several seconds, the detected value of the gas sensor 24 is less than or equal to the second reference value before the detected value of the gas sensor 24 exceeds the second reference value. Since the indoor fan 23 is driven at this time, a state in which the detection value of the gas sensor 24 exceeds the second reference value is less likely to occur than in the above embodiment. However, for example, when a disaster such as an earthquake causes a crack in the refrigerant piping in the indoor unit 20 and a large amount of refrigerant leaks in a short time, and the above control is temporarily disabled due to a power failure, When the power is restored, the above control functions as a means for minimizing the risk that the combustible refrigerant may be ignited by minimizing the region where the concentration of the leaked refrigerant falls within the combustible concentration range.

  The combustible refrigerant may be a mixed refrigerant containing 70% by weight or more of R32 in addition to R32, or a mixed refrigerant containing propane or propane.

DESCRIPTION OF SYMBOLS 1 ... Air conditioning apparatus 20 ... Indoor unit 22 ... Indoor heat exchanger 23 ... Indoor fan 24 ... Gas sensor 25 ... Indoor unit control unit

Claims (4)

Using a flammable refrigerant,
A heat exchanger,
With indoor fans,
A gas sensor for detecting the concentration of the combustible refrigerant leaked into the room;
An air conditioner including a floor-standing indoor unit having a control unit for controlling the indoor fan,
The gas sensor is provided in the lower part of the indoor unit,
The controller is
The detected value of the gas sensor is taken in when the indoor fan is stopped, and the indoor fan is detected when the detected value is not less than a first reference value and not more than a second reference value higher than the first reference value. And the indoor fan is not driven when the detected value exceeds the second reference value. The air conditioner according to claim 1,
The second reference value is obtained by calculating a weight of the combustible refrigerant in which the entire indoor space is in a combustible concentration range region of the combustible refrigerant based on a volume of the indoor space, and calculating a weight fraction of the combustible refrigerant. Is an estimated value of the concentration of the combustible refrigerant detected by the gas sensor in a state where the air leaks into the room. The air conditioner according to claim 1,
The second reference value is a value that is an upper limit of a combustible concentration range of the combustible refrigerant. The air conditioner according to any one of claims 1 to 3,
The flammable refrigerant is an air conditioner that is R32 or a mixed refrigerant containing R32 or more by 70 weight percent.

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