Room air conditioner

Abstract

To avoid a fire disaster and an explosion caused by gas leakage occurring when a room air conditioner using a flammable gas refrigerant is operated or stopped.SOLUTION: A room air conditioner includes, at the upper side of the inside of a housing 20 of an outdoor master unit 2, a system control board part 50 in which a first circuit 3 for controlling an operation of an indoor slave unit 1 and a second circuit 4 for controlling start / stop of operation of the outdoor master unit 2 and air conditioning operation in response to an operation command signal are sealed by an explosion-proof insulation film 34. Further, a gas sensor 40 configured to detect leakage of a refrigerant is installed at the lower side of the inside of the housing 20. Furthermore, the system control board part 50 includes an invalidation signal generation circuit and a fan rotation continuation circuit which invalidate operation control of the room air conditioner when a detection signal of the gas sensor 40 occurs.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to air conditioning technology, and particularly to a room air conditioner using a combustible gas as a refrigerant.

Background Art

[0002] The room air conditioner in the present invention means the entire heat pump type air conditioning technology including residential and commercial use, and is generally a device called an "air conditioner". Historically, so-called "Freon gases" (CFC, HCFC) have been used as refrigerants for heat pump type room air conditioners. However, due to the perspective of global environmental destruction, particularly the problem of global warming, usage regulations have been imposed, and currently, the use of new Freon-based gas refrigerants is prohibited.

[0003] As an alternative, a conversion to HFC (hydrofluorocarbon), which is called "alternative Freon", has been recommended. However, since HFC has a global warming potential (GWP: Global Warning Potential) that reaches thousands of times that of carbon dioxide (CO 2 ), a refrigerant to replace "alternative Freon" is required. Note that GWP is a quantification of the global warming ability when CO 2 is set to 1. However, at the 28th Meeting of the Parties to the Montreal Protocol, the amended protocol (Kigali Amendment, effective January 1, 2019) that stipulates the phased reduction obligations of HFC production and consumption, etc., although HFC is not an ozone-depleting substance, it has been regulated due to its high greenhouse effect.

[0004] Refrigerants to replace "alternative Freon" include carbon dioxide (CO 2 ) and hydrocarbon gases (such as propane and butane). However, carbon dioxide has not been widely adopted because its operating pressure is high, requiring advanced countermeasures in the design of equipment. On the other hand, hydrocarbons such as propane and butane are non-toxic as long as they do not burn, and are extremely useful as refrigerants to replace "alternative Freon" by taking measures against flammability.

[0005] Furthermore, at the International Electrotechnical Commission (IEC) spring meeting in 2019, the filling quantity limit standards for weakly flammable refrigerants (A2), slightly flammable refrigerants (A2L), and flammable refrigerants (A3) were revised. For example, the filling quantity limit of propane (A3) was increased from 150 g to 500 g, which expanded the applications of hydrocarbon natural refrigerants.

[0006] Known hydrocarbon refrigerants include propane (R290) and butane (isobutane: R600a). These refrigerants do not damage the ozone layer, have a low global warming potential (GWP), high heat transfer efficiency, and low environmental impact. Therefore, propane in particular is recommended for introduction in Europe and other regions.

[0007] As described above, typical hydrocarbon gases that are heavier than air as refrigerants are propane and butane, and these hydrocarbon gases are flammable. While they have the advantage of low environmental impact as described above, it is an important issue to be solved to thoroughly implement safety measures to prevent air pollution, fires, or explosions associated with gas leakage, which is a concern when using flammable gases as refrigerants.

[0008] Generally, a room air conditioner (hereinafter also referred to as an air conditioner) installed in a building such as a residence is composed of an indoor unit equipped with a heat absorber / radiator, etc., and an outdoor main unit equipped with a refrigerant compressor, etc. The heat absorber / radiator of the indoor unit and the refrigerant compressor of the outdoor main unit are connected by a refrigerant pipe (usually a copper pipe), and refrigerant (gas) is circulated according to the refrigeration cycle to deheat (absorb heat) or heat (radiate heat) the discharged air of the indoor unit to perform air conditioning in the room, as described above. There are also some that house the indoor unit and the outdoor main unit in a common housing.

[0009] Figure 4 is a schematic diagram for briefly explaining the mechanism of a room air conditioner, and it illustrates the refrigerant circulation system. In Figure 4, reference numeral 100 denotes the heat absorber side housing, 200 denotes the radiator side housing, 500 denotes the refrigerant pipe (heat medium circulation pipe), 130 denotes the expansion valve, and 140 denotes the compressor / condenser. Auxiliary equipment such as a control circuit for controlling the operation is not shown in the figure.

[0010] In Figure 4, in the heat absorber side housing 100, heat absorption of the interior of the housing 100 is performed by the evaporation gas in the refrigerant pipe of the refrigerant by the heat absorption radiator 150. Heat absorption is indicated by "→C". The heat-absorbed refrigerant is liquefied (including semi-liquefaction) by the compression condenser 140.

[0011] The liquefied refrigerant is stored in the radiator side housing 200 and releases heat to the outside of the radiator side housing 200 by the heat dissipation radiator 250. The released heat is indicated by "→H". The heat-dissipated refrigerant is vaporized by the expansion valve 130 and circulates to the heat absorption radiator 150 stored in the heat absorber side housing 100. As a result, the interior of the heat absorber side housing 100 is processed into a cooled atmosphere.

[0012] In the mode in which the room air conditioner is used as a cooling machine, the heat absorber side housing 100 becomes the indoor unit side, and in the mode in which it is used as a heating machine, the radiator side housing 200 becomes the indoor unit side.

[0013] This type of air conditioning equipment inevitably has joints as described above that require processing during installation. It is impossible to completely deny the occurrence of refrigerant leakage from the vicinity of this joint. Even if piping connections are made in accordance with the regulations during the installation of the air conditioner, it cannot be denied that refrigerant leakage may occur due to subsequent environmental changes, aging deterioration of materials, or external impacts such as earthquakes. Note that not only at the joint part, but also various connection parts inside the equipment may have the same possibility of leakage. Also, in the case where a large external force is applied to the refrigerant pipe, it is possible that the pipe may be damaged in the middle and gas leakage may occur.

[0014] As described above, conventional room air conditioners generally use a non-flammable gas containing chlorofluorocarbons as the refrigerant from the viewpoint of the heat exchange efficiency of the refrigerant and the safety aspect of preventing the occurrence of fires and the like due to refrigerant leakage caused by the above-mentioned reasons. However, due to concerns about ozone layer depletion, the use of refrigerants containing chlorine and chlorofluorocarbons has been prohibited, and HFCs that do not contain chlorine are used as substitutes. However, since HFCs have an extremely high global warming potential (GWP), the adoption of new refrigerants has been explored.

[0015] As new refrigerants, the use of hydrocarbon gases such as propane and butane, which are natural refrigerants, or carbon dioxide (CO 2 ) has come to be considered. However, as described above, although carbon dioxide is non-flammable and non-toxic, it is difficult to design equipment due to its high compression pressure for liquefaction, and it is not practical from the cost aspect for use in ordinary residences.

[0016] On the other hand, when a flammable gas such as propane or butane is used as the refrigerant, it is necessary to prevent the risk of fire and explosion caused by refrigerant leakage as described above. The indoor unit and the outdoor main unit constituting the air conditioner house a wiring board (generally a printed circuit board, simply referred to as a board) equipped with an electric circuit for supplying electric energy for their operation and an electronic circuit for controlling the operation of the air conditioner.

[0017] During the operation of these wiring boards, a spark or the like may rarely occur between the wiring circuits and component terminals. At this time, if a flammable refrigerant gas leaks near the circuit board and drifts, ignition may occur in the leaked gas, causing a fire or an explosion. Such accidents need to be prevented.

[0018] As examples of the prior art related to explosion-proof measures when a flammable gas is used as the refrigerant, Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4 can be cited. Patent Document 1 discloses an air conditioner that includes a first electrical component having a control circuit for comprehensively controlling an indoor unit of an air conditioner using a flammable refrigerant, and installs one or both of the first and second electrical components for controlling the indoor unit outdoors at a position higher than the refrigerant connection portion to improve safety.

[0019] Patent Document 2 discloses a substrate unit having a resin film that covers at least one of a plurality of metal components mounted on a wiring substrate and an electronic component as a safety holding component, and the resin film has a thermal conductivity of at least 1.0 W / mk and a dielectric breakdown strength of at least 3.0 kV / mm.

[0020] Patent Document 3 discloses an air conditioner in which electrical components of an indoor slave unit and an outdoor master unit are arranged at the upper part of a casing so as to be located above a heat exchanger. Further, Patent Document 4 discloses a heat pump that, when a malfunction such as a failure or malfunction of an outdoor fan occurs and the ventilation performance cannot be maintained, and a malfunction of leakage of a flammable refrigerant occurs, and when an outdoor fan drive command for instructing the drive of the outdoor fan is received, stops the operation of the heat pump when the rotational speed of the outdoor fan is equal to or lower than a predetermined target rotational speed.

Prior Art Documents

Patent Documents

[0021]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0022] All of the prior arts disclosed in the above-mentioned documents assume the use of hydrocarbon gases (such as propane and butane) as flammable gases in the refrigerant. The specific gravities of these hydrocarbon gases are 1.56 (propane) and 2.09 (butane) respectively when the specific gravity of air is set to 1.0, and the average molar molecular weights are approximately 29 g / mol for air, approximately 44 g / mol for propane, and approximately 58 g / mol for butane, on the premise that they are heavier than air.

[0023] In Patent Documents 1 and 3 above, considering refrigerant leakage, the electrical components (usually composed of a substrate) are installed above the device so as to avoid contact with the leaked gas as much as possible even if a spark occurs in the electrical components. In addition, in Patent Document 2, in the mounting area of elements where spark safety is particularly required, a resin film is used to cover the substrate on which the electrical components are mounted to prevent the possibility that the explosion-proof standard of the substrate cannot be ensured due to the temperature rise of the substrate. The substrate unit has a resin film with a thermal conductivity of at least 1.0 W / mk and a dielectric breakdown strength of at least 3.0 kV / mm.

[0024] In the prior arts disclosed in Patent Documents 1 and 3 above, the possibility that the air flow around the indoor sub-unit or the outdoor main unit reaches the electrical components due to the entrainment of the leaked gas is not considered. In addition, the resin film described above is filled only in a specific area corresponding to the mounting area of elements where spark safety is particularly required (a Zener diode in the embodiment) in the substrate unit of Patent Document 2. Regarding the wiring and elements in other areas mounted on the substrate, the reduction of the dielectric breakdown ability due to the installation environment and the adhesion of dust over time is not considered.

[0025] And Patent Documents 1 to 4 above do not consider measures against refrigerant leakage when the air conditioner is stopped. That is, even if there is refrigerant leakage during the operation of the air conditioner, it diffuses into the atmosphere due to the rotation of the fan and it is difficult for the gas to accumulate to a dangerous concentration around the outdoor main unit and its vicinity. However, when the air conditioner is not in use (in the stopped state) and refrigerant leaks, it accumulates inside and around the outdoor main unit, and there is a risk of ignition due to the generation of sparks or the like that may occur when the operation start switch is turned on.

[0026] Even if a gas leakage sensor is installed in the indoor slave unit and the outdoor master unit, the gas leakage on the indoor slave unit side can be detected, but there are cases where the sound and light signals indicating the abnormal situation emitted by the gas leakage sensor on the outdoor master unit side cannot be recognized indoors. For countermeasures against gas leakage during the operation of the air conditioner (operation mode), countermeasures such as those in Patent Document 4 described above are possible, but it is difficult to take countermeasures against gas leakage in the stopped state of the air conditioner (operation stop mode).

[0027] An object of the present invention is to avoid fires and explosions caused by gas leakage in a room air conditioner that uses a flammable gas as a refrigerant. In particular, it is to provide a room air conditioner that can avoid the risk of fires and explosions ignited by insulation breakdown (sparks), corona discharge (hereinafter simply referred to as corona), arc discharge (hereinafter simply referred to as arc), etc. occurring in the mounted control board (circuit board), etc., including the operation stop mode of the air conditioner.

Means for Solving the Problems

[0028] A typical configuration of the present invention for achieving the above object is described below. Here, for ease of understanding of the present invention, reference numerals used in the drawings of the embodiments described later are attached to the configuration of the invention.

[0029] (1) The room air conditioner according to the present invention includes an indoor slave unit 1 provided with an indoor radiator and an indoor fan for generating cooling or heating air installed in a space such as a living room, and a refrigerant pipe 5 for circulating a flammable refrigerant between the space, and is composed of a compressor 14 for compressing / condensing the refrigerant and an outdoor master unit 2 provided with an outdoor master unit fan 8.

[0030] And, above the inside of the housing 20 of the outdoor master unit 2, there is provided a system control board unit 50 in which a first circuit 3 for controlling the operation of the indoor slave unit 1 and a second circuit 4 for starting / stopping the operation of the outdoor master unit 2 and controlling the air conditioning operation in response to an operation command signal are sealed with an explosion-proof insulating film 34, and a gas sensor 40 for detecting refrigerant leakage is installed below the inside of the housing 20. Also, the system control board unit 50 is provided with an invalidation signal generation circuit and a fan rotation continuation circuit that invalidate the operation control of the room air conditioner when a detection signal of the gas sensor 40 is generated.

[0031] (2) A display means 19 for displaying the detection state to the surroundings when the gas sensor 40 detects gas leakage is provided outside the housing 20 of the outdoor master unit 2.

[0032] (3) The invalidation signal generation circuit 51 includes a fan rotation continuation circuit 52 that prohibits a change in the operation state when a detection signal of the sensor 40 is generated during the operation of the room air conditioner and continues only the rotation of the fan 8 of the outdoor master unit 2 to stop other control operations.

[0033] (4) The operation invalidation signal generation circuit 51 includes a full system operation prohibition signal generation circuit 53 that disables the operation of the indoor slave unit and the outdoor master unit when the command signal is for starting operation in a state where a detection signal of the gas sensor 40 is generated when the room air conditioner is stopped.

[0034] (5) The room air conditioner according to claim 1, characterized in that the flammable refrigerant is a hydrocarbon gas, and any one of butane, cyclopentane, isobutane, propane, or a mixed gas of two or more thereof is suitable.

Effect of the Invention

[0035] According to the present invention, by using an insulating film with good spark resistance (including corona resistance and arc resistance) as an explosion-proof film for coating a substrate on which electric circuits and elements are mounted when using a flammable gas as a refrigerant, it is possible to avoid the risk of fire and explosion caused by insulation breakdown occurring inside and around the substrate, and to provide a refrigeration / air conditioning machine that minimizes the influence from the environment such as temperature and humidity.

[0036] During operation, by prohibiting changes in the control content of the air conditioning operation and continuing the operation of the fan, the leaked gas is diffused so that it does not stay in the housing of the outdoor master unit and the mixing ratio with air does not reach the explosion / combustion value. This can avoid ignition accidents caused by gas leakage.

[0037] Furthermore, when there is a gas leak, starting the operation of the equipment is avoided, preventing accidents caused by spark generation due to circuit operation and other unpredictable ignition causes.

Brief Description of the Drawings

[0038]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0039] Hereinafter, embodiments of the room air conditioner according to the present invention will be described in detail with reference to the drawings of the examples.

Examples

[0040] FIG. 1 is a schematic diagram for explaining Example 1 when the present invention is applied to a separate type air conditioner. Since the basic installation mode is the same as that of the conventional example, there are also parts that are repeatedly described. In FIG. 1, reference numeral 1 is an indoor slave unit, and 2 is an outdoor unit. The indoor slave unit 1 is installed near the ceiling inside the outer wall 9 of the building. The outdoor master unit 2 is installed outside the outer wall 9 on the floor side (ground side).

[0041] The refrigerant pipe 5 connecting the indoor slave unit 1 and the outdoor master unit 2 is piped through the outer wall 9. This refrigerant pipe 5 is joined to the connecting pipe (not shown) at the refrigerant inlet and outlet of the indoor unit 1 and the outdoor unit 2. The same joining structure is used when adding to the refrigerant pipe 5.

[0042] Further, the first board 3 equipped with an electric circuit for controlling the operation of the indoor sub-unit 1 is installed in the upper part of the housing of the outdoor unit 2 as a system control board unit 50 together with the second board 4 equipped with an electric circuit for controlling the operation of the outdoor unit 2. The entire periphery of the first board 3 and the second board 4 is covered with an explosion-proof insulating film 34.

[0043] FIG. 2 is an explanatory diagram of a configuration example of the outdoor main unit shown in FIG. 1, where (a) is a front view and (b) is a side perspective view. The outdoor main unit 2 is installed on the installation table 10. Inside the housing 20, a compressor 14 and a fan 8 are installed, and a system control board unit 50 is built in the upper part of the housing 20. The system control board unit 50 is fireproof shielded by a shield 54.

[0044] The fan 8 is driven by a motor 81, and the compressor 14 is integrated with a motor and housed in a sealed container. Also, a gas sensor 40 is installed in the lower part of the housing 20. An LED 19 for notifying the surroundings that the gas sensor has detected gas leakage is provided at an appropriate location outside the housing 20.

[0045] FIG. 3 is an overall explanatory diagram of a control circuit example of the separate type room air conditioner according to the present invention. This room air conditioner rectifies the commercial power supply AC by a rectifier circuit 15 and supplies it to the motor part M of the compressor 14 via an inverter 16 and a motor control circuit 17 to drive the compressor part C. Also, the motor control circuit 17 supplies power to the motor 81 of the fan 8.

[0046] The indoor unit 1 of the room air conditioner has a remote controller 60 and a remote control receiver 30. When an operation command is transmitted from the remote controller 60, the system control board unit 50 is given an operation command. During normal operation, a normal operation similar to the conventional one is started.

[0047] The system control board unit 50 is provided with an invalidation signal generation circuit 51. The invalidation signal generation circuit 51 is provided with a fan rotation continuation circuit 52 and a full system operation prohibition signal generation circuit 53. When the detection signal of the gas sensor 40 is generated during the operation (operation mode) of the room air conditioner, the invalidation signal generation circuit 51 prohibits the change of the operation state, and includes a fan rotation continuation circuit 52 that continues only the rotation of the fan 8 of the outdoor master unit 2 and stops other control operations. By invalidating the operations of the compressor etc. without stopping the fan, the leaked gas is diffused into the atmosphere, thereby suppressing the combustion and explosion of the gas.

[0048] Further, when the detection signal of the gas sensor 40 is generated in the state where the room air conditioner is in the operation stop state (stop mode) and the command signal is a command for starting operation, the operation invalidation signal generation circuit 51 includes a full system operation prohibition signal generation circuit 53 that disables the operation of the indoor slave unit and the outdoor master unit. This suppresses the ignition of the leaked gas due to the unexpected spark etc. of the electric circuit or electronic circuit. Note that the fan rotation continuation signal and the full system operation prohibition signal that continue only the rotation of the fan 8 of the outdoor master unit 2 and stop other control operations can be formed by a logic circuit.

[0049] With the configuration of the first embodiment, since the operations of the electric circuit, the substrate mounted with elements, and the accessory circuit when using a flammable gas as the refrigerant are prohibited, a refrigeration / air conditioning machine that avoids the risk of fire and explosion due to gas leakage can be provided.

Industrial Applicability

[0050] The present invention can be similarly applied not only to the above-described separate type air conditioner but also to an indoor function / indoor function integrated type air conditioner. Needless to say, the present invention can be applied not only to R290 but also to the operation and control of equipment that handles flammable gases of other natural refrigerants.

Explanation of Reference Numerals

[0051] 1 ··· Indoor sub-unit 2 ··· Outdoor main unit 3 ··· First substrate 4 ··· Second substrate 5 ··· Refrigerant pipe 6 ··· Control wire 8 ··· Fan 81 ··· Fan motor 9 ··· Outer wall 10 ··· Installation base 11(11a, 11b) ··· Refrigerant pipe connection part 12 ··· Commercial power supply 13 ··· Expansion valve 14 ··· Compressor 15 ··· Rectifier circuit 16 ··· Inverter 17 ··· Motor drive control circuit 19 ··· LED (lamp) 20 ··· Housing of outdoor main unit 30 ··· Remote signal receiving circuit 40 ··· Gas sensor 50 ··· System control board unit 51 ··· Invalidation signal generation circuit 52 ··· Fan rotation continuation circuit 53 ··· All-system operation prohibition signal generation circuit 54 ··· Shield

Claims

1. A room air conditioner comprising an indoor slave unit having an indoor radiator and an indoor slave unit fan, and an outdoor master unit having a compressor for compressing / condensing the refrigerant and an outdoor master unit fan, the indoor slave unit being connected to the indoor space by a refrigerant pipe for circulating a flammable refrigerant, a system control board section, the entirety of which is sealed with an explosion-proof insulating film, including a first circuit for controlling the operation of the indoor slave units and a second circuit for starting / stopping the operation of the outdoor master unit and controlling air conditioning in response to an operation command signal, disposed inside the upper part of the housing of the outdoor master unit; a drive control circuit for the compressor and the motor of the outdoor master unit, and a total system operation prohibition circuit; and a gas sensor for detecting leakage of refrigerant disposed inside the lower part of the housing of the outdoor master unit. The room air conditioner is further characterized in that the system control board portion has a disable signal generating circuit and a fan rotation continuing circuit that disable the operation control of the room air conditioner when a detection signal is generated from the gas sensor.

2. 2. The room air conditioner according to claim 1, further comprising a display means provided on the outside of the housing of the outdoor main unit for displaying to the surroundings a detection state when the gas sensor detects a gas leak.

3. The room air conditioner according to claim 1, characterized in that the disable signal generating circuit includes a fan rotation continuation circuit which prohibits a change in the operating state when a detection signal from the gas sensor is generated during operation of the room air conditioner, and which continues only the rotation of the fan of the outdoor parent unit and stops other control operations.

4. The room air conditioner according to claim 1, characterized in that the disable signal generating circuit includes a total system operation prohibition signal generating circuit which disables operation of the indoor slave unit and the outdoor master unit when the gas sensor detection signal is generated when the room air conditioner is stopped and the command signal is to start operation.

5. 2. The room air conditioner according to claim 1, wherein the flammable refrigerant is a hydrocarbon gas selected from the group consisting of butane, cyclopentane, isobutane, and propane, or a mixture of two or more of these gases.

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