Patent Description:
As is well known, when an air conditioner is used for a long period of time, dust adheres to the inside of an indoor unit, particularly to an indoor heat exchanger. Dust gives adequate nutrients for the proliferation of bacteria. After a cooling operation or a dehumidifying operation, a humidity inside the indoor unit increases to provide an environment excellent in the propagation of bacteria.

The proliferation and propagation of bacteria and the growth of mold inside the indoor unit cause air blown out of the indoor unit toward a room to seriously affect a user's health. The mold, when growing intensely inside the indoor unit, clogs an air hole (a blow-out path) in the indoor unit, which may decrease an amount of air to be blown out of the indoor unit and may constitute a hinderance to the performance and use of the air conditioner.

Consequently, the air conditioner industry is faced with technical issues of how to inhibit the proliferation and propagation of bacteria and how to reduce the growth of mold.

<CIT> discloses a known method of cleaning an air conditioner, the method including: (S1) a condensation step of causing an air conditioner to carry out a cooling operation to form condensate on a surface of an indoor heat exchanger, thereby cleaning the surface of the indoor heat exchanger; (S2) a frost formation step of causing the air conditioner to carry out the cooling operation to form a frost layer on the surface of the indoor heat exchanger; (S3) a heating step of causing the air conditioner to carry out a heating operation to perform defrosting, thereby cleaning and sterilizing the surface of the indoor heat exchanger; and (S4) a ventilation step of operating an indoor unit in a ventilation mode to promptly dry the indoor heat exchanger and to decrease a temperature in the heat exchanger (see claim <NUM> and FIG. <NUM> of <CIT>).

The foregoing method of cleaning the air conditioner disclosed in <CIT> adjusts the operating state of the air conditioner, thereby executing the four steps of: condensation (i.e., removing floating dust on the surface of the indoor heat exchanger, with the condensate); frost formation (i.e., separating dust, impurities, and the like from the surface of the indoor heat exchanger); heating (i.e., defrosting, secondary cleaning; removing from the indoor heat exchanger the dust, impurities, and the like thus separated and sterilizing the indoor heat exchanger at high temperature); and ventilation (i.e., drying the indoor heat exchanger while decreasing the temperature of the indoor heat exchanger) in this order. This method thus cleans and sterilizes the inside of the air conditioner.

<CIT> discloses a known air adjuster including: an indoor unit that includes an indoor heat exchanger and an indoor fan; and a control unit that controls the indoor fan, wherein the control unit carries out an indoor heat-exchange heat applying operation and, during the indoor heat-exchange heat applying operation, causes the indoor heat exchanger to function as a condenser and controls the indoor fan, thereby maintaining an indoor heat-exchange temperature which is a temperature of the indoor heat exchanger, at a predetermined first temperature or more and reducing the number of mold and bacteria in the indoor heat exchanger (see claim <NUM> of <CIT>). In addition, the control unit carries out the indoor heat-exchange heat applying operation immediately after a state in which the indoor heat exchanger functions as an evaporator (e.g., immediately after a cooling operation) (see claim <NUM> of <CIT>). The inside of the air adjuster is thus dried to reduce the number of mold and bacteria and to inhibit the propagation of mold and bacteria.

As is well known, the growth and propagation of mold can be classified into four stages of a spore stage, a cystoid spore germination stage, a mycelial growth stage, and a mold proliferation stage.

At the spore stage, spores, because of their thick and dense walls, have characteristics such as considerably high resistance to high temperature, to low temperature, and to radiation. Therefore, spores can survive even under a considerably disadvantageous environment. It is no exaggeration to say that spores have the highest vitality in the world. Spores are dispersed throughout a room through the flow of air, the movement of a person or animal, and the like and are gradually deposited on a surface of a wall body or building material. Spores in a wall body are mainly derived from a building material itself, air, or the like.

At an initial stage, these spores are in a dormant state. When the cystoid spores absorb adequate nutrients and a temperature and humidity in an environment reach appropriate conditions, the cystoid spores begin germinating (the cystoid spore germination stage), the mycelia grow (the mycelial growth stage), and the mold promptly begin propagating (the mold propagation stage). Vast propagation of mold results in formation of mold colonies.

With regard to mold growth conditions, some studies have revealed that the growth of mold pertains to elements such as a temperature, a humidity (a relative humidity), a nutrient, and a duration of exposure and, in particular, mainly pertains to a temperature and a humidity.

As for the majority of mold propagation, the optimum temperature range is <NUM> to <NUM>, the lowest temperature is <NUM> or less, and the highest temperature is <NUM> or more.

Within the temperature range suitable for the growth of mold, most kinds of mold undergo enhanced activation of intracellular proteins and enzymes with an increase in temperature, resulting in acceleration of biochemical reaction and improvement in a growth rate. In a case where the temperature exceeds a limit temperature of mold growth, the continuous increase in temperature may cause irreversible damage to temperature-sensitive components (e.g., proteins, nucleic acids, etc.) in the cell. When the temperature exceeds its optimum value, the growth rate decreases promptly with the increase in temperature.

Microorganisms may be classified depending on growth suitability relative to humidity into:.

The majority of bacteria, yeast fungi, and some kinds of mold, such as Penicillium and Trichoderma, correspond to the hygrophytic microorganisms. Most of mold correspond to medium-humidity microorganisms. Some kinds of koji mold, such as Aspergillus glaucus, Aspergillus candidus, and Aspergillus terreus, correspond to the xerophytic microorganisms.

Typically, a mold cystoid spore is relatively resistant to drought and is therefore capable of surviving only for a certain period of time even under a dry environment. If the environment changes, the mold cystoid spore keeps growing after absorbing adequate moisture.

Examples of indoor mold may include mainly Aspergillus, Penicillium, and Trichoderma. As for Aspergillus, the mycelial growth rate becomes maximum at a humidity from <NUM>% to <NUM>%. As for Penicillium and Trichoderma, the growth rate becomes maximum at a humidity of approximately <NUM>%. Typically, mold cystoid spores germinate only at a relative humidity more than <NUM>%.

<CIT> which is a prior application by the applicant discloses an influence of a relative humidity value on a process of inhibiting mold and bacteria and also discloses an inside cleaning operation control unit configured to switch from a stop state to a dry shock sate, thereby rapidly decreasing a humidity inside an indoor unit and efficiently inhibiting the propagation of mold and bacteria (see paragraphs [<NUM>], [<NUM>] and [<NUM>] of <CIT>).

According to <CIT> and <CIT>, although an indoor heat exchanger can be cleaned and dried, internal environments (particularly a temperature and a humidity) of an indoor unit cannot be adjusted; therefore, mold prevention and sterilization inside the indoor unit are insufficient. In other words, the propagation and survival environment of bacteria and mold are not destroyed, and the indoor heat exchanger can be cleaned only once.

Particularly in <CIT>, a heating operation is carried out immediately after a cooling operation, which causes a large temperature difference in air to be blown out through a blow-out port. This configuration therefore makes a person in a room feel uncomfortable and fails to achieve energy saving.

Another example of the prior art can be seen in dd <CIT>. Accordingly, how to realize an air conditioning system control method capable of achieving mold prevention and sterilization by destroying the propagation and survival environment of bacteria and mold is a technical issue to be solved urgently.

In order to solve the foregoing technical issue, an object of the present invention, which is defined in claim <NUM>, is to provide an air conditioning system control method for controlling an air conditioning system that decreases a relative humidity inside an indoor unit within a predetermined time to destroy the propagation and survival environment of bacteria and mold, thereby achieving mold prevention and sterilization inside the indoor unit.

Another object of the present invention is to provide an air conditioning system control method for controlling an air conditioning system capable of efficiently achieving mold prevention and sterilization inside an indoor unit in an energy-saved manner.

In order to achieve one or more inventive objects described above, a first aspect of the present invention provides an air conditioning system control method for controlling an air conditioning system including an outdoor unit, an indoor unit, and a control unit, the outdoor unit including a compressor and an outdoor heat exchanger, the indoor unit including an indoor heat exchanger, the compressor, the outdoor heat exchanger, and the indoor heat exchanger being connected with pipes to constitute a refrigerant circuit in which a refrigerant circulates, the control unit being configured to control constituent members of the refrigerant circuit in the air conditioning system and to execute a mold prevention operation mode, in which the mold prevention operation mode includes an inside humidity decrease stage, at the inside humidity decrease stage, when a preset condition is satisfied, the control unit controls the air conditioning system and starts up a humidity decrease process of decreasing a relative humidity, the humidity decrease process includes an air blowing operation of blowing air out of the indoor unit toward a room, and by the inside humidity decrease stage, a relative humidity inside the indoor unit is decreased within a predetermined time such that a ratio between the relative humidity and a relative humidity before the inside humidity decrease stage falls within a preset range that enables destruction of propagation and a survival environment of bacteria and mold.

According to the foregoing configuration, the mold prevention operation mode includes the inside humidity decrease stage. By the inside humidity decrease stage, furthermore, the relative humidity inside the indoor unit is decreased within the predetermined time such that the ratio between the relative humidity and the relative humidity before the inside humidity decrease stage falls within the preset range that enables destruction of the propagation and survival environment of bacteria and mold. This configuration therefore achieves real mold prevention inside the indoor unit, which is different from a simple one-time cleaning after propagation of bacteria and mold.

In addition, since the indoor unit is quickly dried before a mold cystoid spore germination period, the growth of mold is reset again. This configuration therefore inhibits germination of mold and considerably reduces the number of bacteria as compared with the number of bacteria in a case where an indoor unit is dried naturally.

According to the foregoing configuration, the control unit controls the air conditioning system. When the relative humidity before the inside humidity decrease stage is a preset value (e.g., a relative humidity of <NUM>%) or more, the control unit executes the humidity decrease process of decreasing the relative humidity inside the indoor unit, from the relative humidity before the inside humidity decrease stage. In the rainy season, the continuous rainy weather, or the season with high humidity such as the rainy weather, or after the end of a long-hours cooling or dehumidifying operation in summer, the humidity (the relative humidity) inside the indoor unit already satisfies a high-humidity condition. In such a case, the control unit may control the air conditioning system to merely execute the humidity decrease process, and does not need to execute the humidity increase process prior to the humidity decrease process. This configuration therefore efficiently achieves mold prevention and sterilization inside the indoor unit in an energy-saved manner.

According to the first aspect of the present invention, the preset condition includes one of or at least two of a condition that the relative humidity inside the indoor unit reaches a predetermined value, a condition that a humidity of indoor air reaches a predetermined value, a condition that an integrated operating time of a cooling operation or a dehumidifying operation reaches a predetermined value, and a condition that an integrated time of continuous increase in environmental temperature reaches a predetermined value.

A second aspect of the present invention provides the air conditioning system control method according to the first aspect of the present invention, in which the inside humidity decrease stage of the mold prevention operation mode further includes a humidity increase process of increasing a humidity inside the indoor unit, and when the relative humidity before the inside humidity decrease stage is lower than the preset value, at the inside humidity decrease stage, the humidity increase process is executed, and then the humidity decrease process is executed.

According to the foregoing configuration, when the relative humidity before the inside humidity decrease stage does not reach (i.e., is less than) the preset value (e.g., the relative humidity of <NUM>%), the inside of the air conditioner at this time is at a normal humidity and, in turn, is in a relatively dry state. In this case, although the inside humidity decrease process is executed, executing the humidity increase process and then executing the humidity decrease process may cause the ratio between the relative humidity inside the indoor unit subjected to the humidity decrease by the inside humidity decrease stage and the relative humidity before the inside humidity decrease stage to more advantageously fall within the preset range that enables destruction of the propagation and survival environment of bacteria and mold.

A third aspect of the present invention provides the air conditioning system control method according to the second aspect of the present invention, in which the humidity increase process includes a cooling operation, and during the cooling operation, the control unit controls the constituent members of the refrigerant circuit, including the compressor, to cause the indoor heat exchanger to function as an evaporator.

According the foregoing configuration, the cooling operation during which the indoor heat exchanger functions as an evaporator is carried out during the execution of the humidity increase process at the inside humidity decrease stage. Therefore, controlling the refrigerant that circulates in the refrigerant circuit by the compressor achieves humidity increase on the secondary side (the blow-out side) of the indoor heat exchanger, produces an advantageous effect of the humidity increase, and improves control accuracy. With this configuration, the inside humidity decrease stage causes the ratio between the relative humidity inside the indoor unit subjected to the humidity decrease by the inside humidity decrease stage and the relative humidity before the inside humidity decrease stage to more advantageously fall within the preset range that enables destruction of the propagation and survival environment of bacteria and mold.

A fourth aspect of the present invention provides the air conditioning system control method according to the third aspect of the present invention, in which the humidity increase process further includes a step of stopping the compressor after a lapse of the predetermined time.

According to the foregoing configuration, the compressor is stopped in the execution of the humidity increase process at the inside humidity decrease stage. Therefore, the moisture mainly on the secondary side of the indoor heat exchanger is dispersed to the primary side of the indoor heat exchanger to achieve humidity increase on the primary side (the suction side) of the indoor heat exchanger, that is, humidity increase inside the entire indoor unit. This configuration thus ensures the advantageous effects of the mold prevention and sterilization.

A fifth aspect of the present invention provides the air conditioning system control method according to the fourth aspect of the present invention, in which when the compressor stops, the control unit intermittently operates the indoor fan of the indoor unit.

A sixth aspect of the present invention provides the air conditioning system control method according to the fourth aspect of the present invention, in which the humidity increase process further includes a step of determining whether frost formation occurs in the indoor heat exchanger in a case of the cooling operation, when frost formation occurs in the indoor heat exchanger, the indoor fan of the indoor unit is continuously operated, and/or when no frost formation occurs in the indoor heat exchanger, the indoor fan of the indoor unit is stopped.

According to the foregoing configuration, the indoor fan is intermittently operated during the execution of the humidity increase process at the inside humidity decrease stage. Alternatively, in the case of the cooling operation, the control unit determines whether frost formation occurs in the indoor heat exchanger. When frost formation occurs in the indoor heat exchanger, the indoor fan is continuously operated. This configuration therefore achieves prompt defrosting and promptly increases an inside humidity. When no frost formation occurs in the indoor heat exchanger, the indoor fan is stopped. This configuration therefore adequately mixes airflows inside the indoor unit and increases the humidity inside the entire air conditioner. Adjusting the operating state of the indoor fan in accordance with the specific state of the indoor heat exchanger improves control accuracy, achieves energy saving, advantageously stabilizes the air conditioning system, and ensures user's comfortability.

A seventh aspect of the present invention provides the air conditioning system control method according to the sixth aspect of the present invention, in which the humidity decrease process further includes a heat applying operation, and during the heat applying operation, the control unit controls the constituent members of the refrigerant circuit, including the compressor, to apply heat by causing the indoor heat exchanger to function as a condenser or the control unit controls a heat applying member to apply heat.

During the execution of the humidity decrease process at the inside humidity decrease stage, the control unit carries out the air blowing operation to decrease the relative humidity inside the indoor unit, without carrying out the heat applying operation. Carrying out the air blowing operation promptly and effectively decreases the humidity inside the indoor unit, which makes a user comfortable without increasing a temperature of air to be blown out of the indoor unit.

According to the foregoing configuration, both the air blowing operation and the heat applying operation are carried out. Carrying out the heat applying operation achieves further dry and mold prevention and produces more preferable advantageous effects of sterilization.

An eighth aspect of the present invention provides the air conditioning system control method according to the seventh aspect of the present invention, in which during the heat applying operation, the control unit intermittently operates the indoor fan of the indoor unit.

According to the foregoing configuration, when the heat applying operation is carried out in the execution of the humidity decrease process at the inside humidity decrease stage in the mold prevention operation mode, the air inside the indoor unit is undesirably heated. In the case of the heat applying operation, the control unit intermittently operates the indoor fan. This configuration thus increases a temperature difference in air to be blown out of the indoor unit and prevents user's health from being affected.

A ninth aspect of the present invention provides the air conditioning system control method according to the first aspect of the present invention, in which the relative humidity inside the indoor unit is decreased to be not more than <NUM> times the relative humidity before the inside humidity decrease stage, within the predetermined time.

The foregoing configuration ensures an advantageous effect of mold prevention inside the indoor unit and improves control accuracy, without imposing an excessive load on the air conditioner.

A tenth aspect of the present invention provides the air conditioning system control method according to the first aspect of the present invention, in which the air conditioning system further includes a humidity sensor, and the humidity sensor is disposed near the indoor heat exchanger, near a suction port in the indoor unit, near a blow-out port in the indoor unit (<NUM>), or in a space to be adjusted. According to the foregoing configuration, the relative humidity inside the indoor unit is directly acquired or calculated from the detection data by the humidity sensor. Therefore, the control unit causes, for example, the humidity sensor to detect a temperature inside the indoor unit (a relative humidity at startup, a humidity adjustment value subjected to humidity increase by a present predetermined cycle in the humidity increase process, or a relative humidity in the humidity decrease process) in real time. This configuration enables an immediate response to a change in temperature inside the indoor unit, the change being fed back from the humidity sensor. This configuration thus improves control accuracy.

An eleventh aspect of the present invention provides the air conditioning system control method according to any one of the first to tenth aspects of the present invention, in which the air conditioning system includes a plurality of the indoor units, and at least one of or all the indoor units executes or execute the mold prevention operation mode.

According to the foregoing configuration, all the indoor units execute the mold prevention operation mode at the same time. This configuration thus avoids an excessively complicated determination process and switching process by an actuator and collectively completes the mold prevention and sterilization for the entire air conditioning system. Moreover, some of the indoor units execute the mold prevention operation mode. In particular, the indoor units execute the mold prevention operation mode as necessary or individually depending on the use frequency of the different indoor units. This configuration thus avoids unnecessary redundant mold prevention and sterilization for an indoor unit where no mold propagates. The air conditioning system thus becomes more intelligent and achieves energy saving. On the other hand, this configuration achieves early mold prevention and sterilization for an indoor unit where mold has already propagated. This configuration therefore avoids an adverse influence on a user's health owing to air blown out of some indoor units where mold has already propagated.

A twelfth aspect of the present invention provides the air conditioning system control method according to the eleventh aspect of the present invention, in which when at least one of the indoor units which is an operative device executes the mold prevention operation mode, the remaining indoor units which are non-operative devices stop operating.

According to the foregoing configuration, the non-operative devices stop operating when the operative device executes the mold prevention operation mode. This configuration therefore achieves further energy saving in the entire air conditioning system and ensures an advantageous effect of mold prevention. In this case, as to actuator control, in the humidity decrease process, an electric valve, such as an expansion valve, in the indoor unit (non-operative device) that does not execute the mold prevention operation mode is closed. This configuration thus prevents an increase in temperature of a room where the non-operative device is present or prevents the temperature from increasing more than necessary. Alternatively, the electric valve is slightly opened to prevent the compressor in the air conditioning system from becoming short of the refrigerant. This configuration thus ensures safety and stability in performance of the air conditioning system.

A thirteenth aspect of the present invention provides the air conditioning system control method according to the eleventh aspect of the present invention, in which the air conditioning system starts up the mold prevention operation mode of a non-operative device among the plurality of indoor units and/or ends the mold prevention operation mode of an operative device among the plurality of indoor units, based on a received command.

According to the foregoing configuration, in a case of a multifunctional air conditioner, the air conditioning system starts up the non-operative device and/or ends the mold prevention operation mode, in accordance with a user's request (e.g., a request issued from an external control device). Control with priority on user's comfortability is thus performed based on the preferential command from the user.

A fourteenth aspect of the present invention provides the air conditioning system control method according to any one of the first to tenth, twelfth, and thirteenth aspects of the present invention, in which the control unit of the air conditioning system includes an external control device that displays an operating state in the mold prevention operation mode.

According to the foregoing configuration, for example, an external control device such as a wired controller or a mobile terminal application may display the operating state in the mold prevention operation mode. This configuration therefore achieves visualization of the operating mode and causes the user to intuitively grasp the progress of the mode.

With reference to <FIG>, first, a brief description will be given of an air conditioning system <NUM> to which an air conditioning system control method according to an embodiment of the present invention is applied. <FIG> is a schematic diagram of a pipeline in an air conditioning system to which an air conditioning system control method according to an embodiment of the present invention is applied.

The air conditioning system <NUM> includes an outdoor unit <NUM> and an indoor unit <NUM>. The air conditioning system <NUM> is capable of executing ordinary operation modes including a cooling operation mode, a heating operation mode, an air blowing operation mode, and the like and is also capable of executing a mold prevention operation mode (a combination of the ordinary operation modes). The mold prevention operation mode refers to consequently decreasing a relative humidity in an internal environment of the entire indoor unit <NUM> (i.e., drying the indoor unit <NUM>). The mold prevention operation mode may be a combined operation mode that removes moisture from components of the indoor unit <NUM>, such as an indoor fan <NUM>, an indoor heat exchanger <NUM>, and a drain pan (not illustrated), thereby achieving an object of destroying the propagation and survival environment of bacteria and mold. The mold prevention operation mode may also be a combined operation mode that blows moisture off the indoor heat exchanger <NUM> or causes moisture on the indoor heat exchanger <NUM> to drop off and evaporates moisture inside the indoor unit <NUM>. However, the mold prevention operation mode is not intended to be interpreted in a narrower sense as being constituted with only an inside humidity decrease stage that decreases a humidity in an internal environment of an air conditioner. Conversely, the mold prevention operation mode should be broadly defined in a broader sense and may non-exclusively include an inside cleaning operation for removing mold grown on the indoor fan <NUM>, indoor heat exchanger <NUM>, or drain pan (not illustrated) inside the indoor unit <NUM>.

The indoor unit <NUM> includes components such as the indoor fan <NUM>, the indoor heat exchanger <NUM>, and an electric valve (an indoor adjustment valve) <NUM>. The outdoor unit <NUM> includes components such as a compressor <NUM>, an outdoor fan <NUM>, an outdoor heat exchanger <NUM>, a flow channel switching valve <NUM>, and an electric valve (an outdoor adjustment valve) <NUM>. The compressor <NUM>, outdoor heat exchanger <NUM>, flow channel switching valve <NUM>, and electric valve (outdoor adjustment valve) <NUM> inside the outdoor unit <NUM> as well as the indoor heat exchanger <NUM> inside the indoor unit <NUM> constitute a refrigerant circuit as main members.

The indoor fan <NUM> inside the indoor unit <NUM> rotates when being driven, so that a negative pressure at the suction side of the indoor fan <NUM> generates an airflow in a blowing direction. The indoor fan <NUM> is thus capable of taking in indoor air from a room, providing the air into the indoor unit <NUM>, and blowing the air, subjected to heat exchange in the indoor heat exchanger <NUM>, out of the indoor unit <NUM> toward the room.

The outdoor fan <NUM> inside the outdoor unit <NUM> rotates when being driven. During, for example, a cooling operation, the outdoor fan <NUM> takes in outdoor air and provides the air into the outdoor unit <NUM>, so that the outdoor heat exchanger <NUM> performs heat radiation.

The air conditioner also includes a control unit <NUM> for controlling operations of the respective components inside the indoor unit <NUM> and outdoor unit <NUM>. The control unit <NUM> controls the operations of the respective components, thereby executing the respective operation modes in the air conditioning system <NUM>.

The air conditioning system <NUM>, when satisfying a preset condition, starts execution of the mold prevention operation mode. In this case, the air conditioning system <NUM> starts to execute the mold prevention operation mode. The mold prevention operation mode includes the inside humidity decrease stage. The mold prevention operation mode may non-exclusively include an inside cleaning operation for removing mold grown on the indoor heat exchanger <NUM> and/or drain pan inside the indoor unit <NUM>. In a case where the mold prevention operation mode includes other operations in addition to the inside humidity decrease stage, the inside humidity decrease stage is executed last.

With reference to <FIG> and <FIG>, next, a description will be given of the inside humidity decrease stage in the mold prevention operation mode of the air conditioning system control method according to the embodiment of the present invention. <FIG> is a main flowchart of the inside humidity decrease stage in the mold prevention operation mode of the air conditioning system control method according to the embodiment of the present invention. <FIG> is a sub-flowchart of a humidity increase process at the inside humidity decrease stage in the mold prevention operation mode of the air conditioning system control method according to the embodiment of the present invention.

In the mold prevention operation mode, when the inside humidity decrease stage is executed, as illustrated in <FIG>, first, in step S100, the control unit <NUM> acquires a relative humidity H1 inside the indoor unit <NUM> before the inside humidity decrease stage, that is, a relative humidity H1 at the start of the inside humidity decrease stage.

In step S200, next, the control unit <NUM> determines whether the acquired relative humidity H1 inside the indoor unit <NUM> at startup reaches a preset value (e.g., a relative humidity of <NUM>%).

When the control unit <NUM> determines in step <NUM> that the relative humidity H1 inside the indoor unit <NUM> at the startup is lower than the preset value (i.e., the relative humidity H1 does not reach the preset value) ("NO" in step S200; see step S210 in <FIG>), then the control unit <NUM> carries out step S300 (the humidity increase process) to be described later with reference to <FIG>.

On the other hand, when the control unit <NUM> determines in step <NUM> that the relative humidity H1 inside the indoor unit <NUM> at the startup is the preset value or more (i.e., the relative humidity H1 reaches the preset value) ("YES" in step S200), then the control unit <NUM> executes a humidity decrease process illustrated in <FIG>.

In the rainy season, the continuous rainy weather, or the season with high humidity such as the rainy weather, or after the end of a long-hours cooling or dehumidifying operation in summer, the humidity (the relative humidity) inside the indoor unit <NUM> already satisfies a high-humidity condition. In such a case, the control unit <NUM> may directly execute the humidity decrease process.

On the other hand, occasionally, the humidity (the relative humidity) inside the indoor unit <NUM> takes a normal value during the daytime or the humidity (the relative humidity) inside the indoor unit <NUM> is in a relatively dry state in a case where a heating operation is carried out for long hours in winter. In such a case, in carrying out a mold prevention operation, it is necessary to increase the humidity (i.e., transition to the humidity increase process) and then decrease the humidity (i.e., transition to the humidity decrease process) in order to produce an advantageous effect of mold prevention processing.

Therefore, the inside humidity decrease stage in the present invention is not intended to be interpreted in a narrower sense as including only a humidity decrease process of decreasing a humidity (a relative humidity) inside an air conditioner. Conversely, the inside humidity decrease stage in the present invention should be broadly defined in a broader sense as a stage that consequently decreases a humidity (a relative humidity) inside an air conditioner, that is, a stage that may non-exclusively include a humidity increase process of increasing a humidity (a relative humidity) inside an air conditioner for a specific purpose.

In the humidity increase process (step S300), as illustrated in <FIG>, when the control unit <NUM> determines in step <NUM> that the relative humidity H1 inside the indoor unit <NUM> at the startup is lower than the preset value (e.g., the relative humidity of <NUM>%) (i.e., the relative humidity H1 does not reach the preset value), that is, in a case of step S210 in <FIG>, then the control unit <NUM> carries out step S310 (the cooling operation).

In step S310, the cooling operation is carried out in the same manner as that of an ordinary cooling operation to be carried out in the cooling operation mode as one of the ordinary operation modes of the air conditioning system <NUM>. During the cooling operation, the control unit <NUM> controls the components including the compressor <NUM> to cause a refrigerant to flow into the refrigerant circuit. In this case, the indoor heat exchanger <NUM> functions as an evaporator. During the cooling operation, preferably, the control unit <NUM> intermittently operates the indoor fan <NUM>; however, the indoor fan <NUM> does not necessarily rotate.

After carrying out step S310 (the cooling operation) for a predetermined time, in step S320, the control unit <NUM> stops the compressor <NUM>. In step S330, next, the control unit <NUM> determines whether frost formation occurs in the indoor heat exchanger <NUM>.

When the control unit <NUM> determines in step S330 that frost formation occurs in the indoor heat exchanger <NUM> ("YES" in step S330), then in step S331, the control unit <NUM> keeps the indoor fan <NUM> operating. The processing then proceeds to step S340. This configuration thus enables prompt defrosting and additionally achieves a prompt increase in inside humidity.

On the other hand, when the control unit <NUM> determines in step S330 that no frost formation occurs in the indoor heat exchanger <NUM> ("NO" in step S330), then in step S332, the control unit <NUM> stops the indoor fan <NUM>. The processing then proceeds to step S340. Adjusting the operating state of the indoor fan <NUM> in accordance with the specific state of the indoor heat exchanger <NUM> improves control accuracy, achieves energy saving, advantageously stabilizes the air conditioning system <NUM>, and ensures user's comfortability.

In step S340, the control unit <NUM> determines whether a humidity adjustment value H1' inside the indoor unit <NUM>, which has been subjected to the humidity increase (step S310, step S320, step S330, and step S331 or <NUM>) by a present predetermined cycle, reaches the preset value (i.e., the preset value (the relative humidity of <NUM>%) in step S200).

When the control unit <NUM> determines in step S340 that the humidity adjustment value H1' inside the indoor unit <NUM> is still lower than the preset value (i.e., the humidity adjustment value H1' does not reach the preset value) ("NO" in step S340), the processing returns to step S310 in which the control unit <NUM> continuously executes the humidity increase by a subsequent predetermined cycle.

On the other hand, when the control unit <NUM> determines in step S340 that the humidity adjustment value H1' inside the indoor unit <NUM> is the preset value or more (i.e., the humidity adjustment value H1' reaches the preset value) ("YES" in step S340), then the control unit <NUM> executes the humidity decrease process illustrated in <FIG>.

According to an example as an embodiment of the present invention, the humidity decrease process may include an air blowing operation (step S400) and a heat applying operation (step S500). The control unit <NUM> carries out step S400 (the air blowing operation) first. After executing step S400 (the air blowing operation) for a predetermined time, the control unit <NUM> then carries out step S500 (the heat applying operation). However, the present invention is not limited thereto. For example, the humidity decrease process does not necessarily include the heat applying operation (step S500), and may include only the air blowing operation (step S400).

In step S400, the air blowing operation may be equal in air blowing power to an ordinary air blowing operation to be carried out in the air blowing operation mode as one of the ordinary operation modes of the air conditioning system <NUM> or may be different in air blowing power from the ordinary air blowing operation after the air flow volume is adjusted by an air flow volume adjustment unit. For example, a powerful air blowing operation or a powerless air blowing operation can be mentioned. During the air blowing operation, the control unit <NUM> turns on the indoor fan <NUM> and controls the rotation of the indoor fan <NUM>. However, since the control unit <NUM> controls the rotation while stopping the compressor <NUM>, the refrigerant does not flow into the refrigerant circuit.

During the air blowing operation in this case, the control unit <NUM> controls a tilt angle of an air guide plate such that air blown out through an air blow-out port is not directly directed to a person in the room.

In step S500, the heat applying operation may achieve heat application in the same manner as that of an ordinary heating operation to be carried out in the heating operation mode as one of the ordinary operation modes of the air conditioning system <NUM> or may achieve heat application using a heat applying member, which is different from the ordinary heating operation. In a process of achieving heat application by the heating operation, the control unit <NUM> controls the components including the compressor <NUM> to cause the refrigerant to flow into the refrigerant circuit. In this case, the indoor heat exchanger <NUM> functions as a radiator. During the heat applying operation, preferably, the control unit <NUM> intermittently operates the indoor fan <NUM>; however, the indoor fan <NUM> does not necessarily rotate.

By the inside humidity decrease stage ("humidity decrease process" or "humidity increase process + humidity decrease process"), in step S600, the control unit <NUM> decreases a relative humidity H from the relative humidity H1 at the startup to a target humidity H2 (also called "a relative humidity inside the indoor unit <NUM> subjected to humidity decrease by the inside humidity decrease stage") within a predetermined time T (e.g., one hour). The target humidity H2 is not more than <NUM> times the relative humidity H1 at the startup. That is, a relation of H2/H1 ≤ <NUM> is preferably established.

The air conditioning system control method according to the embodiment of the present invention includes the inside humidity decrease stage. At the inside humidity decrease stage, the control unit <NUM> acquires the relative humidity H1 inside the indoor unit <NUM> at the startup. The control unit <NUM> then controls the air conditioning system <NUM>. When the relative humidity (H1) inside the indoor unit <NUM> at the startup is the preset value or more, the control unit <NUM> executes the humidity decrease process of decreasing the relative humidity inside the indoor unit <NUM> from the relative humidity H1 at the startup. The humidity decrease process includes the air blowing operation of blowing air out of the indoor unit <NUM> toward the room. By the inside humidity decrease stage, the relative humidity inside the indoor unit <NUM> is decreased to the target humidity H2 within the predetermined time T so that the ratio between the target humidity H2 and the relative humidity H1 at the startup, that is, the ratio of H2/H1 falls within the preset range that enables destruction of the propagation and survival environment of bacteria and mold. Therefore, true mold prevention inside the indoor unit <NUM> can be realized by decreasing the relative humidity inside the indoor unit <NUM> and destroying the propagation and survival environment of bacteria and mold. This configuration is different from a simple one-time cleaning after propagation of bacteria and mold.

In addition, since the indoor unit <NUM> is quickly dried before a mold cystoid spore germination period, the growth of mold is reset again. This configuration therefore inhibits germination of mold and considerably reduces the number of bacteria as compared with the number of bacteria in a case where an indoor unit is dried naturally.

According to the present invention, the control unit <NUM> causes, for example, the humidity sensor to detect the temperature inside the indoor unit <NUM> (the initial humidity H1, that is, the relative humidity at the startup, the humidity adjustment value H1' subjected to the humidity increase by the present predetermined cycle in the humidity increase process, or the relative humidity H in the humidity decrease process) in real time. This configuration enables an immediate response to a change in temperature inside the indoor unit <NUM>, the change being fed back from the humidity sensor. This configuration thus improves control accuracy.

When the relative humidity H1 at the startup reaches the preset value (e.g., the relative humidity of <NUM>%), the inside of the air conditioner at this time is already in the high-humidity state. The control unit <NUM> merely controls the air conditioning system <NUM> and starts to directly execute the humidity decrease process. Therefore, the control unit <NUM> does not need to execute the humidity increase process prior to the humidity decrease process. This configuration therefore efficiently achieves mold prevention and sterilization inside the indoor unit <NUM> in an energy-saved manner.

When the relative humidity H1 at the startup does not reach the preset value (e.g., the relative humidity of <NUM>%), the inside of the air conditioner at this time is at a normal humidity and, in turn, is in a relatively dry state. In this case, although the inside humidity decrease process is executed, executing the humidity increase process and then executing the humidity decrease process may cause the ratio of H2/H1 to more advantageously fall within the preset range that enables destruction of the propagation and survival environment of bacteria and mold.

The ratio between the target humidity H2 at the inside humidity decrease stage (the target value of the relative humidity H) and the relative humidity H1 at the startup (the initial value of the relative humidity H), that is, the ratio of H2/H1 is <NUM> or less. Preferably, the ratio of H2/H1 is <NUM> to <NUM>. This configuration therefore ensures an advantageous effect of mold prevention and improves control accuracy, without imposing an excessive load on the air conditioner.

The control unit <NUM> executes the cooling operation during which the indoor heat exchanger <NUM> functions as an evaporator, in the execution of the humidity increase process at the inside humidity decrease stage. Therefore, controlling the refrigerant that circulates in the refrigerant circuit by the compressor <NUM> achieves the humidity increase on the secondary side (the blow-out side) of the indoor heat exchanger <NUM>, produces an advantageous effect of the humidity increase, and improves control accuracy.

The control unit <NUM> stops the compressor <NUM> in the execution of the humidity increase process at the inside humidity decrease stage. This configuration therefore achieves the humidity increase on the primary side (the suction side) of the indoor heat exchanger <NUM>, that is, the humidity increase inside the entire indoor unit <NUM>. This configuration thus ensures the advantageous effects of the mold prevention and sterilization.

The control unit <NUM> intermittently operates the indoor fan <NUM> during the execution of the humidity increase process at the inside humidity decrease stage. Alternatively, in the case of the cooling operation, the control unit <NUM> determines whether frost formation occurs in the indoor heat exchanger <NUM>. When frost formation occurs in the indoor heat exchanger <NUM>, the control unit <NUM> stops the indoor fan <NUM>. When no frost formation occurs in the indoor heat exchanger <NUM>, the control unit <NUM> continuously operates the indoor fan <NUM>. This configuration therefore adequately mixes airflows inside the indoor unit and increases the humidity inside the entire air conditioner.

During the execution of the humidity decrease process at the inside humidity decrease stage, the control unit <NUM> carries out the air blowing operation to decrease the relative humidity inside the indoor unit <NUM>. Alternatively, the control unit <NUM> carries out the air blowing operation and the heat applying operation. Carrying out the air blowing operation promptly and effectively decreases the humidity inside the indoor unit <NUM>, which makes a user comfortable without increasing a temperature of air to be blown out of the indoor unit <NUM>. On the other hand, carrying out the heat applying operation achieves further dry and mold prevention and produces more preferable advantageous effects of sterilization.

In the case of the heat applying operation, the control unit <NUM> intermittently operates the indoor fan <NUM>. This configuration therefore increases a temperature difference in air to be blown out of the indoor unit <NUM> and prevents user's experience from being affected.

Those skilled in the art can easily conceive other advantages and modifications. In a broader sense, therefore, the present invention is not limited to the specific details and typical examples illustrated and described herein. The present invention may be modified without departing from the scope of the invention which is defined by the accompanying claims.

According to the embodiment of the present invention, in step S300 (the humidity increase process), the control unit <NUM> carries out the cooling operation (step S310), thereby increasing the humidity (the relative humidity) inside the indoor unit <NUM>; however, the present invention is not limited to this example. In step S300 (the humidity increase process), for example, the control unit <NUM> may carry out a dehumidifying operation in the same manner as that of an ordinary dehumidifying operation to be carried out in the dehumidifying operation mode as one of the ordinary operation modes of the air conditioning system <NUM>, thereby increasing the humidity (the relative humidity) inside the indoor unit <NUM>. In step S300 (the humidity increase process), alternatively, the control unit <NUM> may increase the humidity (the relative humidity), using a humidifying member so as to differ from the cooling operation mode or dehumidifying operation mode as one of the ordinary operation modes.

In increasing the humidity (the relative humidity) by executing the dehumidifying operation or using the humidifying member, step S310 and step S340 are merely suspended in step S300 (the humidity increase process) indicated by a broken line in <FIG>. In step S310, the control unit <NUM> increases the humidity by executing the dehumidifying operation or using the humidifying member. In step S340, the control unit <NUM> determines whether the humidity adjustment value H1' inside the indoor unit <NUM> reaches the preset value.

In the foregoing example, the preset condition is that the relative humidity inside the indoor unit reaches the predetermined value. The humidity sensor is disposed inside the indoor unit. Preferably, the humidity sensor is disposed near the indoor heat exchanger. For example, when the humidity sensor is placed at a position distant by <NUM> from the upstream or downstream side of the indoor heat exchanger on the airflow path, the humidity sensor is capable of directly and accurately detecting the inside humidity. When the inside relative humidity is in the high-humidity state, the control unit <NUM> may start to carry out the mold prevention operation.

The preset condition is that a humidity of indoor air reaches a predetermined value. For example, in an environment such as the rainy season or the continuous rainy weather, a humidity of air is in a high-humidity state. When the humidity sensor detects an indoor humidity of <NUM>% or more, the control unit <NUM> may start to carry out the mold prevention operation.

The preset condition is that an integrated operating time of the cooling or dehumidifying operation reaches a predetermined value. In summer, when the air conditioner frequently carries out the cooling operation or the dehumidifying operation, condensate is retained inside the indoor unit without fail. When the operating time is integrated for a certain period, mold and bacteria tend to propagate. The control unit <NUM> may start to carry out the mold prevention operation at this timing.

The preset condition is that an integrated time of continuous increase in environmental temperature reaches a predetermined value. For example, when the control unit <NUM> determines from detection of the environmental temperature that mold and bacteria tend to propagate in the high-temperature and high-humidity season (summer), then the control unit <NUM> may start to carry out the mold prevention operation.

In the foregoing example, the humidity sensor may be placed on the suction port in the indoor unit. The humidity sensor detects a return air humidity in the room. The humidity sensor calculates a dew-point temperature based on a temperature and humidity of the return air in the room. In addition, the humidity sensor calculates a water content based on an indoor heat cross area S and a difference ΔT between the dew-point temperature and an evaporation temperature of the indoor heat exchanger. The humidity sensor thus estimates an inside relative humidity. Moreover, when the humidity sensor is placed on the blow-out port in the indoor unit, the humidity sensor detects a relative humidity value of an airflow blown out through the blow-out port. The humidity sensor thus determines whether the inside humidity at the humidity increase stage is in a high-humidity state or whether the inside humidity at the humidity decrease stage is decreased to a target humidity.

Claim 1:
An air conditioning system control method for controlling an air conditioning system (<NUM>) including an outdoor unit (<NUM>), an indoor unit (<NUM>), and a control unit (<NUM>), the outdoor unit (<NUM>) including a compressor (<NUM>) and an outdoor heat exchanger (<NUM>), the indoor unit (<NUM>) including an indoor heat exchanger (<NUM>), the compressor (<NUM>), the outdoor heat exchanger (<NUM>), and the indoor heat exchanger (<NUM>) being connected with pipes to constitute a refrigerant circuit in which a refrigerant circulates, the control unit (<NUM>) being configured to control constituent members of the refrigerant circuit in the air conditioning system (<NUM>) and to execute a mold prevention operation mode,
wherein
the mold prevention operation mode includes an inside humidity decrease stage,
at the inside humidity decrease stage, when a preset condition is satisfied, the control unit (<NUM>) controls the air conditioning system (<NUM>) and starts up a humidity decrease process of decreasing a relative humidity,
the humidity decrease process includes an air blowing operation of blowing air out of the indoor unit (<NUM>) toward a room, characterized in that
by the inside humidity decrease stage, a relative humidity (H) inside the indoor unit (<NUM>) is decreased within a predetermined time (T) such that a ratio between the relative humidity (H) and a relative humidity (H1) before the inside humidity decrease stage falls within a preset range that enables destruction of propagation and a survival environment of bacteria and mold;
wherein the preset condition includes one of or at least two of a condition that the relative humidity inside the indoor unit reaches a predetermined value, a condition that a humidity of indoor air reaches a predetermined value, a condition that an integrated operating time of a cooling operation or a dehumidifying operation reaches a predetermined value, and a condition that an integrated time of continuous increase in environmental temperature reaches a predetermined value.