JP6540106B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner provided with a floor-standing indoor unit using a flammable 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 in the room from the heat exchanger in the indoor unit or the connection piping between the indoor unit and the outdoor unit. Leaks may lead to fires and other accidents.

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

  Since the flammable refrigerant such as R32 is heavier than air, the refrigerant that has leaked into the room accumulates near the floor of the room. For this reason, the refrigerant accumulated near the floor surface of the room is diffused by the flow of air generated by driving the indoor fan. By this, the refrigerant concentration is made less than the combustion lower limit concentration, and the technique which prevents accidents, such as a fire, is known (for example, refer to patent documents 1.).

Patent No. 4599699 gazette

  Since the flammable refrigerant such as R32 has a specific gravity larger than that of air, if the refrigerant leaks into the room during the shutdown of the air conditioner, the refrigerant stays near the floor of the room.

  The flammable refrigerant ignites when the concentration is within a predetermined range. The concentration range at this time is called the flammable concentration range. FIG. 7 divides an example of the refrigerant concentration distribution in the indoor space 2 where the refrigerant leaks from the floor-standing indoor unit 20A, based on LFL (lower limit of the flammable concentration range) and UFL (upper limit of the flammable concentration range) FIG. In the case of the refrigerant concentration distribution when the indoor fan is not driven, the concentration of the refrigerant gradually increases from the ceiling to the floor as shown in the figure.

  In this example, the indoor space 2 has 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 Divided into areas 4 (hereinafter referred to as "combustible concentration areas") of height between the above two areas corresponding to the flammable concentration range of

  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 accumulated in the vicinity of the floor surface 101 of the room is diffused. As a result, there is a problem that the combustible concentration region 4 in the room is expanded.

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

In order to achieve the above object, an air conditioner according to an aspect of the present invention uses a flammable refrigerant, a heat exchanger, an indoor fan, and a gas sensor that detects the concentration of the flammable refrigerant that has leaked into the room. An air conditioner comprising a floor-mounted indoor unit having a control unit for controlling the indoor fan, wherein the gas sensor is provided at a lower gas sensor provided at a lower portion of the indoor unit and at an upper portion of the indoor unit. The upper gas sensor, wherein the control unit takes in the detection values of the lower gas sensor and the upper gas sensor, and the detection value of the lower gas sensor indicates that the refrigerant concentration in the air is the flammable concentration range in the space of the room and the first reference value or more consisting region has a value can be determined to be occurring, and the second below the reference value lower than the detection value of said first reference value of the upper gas sensor In some cases, after the refrigerant agitation step of driving the indoor fan and the refrigerant agitation step, the detection values of the lower gas sensor and the upper gas sensor are taken in, and the detection value of the upper gas sensor and the lower gas sensor If the detected value is lower than the first reference value and equal to or higher than a third reference value higher than the second reference value, a refrigerant agitation inhibition step is performed to stop the indoor fan.

  Alternatively, the first reference value may be a value which is the lower limit of the flammable concentration range of the flammable refrigerant.

  The flammable refrigerant may be a mixed refrigerant containing 70% by weight or more of R32 or R32.

  According to the present invention, by minimizing the region in which the concentration of the flammable refrigerant leaked from the indoor unit into the room becomes the flammable concentration range, the risk of causing the flammable refrigerant to ignite can be reduced.

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. It is right side surface sectional drawing which shows the internal structure of the indoor unit of FIG. It is a flowchart which shows the flow of the 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 flowchart which shows the flow of the 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 refrigerant concentration distribution of indoor space which the refrigerant leaked from a 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 the configuration of an air conditioner according to an embodiment of the present invention.

  As shown to the same figure, the air conditioning apparatus 1 of this embodiment has the outdoor unit 10 and the indoor unit 20. As shown in FIG.

  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, and an indoor unit control unit 25 that is a control unit that controls the indoor fan 23, a lower gas sensor 24, and an upper gas sensor 29.

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

  And in this air conditioning apparatus 1, for example, a flammable refrigerant such as R32 (including a slightly flammable refrigerant, hereinafter the same) is adopted 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 change 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, 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 by a refrigerant pipe 17 b. The port c is connected to the suction side of the compressor 11 by the refrigerant pipe 17c. The port d is connected by a refrigerant pipe 17 d to a closing valve 18 which opens and closes a connection with the gas pipe 32.

  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. One refrigerant inlet / outlet of the outdoor heat exchanger 13 is connected to the port b of the four-way valve 12 by the refrigerant pipe 17b as described above, and the other refrigerant inlet / outlet is connected to the closing valve 19 by the refrigerant pipe 17e. The outdoor expansion valve 14 is provided on 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 exchange the heat with the refrigerant in the outdoor heat exchanger 13 for discharging the outside air to the outside of the outdoor unit 10. Generate a flow.

  The outdoor unit control unit 16 controls startup, stop and rotation of the compressor 11, switching control of the four-way valve 12, opening control of the outdoor expansion valve 14, and drive control of the outdoor fan 15. Further, the outdoor unit control unit 16 can receive various 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 control at least the start and stop of the compressor 11 in response to the start request and the stop request of 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-mounted indoor unit installed on the floor.
The indoor heat exchanger 22 exchanges heat between the refrigerant and the indoor air taken into the interior of 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 28 a. The other refrigerant inlet / outlet of the indoor heat exchanger 22 is connected to the closing valve 27 by a refrigerant pipe 28 b. The shutoff valve 19 and the shutoff valve 27 are connected by a liquid pipe 31, and the shutoff valve 18 and the shutoff 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 interior of the indoor unit 20 and exchange the heat with refrigerant in the indoor heat exchanger 22 for discharging the outside air to the outside of the indoor unit 20. Generate a flow.

  The lower gas sensor 24 is a sensor for detecting the refrigerant leaking from the indoor unit 20, and is provided on the outer surface of the lower portion of a casing 203 of the indoor unit 20 described later. Thereby, the concentration of the leaked refrigerant accumulated near the floor of the indoor space can be detected. The lower gas sensor 24 outputs a signal corresponding to the detected refrigerant concentration to the indoor unit control unit 25 as a detection result.

  The upper gas sensor 29 is a sensor for detecting the refrigerant leaking from the indoor unit 20, and is provided on the outer surface of the casing 203 of the indoor unit 20 described later or the upper portion of the front panel 204. Thus, the concentration of the leaked refrigerant at a position higher than the floor surface of the indoor space can be detected. 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 controls driving of the indoor fan 23 and further transmits various operation information and the like to the outdoor unit control unit 16 of the outdoor unit 10.

FIG. 2 is a block diagram showing a configuration of the indoor unit control unit 25 which 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 is configured of a ROM and a RAM. The storage unit 252 stores detection values corresponding to detection signals from various sensors including the control program of the indoor unit 20 and the lower gas sensor 24 and the upper gas sensor 29, setting information on air conditioning operation by the user, and the like.

  The communication unit 253 is an interface that communicates 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 outputs of various sensors including the lower gas sensor 24 and the upper gas sensor 29 of the indoor unit 20, converts them into digital data, and transmits the converted values to the CPU 251 as detection values corresponding to detection signals of each sensor. Output.

  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 is communication data including detection values obtained by various sensors including the lower gas sensor 24 and the upper gas sensor 29 via the sensor input unit 254 and control contents of the outdoor unit 10 transmitted from the outdoor unit 10. It is input through the communication unit 253. A signal including an operating condition (set temperature, air volume, etc.) set by operating a remote controller (not shown) by the user is input to the CPU 251. The CPU 251 performs drive control of the indoor fan 23 and control of an alarm, which will be described later, based on the input various information. Further, the CPU 251 transmits a signal including the content of the operation instruction 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 by the lower gas sensor 24 and the upper gas sensor 29 Detection and control of the alarm.

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

[Configuration of floor-standing indoor units]
FIG. 3 is a front view of the indoor unit 20 of the air conditioning apparatus 1 of the present embodiment as viewed from the front with the front panel omitted.
FIG. 4 is a right side sectional view showing an internal configuration of the indoor unit 20 of FIG.

  The indoor unit 20 is a floor type indoor unit. The indoor unit 20 has a housing 201. The housing 201 is composed of a base 202 and a casing 203. The casing 203 is a rectangular parallelepiped shaped member that covers the indoor heat exchanger 22 and the indoor fan 23 described above from the five surfaces of the front, back, left, right, and ceiling. In the housing 201, an indoor heat exchanger 22, an indoor fan 23, an electrical box 256 storing a substrate of the indoor unit control unit 25, and the like are accommodated.

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

  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 interior of the indoor unit 20 exchanges heat with the refrigerant when passing through the indoor heat exchanger 22, and then the gap between the indoor fan 23 and the inner side surface of the back plate 207 of the casing 203 It flows downward, and is discharged to the outside through the discharge port 206 of the front panel 204.

  Further, in the indoor unit 20, a lower gas sensor 24 and an upper gas sensor 29 for detecting the concentration of refrigerant leaking into the room are disposed, for example, on the side surface of the housing 201 (casing 203). The upper gas sensor 29 is preferably disposed near the upper portion of the suction port 205 of the front panel 204.

[Control of the indoor unit 20 based on detected values of the lower gas sensor 24 and the upper gas sensor 29]
Next, in the indoor unit 20 of the air conditioner 1 of the present embodiment, control performed based on the detection values of the lower gas sensor 24 and the upper gas sensor 29 will be described.
5 and 6 are flowcharts showing the flow of the control.

  This control is started by turning on the main power supply of the air conditioner 1.

  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, and then, the lower gas sensor 24, the upper gas sensor 29, and the outdoor unit control of the outdoor unit 10 are controlled. Each unit 16 is turned on. 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 lower gas sensor 24 and the upper gas sensor 29, and the detection values of the respective gas sensors are input to the indoor unit control unit 25 (step S101).

  In the indoor unit control unit 25, detection values of the lower gas sensor 24 and the upper gas sensor 29 are converted into digital data by the sensor input unit 254 and input to the CPU 251. The CPU 251 determines whether the leaked refrigerant has been detected according to the control program stored in the storage unit 252 (step S102). Here, the detection of the leaked refrigerant means that the refrigerant is detected even with a slight concentration.

  When the CPU 251 does not detect the leaked refrigerant (NO in step S102), the CPU 251 returns to step S101 and detects the refrigerant concentration by the lower gas sensor 24 and the upper gas sensor 29. When the CPU 251 detects the leaked refrigerant (YES in step S102), it controls the alarm to generate an alarm indicating an abnormality (step S103). Subsequently, when the cooling or heating operation is started simultaneously with the turning on of the main power, the CPU 251 performs control to turn off the cooling operation or the heating operation of the air conditioner 1 (step S104).

  Next, the CPU 251 compares the detection value of the lower gas sensor 24 (hereinafter referred to as the lower detection value) with the first reference value according to the control program stored in the storage unit 252 to detect the upper gas sensor 29. The value (hereinafter referred to as the upper detection value) is compared with the second reference value (step S105). Here, the first reference value will be described first.

The first reference value is stored in the storage unit 252, and it is determined whether a refrigerant leakage occurs and a region of the refrigerant concentration in the air is in the flammable concentration range in the indoor space at the detection position of the lower gas sensor 24 The value may be a value determined for the purpose of determining the lower limit (LFL) of the flammable concentration range of the refrigerant. For example, when R32 is used as the refrigerant, since the flammable concentration range of R32 is 0.307 kg / m ^{3 to} 0.712 kg / m ³ (14.4 vol% to 33.4 vol%), the lower limit of the flammable concentration range and The first reference value is 0.307 kg / m ³ (14.4 vol%). In addition, since the flammable concentration range of the flammable refrigerant differs depending on the type of refrigerant, it is appropriately set according to the refrigerant to be used.

  Next, the second reference value will be described. The second reference value is stored in storage unit 252, and is set to a value lower than the first reference value. Since the flammable refrigerant such as R32 has a specific gravity larger than that of air, if the refrigerant leaks into the room during the shutdown of the air conditioner, the refrigerant stays near the floor of the room. Therefore, the refrigerant concentration near the floor is detected by the lower gas sensor 24, and when the lower detection value is equal to or higher than the first reference value, the indoor fan 23 is driven to diffuse the refrigerant accumulated in the vicinity of the floor. However, if the upper gas sensor 29 has a high refrigerant concentration at a position higher than the floor surface of the indoor space, the weight of the flammable refrigerant is the area of the flammable refrigerant in the entire indoor space. Is leaking from the indoor unit, and the diffusion of the refrigerant by the indoor fan 23 is considered to expand the flammable concentration region more than the time when the indoor fan 23 is driven. Therefore, the second reference value is set to a value lower than the first reference value (for example, 25% of the first reference value), and unless the detection value of the upper gas sensor 29 becomes less than the second reference value. The indoor fan 23 is not driven.

  When the lower detection value is equal to or more than the first reference value and the upper detection value is equal to or less than the second reference value (YES in step S105), the CPU 251 drives the indoor fan 23 A control command is given to 255 (step S106). That is, by driving the indoor fan 23 to diffuse the refrigerant, the combustible concentration region in the room is eliminated. Steps S105 and S106 are collectively referred to as a refrigerant stirring step.

  When the lower detection value is less than the first reference value and the upper detection value exceeds the second reference value (NO in step S105), the indoor fan 23 is driven to diffuse the refrigerant. The indoor fan 23 is kept off because there is a possibility that the flammable concentration area may expand. That is, as shown in FIG. 7, the refrigerant leaks into the indoor space 2 so that the entire indoor space 2 becomes the flammable concentration region 4 when the indoor fan 23 is driven, or the floor surface of the indoor space 2 is near If the concentration of the refrigerant exceeds the upper limit of the flammable concentration range (UFL) (region 3), the indoor fan 23 is not driven.

  After step S106, in the indoor unit 20, the refrigerant concentration is detected by the lower gas sensor 24 and the upper gas sensor 29, and the detection values of the respective gas sensors are input to the indoor unit control unit 25 (step S201 in FIG. 6). ).

  In the indoor unit control unit 25, detection values of the lower gas sensor 24 and the upper gas sensor 29 are converted into digital data by the sensor input unit 254 and input to the CPU 251. The CPU 251 compares the lower and upper detection values with the third reference value in accordance with the control program stored in the storage unit 252 (step S202). Here, the third reference value will be described.

  As the third reference value, a value lower than the first reference value and higher than the second reference value is set. This is because the refrigerant continuously leaks from the indoor unit 20 even if the flammable concentration region in the room is eliminated by diffusing the refrigerant accumulated in the vicinity of the floor surface by the above-described driving of the indoor fan 23 (step S106). If so, the refrigerant concentration in the entire indoor space approaches the flammable concentration range. Therefore, the third reference value is lower than the first reference value and higher than the second reference value (for example, 75% of the first reference value) is set, and the lower and upper detection values are the third. When it becomes more than the reference value of, the driving of the indoor fan 23 is stopped.

  If the lower and upper detection values are less than the third reference value (NO in step S202), the CPU 251 detects the refrigerant concentration by the lower gas sensor 24 and the upper gas sensor 29 while maintaining the drive of the indoor fan 23. to continue. If the lower and upper detection values are the third reference value (YES in step S202), the CPU 251 gives a control command to the indoor fan drive unit 255 to stop the indoor fan 23 (step S203), and then the indoor unit At 20, the refrigerant concentration is detected by the lower gas sensor 24 and the upper gas sensor 29, and the detected value of each gas sensor is input to the indoor unit control unit 25 (step S204), and the process proceeds to step S105 in FIG. . Steps S202 and S203 are referred to as a refrigerant agitation prohibition step.

  After that, for example, when the refrigerant diffused due to the passage of time starts to stay near the floor again, the determination criterion of step S105 (the lower detection value is equal to or higher than the first reference value and the upper detection value is the second reference value) If the following conditions are satisfied and the indoor fan 23 is turned on (step S106) but ventilation is performed by opening the window by the resident or serviceman who confirmed the alarm, the lower detection value is set to the first reference value. The lower indoor fan 23 is turned off.

  As described above, the air conditioner 1 of the present embodiment is provided with a reference value for determining whether or not the flammable concentration region is expanded by driving the indoor fan 23 using two gas sensors. The indoor unit control unit 25 of the indoor unit 20 has a refrigerant stirring step of driving the indoor fan 23 when the lower detection value is the first reference value or more and the upper detection value is the second reference value or less; After the stirring step, when the lower and upper detection values are equal to or more than the third reference value, the refrigerant stirring prohibition step is performed to stop the indoor fan 23. As a result, by minimizing the range in which the concentration in the indoor flammable concentration range is the flammable concentration range, the risk of igniting the flammable refrigerant can be reduced.

  The flammable refrigerant may be, in addition to R32, a mixed refrigerant containing 70 weight percent or more of R32, or propane or a mixed refrigerant containing 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 (3)

Using flammable refrigerant, heat exchanger, indoor fan,
A gas sensor that detects the concentration of the flammable refrigerant that has leaked into the room;
An air conditioner comprising a floor-mounted indoor unit having a control unit that controls the indoor fan.
The gas sensor may be a lower gas sensor provided at a lower portion of the indoor unit and an upper gas sensor provided at an upper portion of the indoor unit,
The control unit
The detection values of the lower gas sensor and the upper gas sensor are taken in, and the detection value of the lower gas sensor is a value that can be determined that there is a region where the refrigerant concentration in air is in the flammable concentration range in the space of the room. in certain first reference value or more and the refrigerant stirring step of driving the indoor fan when the detected value of the upper gas sensor is equal to or less than the second reference value lower than the first reference value,
After the refrigerant stirring step, the detection values of the lower gas sensor and the upper gas sensor are taken in, and the detection value of the upper gas sensor and the detection value of the lower gas sensor are lower than the first reference value. A refrigerant agitation prohibiting step of stopping the indoor fan if the third reference value is higher than the reference value of
Run the air conditioner.
An air conditioner according to claim 1, wherein
An air conditioner, wherein the first reference value is a value that is the lower limit of the flammable concentration range of the flammable refrigerant. The air conditioner according to any one of claims 1 to 2, wherein
The air conditioning apparatus, wherein the flammable refrigerant is a mixed refrigerant containing 70% by weight or more of R32 or R32.

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